Development and mechanical properties of three-dimensional flat-knitted fabrics with reinforcement yarns

Three-dimensional (3D) flat-knitted fabrics have become a topic of interest in the field of composites in recent years because of the growing need for rapid preparation of complicated shape preforms. In order to improve the mechanical properties of 3D flat-knitted fabrics, two types of 3D flat-knitted fabrics with reinforcement yarn (FKFR) were developed using ultra-high molecular weight polyethylene (UHMWPE) yarn. Their basic structures were composed of plain structure and interlock structure with tuck stitch, respectively, and the reinforcement yarn was integrated into the fabric as the weft inlay. The tensile, bending, drape, and bursting properties of the two fabrics were characterized. Results showed that the basic structure of the fabric has impacted on the mechanical properties of the fabric significantly. The tensile and bending properties of the fabric with interlock structure were better than that of the fabric with plain structure. During the transverse stretching process, the surface structure of the fabric with interlock structure was more stable. Moreover, transverse yarn strength utilization of the fabric with interlock structure was 1.05, which reached the level of ordinary woven fabric. In addition, the bursting force of the fabric with excellent tensile properties was lower than that of the fabric with a plain structure because the latter has better extensibility.

Experimental investigation on the cross-tensile properties of tubular rivet-reinforced joints

To decrease the exterior protrusion height and improve the tensile strength of the clinched joint, a rivet-reinforcing method was implemented on the clinched joint in this study. Solid rivets and tubular rivets with the wall thickness of 1.0 mm, 1.5 mm, and 2.0 mm were employed to conduct the rivet-reinforcing experiments on the clinched joints. Mechanical interlock structure measurements and mechanical properties tests were performed on the above-mentioned reinforced joints. The results show that the rivet-reinforcing technology can significantly increase the tensile strength and improve the mechanical behavior of the clinched joint. Compared with the NRJ joint (the reinforced joint with no rivet), the static tensile strength of TRJ-1.0 (the rivet-reinforced joint with the tubular rivet of 1 mm wall thickness), TRJ-1.5 (the rivet-reinforced joint with the tubular rivet of 1.5 mm wall thickness), TRJ-2.0 (the rivet-reinforced joint with the tubular rivet of 2 mm wall thickness), and SRJ joint (the rivet-reinforced joint with the solid rivet) is separately increased by 30.05%, 24.59%, 16.28%, and 7.19%. The TRJ-1.0 joint has the highest tensile strength (1489.57 N) among the five types of reinforced joints in the cross-lap-tensile test. The energy absorption capacity of the rivet-reinforced joints decreases as the wall thickness of the tubular rivet increases. Therefore, the TRJ-1.0 joint has the highest energy absorption that is 5.890 J, while the energy absorption of the SRJ joint is the lowest, which is 2.868 J. The TRJ-1.0 joint has the most excellent strength performance in the lightweight evaluation, which with a lightweight evaluation value of [Formula: see text]. However, the TRJ-1.5 joint has the most outstanding energy absorption performance in the aspect of lightweight evaluation, with a lightweight evaluation value of [Formula: see text]. The experiment has proven that the clinched joints reinforced with 1 mm wall thickness tubular rivets have the best mechanical properties.

Dynamic stab resistance of multi-ply three-dimensional warp interlock fabrics with high-performance high-molecular-weight polyethylene yarns for protective applications

Fabrics constructed from 3 D warp interlock fabrics (3DWIFs) structures provide varying flexibility and durability and are promising structures for protective applications. However, its performance toward stab resistance from knife attack should be investigated before applying. In this work, the influences of fabric architectures, ply orientation of stacking sequences, and the number of fabric plies on the dynamic stab resistance are comparatively studied on high-molecular-weight polyethylene (HMWPE) 3DWIFs. It indicates that 3DWIF with orthogonal and through-the-thickness interlock structure reveals a helpful influence on stab resistance. Further investigation on the influence of different ply orientation of stacking sequences, based on the combination of fabrics placed at different angles, is analyzed showing a certain influence of stab resistance. Dynamic stab resistance reveals the linear correlation with a low number of fabric plies (less than 6 plies), but shows a parabolic relationship with the increase of fabric plies (more than 16 plies) until there is no penetration.

