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Springback Control of Ultra-High StrengthSteel Sheet PartsPIs: Yannis Korkolis and Brad Kinsey, UNHJyhwen Wang, TAMUJian Cao, Northwestern
1. Springback Control of Ultra-High Strength Steel Sheet PartsExecutive Summary: Objective/Industrial Need: control springback in UHSS ( 1 GPa) Approach: use varying punch stroke trajectories for improvement Deliverable: effective forming method and FEA simulations Budget and Timeline: 400k for 2 years; supports two RAs Comments: close collaboration with OEMs for trial part design,material suppliers, and servo press manufacturer for experimentsNSF I/UCRC Planning MeetingSlide 2
1. Springback Control of Ultra-High Strength Steel Sheet PartsIndustrial Need and Relevance: For lightweighting purposes, the use of UHSS isdesirable ( 1 GPa). However, excessive springback, limited ductility,and tool life concerns are problematic. Thus,methods to form UHSS are required, focusingfirst on springback. Modeling required for virtual predictions,validation, and physical understanding of effects.NSF I/UCRC Planning MeetingSlide 3
1. Springback Control of Ultra-High Strength Steel Sheet PartsProject Objectives:1. Implement forming process on a servopress to allow flexibility with respect tothe variable ram motion/control;2. Simulate and validate process; and3. Control springback of UHSS sheet toallow more structural stampingapplications.NSF I/UCRC Planning MeetingServo-press at PostechSlide 4
1. Springback Control of Ultra-High Strength Steel Sheet PartsApproach/Methodologies: Investigate punch stroke trajectories, e.g., stepwise mode, usinga servo-press that can improve formability of UHSS. Past research has shown potential but need on 1 GPa materialNSF I/UCRC Planning MeetingBarlat et al., 2015, IJMFSlide 5
1. Springback Control of Ultra-High Strength Steel Sheet Parts350Higher Binder Force(HBF)Approach/Methodologies: Past research has shownimprovements for a stepped binderforce trajectory, determined using aneural network (NN) based on initialpunch force trajectory. Springback angle controlledbetween 10 – 12 using NN.Binder Force (kN)300250200150Lower Binder Force (LBF)10050001020PD % 304050Punch Displacment (mm)input layer (i)hidden layer (j)h0x0Wj0 xi hjWj1WjiWjNy1h1x1xNoutput layer (k)hJ W1jW2j ykWkj WKjyKVishwanathan, Kinsey,and Cao, 2003, JMSENSF I/UCRC Planning Meetingy2Slide 6
1. Springback Control of Ultra-High Strength Steel Sheet PartsApproach/Methodologies: The proposed scaled test article(s) is acombination of a B-pillar and shotgun. Perform numerical simulations,including punch stroke trajectories, forvalidation of the process and physicalunderstanding.NSF I/UCRC Planning MeetingMetal Forming Magazine, March 2016Slide 7
1. Springback Control of Ultra-High Strength Steel Sheet PartsApproach/Methodologies: Results from past servopress researchIncreased drawing depthElimination of fractureVarious punch stroke trajectoriesNSF I/UCRC Planning MeetingElimination of wrinklingOsakada et al, CIRP review paper, 2011Slide 8
1. Springback Control of Ultra-High Strength Steel Sheet PartsDeliverables: Test component for furtherassessment Servo-press punch stroketrajectories for controlledspringback Numerical simulation models for improvedunderstanding of physical phenomena Criteria and empirical guidelinesNSF I/UCRC Planning MeetingBarlat et al., 2016, MMTASlide 9
1. Springback Control of Ultra-High Strength Steel Sheet PartsBudget and Timeline:Estimated cost of the project is 400k for two years.2 RAs will work on the project (1 experimental and 1 FEA)Task / MilestoneYear 1Q1 Q2 Q3 Q4 Q1Year 2Q2Q3Q4Tooling design/productionImplementation of processConduct experimentsMaterial characterizationNumerical modelNSF I/UCRC Planning MeetingSlide 10
1. Springback Control of Ultra-High Strength Steel Sheet PartsDiscussion:– 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?NSF I/UCRC Planning MeetingSlide 11
Control springback of UHSS sheet to allow more structural stamping applications. NSF I/UCRC Planning Meeting Slide 4 . Metal Forming Magazine, March 2016. 1. Springback Control of Ultra-High Strength Steel Sheet Parts . Criteria and empirical guidelines Barlat et al., 2016, MMTA. 1. Springback Control of Ultra-High Strength Steel Sheet Parts
