GOALI: Multi-Scale Characterization and Modeling of Anisotropy and Failure of Aluminum Alloys for Automotive Applications

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Increasing the fuel efficiency of automobiles is a major driver for the automotive industry's recent efforts towards lightweight manufacturing. To achieve this goal, industry has identified the use of aluminum alloys in vehicle design and manufacture as an essential technology. Aluminum, with a density of 34 percent that of steel, is plentiful and recyclable, but has one-third the stiffness of steel, is more expensive to produce, has more complex material behavior, is less ductile with limited design experience within the automobile industry. To understand these properties and overcome these challenges, robust computational models of deformation and failure are essential. This Grant Opportunities for Academic Liaison with Industry (GOALI) award is a cooperative project between Industry (General Motors) and University (University of Texas at Austin) which supports fundamental scientific research aimed at developing enabling simulation technology for aluminum alloys through experimentation, modeling and validation. This will be achieved through a strong interaction between the university and industry research teams, including graduate student training through summer residency in General Motors labs and exposure of undergraduate students, including those from underrepresented groups, to current industry challenges. These interactions will provide broad impact by ensuring that the research generates new scientific knowledge with long-term benefits to engineering problems aligned with industrial needs, and will train future leaders in academia and industry with the skills to lead scientific innovation with engineering applications.The experimental approach of the research plan includes conducting custom designed biaxial tests on tubes using two aluminum alloys to establish the evolution of plastic deformation up to failure under a range of triaxialities and Lode angles, while monitoring the deformation with three-dimensional digital image correlation. In-situ experiments on small-scale specimens under electron microscopes will be conducted, where the evolution of deformation under different stress states can be quantified up to failure. Small-scale testing will be performed using electron backscatter diffraction imaging in order to establish the evolution of texture. The modeling efforts include calibration of state of the art anisotropic yield functions and development of dependable failure criteria, and enhancement of the failure criteria using results from the small-scale experiments and establishment of the evolution of yield surfaces through crystal plasticity. The integrated approach involving well-calibrated continuum level plasticity and failure models, validated through their performance in simulating independent axial quasi-static and dynamic tube crushing experiments, is the major intellectual merit of the work. Transfer of the developed technology to industry can be immediate, as the crushing simulations developed and enhanced through this research are one of the most demanding tasks in automobile safety assurance.