"Effects of Loading Rate and Surface Quality on Glass Failure"

Wayne Chen, School of Aeronautics and Astronautics, Purdue University

Mechanical failure of glass is dominated by surface flaws. It takes time for a surface-initiated flaw to propagate through the bulk. Thus, the failure is also rate-dependent. This study evaluates the loading-rate and surface-condition dependence of the flexural strength of a borosilicate glass using both a four-point-bending and a ring-on-ring setup. Quasi-static experiments are performed with a servohydraulic machine, whereas the dynamic experiments are conducted with a modified Kolsky bar. The tensile surfaces of glass bending specimens are subjected to 3 different surface treatments. Loading rates range from 0.7 MPa/s to 4×106 MPa/s. The results show that the flexural strength of the borosilicate glass increases with increasing loading rate. When the surface is chemically etched, the flexural strength increases by an order of magnitude.

Professor Wayne Chen received his Ph.D. in Aeronautics at Caltech in 1995. He is currently a Professor of Aeronautics/Astronautics and Materials Engineering at Purdue University. He has extensive experience in dynamic experimental technique development and dynamic material characterization. His precision dynamic experimental methods have been transferred to numerous laboratories including Sandia National Laboratories, National Institute of Standard and Technology, and U.S. Army Research Laboratory. He is a University Faculty Scholar at Purdue, a Fellow of American Society of Mechanical Engineers, and an Associate Fellow of American Institute of Aeronautics and Astronautics. He served as the Chairman of ASME’s Dynamic Response of Materials Technical Committee and is a member of the United States National Committee of Theoretical and Applied Mechanics.

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