FINITE ELEMENT SIMULATION OF FORCES IN STRIPS TYING METAL SHEET COILS

摘要

Long metal sheets are commonly wound several turns around cylindrical rolls by winding processes to become sheet coils for compactness and easy handling purposes. The present paper proposes idealized boundary conditions to be applied on inner and outer edges of sheet coils for analyzing forces in strips tying them, using finite element method. The assumed initial condition is a multi-ply metal sheet coil with all plies overlapping each other's without contact pressure when inner and outer edges of coil are subjected to self equilibrium forces and bending moments which would create, from a flat sheet, the same radii of curvature at these edges. The final state is thus simulated by releasing these forces and bending moments. Explicit formulas for forces and bending moments at inner and outer edges are developed and presented for elastic perfectly plastic material assumption. The coil is meshed into 8-node curve-shell elements; the interaction between adjacent plies is accounted for by surface-to-surface contact and target elements and the strips are represented by 3D-beam elements; Coulomb's friction contact and large displacement schemes are used. Experiments are conducted with a galvanized steel sheet manually wound and tied by two stainless steel strips. Finite element simulation gives good agreements with experimental measurements for tension forces in strips and radial detachment from contact state at some locations.