Indentation of elastically soft and plastically compressible solids

• Published in: Acta mechanica Sinica Vol. 31; no. 4; pp. 473 - 480
• Main Authors: Needleman, A., Tvergaard, V., Van der Giessen, E.
• Format: Journal Article
• Language: English
• Published: Beijing The Chinese Society of Theoretical and Applied Mechanics; Institute of Mechanics, Chinese Academy of Sciences 01.08.2015
• Subjects: Classical and Continuum Physics; Computational Intelligence; Engineering; Engineering Fluid Dynamics; Research Paper; Theoretical and Applied Mechanics; 压痕硬度; 固体; 塑性压缩; 屈服强度; 弹粘塑性; 杨氏模量; 粘塑性本构关系; 软弹性; Compressibility; Finite element analysis; Indentation; Plasticity
• ISSN: 0567-7718; 1614-3116
• DOI: 10.1007/s10409-015-0467-9

The effect of soft elasticity, i.e., a relatively small value of the ratio of Young＇s modulus to yield strength and plastic compressibility on the indentation of isotropically hardening elastic-viscoplastic solids is investigated. Calcu- lations are carried out for indentation of a perfectly sticking rigid sharp indenter into a cylinder modeling indentation of a half space. The material is characterized by a finite strain elastic-viscoplastic constitutive relation that allows for plas- tic as well as elastic compressibility. Both soft elasticity and plastic compressibility significantly reduce the ratio of nomi- nal indentation hardness to yield strength. A linear relation is found between the nominal indentation hardness and the log- arithm of the ratio of Young＇s modulus to yield strength, but with a different coefficient than reported in previous studies. The nominal indentation hardness decreases rapidly for small deviations from plastic incompressibility and then decreases rather slowly for values of the plastic Poisson＇s ratio less than 0.25. For both soft elasticity and plastic compressibility, the main reason for the lower values of indentation hardness is related to the reduction in the hydrostatic stress level in the material below the indenter.