Mechanical Engineering ETDs

Publication Date

Spring 4-1-2020

Abstract

The importance of internal crack pressure on the extent of crack propagation is studied using both numerical and experimental results. Experimental data were obtained from shock tube testing of internally pressurized quasi-brittle hollow cylinders loaded to failure. Half of the samples were tested with an inserted membrane that transferred the shocked fluid load but prevented the fluid from entering the developing cracks. In the other cases, the membrane was removed allowing the fluid to enter the crack and assist development of fracture. A novel approach to modeling this complex structural response involving dynamic failure and fluid structure interaction is presented, based on a modified decohesive failure constitutive model and numerical technique. Initial results suggest this relatively simple approach is able to capture pressurized crack development. The algorithm was also used to model pre-formed notches inscribed on the inner cavity of the cylinder. The experimental data were sparse making it difficult to draw statistically sound conclusions but generally the data support the conclusion that fracture is enhanced when pressurized fluid is allowed to enter the crack. Time to failure and average crack velocity were used to compare numerical predictions with experimental data. Both the numerical computations and limited experimental results support the conclusion that the inclusion of pressure within a developing crack enhances crack propagation and should be considered in fluid-driven shock problems.

Degree Name

Mechanical Engineering

Level of Degree

Doctoral

Department Name

Mechanical Engineering

First Committee Member (Chair)

Dr. Yu-Lin Shen

Second Committee Member

Dr. Howard Schreyer

Third Committee Member

Dr. Joseph Bishop

Fourth Committee Member

Dr. John Stormont

Fifth Committee Member

Dr. Deborah Sulsky

Document Type

Dissertation

Language

English

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