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.
Formability of textile preforms for composite applications. Part 2: Evaluation experiments and modelling
Abstract Formability is an important parameter in assessing the processability of fibrous preforms in various composite applications. A new approach is proposed in which selected characterization measurements are used to evaluate the forming behaviour of preform fabrics. In the first part of this study, experiments characterizing the deformation behaviour of textile preforms were carried out. These tests included in-plane tension, transverse compression, in-plane shear and out-of-plane bending. In this part of the study, in order to investigate the behaviour of the preform fabrics in a forming process, formability experiments using a designed geometry were performed with the selected textile preforms. Forming energy was chosen as the index to reflect the difficulty level in a forming process. The correlation between the results of the characterization tests and those of the formability experiments was analysed, and the dominant process parameters determined. It is shown that the proposed characterization tests can be used to evaluate effectively the textile fabric preform formability, which is crucial to the forming process of composite applications.
Evaluation of buckling load and dynamic performance of steel shear wall retrofitted with strips made of shape memory alloy
One of the most imperfections of the steel shear wall is out of plane displacements that cause severe damage in both structural and non-structural elements. In this paper, the effects of shape-memory alloys on steel shear walls are investigated. First, a numerical analysis using the finite element method in ABAQUS software has been carried out according to an experimental test. The results of the numerical analysis have been verified with experimental results. Next, shape-memory alloy fibers have been added vertically and horizontally to various parts of the steel shear wall. The results show that retrofitting with the shape-memory alloy reduces the out-of-plane displacement of the steel shear wall under both cyclic and seismic loadings. Besides, the buckling load in the steel shear wall increases when it is retrofitted with the shape-memory alloy. Also, the total out-of-plane movement (accumulated absolute displacements) of the steel shear wall and non-structural damage are controlled by the characteristic of a shape-memory alloy material called “super-elastic”.