A new extraction method of creep exponents and coefficients from an indentation creep test by multiaxial stress analysis

摘要

In this paper, we propose a method for analytically extracting creep exponents and coefficients in Norton's law from the results of a ball indentation creep test using the finite element method. Elastic-creep finite element analyses were performed with the creep exponent and coefficient varied widely, and a simple method of obtaining three principal stresses at a point of the tested material in the vicinity of an indenter ball tip was developed. Using the three principal stresses in combination with a creep constitutive equation, we propose an analytical method to derive creep exponents and coefficients. This method is verified to determine the two material constants in Norton's law with a satisfactory accuracy via finite element analyses. The indentation creep tests were performed using Sn-37Pb solder to demonstrate the validity of the proposed method in experiments. The proposed method successfully extracted the creep exponent and coefficient of the solder in experiments.