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This work presents a numerical model for the simulation of the behavior of pneumatic structures made of ETFE
material. The model is applied to the simulation of a Burst-test for which experimental measurements are available. In the experiment, samples of ETFE-foil were fixed in a bubble inflation test device between an aluminium plate and an alumin...
Contexts in source publication
Context 1
... applicability of the material models present in section 2 for ETFE membranes will be evaluated based on experimental results. Figure 3 presents the experimental data from uniaxial and biaxial test of ETFE from works of Moritz [7], Galliot and Luchsinger [5], and DuPONT Tefzel [4] and an adjusted von Mises yield curve. This yield surface was generated considering an yield stress of 16MPa . ...
Context 2
... yield surface was generated considering an yield stress of 16MPa . Figure 3 shows that the von Mises criteria is a good approximation for the experimental data for the ETFE material. ETFE-foils behave as membranes, therefore the analyses will be carried out considering plane stress state. ...
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Citations
... Although various sophisticated models are presented for orthotropic materials (Wang et al. 2017), properties of membrane fabrics are often simplified to isotropic or orthotropic linear elastic materials. Therefore, the equilibrium shape analysis for specified cutting pattern can be formulated as a forced displacement analysis problem, which can be solved by geometrically nonlinear analysis (Coelho et al. 2014a;Gosling and Lewis 1996), dynamic relaxation method (Barnes 1988), or minimization of the total strain energy (Mosler 2008;Bouzidi and Le Van 2004). However, there exists difficulty for formfinding and equilibrium shape analysis of pneumatic membrane structures that are formed and strengthened by applying air pressure (Coelho et al. 2014b;Bown and Wakefield 2015). ...
... ETFE film is usually modeled as an elasto-plastic material with von Mises yield criterion (Yoshino and Kato 2016; Coelho et al. 2014a). However, the method of cutting pattern design described in Sect. 3 is applicable only to elastic membrane material. ...
A computationally efficient method is presented for approximate optimization of cutting pattern of frame-supported and pneumatic membrane structures. The plane cutting sheet is generated by minimizing the error from the shape obtained by reducing the stress from the desired curved shape. The equilibrium shape is obtained solving a minimization problem of total strain energy. The external work done by the pressure is also incorporated for analysis of pneumatic membrane. An approximate method is also proposed for analysis of an Ethylene TetraFluoroEthylene (ETFE) film, where elasto-plastic behavior is modeled as a nonlinear elastic material under monotonic loading condition. Efficiency of the proposed method is demonstrated through examples of a frame-supported PolyVinyl Chloride (PVC) membrane structure and an air pressured square ETFE film.
... More recent studies have focused on specific aspects like creep [9], behavior at low temperatures [10], viscous properties [11], uniaxial deformation [5], cyclic mechanical properties [12] or burst [13], among others. ...
A nonlinear, time dependentthermo-viscoelasticmaterial model has been developed at Caltech to represent thin polyethylene based films, typically used as the shell for high altitude balloons. Thismaterial model has been implemented in the aerospace industry for several yearsin support of the design and analysis of stratospheric balloons. Viscoelastic material models have already been successfully applied in a finite element (FE)environment for modelling of such balloons. Ethylene tetrafluoroethylene (ETFE) is fluorine-basedplasticwhich also shows asignificant time-dependent and temperature-dependent response under load.The Caltech material model can therefore be factored and calibrated in order to be used for the design and analysis of ETFE films.In doing this a more precise and controlled analysis of this type of structures can be achieved. The most remarkable advantage of having such a complete tool is how the design process gets simplifiedon one handbut at the same time better understood and more accurate. This gainedprecisionmay be critical for some extreme cases, as will be exemplified in this paper. This comprehensive approach can also dispense the designer with some of the factors currently required to account for biaxial stress, temperature variation and long-term effects. A yield locuscan be also defined to aid in the design and analysis tasks.
