Patent Application
20220355997
Certain embodiments of the present disclosure relate to a system for transporting fragile objects.
Fragile objects may be at risk of becoming damaged when transported from one location to another. To minimize the risks, fragile objects are traditionally transported in wooden crates. The wooden crates are cushioned with foam intended to protect the fragile object in the event that the wooden crate is dropped. Unfortunately, traditional wooden crates may fail to adequately protect fragile objects from damage.
Embodiments of the present disclosure may reduce the risk of a fragile object becoming damaged during transit. For example, disclosed herein is a vibration-isolating system.
According to certain embodiments, a system comprises an outer box and an inner box suspended within the outer box by one or more vibration isolators. The inner box comprises a mounting system adapted to facilitate mounting one or more objects within the inner box.
As examples, the one or more objects that the mounting system is adapted to facilitate mounting within the inner box may comprise one or more fragile objects, such as one or more art objects, for example, one or more paintings (e.g., stretched canvases painted with artwork). In certain embodiments, the plurality of vibration isolators are tuned to provide vibration isolation in a damage frequency range associated with the one or more objects. For example, with respect to embodiments where the fragile object is a painting, the plurality of vibration isolators are tuned to a natural frequency that reduces damaging vibrations imparted on the stretched canvas so as to prevent paint from cracking, crazing, or separating from the stretched canvas.
The system may include one or more additional features, such as any one or more of the following:
In certain embodiments, the inner box further comprises a front cover and a back cover. The front cover is adapted to facilitate access to a first mounting surface of the mounting system when the front cover is open, and the back cover is adapted to facilitate access to a second mounting surface of the mounting system when the back cover is open. An interior portion of the inner box is buffered from changes in temperature and/or relative humidity when the front cover and the back cover are closed.
In certain embodiments, the outer box comprises a plurality of outer box walls, the inner box comprises a plurality of inner box walls, and the mounting system comprises a mounting surface. The plurality of outer box walls include an outer box top wall, an outer box bottom wall, and a plurality of outer box side walls. The plurality of inner box walls include an inner box top wall, an inner box bottom wall, and a plurality of inner box side walls. The inner box is suspended such that when the system is in a stationary and upright orientation, the mounting surface is oriented vertically and none of the inner box walls directly contacts any of the outer box walls.
In certain embodiments, the mounting system comprises a first mounting board and a second mounting board. The second mounting board is arranged parallel to the first mounting board and separated from the first mounting board by a distance. As an example, in certain embodiments, the distance is at least 25 millimeters. The distance is used as a strategy to achieve the desired stiffness. The stiffness then in turn is used to achieve the desired natural frequency. As another example, in certain embodiments, the distance yields a natural frequency of the first mounting board and the second mounting board greater than or equal to 100 Hz.
In certain embodiments, the mounting system further comprises a plurality of mounting bolsters. Each mounting bolster is adapted to facilitate mounting the one or more objects onto a mounting surface of the mounting system. Each mounting bolster comprises a positioning mechanism. The positioning mechanism can be arranged in a first mode or a second mode. When the positioning mechanism is arranged in the first mode, the positioning mechanism is adapted to facilitate moving the mounting bolster in any direction along the mounting surface. When the positioning mechanism is arranged in the second mode, the positioning mechanism is adapted to facilitate locking the mounting bolster into a fixed position on the mounting surface. As an example, in certain embodiments, the positioning mechanism comprises one or more magnets. As another example, in certain embodiments, the positioning mechanism comprises Velcro.
In certain embodiments, each mounting bolster comprises a pad adapted to secure an object to the mounting bolster when the pad is in a first position and release the object from the mounting bolster when the pad is in a second position. In certain embodiments, the pad is adapted to be locked into the first position using a torque wrench.
In certain embodiments, each of the plurality of vibration isolators attaches to the inner box at a respective attachment point. Each attachment point avoids locations within a distance of an inner box corner nearest the respective attachment point. As a first example, in certain embodiments, the plurality of vibration isolators include at least one vibration isolator with an attachment point along a vertical surface of the inner box and the distance comprises at least 10% of a vertical dimension of the inner box. As a second example, in certain embodiments, the plurality of vibration isolators include at least one vibration isolator with an attachment point along a horizontal surface of the inner box and the distance comprises at least 10% of a horizontal dimension of the inner box. In some embodiments, each attachment point is substantially centered with respect to a depth dimension of the inner box.
In certain embodiments, each of the plurality of vibration isolators attaches to the inner box at a respective attachment point, and each attachment point avoids locations for which a modal response associated with the location exceeds a threshold.
In certain embodiments, the plurality of vibration isolators comprises at least four vibration isolators, wherein each of the four vibration isolators is focused at the center of gravity of the inner box.
In certain embodiments, the plurality of vibration isolators comprises at least a first pair of vibration isolators diagonally opposed through a center of gravity of the inner box and a second pair of vibration isolators diagonally opposed through the center of gravity of the inner box.
In certain embodiments, each vibration isolator in the plurality of vibration isolators is tuned such that a force-displacement dynamic of said vibration isolator is within a pre-determined tolerance of a force-displacement dynamic of the other vibration isolators.
In certain embodiments, the plurality of vibration isolators are tuned to a natural frequency below a damage range associated with the one or more objects.
In certain embodiments, the plurality of vibration isolators comprises at least one multi-stage vibration isolator, the at least one multi-stage vibration isolator adapted to provide a first mode of vibration isolation in response to a first vibration amplitude and to provide a second mode of vibration isolation in response to a second vibration amplitude. For example, in certain embodiments, the second vibration amplitude is greater than the first vibration amplitude and the second mode of vibration isolation is more rigid than the first mode of vibration isolation. In certain embodiments, the at least one multi-stage vibration isolator is further adapted to provide a third mode of vibration isolation, a jounce bumper, that provides vibration protection with the response to a third vibration amplitude.
