Determination of material intrinsic length and strain gradient hardening in microbending process

Microbending experiments of pure aluminum show that the springback angles increase with the decrease of foil thickness, which indicates obvious size effects and attributes to plastic strain gradient hardening. Then a constitutive model, taking into accounts both plastic strain and plastic strain gra...

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Bibliographic Details
Published in:International journal of solids and structures 2011-01, Vol.48 (1), p.163-174
Main Authors: Hezong, Li, Xianghuai, Dong, Qian, Wang, Yu, Shen, Diehl, A., Hagenah, H., Engel, U., Merklein, M.
Format: Article
Language:English
Subjects:
Applied sciences
Constitutive relationships
Exact sciences and technology
Foils
Forming
Fundamental areas of phenomenology (including applications)
Gradient of effective plastic strain
Hardening
Inelasticity (thermoplasticity, viscoplasticity...)
Material intrinsic length
Mathematical models
Metals. Metallurgy
Microbending
Microorganisms
Other forming methods
Physics
Plastic deformation
Plastic strain
Production techniques
Solid mechanics
Springback
Static elasticity (thermoelasticity...)
Strain
Structural and continuum mechanics
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Summary:Microbending experiments of pure aluminum show that the springback angles increase with the decrease of foil thickness, which indicates obvious size effects and attributes to plastic strain gradient hardening. Then a constitutive model, taking into accounts both plastic strain and plastic strain gradient hardening, is proposed to analyze the microbending process of thin foil. The model is based on the relationship between shear yield stress and dislocation density, in which the material intrinsic length is related to material properties and average grain numbers along the characteristic scale direction of part. It is adopted in analytical model to calculate the non-dimensional bending moment and predict the springback angle after microbending. It is confirmed that the predictions by the proposed hardening model agree well with the experimental data, while those predicted by the classical plasticity model cannot capture such size effects. The contribution of plastic strain gradient increases with the decrease of foil thickness and is independent on the bending angle.
ISSN:0020-7683
1879-2146
DOI:10.1016/j.ijsolstr.2010.09.016