Research On The Simulation Of Super-gaussian Random Vibration Environment With Controllable Frequency Spectrum And Its Applications

As a very important part of equipment reliability and environmental engineering, Environmental Stress Testing must be considered throughout the whole design and production processes of the equipment. EST can find the design flaws and provide useful information for improving the reliability and environmental adaptability of the products during the development phase, as well as can validate the level of the reliability and environmental adaptability of the equipment during finalizing the design and the manufacture phase.The effectiveness of Environmental Stress Testing (especially Accelerated Stress Testing) mainly depends on the capability of environmental simulation facilities. None but is the test spectrum abundant and controllable, it is possible to simulate the stresses environment needed for exposing weakness of the product. Based on summarizing the present status of the vibration test and vibration environment simulation technology in the world, the topic of simulation of super-gaussian random vibration environment with controllable frequency spectrum and its applications in Reliability Enhancement Testing is put forward. The main content and conclusions of the dissertation are as following:1. The fatigue failure enhancement mechanism of the characteristics (e.g. bandwidth, kurtosis and skewness) of the excitation and the dynamical characteristics(e.g. natural frequencies and damping ratio) of the specimen itself is studied. Then the characteristics of exciting signals should have for Vibration Enhancement Test are summarized, namely super-gaussian and controllable frequency spectrum. Thus the main research topic of this thesis is established.2. After analyzing the traditional methods of generating exciting signals in vibration control system of Electrodynamic(Electrohydraulic) Shaker, a new method of adjusting the skewness and kurtosis of exciting signals by second phase modulation is proposed. Based on this method, a new algorithm for generating super-gaussian and quasi-random vibration exciting signals with specified PSD, skewness and kurtosis is proposed. Simulation and experimental results validate the algorithm.3. The effects of time domain randomization on the kurtosis and skewness of...