Thermal buckling of thin sheet related to cold rolling: Latent flatness defects modeling

In cold rolling of thin sheet metal, the interstand tension has a role to mitigate the wrinkling of the plate due to residual stress. When this mechanical loading is reduced up to full unloading, it can induce or increase elastic wave buckling, leading to latent flatness defects. An experimental work is proposed to study the relation between residual stresses, global tensile stresses and buckling for wavy edge flatness defects during the mechanical unloading. Residual stresses are generated by thermal loading. The wrinkling shape and thermal field are measured by optical full-field measurements. Finite Element simulation using a combination of a non-linear algorithm and a bifurcation analysis that take into account mid-surface imperfections can follow the wrinkling behavior.