Tensile creep of angle-piled boron/epoxy laminates

Tensile creep tests were performed at 75 and 3000F on 26 specimens cut from +- 30-deg and +- 45-deg laminates of boron/epoxy composite material to characterize the creep behavior of these materials. A linear viscoelastic laminate theory proposed by McQuillen was compared with the experimental data for the tests run at 750F. The predicted creep strains differed greatly from the measured values, indicating that the linear theory is not applicable to laminates with these filament orientations. A general creep equation of the form epsilon = k sigma/sup m/t/sup n/ was fitted to the experimental data with excellent correlation. The stress exponents m varied from 1.79 to 5.17 for the four series of tests, thus characterizing the nonlinear behavior of boron/epoxy laminates with these filament orientations. 9 figures, 4 tables