Venkat ¹, P. V. Siva Rao ¹, Arun Kumar Singh ¹, Srikrishna ¹, Ranganath ²

Affiliations
1 MTRDC, DRDO, Bangalore - 560013, Karnataka, IN
2 University Visvesvaraya College of Engineering (UVCE), Bangalore - 560001, Karnataka, IN

Abstract

Objectives: The Young’s Modulus (E) plays key role in the vibration response of any structure. Hence its estimate with reasonable accuracy is of paramount importance. The Printed Circuit Board (PCB) used in military application consists of more than 6 layers, with pre-peg and copper composition. Methods/Statistical Analysis: The multiple layers PCB E value will vary from one design to other as it depends on the composition of layers. These PCB plates are subjected to vibration loads – sine, random and shock. A detailed work has been carried out to quantify the mechanical property of Young’s Modulus (E) of the PCB plate both analytically and experimentally. Findings: This E value obtained was used in the FEM analysis (using ANSYS 16) to solve the vibration response of the PCB. The study also includes analytical calculation and experimental estimation of natural frequency of the PCB plate for different boundary conditions. The natural frequency estimation through analytical and experimental methods show good correlation thus validating the estimation procedure of E of the PCB as well. Application: This work gives us a robust method for estimating Young’s modulus of Multi-layer PCB which find application in variety of military electronics.

Keywords

ANSYS, Natural Frequency, PCB Vibration, Random Vibration, Young’s Modulus.

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Venkat ¹, Varun ¹, Arun Kumar Singh ¹, Srikrishna ¹, Sharan Mudda ², Ravinder Jhorar ²

Affiliations
1 MTRDC, DRDO, Bangalore, IN
2 Manipal University Jaipur, Jaipur Campus, IN

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.

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