Research Information System
Image-Based Simulation for Industry 2021 (IBSim-4i 2021), London, England, 18 - 21 October 2021, pp.1, (Summary Text)
Nonwoven materials are used in different sectors such as health care, agriculture, automotive, civil engineering, etc. Understanding and characterization of mechanical behavior of nonwovens are challenging due to their complex microstructure composed of polymer-based randomly orientated fibers bonded together using various manufacturing methods such as, thermal, mechanical, or chemical processes. To analyze these complex structures, it is important to implement proper mathematical concepts, which govern the geometrical representations of these random fibrous structures. A fiber crimp angle (angle between two tangent lines of two shoulders of a crimp in its maximum slope) [3] is one of the main geometrical parameters that can be used to analyze such structures to evaluate nonwovens analytically and numerically. Finite-element simulations are performed to examine the real-life performances of nonwovens [1-2], and the contribution of crimp angle of fibers is crucial for numerical results, especially in modelling and simulations fibers. Moreover, sealing and filtration properties of nonwoven materials are examined using CFD analysis, and the crimp angle of each fiber is a critical factor, which affects the permeability of a fibrous network. Many theoretical studies were conducted to describe the fiber crimp angle in nonwovens, but only in 2D, considering a Machine Direction and a Cross Direction [3]. However, the 2D crimp angle does not consider the fiber crimp in a Thickness Direction which is important for high-density nonwovens. This study focuses on a representation of a 3D fiber crimp angle of nonwoven fabrics using mathematical models by determining the initial and final orientation of fibers between bond points. Each fiber paths are tracked to identify the orientation angle in 3D environment to compute the fiber crimp angle in all three directions. Initially, a virtual fiber domain is modelled using straight and crimped fibers based on mathematical expressions. New parametric algorithms are developed to define fiber orientations in a 3D space. Once the algorithms are verified, they are extended to measure the parameters of real nonwovens. An X-ray micro-CT system is used to acquire the 3D volumetric image of a nonwoven sample and process it with the system's software to denoise the image for a better visualization. Various voxel-processing techniques are deployed to enhance the image quality and compute 3D crimp angles of nonwovens.