Experimental and numerical true strain assessment on sheet forming for different tool design

The forming tests are being developed with the purpose of enabling forming companies to better understand the sheets formability. The identification of the regions where tension-tension, tension-compression, and/or plane strain occurred during the forming process can aid the process planning through the tools geometry optimization. This work consisted of evaluating, experimental and numerically, the major true strain obtained with different punch designs, which were used in addition to the traditional Nakazima test tool. The main objective was to study the true strain profile as an alternative method to analyze the tool design influence on stretching forming of high stampability steels (DC 06). The friction coefficient was investigated, and an evaluation was also made of the chosen program's response quality (validation). The results are given as a major true strain distribution profile at points distributed linearly from the region close to the die radius to the punch pole. The result expectation is to help the process planning and the material evaluation based on the correct tool design specification in order to obtain the desired true strain distribution in the formed part.

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