Effect of excitation conditions on the durability of high standoff electronic components and assemblies under multiaxial vibration excitation

Abstract

Electronic assemblies often experience multiaxial vibration environments in use and tall, heavy components are more vulnerable under such loading than are short, light components. The added vulnerability comes from higher response due to nonlinear dynamic amplification of the response under simultaneous multiaxial excitation, termed multi degree of freedom (MDoF) excitation. This paper investigates the geometric nonlinearities and the resulting cross-axis interactions that tall and heavy electronic components experience when subjected to vibration excitation simultaneously along two orthogonal axes. Multiaxial vibration experiments were conducted on tip-loaded cantilever beams to explore the nonlinear vibration response of tall, heavy electronic components. Harmonic base-excitation was simultaneously applied in two orthogonal axes (with a different frequency in each axis), and the phase “difference” between these two harmonic signals was parametrically varied to see the effect on the response amplitude. Based on prior studies, the frequency of the transverse excitation was selected to be the fundamental natural frequency of the cantilever beam and that of the axial direction was selected to be twice as large to maximize the cross-axis interaction. Phase is seen to have a very significant effect on the nonlinear amplification of the response. Nonlinear finite element simulations were conducted to verify and explain the experimental observations.