Interactions and orientation in concentrated suspensions of rigid rods: Theory and experiment

[摘要] A theory for the processing-induced fiber orientation and stress in fiber reinforced-polymer composites is presented. Short-fiber-reinforced polymer composites are represented by concentrated suspensions of rigid rods. In concentrated suspensions, fiber-fiber contact is likely and affects the fiber orientation state and suspension rheology. Fiber orientation is given as a function of the strain in the continuum and the probable effects of physical inter-fiber contact. Continuum stress is calculated from the stress in the fluid and fibers, where fiber stress is a result of the local disturbance in the fluid velocity field and of the inter-fiber contact forces. Fiber orientation is described via probability density function whose transport equation has the form of a generalized advection-diffusion equation with a orientation dependent diffusion. This equation is solved using a finite difference scheme and the results are presented versus experiments with suspensions with planar orientation in planar stretching flow. Experiments and simulation agree that increasing concentrations result in increased interaction-based diffusion.

[关键词] Engineering, Mechanical