Bonded materials are used in a variety of structural applications. For example, adhesively bonded, laminated composite structures are increasingly being used in aircraft construction to reduce weight, reduce or eliminate the number of separate components, reduce fabrication costs, and improve fuel efficiency. The presence of material defects in a composite aircraft structure can lead to disastrous failure of the structure under flight loads. These defects may exist in the composite laminate itself, as well as in the adhesive bonds in the structure. The defects may arise as a result of damage during service, or in the original manufacturing process.
The growing ubiquity of composite structures has led to an increased need for techniques to evaluate the strength of the composite structures, including the adhesive bonds themselves, without damaging or destroying the composite structures. Conventional nondestructive evaluation (“NDE”) techniques are useful when a gap, crack, or void is present in a bonded material. However, conventional NDE techniques do not adequately identify deficiencies, such as weak bonds or “kissing bonds,” where materials bonded together are in contact but without adequate structural strength. These deficiencies can result from bond surface contamination, improperly mixed or outdated adhesives, improper adhesive curing, and improper adhesive application.
Laser bond inspection (“LBI”) is an NDE technique for testing the integrity of bonded materials and structures. LBI comprises sending a precisely controlled dynamic stress wave through an adhesive bond of a composite structure. Generally speaking, and with reference to
Current LBI equipment is large, and the bonded article must either be positioned to align with the LBI equipment or the LBI equipment must be manually positioned vis-a-vis each bond prior to inspection. While manual positioning of the bonded article and LBI equipment is acceptable for relatively small, bonded parts, the use of such LBI techniques is more challenging with larger structures such as aircraft wings, fuselage components, wind turbine blades, bridge and building structures, and the like. U.S. Pat. Nos. 6,288,358; 6,528,763; 6,867,390; 7,770,454; and 8,156,811 (all to LSP Technologies, Inc.), all of which are incorporated herein by reference in their entireties, disclose improvements to laser system mobility.
What is needed is an automated and dynamic system and apparatus for laser bond inspection of a bond in a bonded article.
Systems and methods are provided for automated laser bond inspection of a bond in a bonded article.
In one embodiment, a system for non-destructively inspecting a bond in a bonded article is provided, the system comprising: a laser beam delivery system operable to deliver a laser beam from a laser to a workpiece for laser bond inspection of a bonded article, and a dynamic platform system, operable to move one or more components of the laser beam delivery system in one or more axes of translation and one or more axes of rotation.
In another embodiment, an automated and dynamic system for laser bond inspection of a bond in a bonded article is provided, the system comprising: (1) a laser, the laser configured to generate a pulsed laser beam; (2) a laser beam delivery system operatively connected to the laser and operable to deliver the pulsed laser beam to at least one of: a workpiece surface, and a processing head; (3) a surface motion sensor, the surface motion sensor configured to detect a surface motion on the workpiece surface during the laser bond inspection; (4) a dynamic platform system operable to support and move one or more components of the automated and dynamic system for laser bond inspection; and (5) a control system comprising at least one of: one or more processors, and one or more controllers, wherein the control system is operable to execute an instruction set, process input and output signals, and control one or more components of the automated and dynamic system for laser bond inspection.
A method for automated non-destructive testing of a bond in a bonded article is provided, the method comprising: (1) defining coordinates of a first bond and subsequent bonds in a series of bonds and/or a first bond location and subsequent bond locations in a single bond in a bonded article; (2) automatically positioning a laser beam in relation to the coordinates; (3) lasing a surface of the bonded article with a pulsed laser beam in a low-high-low pulsed energy sequence, each pulse having a pulse energy of between about 3 J and about 50 J; (4) detecting surface motion on the bonded article; and (5) repeating steps 3-4 after repositioning the laser beam to the coordinates of a subsequent bond in the series of bonds and/or a subsequent bond location in the single bond.
In one embodiment, an automated dynamic LBI system can test composite to composite bonds, metal to metal bonds, and composite to metal bonds.
In another embodiment, an automated dynamic LBI system is self-contained and sits on a mobile platform to facilitate rapid insertion of the LBI process into manufacturing plant operations or maintenance depots.
In another embodiment, an automated dynamic LBI system is automated to inspect bonded materials with minimal manual movements providing improved test repetition, improved test accuracy, and reduced LBI operational cost.
In another embodiment, an automated dynamic LBI system is automated to both position a processing head and facilitate movement of a laser and a laser beam delivery system around a large structure, so that a processing head may be automatically positioned on different parts of a large structure without requiring movement of the large structure to position the processing head.
The accompanying figures, which are incorporated in and constitute a part of the specification, illustrate example systems and methods, and are used merely to illustrate example embodiments.
