Optimal Process Planning for Laser Forming of Doubly Curved Shapes

Abstract

There has been a considerable amount of work carried out on two-dimensional laser forming. In order to advance the process further for industrial applications, however, it is necessary to consider more general cases and especially their process planning aspect. This paper presents an optimal approach to laser scanning paths and heating condition determination for laser forming of doubly curved shapes. Important features of the approach include the strain field calculation based on principal curvature formulation and minimal strain optimization, and scanning paths and heating condition (laser power and scanning velocity) determination by combining analytical and practical constraints. The overall methodology is presented first, followed by more detailed descriptions of each step of the approach. Two distinctive types of doubly curved shape, pillow and saddle shapes are focused on and the effectiveness of the proposed approach is validated by forming experiments.

3D laser-forming strategies for sheet metal by geometrical information

“…Hutterer and Hagenah [5] applied laser forming to flattening non-circular dents with a pulsed laser and Bartkowiak et al [6] conducted experiments on the effect of an elliptical arc scan strategy and presented a laser formed hybrid cylinder part. Liu and Yao [7] made considerable progress on 3D laser-forming area. They obtained a principal strain field by the optimal development algorithm, and with the help of a FEM database they successfully determined laser-scanning paths and process parameters.…”

Analytical investigation of structurally stable configurations in shape memory alloy-actuated plates

“…In this work, where the intrinsic material actuation is provided by the SMA constituents of the plates, the determination of the thermal input that would induce the morphing of the plate towards specific shapes is pursued. Similar problems have been addressed for laser forming of doubly curved shapes (Liu et al, 2004) and for SMA-based plates (Peraza-Hernandez et al, 2014a) under iterative optimization frameworks. With the present novel approach, the applied conditions (e.g., the temperature field) that will morph Fig. 14.…”

“…One approach for the achievement of changes in Gaussian curvature in plate structures is through the generation of inhomogeneous in-plane extensional/shear strain fields throughout their middle surface (Seffen and Maurini, 2013;Fernandes et al, 2010;Yu et al, 2000;Liu et al, 2004;Ryu and Shin, 2006). Relatively moderate to large rotations in plate structures entail a coupling between bending and in-plane extension/shear.…”

Application of laser peen forming to bend fibre metal laminates by high dynamic loading

“…Compared with conventional forming process, laser forming of sheet metal requires no mechanical contact of hard tooling.Production of complex shapes can be achieved through the specified scanning strategy of laser spots. Therefore, this approach has many technological advantages including design flexibility, producing complex shapes, and reducing the cost of forming process when low-to medium-volume production or prototyping is concernedin industry (Liu et al, 2004;Vollertsen, 1994).Laser forming, usually indicating laser thermal forming, utilizes a defocus laser source to bend sheet metal parts by introducing thermal stresses across the thickness.Edwardson et al presented that this process also allowedto form FMLs with sharp radii by introducing the thermal stress in the cover metal layer (Carey et al, 2010). However, under the high thermal exposure and forced cooling, the unintended delamination and material failure of burning and fibre cracking make it hard to maintain material properties of shaped parts.…”