CAREER: Innovations in Microscale Plasticity and Failure Mechanics to Enable Microforming Processes, with Bending and Hydroforming as Paradigms

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This Faculty Early Career Development (CAREER) grant aims at enhancing the understanding of deformation and failure of microtubes (diameter 1mm) with few (10) grains through the thickness. Such components abound in microelectronic, microfluidic and biomedical applications. Their mechanical behavior is dominated by the limited number of through-thickness grains, which renders the continuum approximation unsuitable. In this research, stainless steel 304 and CuZn 30 brass microtubes will be inflated under internal pressure and axial load and taken to failure, using a testing machine to be created for this purpose. These experimental findings will then help establish a microstructurally-informed, crystal plasticity constitutive model, with the aid of the research partner in South Korea. Finite element simulations of the experiments will be coupled with this material model to capture the deformation and failures observed. Subsequently, two micromanufacturing processes (microtube bending and hydroforming) will be examined using a combination of experiments and analysis. A microtube bending device will be created for the purposes of this project, while an existing apparatus in Cologne, Germany, will be used for the microtube hydroforming experiments. The performance of the numerical and constitutive models established above will be examined in light of these experiments and will be improved as needed, to capture the failures observed. If successful, this research will contribute to the scientific understanding of grain-dominated deformation and failure of materials. It will enable the broader implementation of microtube bending and hydroforming in innovative microelectronic, microfluidic and biomedical products, benefiting the American industry. The award will also provide two graduate students with the opportunity to perform research for a total of 18-24 months in Germany and South Korea, preparing them well for the globalization of research and industry. Lastly, training and integrating minorities will result in a more diverse, fair and internationally competitive workforce.