The embodiments claimed herein disclose using an automated dynamic laser bond inspection system for inspecting a bond in a bonded article. With reference to
In one embodiment, laser 220 may comprise, for example, a neodymium glass laser, such as, for example, those manufactured by LSP Technologies, Inc., a YAG laser, a YLF laser, or any other solid-state crystal material, in either a rod or a slab gain medium. Laser 220 may be configured to deliver laser pulses having a pulse energy of between about 3 J and about 50 J (at the output of the final amplifier module), a wavelength of about 1 μm, and a pulse width of between about 100 ns and 300 ns, and further being configured to deliver the laser pulses in a low-high-low or probe-break-probe pulse energy sequence (i.e., a first laser pulse have a first energy, a second laser pulse having a second energy that is greater than the first energy but less than an energy required to break a properly constructed or “good” bond, and a third laser pulse having an energy which is approximately the same as the first pulse's energy), as described and illustrated in U.S. Pat. Nos. 7,770,454 and 8,156,811. LBI uses a laser pulse width of about 70 ns to about 300 ns. Beam diameter of LBI is selected as a compromise between the need to have a large area for planar wave generation and a reasonable sized beam for the inspection of small zones in the object. A beam size of about 10.0 mm is a suitable compromise. The use of a large diameter laser beam of several mm or more generates suitable internal stress for the evaluation of internal bonds and avoids surface spallation of a bonded article under LBI. Fluence is a measure of energy delivered per unit area, and LBI uses fluence values ranging between about 4 J/cm2 to about 6 J/cm2 for the interrogation of weak bonds, while medium strength bonds fail around about 16 J/cm2. Further configurations of laser 220 may include those described and illustrated in U.S. Pat. Nos. 7,770,454 and 8,156,811.
In one embodiment, laser beam delivery system 230 may comprise, for example, at least one of: (a) one or more mirrors; (b) an articulated arm; and (c) one or more fiber optics (also referred to as an optical fiber), and includes the laser beam delivery systems described and illustrated in U.S. Pat. Nos. 7,770,454 and 8,156,811. In one embodiment, where laser beam delivery system 230 is one or more mirrors, the beam may be directed to the surface of bonded article 210 without need for processing head 240. In alternative embodiments, where laser beam delivery system 230 is an articulated arm and fiber optics, laser beam delivery system 230 may be operatively connected to processing head 240.
In one embodiment, surface motion sensor 250, such as an EMAT coil, may be integrated in processing head 240. In another embodiment, surface motion sensor 250 may be separate from processing head 240 like a remote optical interferometer such as a VISAR device. In another embodiment, surface motion sensor 250 may be a Doppler velocimeter.
Additionally, processing head 240 may include a first output (not shown) to output a laser beam if processing head is operatively connected to laser beam delivery system 230, and second output (not shown) to output one or more overlays such as: a transparent overlay, an opaque overlay, an inspection coupon, a metal foil. Processing head may include one or more suction ports (not shown) to vacuum debris generated during a laser bond inspection process proximate to processing head 240 and workpiece surface, and be used for vacuum attachment of processing head 240 to a workpiece.
Laser feedback sensor 222, laser beam delivery feedback sensor 232, and processing head sensor 242 may provide feedback to control units, e.g., control units 472 and 474, as depicted in and described herein with respect to
With reference to
With reference to
Chassis 462 contains one or more movement devices 464. Movement devices 464 may be one of: a wheel; a continuous track caterpillar tread; a railroad bogie or the like, and may be suited to a specific application of dynamic platform 400. In one embodiment, movement device 464 may interface with one of: a rail system, a track, and a guide in a floor or mounted on the wall and ceiling of a facility such that dynamic platform 400 is guided around the facility via rail, track, and guide. In one embodiment, movement device 464 may be operatively connected to drive source 470. In one embodiment, movement device 464 is a combination of pivotable steering wheels and fixed drive wheels connected to an electronic control unit (ECU) 472 which controls power from drive source 470 to each drive wheel to provide dynamic platform 400 with a low turning radius steering capability. A dynamic platform 400 with a low turning radius is advantageous for use in a manufacturing facility or maintenance depot where space concerns may require precise turning and increased maneuverability.
Dynamic platform 400 is intended for automated operation in conjunction with an LBI system, e.g., LBI system 200. A control system for controlling dynamic platform 400 may include one or more controllers 472, 474, and one or more processors (not shown). Control system may be operable to execute an instruction set (i.e. programs), process input and output signals (i.e. from sensors), and control one or more components of the automated and dynamic system for laser bond inspection. Controllers 472, 474 may be controllers used in process control such as a programmable logic controller (PLC). In one embodiment, ECU 472 may be programmed to provide automated operation of dynamic platform 400 and LBI 200. Additionally, ECU 472 and one or more control units 474 may be programmed to provide specific automation functions such as laser control, laser beam delivery control, articulated arm control, processing head control, lift control, steering control, drive source control, etc. ECU 472 and one or more control units 474 may be selected from con In one embodiment, all automation is controlled by ECU 472. In another embodiment, one or more control units 474 may be used to control each specific automated function. Control units 472 and 474 may be electrically connected to other devices on dynamic platform 400 by a bus system 476. Bus system 476 may be any communications network capable of interconnecting electrical components known in the art such as: a wire harness; a CAN Bus; D2B; I2C and the like. In one embodiment, control units 472 and 474 may be remote from, but operatively connected to dynamic platform 400 either wirelessly or by tethered connection. I
In one embodiment, control units 472 and 474 may be programmed remotely using a transceiver 478. Transceiver 478 may be operable to provide remote communication to and from control units 472 and 474. In certain embodiments, transceiver 478 provides communications to and from: a remote control; another automated device; remote feedback sensors, etc. In another embodiment, control units 472 and 474 may be programmed by a user interface (UI) 480 provided on dynamic platform 400. In one embodiment, UI 480 is a control panel of easily customizable hardware and software, such as a job-specific, customized graphical user interface on a touchscreen display to provide easy programming of both the LBI system and dynamic platform 400. In one embodiment, a user may input spatial coordinates of bonds in a bonded article by either transceiver 478 or user interface 480. In another embodiment, bonds may be identified by one or more dynamic platform feedback devices 482.
