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.
Experimental study on bond behavior between high-strength grout and deformed steel bars
Abstract Engineers use high-strength grout to connect precast concrete members for its low shrinkage and good fluidity. This paper designed 87 central pull-out specimens using the control variable method to investigate the influence of factors on the rebar-grout bond property such as compressive strength, steel grade, bar diameter, transverse stirrups, and bond length. The test result showed that improving grout compressive strength (85.8 MPa–122.7 MPa) cannot improve the bond strength, which was different from the previous conclusions of concrete pull-out tests. Simplified formulas were presented for calculating the characteristic values of bond strength, residual strength, peak slip, and relative slip of load-holding platform based on parameter analysis. Then, a constitutive model was proposed to predict the full-range bond stress-slip curve of high-strength grout and steel bar specimens from bearing to failure. Finally, FEA models were established to evaluate the applicability and accuracy of the constitutive model.