As in the experiment, the three-point bending finite element model includes three rollers (two supporting rollers and one pressing roller) and a rectangular section specimen. The roller finite element model is built using 4-node 3-D bilinear rigid quadrilateral (R3D4) element. The length of the roller is 20 mm and the diameter is 10 mm. The minimum size of element is 1mm for both roller and specimen. The total number of elements are 3462 and 18000 for roller and specimen, respectively.
Three rollers and specimen are assembled in the simulation of three point bending test as shown in Figure 4-5. The material properties are defined as same as the tensile simulation. The supporting rollers are applied full constrain while the pressing roller is applied axial constraint. The specimen is placed on the two supporting rollers. Vertical displacement boundary conditions are applied for the pressing roller. The surface-to-surface contact between the roller and specimen is defined as shown in the table 4-2.