Lizhi Sun Civil and Environmental Engineering The University of Iowa

1. Effective Elastoplastic Model of Particle ReinforcedMetal Matrix Composites with Interfacial Debonding Lizhi Sun Civil and Environmental Engineering The University of Iowa J. Woody Ju Civil and Environmental Engineering University of California, Los Angeles Presented at ASCE 14th Engineering Mechanics Conference EM2000 -- Austin, Texas May 21-24, 2000

2. Problem Statement Before Deformation After Deformation

3. Presentation Outline • Introduction • Interfacial Debonding Treatment • Micromechanics of Three-Phase Composites • Homogenization -- Effective Yield Function • Constitutive Relation • Damage Evolution • Conclusions

4. Introduction • Jasiuk and Tong (1989), Pagano and Tandon (1990), Qu (1993), Sangani and Mo (1997), Wu et al. (1999) • Voyiadjis and Park (1997) • Yuan et al. (1997), Lissenden (1999), Haddadi and Teodosiu (1999), Li and Ellyin (2000) • Zhao and Weng (1996), Wong and Ait-Kadi (1997) • Ju and Lee (2000)

5. Interfacial Debonding • Assumption:Partially Debonded Isotropic Particles=Perfect Orthotropic Particles where

6. Interfacial Debonding • Matrix Expression: • Rules:

7. Homogenization -- Effective Yield Function • Matrix (von Mises Yield Criterion) • Ensemble-Average • Effective Yield Function

8. Homogenization -- Effective Yield Function Collection from perfect particles Collection from debonded particles

9. Homogenization -- Effective Yield Function • Local Stress Calculation Elastic Mismatch Tensor: (Interior-Point) Eshelby’s Tensor: Exterior-Point Eshelby’s Tensor:

10. Effective Elastoplastic Constitutive Relation • Elastic: • Plastic:

11. Damage Evolution • Two-Parameter Weibull Distribution

12. Conclusions • Effective Elastoplastic Model of Aligned Particle Reinforced Metal matrix Composites Considering Progressive Interfacial Debonding • Random Microstructure • Multiaxial Loading Condition • No Effective Constants Needed