This paper is concerned with a theoretical and experimental verification of a micromechanical model of newly developed sandwich panels denoted as 3D integrated woven sandwich composite panels. The integrated hollow core was made of a pile of 3D bars with a special configuration. Integrated woven sandwich composite panels consist of two fabric faces which were interwoven by pile fibers and therefore a very high skin core debonding resistance was obtained. With the objective of qualifying the mechanical properties of these structures, fairly extensive experimental research was carried out by investigators. Although some numerical methods have been developed to predict the mechanical behaviors of these structures, there are less analytical models in this area. Due to the computational difficulties and the time consuming nature of the finite element method, in the present study, a new micromechanics analytical model has been suggested for predicting the compressive strength of integrated woven sandwich composites. In order to evaluate the proposed model, fabricated samples with different pile heights and pile distribution densities were subjected to flatwise compression tests. The results show that compressive properties of integrated woven sandwich composite

This paper is concerned with the effect of core pile yarn hybridization on the lowvelocity impact response of 3D integrated-woven sandwich composite panels. For this purpose, at first, hybrid yarn was produced by a co-wrapped technique that is composed of polyester and glass fibres as shell and core structure, respectively. Then, 3D-woven samples with glass and hybrid pile yarns were fabricated, and after the impregnation, the behaviour of fabricated samples under low-velocity impact was experimentally investigated. In order to characterize this new type of hybrid structure, the fabricated samples with different pile heights and pile distribution densities were subjected to low-velocity impact tests at an energy level of 8 J. The impact

This research describes the structural and tensile properties of glass/polyester hybrid yarns produced by co-wrapped and side-by-side technologies. Based on co-wrapping technology, the hybrid yarn is composed of polyester and glass fibers as shell and core structure, respectively. In order to produce this type of yarn, a new machine was designed and manufactured to investigate the influence of linear densities (16, 50.67, and 67.11 tex) and wrapping densities (115, 180, and 230 turns/m) of polyester fibers. It was found that the linear and wrapping densities have a significant effect on the structural and tensile properties of the final hybrid yarn. In order to compare, another type of hybrid yarn was also been investigated by hybridization of glass and polyester fibers (16, 50.67, and 67.11 tex) via side-by-side method. In comparison with the side-by-side and single glass yarns, the co-wrapped yarns have higher breaking load and tenacity due to the lateral compression force of the wrapped filament. The results show a 62% increase in breaking load of co-wrapped hybrid yarns in comparison with the side-by-side and single glass yarns.

This paper describes an experimental study of the impact of yarn structure on the thermal properties of worsted fabric. In this study, four different spun yarn structures (Solo, Siro, and single ply and two ply Ring) were woven into four fabric structures (Plain, Twill2/1, Twill2/2 and Basket2/2) and their thermal properties were studied. In addition, the thermal behavior of finished and unfinished samples was also evaluated. Results showed that the finishing process causes an increase in thermal conductivity and warmth to weight factor and a decrease in thermal insulation. Different spinning systems, also affect the thermal properties of the worsted fabrics. Samples with Siro yarns in the weft were found to have the highest thermal conductivity and those made from single ply weft yarn the lowest thermal conductivity. A relation between fabric thermal insulation and air permeability and thickness was also found.

In this article, an experimental study is conducted to compare eight improvement methods for the tensile strength of textile-reinforced mortars (TRM). 12 series of samples with different modification methods are compared to determine the most effective factors on crack initiation force and tensile strength of TRM. Eight modification methods are categorized under three main groups of mortar modification, fabric modification, and fabric-mortar interface modification. TRM's first crack force and ultimate force are considered as indices of method performance. One-way ANOVA and factorial analysis were also conducted to statically determine the most significant methods for improving TRM tensile behavior. The results showed that the modification of mortar by short fiber is the most effective method for the enhancement of TRM's first crack force. Also, the methods which led to the transfer of failure mode from mortar to fabrics were the most effective methods on TRM ultimate force improvement. The result showed that coating fabrics with epoxy affects TRM tensile strength more than all other methods. Extra enhancement of TRM ultimate force is achieved by adding silica fume to epoxy before coating the fabrics and spreading the sand and short fibers on impregnated fabrics.