Study on the Configuration of Vibration Test for Slender Objects Operating in Unconstrained Conditions

Abstract

Vibration testing is necessary for functionality and durability evaluations of equipment that may undergo performance degradation and fatigue damage due to operational vibrations. Here, effective configuration techniques for vibration testing of equipment with high slenderness ratio operating in unconstrained conditions were studied. Excitation, support, and measurement locations are the most essential and important factors for the vibration test configuration. A finite element method was used to calculate the normal modes of the equipment, and suitability indexes as excitation and support location were obtained using eigenvectors of the dominant normal modes. The measurement locations of vibration response were obtained via the effective independence method using eigenvectors of the dominant normal modes. Indexes of the response of dominant modes to vibration excitation were generated for each candidate surface location of the missile through vibration testing involving various excitation, support, and measurement locations. The suitability indexes of excitation and support locations exhibited a high correlation with the indexes of vibration response magnitude in the dominant normal modes of the equipment. The vibration responses of the dominant normal modes were observed the largest in the measurement location set determined by the technique used in this study. Therefore, the vibration test configuration of equipment with high slenderness ratio can be designed and planned effectively to excite and observe the dominant normal modes of equipment significantly by the techniques and procedures proposed in this study.