stress in sheet metal bend

Jerry made a very good point. SW can only use tetrahedral elements as solid mesh and its 2 / 2.5 D mesh triangle elements. In this model, the element distortion is very large, so the tet / tri element needs to be very small so that the element does not crash.

Figure 1.2.2: Bending - Term and shape ductility of curved sheet metal plays a very important role. When ductility is low, the minimum bending radius is large. Likewise, the biaxial stress state in the curved region also reduces the ductility of the outer fiber. As the plate thickness ratio (w / t) is larger, the state of biaxial stress can be expected. When w / t reaches 8, the biaxial state is reached. Larger w / t ratios reduce the critical strain required for fracture. As a result, the bending radius increases. Since the stress condition along the edge is more biaxial than the central part, cracks occur at the end of the narrow part. Upon receiving a large bending radius, the central part undergoes more biaxial stress conditions, so the wider sheet cracks in the center. To increase the minimum radius, polish or grind the sheet

The outer surface of the curved sheet is called the minimum bending radius. It is usually expressed in thickness t. The following table shows the minimum radius of some materials. Table 1.2.1: Minimum curvature radius material Please bend. To obtain a representation of the minimum bend radius, the true strain of the material during the uniaxial tensile test at break can be equal to the bending strain. Ln (Ao / Af) = ln (1 + e) ​​= ln (1+)

Bending is a common manufacturing method for processing metal plates. Normally it is done with a bending machine, but a vibration bending machine is also used. In this machine, the curved material is bent with respect to a predetermined angle. Linear bending occurs in bending operation, and curved bending occurs in shape manipulation. In order to restore the residual stress of the stamped workpiece, heat treatment is usually carried out. The heat treatment can heat the metal to the recrystallization temperature, which will readjust the particles in the metal. By heat treating the metal, finer crystal grains can be obtained, so that cracks can be reduced and cured. The following describes the process heat treatment of the blade.