Comparison between Stereo Optical Strain Measurements and Finite Element Results in Stress Concentration Zones

Abstract

Experimental testing and deformation measurements during static loading in areas with high gradients are usually accompanied by uncertainties and inaccuracies of the applied methods. Comparison between different experimentally determined deformations and numerical calculation results of deformations at the determined measured points could be used to determine sensitivities and suitability of the particular measurement method for small deformations and pronounced levels of plastification. The paper presents analysis of combined deformation measurement methods with strain gauges and stereo-optical methods near the fatigue crack on the specimen during tensile loading. The results show that strain gauges are suitable for measurements at smaller deformations as applied for monitoring deformations during fatigue crack propagation. The stereo optical methods are suitable for measurements when significant elastic deformations occur, i.e. near the yield point, during static testing with plastic deformations and material fracture.

Keywords

• crack propagation
• digital image correlation
• fatigue
• fatigue crack growth rate
• finite element method
• stereo-optical measurements