Structural Membranes: International Conference on Textile Composites and Inflatable Structures
http://hdl.handle.net/2117/103884
2022-05-19T09:13:12ZIssues with management, maintenance and upkeep in ETFE enclosures
http://hdl.handle.net/2117/186361
Issues with management, maintenance and upkeep in ETFE enclosures
Ward, James R.; Chilton, John; Rowell, Lance H.
Ethylene tetra-fluoro-ethylene (ETFE) foil, as a single layer or as multi-layer inflated cushions, has been in used in the building industry for nearly 30 years as a medium to cover and clad both façades and atria. Its longevity has been well publicised and proven with many projects showing little or no signs of degradation.
The number of ETFE foil structures has been steadily rising in recent years, and with this the inevitable need for maintenance has also risen. The anticipated life of ETFE foil is now suggested to be as long as 50 years [1], and as with any other building material, regular inspections are necessary to ensure the continued optimal operation of the enclosure.
2020-05-05T11:54:54ZWard, James R.Chilton, JohnRowell, Lance H.Ethylene tetra-fluoro-ethylene (ETFE) foil, as a single layer or as multi-layer inflated cushions, has been in used in the building industry for nearly 30 years as a medium to cover and clad both façades and atria. Its longevity has been well publicised and proven with many projects showing little or no signs of degradation.
The number of ETFE foil structures has been steadily rising in recent years, and with this the inevitable need for maintenance has also risen. The anticipated life of ETFE foil is now suggested to be as long as 50 years [1], and as with any other building material, regular inspections are necessary to ensure the continued optimal operation of the enclosure.Effects on elastic constants of technical membranes applying the evaluation methods of MSAJ/M-02-1995
http://hdl.handle.net/2117/186360
Effects on elastic constants of technical membranes applying the evaluation methods of MSAJ/M-02-1995
Uhlemann, Jörg; Stranghöner, Natalie; Schmidt, Herbert; Saxe, Klaus
The non-linear load-deform ation behaviour of textile m embranes highly depends on the ratio of the applied m embrane forces in warp and weft direct ion (called load ratio hereafter). In practice, usually for each membrane structure the biaxial material behaviour is determined experimentally. The Japane se Standard MSAJ/M-02-1995 describes a standardized biaxial testing procedure. To achie ve input parameters for the structural design
process, the commentary to this standard expl ains some methods how to evaluate one set of fictitious elastic constants based on the expe rimental results which, sim ultaneously, envelop different load ratios and do not reflect the non -linear material behaviour anymore. Different approaches of determining such simplified, fictit ious elastic constants have been investigated in the present contribution, with m ainly two co nclusions: firstly, to have one set of elastic constants by means of which all types of structures under all types of loading can be treated is a highly disputable objective a nd secondly, the values of the determined elastic constants react quite sensitively on the underlying determination option, which should be defined by the users themselves.
2020-05-05T11:50:55ZUhlemann, JörgStranghöner, NatalieSchmidt, HerbertSaxe, KlausThe non-linear load-deform ation behaviour of textile m embranes highly depends on the ratio of the applied m embrane forces in warp and weft direct ion (called load ratio hereafter). In practice, usually for each membrane structure the biaxial material behaviour is determined experimentally. The Japane se Standard MSAJ/M-02-1995 describes a standardized biaxial testing procedure. To achie ve input parameters for the structural design
process, the commentary to this standard expl ains some methods how to evaluate one set of fictitious elastic constants based on the expe rimental results which, sim ultaneously, envelop different load ratios and do not reflect the non -linear material behaviour anymore. Different approaches of determining such simplified, fictit ious elastic constants have been investigated in the present contribution, with m ainly two co nclusions: firstly, to have one set of elastic constants by means of which all types of structures under all types of loading can be treated is a highly disputable objective a nd secondly, the values of the determined elastic constants react quite sensitively on the underlying determination option, which should be defined by the users themselves.Determination of the response of coated fabrics under biaxial stress: comparison between different test procedures
http://hdl.handle.net/2117/186359
Determination of the response of coated fabrics under biaxial stress: comparison between different test procedures
Galliot, Cedric; Luchsinger, Rolf H.
The biaxial response of a PVC-coated polyester fabric is investigated using three different test procedures. The influence of the test procedure on the experimental data is discussed. A new approach based on a response domain is proposed.
