The Use of a Small Punch Test Procedure to Determine Mechanical Properties

Abstract

A small ball-punch-on-rectangular-specimen design was developed to test materials such that cracking occurs along a desired orientation. Energy to fracture is determined from the punch load and displacement, which are measured continuously during the test. A three dimensional ¼ finite element model was formulated to simulate the punch test. The calculated load-displacement and stress-strain curves compared reasonably well with the experimental results. The plastic strain distribution was consistent with the observed location of fracture, and the reduction in thickness was also in agreement with measurements taken from deformed test specimens. Room temperature and 250 °C tests were performed on a SA106 grade B steel for two orientations, C-L and L-C. Empirically, the punch test's energy to break results showed a correlation with fullsize JIc results. The test method can also be used to determine the Ductile-to-Brittle-Transition-Temperature (DBTT) behavior of steel. An ASTM A533, grade B material was tested to -180 °C and the typical DBTT behavior, relative to Charpy test results, was observed. Although the technique described in this paper shows some correlations with JIc and the DBTT, the scatter is larger than results for full-size specimens.

CHARACTERIZATION OF FRACTURE IN Fe3Al-BASED ALLOY USING THE SMALL PUNCH TEST

“…The information following from the figure is the same as concluded by Bulloch [21]. It is clear that the trends predicted by Lee et al [25], eq. 7, best reflected the fracture toughness across the whole region of strains.…”

“…Similar linear relations were subsequently also reported in refs. [23][24][25][26]: Suzuki [24] Lee [25] Geary [26] Application of these equations to present experimental data is illustrated in Fig. 10.…”

“…• The equation of Lee et al [25] represents the best tool for evaluation of fracture toughness from the small punch data.…”

Factors Affecting the Mechanical Properties of Compact Bone and Miniature Specimen Test Techniques: A Review

“…Similarly Geary and Dutton [35] used small punch test on 3 mm diameter discs of structural steels and relationships were developed to obtain tensile properties, fracture toughness etc. Lee et al [49] developed a small punch test using rectangular specimens to determine the fracture energy.…”

Key issues involved with the use of miniature specimens in the characterization of the mechanical behavior of polymeric biomaterials—A review

“…The first comprises studies of fundamental issues, examples being: the effect of variation in the relative size of the indenter, receiver hole, and specimen thickness on the results from miniaturized disc bend tests24; and the relationship between values of properties obtained from tests that use various types of MTSs, such as tensile, disk bulge, and microhardness tests 26. In the second group, the finite‐element analysis method has been used for the computation of the following parameters/features of MTSs: the strain energy density at the crack initiation point and, hence, the fracture toughness;19 force‐displacement curves;15, 25 and the von Mises stress, equivalent plastic strains, and vertical deflections of the upper and lower surfaces of a disc, as a function of radial position 25. In the third group of efforts, a number of innovative techniques have been used in the experiments.…”