QUANTITATIVE MEASUREMENTS OF YOUNGS MODULUS USING THE MINIATURIZED DISK-BEND TEST

The miniaturized disk-bend test (MDBT) has been used to evaluate the yield stress and fracture toughness of thin disk-shaped samples 3 mm in diameter. Two experimental configurations may be employed: loading applied by a solid ball (ball-on-ring mode) or by a hollow cylinder (ring-on-ring mode). Literature values of the yield stress of ordered intermetallic compounds and the fracture toughness of several ceramics have been successfully reproduced by the MDBT technique. In this paper, we show how the ring-on-ring mode can be used to measure Young's moduli for hot-pressed NiAl samples of varying porosity and thickness in the range 200 mu m less than or equal to t less than or equal to 600 mu m. The key to this method lies in the derivation of an equation allowing the determination of Young's modulus from the measured load-displacement curves even for thicknesses where a state of plane stress may not necessarily exist.