A considerable residual stress distribution can be produced while bending of parts. This stress distribution depends on material behavior. In this article, residual stress distribution has been determined through the thickness in beam bending. For three different models of elastic-plastic behavior, the stress distribution and maximum residual stress are derived analytically. The residual stress is compared for three different bending radii as a case study. Also, finite element analysis has been carried out for two material properties. The results show that material behavior has little effect on stress distribution for large value of bending radius. As the bending radius decreases, difference of stress distribution increases rapidly among three plastic behaviors. Comparing the results of finite element and analytical stress distribution shows good accuracy for suggested formulations.

Laser forming is an emerging manufacturing process capable of producing either uncomplicated and complicated shapes by employing a concentrated heating source. The heat source movement creates local softening, and a plastic strain will be induced during the rise of temperature and the subsequent cooling. This contactless forming process may be used for the simple bending of sheets and tubes or fabrication of doubly-curved parts. Different studies have been carried out over recent years to understand the mechanism of forming and predicting the bending angle. The analysis of process parameters and search for optimized manufacturing conditions are among the most discussed topics. This review describes the main recent findings in the laser forming of single and multilayer sheets, composite and fiber-metal laminate plates, force assisted laser bending, tube bending by laser beam, the optimization technique implemented for process parameters selection and control, doubly-curved parts, and the analytical solutions in laser bending. The main focus is set to the researches published since 2015.

Slitting method or crack compliance method is used widely for residual stress measurement in different geometries, materials and processes. In this article, roll bending process is selected as a case study which can create residual stress in manufactured parts. The slitting method is employed to determine the residual stresses in a roll-bent stainless steel 314 sample. The series expansion approach is used for residual stress calculation. The compliance matrix is determined by finite element analysis. The uncertainty analysis and average strain misfit are used as two criteria for selecting the best order of expansion. The results show that nine terms of Legendre basis function (L 2 -L 10 ) can calculate residual stress profile accurately. It is observed that a maximum of 117 MPa residual stress magnitude is induced to the sample. The sample was manufactured with 1.078 m curvature radius by three-roll bending process. The sample thickness was 10 mm. The average uncertainty for residual stress distribution through the slit is equal to 3.6 MPa, while the maximum value of uncertainty could be estimated to be about 21 MPa. The analytical residual stress is also calculated by assuming power law material behavior and compared with the experimental results. This comparison shows a good agreement between the experimental and analytical solution.

The laser beam can be used as a powerful tool for bending tubes and sheets by local heating and buckling mechanism. Herein, the bending of mild steel tubes is investigated by irradiation of the laser beam. To consider the effect of the interaction of process parameters despite previous research, six laser tube bending process parameters in different levels including laser power, scanning speed, laser beam diameter, irradiation length, number of irradiation passes, and irradiation scheme are selected and a set of 92 experimental tests is planned according to the response surface methodology (RSM). The tests have been carried out by using a continuous wave (CW) CO2 laser. The influencing parameters affecting the main bending angle and the lateral bending angle are determined. The effect of main process parameters and their interaction on the main and lateral bending angles are discussed. The axial irradiation scheme (AIS) creates a higher main bending angle compared to the circumferential scanning strategy. The results show that the main bending angle and lateral bending angle increase by increasing the laser power, irradiation length, and the number of irradiation passes and reducing the scanning speed and laser beam diameter. The main and lateral bending angles are determined by a regression equation with about 96% goodness of fitting. The results show that 1100 W laser power, 14.6 mm s−1 scanning speed, 4 mm laser beam diameter, 28.27 mm irradiation length, 1 pass of irradiation, and AIS lead to a simultaneous maximum bending angle of 1.80° and minimum lateral bending angle of 0.152°.

Laser forming is a powerful tool for fabricating complicated shapes economically. The pattern of laser movement (irradiating scheme) has an essential effect on the shaped form. In this article, the forming of a saddle-shaped surface will be investigated experimentally by the laser forming process. A spiral irradiating scheme is implemented to manufacture a saddle-shaped surface. The main idea of this study is the investigation of the simultaneous variations of the process parameters and their effect on the curvature of the final part. The process parameters of the study are the spiral pitch, number of spiral passes, and movement pattern (In-to-Out or reversely Out-to-In scanning path). The response surface methodology is selected for experimentation. The measurement of the deformation results shows that the deformations of laser-formed saddle-shaped surfaces decrease with an increase in the spiral pitch of the path. Additionally, the deformations of the saddle-shaped surface increase by increasing the number of spiral passes. The results demonstrate that the pattern movement has little effect on the deformations of laser-formed saddle-shaped surfaces and an Out-to-In spiral pattern movement is advised. At last, the proper input variables to obtain the maximum value of displacements for the saddle point are determined (10 mm spiral pitch, three spiral passes, and Out-to-In pattern movement).