Fiber Stresses in a Cracked Monolayer: Comparison of Shear-Lag and 3-D Finite Element Predictions*

Shear-lag and 3-D finite element predictions for the fiber stresses in a cracked monolayer are compared. Results are given for 5-fiber wide boron/aluminum and Kevlar 49/epoxy monolayers containing a single broken fiber. Both methods of analysis are found to predict nearly the same fiber stress distribution along the crack- tip fiber when the monolayer is fully elastic. Results for highly loaded monolayers with extensive matrix yielding are not in quite as good agreement, but even then the predicted stress distributions are within 5%. These calculations show that a shear-lag analysis is accurate even when 1) the matrix is relatively stiff and can carry substantial loads (e.g., boron/aluminum), and 2) the fiber is highly anisotropic, (e.g., Kevlar 49/epoxy).