Multiscale Modeling of Three-Dimensional Random Fiber Structures using a Random Walk Approach
Assimina Pelegri (Rutgers University ), Stephen Recchia (Rutgers University)
Prager Medal Symposium in honor of George Weng: Micromechanics, Composites and Multifunctional Materials
Wed 10:45 - 12:15
MacMillan 117
Accurate acquisition of representative geometry for finite element analysis at various scales can be challenging. Added complications arise when the geometry is representing a manufactured or biological composite. In this work we reproduce crystalline micro-fibril stacking of Kevlar to form a single fibril joined by a non-ordered crystal structure. The single fibril can either have ellipsoidal or rectangular micro-fibrils stacked in rectangular or ellipsoidal architecture to form a fibril. The advantages of this approach include the ability to grow a fibrous structure along a path using a Random Walk methodology. Since the directionality of the fibers is random but always stepping from one side of the path towards the other, the fibers can wind around each other and tangle or terminate if needed. The resultant geometry produced by the model can be used to represent anything from axons found in white matter to almost aligned Kevlar molecular chains in the micro-fibril crystal without recompiling any of the base model. Moreover, a rotation matrix operation can be added to the path of the fibers facilitating a linear or sinusoidal path directionality around the three local coordinates. The resultant geometry produced can be representative of the tortuous path white matter axons undergo. Furthermore, rotation about the path axis allows for the twisted geometry of carbon nano-tube yarn, Kevlar yarn, or metal cable to be replicated. Another advantage is the ability to add spherical objects to the path of the fibers simulating fiber growth around an obstacle, as seen in biological systems. The object can be on the order of 1 fiber diameter to almost the same size as the path. This technique can represent white matter axons flowing around an ogliodenrocyte or impurities at the fibril level to yarn level of Kevlar manufacturing. In due course, the single fibril architecture can hierarchically transcend into larger scales forming fibers and composite structures.