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Automobile body panels made from advanced high strength steel (AHSS) provide high strength-to-mass ratio and thus AHSS are important for automotive light-weighting strategy. However, in order to increase their use, the significant wear damage that AHSS sheets cause to the trim dies should be reduced. The wear of dies has undesirable consequences including deterioration of trimmed parts' edges. In this research, die wear measurement techniques that consisted of white-light optical interferometry methods supported by large depth-of-field optical microscopy were developed. 1.4 mm-thick DP980-type AHSS sheets were trimmed using dies made from AISI D2 steel. A clearance of 10% of the thickness of the sheets was maintained between the upper and lower dies. The wear of the upper and lower dies was evaluated and material abrasion and chipping were identified as the main damage features at the trim edges.

In this study, a procedure for characterizing advanced high strength steel sheets is presented in view of determining the material parameters for constitutive models that can be used for accurate prediction of springback and sidewall curl. The mechanical properties of DP980 and TRIP780 sheets were obtained experimentally, and their cyclic tension-compression behaviour was modeled with the Chaboche nonlinear kinematic hardening model and the Yoshida-Uemori two-surface plasticity model that are implemented in LS-DYNA. The unloading moduli were determined from monotonic tension tests at various prestrain levels. An inverse approach based on linear and quadratic response surfaces created by Sequential Strategy with Domain Reduction (SRSM) methodology using LS-OPT software was used and investigated to identify specific material parameters in each constitutive model.

Experimental and numerical studies have been completed on the deformation behaviour of round AA6061-T6 aluminum extrusions during an axial cutting deformation mode employing both curved and straight deflectors to control the bending deformation of petalled side walls. Round extrusions of length 200 mm with a nominal wall thickness of 3.175 mm and an external diameter of 50.8 mm were considered. A heat treated 4140 steel alloy cutter and deflectors, both straight and curved, were designed and manufactured for the testing considered. The four blades of the cutter had an approximate average thickness of 1.00 mm which were designed to penetrate through the round AA6061-T6 extrusions. Experimental observations illustrated high crush force efficiencies of 0.82 for the extrusions which experienced the cutting deformation mode with the deflectors. Total energy absorption during the cutting process was approximately 5.48 kJ.

The inhomogeneous distribution of surface asperities generated by deformation induces variability in the friction and initiates strain localizations during metal forming. The friction literature generally does not account for the strong influence localized variations in material properties have on the friction behavior. A prototype apparatus was developed that measures the friction behavior under simulated forming conditions and enables detailed characterization of the influences of the microstructure and the topographical conditions that occur under those conditions. The results demonstrate that the measurement system can resolve subtle real-time changes in the dynamic friction coefficient, and that a correlation could exist between the largest surface asperities and the largest variations in the measured friction coefficient.

The forming limit diagram of sheet materials has been used as an effective quality assurance tool in the stamping industry for almost forty years. Empirical relations have been established to predict the position of the Forming Limit Curve (FLC) in strain space for many grades of automotive sheet steel. Nevertheless, experimental FLC determination continues to be required not only for new materials (new generation high strength steels, aluminum alloys, etc.) but also to evaluate manufacturing processes where a prestrain is applied prior to the final forming operation. A variety of testing methods has been used to determine limiting strains in sheet metal samples for a range of forming modes. Also, various techniques have been developed to determine the onset of necking in the formed samples. The purpose of this paper is to present the details of a visual method for determining the occurrence of incipient necking.

This paper investigates the application of standard formability testing results for aluminum alloy tailor welded blanks (TWB) to full size stampings. The limit strains obtained from formability testing are compared to measured strains in a larger scale part. The measured strains in the full scale part are also compared to predictions from finite element simulation.

The behaviour of sheet metal flowing through a drawbead is of significant interest to engineers in the stamping industry. Indeed, the drawbead configuration determines not only the forces that restrain the metal as it flows into the die but also affects how the material workhardens prior to the forming process. The purpose of this work was to experimentally determine in-situ bending radii in a strip while it is pulled through a drawbead. This was achieved by mounting a camera onto the binder of a single-action channel draw die near the end of a drawbead insert. Fiber optic cables were used to direct light in the closed die onto the edge of the sheet. Images of the sheet edge were recorded as it flowed through the drawbead, then post-processed in order to analyze the strip profile and determine the minimum bend radii. Maximum bending strains were also calculated from the measured radii.