A model is developed to predict thermal expansion coefficients and elastic moduli of multi-component (hybrid) composites. The model includes the influences of fiber aspect ratio; isotropic and anisotropic fiber materials: planar, threedimensional or arbitrary fiber orientation; hollow and solid spherical reinforcements: and voids. The first step in the procedure is to predict the properties of a n aligned-fiber single-reinforcement composite for each reinforcement type, Various micro-mechanics approaches are used, depending on the type of reinforcement. A simplified version of Lee and Westmann's theory is found to work well for hollow spherical reinforcements. Performing an orientation average accounts for the spatial orientation of each reinforcement, then an aggregate averaging procedure combines the single-reinf orcement properties to model the hybrid. Predictions of the model compare favorably to experimental elastic and thermal properties of short fiber/hollow sphere composites desjgned for very high speed integrated circuit (VHSIC) board applications. 20024.the barrels of PTH.

Cross ply laminates of (02,902)s configuration having AS4 graphite fibers in three epoxy resins of different toughness: 3501-6, Tactix® 556 and Tactix® 695, have been tested to determine their transverse cracking behavior and the associated mechanical response under longitudinal tensile loading. The test data are analyzed using Talreja's con tinuum damage model [1-3]. The material constants needed in the model to predict the in- plane stiffness changes are determined. The measured Poisson's ratio, which shows signifi cant change, is compared with the prediction of the model. The constants for the three materials are found to increase with the increase in their fracture toughness.

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This study is a comparison of independently designed mold flow experiments performed at The Dow Chemical Company with simulations from a computer code developed at The Ohio State University. The experiments used in the validation study included isothermal 1‐dimensional flow with line gating and end venting, isothermal 2‐dimensional flow with converging flow and center venting, and two different resin systems. The simulation results were compared with experimental pressure and temperature readings and fill times. It was found that simulated fill times could be predicted within experimental error and pressure distributions could be predicted with the application of a scaling factor.