The Experts below are selected from a list of 3492 Experts worldwide ranked by ideXlab platform
Zhenku Lei - One of the best experts on this subject based on the ideXlab platform.
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shear deformation and energy absorption analysis of flexible fabric in yarn Pullout Test
Composites Part A-applied Science and Manufacturing, 2020Co-Authors: Zhenku Lei, Yang Feng, Jianchao Zou, Da LiuAbstract:Abstract The friction level between yarns significantly affects the ballistic performance of flexible fabrics. In this study, single yarn Pullout Tests of Kevlar 49 plain weave fabric under different preloads and different yarn Pullout rates were carried out. The in-plane shear deformation of the fabric was measured using a digital image correlation method to determine the global shear strain and shear modulus. In addition, based on the stick-slip phenomenon in the process of yarn pulling, a bilinear stress transfer model between yarns was developed. The energy absorption mechanism and interface shear stiffness were theoretically analyzed, and the yarn interface parameters were inversely obtained from the experimental data. The analytical results of the proposed stress transfer model are consistent with the experimental load-displacement curve.
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energy analysis of fabric impregnated by shear thickening fluid in yarn Pullout Test
Composites Part B-engineering, 2019Co-Authors: Zhenku Lei, Yang Feng, Che LiuAbstract:Abstract Impregnating fabrics with shear thickening fluid (STF) to form bi-phase composite is a potential method to improve the bulletproof resistance of flexible fabrics. In this study, a planetary ball milling method was used to prepare STF with 62, 65 and 70 wt% mass fraction using silica (SiO2) as dispersing phase and ethylene glycol as dispersant. The Kevlar 49 plain woven fabric was impregnated to form bi-phase composite. The yarn pull-out Tests of neat fabrics and STF impregnated fabrics with loading speeds of 100, 500 and 1000 mm/min were carried out respectively. The experimental results show that STF impregnated fabrics have higher yarn pull-out loads than neat fabrics, and show a correlation of yarn Pullout speed. A new energy absorption model is proposed to analyze the energy absorption mechanism in yarn Pullout Test. It is concluded that the work done by external force in yarn pull-out Test can be equivalent to the energy dissipation of friction between yarns. The friction energy dissipation of STF impregnated fabrics is obviously increased compared with that of neat fabrics.
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experimental study on yarn Pullout Test of stf modified fabric
IOP Conference Series: Materials Science and Engineering, 2018Co-Authors: Yang Feng, Zhenku Lei, Saisai Cao, Qingchao Fang, Shouhu XuaAbstract:Shear thickening fluid (STF) solution with SiO2 as dispersing phase and ethylene glycol as dispersing medium was prepared by ball milling, Kevlar49 plain woven fabrics impregnated with SFT were prepared. The impact resistance and shear deformation of the STF modified fabrics were studied by single-yarn pull-out Tests and digital image correlation (DIC). The experimental results show that a dynamic slippage of yarns makes the STF attached to the yarn surface appear shear thickening effect, so the sliding friction between the yarn is higher than the static friction due to the increased viscosity. Therefore, the bigger pull-out force of the STF-fabrics increases the energy absorption capacity of the fabrics. The DIC results show that the maximum shearing angle and the residual shearing angle of the STF modified fabrics are larger than those of the pure fabrics, indicating that the STF will increase the friction between the yarns without affecting the fabric flexibility.
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study on single yarn Pullout Test of ballistic resistant fabric under different preloads
Microelectronics Systems Education, 2017Co-Authors: Q C Fang, Zhenku LeiAbstract:During bullet penetrating fabric, the pull-out force of yarn in fabric is related to the impact resistance of fabric when the yarn is pulled out from the fabric. The complex uncrimping and friction slip behavior occur during the yarn Pullout process, which is critical to learn the impact resistance of fabric. Based on digital image correlation technique, the deformation behavior of Kevlar 49 fabric subjected to preload during the single-yarn Pullout process was studied in this paper. The Pullout force and displacement curve shows a straight rise and an oscillated decrease. In the linear rise stage, the yarn uncrimping causes a static friction effect. The maximum of the Pullout force is not linearly increased with the preload. In the oscillating descending stage, the local descent of the Pullout force indicates that the yarn end is gradually withdrawn from the fabric, and the local rise indicates that the yarn end moves to the next weft/warp interaction until the yarn is completely pulled out. The shear deformation of fabric corresponds to the single-yarn Pullout process.
