The development of mongrel singular element with J-integral and the toughness test for Al 7075-T6 wing spar

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Journal of the Korea Institute of Military Science and Technology 1998;1(1):154-165.

J적분을 첨가한 mongrel 특이요소 개발 및 Al 7075-T6 wing spar파괴인성 실험

강치행

군사과학대학원 항공우주공학과

Abstract

In this paper, the mongrel singular element with 6 node triangle and 8 node quadrilateral element with J-integral are developed and applied to the various plane crack problems for the isotropic material. The convergence nature is excellent for various crack size with even coarse mesh using the direct method. But the results of the mongrel element with J-integral are worse than the former's ones. Fracture tests were conducted on precracked CT specimens. Results show that, for 7075-T6 aluminum wing spar materials, the fracture toughness is 31.06 ksi.inch $frac{1}{2}$ in the L-T direction.