Improved correlation for elastic modulus prediction of metallic materials in the Small Punch Test

Abstract

Generally, the correlation factors of parameters obtained from the load-displacement curve of small punch tests and the mechanical properties of materials are only acceptable for the materials tested in each investigation. Although the standardization of the correlation factors for different groups of materials is the objective in much of the research on the Small Punch Test (SPT), there are not many studies focused on the physical sense of these correlation factors. Consequently, the applicability of these factors needs the prior knowledge of the material to be tested with comparisons between SPT's and standardized tensile tests.This investigation, through finite element modeling and a theoretical analysis, goes in depth into the understanding of the first zone of the SPT curve and the study of an unloading/loading cycle introduced into this zone in order to obtain an improved correlation factor for the elastic modulus. This factor is acceptable for most isotropic and homogeneous metallic alloys and depends only on the geometrical setup of the test. Experimental tests (tensile tests and SPT's) were added to these numerical/theoretical analyses to demonstrate the suitability of this correlation.