EVALUATION OF THE IITRI COMPRESSION TEST METHOD FOR STIFFNESS AND STRENGTH DETERMINATION

The objective of this paper is to evaluate the IITRI Compression Test Method for measuring the axial compressive modulus and strength of composite materials possessing a high degree of anisotropy in the axial direction. The influence of material anisotropy and test specimen geometry on the data reduction scheme used to characterize the axial compressive modulus and ultimate strength is examined. The findings demonstrate that ASTM D3410 specimen geometries, recommended for the IITRI and Celanese compression test methods, may not always be appropriate for materials that are highly anisotropic in nature. The significance of the findings on appropriate specimen design for thick section laminates is also discussed. An error investigation is included which demonstrates to what extent the experimentally determined compressive modulus may be affected if careful consideration of the specimen geometry is not made. Additional aspects of the subject are discussed.