scholarly journals An Extensive Review on the Viscoelastic-plastic and Fractural Mechanical Behaviour of ETFE Membranes

Author(s):  
Dániel Karádi ◽  
Dezső Hegyi

The present article is a review of ETFE (ethylene tetrafluoroethylene) material, with emphasis on the mechanical and fractural behaviour, considering that the material is becoming one of the most promising façades and roof materials due to its advantageous properties. This paper examines the basic chemical makeup of this copolymer and details the elastic-plastic and viscous properties through selected studies in the field. The paper also reviews the available phenomenological, continuum mechanical or rheological constitutive models focusing on the engineering application to the corresponding phenomena. A separate part of the article covers the existing fractural mechanical research on ETFE.

2005 ◽  
Vol 42 (4) ◽  
pp. 1066-1085 ◽  
Author(s):  
Kianoosh Hatami ◽  
Richard J Bathurst

The paper describes a numerical model that was developed to simulate the response of three instrumented, full-scale, geosynthetic-reinforced soil walls under working stress conditions. The walls were constructed with a fascia column of solid modular concrete units and clean, uniform sand backfill on a rigid foundation. The soil reinforcement comprised different arrangements of a weak biaxial polypropylene geogrid reinforcement material. The properties of backfill material, the method of construction, the wall geometry, and the boundary conditions were otherwise nominally the same for each structure. The performance of the test walls up to the end of construction was simulated with the finite-difference-based Fast Lagrangian Analysis of Continua (FLAC) program. The paper describes FLAC program implementation, material properties, constitutive models for component materials, and predicted results for the model walls. The results predicted with the use of nonlinear elastic-plastic models for the backfill soil and reinforcement layers are shown to be in good agreement with measured toe boundary forces, vertical foundation pressures, facing displacements, connection loads, and reinforcement strains. Numerical results using a linear elastic-plastic model for the soil also gave good agreement with measured wall displacements and boundary toe forces but gave a poorer prediction of the distribution of strain in the reinforcement layers.Key words: numerical modelling, retaining walls, reinforced soil, geosynthetics, FLAC.


1984 ◽  
Vol 1984 (343) ◽  
pp. 255-265 ◽  
Author(s):  
Hiroyoshi HIRAI ◽  
Eiji YANAGISAWA ◽  
Masao SATAKE

2006 ◽  
Vol 59 (3) ◽  
pp. 146-175 ◽  
Author(s):  
Frederick Bloom

A survey is provided of the various constitutive models that have been used to study the phenomena of wave propagation in soils. While different material models have been proposed for the response of soils, it is now generally understood that no single model may be used over the entire range of pressures which are typically studied. The constitutive models reviewed in this paper include a number of effective stress and multiphase models, the volume distribution function model, and various versions of the P−α model. Also discussed are classical elastic-plastic models, models possessing different elastic constants in loading and unloading, variable modulus models, and capped elastic-plastic models.


Author(s):  
M. R. Brake ◽  
D. S. Aragon ◽  
D. J. VanGoethem ◽  
H. Sumali

Impact is a wide-spread phenomenon in mechanical systems that can have a significant effect on the system’s dynamics, stability, wear, and damage. The simulation of impact in complex, mechanical systems, however, is often too computationally intensive for high fidelity finite element analyses to be useful as design tools. As a result, rigid body dynamics and reduced order model simulations are often used, with the impact events modeled by ad hoc methods such as a constant coefficient of restitution or a penalty stiffness. The consequences of the choice of contact model are studied in this paper for a representative multiple-degrees of freedom mechanical system. Four contact models are considered in the analysis: a constant coefficient of restitution model, two similar elastic-plastic constitutive models, and one dissimilar elastic-plastic constitutive model. The predictions of wear, mechanical failure, and stability are assessed for each of the contact models, and the subsequent effect on the system design is investigated. These results emphasize the importance of choosing a realistic contact model when simulations are being used to drive the design of a system.


1987 ◽  
Vol 58 (1) ◽  
pp. 33-39 ◽  
Author(s):  
Essam El-Magd ◽  
Karl-Josef Hellwig ◽  
Hans-Günter Höck ◽  
Mohamad Homayun

2011 ◽  
Vol 255-260 ◽  
pp. 209-214
Author(s):  
Xu Jie Sun ◽  
Jian Ping Cao ◽  
Wen Zhong Zheng

To make sure the seismic behavior of outer-jacketing mega frame for storey-adding, a low-cyclic loading test of prestressed concrete beam and a pseudo-static test of Mega frame were analyzed by elastic-plastic finite element program IDARC2D, compared with the test results, skeleton hysteretic curves and restoring force models of structural member were determined. They were used in IDARC2D to study the seismic behavior of mega frame for storey-adding. Some structures designed complied with the Code for Seismic Design of Buildings (GB50011-2001) and correlative literatures about collapse, these structures were reanalyzed after enhancing their seismic measures suitably, collapse were avoided. They are: the main frame of outer-jacketing mega frame in the zone of seismic fortification intensity 8 conforming to seismic grade 1-st, the height of mega frame under 50m conforming to seismic grade 2-nd and that over 50m conforming to seismic grade 1-st in zone of seismic fortification intensity 7. Research achievements will provide reference to engineering application of this structural system.


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