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Elasticity and Fracture of Composite Materials

Stephen A. Langer, ACMD
W. Craig Carter, Edwin Fuller, and Andrew R. Roosen, Materials Science and Engineering Laboratory

Composite materials with complicated microstructures (such as ceramics) are important in many industrial applications. Previous analysis and computer simulations of their properties have been based on idealized simplifications of the microstructure. The goal of this project is to construct a finite-element computer model from a digitized image of a real microstructure (see Figure 7), numerically distort the model, and identify the features of the microstructure responsible for the elastic and fracture properties of the material. The simulation uses object-oriented C++ in order to handle a wide variety of material grain types and a wide variety of computational elements. For example, the material could be a composite of grains with differing elastic moduli, differing degrees of elastic anisotropy, or differing fracture thresholds. It could contain voids or liquid regions. The computational elements could represent portions of single intact grains, fractured grains, or could be composite elements containing boundaries where two or more grains meet. The simulation takes advantage of state-of-the-art sparse matrix methods and is being designed with future parallel implementations in mind. Currently, the general extensible framework for elastic calculations is complete.

Figure 7:  A digitized micrograph of showing complicated grain structure.