Effect of support force on quality during double-sided incremental forming: an experimental and numerical study

Double-sided incremental forming (DSIF) is capable of forming complex three-dimensional components without using component-specific tooling. Forming the components with favourable residual stresses, mechanical properties, and accuracy is still one of the challenging tasks. It is known that the support tool contact condition in DSIF changes the magnitude of residual stresses, thereby allowing the possibility to alter the spring-back and mechanical properties by controlling the support force. In the present work, finite element analysis (FEA) and experimental work are carried out to study the effect of support force (varied from 0 to 500 N) on residual stresses, sheet thinning, and accuracy. A custom-designed tool is used to apply specified force within an acceptable range. In addition, tensile and strain-controlled fatigue tests are also carried out to study the effect of the support force. Results indicate that forming forces predicted using FEA are in good agreement with measured forces. Residual stress measurements and predictions at selected locations indicate that through-thickness residual stress gradients are minimum at a nominal support force (150 N), and improvement in fatigue life is also achieved at the same supporting force.