SIZE EFFECT ANALYSIS ON STRAIN SOFTENING OF QUASI-BRITTLE MATERIALS CONSIDERING STRAIN GRADIENT EFFECT
准脆性材料试件应变软化尺度效应理论研究

The effect of length due to shear localization is studied. Based on non-local theory consideringinteraction among microstructures,non-local plastic shear strain is obtained,and dependent on local plastic shear strain and its second spatial gradient. For simplicity,shear band is treated as one-dimensional problem and theclosed-form solution on plastic shear strain in shear band is obtained. Then,an analytical relation between axial average strain (or displacement) and axial compressive stress is obtained,which exhibits size effect. The relation becomes steep as length is increased and class II behavior can occur as length is large. Besides,the relation also becomes steep as inclination angle of shear band increases. The presented theoretical results are compared with a few existing experimental results and the agreement is good.