Zhang, Sen2019-04-092019-04-092019-02https://hdl.handle.net/11299/202405University of Minnesota M.S.M.E. thesis. February 2019. Major: Mechanical Engineering. Advisor: Brain Hinderliter. 1 computer file (PDF); x, 63 pages.Shear tests are necessary to properly evaluate a material’s shear properties; however, common shear test methods have some limitations. The modified twist-plate shear method is an innovative shear test, which was developed to compensate the drawbacks of previous shear test method, because it has some distinctive advantages including efficiency, relatively low cost, reliability. In addition, it’s designed for flat square samples and applying force at different angles of the specimen. The thesis presents the prototype of the modified twist-plate shear method and analyzes its advantages based on the analysis on the common shear test methods, then conducts the experiments and simulation respectively to do further analysis and comparison. In this study, tested samples ranged from the isotropic and homogeneous material sample, which is a square shape steel panel, to a simple laminate sample, which is the sandwich structure made by steel panel and silicone. The material properties for the sandwich structure were determined by compression test before shear experiments with an elastic modulus of around 0.78MPa and 200GPa for the core and face sheets, respectively to be used in analytic and numeric simulations. Two kinds of samples with different thicknesses were tested by three-point bending and the modified twist-plate shear method. These methods have been evaluated according to three criteria: analytic solutions, experimental measurements and simulation results. Finite element helps inform whether stress-strain mechanisms and thus the applicability of the analytic solution. According to the comparison between the experimental data and simulation results, shear forces are difficult to separate from the combined forces in three-point bending even for the simple laminate specimen. Therefore, testing was done with the modified twist-plate shear method on the same type of samples. With different sample thicknesses simulated, the load was found to increase with increased sample angle. However, the relationship between load and displacement with angled specimens was not as clearly separable into shear and compression as hoped. Other factors may affect simulation results were also considered, harder core materials and face sheets, the position of load points, and different loading conditions. Taken all together, the results provided a specific condition which the sandwich structure with stiffer face sheets and two load points pushing together could isolate shear forces.enThesis or Dissertation