Date of Award

2019

Document Type

Open Access Master's Thesis

Degree Name

Master of Science in Mechanical Engineering (MS)

Administrative Home Department

Department of Mechanical Engineering-Engineering Mechanics

Advisor 1

Gregory M. Odegard

Committee Member 1

Stephen M. Morse

Committee Member 2

Ibrahim Miskioglu

Abstract

This study is an extension to the design of ceramic materials component exposed to bullet impact. Owing to the brittle nature of ceramics upon bullet impact, shattered pieces behave as pellets flying with different velocities and directions, damaging surrounding components. Testing to study the behavior of ceramics under ballistic impact can be cumbersome and expensive. Modeling the set-up through Finite Element Analysis (FEA) makes it economical and easy to optimize. However, appropriately incorporating the material in modeling makes laboratory testing essential. Previous efforts have concentrated on simulating crack pattern developed during 0.22 caliber pellet impact on Borosilicate glass. A major concentration of work is on study of mesh pattern and size. The maximum principal strain has been considered to define the failure criteria which doesn’t correspond to theoretical properties. To appropriately incorporate material properties, the behavior of ceramics under ballistic impact could be tested through controlled impact Split Hopkinson Pressure bar (SHPB) testing setup. This paper discusses the results of SHPB bar testing on 1018 cold rolled steel to validate the experimental procedures and result analysis. The work has been extended to conduct testing on borosilicate samples under different input conditions. Strategies for improving the test result are proposed in the paper. The paper extensively covers the dynamics of glass material under ballistic impacts, various test procedures to obtain material model constants. Incorporating the material model in the previous FEA simulation makes it susceptible to numerous factors affecting the result. FEA characterization of SHPB test makes it suitable for modeling and correlating with the testing result of borosilicate glass. The FEA set-up is simplified to incorporate all the parameters affecting the test. Comprehensive analysis of the loading pulse is conducted to validate the model. This paper discusses specimen analysis through the standard material model in LS-Dyna MAT_110 for five different classes of ceramics. Inconsistencies between testing result and simulation have been identified and presented in this paper. The gaps in the study have been highlighted and means to obtain a good correlation is proposed in this paper to guide future work.

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