Patent Application
20060272435
The present invention relates generally to acceleration testing of products and/or components parts, and more specifically, to the simulation of high acceleration forces on products and/or component parts.
It is often desirable to test products and/or their component parts under conditions that are similar to those expected in the field. The test results may be used to help ensure that the products and/or their component parts will function properly in the field. For some applications, it is difficult to properly test the products and/or component parts, sometimes because of the extreme conditions for which they are intended to be used. For example, testing projectiles and/or components of such projectiles, such as circuit cards, during conditions of a ballistic event in a controlled and reproducible manner can be difficult. Similarly, testing acceleration sensors and/or cards during conditions of an automobile crash can be difficult. These are just a few examples.
The testing of components for use in a projectile would ideally include simulation of accelerative forces that are similar to those that are expected during actual service in the field. However, the associated long duration, high acceleration environment of ballistic applications, such as the firing of a gun, can typically not be adequately simulated in a laboratory environment. The ruggedness and reliability of many components generally cannot be qualitatively, quantitatively, or comparatively evaluated except under conditions which simulate their actual flight experience without the terminal destruction which would be experienced by actual flight. Not being able to simulate/test these high-g forces has presented some design challenges.
A typical method of simulating forces that are experienced by a projectile include using an “air gun” that accelerates a projectile by air pressure in a confined tube of suitable diameter. However, this and many other previous methods have a maximum force and/or duration that can be produced and simulated. For example, an air gun may be capable of producing levels up to 20,000 G's, but at these force levels, the duration of the event is typically less than a millisecond or so. For many ballistic applications, such as the firing of a gun, as well as other high-g applications, the events may extend over 10 milliseconds or more. Thus, it may be desirable to simulate relatively large forces over a relatively longer duration.
The following summary of the invention is provided to facilitate an understanding of some of the innovative features unique to the present invention and is not intended to be a full description. A full appreciation of the invention can be gained by taking the entire specification, claims, drawings, and abstract as a whole.
The present invention relates generally to the simulation of relatively high acceleration forces on components or component parts. In one illustrative embodiment, an apparatus for simulating such environments includes a test specimen, such as a circuit card, an incompressible liquid situated adjacent to the test specimen, and a device for creating a dynamic high-g event on the test specimen. In one case, the device for creating the dynamic high-g event may include a vibration actuator that creates a force between the test specimen and the liquid. The vibration actuator may create such a force by moving (e.g. vibrating) the test specimen toward the incompressible liquid. In some cases, and to help increase the force that is exerted on the test specimen in response to movement by the vibration actuator, a reaction mass may be situated opposite the incompressible liquid. In some cases, the incompressible liquid itself may function as, and/or contribute to, the reaction mass. In another illustrative embodiment, the device for creating the dynamic high-g event may be a dynamic hydraulic pressure supply that creates a pressure pulse or the like in the incompressible liquid, and toward the test specimen.
An illustrative method for simulating a high-g environment may include providing a test specimen mounted on a mounting structure, providing an incompressible liquid adjacent to one side of the test specimen, and creating a dynamic high-g force on the test specimen. In some cases, the dynamic high-g event is created by a vibration actuator that may create vibratory movement between the test specimen and the incompressible liquid. In other embodiments, the dynamic high-g event may be created by a dynamic hydraulic pressure pulse in the incompressible liquid, or in any other suitable manner.
The following description should be read with reference to the drawings wherein like reference numerals indicate like elements throughout the several views. The detailed description and drawings show several embodiments which are meant to be illustrative of the claimed invention.
The illustrative embodiment includes a test specimen 10, a mounting structure 18 for mounting the test specimen 10, an incompressible liquid 12 situated above and adjacent to the test specimen 10, and an actuator device (e.g. shaker) for creating a dynamic high-g event on the test specimen 10. In some cases, the test specimen 10 may be a printed wiring board or a circuit card, but it is contemplated that other products or components may be similarly tested. More generally, the test specimen 10 may be any specimen that is subject to relatively high-g forces, high acceleration environments, or high stress levels, as desired. In some cases, the weight of the test specimen (e.g. printed wiring board) may be in the range of one twentieth of a pound to one tenth of a pound. However, the weight of the test specimen 10 may be any weight as required or desired for the particular application at hand.
The incompressible liquid 12 may be water based, hydraulic fluid based, or any other suitable based liquid 12 as desired, including a gel form. The illustrative incompressible liquid 12 may provide a reaction force on the test specimen 10. In some cases, the reaction force may be in “reaction” to the movement of the actuator 14, as further described below. In some cases, the liquid 12 may have a surface area adjacent to the test specimen in the range of 3 to 4 square inches, but it is contemplated that any other suitable surface area may be used as desired for the simulated real world application, as well as on the size and other characteristics of the test specimen 10.
