Numerical Simulations of the Mechanical Behavior of Adobe
Numerical simulation of geomaterials in the literature is sparse, and little data is available on modeling and simulation of high-velocity penetration of geomaterials using constitutive models built into hydrocodes. The brittle fracture kinetics (BFK) con
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Numerical Simulations of the Mechanical Behavior of Adobe Christopher S. Meyer
Abstract Numerical simulation of geomaterials in the literature is sparse, and little data is available on modeling and simulation of high-velocity penetration of geomaterials using constitutive models built into hydrocodes. The brittle fracture kinetics (BFK) concrete material model in continuum mechanics codes has been used to simulate adobe targets; however the material parameters utilized for adobe were those of concrete with the unconfined compressive strength adjusted to match the adobe, which does not capture the pressure-dependent strength behavior of adobe. In this work, material parameters for adobe are derived from available mechanical test data. The resulting parameters are for use in the Holmquist-Johnson-Cook (HJC) constitutive model for concrete, and this work includes an exploration of the material’s pressure dependent strength behavior. The HJC model captures the pressure and strain-rate-dependent strength behavior of geomaterials reasonably well, is readily available in many continuum mechanics codes, and is commonly used to simulate high-velocity penetration. This work also presents numerical simulations of high-velocity penetration of adobe targets and compares the results to available experimental penetration data. Keywords Numerical simulations • Adobe brick • Penetration
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Introduction
The U.S. Army’s interest in urban operations has led to efforts at the U.S. Army Research Laboratory to develop an initial set of material model parameters to enable physics-based penetration simulations of high-fidelity adobe brick wall models. These material model parameters take advantage of the Holmquist-Johnson-Cook (HJC) model for concrete [1]. A search of the open literature turned up very little involving experiments or modeling and simulation of weapon effects against adobe targets. While dynamic material properties for concrete are well characterized, the dynamic material properties of adobe are in the early stages of investigation. Research involving penetration and perforation experiments of adobe bricks has only recently begun to be published, for example Heine, et al. [2]. To the author’s knowledge, research involving numerical simulation of penetration and perforation of adobe remains unavailable in the open literature. In early numerical simulations, adobe has been simulated using the Brittle Failure Kinetics model [3] with concrete material properties adjusted by the input of the adobe material’s unconfined compressive strength (Volkmann and Moser (2011) Alliant techsystems, private communication); while an acceptable option for initial investigations, this approach does not capture the behavior of adobe in penetration and perforation simulations with an adequate degree of fidelity. The subject work seeks to develop a means of numerically simulating adobe penetration and perforation: this aim requires a constitutive material model that captures the geomaterial family of behavior, material parameters for adobe
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