Guidelines for the Use of Approximations in Shock Response Analysis of Electronic Assemblies

In order to reduce the time and effort to create models and prevent excessive computer run times, approximations and simplifications are often used in the finite element analysis of the shock response of electronic assemblies. Typical approximations which might be used include neglecting components which have small masses and considering highly stiff connections as rigid connections. It is difficult to determine under what conditions approximations may be applied and to what extent they affect a model’s accuracy. Rather than depending only on an analyst’s experience or intuition, guidelines are desirable to prevent the inappropriate use of approximations. To illustrate the methodology for developing guidelines, this paper examines approximations involving a simple structure which is representative of structures found in electronic assemblies. This structure consists of a rigid body attached by a flexible connection to a beam. Approximations considered were: approximating the stiffness of the connection, neglecting the mass of the rigid body, and approximating the boundary conditions of the beam as either simply-supported or clamped. In developing guidelines a large number of individual analyses were necessary. An important aspect of this investigation is our proposal for a concise format for presenting the results of many analyses. The techniques which were used to reduce the amount of data to be presented are discussed.