The intention of this study is to find the 'safe' long term behavior of elasto-plastic materials, reinforced (dilutely) with unidirectional stiff fibers. The composite is subjected to fluctuating load which acts (primarily) transverse to the fibers. The aim is to predict what would be the highest allowable stress amplitude that the composite can endure ('the endurance limit') when undergoing 'infinite' number of cyclic loading. To reach this goal we employ (a) Melan's static shakedown theorem for formulating the lower bound to the endurance limit, and (b) Koiter's kinematic shakedown theorem for formulating its upper bound. Both theorems are adjusted to capture an isotropic elasto-plastic metal matrix with an embedded non-interactive fibers (i.e. a dilute composite). The fibers/matrix bonding quality is included in a parametric form ranging from no slip condition (m=1) to free-to -rotate condition (m=0). The solution for the bounds becomes rigorous as the volume fraction of well bonded fibers approaches zero (representing a single fiber in an infinite matrix).
展开▼
