Papers by Author: Hans A. Richard

Abstract: This article deals with the development of functional graded materials which is pursued by the collaborative research centre Transregio 30. The functional gradation is produced by a thermo-mechanical production process and is characterized by different fracture mechanical specific values. Because cracks are by all means responsible for failure of structural elements crack growth has to be considered during the development of these materials. In this contribution simulations of crack growth which were carried out with the system ADAPCRACK3D are presented to illustrate the influence of a material gradation on crack growth.

Abstract: In this paper the rather complex 3D fatigue crack growth behaviour in a shaft with a quarter-circular crack under torsion is investigated by the aid of the programme ADAPCRACK3D and by application of a recently developed 3D fracture criterion. It will be shown that the computationally simulated results of fatigue crack growth in the FE-model of the shaft are in good agreement with experimental findings for the development of two anti-symmetric cracks, which originate from the two crack front corner points, that is where the crack front intersects the free surface of the cylindrical laboratory test-specimens. Consequently, also for this case with a rather complex 3D crack growth of two anti-symmetric cracks, the functionality of the ADAPCRACK3Dprogramme and the validity of the proposed 3D fracture criterion can be stated.