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Date of Award
Campus Access Master's Report
Master of Science in Mechanical Engineering (MS)
Administrative Home Department
Department of Mechanical Engineering-Engineering Mechanics
Committee Member 1
Paul van Susante
Committee Member 2
A brittle cylindrical under high speed projectile impact can shatter into pieces and cause subsequent damage to neighboring components. To build any safety mechanism, either for cylindrical object or the surrounding, experimental trial of safety mechanisms is necessary. However, to make it economical, simulating the shattering phenomenon in FEA will be an even better idea.
This study is focused on simulating the crack pattern developed on a Pyrex 7740 borosilicate glass cylinder which is under impact by a 0.22 caliber lead pellet. The crack pattern develops right after the pellet hits cylinder and leaves it by piercing through the other side, before shattering it into pieces.
In the simulation, there are factors affecting the crack pattern which are mesh pattern, mesh size and maximum principal strain-based failure criteria. Mesh pattern governs the style in which the crack propagates whereas the mesh size decides how well defined and wide the cracks will be and the strain-based failure criteria determines the strain at which the individual elements fail in the simulation to form a crack, which is instrumental in obtaining a good response without making it too soft or too stiff. Element deletion method is used in this case to model dynamic fracture of the cylinder material.
The effects of these three factors have been explored in this study. A mesh convergence study has helped in determining the mesh size whereas comparison of results gives a better sense of mesh pattern. Manual iterations with different failure strain values give an idea on the ideal range of the failure strain with a tolerance less than 5e-6. The best combination of all has been determined with a step by step exploration of effects of variation in the values of the aforesaid 3 parameters, which yields a crack pattern in better agreement with the lab results. LS-Dyna solver has been used to simulate this study.
Gandhi, Sandesh Suresh, "Simulation of Crack Pattern on Borosilicate Glass Cylinder on Pellet Impact", Campus Access Master's Report, Michigan Technological University, 2017.