Flow properties of flexible fibers are poorly understood compared to those of rigid particles. In this study, a Schulze ring shear tester is used to measure the flow properties of fibers made of cut fishing wire and cut rubber cord, which have different levels of flexibility. For a comprehensive study, the discrete element method is employed to simulate flexible fiber flows. The simulations are validated by comparing with the experimental measurements. Studies show that an increase in fiber bending modulus leads to a reduction in the deformation and solid volume fraction, but it has no effect on the shear stress with the same normal stress. An increase in fiber-fiber friction coefficient, below a critical value of 0.8, can augment the angle of internal friction. The contact stiffness, contact damping coefficient, and bond damping coefficient only have limited impact on the shear flow behavior in the ranges considered.

No abstract

No abstract

No abstract

The breakage of an agglomerate of wet flexible fibers impacting a plane is computationally investigated in this work using the discrete element method. In the agglomerate, the fibers stick together due to cohesive liquid bridge forces. Agglomerate breakage with various impact conditions, initial configurations, fiber properties, and liquid bridge properties is systematically investigated. The degree of breakage is governed by the impact energy, the cohesion energy due to liquid bridges, the energy dissipation/absorption through fiber-fiber contacts and fiber deformation, and the efficiency of force transmission within the agglomerate. More specifically, breakage is promoted by increasing impact velocity, decreasing agglomerate size, increasing initial compaction, increasing fiber bending modulus, decreasing liquid surface tension, and decreasing liquid-to-solid volume ratio. Breakage is strongly dependent on the modified Weber number, that is, the ratio of the Weber number to a dimensionless rupture distance, which is a measure of the impact energy relative to the cohesion energy. K E Y W O R D Sagglomerate breakage, discrete element method, flexible fiber, liquid bridge force