Laser shock peening (LSP) is used to enhance surface quality of the metallic structures by the generation of compressive residual stresses on it. This work studies the effect of the main LSP parameters on residual stress fields by the finite-element method. The specimen under investigation is a square plate with a thickness of 3 mm made of Ti-6Al-4V. The performed analysis enhances understanding of LSP application to structures manufactured from this material and this information can be useful for a choice of optimal peening parameters. The effect of the spot size and shape, the pulse energy, the number of peen layers, overlapping of spots and temporal variation of the mechanical pressure induced by plasma is considered and analyzed. A 3D finite-element model based on the Johnson-Cook constitutive relation is developed and verified by the results of residual stress measurements performed for the LSP-treated samples under different conditions. From the obtained results the following main conclusions can be drawn: pulse energy provides the more significant effect although the resulting residual stresses profile tends to some saturation curve; temporal pressure pulse shape and its total duration also substantially alter the residual stress field; the least significant parameter is the spot shape.

Laser shock peening (LSP) is a relatively novel and promising surface hardening method. An absorbing layer, which is needed to protect the specimen surface from undesirable thermal effects caused by laser irradiation, should be considered as one of many varying parameters. The physical characteristics of the coating and its adhesion to the specimen surface can significantly influence the result of LSP. In this study, three commonly used absorbing coatings, namely black polyvinylchloride tape with a sticky layer, aluminum foil, and black alkyd paint were used to cover three-millimeter-thick plates of the Ti-6Al-4V titanium alloy with globular or lamellar microstructures. LSP of one side of the plates was carried out with a power density of 10 GW/cm². The hole drilling method was used to evaluate residual stresses. The aluminum foil was found to be the optimal option for LSP of the Ti-6Al-4V titanium alloy. Microstructural investigations carried out using EBSD analysis suggested that no significant reduction in grain size, twinning, or dislocation density growth occurred as a result of LSP irrespective of the initial structure.

The exhaustion of constructive ways for increasing the service life of parts has led to the development of new methods which can improve their material properties during operation under various loading conditions. Laser shock peening (LSP) induces compressive residual stress field which prevents fatigue crack initiation and propagation in components. Characteristics of laser impact and treatment patterns play an important role in efficiency of LSP application for improvement of fatigue properties. This work is devoted to the experimental examination of two LSP patterns to reveal the most optimal scheme from fatigue live improvement point of view. Proposed LSP pattern allowed one to increase the fatigue life of specimens with semi-circular notch by an order of magnitude. The numerical simulation of the LSP was performed to visualize the residual stress field of treated specimen after loading and to give the interpretation of the experimentally observed improvement of fatigue life.

Effect of laser shock peening on the fatigue life of an OT4-0 titanium alloy is studied. Laser peening is carried out using a Q-switched Nd:YAG laser operating at a pulse repetition rate of 10 Hz. It is suggested by the analysis of the effect of various laser treatment parameters on the magnitude and distribution of residual stresses over the sample thickness that an optimal type of laser shock treatment makes it possible to create a compressive residual stress region whose depth reaches up to 1 mm and whose maximum value is 600 MPa. The results of the study of the fracture surface structure show that the fatigue fracture mechanism changes, while the service life of samples significantly increases during both low- and high-cycle fatigue after laser shock peening.

The paper is devoted to the development of the method of laser shock peening (LSP) of metals. To optimize the mode of LSP for Ti-6Al-4V specimens a deep learning model for predicting residual stresses by laser shock peening was developed. A numerical-experimental method was used to carry out the model training, in which an experimental study of the effect of different processing mode on the depth and distribution of residual stresses was carried out. The Johnson-Cook model was used as the governing relationship for modeling the dynamic deformation process. At the second stage, the problem of static equilibrium of a body with a plastically deformed area was numerically solved to determine residual stresses. The results of research on determination of the optimal configuration of the deep learning model showed that when using sinusoidal activation function of the neural network with 4 hidden layers and the number of neurons 10, the best level of accuracy in solving the problem is achieved. The obtained model allows us to optimally determine the LSP mode according to the given limitations of values and depth of residual stresses.