Influence of specimen thickness on the fatigue behavior of notched steel plates subjected to laser shock peening

• Published in: Optics and laser technology Vol. 101; pp. 531 - 544
• Main Authors: Granados-Alejo, V., Rubio-González, C., Vázquez-Jiménez, C.A., Banderas, J.A., Gómez-Rosas, G.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.05.2018; Elsevier BV
• Subjects: Crack initiation; Crack propagation; Distribution; Duplex stainless steels; Fatigue failure; Fatigue life; Finite element method; Fracture mechanics; Hole drilling method; Influence; Laser shock peening; Laser shock processing; Life extension; Mathematical analysis; Neodymium lasers; Peening; Plastic deformation; Plastic strain; Predictions; Residual stress; Size effects; Stainless steel; Steel plates; Strain distribution; Stress concentration; Stress distribution; Studies; YAG lasers; Fatigue life; Laser shock peening; Residual stress
• ISSN: 0030-3992; 1879-2545
• DOI: 10.1016/j.optlastec.2017.12.011

•Thickness affects significantly fatigue life of laser treated components.•The thinner the specimen the better the LSP benefit on fatigue life extension.•The thinner the specimen the higher the plastic strain produced by LSP.•Life extension up to 300% is experimentally observed on thin specimens with LSP. The influence of specimen thickness on the fatigue crack initiation of 2205 duplex stainless steel notched specimens subjected to laser shock peening (LSP) was investigated. The purpose was to examine the effectiveness of LSP on flat components with different thicknesses. For the LSP treatment a Nd:YAG pulsed laser operating at 10 Hz with 1064 nm of wavelength was used; pulse density was 2500 pulses/cm2. The LSP setup was the waterjet arrangement without sample coating. Residual stress distribution as a function of depth was determined by the hole drilling method. Notched specimens 2, 3 and 4 mm thick were LSP treated on both faces and then fatigue loading was applied with R = 0.1. Experimental fatigue lives were compared with life predictions from finite element simulation. A good comparison of the predicted and experimental fatigue lives was observed. LSP finite element simulation helps in explaining the influence of thickness on fatigue lives in terms of equivalent plastic strain distribution variations associated with the change in thickness. It is demonstrated that specimen size effect is an important issue in applying LSP on real components. Reducing the specimen thickness, the fatigue life improvement induced by LSP is significantly increased. Fatigue life extension up to 300% is observed on thin specimens with LSP.