Structural Design And Mechanism Research Of TPU/STF Fiber Hybrid Laminated Stab-proof Composite Materia

Flexible stab resistance composites have significant advantages of softness and flexibility compared with rigid and semi-rigid stab resistance materials.Flexible stab-proof composite material uses high performance fiber fabric to achieve E1 class protection by means of multi-layer fabric overlay.The layering of fabric leads to an increase in mass and thickness,which seriously affects the comfort and flexibility of the wearer.The multi-layer fabric makes the material cost very high and can not be applied in the civil industry.In order to solve the above problems,the puncture deformation numerical model and finite element model of polyurethane（TPU）and shear thickening fluid（STF）composite fabric were established respectively,and the puncture deformation characteristics and mechanism of composite fabric were studied from macroscopic and mesoscopic scales.Based on the theoretical basis of improving the stab resistance performance through strain energy absorption,friction loss energy and viscosity loss energy,the synergistic stab resistance effect of STF and TPU is used.Experimental optimization of coating fluid parameters of TPU and STF is carried out through the three-dimensional fabric structure design and three-dimensional hybrid lamination design of composite materials.The experimental preparation and theoretical verification of lightweight and low-cost TPU/STF flexible stab resistance composite under E1 protection level were realized.The specific research contents are as follows:（1）The puncture deformation model and puncture finite element model of TPU/aramid and STF/aramid composite fabrics were established,and the numerical calculation and simulation were carried out.The deformation characteristics of TPU and STF composite fabrics during puncture and the mechanism of improvement of puncture resistance were studied from macroscopic and mesoscopic scales respectively.Both TPU and STF can increase the stress that yarn can bear and the area of fabric subjected to stress during fabric puncture.TPU mainly improves the puncture energy of composite fabric by increasing the absorption of strain energy,while STF mainly improves the puncture energy by increasing the friction loss and viscosity loss of composite fabric.（2）The theoretical basis is to improve strain energy,friction loss and viscosity loss to improve the performance of stab resistance.Experimental design of TPU and STF composite fabrics was carried out.TPU/STF two-dimensional stab resistant composite fabrics were constructed by coating TPU and impregnating STF respectively.The composition ratio of TPU coating solution and double scale compound STF was optimized.The effect of TPU and Si O₂ content in TPU coating solution on the anti-puncture performance of composite fabric and the force between yarns was studied.In addition,the effects of nano-scale and micron scale Si O₂ratio of double-scale compound STF on the interyarn friction performance and stab resistance performance were studied.The TPU coating solution and the double scale compound STF with the best effect on the improvement of stab resistance were optimized The effect of the synergistic effect of TPU and double scale compound STF on the stab resistance performance of TPU/STF two-dimensional anti-puncture composite fabric was investigated.The optimal TPU coating solution composition of 20wt%TPU and 3wt%Si O₂ has the best effect on the improvement of the fabric’s stab resistance,and the TPU coating solution in this proportion can make the fabric’s spike and knife force value increase by 850%and 215%,respectively.When the ratio of 12 nm to 0.5μm Si O₂ was2:1 in the double-scale compound STF,the stab resistance of the fabric was improved better,and the force of the spike and knife puncture was increased by 766%and 172%,respectively.When TPU and STF are both combined with fabric,they are first combined with fabric structure,and their anti-puncture mechanism plays a leading role in the puncture process.（3）In order to improve the stab-resistance performance of the composite fabric,the three-dimensional structure of the composite fabric was designed,and the stab resistance composite fabric with three-dimensional structure was introduced by needling.By using the method of needle-punched non-woven fabric as the surface layer and aramid plain weave fabric as the middle layer,the three dimensional stab resistant composite fabric was prepared.Then,TPU/STF three-dimensional stab resistant composite fabric was constructed by impregnating STF and coating TPU.Box-behnken Design of response surface was used to optimize the optimum needling processing parameters of three-dimensional composite fabric.The synergistic effect of acupuncture process and STF impregnation on the stab resistance of three-dimensional composite fabric was studied.The effects of STF impregnation pattern and TPU coating on the puncture resistance of TPU/STF three dimensional puncture resistance composite fabric were studied.The optimal process parameters were obtained as needles density 143.77 needles/cm² and needles depth 6.41 mm.The synergistic effect of STF and needling processing makes the three-dimensional stab-resistant composite fabric have the best stab-resistant performance,and the spike force and knife force are increased by 67%and 110%respectively compared with the laminated fabrics.The static spike and knife force values of SA/S/T with STF and TPU in the three-dimensional stab resistant composite fabric structure increased by 83%and 74%,respectively,compared with the specimens without STF and TPU,and increased by at least 86%and 120%compared with the TPU/STF two-dimensional stab resistant fabric structure.（4）In order to meet the requirements of E1 level stab protection and further give full play to the synergistic effect of TPU and STF,hybrid laminate structure design of STF/three dimensional stab resistant composite fabric and TPU/aramid composite fabric was carried out.The effect of lamination structure of composite fabric and lamination angle of aramid fabric on stab resistance was investigated.Finally,a lightweight and low-cost TPU/STF hybrid laminate stab-resistant composite material was prepared with STF/three-dimensional anti-stab composite fabric on the surface layer and TPU/aramid stab-resistant composite fabric on the bottom layer,which can meet the E1 protection requirements when the weight of composite is 10 kg/m².The cost of TPU/STF hybrid laminate stab-resistant composite is about 2.3～3.7 times lower than that of flexible stab-resistant material of high performance fabric,and the stab-resistant mechanism of composite fabric is verified by experiment.