One or more dynamic platform feedback devices 482 are provided on dynamic platform 400 to provide feedback data to control units 472 and 474 to assist in automated operation. Dynamic platform feedback devices 482 are sensors used to gather feedback information to provide for proper automation control of dynamic platform 400. Dynamic platform feedback devices 482 may include, but are not limited to: spatial position sensors, location position sensors, displacement sensors, alignment sensors, tilt sensors, cameras, optical sensors, phototransitors, accelerometers, Global Positioning System (GPS), a laser beam profiler, magnetometers, gyroscopes, pressure sensors, gas sensors, voltage and current sensors, capacitive touch sensors, color detection, light detection, force sensors, infrared (IR) emitters/detectors, radio-frequency identification (RFID) sensors, potentiometers, thermistors, temperature and humidity sensors, ultrasonic rangefinders and echo location sensors, laser positioning, video imagining sensors and the like. In one embodiment, feedback device 482 may be an echo location sensor that will detect when a temporary or fixed object is in the inspection path of dynamic platform 400. In response to an output signal from feedback device 482, control units 472 or 474 may cut power from drive source 470 to movement device 464 to stop movement of dynamic platform 400 to prevent injury or damage. In another embodiment, an optical sensor that recognizes a patterned indicia may be used. For example, feedback device 482 may detect a patterned tape outline on the manufacturing facility floor around a test object and provide feedback to control units 472 or 474 for steering dynamic platform 400 around the test object by following the path of patterned indicia. In another embodiment, feedback device 482 may interface with sensors embedded within a facility wall, floor, and ceiling to guide dynamic platform 400 around the facility.
With reference to
Lifting mechanism 584 may be of any type common in the art, including, but not limited to: a scissor lift; a screw lift; one or more pneumatic, hydraulic, or mechanical actuators; a rack and pinion; a boom; a pulley system and the like.
With reference to
Unless specifically stated to the contrary, the numerical parameters set forth in the specification, including the attached claims, are approximations that may vary depending on the desired properties sought to be obtained according to the exemplary embodiments. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.
Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements.
Furthermore, while the systems, methods, and apparatuses have been illustrated by describing example embodiments, and while the example embodiments have been described and illustrated in considerable detail, it is not the intention of the applicants to restrict, or in any way limit, the scope of the appended claims to such detail. It is, of course, not possible to describe every conceivable combination of components or methodologies for purposes of describing the systems, methods, and apparatuses. With the benefit of this application, additional advantages and modifications will readily appear to those skilled in the art. Therefore, the invention, in its broader aspects, is not limited to the specific details and illustrative example and exemplary embodiments shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of the general inventive concept. Thus, this application is intended to embrace alterations, modifications, and variations that fall within the scope of the appended claims. The preceding description is not meant to limit the scope of the invention. Rather, the scope of the invention is to be determined by the appended claims and their equivalents.
As used in the specification and the claims, the singular forms “a,” “an,” and “the” include the plural. To the extent that the term “includes” or “including” is employed in the detailed description or the claims, it is intended to be inclusive in a manner similar to the term “comprising,” as that term is interpreted when employed as a transitional word in a claim. Furthermore, to the extent that the term “or” is employed in the claims (e.g., A or B) it is intended to mean “A or B or both.” When the applicants intend to indicate “only A or B, but not both,” then the term “only A or B but not both” will be employed. Similarly, when the applicants intend to indicate “one and only one” of A, B, or C, the applicants will employ the phrase “one and only one.” Thus, use of the term “or” herein is the inclusive, and not the exclusive use. See Bryan A. Garner, A Dictionary of Modern Legal Usage 624 (2d. Ed. 1995). Also, to the extent that the terms “in” or “into” are used in the specification or the claims, it is intended to additionally mean “on” or “onto.” To the extent that the term “selectively” is used in the specification or the claims, it is intended to refer to a condition of a component wherein a user of the apparatus may activate or deactivate the feature or function of the component as is necessary or desired in use of the apparatus. To the extent that the term “operatively connected” is used in the specification or the claims, it is intended to mean that the identified components are connected in a way to perform a designated function. Finally, where the term “about” is used in conjunction with a number, it is intended to include ±10% of the number. In other words, “about 10” may mean from 9 to 11.
This application claims priority from U.S. Provisional Patent Application No. 61/903,584, filed on Nov. 13, 2013, which is incorporated by reference herein in its entirety.
Number | Date | Country | |
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61903584 | Nov 2013 | US |