Laser shock peening

Abstract

Abstract Elastic-plastic transformations together with or separately of polymorphic phase transitions are important for the theory of shock waves. Here we discuss changing a classification consisting from elastic, split elastic-plastic, and pure plastic shocks. The split shocks means that there are two jumps: the elastic precursor and plastic shock, and that the elastic jump is independent relative to plastic one. In the split regime the precursor moves with elastic speed of sound overrunning the plastic jump and going further and further ahead relative to plastic jump as time proceeds and becoming weaker and weaker. We oppose the split shock to the one-wave (1W) two zones (elastic and plastic—2Z) shock (1W2Z shock). The 1W2Z wave propagates as whole (therefore one-wave), the plastic shock dynamically supports the elastic one, and the average distance between the jumps does not change in time. The powerful elastic shocks (their amplitudes are much higher than are usually suggested for elastic shocks) were found in experiments with femtosecond laser pulses and confirmed in large scale molecular dynamics (MD) simulations. The observation of the 1W2Z shocks is another important finding coming from MD. The report is devoted to lasers, shocks, and applications. In the second part of the report the generation and propagation of the shocks created for laser shock peening by lasers with ultrashort or nanosecond pulses are considered.