Hill Engineering has developed and validated a computational design tool that predicts the residual stress and distortion caused by processes that provide compressive residual stress. This software, ERS-toolbox®, is the product of more than a decade of meticulous study and collaboration with government and private industry.

ERS-toolbox® was successfully applied for design and analysis of a structural retrofit to the F-22 that used laser shock peening to restore performance and extend the service life of the F-22 airframe. ERS-toolbox® offers a fast and flexible approach to design an optimal process for the desired level of compressive residual stress benefit while managing potential detriments from tensile residual stress and process-induced distortion.

The flow chart illustrates how ERS-toolbox® complements OEM design and analysis information to provide estimates of performance benefits from a given residual stress treatment plan. This capability is a key for residual stress engineering of fatigue life extension processes, allowing virtual trials of treatment processes, process parameters, and processed area. These trials enable rapid and cost-effective design of residual stress treatments that meet customer goals.

Flow chart showing the role of ERS-toolbox® in analysis that estimates the effects of residual stress treatments

Recently, ERS-toolbox® was used to design a laser shock peening treatment for an aircraft engine compressor airfoil that meets objectives for residual stress, in terms of benefits of compression and detriments from tension and part distortion. With laser shock peening (and other compressive stress treatments) the residual stress and distortion produced are functions of process variables, including the processed area and the process intensity. As part of the design program, ERS-toolbox® was demonstrated over a range of process intensity and processed area. The diagram shows ERS-toolbox® estimates of the effect of laser shock peening, comprising blade twist (superposed on original geometry) and residual stress (from compression in blue to tension in red). Deformation and residual stress estimates were found to be very useful when validated against dimensional and contour method measurements.

Predicted residual stress and distortion of a high pressure compressor airfoil using the ERS-toolbox software

The ERS-toolbox® drives innovations in fatigue-life extension by enabling design of processes that provide compressive stress, including shot peening, laser peening, and hole cold expansion.

Further information on residual stress engineering
Fatigue Life Extension
Quality Control
Distortion Engineering