Effect of Assembly Anomalies on the Strain Response of Composites in the Sphere Joint Region of the DARPA Man-Rated Demonstration Article.

摘要

The compressive response of thick, quasi-isotropic, AS4/3501-6 laminates with geometric anomalies were investigated theoretically and experimentally. The specimens considered were rectilinear with nominal dimensions of 10 inches long, by 4 inches wide, by 0. 78 inches thick. The anomalies were designed to simulate expected fit-up clearance conditions resulting from normal manufacturing tolerances in the sphere joint regions of the DARPA Man Rated Demonstration Article. Tests were conducted both with unfilled fit-up gaps and with fit-up gaps filled with a polymer shimming material (Hysol EA9394). Strains were monitored in the specimen gage sections and in regions of high strain concentration resulting from the manufacturing anomalies. Measured strains correlated well with predicted strains from an ABAQUS Finite Element Analysis. For all test cases the specimens were able to withstand strains due to the anomalies when gage section strain reached 7000 microstrain. One specimen with no anomalies was tested to failure in uniaxial compression and failed in the gage section at 89,000 psi and 13,500 microstrain, which is equivalent to thin-section composite failure strains.