Solid-mechanics finite element simulations of the draping of fabrics: a sensitivity analysis
Abstract This paper covers numerical investigations of the draping of woven fabrics into a “hat” shape, combining a hemispherical cup with a wide flat rim. A mechanical approach is adopted using finite element analysis (FEA) methodology. In this, the fabric is considered as a solid sheet with mechanical properties and friction properties. In this study, a linear elastic anisotropic material model describes the deformation of fabrics. An explicit dynamic finite element analysis is applied and systematic parametric numerical studies are presented, which incorporate investigations of the effects of numerical parameters, material properties and processing conditions on the draping of fabrics. More specifically, the effects of the following variables and parameters are included: number of elements, number of time increments in the dynamic FEA analysis, punch speed, shear and tensile moduli of fabric, coefficient of friction for all interfaces and level of load on the fabric holder.
A direct comparison of matched-die versus diaphragm forming
Continuous fibre reinforced thermoplastic laminates, in comparison with monolithic metallic sheets, are effectively inextensible in the direction of their reinforcements and therefore severely limited in the range of possible deformations they can undergo during forming. Inter-ply and intra-ply shearing plays a major role in the determination of the degree of formability of such laminates. The present study focuses on the shear behaviour of CFRT sheets in inter-ply and intra-ply modes aiming to assess their significance in matched-die and double diaphragm forming processes. In order to gain a better understanding of the minimum stress levels necessary to induce the two different shear modes, basic shearing experiments on single plies and unidirectional reinforced laminates were conducted prior to forming spherical shaped dome parts. By forming down-scaled yacht hulls it was intended to apply the findings obtained with the spherical dome parts to other 3-D shapes and to demonstrate the versatility and limitations of both processes.
Networks of Inextensible Cords
This paper will be concerned with the mechanics of idealized textiles consisting of inextensible filaments. The earliest work this writer has found on the subject is due to Tchebycheff and was published only in brief summary in 1878 under the title “Sur la Coupe des Vetements.” This work apparently consisted of a discussion of certain geometrical properties of such idealized textiles.