In certain embodiments, the system further comprises a loading mechanism adapted to hold the mounting system steady when in a first mode and to engage the plurality of vibration isolators when in a second mode. Certain embodiments further comprise a stopper that prevents at least one of the outer box or the inner box from closing or locking when the loading mechanism is in the first mode.
Certain embodiments of the present disclosure may provide one or more technical advantages. Certain embodiments may protect a canvas painting, art, or other fragile object from vibration and/or shock that can occur during transit. As an example, certain embodiments may provide a vibration-isolating system that attenuates and damps vibrations and/or reduces transmitted shock experienced by the object in transit. The system can be configured to isolate damaging frequencies and/or to absorb shock in the event of a drop. Certain embodiments may tune or customize protection based on the particular object being transported, for example, depending on the fundamental damage frequency of the object. Certain embodiments may have all, some, or none of these advantages. Other advantages will be apparent to persons of ordinary skill in the art.
For a more complete understanding of the disclosed embodiments and their features and advantages, reference is now made to the following description, taken in conjunction with the accompanying drawings, in which:
Fragile objects are traditionally transported in wooden crates cushioned with foam. The foam is intended to protect the fragile object in the event that the wooden crate is dropped or in a collision. Traditional wooden crates, however, may fail to adequately protect the fragile object from damage. For example, the fragile object may be subjected to significant vibrations when transported by a truck, aircraft, or other vehicle. As the encountered transit vibrations approach the resonant frequencies of the fragile object, those vibrations cause the fragile object to vibrate with increasing amplitude, stressing the materials and structures of the object which results in cracks or other damage. As an example, the fragile object may be a painting on a canvas. When resonant vibrations occur, the canvas oscillates and the paints restrain the canvas movement through tension and compression thereby damping the kinetic energy of the canvas. If the stresses to the adhesion and cohesion bonds remaining in the aged paints exceed stress limits, the paint will crack and separate either at the point of adhesion of the paint to the canvas or between paint layers. The paint layers increasingly transform from a semi-continuous film to a series of fragmented sections. Every time a crack forms, that crack becomes the focal point of movement in that area. As more movement occurs, the canvas and paints become more and more damaged at the cracks. As the painting ages, it tends to become less flexible and more brittle. Thus older paintings are increasingly prone to damage as a result of travel vibrations.
The most damaging transit-related vibrations generally occur at frequencies similar to the object's natural frequency. At the object's natural frequency, the amplitude may become very great, limited only by the system's internal damping. The first natural frequency of a painting will generally be in the range of approximately 5-50 Hz and the natural frequency of a glass sculpture or ceramic will generally be in the range of approximately 150-1000 Hz. In developing the systems and methods disclosed herein, it was discovered that traditional wooden crates not only fail to reduce damaging vibrations, they transmit and actually amplify many vibrations due to a poorly tuned system natural frequency. For example, testing was performed on a traditional wooden crate configured with accelerometers and scanning laser vibrometers placed or focused on a painting, on the foam cushioning, on the wooden crate, and on the bed of the truck transporting the painting. The testing underscored the data suggested in US MIL-STD-810 for common commercial truck carriers that transit vibrations are greatest in the regions of 10-60 Hz and 100-160 Hz. Testing further demonstrated that traditional wood crates and foam cushioning have relatively low natural frequencies (approximately 20-100 Hz) and therefore amplify transit vibrations up to a frequency of 140% of the system's first natural frequency. If the system's first natural frequency is not tuned low enough, low frequency transit vibrations are amplified to damaging levels. At every configuration in which foam was used, vibration across the fragile payload increased. For example, the displacement energy experienced by a painting cushioned in foam was worse than if the painting had been placed directly on the bed of the truck. By amplifying the displacement energy, the foam increased the risk of damage to the painting.
The results obtained by testing the foam were unexpected because conventionally foam was thought to be beneficial for protecting fragile objects and because foam behaves differently when observed on its own as compared to when it is observed carrying a load. Both in product literature and in experimental tests on engineering shaker tables and actual road tests, cushioning foams made from open-cell polyurethane (PEU) and extruded, closed-cell polyethylene foams exhibit consistent natural frequencies between 3 Hz-100 Hz, depending upon the configurations used as container cushions and the payload compressions created. These are precisely the frequencies transmitted in all modes of motor, rail and air freight transportation. Because the input vibration frequencies approximate or replicate the natural frequencies of the foam cushions, both the cushions and the wood walls of the crate move into phase and amplify the transmitted excursions of the truck bed or wall.
Certain embodiments of the present disclosure may provide solutions to this and other problems associated with traditional systems for transporting fragile objects. For example, certain embodiments may reduce exposure to vibration frequencies that would otherwise damage a fragile object in transit, such as vibrations in lower frequency ranges (e.g., vibrations less than approximately 150 Hz, vibrations less than approximately 100 Hz, or other frequencies depending on the natural frequency of the object being transported). Certain embodiments use a suspension system to provide tunable protection from vibration and shock. For example, the suspension system may be implemented using a box-in-box design comprising an outer box and an inner box. The inner box is suspended within the outer box by a plurality of vibration isolators, and the inner box comprises a mounting system adapted to facilitate mounting one or more objects within the inner box. The isolators may be tunable to protect the objects from their most damaging vibrations (e.g., based on the natural frequency of the object). The tuning of the isolators can be improved by positioning the one or more objects such that the mass of the suspended components (e.g., the inner box containing the mounting system and the objects carried by the mounting system) retains its center of gravity (CG) at the isolator focal point. The isolators are focused on the system's center of gravity in order to decouple vibration modes. In this manner, an object would move up and down in response to vertical vibration, as opposed to side-to-side or twisting. Because the position of the one or more objects can affect the tuning of the isolators, disclosed herein is an adjustable load-positioning system that allows for adjusting the position of the one or more objects.
