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Casselberry, FL, United States

Chen Z.-W.,Zhejiang University | Wen X.,Zhejiang University | Zhou J.-C.,Econ Technologies | He H.-N.,Zhejiang University
Zhendong yu Chongji/Journal of Vibration and Shock

Traditional vibration tests based on acceleration response control are intended to control the acceleration of shaker platform according to specified acceleration specification. This kind of control may sometimes lead to over testing phenomenon at the natural frequency of testing article. Force limited vibration test is able to mitigate that tendency. Detailed calculations for force limitation specification were presented on the basis of the model of simple two-degree-of-freedom system (TDFS). Furthermore, the spectra of force and acceleration between spacecraft bracket and shaker platform were derived. Then the force limited random vibration test and force limited sine vibration test were carried out for spacecraft bracket. Experimental results indicate that the force limited vibration test in terms of force spectrum derived from the simple TDFS model can simulate the realistic dynamic environment better than the conventional acceleration response control vibration test, and the over testing tendency can be alleviated effectively. Thus those results offer a good verification for spacecraft vibration test. Source

Chen J.-Y.,Zhejiang University | Wang H.-D.,No800 Institute Of The Shanghai Aerospace Bureau | Zhou J.-C.,Econ Technologies | He H.-N.,Zhejiang University | Chen Z.-W.,Zhejiang University
Zhendong yu Chongji/Journal of Vibration and Shock

More and more people have paid attention to the multi-exciter vibration testing system since it can simulate the vibration environment more really, and now it has become a development tendency of environmental vibration test. The basic control principle of multi-exciters vibration testing system was presented and the key technologies, namely, the time-domain waveform replication, which includes iterative algorithm and overlap connection of driving signal, and the frequency spectrum replication, which includes feedback correcting logorithm and time randomization were introduced. A summary of control technologies for multi-exciters vibration testing was given with its prospect discussed. Source

Tian P.,Zhejiang University | Tian P.,Zhenjiang College | Chen Z.-W.,Zhejiang University | Jing W.,Econ Technologies
Zhendong yu Chongji/Journal of Vibration and Shock

To overcome the poor control precision of iterative learning control (ILC) which is generally used in earthquake simulation test, an adaptive control method was proposed. Adaptive control can obtain high simulation precision for seismic wave, by continuously identifying the transfer function of shaking table to overcome the time-variation of hydraulic system. On the basis of analyzing the disadvantage of pre-test step, the test method was so improved that the earthquake simulation test can be completed without conventional pre-test step, and the correlation coefficient between reference signal and control signal in time domain can reach a high level. Several typical earthquake wave experimental results, got on Zhejiang University shaking table, indicate that by the improved test method, the first frame correlation coefficient between reference signal and control signal in time domain can reach above 75% without pre-test step, while the experimental time is shortened; and after several frames of earthquake simulation test, the correlation coefficient can reach 95% through identifying the transfer function continuously. Source

Econ Technologies | Date: 2010-11-17

Vibration data acquisition and signal analysis systems comprised of network interfaces and input/output modules for industrial test and measurement.

Econ Technologies | Date: 2013-08-27

Computer application software for mobile phones, tablet computers, laptop computers and desktop computers, namely, software for the electronic storage, sharing and exchange of data files between devices.

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