MSE Seminar: The Role of Microstructure in Damage and Failure at High Strain Rates in BCC materials

Date/Time

04/24/2018
3:45 pm-5:00 pm
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Location

Rhines Hall Room 125
Rhines Hall
Gainesville, FL 32611

Details

Join the Department of Materials Science and Engineering for light refreshments and a discussion lead by Dr. Saryu Fensin of Los Alamos National Laboratory.

Understanding and predicting the response of materials under dynamic loading is a challenging problem due to complexities involved with the loading state and its interaction with various features in the microstructure. One phenomena that is closely associated with shock loading is spall fracture. This form of tensile damage begins with a material being shocked into compression followed by subsequent reflection of these shock waves into the sample as a rarefaction fan. These rarefaction waves act to accelerate material in the direction opposite to their propagation. However, when rarefaction fans interact, a region of intense tension forms, typically at high strain-rates. Depending on the magnitude of the tensile stresses, damage accrues in the tensile region through a series of void nucleation, growth, and coalescence eventually leading to full separation, producing a spall scab.
The goal of this work is to understand the interaction of the microstructure and how it couples with the peak stress and strain-rate generated during dynamic loading to dictate damage and failure in materials. As part of this work, I will present a series of experiments on high purity, well characterized tantalum samples subjected to shock-loading via gas-gun plate impact. Through careful selection of the flyer-plate velocity and material the peak compressive stress and the tensile strain rate were varied during the experiments. Metallography results from these samples with be discussed in the context of the preferred location of damage. These experiments will be coupled with molecular dynamics simulations to obtain further insights into the micro-mechanisms that drive damage and failure in BCC materials.

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