Formation and performance of dimpled steel sheet

摘要

The structural performance of thin-section roll formed products relies on maintaining the maximum stiffness of the section while the optimum economic viability requires a minimisation of the amount of material used. A balance between these conflicting requirements can be achieved through the introduction of bends in the profile to 'stiffen' the section. Further enhancements of the section performance can be obtained by dimpling the material prior to the roll forming operation. (The Ultrasteel~(TM) process patented by Hadley Industries plc). This paper presents an elastic-plastic finite-element simulation of the dimpling process to identify the amount of plastic strain (i.e. a measure of work hardening) introduced and the manner in which this is distributed through the sheet. The additional contribution to plate strength was assessed via three-point bending tests on samples with various degrees of 'dimpling'. The amount of plastic strain induced via the dimpling process can be correlated to the increase in bending strength recorded in the experimental tests.