Experimental and Numerical Vibration Analysis of The Gun Control Unit Column with Isolator

Abstract

A remote-controlled weapon system can be integrated into the naval and ground platforms. The weapon system and its sub-units are exposed to the vibration that comes from the platform on which the weapon system is fitted. The weapon system and its sub-units are expected to withstand vibration-related failure throughout its life. Therefore, the fatigue analysis is carried out for the weapon system during the design process. The system is used in the tracked military vehicle. Hence, the tracked vehicle vibration test procedure is applied to the control column by using the shaker. The random vibration test procedure is presented in the document of the AECTP 400 Mechanical Environment Test. As a result of the test, the control column was broken from part of the base. This thesis is aimed to obtain a control column that will preserve its structural integrity after vibration test and to develop a finite element model of the weapon control unit validated with experimental modal analysis results. In the first part of the thesis, initially, the original structure is modeled by the finite element method, and the fatigue analysis is performed under the tracked vehicle random vibration test profile. Then the analysis is performed with a vibration isolator, which is assembled under the damaged part of the control column. The result of the analysis shows that the isolator prevents the damage occurring in the control column. Afterward, a prototype of the control column with the isolator is manufactured, and the accelerated track vehicle random vibration is applied to the prototype by using the shaker. The shaker test’s result proves that the isolator prevents the damage. In addition, the sine sweep vibration test is applied to the gun control unit, and one of the resonance frequency of the control column is determined. The obtained resonance frequency is different from the one which is calculated by finite element analysis, from which it can be deduced that the finite element model of the gun control unit is inaccurate. For this reason, the finite element analysis is needed to be validated. In the second part of the thesis, an accurate finite element model of the gun control unit is developed. At first, experimental modal analysis is performed. The impact hammer method, which is one of the experimental modal analysis techniques, is used. As a result, natural frequencies, corresponding mode shapes, and damping ratios are determined. The experimental modal analysis result is used to create a reference model. In addition, the elasticity modulus of the neoprene is determined with the help of the tensile test. Then the finite element model is updated according to the test results, and the finite element model is validated.