For a more complete understanding of the present invention and the advantages thereof, reference is now made to the following description and the accompanying drawings, wherein like numerals are used for like and corresponding parts of the various drawings.
In certain embodiments, the outer box 105 comprises a plurality of outer box walls, and the inner box 110 comprises a plurality of inner box walls. For example, the outer box 105 may comprise an outer box top wall, an outer box bottom wall, and a plurality of outer box side walls (e.g., left side, right side, front side, and back side). Similarly, the inner box 110 may comprise an inner box top wall, an inner box bottom wall, and a plurality of inner box side walls (e.g., left side, right side, front side, and back side). Certain embodiments suspend the inner box 110 such that when the system 100 is in a stationary and upright orientation, none of the inner box walls directly contacts any of the outer box walls. This arrangement allows the inner box 110 some range of motion within the outer box 105 in order to respond to vibrations, such as vibrations that system 100 may be subjected to when transported. In this manner, system 100 may protect the one or more objects 120 from damaging vibrations. Examples of objects 120 that may be protected by system 100 include fragile objects, such as museum specimens, artifacts, art objects (e.g., paintings, such as stretched canvases painted with artwork; sculptures, such as glass, marble, or ceramic sculptures; etc.), scientific equipment, musical instruments, and so on. As further explained below, the plurality of vibration isolators 130 can be tuned to a natural frequency that reduces damaging vibrations imparted on the one or more objects 120. In the case of a paintings, for example, the tuning can reduce damaging vibrations imparted on the stretched canvas so as to prevent paint from cracking, crazing, or separating from the stretched canvas. In certain embodiments, the frequency range to be attenuated begins at approximately 8-10 Hz and ends at approximately 40-50 Hz, such as 8-40 Hz, 8-50 Hz, 10-40 Hz, or 10-50 Hz, among others.
The box-in-box design illustrated in
In general, when closed, the outer box 105 may protect the inner box 110 from exposure to an environment outside of the outer box 105 (e.g., light, temperature, humidity, etc.). Similarly, when closed, the inner box 110 may protect the contents of the inner box 110 from exposure to an environment outside of the inner box 110. Protecting the contents of the inner box 110 may include buffering an interior portion of the inner box 110 from changes in temperature and/or relative humidity. In certain embodiments, system 100 may include one or more environmental buffers that contribute to buffering the inside of the inner box 110 from changes in temperature and/or relative humidity. Examples of environmental buffers include thermal buffers (such as insulation layers or thermal phase change material, which may be obtained from Cryopak™ or other manufacturers) and humidity buffers (such as conditioned silica gel material or ArtSorb, which may be obtained from Fuji Silysia Chemical™). As an example, in certain embodiments, the outer box 105's walls and/or the inner box 110's may comprise or may be lined with thermal insulation, volatile organic pollutant absorbents or other environmental buffers. In addition, or in the alternative, certain embodiments position environmental buffers within inner box 110, for example, by placing one or more environmental buffers on, in, or between components of the mounting system (e.g., components such as mounting boards 114 described below with respect to
The outer box 105 may be any box suitable to contain the inner box 110. The inner box 110 may be any box suitable to carry one or more objects 120. In certain embodiments, the outer box 105 and/or the inner box 110 may be a custom-made box. The custom-made box may be built using parts specified on a parts list. In certain embodiments, the parts may be standard parts, which may help to ensure that the parts are reliable and readily available from various manufacturers. Standard parts refer to parts that are based on specifications defined by a standards group, such as the ASTM International, the International Organization for Standardization (ISO), or other standards groups. In certain embodiments, the parts list may include the materials and dimensions of the box and related parts, such as a number and type of fasteners (e.g., screws, bolts, hinges, channels, guides, locking mechanisms, snaps, gaskets, adhesives, etc.) for coupling components of the box together.
The dimensions of the inner box 110 may be specified to accommodate the size of objects 120 to be carried in the inner box 110. In an embodiment, the inner box 110 can be dimensioned to carry a painting up to 44×44 inches in the x-y plane and to provide lateral stability in the z-direction. Example dimensions of inner box 110 may be in the range of approximately 48 inches to 60 inches in length, approximately 48 inches to 60 inches in height, and approximately 24 inches to 60 inches in width. However, other dimensions could be used, depending on materials used and the object(s) 120 to be carried. Other embodiments may be dimensioned to accommodate a smaller or larger object 120. The dimensions of the outer box 105 can be specified to accommodate the size of the inner box 110 and the vibration isolators 130 that suspend the inner box 110 within the outer box 105. In certain embodiments, the dimensions and/or materials may be specified to improve stability and reduce a likelihood of tipping over the system 100. As an example, the outer box 105 may be dimensioned with a relatively large width compared to its height (such as a width greater than or equal to 35% of its height) to reduce a likelihood of tipping. As another example, the outer box 105's mass may be relatively high and its center of gravity relatively low in order to reduce a likelihood of tipping.
