A Segmented Cylinder Test for Determining Hoop Stress in Composite Structures

Abstract

The usefulness of a cylinder test for obtaining hoop strength design data for glass fiber composite structures is well recognized. The advantage, theoretically, is primarily in the “statistical” value of fiber strength if uniform loading can be achieved. Both the split-dee and pressurized ring testing methods are limited in this regard; in addition, in the latter schemes it is impossible to test helical windings for structural evaluation. The history of the Allegany Ballistics Laboratory (ABL) cylinder testing program is briefly reviewed. The development of a mechanical segmented cylinder test method, which provides for uniform radial expansion, is reported. Included are fundamental biaxial performance data on hoop geometries for various glass fiber — resin systems. Presented, also, is the analysis of the test fixture mechanics with confirmative experimental data. The test method and fabrication of test specimens are outlined.