Analysis Of Dynamic Properties And Wind Induced Response Of Tensioned Flat Membranes With Wrinkling Deformation

Membranes featured with lightweight and easy-making can be widely used in the field of civil engineering and aerospace.Due to the property of low flexural rigidity,wrinkling will occur readily for the membrane structure under compressional load.Membrane wrinkles may not only affect the surface accuracy and stability of a structure,but also change its stress distributions and out-of-plane deformation,and further have an influence on the vibration characteristics and aerodynamic behavior.The membrane structure will be susceptible to the wind loads after the membrane is wrinkled,which will make the structure lose its stress and stiffness perpendicular to the wrinkle direction.Therefore,it is of great significance to study the dynamic characteristics and the dynamic response of wrinkled membranes under wind load.Previous studies focused on the vibration characteristics and dynamic response of wrinkled membrane under different boundary conditions without taking account for the effect of pre-stress,the influence of post-wrinkled deformation as well as the geometric and material's variation.However,these factors also have a significant impact on the vibration characteristics and dynamic behavior of the membrane.In this paper,thin membranes are numerically studied to explore the influences of pre-stress,boundary conditions,geometric and material's variation on the vibration properties.Also,the study on the influences of wind speed,wind direction,pre-stress and boundary conditions to the wind-induced response of wrinkled membranes were also provided.The main content of this paper is presented as the following:1.Based on the shell stability theory,a rectangular membrane under shear and a circular membrane under torsion are numerically analyzed with shell elements.The results obtained from the established model make a good agreement with those from experiments and theory,which can be verified that the proposed finite element model has good accuracy.2.After that,based on the proposed numerical model,the effects of pre-stress,boundary conditions,geometric and material's variation on the vibration properties of membranes were studied.The results indicate that(i),the mode shapes were mainly related to the stress distribution of the membrane structure and can be characterized by three stages:the no-wrinkle stage,the expansion stage and the stable stage;(ii),the pre-stress,boundary conditions may also have a great influence on similar mode shape and frequency;(iii),the regularity with Poisson ratio is different under different shear displacement;(iv),the membrane thickness and modulus of elasticity mainly affect the frequency.3.At last,the paper numerically studied the effects of wind speed,wind direction,pre-stress and boundary conditions on the wind-induced response of membranes based on the wind tunnel test data.The results indicate that,(i)the displacement and stress will become large with the increasing of the wind speed;(ii),the effect of wind direction is quite complex;(iii),increasing the pre-tension and shear displacement can diminish the overall upward displacement of the membrane surface and enlarge the stresses.