Modeling of Fatigue Crack Initiation in Wire-Bonds Using a Novel Approach of Strain Gradient Theory

Martin Lederer; Golta Khatibi; Dominik Thuiner; Herbert Danninger

doi:10.4028/www.scientific.net/KEM.592-593.246

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Damage Mechanics and Critical Plane Approach to Multiaxial Fatigue
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Modeling of Fatigue Crack Initiation in Wire-Bonds Using a Novel Approach of Strain Gradient Theory
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HomeKey Engineering MaterialsKey Engineering Materials Vols. 592-593Modeling of Fatigue Crack Initiation in Wire-Bonds...

Modeling of Fatigue Crack Initiation in Wire-Bonds Using a Novel Approach of Strain Gradient Theory

Abstract:

The fatigue life of wire-bonds was measured with use of a 20 kHz ultrasonic testing system. Thereafter, the experiments were interpreted by Finite Element Analysis. First, simulations were performed according to classical continuum mechanics. They predicted stress concentrations at the location where crack initiation was found experimentally. However, the stress concentrations showed the characteristics of stress singularities even for loading cases corresponding to the regime of very high cycle fatigue, i.e. fairly moderate loads. In subsequent simulations, the singularities of stress concentrations could be removed on the basis of a newly developed version of strain gradient elasticity, resulting in predictions that agreed well with experimental results.