In some cases, the illustrative embodiment may include a diaphragm 26 and/or a membrane 22. In one illustrative embodiment, a diaphragm 26 may be situated on one side of the liquid 12, and a membrane 22 may be situated on the other. In some cases, the diaphragm 26 may be situated between the liquid 12 and a separate reaction mass 20, and the membrane 22 may be situated between the test specimen 10 and the incompressible liquid 12. A containment fixture 16 may be provided to help contain the liquid 12 between the diaphragm 26 and the membrane 22.
Alternatively, or in addition, the liquid 12 may be contained in a bag or the like, where the membrane 22 and diaphragm 26 are different sides of the bag. A containment fixture 16 may still be provided, if desired, to add support to the sides of the bag. The membrane 22 and/or diaphragm 26 made be made of any suitable material, such as a polymer or any other material as desired, which does not impede or substantially impede the transmission of the reaction force from the incompressible liquid to the test specimen 10.
An actuator device 14 may create a dynamic high-g event on the test specimen 10. In some cases, the actuator device 14 may be a vibration actuator, such as a shaker. The vibration actuator 14 may move the mounting structure 18 and thus the test specimen 10 toward and away from the liquid 12, thus creating a force between the test specimen 10 and the liquid 12. In some cases, the actuator device may move the incompressible liquid 12 relative to the test specimen 10 to help create a dynamic high-g event.
In one illustrative embodiment, the actuator device 14 is a shaker. The shaker may be, for example, an electro-dynamic shaker, a hydraulic shaker, a piezoelectric shaker, or any other suitable shaker, as desired. The shaker may generate, for example, about 15,000 pounds of force, about 30,000 pounds, about 50,000 pounds, or any other suitable force, as desired.
Alternatively, the actuator device 14 may be a dynamic hydraulic pressure supply. The dynamic hydraulic pressure supply may create a pulse in, for example, the incompressible liquid 12, which then presents a force on the test specimen 10. In some cases, the dynamic hydraulic pressure supply may be a high frequency dynamic hydraulic pressure supply, but this is not required.
To help increase the force experienced by the test specimen, a reaction mass 20 may be provided. In the illustrative embodiment shown in
The illustrative embodiment shown in
In some cases, the test apparatus may be opened and closed to allow the test specimen 10 to be inserted and removed. Springs, such as springs 28, may help raise the reaction mass 20. The liquid 12 may then be removed, and there may be access to the test specimen 10 and mounting structure 18 so that the test specimen 10 may be mounted and un-mounted. In some cases, the containment fixture 16 may include more than one piece including, for example, one or more guide pins 24 that are insertable into a wall of the containment structure. The guide pins 24 may be attached to an head 30 of the actuator device 14, and may help secure the containment fixture 16 to the head 30. Also, the guide pins 24 may make a more rigid support for the containment fixture 16. However, it is contemplated that any method may be used to fix and align the containment fixture 16 with the head 30.
A reaction mass 120 is provided and engages the diaphragm 126. The reaction mass 120 may add weight to the incompressible liquid 112 creating a greater force on the liquid 112 test specimen 110 interface, resulting in a higher force simulation. The reaction mass 120 may be any mass that adds weight such as a liquid, metal, plastic, or any other suitable material as desired.
In this illustrative embodiment, the dynamic hydraulic pressure supply 340 may create a dynamic high-g event. The dynamic hydraulic pressure supply 340 may be in fluid communication with the incompressible liquid 312 in such a way as to create a pressure pulse in the liquid 312. The liquid 312, being in registration and in contact with the test specimen 310, may transmit the pressure pulse to the test specimen 310. This pressure may create a force on the test specimen 310, which simulates a real world high-g event. Similar to the previous embodiments, a reaction mass, such as reaction mass 318 and 320 may be provided to add weight creating a higher pressure at the test specimen 310. The reaction mass 320 may be an incompressible liquid 312 or any other structure that is capable of acting as a reaction mass, as desired.
Having thus described the preferred embodiments of the present invention, those of skill in the art will readily appreciate that yet other embodiments may be made and used within the scope of the claims hereto attached. Numerous advantages of the invention covered by this document have been set forth in the foregoing description. It will be understood, however, that this disclosure is, in many respects, only illustrative. Changes may be made in details, particularly in matters of shape, size, and arrangement of parts without exceeding the scope of the invention. The invention's scope is, of course, defined in the language in which the appended claims are expressed.
