Date of Award:
Master of Science (MS)
Mechanical and Aerospace Engineering
Ryan B. Berke
Ryan B. Berke
Ductility is the measure of how much a material can stretch before separation. It is usually measured in percent elongation, which is the amount a material stretches divided by its original length before stretching. This is an important property to understand for both the design for performance and safety. A material’s ductility can be influenced by several factors including heat treatment, machining, temperature, and radiation dose. Materials used in nuclear energy facilities are often exposed to all these factors, and it is important to be able to understand ductility at each possible combination.
Ductility is usually characterized through tension tests where a material is stretched until separation and the percent elongation is measured. However, ductility measured this way is dependent on the specimen geometry, meaning specimens of different lengths and thicknesses of the same material produce different percent elongation values. To account for this, ductility scaling laws have been developed that scale percent elongation to specimens of different sizes. Traditionally, these laws require testing multiple different specimen geometries to empirically extract the scaling parameters. This can be cost-prohibitive for many materials used for nuclear energy. This work develops a technique for extracting scaling parameters from a single specimen with the use of Digital Image Correlation—a camera-based measurement that extracts displacements from the pixel data across the entirety of the specimen. Improvements to the current scaling laws have been proposed, and the technique is validated by testing specimens of multiple different geometries.
Smith, Adam J., "Development of a Variable Extensometer Method for Measuring Ductility Scaling Parameters" (2021). All Graduate Theses and Dissertations. 8044.
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