Un nouvel élément fini à quatre nœuds pour l'analyse des coques composites

International audienceIn this paper, we present the theoretical formulation and the numerical validation of a new element "Discrete Mindlin Quadratic for Shell" of 4 nodes and 6 ddls per node. This one is based on variational model in displacement DDM (Displacement Discrete Mindlin) and on two modified Mindlin hypotheses. The model DMQS is considered as an interesting alternative to the finite element known as "Discrete Kirchhoff Quadrilateral" of thin shell without transverse shearing. It is validated on standard tests cases of isotropic and orthotropic shell.Dans ce travail, nous présentons la formulation théorique et la validation numérique d'un nouvel élément fini de coque isoparamètrique "Discrete Mindlin Quadratic for Shell" à 4 nœuds et 6 ddls par nœud. Celui-ci est basé sur un modèle variationnel en déplacement "Displacement Discrete Mindlin" et sur deux hypothèses modifiées de Mindlin. Le modèle DMQS est considéré comme une alternative intéressante à l'élément fini connu "Discrete Kirchhoff Quadrilateral" de coque mince sans cisaillement transverse. Il est validé sur des cas tests standards de coque isotrope et orthotrope

Un nouvel élément fini à quatre nœuds pour l'analyse des coques composites

International audienceIn this paper, we present the theoretical formulation and the numerical validation of a new element "Discrete Mindlin Quadratic for Shell" of 4 nodes and 6 ddls per node. This one is based on variational model in displacement DDM (Displacement Discrete Mindlin) and on two modified Mindlin hypotheses. The model DMQS is considered as an interesting alternative to the finite element known as "Discrete Kirchhoff Quadrilateral" of thin shell without transverse shearing. It is validated on standard tests cases of isotropic and orthotropic shell.Dans ce travail, nous présentons la formulation théorique et la validation numérique d'un nouvel élément fini de coque isoparamètrique "Discrete Mindlin Quadratic for Shell" à 4 nœuds et 6 ddls par nœud. Celui-ci est basé sur un modèle variationnel en déplacement "Displacement Discrete Mindlin" et sur deux hypothèses modifiées de Mindlin. Le modèle DMQS est considéré comme une alternative intéressante à l'élément fini connu "Discrete Kirchhoff Quadrilateral" de coque mince sans cisaillement transverse. Il est validé sur des cas tests standards de coque isotrope et orthotrope

Development of Alfa Fiber-Based Mortar with Improved Thermo-Mechanical Properties

This work deals with the development of a new composite based on mortar reinforced with optimally sized alfa fiber (AF). Experimental investigations of physical and thermo-mechanical properties of the new AF mortar composite are performed for AF weight fraction varying from 0% to 5%. This simple material preparation process is described and scanning electron microscopy (SEM) is undertaken to analyze the morphology of this composite. It shows a random dispersion of the AF into the mortar matrix. Physical properties such as open porosity, water absorption, and bulk density fluctuations with AF mass content are measured. Measured thermal conductivity is compared to the values generated by different prediction models. Good agreement, within 9.6%, is obtained with data predicted by Woodside–Messmer’s method. It is demonstrated that this simple blending of AF into mortar improves significantly the thermo-mechanical behavior of the new composite. An addition of 5% of AF weight content makes composite material lighter by about 15%, enhances its insulating thermal capabilities by about 57% and increases its heat diffusion damping rate by about 49%. Moreover, the composite mechanical (flexural and compressive) strength increases by up to 10% for an AF weight content of 1%

Mechanical and Thermal Behavior of Compressed Earth Bricks Reinforced with Lime and Coal Aggregates

The present study aims to investigate the effect of coal aggregates (CA) in the compressed earth bricks (CEBs) in order to reduce the footprint of the coal industry. For this purpose, three soils of the Marrakesh region were studied in terms of their chemical composition, and their thermal and mechanical behavior. Then, the selected soil was mixed with different amounts of CA (10%, 15%, and 20% by weight) and compressed in a Brava machine to produce (CEBs). A significant drop in the specific weight of our CEBs was registered with the increase of CA percentage. Besides, the compressive strength showed a linear drop with the increase of (CA) percentages. In fact, for bricks with 20% of CA, the decrease in compressive strength reaches 32.95% in respect to the reference bricks. Moreover, CA showed interesting gain in thermal conductivity reaching 60% while the diminution in compressive strength was still acceptable according to norms in the state of the art. Thereby, we can say that using CA in earth bricks can, with the suitable architecture, contribute not only to reduce the building charges, but also to provide a good thermal comfort without increasing the thickness of the walls