Abstract

A material in use, anywhere from a plastic bag to common infrastructure, will eventually fail from deformation. When strained, the material chemical structure can change, and that change is dependent on many factors, including the amount of strain and strain rate. Understanding the relationship between physical properties and structural changes due to deformation can allow structural manipulation to achieve the desired physical properties. Additionally, research into non-destructive testing (NDT) methods can be used as supporting evidence for replacing destructive testing methods and possible infield stress monitoring. In this dissertation, X-ray diffraction (XRD) and second-harmonic generation (SHG) are the main NDT techniques used to collect data for structural analysis during deformation. In the first project, we analyzed HDPE strained to different extensions and different strain rates using XRD to understand the changes in crystalline polymer structure during deformation. The findings highlighted qualitative and quantitative differences in preferred orientation, unit cell parameters, crystallite size, and crystalline makeup when varying strain and strain rate. In the second project, we compared SHG changes in strained steel with dislocation density changes from electron backscatter diffraction (EBSD), a well-established indicator of deformation. The results indicated SHG as a potential complementary method for analyzing changes from deformation as a way to overcome the limitations of EBSD. The conclusions from these projects present strong evidence towards the use of these NDT methods for analyzing structural changes caused by deformation.

Degree

PhD

College and Department

Computational, Mathematical, and Physical Sciences; Chemistry and Biochemistry

Rights

https://lib.byu.edu/about/copyright/

Date Submitted

2025-04-23

Document Type

Dissertation

Handle

http://hdl.lib.byu.edu/1877/etd13616

Keywords

structural analysis, non-destructive testing, tensile deformation, high-density polyethylene, X-ray diffraction, stainless steel, electron backscatter diffraction, second-harmonic generation

Language

english

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