Material Behavior of an Ultra-High-Performance Concrete Forming Die for Sheet Metal Hydroforming

New sheet metal forming technique and low cost forming die development has resulted from economic requirements and an increasing number of part variants. To form detailed and uniform sheet metal contours in the range of elastic material behavior of the die material, these dies have to withstand approximate pressures of 100 MPa (14.50 ksi) for sheet metal hydroforming. A promising approach to cost-efficient die production is ultra high performance concrete (UHPC) use, particularly for high pressure sheet metal hydroforming. Uniaxial and triaxial compressive stress state stress-strain behavior was investigated through experimentation at various ages for a fine grained UHPC. Three concrete cylinder confinements were additionally tested to achieve a multiaxial stress state. After fabrication of a forming tool prototype, its performance was analyzed in applying a fluid pressure up to 90 MPa (13.05 ksi). The formed sheet shape accuracy and ultimate prototype load were examined. There was also determination of the friction coefficient between sheet metal and concrete. Forming tests have demonstrated that the investigated UHPC can be successfully used as sheet metal hydroforming die material.