Elasto-viscoplastic material model considering larges trains for EFTE-foils

Abstract

The growing use of ETFE-Foils in pneumatic structures has motivated the research in material models for thermoplastic polymeric. This type of polymer is more resistant to solvents and other chemicals. The lightweight of the ETFE foil is one of the most important features that motivates its use in structural buildings. Moreover, it has been applied often to roofs, resulting in low costs for the foundation. The translucency property is advantageous, because it allows the utilization of natural light, reducing the use of artificial light. Another property related with resource consumption is the anti- adhesive nature of ETFE. This property means that roofs and atria need to be cleaned less frequently, leading to a reduction in the cost of the building maintenance. ETFE membrane structures clearly present large deformations by which the small strain material model fails to give good results. Beyond this behavior some experiments showed the dependency of the ETFE mechanical properties with temperature. These experiments indicated viscoplastic material behavior, characterized by different responses for different strain rates / load rates and different temperatures. The present work shows an implementation in a finite element software of an elasto- viscoplastic material model considering large strains for the ETFE membranes. The parameters were obtained with uniaxial experiments analysis from literature. The results of the numerical model show good agreement with the experiments.