EVALUATION OF CUBIC SPECIMENS FOR COMPRESSION TESTING AT DIFFERENT STRAIN RATES

摘要

Cubic test specimens fabricated using Newport NCT321/G150 carbon unitape prepreg have been tested under uniaxial compression. Three different methods based on - specimen surface strain measurement, strains based on actuator displacement, and relative displacement of loading platens, have been evaluated for determination of the material stiffness from the test. A finite element model was used to study the different factors affecting the strain measurement in a cubic specimen under compression loading. The experiments reveal that the use of surface strains results in least error in computation of modulus, which is further supported by the finite element analysis. The analysis also indicates that the stress distribution in specimens tend to be more uniform when the ratio of the platen to specimen modulus is about 10 or higher.