Study On The Form Of Network And Its Mechanical Mechanical Properties

According to the braided principle of knotted netting,warp-knitted knotless netting and braided knotless netting,this paper studies the tensile strength,fatigue strength and structural stability of the netting knots by focusing on the structural characteristics of three kinds of mesh fabric.The research direction is divided into three parts: theoretical research,simulation research and experimental research.According to the braided structure characteristics of three kinds of netting knots,the braided process of three kinds of net knots is studied.In order to solve the problem of single variable in the contrast test,the braided scheme was designed and the sample was braided.According to the braided scheme,three kinds of three-dimensional theoretical models are constructed respectively.By means of rotation of the base circle and intersecting of the surface,the model with knotted netting made of four yarns was obtained.Based on the two-dimensional image method,the projection track of the interwoven yarn is designed.Then the projection track was synthesized into the three-dimensional space track,and the three-dimensional model of the warp knitted knotless netting was obtained.By breaking the yarn trajectory into discrete motions along the X,Y,and Z axes,the yarn trajectory was determined by the joint movement of the yarn carrier and the traction device,Finally,the three-dimensional model of braided knotless netting was obtained by using spline curve optimization.The finite element software was used to simulate the tensile test of the netting knots model,and the stress-strain distribution law under the same tensile load was obtained.The results of finite element analysis show that the most serious stress concentration of the three kinds of netting occurs first at the joint position of netting knot and netting foot.The torsion and bending degree of the yarn have a great influence on the mechanical properties of netting.Under the same load,the braided knotless netting yarns have the same deformation trend along the axis,and the warp knotless netting yarns have the largest deformation trend along the axis.The net foot yarns have the same deformation trend along the axis,and the tensile deformation of the yarn at the netting knot is not obvious.It can be concluded from the comprehensive analysis that both the netting foot and the netting knot have good structural stability.Tensile fracture test and tensile cycle test were carried out to obtain the tensile stressstrain curves and tensile cycle stress-strain curves.The tensile fracture properties and fatigue resistance of the three kinds of mesh fabrics were analyzed,and the correctness of the finite element analysis was verified.The test results show that the three kinds of mesh fabrics all cause stress concentration and damage at the netting knot,which is in accordance with the stress distribution law in the finite element analysis.By comparing the stress-strain curves of the experimental and simulated values,the reliability of the three-dimensional structure model and the correctness of the finite element analysis are proved.The braided structure of the netting knot is an important factor affecting its mechanical properties.Under the same conditions,such as material,netting foot density and length,the tensile properties,fatigue resistance and structural stability of the mesh fabric are greatly different.According to the comprehensive analysis,the braided knotless netting has the highest breaking strength,the knotted nettng has the best fatigue resistance and stability,and the warp knitted knotless net has the best elongation.