The walls of the outer box 105 and/or the inner box 110 may comprise any suitable material. The material may be selected to impart certain properties, such as lightweight, sturdy, scalable in size, effective at reducing vibrations, puncture resistant, able to provide protection from a catastrophic event (e.g., collision, drop, fall, etc.), and/or able to provide protection from the elements (e.g., moisture, steam, water, heat, dust, smoke, etc.). Certain embodiments use a rigid, high natural frequency, puncture-resistant material, such as metal, plastic, synthetic composite structure, and/or honeycomb structure. An example of such a material includes polypropylene honeycomb in aluminum extrusion. In some embodiments, one or more surfaces of the outer box 105 or the inner box 110 may comprise a Kevlar-like facing that reduces puncture risk. In addition, or in the alternative, in some embodiments, a skin may be applied to one or more surfaces of the outer box 105 or the inner box 110. As an example, a replaceable skin made of vinyl or similar material may be applied to one or more outward-facing surfaces. The skin may protect the box from abrasion or dirt. In some embodiments, a skin may be removable so that it can be replaced if it begins to show signs of wear and tear (e.g., dirt, scratches, etc.). In certain embodiments, the skin may have a color or a design, such as a logo or a box number, which may help distinguish the box from other boxes.
The plurality of vibration isolators 130 suspend the inner box 110 within the outer box 105. For example, each vibration isolator 130 may couple between a wall of the outer box 105 and a wall of the inner box 110 (e.g., a vibration isolator 130 may couple between an interior-facing surface of one of the outer box 105's walls and an exterior-facing surface of one of the inner box 110's walls). Certain embodiments may include, mounts, brackets, and/or other structures that facilitate coupling vibration isolators 130 to the outer box 105 and the inner box 110. The vibration isolators 130 may be coupled at attachment points, as further explained below with respect to
Any suitable vibration isolators 130 may be used. Examples of vibration isolators 130 include multi-stage vibration isolators (such as that described below with respect to
In certain embodiments, vibration isolators 130 may be tunable/selected in order to achieve isolation from damaging vibration. For example, the plurality of vibration isolators 130 are tuned to a system natural frequency below a damage range associated with the one or more objects 120. For example, because vibration amplitudes are attenuated for frequencies greater than 1.4 times the system natural frequency, certain embodiments tune the inner box 110 (including its contents) to have a natural frequency less than 70% of the lowest frequency to be attenuated.
A vibration isolator 130 may be tuned in any suitable manner. Tuning may be performed at least in part by selecting a suitable number of vibration isolators 130, angle of orientation of vibration isolators 130, attachment point of vibration isolators 130, and so on. Additionally, or in the alternative, when using wire rope isolators, HERMs, or the like as vibration isolators 130, tuning can include selecting loop spacing, loop diameter, wire thickness, number of wires (e.g., if the loops are made of a rope braid), number of loops, and so on. As an example, as the weight of the inner box 110 (including its contents) increases, the wire rope isolator or HERM may be tuned to accommodate the weight (e.g., by changing wire thickness and/or number of loops, decreasing loop diameter, etc.). Similarly, when using springs (e.g., helical springs) or the like as vibration isolators 130, tuning can include selecting free length, outer diameter, wire thickness, number of turns, and so on. Embodiments using multi-stage isolators may be tuned to provide multiple stages of vibration isolation.
In certain embodiments, each vibration isolator 130 is tuned such that a force-displacement dynamic of said vibration isolator 130 is within a pre-determined tolerance of a force-displacement dynamic of the other vibration isolators 130. To achieve substantially the same force-displacement dynamic, the vibration isolators 130 may need to be tuned separately, depending on their position within system 100. For example, depending on their position within system 100, certain vibration isolators 130 may tend to experience heavier loading and may therefore be tuned to support more weight than other vibration isolators 130. Alternatively, in other embodiments, vibration isolators may all be the same type of isolator (e.g., the same model of isolator with the same tuning properties).
In certain embodiments, a cushioning material/structure, such as a foam material/structure can be positioned through a space formed by loops of a vibration isolator 130 (e.g., for a vibration isolator 130 comprising a coil structure, a foam structure can be placed through the space at the core of the coil). The cushioning material/structure acts as a safety stop to provide impact attenuation and prevent vibration isolator 130 from crimping or creasing in the event of a drop or similar impact. In certain embodiments, the cushioning structure/material may be made of a material that is soft and cushy in low-impulse environments (e.g., impulses due to vibrations) and that stiffens in high-impulse environments (e.g., impulse due to dropping case 200). Examples include an impact-responsive, variable stiffness foam such as smartfoam, urethane foam (for example PoronXRD urethane), or other material that can compress rapidly and form chemical crosslinks that stiffen and absorb energy in high-impulse environments. The cushioning material/structure may have any suitable shape, such as a block shape, a cylindrical shape, or, more generally, a mass of foam. In certain embodiments, the width/diameter of the cushioning material/structure is approximately half of the diameter of a loop of the vibration isolator 130. This may allow some air space for vibration isolator 130 to flex in low-impulse environments without engaging the cushioning material/structure. In certain embodiments, each vibration isolator 130 can be configured with a cushioning material/structure as a safety stop.
A cover may refer to any component suitable for opening and closing a box. In certain embodiments, one or more of covers 107 may be fully detachable (to open the outer box 105) and re-attachable (to close the outer box 105) and/or one or more of covers 112 may be fully detachable (to open the inner box 110) and re-attachable (to close the inner box 110). For example, the system 100 may include a plurality of latches to facilitate detaching and attaching covers 107 and/or 112. Alternatively, in certain embodiments, one or more covers 107 or 112 may be arranged as a door. As an example, cover 107 may connect to a top, bottom, left, or right wall of the outer box 105 via a hinge mechanism that allows cover 107 to be used as a door for accessing the inside of the outer box 105. Similarly, cover 112 may connect to a top, bottom, left, or right wall of the inner box 105 via a hinge mechanism that allows cover 112 to be used as a door for accessing the inside the inner box 105. Alternatively, in certain embodiments, cover 107/cover 112 may simply be a wall of the outer box 105/inner box 110 comprising a cutout that frames a door integrated on that wall. In certain embodiments, covers 107 and 112 may be arranged to allow the inner box 110 to be loaded and unloaded while in the upright position. Loading in the upright position may allow for safer and more efficient handling of objects 120, including the option of loading objects 120 from both the front and the back of the inner box 110.
