Figure 1 - uploaded by Marianna Coelho
Content may be subject to copyright.
Source publication
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...
Similar publications
Marine composite materials typically exhibit significant rate dependent response characteristics when subjected to extreme dynamic loading conditions. In this work, a strain-rate dependent continuum damage model is incorporated with multicontinuum technology (MCT) to predict damage and failure progression for composite material structures. MCT trea...
The plasticity models in finite element codes are often not able to describe the cyclic plasticity phenomena satisfactorily. Developing a user-defined material model is a demanding process, challenging especially for industry. Open-source Code_Aster is a rapidly expanding and evolving software, capable of overcoming the above-mentioned problem with...
Soil liquefaction can be attributed to the combining effect of three main causes which are cohesionless soil, high pore water pressure, and earthquake motion. As a numerical analysis software often being used in geotechnical field, Plaxis2D is capable of solving soil liquefaction problems. During Plaxis2D simulation for liquefaction, ground water t...
The stress-strain characteristics of nonlinear visco-elastoplastic architectural fabrics show a mechanically saturating behaviour in cyclic tensile tests: stiffness changes decline, the increase of permanent strain decreases and the nonlinear material behaviour increasingly approaches a linear behaviour. Appropriate stress-strain paths for elastic...
Background:
The FEM is often used in investigations of dentin loading conditions; however, its anisotropy is mostly neglected.
Objectives:
The purpose of the study was to evaluate the anisotropy and the elastic properties of an equivalent homogenous material model of human dentin as well as to compare isotropic and anisotropic dentin FE-models....
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.
