Second Gradient Linear and Nonlinear Constitutive Models of Architectured Materials: Static and Dynamic Behaviors

2021 ◽  
pp. 53-71
Author(s):  
Yosra Rahali ◽  
Hilal Reda ◽  
Benoit Vieille ◽  
Hassan Lakiss ◽  
Jean-François Ganghoffer
2019 ◽  
Vol 25 (3) ◽  
pp. 739-767 ◽  
Author(s):  
Emilio Barchiesi ◽  
Simon R Eugster ◽  
Francesco dell’Isola ◽  
François Hild

Bi-pantographic fabrics are composed of two families of pantographic beams and correspond to a class of architectured materials that are described in plane as second-gradient 2D continua. On a discrete level, a pantographic beam is a periodic arrangement of cells and looks like an expanding barrier. The materialization of a bi-pantographic fabric made from polyamide was achieved by additive manufacturing techniques. Starting from a discrete spring system, the deformation energy of the corresponding continuum is derived for large strains by asymptotic homogenization. The obtained energy depends on the second gradient of the deformation through the rate of change in orientation and stretch of material lines directed along the pantographic beams. Displacement-controlled bias extension tests were performed on rectangular prototypes for total elastic extension up to 25%. Force–displacement measurements complemented by local digital image correlation analyses were used to fit the continuum model achieving excellent agreement.


1998 ◽  
Vol 1624 (1) ◽  
pp. 225-230 ◽  
Author(s):  
Chuntao Zhang ◽  
Ian D. Moore

Thermoplastic pipes are being used increasingly for water supply lines, storm sewers, and leachate collection systems in landfills. To facilitate limit states design for buried polymer pipes, nonlinear constitutive models have recently been developed to characterize the highly nonlinear and time-dependent material behavior of high-density polyethylene (HDPE). These models have been implemented in a finite element program to permit structural analysis for buried HDPE pipes and to provide information regarding performance limits of the structures. Predictions of HDPE pipe response under parallel plate loading and hoop compression in a soil cell are reported and compared with pipe response measured in laboratory tests. Effects on the structural performance of pipe material nonlinearity, geometrical nonlinearity, and backfill soil properties were investigated. Good correlations were found between the finite element predictions and the experimental measurements. The models can be used to predict pipe response under many different load histories (not just relaxation or creep). Work is ongoing to develop nonlinear constitutive models for polyvinylchloride and polypropylene to extend the predictive capability of the finite element model to these materials.


2020 ◽  
pp. 108128652097167
Author(s):  
Francesco D’Annibale ◽  
Arnaldo Casalotti ◽  
Angelo Luongo

In this paper, the static behavior of an elastic beam resting on a rigid substrate is investigated. The structure lies on a rigid substrate and exchanges with it tangential forces, in correspondence with a finite number of contact points. These actions entail extension of the beam in the longitudinal direction together with a negligible bending, owing to the small eccentricity between the beam’s axis line and the rigid substrate. The beam obeys a linear elastic law, while, at the interface, different nonlinear constitutive models are considered to account for stick-slip phenomena due to friction, as well as wear due to abrasion. It is assumed that the contact points are a-priori known, thus entailing that the structural system can be treated as naturally discrete. The static problem is accordingly shown to be governed by a system of nonlinear ordinary differential equations in time, which rules, in incremental form, the equilibrium at the contact points in the longitudinal direction. A numerical solution for the equilibrium equations is carried out, under different imposed time histories of the longitudinal displacement assigned at the boundary. Numerical results are presented to compare and discuss the in-time evolution of the contact interactions between the beam and the substrate.


2010 ◽  
Vol 456 ◽  
pp. 67-76 ◽  
Author(s):  
Jun Ma ◽  
Yan Jiang Chen ◽  
Li Peng Liu

A finite-element model for CFST members using a 3D composite beam fiber element is presented which accounts for the nonlinear constitutive models of steel and concrete separately. The model is proved to be valid by comparing the computational results of some test specimens with their experimental data. Using this model, a CFST arch bridge’s seismic response was calculated. The result indicated that the magnitude of displacements and moments at arch crown increases up to 10 percent caused by CFST hysteretic behavior which should be seriously considered during seismic design. Some measures and suggestions bring forward to guide the design and construction of this type of bridge.


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