Fatigue Testing Guidelines

Author:  Dave Breuer | Curtiss-Wright Surface Technologies & Charlie Li | DANTE Solutions
Source:  The Shot Peener magazine, Vol 33, Issue 4, Fall 2019
Doc ID:  2019041
Year of Publication:  2019
Abstract:  
These guidelines are a collaboration between Dave Breuer (Curtiss-Wright Surface Technologies) and Charlie Li(Dante Solutions). Since most shot-peened components receive heat treatment, Mr. Breuer and Mr. Li work together to provide solutions for customers interested in residual stress from both processes. When qualifying shot peening (SP), engineers utilize data such as computer simulation and fatigue testing in a controlled setting. This data is faster, relatively inexpensive and useful to making decisions on SP. This lower cost data may qualify the SP so when expensive field testing occurs, it verifies what was already proven on subscale components. The intention of this article is to discuss guidelines for proper laboratory fatigue testing. The following items will be discussed in greater detail: • Specimen Geometry • Accelerated Testing • Stress Gradients Specimen Geometry Most fatigue failures occur from bending or torsional loading. Bending/torsion leads to crack initiation at the surface as the applied stress is highest for both types of stress. Shot peening is a surface treatment ideally suited for surface-initiated failures.