Identification of The Low Frequency Dynamic Behavior of Surrogate Explosive Materials

Jelena Paripovic, Purdue University

Abstract

The mechanical response of energetic materials, especially those used in improvised explosive devices and munitions, is of great interest in the defense community. The safe deployment of munitions in environments exposed to high levels of vibration requires an understanding of materials behavior under these conditions. The goal of this work is to characterize the mechanical material behavior of the energetic materials by developing robust models of low frequency uniaxial behavior. This is achieved by conducting low frequency harmonic and random base excitation tests on a mass-material system at various levels of excitation. Then, a two-stage system identification methodology developed in this research is used to determine system model structure and to estimate system parameters from which energetic material parameters (stiffness, damping and viscoelastic properties) can be extracted. Eight different model structures were chosen with varying stiffness, damping and viscoelastic terms to describe the mass-material system dynamic response. The stiffness and damping terms are estimated by using a continuous time system identification approach and a Prony analysis estimation technique is used to estimate the viscoelastic terms. The inclusion of a hysteretic damping term alongside a viscoelastic term improved the prediction of the response in the region of the mass-material system resonance. The Young's Modulus was estimated from linear approximations to the stiffness terms for the pure binder sample and the crystal solid-loaded sample. The system identification approach that has been developed can also be applied to identify models for other viscoelastic materials, such as foams and rubber-like materials.

Degree

Ph.D.

Advisors

Davies, Purdue University.

Subject Area

Mechanical engineering|Materials science|Applied physics

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