This work presents experimental studies with numerical modeling, aiming at the development of guidelines for shaping aluminum alloy AA6111-T4, t = 1.5 mm thick, with the use of a shear-slitting operation. During the experimental tests, parametric analyses were conducted for the selected material thickness. For the purposes of the material deformation’s analysis, a vision system based on the digital image correlation (DiC) method was used. Numerical models were developed with the use of finite element analysis (FEA) and the mesh-free method: smoothed particle hydrodynamics (SPH), which were used to analyze the residual stress and strain in the cutting zone at different process conditions. The results indicate a significant effect of the horizontal clearance between knives on the width of the deformation zone on sheet cut edge. Together with the clearance value increase, the deformation zone increases. The highest burrs on the cut edge were obtained, when the slitting speed was set to v = 17 m/min, and clearance to hc = 6%t. A strong influence was observed of the horizontal clearance value at high slitting speeds on burr unshapeliness. The most favorable conditions were obtained for v = 32 m/min, hc = 0.062 mm, and rake angle of upper knife for α = 30°. For this configuration, a smooth sheared edge with minimal burr height was obtained.
In this study the process of burnishing rolling is considered as a geometrical and physical boundary and initial value problem, with unknown boundary conditions in the contact area. 3D dynamic explicit method for burnishing rolling process with taking into account surface after turning (as previous treatment) under ANSYS/LS-DYNA environment was established. The analysis covered surfaces characterized by vertical angles of the asperities in range: 60°÷150°. The simulation results (i.e. surface deformation, states of strain and stresses, depth of stress deposition) were evaluated. The influence of vertical angle of the asperities after turning process on the states of stress and strain and the depth of its deposition are presented.
The shearing process such as the blanking of sheet metals has been used often to prepare workpieces for subsequent forming operations. The use of FEM simulation is increasing for investigation and optimizing the blanking process. In the current literature a blanking FEM simulations for the limited capability and large computational cost of the three dimensional (3D) analysis has been largely limited to two dimensional (2D) plane axis-symmetry problems. However, a significant progress in modelling which takes into account the influence of real material (e.g. microstructure of the material), physical and technological conditions can be obtained by using 3D numerical analysis methods in this area. The objective of this paper is to present 3D finite element analysis of the ductile fracture, strain distribution and stress in blanking process with the assumption geometrical and physical nonlinearities. The physical, mathematical and computer model of the process are elaborated. Dynamic effects, mechanical coupling, constitutive damage law and contact friction are taken into account. The application in ANSYS/LS-DYNA program is elaborated. The effect of the main process parameter a blanking clearance on the deformation of 1018 steel and quality of the blanks sheared edge is analyzed. The results of computer simulations can be used to forecasting quality of the final parts optimization.
Paper presents the modelling of the contact problem in the technological processes. Technological processes were considered as a geometrical and physical boundary and initial value problem, with unknown boundary conditions in the contact zone. An incremental model of the contact problem between movable rigid or elastic body (tool) and elastic/visco-plastic body (object) in updated Lagrange formulation, for spatial states (3D) was considered. The incremental functional of the total energy and variational, non-linear equation of motion and deformation of object on the typical step time were derived. This equation has been discretized by finite element method, and the system of discrete equations of motion of objects was received. For solution of these equations the explicit or implicit methods was used. The applications were developed in the ANSYS/LS-Dyna system, which makes possible a complex time analysis of the states of displacements, strains and stresses, in the workpieces in technological processes. Application of this method was showed for examples the modelling and the analysis of tensile test [1 and technological processes of metal forming [1-.
The article presents an innovative method of reducing welding distortions of thin-walled structures by introducing structural and technological changes. The accuracy of the method was demonstrated on the example of welding the stub pipes to the outer surface of a thin-walled tank with large dimensions, made of steel 1.4301 with a wall thickness of 1.5 × 10−3 (m). During traditional Gas Tungsten Arc Welding (GTAW), distortions of the base are formed, the flatness deviation of which was 11.9 × 10−3 (m) and exceeded the permissible standards. As a result of structural and technological changes, not only does the joint stiffness increase, but also a favorable stress state is introduced in the flange, which reduces the local welding stresses. Numerical models were developed using the finite element method (FEM), which were used to analyze the residual stresses and strains pre-welding, in extruded flanges, in transient, and post-welding. The results of the calculations for various flanges heights show that there is a limit height h = 9.2 × 10−3 (m), above which flange cracks during extrusion. A function for calculating the flange height was developed due to the required stress state. The results of numerical calculations were verified experimentally on a designed and built test stand for extrusion the flange. The results of experimental research confirmed the results of numerical simulations. For further tests, bases with a flange h = 6 × 10−3 (m) were used, to which a stub pipe was welded using the GTAW method. After the welding process, the distortion of the base was measured with the ATOS III scanner (GOM a Zeiss company, Oberkochen, Germany). It has been shown that the developed methodology is correct, and the introduced structural and technological changes result in a favorable reduction of welding stresses and a reduction in the flatness deviation of the base in the welded joint to 0.39 × 10−3 (m), which meets the requirements of the standards.