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Research Papers

Shock and Dynamic Loading in Portable Electronic Assemblies: Experimental Results

[+] Author and Article Information
A. F. Askari Farahani, M. Al-Bassyiouni

Mechanical Engineering Department,  Center for Advanced Life Cycle Engineering (CALCE), University of Maryland, College Park, MD 20742

A. Dasgupta1

Mechanical Engineering Department,  Center for Advanced Life Cycle Engineering (CALCE), University of Maryland, College Park, MD 20742

1

Corresponding author.

J. Electron. Packag 133(4), 041010 (Dec 09, 2011) (10 pages) doi:10.1115/1.4005090 History: Received March 12, 2010; Revised April 13, 2011; Published December 09, 2011; Online December 09, 2011

The development of portable electronics poses design challenges when evolving new designs for high strain-rate life cycle loading, such as in drop events, blast events, vibration, ultrasonic process steps, etc. This paper discusses an experimental investigation of the transient response of a portable electronic product and its subassemblies to dynamic mechanical loading encountered in drop and shock conditions. The portable electronic product tested in this study consists of a circuit card assembly and a battery pack supported in a two-piece plastic housing with a separate battery compartment. Dynamic loading, consisting of various shock profiles, is applied using an electrodynamic shaker. A number of drop tests are also conducted on a drop tower. Fourier transform technique (FFT) is utilized to analyze the dynamic response of the printed wiring board and the plastic housing in the frequency domain. Tests at the subassembly level are used to study the dynamic response of the individual constituents. The nonlinear interactions due to dynamic contact between these subassemblies are then investigated through shock and drop testing at the system level. These results will be used in a subsequent study to investigate the ability of finite element models to accurately capture this transient response of complex portable electronic assemblies under shock and drop loading. The long-term goal of this combined study is to demonstrate a systematic modeling methodology to predict the drop response of future portable electronic products, so that relevant failure modes can be eliminated by design iterations early in the design cycle.

Copyright © 2011 by American Society of Mechanical Engineers
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References

Figures

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Figure 3

Typical drop tower

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Figure 4

Test setup for the clamped PWB

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Figure 5

Test setup for spring-loaded PWB

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Figure 26

Repeatability of PWB xx-strain response (measured at point 2 as shown in Fig. 2)

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Figure 27

Repeatability of PWB acceleration response

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Figure 28

FFT of strain gage response and FRF of the accelerometer, due to drop loading

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Figure 10

Acceleration magnification factors for the clamped PWB

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Figure 11

Flexural strain response ɛXX of the clamped PWB

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Figure 12

Response of clamped PWB to half-sine shock

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Figure 13

Amplitude density spectrum of half-sine pulse of duration π/w0

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Figure 14

FFT of the fixture motion in response to half-sine shock loading

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Figure 15

Fixture and PWB accelerations for drop test on clamped PWB

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Figure 16

Strain response at the post (point A) measured in the x-direction, during drop test of clamped PWB

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Figure 17

FFT response of the drop table fixture to half-sine drop loading

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Figure 18

FFT response of strain gage in Fig. 1 to half-sine drop loading of clamped PWB

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Figure 19

Frequency response function of the accelerometer on clamped PWB due to half-sine drop loading

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Figure 20

Frequency response function of spring-supported PWB under broadband excitation

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Figure 21

Frequency response function of the empty case at the two accelerometer locations in the figure

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Figure 22

Fixture acceleration and PWB acceleration response measured at locations shown in Fig. 7

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Figure 23

FFT of the fixture motion in response to the half-sine shock loading

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Figure 24

PWB acceleration versus fixture acceleration in product drop test

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Figure 25

PWB strain response at point 2 in full product drop test

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Figure 6

Test setup for empty housing

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Figure 7

Test setup for full product

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Figure 8

Frequency response function of the clamped PWB

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Figure 9

Shock response of clamped PWB

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