The author introduces a test platform system that has been developed for variable-speed control moment gyroscopes(VCMGs). VCMGs are important actuators for spacecraft attitude control. The test platform consists of two VCMGs driven by servo motors and sensor modules. The control program has been coded by the NI LabVIEW. Accelerometers and gyros have been used to measure the attitude angle and angular speed of the platform. The 2nd order low pass filters have effectively filtered out noises from measurements. Wheel speeds and gimbal angles have been controlled satisfactory by PI control. Through some tests, moment generation has been verified. The moment has been generated as commanded. However, friction effect by a ball bearing, that supports the platform’s rotation, has been not negligible. As further studies, friction reduction will be studied. In conclusion, this test platform will be used for engineering education and research.

In this study, dynamic characteristics and seismic capacity of the nuclear power plant piping system are evaluated by model test results using multi-platform shake table. The model is 21.2 m long and consists of straight pipes, elbows, and reducers. The stainless steel pipe diameters are 60.3 mm (2 in.) and 88.9 mm (3 in.) and the system was assembled in accordance with ASME code criteria. The dynamic characteristics such as natural frequency, damping and acceleration responses of the piping system were estimated using the measured acceleration, displacement and strain data. The natural frequencies of the specimen were not changed significantly before and after the testing and the failure and leakage of the piping system was not observed until the final excitation. The damping ratio was estimated in the range of 3.13 ~ 4.98 % and it is found that the allowable stress(345 MPa) according to ASME criteria is 2.5 times larger than the measured maximum stress(138 MPa) of the piping system even under the maximum excitation level of this test.

There has been much research on the reliability and durability of the product life cycle using accelerated life test(ALT), accelerated stress test(AST) and accelerated stress audit(ASA) in the industry. Most of these systems use vibration induced by acceleration and deceleration. The device used for these kinds of research should have wide-band exciting frequency ranges to find the weak mode of the product. In this paper, platform of ALT based on the Stewart platform is controlled by using pneumatic actuators. Pneumatic actuators use motion and impact in this paper to cause wide-band exciting frequency. The change in frequency and pressure in the six cylinders is used to control the level of exciting vibration. Many control strategies are tested to improve the performance and one of the best control algorithms is suggested.

Recently, there are many researches that are performed for increasing reliability about product life cycle using ALT(Accelerated Life Test), AST(Accelerated Stress Test) and ASA(Accelerated Stress Audit) in the industry. The test of this research needs a device that has wide-band frequency vibration. But most test devices such as HALT only show the good response of high frequency area. In this research, the platform of ALT was developed based on Stewart Platform using pneumatic Actuators. Pneumatic Actuators represent response of wide-band frequency by motion and mpact. Cylinders of Stewart Platform is operated based on frequency and pressure. This research shows system characteristic of Platform to develop the control algorithm of accelerated life test platform in future research.