细长偏心舱体振动试验夹具设计分析与验证
Design and Validation of Fixture for Slender Off-centre Pod in Vibration Test

振动试验是考核航空航天产品可靠性与环境适应性的重要手段。针对某大型细长偏心舱体的振动试验，介绍了振动试验的二自由度系统理论模型，然后采用配重法设计了其振动试验夹具，并通过有限元软件ABAQUS分析了夹具在自由状态和连接试验件状态的模态参数和随机振动响应。结果表明，该夹具自由状态的1阶固有频率为198.6 Hz，连接试验件状态的1阶固有频率为202.1 Hz，最大放大因子为1.6，连接点加速度的最大偏差为31.4%，上述指标均符合振动试验夹具设计要求。最后用该夹具对细长偏心舱体进行了随机振动试验，试验控制平稳，偏差在容差范围内，验证了夹具设计的合理性。
Vibration test is an important way to examine reliability of aerospace products. For a large slender off-centre pod vibration test, the theory modal of two freedom vibration system is firstly introduced. Then, the vibration test fixture is designed with balance weight method. The modal parameters and random dynamic response of the fixture are analyzed using finite element software ABAQUS in both free state and test specimen joint state. The results indicate that first natural frequency of the fixture in free state is 198.6 Hz. First natural frequency of test specimen joint state is 202.1 Hz. The amplification factor of the fixture is 1.6. The largest acceleration error from different joint points is 31.4%. Above-mentioned technique data meets the standards of vibration test fixture design. Finally, the vibration test for slender off-centre pod is carried out using the fixture, from which controlling is steady and errors are within the tolerance range. The rationality of the fixture is verified