1. Accuracy of Fully Elastic vs. Elastic-Plastic Finite Element Analysis Masters of Engineering Rensselear Polytechnic Institute By Nicholas Szwaja May 17, 2012

2. Introduction Purpose: Analyze the accuracy of Finite Element Analysis (FEA) when it is used to compare fully elastic and elastic-plastic deformation in high strength steel Method: Use FEA to model a tensile test using a standard specimen. –Apply tensile load using fully elastic and elastic-plastic material properties

3. Fully Elastic Linear relationship governed by Hookes Law: σ = Eε –where: σ = Stress E = Modulus of Elasticity ε = Strain Provided by memry.com

4. Elastic Plastic Plastic deformation is defined as permanent change in shape or size of a solid body without fracture –Occurs after yield point –Non-linear –FEA requires manual input of yield stress and strains from existing tests/calculated data

5. Expected Outcome Fully Elastic –Accurate stress/strain curve up to the yield point in FEA. Stress/Strain will continue to act linearly through plastic region –Hand calculation will validate linear relationship for uniaxial stress Elastic-Plastic –Accurate stress/strain curve up to the fracture point in FEA. Stress/strain will be linear up to the yield point then non-linear from the yield point to fracture. –Hand calculations will provide significant challenge and some percentage of error could exist. Hand calculations will have to consider arbitrary assumptions. i.e no stress/strain in y or z direction (only axial)

6. Work Accomplished Fully Elastic FEA Model successfully built and analyzed

7. Work Still Required Analyze model with elastic-plastic input –Develop stress/strain curve for elastic-plastic model Develop hand calculations for fully elastic and elastic plastic to validate FEA models Verify FEA is accurate Initial draft of the report