Journal article
On the determination of material parameters in crack initiation laws

Publication Details
Huang, X.; Brückner-Foit, A.
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Fatigue and Fracture of Engineering Materials and Structures
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Crack initiation along slip bands can be described by the Tanaka-Mura relation and its extensions. These relations are based on dislocation theory and determine the number of load cycles to reach a critical dislocation density for a given value of the resolved shear stress along the potential crack path. An important material parameter in these relations is the critical shear stress which is a threshold value for crack initiation, i.e. the number of cycles to crack initiation becomes infinitely high if the resolved shear stress along the potential crack path stays below this threshold value. This critical shear stress is determined using a database for microcrack initiation, microcrack growth, and coalescence obtained with a martensitic steel. The number of cracks per unit area, the so-called crack density, was derived from this database as a function of the number of load cycles. These experimentally observed values of the crack density are compared to values obtained by simulating the crack initiation process using a random cell structure as a mesoscopic unit cell. A best fit is obtained for values of the critical shear stress between 110 and 160 MPa with the uncertainty both related to simplifications in the model and to limitations of the experimental analysis.

Last updated on 2019-01-11 at 16:05