Tearing Behavior Of Architectural Coated Fabrics With Central Crack

Membrane structure has the advantages of novel and beautiful architectural shape,light weight,short construction period,good seismic performance and so on,and is widely used in large building structures.However,due to the degradation of membrane properties,the effect of sudden load and other factors,there are not a few cases of membrane structure buildings damaged during the service period.The main form of membrane structure failure is tear failure,which is mainly caused by the initial defect which decreases the tear resistance of membrane material.Therefore,in order to avoid tearing damage of membrane structure,it is necessary to clarify the tearing mechanism of membrane material with initial defects,and further study the influence of initial defects on static and dynamic properties of membrane structure.In this thesis,experiments,numerical simulation and theoretical analysis are used to explore the effect of central crack on the tearing properties of membrane materials and mechanical properties of membrane structure.The main work is as follows:(1)Study on single crack center tearing property of membrane material.The central tearing test was carried out on the membrane with single crack,and the effects of different initial crack lengths on the strain distribution,crack propagation law,failure mode and the theoretical value of stress intensity factor were discussed.The numerical model under the same working condition was established by the extended finite element method for comparative analysis.The results show that the crack length affects the tearing failure mode,and the specimen with larger crack size has obvious crack propagation phenomenon.The high strain region appears at the crack end during the tearing process and the area of the region increases with the crack propagation.The finite element model based on the extended finite element method can accurately grasp the law of crack propagation and obtain a more accurate numerical solution of the stress intensity factor.(2)Study on double crack center tearing property of membrane material.On the basis of the single crack center tear study,the double crack center tear test of membrane material was carried out.Considering the influence law of different initial crack length,crack inclination Angle,crack spacing and sample size on the tear resistance of membrane material,the prediction accuracy of failure strength of double crack center tear specimen was compared by three different classical theoretical models.The finite element model based on different material constitutive was established by ABAQUS software to simulate the tearing behavior of double-crack membrane.The results show that different crack characteristics affect the tear failure mode of double-crack specimens.The change of crack length has the greatest effect on the failure strength of the specimen,while the change of crack spacing has the least effect.Compared with the linear elastic material constitutive model,the numerical simulation results of nonlinear material constitutive model based on Fabric keyword are better.The classical stress field method has the worst effect on the failure strength prediction of double-crack central tearing specimen.(3)Study the static and dynamic characteristics of membrane structure considering the central crack.Static jacking tests and dynamic tests were carried out on the one-way tensioning mask structure with central crack.Considering the influence of different crack characteristics on the mechanical properties of the membrane structure,the finite element model under the same working condition was established to further study the mechanical response and internal force transfer law of the membrane structure with central crack under impact load.The results show that the larger the crack length is and the closer the crack is to the jacking zone,the larger the load required for cracking of the film surface crack is.The amplitude attenuation rate of each measuring point on the crack film surface decreases with the increase of impact height and crack length.Under the impact load,the film surface with central crack will form a high stress zone near the impact point and at both ends of the crack.