For any of the types of covers 107 or 112 discussed above, certain embodiments may include one or more gaskets, such as one or more bead gaskets, which may be positioned at the seams of the opening where the cover 107/112 (or a door portion of the cover 107/112) attaches to the outer box 105/inner box 110. In this manner, the gasket may provide a water resistant seal that prevents moisture and debris from getting into the outer box 105/inner box 110 when the cover 107/112 is closed. One or more guides (such as spring-loaded alignment snaps) can be included in order to facilitate aligning cover 107/112 when closing the outer box 105/inner box 110. One or more locks and/or latches can be included to hold covers 107/112 in a closed position. In certain embodiments, the latches provide a water resistant and/or vapor resistant seal. Locks provide security by reducing the likelihood of an unauthorized person obtaining access to the contents the outer box 105 and/or the inner box 110. Examples of locks include camlocks, push button locks, keyed locks, combination locks, digital or radio frequency identification (RFID) locks, or other security mechanism.
In certain embodiments, a mounting system comprises a first mounting board 114a and a second mounting board 114b. Using two mounting boards 114 facilitates mounting objects 120 on two sides of inner box 110 (e.g., front and back). As shown in the example embodiment of
In certain embodiments, mounting surface 116 may have a rectangular shape (e.g., a generally four-sided surface in which the sides can all be the same length, such as a square, or different lengths, such as an oblong rectangle, and the corners can be perpendicular, rounded, or beveled). Objects 120 may be secured to a mounting surface 116 using one or more securing mechanisms, such as mounting bolsters 140 described below with respect to
The properties of a mounting board 114 may be selected to improve the vibration-isolating properties of system 100. Examples of such properties include material, dimensions, mass, stiffness, modulus of elasticity, and positioning within the inner box 110 (e.g., orientation of mounting board 114, spacing between first and second mounting boards 114a and 114b, spacing between first mounting board 114a and front cover 112a, spacing between second mounting board 114b and back cover 112b, etc.).
Certain embodiments dimension each mounting board 114 so that it is large enough to carry one or more objects 120, but not so large as to become cumbersome to transport. Example dimensions of mounting board 114 may be in the range of approximately 12 inches to 120 inches in length, approximately 12 inches to 120 inches in height, and approximately 0.25 inches to 6 inches in width. However, other dimensions could be used, depending on materials used and the object(s) 120 to be carried. Mounting boards 114 may have sufficient mass to ensure the vibration isolators 130 are able to provide sufficient vibration damping. For example, vibration isolators 130 may be tuned to reduce vibrations for a load having a mass within a particular range. The mass of mounting boards 114 may be selected so that the overall mass of the components suspended by the vibration isolators 130 (e.g., the inner box 110 comprising the mounting system loaded with objects 120) satisfies the tuning of the vibration isolators 130. In an embodiment, mounting board 114 comprises a 48″×48″ plywood board weighing approximately 30 pounds.
A mounting board 114 may comprise any suitable material, such as wood, aluminum plate, light-weight aluminum honeycomb, plastic, cardboard, etc. In an embodiment, each mounting board 114 comprises a sheet of plywood. Wood may be selected to moderate humidity changes within inner box 110. In certain embodiments, a mounting board 114 may comprise a first material that provides structure and a second material that provides a mounting surface 116. As an example, a mounting board 114 may comprises a wood panel with a mounting surface 116 made of a metallic material and/or a magnetic material, such as a sheet steel plate.
Spacing the mounting boards 114a and 114b by a distance may raise the natural frequency/increase the stiffness of mounting boards 114a and 114b, which may in turn improve the vibration-isolation properties of system 100. For example, modeling performed on a single plywood mounting board 114a with dimensions 60″×48″×⅜″ and supported at its corners yielded a natural frequency of 7 Hz. The modeling showed that adding a second mounting board 114b of the same type and spacing mounting boards 114a and 114b apart increased the natural frequency of both mounting boards 114a and 114b to 31 Hz when spaced by 25 mm (or approximately 1 inch), to 80 Hz when spaced by 89 mm, and to 113 Hz when spaced by 140 mm. Modeling of an aluminum plate mounting board 114 of the same size yielded analogous results (e.g., the natural frequency of a single aluminum plate was 8 Hz, and the natural frequency increased by adding a second aluminum plate spaced apart from the first aluminum plate).
