An analytical model for predicting residual stress in shot peening with strain energy method.

In this study a model by novel analytical approach is developed and experimentally verified for shot peening residual stress distribution. The residual stress field induced by single shot impact is calculated by using Glinka-Molski energy-based method and kinematic hardening model. The formulation of the compressive residual stress (CRS) distribution is often based on plane strain or plane stress. It can be determined from the derived relation presented in this paper, the final residual stress in the full coverage conditions is the average of the two strain and stress plane expressions proposed by previous researchers. The distribution of residual stress is one of the key differences between the profiles produced by the results of the current model. There is a significant distinction between surface residual stress and maximum CRS, because the CRS profile near the surface is more curved compared to profiles obtained in earlier analytical models. The experimental data obtained by XRD analysis indicate the correctness and precision of the current model. Another goal of this study is to increase the fatigue life of GTD-450 stainless steel by shot peening at two different peening intensities. The fatigue life of samples were obtained by rotary bending test. Analytical results that confirmed by experimental findings shown bigger maximum compressive residual stresses occurred in higher shot peening intensities. This incident can improved fatigue life by deeper plastically deformed layer.

Study of modal properties of a typical ultrasonic stack with numerical and experimental modal analysis.

In the present study, the modal properties of an ultrasonic stack are investigated. The ultrasonic stack comprises a wide horn. The horn of the ultrasonic stack is designed with the genetic algorithm. The objectives of the problem are: the main longitudinal mode shape frequency should be similar to the frequency of the transducer-booster, and this mode has adequate frequency separation from other modes. The finite element simulation is used to calculate the natural frequencies and mode shapes. An experimental modal analysis using the roving hammer method is utilized to detect real natural frequencies, and mode shapes and verify the simulation results. Based on the simulation results and due to the complex structure of the ultrasonic stack, three different setups are utilized for the experimental modal analysis. The results show that the experimental test identifies all detected modes from the finite element simulation. Also, the frequency difference between the simulation and experimental results is less than 1% in most cases. The average frequency difference between the simulation and experimental results is 1.42%. The simulation frequency of the main longitudinal mode is 14 Hz (0.07%) lower than the experimental result.