Opportunity at U.S. Army Research Laboratory (ARL)
Effect of Loading Rate on the Deformation/Failure Behavior of Materials at Different Length-Scales
Weapons and Materials Research Directorate, Material Behavior
||Aberdeen Proving Ground, MD 210055066
Research focuses on understanding the effect of micro and substructures on the deformation and failure response of different length-scale materials at strain-rates of loading, including high strain rates. Materials that are being studied include metallic alloys, ceramics, soft and hard polymeric/biological (including cells) materials, propellants, thin films, fibers, and fiber-based-composites. The effect of stress state on the failure behavior and failure mechanisms at different rates of loading is also being investigated. In some classes of materials, we are especially interested in the relationship between structure and the failure that results from tensile and shear instability at high rates. Loading tools that are being used for high-rate investigations include compression, tension, torsion Hopkinson bars, and other specially designed loading systems. Experimental facilities also include Hopkinson bars that are designed for understanding the response of low-impedance materials and micro-scale materials. High speed visualization (up to ~10 million frames per second) combined with digital image correlation (DIC) techniques at macro to micro scales are used to understand and quantify the deformation and failure process during experiments. In addition to mechanical response, we are in the process of establishing methods to measure chemical and electrical responses of materials such as biological-cells at different loading rates. Optical (reflected, transmitted, fluorescence, confocal) and electron microscopes are used for pre-, in-situ and post-mortem quantification of the response of the samples with a known stress-strain history to relate the deformation and failure processes/mechanisms to stress-state history and micro/substructural features.
High rate; Failure; Deformation; Hopkinson bar; Microstructure; Substructure; Failure mechanisms; Soft materials; High rate experimental mechanics; Experimental mechanics at different length-scales; Biomaterials;
Open to U.S. citizens
Open to Postdoctoral applicants