Thus, certain embodiments tune the distance between mounting boards 114a and 114b to improve vibration-isolation properties of system 100. In an embodiment, a minimum distance between mounting boards 114a and 114b is at least 25 millimeters, such as at least 50 mm, at least 75 mm, at least 100 mm, at least 125 mm, or at least 150 mm. Additionally, certain embodiments may set a maximum distance between mounting boards 114a and 114b. As examples, mounting boards 114a and 114b may be separated by no more than 300 mm, no more than 275 mm, no more than 250 mm, no more than 225 mm, no more than 200 mm, or no more than 175 mm, depending on the embodiment. In certain embodiments, the distance between mounting boards 114a and 114b yields a natural frequency of the first mounting board 114a and the second mounting board 144b greater than or equal to a particular frequency, such as at least 30 Hz, 40 Hz, 50 Hz, 60 Hz, 70 Hz, 80 Hz, 90 Hz, 100 Hz, 110 Hz, 120 Hz, or other suitable frequency. Certain embodiments select the distance between mounting boards 114a and 114b to achieve a stiffness that provides a first natural frequency of the inner box clearly above the range of frequencies to be attenuated. As an example, to attenuate frequencies in the range of 10-50 Hz, the first natural frequency of the inner box 110 (with art) may be tuned to be above 100 Hz (e.g., certain embodiments select the distance between mounting boards 114a and 114b to yield a natural frequency of the first mounting board 114a and the second mounting board 144b in the range of 100 Hz to 150 Hz). Although
Certain embodiments further improve vibration-isolation properties of system 100 by optimizing the placement and orientation of each vibration isolator 130 relative to the outer box 105, the inner box 110, and/or other vibration isolators 130. In general, vibration isolators 130 may be arranged such that the inner box 110 may be made self-centering within the outer box 105. For example, vibration isolators 130 can be configured to minimize the extent to which the inner box 110 carrying object(s) 120 moves from its initial position in response to vibration and/or shock impinged on the outer box 105.
The initial position of the inner box 110 can be referred to as point (0, 0, 0) relative to the x-axis, y-axis, and z-axis. Return of the inner box 110 to the initial position (0, 0, 0) can be optimized by arranging vibration isolators 130 to oppose one another. For example, the embodiment of
In certain embodiments, the suspension system may be configured such that each vibration isolator 130 is in a state of slight compression or tension when the inner box 110 is in its initial position (0, 0, 0). Thus, the suspension system can respond to movements that cause one vibration isolator 130 to undergo increased compression without immediately causing the opposing vibration isolator 130 to undergo tension.
As described above, the vibration isolators allow for some amount of movement and re-centering of the inner box 110. While this movement helps to reduce vibrations when system 100 is in transit, the movement may make it difficult to load objects 120 in system 100 prior to transit or to unload objects 120 from system 100 once system 100 has reached its destination. To address this, certain embodiments of system 100 further comprise a loading mechanism adapted to hold the inner box 110 (including the mounting system) steady when in a first mode, such as when a technician is loading or unloading objects 120. For example, the loading mechanism may cause the vibration isolators 130 to disengage (e.g., by stiffening the vibration isolators 130, disconnecting the vibration isolators 130, and/or connecting a structure that steadies the inner box 110). The loading mechanism is further adapted to engage the plurality of vibration isolators 130 when in a second mode, such as when system 100 is in transit and would benefit from vibration isolation. Certain embodiments further comprise a stopper that prevents at least one of the outer box 105 or the inner box 110 from closing or locking when the loading mechanism is in the first mode. By preventing closing and/or locking of one or both boxes, a technician may be alerted to a problem (i.e., that system 100 is not ready to be transported because the vibration isolators 130 have not yet been engaged).
The attachment points of vibration isolators 130 to the inner box 110 affect the vibration-isolation properties, as further explained with respect to
For purposes of the modeling, an outer box 105 was exposed to various vibration models in order to analyze the effect on an inner plate to be isolated from vibration. Each vibration model included an x-parameter (indicating a number of nodes in the horizontal/x-direction), a y-parameter (indicating a number of nodes in the vertically-direction), and an s-parameter (indicating a mode shape parameter: elliptic paraboloid, hyperbolic paraboloid, or beam mode). The modeling included the following variations:
Without proper vibration isolation, exposing the outer box 105 to vibration causes the inner plate to respond in a manner somewhat analogous to a guitar string that has been plucked. That is, the inner plate will vibrate such that at a particular moment, some portion of the inner plate may move outward while another portion of the inner plate may move inward.
The observation that the corners of the inner plate exhibited a relatively high amount of movement held true for the other models, as indicated by
Similarly,
Note that in order to sum the models as described with respect to
Certain embodiments select the attachment points for vibration isolators 130 based on the modal response. For example, in certain embodiments, each of the plurality of vibration isolators 130 attaches to the inner box 110 at a respective attachment point, and each attachment point avoids locations for which a modal response associated with the location exceeds a threshold. In other words, certain embodiments select the attachment points for vibration isolators 130 such that the modal response is below a threshold. Continuing with the example of
System 100 may include any suitable number of vibration isolators 130, depending on the embodiment (e.g., one vibration isolator 130, two vibration isolators 130, three vibration isolators 130, four vibration isolators 130, etc.). Certain embodiments may use four vibration isolators (e.g., two pairs of diagonally opposed isolators, such as shown in
As described above, certain embodiments may focus one or more vibration isolators 130 on the center of gravity of the inner box 110. Orienting the vibration isolators 130 toward the center of gravity may improve the vibration-isolation properties of the vibration isolators 130. In certain embodiments, the center of gravity of the inner box 110 may be determined based on the components of the inner box 110 in a closed arrangement, including its covers 112a and 112b and the mounting system within the inner box 110 (e.g., mounting boards 114). As further described below with respect to
In certain embodiments, the plurality of vibration isolators 130 comprises at least one multi-stage vibration isolator. A multi-stage vibration isolator is adapted to provide at least a first mode of vibration isolation in response to a first vibration amplitude and to provide a second mode of vibration isolation in response to a second vibration amplitude. For example, in certain embodiments, the second vibration amplitude is greater than the first vibration amplitude (e.g., the first vibration amplitude yields lower level vibration and the second vibration amplitude yields greater level vibration). In response to the greater level vibration, the second mode of vibration isolation is more rigid than the first mode of vibration isolation. Optionally, the multi-stage vibration isolator may provide additional modes of vibration isolation, such as a third mode of vibration isolation in response to a third vibration amplitude that is greater than the first vibration amplitude and the second vibration amplitude.
