Resolving the Dynamic Behavior of Earth Materials Using a Pressure Shear Configurations
Abstract
The objective of this project is to develop new areas of research to build a better understanding of the dynamic response of heterogeneous brittle earth material systems, where brittle materials include sand, rock and concrete. This will be accomplished by pursuing three different but symbiotic approaches: 1) explore novel pressure-shear experimental techniques to probe the material s dynamic response under various loading conditions, 2) initiate multi-scale computer based simulations that capture the mesoscale, 3) build statistically based models and evolution equations to represent heterogeneous systems, effectively bridging the gap between the meso- and bulk scale. The work described herein will be executed in the first three years at Marquette. Once development is complete the possibility of conducting companion experiments at the Dynamic Compression Sector (DCS) will be explored in years 4 and 5. Finally, this program will train graduate students with skills necessary to address the challenging problems of interest to the DoD and DoE community. The objective of this research is to: o generate laboratory loading conditions of materials of interest that are more representative of actual loading conditions that exist in nature, specifically focusing on impact and blast events, o explore the use of mesoscale computational techniques to gain a better understanding of heterogeneous earth material behavior associated with the penetration of earth materials, o develop new analytic, statistically based, methods to describe heterogeneous material behavior, o introduce and educate the next generation of STEM workers with a skill set applicable to conduct basic research in and solve complex problems for defense-related areas, o build the knowledge base of earth based material behavior so that designers can predict and control penetration performance to ultimately meet operational requirements. 1) Pressure-Shear Experiments: Improving the Standard Planar-impact test presented in Fig. 1a are the standard benchmark high strain-rate testing technique. Although highly resolved they lack further building our understanding of stress states that contain shear. The work proposed here is focused on building our understanding of earth-based materials subjected to off diagonal pressure and shear loading states. Figure 1b illustrates the plane pressure-shear experiment proposed here which provides a unique opportunity to better explore mesoscale phenomena such as shear and friction, mechanisms of damage and variations in material heterogeneity such as porosity, texture and granularity. The results of which can be used to better understand the loading states generated during penetration events. 2) High Fidelity Mesoscale Simulations: In order to design systems to survive extreme environments such as impact and penetration or in order to better understand how to facilitate such events, we need a better understanding of how these heterogeneous systems adsorb and store energy, mechanisms that induce damage at the micro-scale. This proposal addresses these issues by proposing highly resolved computer simulation. Figure 2 presents representative simulations at a resolution which is sufficient to resolve very fine scale structure within the heterogeneous material; thereby accurately capturing such irreversible phenomena such as pore collapse, dynamic yield and phase change. 3) Statistically based Evolution: Developing the Next Generation of Engineering Models The work proposed here will incorporate both the simulations and experiments described above in order to advance our understanding of how earth based heterogeneous systems respond to dynamic loading. From the simulations and experiments we will be able to generate the next generation of fast models to incorporate in engineering systems or larger systems level simulations.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- May 26, 2016
- Source ID
- HDTRA11510073
Entities
People
- John Borg
Organizations
- Defense Threat Reduction Agency
- Marquette University