Insights into Shock-Driven Pore Collapse in PMMA Materials
Recent research conducted by Barry P. Lawlor, Vatsa Gandhi, and Guruswami Ravichandran has provided new insights into the behavior of porous materials under shock loading. The paper, titled "Full-Field Quantitative Visualization of Shock-Driven Pore Collapse and Failure Modes in PMMA," explores how the collapse of pores in polymethyl methacrylate (PMMA) relates to material failure and the generation of hot spots, which are critical for the performance of various materials used in energetic and structural applications.
The study employs a novel internal digital image correlation technique alongside plate impact experiments to measure the deformation surrounding a collapsing pore. This approach allows for the first-time full-field quantitative deformation measurements in the material around the pore. The researchers found that as shock stress increases from 0.4 to 1.0 GPa, two distinct failure modes emerge:
- Shear Localization: The first in-situ evidence of shear localization via adiabatic shear banding was observed.
- Dynamic Fracture Initiation: Dynamic fracture initiation occurs at the pore surface.
Additionally, numerical simulations using thermo-viscoplastic dynamic finite element analysis provided further understanding of the conditions leading to the formation of adiabatic shear bands and the stresses involved in the transition between failure modes.
These findings have significant implications for the design and analysis of materials that are subjected to high-stress conditions, such as those found in aerospace and military applications. Understanding the mechanisms of pore collapse and material failure can lead to the development of more resilient materials and improved safety protocols in their use.
The complete study can be referenced as follows: Lawlor, B. P., Gandhi, V., & Ravichandran, G. (2024). Full-Field Quantitative Visualization of Shock-Driven Pore Collapse and Failure Modes in PMMA. arXiv:2408.16931.