In certain embodiments, a third vibration amplitude causes greater displacement that may trigger a third mode of vibration isolation. In the example of
The multi-stage stiffness described above 1) allows very low stiffness for good isolation of low amplitude, low frequency vibration, 2) prevents the occasional high amplitude vibration from causing the inner box 110 to collide with the outer box 105, and 3) prevents the system from going solid (because a solid system would be capable of transmitting very high frequencies).
In certain embodiments, the multi-stage vibration isolator further comprises a third vibration isolation mechanism (illustrated as the polymer in
In certain embodiments, the multi-stage vibration isolator comprises a washer, such as a steel washer. The washer may provide a better wear surface than the polymer and thus may be positioned to protect the polymer from wear.
The mounting bolster 140 illustrated in
As shown in the embodiments of
To facilitate the sliding of pad 146, pad 146 may comprise one or more retaining screws 148 that allow for coupling pad 146 to one or more channels 144 formed in one or more sides of structure 142. In certain embodiments, the pad 146 is adapted to be locked into a position by turning the retaining screw 148 such that the retaining screw 148 securely engages channel 144. Similarly, the pad 146 is adapted to be released from a position by turning the retaining screw 148 such that the retaining screw 148 disengages from channel 144. In certain embodiments, channel 144 may comprise a T-slot channel, and retaining screw 148 engages/disengages a T-nut positioned in the channel 144. In certain embodiments, pad 146 may be designed to be secured and released using a torque wrench. Using a torque wrench may help a technician to confirm that pad 146 is locked securely in place. As an example, all fasteners (e.g., retaining screws 148) could use the same torque (which could be an adjustable/calibrated/pre-set torque value), and the torque wrench may make a clicking sound to indicate when the fasteners are locked securely in place. In an embodiment, the torque wrench is a pre-set “T” handle slip type torque wrench that automatically releases and resets upon reaching the pre-set torque value.
In certain embodiments, pad 146 may comprise an L-plate with a tang that fits within the channel 144 (e.g., T-slot channel) to keep the plate in an orientation suitable to hold object 120 in place. The pad 146 can be inverted to accommodate the extremes of art frame sizes. For example,
In certain embodiments, a mounting bolster 140 may have a double-layer design. As an example, the corner-shaped mounting bolster 140 illustrated in
In certain embodiments, a mounting bolster 140 comprises a positioning mechanism. The positioning mechanism allows for moving object 120 to any suitable position on mounting surface 116. In certain embodiments, the positioning mechanism allows for moving mounting bolster 140 horizontally (in the direction of the x-axis), vertically (in the direction of the y-axis), and diagonally (in any other direction in the x-y plane). For example, instead of using racks, channels, or similar structures that may constrain the movement of mounting bolster 140, the positioning mechanism may comprise one or more magnets, Velcro, or other mechanisms that permit a full range of movement along mounting surface 116. In this manner, mounting bolsters 140 can be positioned to accommodate various sizes of objects 120 (e.g., a set of four corner-shaped mounting bolsters 140 can be placed relatively close together to accommodate a smaller painting and relatively far apart to accommodate a larger painting). Additionally, mounting bolsters 140 can be positioned so that objects 120 are located in an optimal position on mounting surface 116. In certain embodiments, the optimal position accommodates multiple objects 120 on the same mounting surface 116. In certain embodiments, the optimal position allows for positioning objects 120 such that the overall mass of the inner box 110 (including its contents) is centered at the isolator focal point in order to decouple system 100's vibration response.
In certain embodiments, the positioning mechanism can be arranged in a first mode or a second mode. When the positioning mechanism is arranged in the first mode, the positioning mechanism is adapted to facilitate moving the mounting bolster 140 in any direction along the mounting surface 116. When the positioning mechanism is arranged in the second mode, the positioning mechanism is adapted to facilitate locking the mounting bolster 140 into a fixed position on the mounting surface 116.
The examples of
In certain embodiments, mass units can be added to lower the system natural frequency and to ensure that the CG is at the isolator focal point. Thus, the mass units compensate for objects 120 having too little mass (e.g., if paintings carried by the inner box 110 are lighter than the mass to which vibration isolators 130 have been tuned). In certain embodiments, mass units can be mounted to a mounting board 114, for example, using mounting bolsters 140. In addition, or in the alternative, one or more mass units may be attached to an interior surface and/or an exterior surface of the inner box 110. Each mass unit can have a standardized or specified mass to simplify calculating the mass added by the mass units. In certain embodiments, the mass units are aluminum units containing phase change material to help maintain a stable temperature inside the inner box 110. In certain embodiments, the mass units 117 comprise inelastic particulate, such as lead shot, which may help damp vibrations. In some embodiments, the inelastic particulate may be suspended in gel. Alternatively, the inelastic particulate may be surrounded by air.
If the inner box 110 is not centered or is not loaded with sufficient mass, the inner box 110 may experience sway up to several inches in any direction. To minimize sway, it is important that the mass of the inner box 110 (including its contents) matches the mass to which the vibration isolators 130 are tuned, and that the CG of the inner box (including its contents) is centered at the isolator focal point. As an example, suppose vibration isolators 130 are tuned to a fixed mass of 90 kilograms such that vibrations in the critical range (e.g., 8-40 Hz) are not transmitted to objects 120 when the mass of the inner box (including its contents) is approximately 90 kilograms and centered. More generally, to effectively attenuate transmission of a specific range of vibrations, the mass should be matched with the tuning of the vibration isolators 130 (in other words, vibration isolators 130 should be tuned to the mass of the components suspended by vibration isolators 130).