2020-05-05T11:45:13ZGalliot, CedricLuchsinger, Rolf H.The biaxial response of a PVC-coated polyester fabric is investigated using three different test procedures. The influence of the test procedure on the experimental data is discussed. A new approach based on a response domain is proposed.Mechanics of local buckling in wrapping fold membrane
http://hdl.handle.net/2117/186353
Mechanics of local buckling in wrapping fold membrane
Satou, Yasukata; Furuya, Hiroshi
Mechanics of a local buckling, which is induced by wrapping fold of a creased membrane, is discussed experimentally, theoretically, and numerically in this paper to examine the condition for the local buckling. The theoretical analysis is performed by introducing one-dimensional wrapping fold model, and the dominant parameters of the condition for the local buckling are obtained, which are expressed by the tensile force, the
membrane thickness, and the radius of the center hub. The experimental results indicate that the interval of the local buckling is proportional to the diameter of the center hub, and the results are qualitatively agreement with the FEM results.
2020-05-05T11:41:54ZSatou, YasukataFuruya, HiroshiMechanics of a local buckling, which is induced by wrapping fold of a creased membrane, is discussed experimentally, theoretically, and numerically in this paper to examine the condition for the local buckling. The theoretical analysis is performed by introducing one-dimensional wrapping fold model, and the dominant parameters of the condition for the local buckling are obtained, which are expressed by the tensile force, the
membrane thickness, and the radius of the center hub. The experimental results indicate that the interval of the local buckling is proportional to the diameter of the center hub, and the results are qualitatively agreement with the FEM results.Analysis of thermal evolution in textile fabrics using advanced microstructure simulation techniques
http://hdl.handle.net/2117/186352
Analysis of thermal evolution in textile fabrics using advanced microstructure simulation techniques
Römmelt, Matthias; August, Anastasia; Nestler, Britta; Kneer, Aron
Nowadays, membrane structures represent a modern construction element to be used as roof material in modern buildings or as design element in combination with traditional architecture. Membranes are mostly used in an outdoor environment. Therefore they are exposed to wind, radiation (solar and infrared), rain and snow. Specific membranes are three-dimensional fabrics which can be used as energy absorber or as insulation of membrane roofs. The applicability as energy absorber becomes important if the three-dimensional fabrics are designed as a porous flow channel streamed by air and convectively heated up. The transferred energy may be stored in a latent heat storage system.
Due to their porous structure, textile fabrics have a large heat-exchanging surface. If they are handled as homogenized porous structures, the heat transfer processes can not be described in a correct way. Therefore a microstructure model locally resolving all filaments of the three-dimensional fabrics has been formulated. By using an advanced meshing tool, a simulation technique has been developed taking into account the local
heat conduction properties of the different materials.
To analyse the heat transfer processes inside the three-dimensional fabrics, numerical simulations have been performed using the phase-field solver (Pace3D) of the Karlsruhe Institute of Technology and the commercial CFD-Solver StarCCM+. For a better understanding of the thermal behaviour of the fabrics, different thermal loads including thermal conduction in the microstructure (filaments) and convection by the surrounding air have been computed. The results show that the advanced simulation techniques allow to analyse the rate of conductive and convective heat transfer in three-dimensional fabrics. The results of the applied computational methods are compared.
2020-05-05T11:38:14ZRömmelt, MatthiasAugust, AnastasiaNestler, BrittaKneer, AronNowadays, membrane structures represent a modern construction element to be used as roof material in modern buildings or as design element in combination with traditional architecture. Membranes are mostly used in an outdoor environment. Therefore they are exposed to wind, radiation (solar and infrared), rain and snow. Specific membranes are three-dimensional fabrics which can be used as energy absorber or as insulation of membrane roofs. The applicability as energy absorber becomes important if the three-dimensional fabrics are designed as a porous flow channel streamed by air and convectively heated up. The transferred energy may be stored in a latent heat storage system.
Due to their porous structure, textile fabrics have a large heat-exchanging surface. If they are handled as homogenized porous structures, the heat transfer processes can not be described in a correct way. Therefore a microstructure model locally resolving all filaments of the three-dimensional fabrics has been formulated. By using an advanced meshing tool, a simulation technique has been developed taking into account the local
heat conduction properties of the different materials.
