Indian Journal of Science and Technology

Abstract

Objectives: Any device required to operate under vibration environment has to be tested for the same. The mounting pattern of vibration shaker is fixed. Hence a fixture as adaptor is needed for mounting the Device Under Test (DUT). Method/Analysis: These fixtures are to be stiff (natural frequency > highest frequency of test spectrum) to avoid fixture resonance leading to amplification of loads. In the present study, two fixtures – 1) with single mount 3 orientation capability and 2) capable of for 3 axes simultaneous loading were designed, analysed (using ANSYS16) and developed with the aim of reducing time in a single test and effort during testing. Findings: The fixtures were tested by regular vibration shaker as well as a hand held analyser. The analysis and testing yielded good correlation for the natural frequency estimate (< 15% deviation).Using fixture-1, 4 units with 3 orientations can be tested simultaneously and each of the devices can be tested for the remaining orientations during the subsequent tests. With fixture-2 one can test the device for all 3 axes loading in a single test thus reducing the testing time when accounted across a number of devices. Applications: As most of the time and effort during vibration testing goes in change of orientation and arrangement of slip-table (assembly and dis-assembly of the fixture-DUT) the fixtures designed can go a long way in minimising the time and manual labour when accounted across many units.
Keywords: Frequency Response Function (FRF), GRMS, Modal Testing, Random Vibration, Vibration Fixture