As an example, the vibration-isolating system may be adapted to carry one or more paintings (e.g., stretched canvas painted with artwork). In certain embodiments, vibration isolators 130 may be tuned to attenuate vibrations in a pre-determined frequency range for a payload having a pre-determined mass. The pre-determined frequency range in turn determines the required natural frequencies of the system as well as the inner and outer box structures. The inner box 110 then vibrates with reduced amplitude and as a rigid solid thereby reducing the stress on the canvas and reducing the tendency for vibration at the art work's resonant frequencies (e.g., first, second or third drum frequencies of the canvas). In certain embodiments, the pre-determined frequency range to be damped begins at approximately 8-10 Hz and ends at approximately 40-50 Hz, such as 8-40 Hz, 8-50 Hz, 10-40 Hz, or 10-50 Hz, among others. In certain embodiments, the pre-determined mass is between 80-100 kilograms, such as 90 kilograms.
Suppose the vibration isolators 130 are tuned to attenuate vibrations in the pre-determined frequency range of 10-50 Hz for a payload having a pre-determined mass of 90 kilograms. The system natural frequency should be less than 7 Hz. Suppose the inner box 110, including its covers 112, mounting boards 114, and mounting bolsters 140, weighs 50 kilograms. As a first example, suppose loading the painting(s) plus any optional mass units adds 35 kilograms such that the combined mass of the components suspended by vibration isolators 130 is 85 kilograms. The mass of 85 kilograms causes the natural frequency to be increased to 7.2 (fn2=fn1*sqrt(m1/m2)) Hz. The system is designed for the minimum anticipated weight. Any weight more than this is guaranteed to be sufficiently isolated from vibrations as the system natural frequency will decrease with additional mass leading to more attenuation. The maximum mass is determined by the isolator force/displacement curve.
In other embodiments, different vibration isolators 130 could be specified (e.g., wire thickness, number of loops, loop diameter, loop spacing, and/or number of wires in a rope braid could be adjusted) in order to tune the isolators to attenuate vibrations in the pre-determined frequency range of 10-50 Hz for a payload having a different pre-determined mass, such as 50 kilograms for a smaller case or 120 kilograms for a larger case, or other suitable value. Similarly, in other embodiments, different isolators 130 could be specified (e.g., wire thickness, number of loops, loop diameter, loop spacing, and/or number of wires in a rope braid could be adjusted) in order to tune the isolators to attenuate vibrations in a different pre-determined frequency range, depending on the resonant frequency of objects 120.
As discussed above, certain embodiments suspend an inner box 110 by four vibration isolators 130 (which may be arranged as described above with respect to
The various components described throughout this disclosure may be combined to form a vibration isolation system. The vibration isolation system may use any suitable combination of components, such as outer box 105, covers 107, inner box 110, covers 112, mounting boards 114, objects 120, mass units, vibration isolators 130, mounting corners 140, and/or other components. Examples of other components include one or more sensors that may optionally be mounted in or on outer box 105, inner box 110, mounting board 114, or object 120. Sensors may monitor and record vibrations and shocks occurring during transit, pressurization conditions, environmental conditions, GPS coordinates, surveillance cameras, and/or other suitable information. Additional examples of other components include humidity buffers, thermal controls (e.g., insulation materials, heating and cooling units, etc.), or other components selected to maintain optimal environmental conditions within inner box 110. Optionally, system 100 may be configured with one or more shock absorbing structures to absorb impact and prevent damage to objects 120 in transit. For example, in certain embodiments, one or more of the shock absorbing structures may compress or collapse quickly in the event of a shock (such as a drop or collision) and expand slowly after the shock to reduce rebound movement of inner box 110. In addition, or in the alternative, certain shock absorbing structures compress quickly in the event of a shock (such as a drop or collision) but do not decompress. Using a material that does not decompress may avoid rebound movement. If the structure remains compressed, it can be used as an indicator to identify whether system 100 was handled improperly. Examples of shock absorbing structures include replaceable structures composed of paper (e.g., honeycomb, fluted, and/or corrugated shaped structures), polypropylene, polycarbonate, polystyrene (e.g., closed cell expanded polystyrene (XPS) core), open cell polyurethane foam (smartfoam, Poron XRD, D30 and similar), and/or any suitable combination of the preceding.
Certain examples throughout this disclosure describe mounting surface 116 as positioned in a vertical orientation when system 100 is in a stationary and upright orientation. Other embodiments may position mounting surface 116 in any other suitable orientation, such as a horizontal orientation.
Certain embodiments of the present disclosure may provide one or more technical advantages. Certain embodiments may protect an object from damage due to vibrations, displacement, impact, temperature, and/or humidity. As discussed above, any suitable combination of the components described herein can be used to provide the desired protections.
Certain embodiments may have all, some, or none of the above-identified advantages. Other advantages will be apparent to persons of ordinary skill in the art.
Modifications, additions, or omissions may be made to the systems and apparatuses described herein without departing from the scope of the disclosure. The components of the systems and apparatuses may be integrated or separated. Moreover, the operations of the systems and apparatuses may be performed by more, fewer, or other components. Modifications, additions, or omissions may be made to the methods described herein without departing from the scope of the disclosure. The methods may include more, fewer, or other steps. Additionally, steps may be performed in any suitable order.
Although this disclosure has been described in terms of certain embodiments, alterations and permutations of the embodiments will be apparent to those skilled in the art. Accordingly, the above description of the embodiments does not constrain this disclosure. Other changes, substitutions, and alterations are possible without departing from the spirit and scope of this disclosure, as defined by the following claims.
