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Computation of dynamic stress intensity factors by the time domain boundary integral equation method—II. Examples

✍ Scribed by Sambi R. Mettu; James W. Nicholson


Publisher
Elsevier Science
Year
1988
Tongue
English
Weight
955 KB
Volume
31
Category
Article
ISSN
0013-7944

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✦ Synopsis


Application of the direct time domain boundary integral equation method (BIEM) to the solution of a number of elastodynamic crack problems is presented. The analytical and numerical formulation has been detailed in part I. In this part II we give the details of some examples solved using the time domain BIEM. The examples considered include those involving semi-infinite cracks and finite length cracks in infinite bodies and finite bodies with finite cracks as well as time dependent loading. The numerical results obtained are compared with available analytical and numerical results. It is found that both of the types of elements discussed in part I model the crack tip displacement fields well when no reflected waves are involved. The QL element is slightly more accurate but requires significantly more computer CPU time and memory. An example involving a discontinuously loaded semi-infinite crack displays the wave propagation features quite well using both types of elements. The effects of finite cracks and wave interaction with the finite boundaries of the specimen are also found to be modeled quite well using the CC element but some oscillation in the computed SIF values at later times is observed when these problems are solved using the QL elements. In the case of a finite crack in an infinite body the discontinuity in the slope of the SIF history curve predicted by Thau and Lu is successfully reproduced by the present BIEM whereas it appears that most other numerical results published so far do not seem to be able to model this feature well. For each case some typical boundary meshes used and the stress intensity factor history is presented using the two types of elements and different time step sizes where appropriate. Values of the computer memory and the execution time required are presented in the form of graphs. It is concluded that the time domain BIEM is a viable technique for solving dynamic crack problems using the CC elements but requires further investigation of the numerical oscillations at later times when the QL elements are used.


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