Abstract
Mechanical shock events experienced by electronic systems can be reproduced in the laboratory using Hopkinson bar tests. In such tests, a projectile strikes a rod, creating a pulse which then travels into the electronic system. The quality of these tests depends on the closeness of the shape of the incident pulse to a desired shape specified for each test. This paper introduces a new approach for controlling the shape of the incident pulse through the use of phononic material concepts, thereby improving the test procedure. Two dispersion-modifying concepts, phononic crystals and local resonators, are examined for their wave-shaping capabilities in one-dimensional elastic waveguides. They are evaluated using a transfer matrix method to determine the output pulse shape in the time domain. Parametric studies show that no single parameter allows for precise-enough control to achieve the possible desired output pulse shapes. Instead, the parameters of an approximate, discrete model for a combined phononic crystal/locally resonant system are optimized together to achieve the desired pulse shape. A sensitivity analysis documents that the pulse shape is relatively insensitive to errors in the optimized parameter values. The optimized discrete model is then translated into a physical design, which when analyzed using the finite element (FE) method shows that desired pulse shapes are indeed produced.
