Directional trans-planar and different in-plane water transfer properties of composite structured bifacial fabrics modified by a facile three-step plasma treatment

Fabrics with moisture management properties are strongly expected to benefit various potential applications in daily life, industry, medical treatment and protection. Here, a bifacial fabric with dual trans-planar and in-plane liquid moisture management properties was reported. This novel fabric was fabricated to have a knitted structure on one face and a woven structure on the other, contributing to the different in-plane water transfer properties of the fabric. A facile three-step plasma treatment was used to enrich the bifacial fabric with asymmetric wettability and liquid absorbency. The plasma treated bifacial fabric allowed forced water to transfer from the hydrophobic face to hydrophilic face, while it prevented water to spread through the hydrophobic face when water drops were placed on the hydrophilic face. This confirmed one-way water transport capacity of the bifacial fabric. Through the three-step plasma treatment, the fabric surface was coated with a Si-containing thin film. This film contributed to the hydrophobic property, while the physical properties of the fabrics such as stiffness and color were not affected. This novel fabric can potentially be used to design and manufacture functional and smart textiles with tunable moisture transport properties

Effect of meso-scale structures and hyper-viscoelastic mechanics on the nonlinear tensile stability and hysteresis of woven materials

Abstract Woven textiles are not only a craft and industrial product but also a thousand-year-old crystallization of human technology. However, the highly sought after mechanical behavior of fabric, generally undergoing large structural distortion along with material deformation even under small stress, is still not clearly understood despite a growing interest in emerging applications, such as flexible electron devices, biomedicine and other engineering fields. Herein, a numerical methodology was introduced to strengthen the comprehensive understanding of the synergy effect of material mechanics and mesostructures of woven materials. A hyper-viscoelastic constitutive model for yarn materials was proposed, and a meso-scale geometry model captured from a resin-cured woven fabric was used, down to micron-sized weaving structures, to investigate the uniaxial loading and unloading process based on finite element (FE) method. The tensile and hysteresis mechanics was identified based on the validated FE model and parameter study of friction effect and fabric structures. The nonlinear tensile and recovery behaviors were reasonably represented by the developed models and the synergistic effect of inner yarn friction and viscoelasticity on the hysteresis was proved. This study can provide an effective method to analyze and predict the nonlinear tensile and hysteresis behavior of woven fabric, laying down the way to textile-based strain sensing materials by enhancing our design and tuning capabilities of the dimension stability of woven materials under tension.</jats:p

A Hybrid Variational Multiscale Element-Free Galerkin Method for Convection-Diffusion Problems

By coupling the dimension splitting method (DSM) and the variational multiscale element-free Galerkin (VMEFG) method, a hybrid variational multiscale element-free Galerkin (HVMEFG) method is developed for the two-dimensional convection-diffusion problems. In the HVMEFG method, the two-dimensional problem is converted into a battery of one-dimensional problems by the DSM. Combining the non-singular improved interpolating moving least-squares (IIMLS) method, the VMEFG method is used to obtain the discrete equations of the one-dimensional problems on the splitting plane. Then, final discretized equations of the entire convection-diffusion problems are assembled by the IIMLS method. The HVMEFG method has high accuracy and efficiency. Numerical examples show that the HVMEFG method can obtain non-oscillating solutions and has higher efficiency and accuracy than the EFG and VMEFG methods for convection-diffusion problems. </jats:p

An interpolating meshless method for the numerical simulation of the time-fractional diffusion equations with error estimates

Purpose This paper aims to present an interpolating element-free Galerkin (IEFG) method for the numerical study of the time-fractional diffusion equation, and then discuss the stability and convergence of the numerical solutions. Design/methodology/approach In the time-fractional diffusion equation, the time fractional derivatives are approximated by L1 method, and the shape functions are constructed by the interpolating moving least-squares (IMLS) method. The final system equations are obtained by using the Galerkin weak form. Because the shape functions have the interpolating property, the unknowns can be solved by the iterative method after imposing the essential boundary condition directly. Findings Both theoretical and numerical results show that the IEFG method for the time-fractional diffusion equation has high accuracy. The stability of the fully discrete scheme of the method on the time step is stable unconditionally with a high convergence rate. Originality/value This work will provide an interpolating meshless method to study the numerical solutions of the time-fractional diffusion equation using the IEFG method. </jats:sec

Effect of meso-scale structures and hyper-viscoelastic mechanics on the nonlinear tensile stability and hysteresis of woven materials

Woven textiles are not only a craft and industrial product but also a thousand-year-old crystallization of human technology. However, the highly sought after mechanical behavior of fabric, generally undergoing large structural distortion along with material deformation even under small stress, is still not clearly understood despite a growing interest in emerging applications, such as flexible electron devices, biomedicine and other engineering fields. Herein, a numerical methodology was introduced to strengthen the comprehensive understanding of the synergy effect of material mechanics and mesostructures of woven materials. A hyper-viscoelastic constitutive model for yarn materials was proposed, and a meso-scale geometry model captured from a resin-cured woven fabric was used, down to micron-sized weaving structures, to investigate the uniaxial loading and unloading process based on finite element (FE) method. The tensile and hysteresis mechanics was identified based on the validated FE model and parameter study of friction effect and fabric structures. The nonlinear tensile and recovery behaviors were reasonably represented by the developed models and the synergistic effect of inner yarn friction and viscoelasticity on the hysteresis was proved. This study can provide an effective method to analyze and predict the nonlinear tensile and hysteresis behavior of woven fabric, laying down the way to textile-based strain sensing materials by enhancing our design and tuning capabilities of the dimension stability of woven materials under tension

A strain gradient strategy to quantifying longitudinal compression behavior in slender fibrous assembly structures

Slender fibrous assembled structures can easily buckle under longitudinal compressive load. The limitation in characterizing the longitudinal compression behavior poses a significant challenge to the mechanics optimization of such structures. To address this challenge, we use one-dimensional yarns as a model system, and the yarns are deformed in bending to form a strain gradient, from tension to compression, along the radial direction of the yarns. The compression modulus as a function of compression strain is calculated based on bi-moduli elastic theory. The evolution of the fiber arrangement and the position of the neutral layer in the yarn is interpreted along with the change of compression modulus. Also, the local stress distribution in the bent yarn was determined by finite element simulation, and it is remarked that the bending property of yarns is sensitive to the compression modulus. The present study offers insights on the modeling and simulation of fabrics and garments in drape and bending deformation. Results from such investigations can provide effective guidance for the mechanical and structural design of textiles and textile-based composites. </jats:p