Volume 7, Issue 6 (November 1979)
A New Load-Transmitting Medium to Measure Strength of Brittle Materials
A testing apparatus based on the principle of a new load-transmitting medium developed by the author is presented in this paper. Instead of solid bearing platens, “Lamina Pack” bearing platens are used in a compression test to overcome the shortcomings of current testing techniques. Data obtained in past investigations of nonmetallic brittle materials demonstrated that machines using solid bearing platens in contact with the specimen cause significant lateral restraint to the specimen and severe disturbances to the specified stress state, resulting in misleading apparent strength measurements. Previous attempts to replace testing machines with solid bearing platens have failed as the machines proposed do not have sufficient load capacity to measure the compressive strength under combined stresses of most of the brittle materials of engineering use. The apparatus exerts no appreciable lateral restraint to the specimen and has a high load-transmitting capacity. Strain measurements on specimens subjected to uniaxial compression applied by lamina platens show uniform deformation and indicate that the specified stress state (purely normal stresses applied to the boundaries of the specimen) has been closely approached.