Abstract

The presentation is aimed to cover areas related to modeling of material behaviour using different numerical schemes. Special emphasis is laid on homogenization procedures and multi- scale approaches that include inelastic microstructural deformations and development of inter- face cracks. In detail the inelastic responses of polycrystals is investigated including induced anisotropy and nonlinear hardening. The necessary numerical procedures will be discussed and examples from different areas are introduced. 

Included in this presentation is the design of macroscopic constitutive equations with only few parameters that are obtained from homogenization of polycrystal assemblies. The results are validated at micro and macro scale by means of experiments. These include as well results from microstructural observation as from classical pullout tests. Typical and important industrial applications range from ceramic to ductile materials.

Abstract

Particle methods are those in which the problem is represented by a discrete number of particles. Each particle moves accordingly with its own mass and the external/internal forces applied on it. In this paper the Particle Finite Element Method based on finite element shape functions is used to solve the continuous fluid mechanics equations in the case of heterogeneous density. To evaluate the external applied forces to each particle, the incompressible Navier–Stokes equations are solved at each time step using a Lagrangian formulation. All the information in the fluid is transmitted via the particles. All kinds of density heterogeneous fluids and multiphase flows with internal interfaces including or not free-surfaces, breaking waves and fluid separations may be easily solved with this methodology. 

Abstract

Abstract

The most commonly used wall coverings are still, undoubtedly, plasters and renders, whether lime-based or cement-based, whether traditional and prepared in-situ or pre-dosed. In accordance with the available standards, the characterization of these mortars is made on laboratory test specimens, with dimensions, curing conditions and test procedures according to the prescribed. However, when applying these mortars to the real substrates, their behaviour will not be the same. After application of the mortar to the substrate, an interface will be formed, and the interactions that occur after the contact of the mortar, still in the plastic state, with the substrate will change over time due to the hydration kinetics and absorption of the substrate. It is very important to know the real behaviour of mortars after application, in order to ensure their durability. A research project is being developed to analyse the proper behaviour of mortars after application to the substrates. In order to characterize a mortar after application to a substrate, it is necessary to detach it. The introduction of a fiberglass grid in the mortarsubstrate interface makes the detachment easier. The purpose of this study is to determine if the placement of this grid will influence the characteristics of the applied mortar. For this, an experimental campaign was carried out, comparing the characteristics of two mortar formulations, applied to different types of substrate (without introduction of the fiberglass grid), with the characteristics of these mortars applied to the same substrates, but with the introduction of a fiberglass grid at the interface mortar-substrate. In this paper, we present the results obtained for some of the physical and mechanical characteristics of cement and hydraulic lime mortars.

Abstract

In the present investigation, double cantilever beam (DCB) specimens manufactured using 3D printing (ALM) are investigated from an experimental point of view. The influence of the aspect ratio A/λ (A = amplitude, λ = wavelength) in the fracture toughness of non-conventional interfaces is analysed, specifically for trapezoidal profiles. The particular geometry of the interface herein considered corresponds to that with the greatest ratio A/λ using the current technical capabilities of ALM (Additive Layer Manufacturing) devices. In the first part of the investigation, a preliminary analysis comprising the assessment of the applicability of different materials, which are supported by the 3D printer (nailon and glass-fiber-reinforced polymer composites), are shown in the manufacturing section. This first part of the study is analysed from different points of view: from non-conventional interfaces manufacturing of different typologies (to determine the printer accuracy) to the actual specimen manufacturing. In the laboratory test section, the set-up of the test and specimens before the laboratory test are described. The fracture toughness of conventional and structured interfaces, in particular with trapezoidal profiles, are compared.

Abstract

The accurate modeling of moving boundaries and interfaces is a difficulty present in many situations in computational mechanics. In this paper we use a new approach, X-Mesh, to simulate with the finite element method the interaction between two immiscible fluids while keeping an accurate description of the interface without mesh regeneration. The method is validated with complex problems such as Rayleigh-Taylor instabilities, sloshing and dambreak. The quality of the results and the efficiency of the method show the potential of this approach to simulate such physical phenomena.