Tilting separation simulation and theory verification of mask projection stereolithography process

Purpose: This study aims to accurately simulate the tilting separation process of mask projection stereolithography (MPSL) and verify the tilting theory. Design/methodology/approach: The finite element separation models of MPSL 3D printing process were established. The established models simulated both tilting and pulling-up separation process by changing the constraints and boundary conditions. The bilinear cohesive curves were used to define the separation interface. The stress distribution of the cured part and FEP film at different times during the whole separation process was extracted. Different orientations of pulling-up and tilting were also compared for stress distribution. The stress change was analyzed for the center and edge points of the upper surface of cured part. Findings: The results showed that the stress increased with the separation speed, and the stress at the edge position of exposure area was greater than the internal position. The tilting traction stress distribution was affected by the exposure area function and the velocity distribution. Alternation of the exposure area function changed the cohesive stiffness. The non-coincidence of the calculated traction stress with the input bilinear cohesive curve reflected the influence of the material properties and the separation methods. The high-speed side of tilting had fast separation and high traction stress. Originality/value: This study proposes a technical method for simulation tilting separation and verified the tilting theory. The cohesive zone model was proved applicable to the tilting traction stress calculation.