Morphology mechanism of thin-walled cylinder with circumferential ribs by local shear forming based on the interaction between chip formation and matrix deformation: a combined experiment and modeling study

Local shear forming (LSF) is a promising method for manufacturing thin-walled cylinders with circumferential ribs (TWCCR) by actively utilizing “chip” formation and matrix deformation. However, the final morphology is highly complex and sensitive to forming parameters due to the interaction between chip formation and matrix deformation, posing a significant challenge for precision control. This study systematically deciphers this interaction and its governing role. Experimental results identify two distinct morphologies: a non-uniform high rib with thinning cylinder and a uniform low rib with thickening cylinder. The transition of morphologies is determined by a critical feed ratio, which increases with relative shear depth. Crucially, the underlying interaction is elucidated by analyzing the deformation states of chip-matrix system. The simulation results prove that the interaction exerts a net hindrance effect on chip formation, which increases the minimum shear depth, controls the movement of the material diversion point, and reduces the shear angle. Furthermore, a novel index termed excessive shear depth is proposed, which effectively differentiates the morphologies and provides a direct criterion for process design.