To analyse the heat transfer processes inside the three-dimensional fabrics, numerical simulations have been performed using the phase-field solver (Pace3D) of the Karlsruhe Institute of Technology and the commercial CFD-Solver StarCCM+. For a better understanding of the thermal behaviour of the fabrics, different thermal loads including thermal conduction in the microstructure (filaments) and convection by the surrounding air have been computed. The results show that the advanced simulation techniques allow to analyse the rate of conductive and convective heat transfer in three-dimensional fabrics. The results of the applied computational methods are compared.Form-finding of extensive tensegrity using truss elements and axial force lines
http://hdl.handle.net/2117/186350
Form-finding of extensive tensegrity using truss elements and axial force lines
Matsuo, Aya; Obiya, Hiroyuki; Ijima, Katsushi; Zakaria, Muhammad Nizam Bin
Tensegrity structure, which consists of cables and struts, are expected to be used as systems for cosmological, foldable and/or inflatable structures. The equilibrium shape of the tensegrity can be determined by iteration of solving the tangent stiffness equation. Here, it is rational to use the truss elements for struts and the axial force line elements for cables. In this study, a way to find the shapes of "extensive tensegrity", which counts their self-weight and permits support conditions of statically indeterminate. As results of numerical examples, even the case where many solutions exist under the same loading conditions like the tower tensegrity, expected one equilibrium solution can be obtained, and its equilibrium path can be drawn.
2020-05-05T11:28:42ZMatsuo, AyaObiya, HiroyukiIjima, KatsushiZakaria, Muhammad Nizam BinTensegrity structure, which consists of cables and struts, are expected to be used as systems for cosmological, foldable and/or inflatable structures. The equilibrium shape of the tensegrity can be determined by iteration of solving the tangent stiffness equation. Here, it is rational to use the truss elements for struts and the axial force line elements for cables. In this study, a way to find the shapes of "extensive tensegrity", which counts their self-weight and permits support conditions of statically indeterminate. As results of numerical examples, even the case where many solutions exist under the same loading conditions like the tower tensegrity, expected one equilibrium solution can be obtained, and its equilibrium path can be drawn.An orthotropic membrane model replaced with line-members and the large deformation analysis
http://hdl.handle.net/2117/186347
An orthotropic membrane model replaced with line-members and the large deformation analysis
Ijima, Katsushi; Obiya, Hiroyuki; Kido, Kota
The paper proposes a method for analyzing large deformation of membrane structures by replacing the structures with elements composed line-members. The replacement has the advantage that the structural model is completely compression-free, so that the analysis always has a unique equilibrium solution without falling into multi equilibrium
problems and the method is stable and easy even for how large deformation.
2020-05-05T11:20:54ZIjima, KatsushiObiya, HiroyukiKido, KotaThe paper proposes a method for analyzing large deformation of membrane structures by replacing the structures with elements composed line-members. The replacement has the advantage that the structural model is completely compression-free, so that the analysis always has a unique equilibrium solution without falling into multi equilibrium
problems and the method is stable and easy even for how large deformation.Evaluation of the structural behavior of textile covers subjected to variations in weather conditions
http://hdl.handle.net/2117/186346
Evaluation of the structural behavior of textile covers subjected to variations in weather conditions
Hernández, Carlos H.
A simplified model of an anticlastic membrane is that of two perpendicular ropes, which meet at a point. If the ropes are tensed in opposite directions, the meeting point becomes is fixed. As we increase the tension in the two ropes, more and more force will be required to move the meeting point of the two ropes. In other words, the system becomes more rigid when the tension of the ropes is increased and when applying an external force it will deform less. The tension applied to a cable system or an anticlastic membrane for it to become more rigid is called pretension. A membrane or anticlastic net has an adequate structural behavior only if it is in a tensed state.[1]
Loss of pretension reduces the rigidity of the system, increasing its deformation due to external loads. If loss of pretension exceeds certain limits, the membrane will start to flutter or will be deformed, with the risk of accumulating water or snow, in both cases compromising the durability of the membrane. Therefore, it is of utter importance to know and be able to predict the process of loss of pretension in order to establish maintenance plans that allow optimal levels of initial tension in the anticlastic structures, avoid that loss of pretension reaches critical levels. Loss of pretension is due to the natural behavior of the material, but additionally, there are external factors that influence loss of pretension of the membranes, among these, we can mention the weather as a factor that affects tensional life of membranes.
In this work we will try to prove this hypothesis. In order to do this, the first stage will be the development of a trial bench that allows us to study the effect of superficial temperature, humidity and wind loads on the loss of pretension. The trial bench can reproduce, in a controlled and independent way, each one of the different variables of interest to this study. It allows us to study these variables in physical scale models and with accelerated cycle processes, which can in less time, simulate the behavior of the membranes in their normal life
cycle, lowering the cost of the study. On the other hand, the result of these studies will let us validate a mathematical model that is developed at the same time.
