Measuring and testing – Vibration – Vibrator
Reexamination Certificate
2000-03-28
2002-11-05
Kwok, Helen (Department: 2856)
Measuring and testing
Vibration
Vibrator
C073S666000
Reexamination Certificate
active
06474167
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to a mechanical amplifier for a vibrational testing device and, more particularly, to a series of mechanical amplifiers used in connection with a shaker, where the amplifiers employ a spring.
2. Discussion of the Related Art
Performance testing of various structures is important to insure that the structures meet load and force requirements for a specific purpose. Therefore, it is known to employ shakers to provide vibrational tests of various structures and components, such as spacecraft and electronic components. One particular shaker used for this purpose is the T4000 shaker system available from Uniholtz-Dickie.
In one known performance test, it is necessary to test the spacecraft structure to 8 g's in an axial configuration. The spacecraft structure, including mass simulators, weighs approximately 5800 pounds. The moving mass of the T4000 shaker system weighs approximately 1700 pounds. Therefore, the ability to accelerate 7500 pounds to 8 g's at 25 Hz is required for a particular vibrational test. This corresponds to approximately 0.25 inches peak-peak displacement and 60,000 pounds of force. However, the T4000 shaker system can only generate 40,000 lbs peak load, and thus is not able to provide the desired input.
Various solutions can be used to meet the necessary testing requirements in this example. These solutions include using a larger shaker system, combining two or more smaller shaker systems, or reverting to static or component level testing. Static or component level testing tends to be labor intensive, and thus is not a desireable alternative. Using a larger shaker system requires that the shaker system be purchased at a very significant cost. Additionally, combining two or more shakers requires suitable fixtures and the like for combining the shakers. The fixtures necessary to combine two or more shakers to meet the testing load capacity would be labor intensive, and also require significant development costs beyond the cost of the actual shaker systems. Also, using larger shaker systems, or combining two more shaker systems increases the space necessary to provide the test.
What is needed is a technique for increasing the vibration capacity of an existing vibrational shaker, without having to incur significant costs. It is therefore an object of the present invention to provide such a shaker system.
SUMMARY OF THE INVENTION
In accordance with the teachings of the present invention, a shaker system is disclosed that employs one or more mechanical amplifiers for increasing the vibrational capacity of the shaker. The mechanical amplifier includes a spring positioned within a support column, where the spring is attached to an interface ring supporting the load to be tested at one end and the ground at an opposite end. The spring can take on different configurations, and in one embodiment is a sinusoidal spring having half-circle sections of a predetermined radius thickness and width which satisfies the resonant frequency requirements for a particular load. The resonant frequency of the spring causes the vibration to be amplified, meeting the testing requirements.
Additional objects, advantages and features of the present invention will become apparent from the following description and appended claims, taken in conjunction with the accompanying drawings.
REFERENCES:
patent: 3945246 (1976-03-01), Wadensten
patent: 4428238 (1984-01-01), Tauscher
patent: 5083463 (1992-01-01), Marshall et al.
patent: 5517857 (1996-05-01), Hobbs
patent: 5594177 (1997-01-01), Hanse
patent: 5969256 (1999-10-01), Hobbs
Harness & Dickey & Pierce P.L.C.
Kwok Helen
TRW Inc.
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