Assuring life in composite systems

A computational simulation method is presented to assure life in composite systems by using dynamic buckling of smart composite shells as an example. The combined use of composite mechanics, fi nite element computer codes, and probabilistic analysis enable the effective assessment of the dynamic buckling load of smart composite shells. A universal plot is generated to estimate the dynamic buckling load of composite shells at various load rates and probabilities. The shell structure is also evaluated with smart fi bers embedded in the plies right below the outer plies. The results show that, on the average, the use of smart fi bers improved the shell buckling resistance by about 10 % at different probabilities and delayed the buckling occurrence time. The probabilistic sensitivities results indicate that uncertainties in the fi ber volume ratio and ply thickness have major effects on the buckling load. The uncertainties in the electric fi eld strength and smart material volume fraction have moderate effects and thereby in the assured life of the shell.