Effect of Structural Parameters on the Deformational Behaviors of Multiply 3D Layer-by-Layer Angle-Interlock Para-Aramid Fabric for Fiber-Reinforcement Composite

Materials used in the technical application including composite reinforcements and ballistic fabrics should show not only good mechanical performance but also better deformational behaviors. Meanwhile, three dimensional (3D) warp interlock fabrics have been widely employed in such applications to substitute the two dimensional (2D) fabrics because of their enhanced through-the-thickness performance and excellent formability. The deformational behaviors of such 3D warp interlock fabrics have been also influenced by various internal and external parameters. To understand and fill this gap, the current paper investigates the effects of the warp yarn interchange ratios inside the fabric structure on the formability behaviors of dry 3D warp interlock p-aramid fabrics. Four 3D warp interlock architecture types made with different binding and stuffer warp yarn interchange ratios were designed and manufactured. An adapted hydraulic-driven stamping bench along with hemispherical punch was utilized for better forming behavior analysis such as in-plane shear angle and its recovery, material drawing-in and its recovery, deformational depth recovery, and required stamping forces. Based on the investigation of various formability behaviors, the formability of (3D) warp interlock fabrics were greatly influenced by the binding and stuffer warp yarns interchange ratio inside the 3D warp interlock structure. For example, preform 3D-8W-0S exhibited a maximum deformational height recovery percentage of 5.1%, whereas 3D-4W-8S recorded only 0.72%. Preform 3D-8W-4S and 3D-8W-8S revealed 1.45% and 4.35% recovery percentages toward the deformational height at maximum position. Besides, sample 3D-4S-8W revealed the maximum drawing-in recovery percentage of 43.13% and 46.98% in the machine and cross direction, respectively, around the preform peripheral edges. On the contrary, samples with higher binding warp yarns as 3D-8W-0S show the maximum drawing-in recovery percentages values of 31.21% and 34.99% in the machine and cross directions respectively.

Tensile Properties Analysis Of 3D Flat-Knitted Inlay Fabric Reinforced Composites Using Acoustic Emission

In this work, based on the quasi-static tensile test and acoustic emission technology, the tensile properties of two types of three-dimensional flat-knitted inlay fabrics reinforced composites are investigated, and the acoustic emission characteristic parameters of various damage mechanisms are obtained. The transverse tensile process of specimens could be divided into the elastic stage, yield stage, and fracture stage. We found that, compared with the fluctuation of the stress-strain curve in the yield stage, weft insertion yarns in composite with interlock structure broke almost simultaneously, while the composite with plain stitch broke successively. The transverse and longitudinal tensile strength of the composite with interlock structure was 44.70% and 28.63% higher than the composite with plain structure, respectively. The SEM micrographs showed that the damage mechanism of the composites was matrix fracture, fiber-matrix debonding, and fiber breakage. The amplitude ranges of the three damage mechanisms were 50–65 dB, 65–80 dB, and 90–100 dB, respectively, and the frequency ranges were 35–114 kHz, 116–187 kHz, and 252–281 kHz, respectively. Fiber-matrix debonding and matrix fracture had large cumulative AE energy, numerous events, and long duration time, while fiber breakage had the characteristics of large amplitude, high frequency, low cumulative AE energy, few events, and short duration time.

Research of 3D Woven C/C Composites Bending Properties

Two different kinds of structural preforms were designed and manufactured, which were 3D layer-to-layer angle-interlock structure and 3D solid orthogonal panel structure. C/C composites were made first by chemical vapor infiltration (CVI) and then liquid resin impregnation for complementation. The bending properties of the two 3D woven reinforced C/C composites were tested and analyzed. The inner microstructures were investigated by SEM. The results show that the bending property of 3D solid orthogonal panel preform reinforced C/C composites is higher than that of 3D layer-to-layer angle-interlock preform reinforced C/C composites, and the bending rupture of the former is brittle, the latter is tough.

Design and Weave on Seamless Filter Bag with Three-Dimensional Angle-Interlock Tubular Structure

The advantages of the bag house are expounded in this paper. The some technical parameters of the filter bag are introduced. The weaving plan of three-dimensional angle-interlock tubular fabric is designed. The key points of weave production are explained. Use of angle-interlock tubular structure can weave seamless and thick the filter bag, and improve the filter efficiency of woven fabric. The development of seamless filter bag save sewing process, and improve the production efficiency, and save cost. The seamless filter bag with three-dimensional angle-interlock structure can be widely used to a lot of areas of flue gas filter. It will play a positive role to protect the environment.