Shot peening is one of the most effective surface strengthening treatment technologies in which compressive residual stresses are induced beneath the specimen surface. Effects of various factors on ...the distribution of residual stress profile induced by shot peening have been investigated by many researchers. However, initial residual stresses are one of the important factors which affect the shot peening residual stress.
This study is aimed to present comprehensive numerical and experimental study on the effect of initial residual stresses on the shot peened specimen. Initial residual stresses were induced using a four-point bending rig and grinding. Incremental center hole drilling (ICHD) technique was employed to measure residual stresses on bent, ground, shot peened, bent plus shot peened and ground plus shot peened specimens. Numerical analyses of these processes were performed to provide quantitative comparison of different combinations of residual stresses. The comparison with experimental results helped to have a better understanding on how shot peening residual stresses were redistributed. Furthermore, the surface hardness was measured for all specimens.
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•Redistribution of residual stresses by shot peening has been studied experimentally and numerically.•Finite element analyses of random shot impacts provided were combined with bending and grinding simulations.•Interesting results were obtained on how the shot peening stresses redistribute tensile or compressive initial stresses.•Residual stresses for all cases were experimentally measured.
•A size-dependent energy release rate for notched beams has been developed.•The energy release rate of notched beams under three-point bend condition has been formulated.•The energy release rate is a ...function of the ratio of the length scale to beam depth.•The results are in good agreement with the experimental observations.•The energy release rate of the Timoshenko model is greater than Euler–Bernoulli one.
The modified couple stress theory is employed in this paper in order to formulate the size-dependent strain energy release rate of Euler–Bernoulli and Timoshenko notched beams. As a case study, the normalized energy release rate of the aforementioned beams has been developed for three-point bending as a function of the ratio of material length scale parameter to the beam depth. The results of the current model are compared to the experimental data. The good agreement between the present results and the experimental values indicates that the current model can be successfully applied to evaluate size dependent energy release rate of structures.
► Fractography of the fracture surface indicates that fatigue is the most probable cause of failure. ► Analysis of the loading conditions indicates that the bolts are under multiaxial fatigue. ► ...Fatigue analysis by finite element modeling demonstrates that six critical nodes have the highest stress amplitude. ► Fatigue life for the most critical node is obtained as 3.63 million cycles or 593
h.
Fatigue failure of holding U-bolt of a cooling fan blade is analyzed. Fractography of the fracture surface reveals the characteristics of a fatigue fracture. Finite element modeling is used for stress analyzing. Analysis of the loading conditions indicates that the bolts are under multiaxial fatigue. Effective alternating and mean stresses are obtained based on the multiaxial fatigue criteria. By using the modified Goodman approach and considering the notch effect, effective stress amplitude, is obtained for all nodes. The highest stress amplitude is obtained at six critical nodes. Fatigue life for the most critical node is determined as 3.63 million cycles.
This paper presents an analytical model to predict the residual stress distribution induced by Shot peening. The analytical approach is based on the work of Shen and Atluri (2006) 18 with some ...modifications. The modifications are related to the elasto-plastic unloading of shot impingements, friction coefficient effect and the fraction of kinetic energy transmitted to the treated material. In order to predict more realistic residual stresses, the elasto-plastic unloading phase of shot impacts is modeled using two nonlinear kinematic hardening models considering the Bauschinger effect. Moreover, the effect of the Coulomb friction between target surface and shots is evaluated. For this purpose, the interior stresses caused by tangential tractions of friction force are determined analytically. In this work, the effects of friction coefficient, hardening model in loading and unloading phases, the offset of determination of the yield points and the Bauschinger effect on the residual stress distribution are taken into account. Experiments are carried out on DIN 1.6582 medium carbon steel to validate the results obtained from the analytical model. The results of the comparison indicate that the analytical relations agree well with the experimental data.
