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Cite this document
A test apparatus and method developed to obtain high strain rate compressive mechanical properties of various fiber-reinforced composite materials is described. This direct compressive method uses a drop tower to impart a load at dynamic rates to the test fixture. Uniform specimen loading is accomplished through the use of aligned guiderails to constrain all but the vertical motion of a free-sliding impactor. Specimen endcaps, specific to thick-section testing, are implemented to prevent premature brooming failure. A piezoelectric transducer and aluminum absorbers are some of the refinements introduced to allow acquisition of stress and strain data free of distortion. Strain rates on the order of 8 s-1 have been achieved, and higher rates appear possible. Material property data were obtained on a series of AS4 graphite/PEEK thermoplastic [02/90]8s composite laminates. The results of this first study indicate that at high strain rate loading, the strength of this material increases 42% over static values, while the strain to failure increases by 257#x0025;. There also appears to be a small effect of increased strain rate on the initial and secant moduli for this material.
composites, high strain rate, compressive properties, fiber-reinforced composites, loading
engineering manager, Forensic Technologies International, Annapolis, MD
Materials engineer, Composites and Resins Branch of the David Taylor Research Center, Annapolis, MD