The Design Method And Test Method Study Of Vibration Test Fixture Of Locomotive Electrical Equipment

Abstract:The purpose of the vibration test is to find various defects in design and manufacturing process of the equipment, and to verify the adaptability in vibration environment and the reliability in design life. Vibration can cause structural cracks, fracture, loose of the fasteners, electrical short-circuit, seal failure, structural dynamic displacement and other types of failure. According to statistics,40%of early American missile accidents was caused by vibration. Up to52%failure was inspired by vibration in railway transportation equipment tests. We can see that vibration is the significant factor which affected the useful life of equipment and work performance. With the high-speed and heavy load development of rolling stock, vibration environment has become increasingly harshness. The vibration test must be performed according to the standard, which played a vital role in verifying eligibility and reliability of the products, and in guaranteeing vehicles safe operation. The fixture is a key component of the vibration test, and its main function is to transforming the real movement of the vibration table to the product, which plays an extremely important role in vibration test. For unreasonable fixture design, manufacture and installation may be prone to "over-test" and "under-test, the vibration test fixture must be in-depth study. Due to the situation that IEC61373did not put forward specific requirements in fixture, and railway transportation rarely has research in fixture, in this paper, a systematic study has be made in vibration fixture of the locomotive electrical equipment.In this paper, we induced9types of vibration test fixtures by studying on more than200fixtures, analyzed its common materials and performance, and expounded6kinds of manufacturing process method and their characteristics, proposed design and installation methods of base-mounted and hung-mounted universal fixture. We built its dynamical model, reduced the transfer rate of the fixture and its expression of resonance magnification factor, obtained the relationship between the transfer rate and the coefficient divided the natural frequency of the fixture by the upper frequency of the test, analyzed the influence of the damping on the resonance magnification factor, provided theoretical basis for the optimal design of a typical fixture. Then we designed the universal fixture used the conclusion of theoretical analysis, and analyzed its modal by the finite element method and experimental modal method before and after the improvement of the fixture, set up a fixture modal test system with the core of electrical vibration table, and measured the first five natural frequencies by the sine sweep method, and verified the eligibility of the improvement of the typical fixture and the method of analysis by model simulation vibration test.