Crack Propagation Analysis of Compression Loaded Rolling Elements

Area of Science:

• Mechanical Engineering
• Materials Science
• Tribology

Background:

• Thermoplastic cylindrical bearing elements are prone to crack propagation from internal defects.
• Crack propagation occurs under complex mixed-mode loading conditions (Modes I, II, and III).
• The interplay of these loading modes changes dynamically during element rotation.

Purpose of the Study:

• To analyze crack propagation from internal defects in thermoplastic cylindrical bearings.
• To develop a model for stress intensity factor dependency on crack length and internal voids.
• To evaluate the influence of manufacturing defects and crack face friction on crack behavior.

Main Methods:

• Development of general parametric equations to describe stress intensity factors.
• Modification of the model to include a void simulating a manufacturing defect.
• Analysis of mixed-mode crack propagation under combined tensile and shear loading.

Main Results:

• The presence of a void significantly impacts stress intensity factor values.
• This void influence diminishes as the crack propagates away from the defect.
• Friction between crack faces was found to have a negligible effect on stress intensity factors.

Conclusions:

• The developed model provides a simplified approach to predict bearing element lifetime.
• Results can be directly applied for lifetime calculations, avoiding complex finite element simulations.
• Understanding defect influence is crucial for enhancing the durability of thermoplastic bearing elements.