Laser shock processing (LSP) involves laser-induced, liquid-confined plasma sending strong shock waves into target and thus imparting compressive residual stress into surface layer to improve fatigue performance.  Compared with mechanical shot peening, LSP offers a deeper layer of compressive residual stress, and is more flexible especially for irregular shapes.  It has been shown that LSP can improve fatigue life by 5 to 6 times. 

LSP was first discovered by Dr. Allen Clauer of Battelle Institute in 1960s but was not till last few years interest is renewed primarily because LSP requires powerful lasers to general several to tens GW/cm² laser intensity.  Prof. Fabbro’s group in France was responsible for many advances in LSP.  We at Columbia University have been carrying out projects on micro-scale LSP under NSF and other support and have been developing reliable prediction models and experimental results for micro-scale LSP. 

Micro-scale LSP (mLSP) uses micron-sized laser beam while most LSP work uses millimeter sized beam.  One-dimensional shock pressure model has been extended to two-dimensional.  Both bulk and thin film materials have been considered.  mLSP has potential applications in improving fatigue life of metallic MEMS components.  While most MEMS components are made of silicon, metallic contacts, coating and high aspect ratio components will benefit from mLSP.  The current issues in mLSP research include

More recently, LSP has been extended to LPF (laser peen forming), in which the target is shaped (say, bent) and at the same time imparted desirable residual stress on BOTH sides.  In mechanical bending, there is compressive residual stress on one side of the specimen only.  Lawrence Livermore National Lab has reported progress in LPF and our work focuses on using a micron-sized laser beam to effect LPF.

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