The Fatigue Surface Cracks Growth Model Taking into Account Plastic Deformations for a Cylinder of a Low-speed Long-stroke Compressor

The article dwells on a model of a surface crack growth for a cylinder of a long-stroke compressor taking into account plastic deformations in a crack tip and a type of loading. We have obtained experimental data for cross-shaped samples made of engineering material; the samples have been used to study the effect of biaxial loading on a crack growth rate. The crack growth has been examined comparing the results obtained under monoaxial tension and under biaxial compression-tension. The fracture in a fatigue crack tip is presented as a combination of brittle fracture on a crack tip and as a ductile fracture in a propagation zone of plastic deformations. The finite element method with linear hardening in a zone of plastic deformations have been used to explore a stress state in a crack zone. The formula is proposed to determine the growth rate of fatigue cracks taking into account brittle and ductile stress parameters in the crack tip.