Abstract
A coupled algorithm is proposed which first considers the creation of porous structure of the material and then the simulations of response of mechanical components with porous structure to a variable load history. The simulations are carried out by the Prandtl operator approach in the finite element method (FEM) which enables structural simulations of mechanical components subjected to variable thermomechanical loads. Temperaturedependent material properties and multilinear kinematic hardening of the material can be taken into account by this approach. Several simulations are then performed for a tensile-compressive specimen made of a generic porous structure and mechanical properties of Aluminium alloy AlSi9Cu3. Variable mechanical load history has been applied to the specimens under constant temperature conditions. Comparison of the simulation results shows a considerable elastoplastic stress-strain response in the vicinity of pores whilst the surface of the gauge-length of the specimen remains in the elastic region of the material. Moreover, the distribution of the pore sizes seems more influential to the stress-strain field during the loading than their radial position in the gauge-length.
Key Words
cyclic loading; elastoplasticity; finite element analysis; porous structure
Address
Domen Šeruga, Jernej Klemenc, Simon Oman and Marko Nagode: Faculty of Mechanical Engineering, University of Ljubljana, Aškerčeva 6, 1000 Ljubljana, Slovenia
Abstract
We have developed a model for estimating the parameters of viscous materials from indirect tensile tests for asphalt. This is a simple Burger nonlinear rheological two-cell model or standard model. At the same time, we begin to develop a more versatile and complex multi-cell model. The simple model is validated using experimental load-displacement results from laboratory tests: The recorded displacements are used as input values and the measured force data are simulated with the model. The optimal model parameters are estimated using the Levenberg-Marquardt method and a very good agreement between the experimental results and the model calculations is shown. However, not all parts of the model are active in the loading phase of the experiment, so we extended the validation of the model to the simulation of the relaxation behaviour. In this stage, the other model parameters are activated and the simulation results are consistent with the literature. At this stage, we have estimated the parameters only for the two-cell uniaxial model, but further work will include results for the multi-cell model.
Abstract
The comprehension and structural modeling of masonry constructions is fundamental to safeguard the integrity of built cultural assets and intervene through adequate actions, especially in earthquake-prone regions. Despite the availability of several modeling strategies and modern computing power, modeling masonry remains a great challenge because of still demanding computational efforts, constraints in performing destructive or semidestructive in-situ tests, and material uncertainties. This paper investigates the shear behavior of masonry walls by applying a plane-stress FE continuum model with the Modified Masonry-like Material (MMLM). Epistemic uncertainty affecting input parameters of the MMLM is considered in a probabilistic framework. After appointing a suitable probability density function to input quantities according to prior engineering knowledge, uncertainties are propagated to outputs relying on gPCE-based surrogate models to considerably speed up the forward problemsolving. The sensitivity of the response to input parameters is evaluated through the computation of Sobol' indices pointing out the parameters more worthy to be further investigated, when dealing with the seismic assessment of masonry buildings. Finally, masonry mechanical properties are calibrated in a probabilistic setting with the Bayesian approach to the inverse problem based on the available measurements obtained from the experimental loaddisplacement curves provided by shear compression in-situ tests.
Address
Giada Bartolini: Department of Energy, Systems, Territory and Construction Engineering, University of Pisa, Largo Lucio Lazzarino, 2, 56122 Pisa, Italy
Anna De Falco, Filippo Landi: Department of Civil and Industrial Engineering, University of Pisa, Largo Lucio Lazzarino, 2, 56122 Pisa, Italy
Abstract
In this study, a cyclic tensile test on a notched butterfly specimen made of woven glass fiber composite was performed on a modified Arcan fixture. During the mechanical test, the sample was monitored with a hybrid stereoscopic system comprised of two visible lights and one infrared camera. The visible light cameras were employed for kinematic measurements using a finite-element-based multiview correlation technique. A semi-hybrid correlation approach was followed, providing Lagrangian temperature fields of the Region of Interest. Due to the complex composite architecture and specimen shape, localized shearing was observed during the tensile loading. Furthermore, asymmetrical damage developed around the notches as revealed by localized strains and thermal hot spots.
Key Words
Arcan fixture; damage; full-field measurements; stereocorrelation; woven composite
Address
Andrija Zaplatić: Faculty of Mechanical Engineering and Naval Architecture, University of Zagreb, 10002 Zagreb, Croatia; Université Paris-Saclay, CentraleSupélec, ENS Paris-Saclay, CNRS, LMPS, 91190 Gif-sur-Yvette, France
Zvonimir Tomičević: Faculty of Mechanical Engineering and Naval Architecture, University of Zagreb, 10002 Zagreb, Croatia
Xuyang Chang: Université Paris-Saclay, CentraleSupélec, ENS Paris-Saclay, CNRS, LMPS, 91190 Gif-sur-Yvette, France
Ivica Skozrit: Faculty of Mechanical Engineering and Naval Architecture, University of Zagreb, 10002 Zagreb, Croatia
Stephane Roux, François Hild: Université Paris-Saclay, CentraleSupélec, ENS Paris-Saclay, CNRS, LMPS, 91190 Gif-sur-Yvette, France
Abstract
The paper deals with the finite element modelling of the free vibration and structural behavior of a particular four-floor reinforced concrete structure subjected to static equivalent seismic loads and supported by a shallow foundation system called SNSF (Spider Net System Footing). The two FE models are a simple 2D Matlab model and a detailed 3D model based on solid elastic elements using Altairworks (Hypermesh and Optistruct). Both models can simulate the soil structure interaction. We concentrate on the behavior of a representative cell involving two columns on five levels. The influence of the boundary conditions on the external vertical planes of the domain are duly studied. The Matlab model appears relevant for a primary estimation of frequencies and stiffness of the whole structure under vertical and lateral loads.
Key Words
altairworks; finite element modelling; free vibration; hypermesh software; Matlab software; Optistruct software; seismic loads; shallow foundation system SNSF
Address
Soelarso Soelarso: Laboratoire Avenues, Université de Technologie de Compiègne, Alliance Sorbonne Université,
CS 60319, 60203 Compiègne, France; Civil Engineering, Sultan Ageng Tirtayasa University, Jl. Jenderal Sudirman Km 3, Cilegon 42435, Indonesia
Jean-Louis Batoz: Laboratoire Roberval, Université de Technologie de Compiègne, Alliance Sorbonne Université,
CS 60319, 60203 Compiègne, France
Eduard Antaluca, Fabien Lamarque: Laboratoire Avenues, Université de Technologie de Compiègne, Alliance Sorbonne Université, CS 60319, 60203 Compiègne, France
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