Precise characterization of nonwoven fabrics such as their transport properties are of paramount importance in development of advanced filtration processes. Currently majority of available knowledge on transport behavior of fibrous materials is based on macro-scale empirically researched phenomena. Thus, evaluation of transport behavior of nonwovens based on fundamental scientific principles at micro-scale still remains a challenge that has to be tackled by scientists. In this paper, an integrated approach employing high-resolution X-ray micro-computed tomography and finite volume method are presented to predict permeability of needled nonwoven fabrics. In order to achieve the objectives of this research, dimensionless permeability of needled nonwoven fabrics with various porosities was computed using CFD tools. Comparisons of simulated results with experimentally obtained data and the published empirical and analytical models were made. Considering solid volume fraction of the samples, acceptable agreement between the results and previously published findings was observed. It was also established that experimental samples ideally can be represented as a three-dimensional random structure.

The aggregate gradation is one of the most important parameters in the mechanical properties of hot mix asphalt (HMA). Thus, determining the aggregate gradation is a very significant subject in civil engineering. Usually, to estimate the aggregate gradation, it is required to separate the aggregate from the bitumen, and this operation can be time-consuming and even dangerous related to chemical solvents. Moreover, several computer-based methods have been established to model the internal structure of HMA in two- and three-dimensional methods and can be applied to determine the aggregate gradation, but these methods need special and expensive equipment. Therefore, in this study, a simple approach is introduced to quickly and easily determine the aggregate gradation of HMA from the prepared cross-section images of cylindrical samples using numerical and image-processing techniques such as fitting equation and colour space system. The obtained results indicate that the introduced method can detect the aggregate gradation with high accuracy and can be used as a satisfactory alternative to other expensive methods.

Behavior of woven fabrics during complex deformations is most influentially affected by their shear behavior. Shear characteristics of woven fabrics can be explained by fabric shear rigidity and shear hysteresis. In this study, the effects of weft density, weft count, and fiber type on shear behavior of woven fabrics in the principal directions of fabric were statistically evaluated. Statistical methods such as multiple linear regression analysis, univariate test, and correlation analysis were also applied. The univariate test results confirmed that the weft density is the most dominant parameter that affects fabric shear properties. Multiple linear regression results point to poor shear behavior in woven fabrics with cotton weft yarns. In addition, correlation between the shear rigidity of the fabrics along principal directions with the Milasius fabric firmness factor and the fabric cover factor as integrated structural parameters was established. High correlation was found to exist among Milasius fabric firmness factor, fabric cover factor, and shear rigidity of fabrics along principal directions.

This paper aims to investigate the effects of fiber hybridization technique on the mechanical behaviors of non-absorbable braided composite sutures. Fifteen types of hybrid braided sutures (HBSs) made of polyester (PET), polypropylene (PP), and polyamide 6 (PA6) are produced and tested to measure ultimate tensile strength (UTS), maximum strain, elastic modulus, and breaking toughness. Based on the results, it is observed that the suture material plays a significant role in the tensile and mechanical performance of HBSs, and they can be tailored through the different combinations of yarns according to the required mechanical properties. Experiments exhibit occurrence positive hybrid effect in both maximum strain and elastic modulus, and negative hybrid effect in UTS. The optimal tensile performance is associated with the hybrid structure comprising 75% PA6-12.5% PET-12.5% PP. This means the ternary structure with higher PA6 content along with PP and PET, demonstrates a synergistic effect. Thus, such a ternary composite structure is very promising for the design of novel non-absorbable sutures. Due to the absence of similar results in the specialized literature, this paper is likely to advance the state-of-the-art composite non-absorbable sutures and contribute to a better understanding of the hybridization concept for optimizing composite material systems.

Braided composites are gaining attention in the most industrial applications. To design rods with optimal tensile properties against combined loads, experimental studies were conducted to investigate the effect of using axial yarn and core in different categories on the tensile properties of braided reinforced composite rods. In this study, six types of braided composite rods with different arrangements of braid components (axial yarn or core type) were produced using glass and polyester fibers with epoxy resin as the matrix. The elastic modulus, ultimate tensile strength, and work of fracture of these rods were tested, and the experimental elastic modulus of samples were compared with previously developed models. Moreover, comparing the stress-strain results of the samples revealed that the produced hybrid samples demonstrate pseudo-ductile tensile behavior, showing varying trends as the type of reinforcement is altered. The results indicate that using a double-layer triaxial braid as reinforcement for the composite can increase the elastic modulus up to 13% compared to the similar single-layer sample. Additionally, employing a double-layer triaxial braid as reinforcement for the composite leads to a greater work of fracture. However, in terms of ultimate tensile strength, biaxial braid reinforcement demonstrates better performance in reinforcing the composite rods.