EXPERIMENTAL ASSESSMENTS ON THE STRAIN CONCENTRATION AROUND SMALL HOLES IN PMMA

Abstract

A series of tensile tests of polymethyl methacrylate (PMMA) open-hole specimens with holes of various diameters was carried out. Digital image correlation (DIC) analysis for the strain field distribution around the holes is performed. It is found that the evaluated strain concentration around relatively large holes (with diameter of several millimeters) is in good agreement with the classical elasticity solution; however, it tends to reduce in the samples containing smaller holes. Around the holes of diameter less than 500 <i>&mu;</i>m, maximum values of strain (hoop strain) are found to be 1.5-2 times lower than the classical elasticity solution, with extrapolated tendency to decrease down to unit value of strain concentration around the micro/nano-sized holes. Statistical analysis of the deviations between experimental and theoretical data is performed and discussed together with assessments on the accuracy of the obtained DIC results.