Search

In order to achieve the change rule of the induced residual stress (RS) field after multipass ultrasonic surface rolling (USR), a mathematical model of the induced residual stress (RS) field after multipass ultrasonic surface rolling is first established. Then, the coupling mechanisms of the RS field after dual-pass USR and multipass USR are analyzed, respectively. Subsequently, a finite element (FE) model is established, and the influence of the interval between two adjacent rolling paths L S is investigated. Finally, both the mathematical model and the FE model are experimentally verified. The results show that both the mathematical model and the FE model can predict the RS field after multipass USR. Two adjacent RS fields will couple with each other in their overlapping regions. For a relatively small interval L S , the RS field after multipass USR can be fully coupled, so as to form a uniform compressive RS layer. In this study, when L S = 0.05 mm, the values of the surface compressive RS, the maximum compressive RS, the depth of the maximum compressive RS, and the depth of the compressive RS layer reach 426.71 MPa, 676.54 MPa, 0.05 mm, and 0.54 mm, respectively. [ABSTRACT FROM AUTHOR]

Water jet peening (WJP) is a surface enhancement technique that can use the impact pressure to induce compressive residual stress in the narrow concave area of metal components. For WJP on the inclined surface, this research reveals the impact pressure evolution and the forming mechanism of compressive residual stress field (CRSF). Mathematical models of predicting the critical inclined angle θc and the maximum water hammer pressure Pm are developed. Besides, a 3D dynamic finite element model of WJP is developed. Then, the simulation model is verified by the experimental results of the inclined surface. Moreover, the influence of parameters such as inclined angle θ, jet velocity v, and jet diameter d on θc, Pm, and CRSF is investigated by simulation. The results indicate that Pm essentially determines the CRSF, and WJP parameters indirectly affect the CRSF by changing Pm. v determines θc, and θc increases with increasing v. θ and v determine Pm, and Pm decreases with increasing θ while increases with increasing v. The magnitude and depth of CRSF decrease with increasing θ while increases with increasing v. But d only affects the depth of CRSF, which increases with increasing d. [ABSTRACT FROM AUTHOR]

The water jet peening (WJP) technology can induce compressive residual stress (RS) in metal surfaces and, thus, improve the fatigue life of components. In this paper, a mathematical model is proposed for calculating the RS induced by WJP. To validate the proposed mathematical model, experimental and finite element simulation verifications were carried out on Al6061-T6. The distribution of RS along the depth direction, the maximum compressive RS, and the depth of the compressive RS layer were also investigated based on the mathematical model. Results showed that the error of maximum compressive RS between the mathematical model and experiment was within 9% under a jet pressure of 60 MPa, and the error of depth of the compressive RS layer between the mathematical model and experiment was within 13% under a jet diameter of 0.3 mm. Hence, the mathematical model is reliable and accurate. The maximum compressive RS increases with the increase in jet pressure, and the depth of the compressive RS layer approximately linearly increases with the increase in jet diameter. [ABSTRACT FROM AUTHOR]