A Numerical Analysis of Fracture in a Laminated Fibrous Composite Plate.
AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OHIO SCHOOL OF ENGINEERING
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A crack in a laminated, composite plate was modelled using numerical methods. The experimental results used to validate this analysis were for a 0, or - 45,90 graphiteepoxy plate with a center notch oriented normal to the loading direction. Two, Two-dimensional finite element models were used to determine the size of the crack tip damage zones. One involved a purely elastic analysis, and in the other, the element ply stiffness was completely discounted if the stresses exceeded the Tsai-Hill failure criterion. Damage zone diagrams showing the growth and shape of the ply damage zones at increasing load levels were developed for both models. The size of the subcracks in each ply were linearly related to the opening mode stress intensity factor, K sub I, and to the strain energy release rate, G. A critical stress intensity factor approach, an instability approach, and a new fracture load prediction method based on load versus load bearing area diagrams were used to predict the fracture load. Since this new method provided close upper and lower bounds on the fracture load and is applicable to complicated structures, it was considered the best of the three methods. Author
- Laminates and Composite Materials