Shock and Dynamic Loading in Portable Electronic Assemblies: Modeling and Simulation Results

In this study, the transient response of electronic assemblies to mechanical loading encountered in drop and shock conditions are investigated with transient finite element methods. Many manufacturers face design challenges when evolving new designs for high strain-rate life cycle loading. Examples of high strain-rate loading include drop events, blast events, vibration, ultrasonic process steps, etc. New design iterations invariably bring new unexpected failure modes under such loading and costly trial-and-error design fixes are often necessary after the product is built. Electronics designers have long sought to address these effects during the design phase, with the aid of computational models. However, such efforts have been difficult because of the nonlinearities inherent in complex assemblies and complex dynamic material properties. Our goal in this study is to investigate the ability of finite element models to accurately capture the transient response of a complex portable electronic product under shock and drop loading. Finite element models of the system are generated and calibrated with experimental results, first at the subsystem level to calibrate material properties and then at the product level to parametrically investigate the contact mechanics at the interfaces. The parametric study consists of sensitivity studies for different ways to model soft, nonconservative contact, as well as structural damping of the subassembly under assembly boundary conditions. The long-term goal of this 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.