Tabbed Versus Untabbed Fiber-Reinforced Composite Compression Specimens

摘要

The development of suitable specimen configurations and loading methods for the compression testing of high strength composite materials has received considerable attention during the past decade, and especially during the past five years. Both experimental and analytical investigations of very specific aspects of specimen and test fixture configurations have been performed. Many seemingly conflicting results have been presented, leading to considerable confusion within the composite materials testing community. However, a definite conclusion appears to now be emerging, viz., the use of tabs on compression test specimens has a detrimental influence on measured strength. This has been qualitatively suspected for some time since analytical studies and detailed finite element analyses consistently predict induced stress concentrations at the tab ends of the specimen gage section. Numerous approaches have been followed to minimize these stress concentrations, of course including the total elimination of tabs. Key analytical and experimental results, taken from the extensive published literature as well as from the author's own recent work, are presented and compared, to demonstrate the consistent trends that actually do exist in the seemingly scattered and confusing published literature. Finally, options currently available for the successful compression testing of high strength composite materials are presented.