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stress transfer of a kevlar 49 fiber Pullout Test studied by micro raman spectroscopy
Applied Spectroscopy, 2013Co-Authors: Zhenku Lei, Qua Wang, Wei QiuAbstract:The interfacial stress transfer behavior of a Kevlar 49 aramid fiber-epoxy matrix was studied with fiber Pullout Tests, the fibers of which were stretched by a homemade microloading device. Raman spectra on the embedded fiber were recorded by micro-Raman spectroscopy, under different strain levels. Then, the fiber axial stress was obtained by the relationship between the stress and Raman shift of the aramid fiber. Experimental results revealed that the fiber axial stress increased significantly with the load. The shear stress concentration occurred at the fiber entry to the epoxy resin. Thus, interfacial friction stages exist in the debonded fiber segment, and the interfacial friction shear stress is constant within one stage. The experimental results are consistent with the theoretical model predictions.
Shuhsie Chu - One of the best experts on this subject based on the ideXlab platform.
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effect of silica fume on steel fiber bond characteristics in reactive powder concrete
Cement and Concrete Research, 2004Co-Authors: Yinwe Cha, Shuhsie ChuAbstract:Abstract In this paper, the effect of silica fume on the bond characteristics of steel fiber in matrix of reactive powder concrete (RPC), including bond strength, Pullout energy, etc., are presented. The experimental results on steel fiber Pullout Test of different conditions are reported. Various silica fume contents ranging from 0% to 40% are used in the mix proportions. Fiber Pullout Tests are conducted to measure the bond characteristics of steel fiber from RPC matrix. It is found that the incorporation of silica fume can effectively enhance the fiber–matrix interfacial properties, especially in fiber Pullout energy. It is also concluded that in terms of the bond characteristics, the optimal silica fume content is between 20% and 30%, given the conditions of the experimental program. The microstructural observation confirms the findings on the interfacial-toughening mechanism drawn from the fiber Pullout Test results.
Brian Zornig - One of the best experts on this subject based on the ideXlab platform.
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effect of matrix strength on Pullout behavior of steel fiber reinforced very high strength concrete composites
Construction and Building Materials, 2011Co-Authors: Taher Abulebdeh, Sameer Hamoush, William F Heard, Brian ZornigAbstract:Abstract This paper presents the results of single-fiber Pullout Tests for deformed and smooth steel fibers embedded in the newly developed very-high strength concrete (VHSC) matrixes. The Pullout Test program involved four types of steel fibers, eight compressive strengths of VHSC matrixes, and two normal concrete strengths. Test results have shown that Pullout behavior of different steel fiber reinforced VHSC composites is influenced by the matrix strength and fiber end condition (smooth, flat end, or hooked). Results reveal that both maximum pull-out load and total Pullout energy increases as matrix strength increases for all deformed fibers that did not rupture. The Test results also indicated that the increase in total Pullout energy is more significant than that in peak load.
Robe J Young - One of the best experts on this subject based on the ideXlab platform.
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analysis of the single fiber Pullout Test using raman spectroscopy part iii Pullout of nicalon fibers from a pyrex matrix
Journal of the American Ceramic Society, 1996Co-Authors: Xugang Yang, Damia J Anniste, Robe J YoungAbstract:Single-fiber Pullout specimens consisting of Nicalon fibers and a Pyrex-glass matrix were fabricated using a specially designed, simple mold. Raman spectroscopy was used to map the distribution of fiber strain within the glass matrix following deformation of the fiber section in air, and the results were compared with those predicted by theoretical analyses. It was demonstrated that the behavior also could be modeled using a partial debonding theory and that the force balance equilibrium allowed the variation of inter-facial shear stress along the interface to be derived. The partial debonding theory showed that debonding occurred at an interfacial shear stress of 60 ± 20 MPa and that the friction shear stress following debonding was 23 ± 8 MPa for the specimen investigated. Furthermore, it was shown that the fracture toughness of the fiber-matrix interface was 1.8 ± 0.6 J·m–2.
Surendra P Shah - One of the best experts on this subject based on the ideXlab platform.
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use of a crack bridging single fiber Pullout Test to study steel fiber cementitious matrix composites
Journal of the American Ceramic Society, 2004Co-Authors: Thomas C Easley, K T Fabe, Surendra P ShahAbstract:The fracture process of steel fiber/cementitious matrix composites has been studied using a single-fiber Pullout Test that permits detailed measurements of the load-crack opening displacement relationship during fiber debonding and unloading. Using a suitable analytical model, the interfacial fracture energy and interfacial sliding friction have been calculated for composites incorporating steel fibers with cement paste or mortar matrices. Comparison of theoretical debonding curves with the experimental data show that the model accurately represents the fiber debonding process, except for a decrease in interfacial sliding friction due to wear of matrix asperities at the interface. Differences between the calculated interfacial properties of several specimens are associated with changes in the interfacial microstructure.
