Quantification and analysis of coating surface strains in T-bend tests

Abstract Pre-painted sheet metal (e.g. coil coated with polyester-melamine) undergoes large deformations when formed into architectural cladding or white goods. The coatings provide protection and superior aesthetics, so must withstand failure by cracking delamination during forming. T-bend test is an industry standard used to qualitatively compare the formability of mimics conditions experienced hemming processes. forming strain governed, understanding surface strains in great interest manufacturers. For first time, maximum have been predicted using finite element modelling (FEM) verified experimentally digital image correlation. experimental shapes deformed blank are compared FEM results for further verification. In addition, a novel analytical model proposed determine strains. It shown that up ~ 225% applied 0T (bent around zero thickness spacer) reducing 23% at 4T four times spacer). model, data new show excellent agreement indicate behaviour independent substrate material used. Understanding quantifies formerly qualitative T-bend. This will improve efficacy test, allowing formers coating developers better understand performance requirements, reduce waste develop coatings. Graphical abstract