Abstract

In this paper, we introduce a computational model for the simulation of hypervelocity impact (HVI) phenomena which is based on the Discrete Element Method (DEM). Our paper constitutes the first application of DEM to the modeling and simulating of impact events for velocities beyond 5 . We present here the results of a systematic numerical study on HVI of solids. For modeling the solids, we use discrete spherical particles that interact with each other via potentials. In our numerical investigations we are particularly interested in the dynamics of material fragmentation upon impact. We model a typical HVI experiment configuration where a sphere strikes a thin plate and investigate the properties of the resulting debris cloud. We provide a quantitative computational analysis of the resulting debris cloud caused by impact and a comprehensive parameter study by varying key parameters of our model. We compare our findings from the simulations with recent HVI experiments performed at our institute. Our findings are that the DEM method leads to very stable, energy–conserving simulations of HVI scenarios that map the experimental setup where a sphere strikes a thin plate at hypervelocity speed. Our chosen interaction model works particularly well in the velocity range where the local stresses caused by impact shock waves markedly exceed the ultimate material strength.

Highlights

  • Since the beginning of the space age in the 20th century, the number of man–made debris particles in the Earth’s orbit has constantly risen

  • In order to asses the risk of future collision events, it is important to be able to predict the impact dynamics of the resulting debris cloud when space debris traveling at high velocity strikes a satellite structure

  • A discrete approach approximates a material as a collection of Newtonian particles [28,29]. One such method is the Discrete Element Method (DEM) which originates from Cundall and Strack [30] and has found many new applications in different fields spanning chemical engineering, pharmaceuticals, powder metallurgy, agriculture and many others

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Summary

Introduction

Since the beginning of the space age in the 20th century, the number of man–made debris particles in the Earth’s orbit has constantly risen. Still others use a hybrid approach where the compressive pressures are computed at the particles and the tensile pressures at the elements [26] Such codes produce accurate results [27], but contain the combined complexity of both methods. A discrete approach approximates a material as a collection of Newtonian particles [28,29] One such method is the Discrete Element Method (DEM) which originates from Cundall and Strack [30] and has found many new applications in different fields spanning chemical engineering, pharmaceuticals, powder metallurgy, agriculture and many others. Various DEM approaches have been used to simulate the behavior of cohesive granular matter under different impact situations with velocities below 100 ms−1 These approaches used differing models and were applied to specific problem areas with varying degree of success [31,32]. We evaluate our model within a wide range of impact conditions to determine its suitability for numerical computation of HVI phenomena

Simulation Model
Initial Setup
Particle Potentials
Contact Potentials
Bonded Potentials
Sizing and Convergence Properties of Our Particle Model
Geometric Sizing Properties
Convergence Properties
Results and Discussion
Choice of Model Parameters
Validation with Experiment
Extension of Debris Cloud
Shape and Degree of Fragmentation
Analyzing Fragmentation
Conclusions
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