Prediction of Trimmed Edge Stretching Performance PIs: Brad Kinsey and Yannis Korkolis, UNH Jyhwen Wang, TAMU

4. Prediction of Trimmed Edge Stretching Performance Industrial Need and Relevance: Failure strains in the stretch bending fracture and edge cracking can be significantly lower than predicted using classic methods such as the forming limit curve. The goal of the project is to understand the mechanism of edge stretching failure and create a Edge Stretching Limit (ESL), in particular with respect to pre-strained materials. NSF I/UCRC Planning Meeting

4. Prediction of Trimmed Edge Stretching Performance Project Objectives: Determine and validate the ESL, Establish a methodology to predict the trimmed edge performance of pre-strained sheets, and Identify key material properties, tooling geometries, and process factors affecting the ESL. Korkolis, NUMISHEET, 2016 NSF I/UCRC Planning Meeting

4. Prediction of Trimmed Edge Stretching Performance Punch displ.: 18 mm (onset of 1st rupture) Approach/Methodologies: Perform hole expansion tests, including Digital Image Correlation, with various edge conditions created. Machined Sheared Etc. Assess the effect of material, e.g., plastic behavior, grain size distribution, phase constituents, etc. on ELS. RD NSF I/UCRC Planning Meeting

4. Prediction of Trimmed Edge Stretching Performance Approach/Methodologies: Pre-strain sheets using the custom machine available at UNH. Conduct numerical simulations to assess the stresses in the ESL failure. NSF I/UCRC Planning Meeting

4. Prediction of Trimmed Edge Stretching Performance 2 cameras for 3D DIC punch (260 kN cap.) DIC Lamp Die Set blankholder Deliverables: ESL for various process parameters, e.g., material variables, tooling geometries, and process factors Pre-strained ESL Accurate material data based on conditions at the hole Numerical simulation model NSF I/UCRC Planning Meeting

4. Prediction of Trimmed Edge Stretching Performance Budget and Timeline: Estimated cost of the project is $400k for two years. Task / Milestone Year 1 Year 2 Year 3 Q1 Q2 Q3 Q4 ESL parameter testing   Pre-strain material  Pre-strained ESL  Material characterization  Numerical model NSF I/UCRC Planning Meeting

4. Prediction of Trimmed Edge Stretching Performance Discussion: Are the industrial need and relevance accurately captured? Are the objectives realistic and complete? Are the approaches technically sound and appropriate? Are there alternative implementation paths or better approaches? Are the deliverables impactful to industrial partners? Are the budget and timeline reasonable? Are there conflicts with intellectual property or trade secrets? List additional project specific questions are appropriate. NSF I/UCRC Planning Meeting