1346 ISSN 1229-9197 (print version) ISSN 1875-0052 (electronic version) Fibers and Polymers 2017, Vol.18, No.7, 1346-1352 Experimental Study on Compressive, Flexural and Fatigue Behavior of Warp-knitted Spacer Fabrics Reinforced Polyurethane Cast Elastomer Composites Masih Yousefpour, Mohammad Saleh Ahmadi*, and Pedram Payvandy Department of Textile Engineering, Yazd University, Yazd 89195-741, Iran (Received January 27, 2017; Revised May 5, 2017; Accepted May 8, 2017) Abstract: This paper reports an experimental study on compressive, flexural and fatigue behavior of polyurethane cast elastomers (PCE) reinforced with warp-knitted spacer fabrics (WKSF). It aims to investigate new applications for these fabrics as the reinforcements for elastomeric parts such as shoe soles, rubber floor coverings, vibration dampening and shock absorbing pads, etc. A series of polyester WKSF with different thickness, structure of outer layer fabric and spacer yarns density was prepared and converted to PCE reinforced WKSF using the hand molding method. All the samples, including the neat PCE, were subjected to static compression, flat and spherical compression, three-point bending and flexural fatigue tests. The results showed that reinforcing PCE with WKSF, considerably enhances its spherical compressive strength (concentrated loading), flexural strength and fatigue resistance. However, it deteriorates flat compressive strength (distributed loading) and recovery behavior after static compression loading. The effect of fiber weight fraction, thickness, structure of outer layer fabric and spacer yarns density on the mentioned properties of the composites was discussed in the paper. Keywords: Elastomer composites, Warp-knitted spacer fabrics, Fatigue, Bending, Compression Introduction Spacer fabrics as a category of three-dimensional fabrics, comprise of two outer fabric layers connected with pile yarns, known as spacer yarns. Spacer fabrics can be produced by weaving, weft knitting and warp knitting processes. However, warp knitting is the most commonly used technique owing to its high speed production and high product versatility. Warp-knitted spacer fabrics (WKSF) are knitted on double needle bar Raschel machines. WKSF have already been used for several industrial applications, such as automotive, sports, leisure, safety and protection [1-5]. Due to their unique structure, they have good moisture transmission rate [6], excellent resilience properties, energy absorption and high air permeability [7]. Various physical, mechanical and hydraulic properties of raw WKSF have been studied in the literature [8-15]. However, WKSF can also be used as the reinforcement for 3D composite materials, such as sandwich structures. Velosa et al. [16] Studied mechanical behaviors of 3D warp-knitted fabrics reinforced unsaturated polyester composites. They discussed the effect of some factors, such as spacer thread density, yarn fineness and structure of outer fabrics, as well as thickness of fabrics, on the mechanical behavior of the composites. Abounaim et al . [17-20] investigated the properties of thermoplastic composites reinforced with flat WKSF. The results show that the mechanical properties of these composites are dependent upon the arrangement and integration of reinforcing yarns. Biaxial inlays were found to give the optimum results. Han et al. [21-23], systemically studied the quasi-static mechanical and deformation behaviors of cement powder impregnated WKSF. The results show that WKSF improve both compressive and tensile behavior of the composites. Lu et al. [24] reported the compressive behavior of warp-knitted spacer fabrics (WKSF) impregnated with shear thickening fluid (STF) when subjected to quasi- static compression and low-velocity impact loadings. They concluded that The compressive behavior of the STF impregnated WKSF has a significant strain rate effect and it shows higher energy absorption and a lower peak load than those of the WKSF under the same impact loadings. Recently, a few efforts have been made to study the mechanical properties of WKSF reinforced flexible foam composites [25-29]. In general, the results indicate that the WKSF/foam composites show higher mechanical properties compared to neat syntactic foam. Moreover, it is found that the fabric structural parameters such as the surface layer structure, inclination-angle of spacer yarns and the volume fraction and type of micro balloons have significant effects on the flexural, compression and impact behavior of the WKSF/foam composites. This work aims to investigate the properties of WKSF reinforced polyurethane cast elastomer composites under compressive, flexural and fatigue loadings. It is going to seek new applications for the WKSF as the reinforcement for elastomeric parts such as shoe soles, rubber floor coverings, vibration dampening and shock absorbing pads, etc. The effects of the structural parameters of WKSF (surface layer structure, density of spacer yarns and the fabric thickness) on the mechanical performance of the composites is discussed in this study. Moreover, the effect of loading type (concentrated or distributed) in compression is investigated. *Corresponding author: ms.ahmadi@yazd.ac.ir DOI 10.1007/s12221-017-7085-z