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April 26th, 2008

Multiscale Modeling of Composite Materials

Abstract:
Understanding the deformation or thermal behavior of composites has always been a complex problem. One must take into consideration the behavior of the reinforcement (particle, fiber, or whisker), matrix, and, of course, the interface or interphase formed between these components. Clearly, the interplay between the components in a composite is also key. Load transfer from the matrix to the fiber is directly related to the aspect ratio of the fiber, as well as the yield stress of the matrix (or, in brittle composites, the shear strength of the interface). With the advent of new computational methodologies and techniques, not to mention the sheer increase in efficiency and speed of computer processors, multiscale modeling has become an important part of understanding the behavior of composite materials. Multiscale modeling is particularly suited toward composites because of the multiple length scales involved as well as the overall complex nature of composite behavior. The three papers in this section illustrate the importance of multiscale modeling of composites. A variety of numerical computational techniques are used, such as finite-element modeling, crystal plasticity, and atomistic modeling, to understand the behavior of the composite, More importantly, two or more of these techniques are used in combination to stitch together the behavior at different length scales. The paper by A. Misra et al. discusses the deformation behavior of nanoscale metallic multilayered composites. Metallic composites with layers at the nanoscale exhibit very high strengths. The mechanical behavior of these composites was studied in terms of the atomic structure at the interfaces between the layers. The atomic level modeling is particularly needed here because the layer thickness is in the range of a few nanometers. Information obtained from the atomistic modeling, such as the critical stress required for dislocations to overcome the barrier at the interface and be transmitted to adjacent layers, are used in dislocation dynamics simulations to study dislocation-dislocation interactions. The third level of modeling involves crystal plasticity modeling of phenomena on the length scale of a grain and encompasses information from atomistic and dislocation dynamics simulations.

Source:
redorbit.com

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