2020-05-05T11:17:05ZHernández, Carlos H.A simplified model of an anticlastic membrane is that of two perpendicular ropes, which meet at a point. If the ropes are tensed in opposite directions, the meeting point becomes is fixed. As we increase the tension in the two ropes, more and more force will be required to move the meeting point of the two ropes. In other words, the system becomes more rigid when the tension of the ropes is increased and when applying an external force it will deform less. The tension applied to a cable system or an anticlastic membrane for it to become more rigid is called pretension. A membrane or anticlastic net has an adequate structural behavior only if it is in a tensed state.[1]
Loss of pretension reduces the rigidity of the system, increasing its deformation due to external loads. If loss of pretension exceeds certain limits, the membrane will start to flutter or will be deformed, with the risk of accumulating water or snow, in both cases compromising the durability of the membrane. Therefore, it is of utter importance to know and be able to predict the process of loss of pretension in order to establish maintenance plans that allow optimal levels of initial tension in the anticlastic structures, avoid that loss of pretension reaches critical levels. Loss of pretension is due to the natural behavior of the material, but additionally, there are external factors that influence loss of pretension of the membranes, among these, we can mention the weather as a factor that affects tensional life of membranes.
In this work we will try to prove this hypothesis. In order to do this, the first stage will be the development of a trial bench that allows us to study the effect of superficial temperature, humidity and wind loads on the loss of pretension. The trial bench can reproduce, in a controlled and independent way, each one of the different variables of interest to this study. It allows us to study these variables in physical scale models and with accelerated cycle processes, which can in less time, simulate the behavior of the membranes in their normal life
cycle, lowering the cost of the study. On the other hand, the result of these studies will let us validate a mathematical model that is developed at the same time.A new double curved element for technical textile analysis with bending resistance
http://hdl.handle.net/2117/186345
A new double curved element for technical textile analysis with bending resistance
Hegyi, Dezsö
A new double curved spatial element was developed to analyze textile structures. It has a bending resistance beside the inplane stiffness. The element is based on a 8-node double curved membrane element1. To find the equilibrium solution the Total Lagrange strategy is used with the dynamic relaxation method (DRM). Deformations are calculated with a continuum mechanical method.
2020-05-05T11:11:40ZHegyi, DezsöA new double curved spatial element was developed to analyze textile structures. It has a bending resistance beside the inplane stiffness. The element is based on a 8-node double curved membrane element1. To find the equilibrium solution the Total Lagrange strategy is used with the dynamic relaxation method (DRM). Deformations are calculated with a continuum mechanical method.Homogenization and modeling of fiber structured materials
http://hdl.handle.net/2117/186276
Homogenization and modeling of fiber structured materials
Fillep, Sebastian; Steinmann, Paul
For the mechanical modeling and simulation of the heterogeneous composition of a fiber structured material, the material properties at the micro level and the contact between the fibers have to be taken into account. The material behavior is strongly influenced by the material properties of the fibers, but also by their geometrical arrangement. In consideration of the different length scales the problem involves, it is necessary to introduce a multi scale approach based on the concept of a representative volume element (RVE). For planar structures like technical textiles the macromodel is discretized by shell elements. In contrast the microscopic RVE is modeled with three dimensional elements to account for the contact between the fibers. The macro-micro scale transition requires a method to impose the deformation at a macroscopic point onto the RVE by suited boundary conditions. The reversing scale transition, based on the Hill-Mandel condition, requires the equality of the macroscopic average of the variation of work on the RVE and the local variation of the work on the macroscale. For the micromacro transition the averaged forces and the resulting moments have to be extracted by a homogenization scheme. From these results an effective constitutive law can be derived.
2020-05-05T07:45:14ZFillep, SebastianSteinmann, PaulFor the mechanical modeling and simulation of the heterogeneous composition of a fiber structured material, the material properties at the micro level and the contact between the fibers have to be taken into account. The material behavior is strongly influenced by the material properties of the fibers, but also by their geometrical arrangement. In consideration of the different length scales the problem involves, it is necessary to introduce a multi scale approach based on the concept of a representative volume element (RVE). For planar structures like technical textiles the macromodel is discretized by shell elements. In contrast the microscopic RVE is modeled with three dimensional elements to account for the contact between the fibers. The macro-micro scale transition requires a method to impose the deformation at a macroscopic point onto the RVE by suited boundary conditions. The reversing scale transition, based on the Hill-Mandel condition, requires the equality of the macroscopic average of the variation of work on the RVE and the local variation of the work on the macroscale. For the micromacro transition the averaged forces and the resulting moments have to be extracted by a homogenization scheme. From these results an effective constitutive law can be derived.