Search results for "Structural engineering"
showing 10 items of 1998 documents
Preliminary structural assessment of the HELIAS 5-B breeding blanket
2019
Abstract The European Roadmap to the realisation of fusion energy, carried out by the EUROfusion consortium, considers the stellarator concept as a possible long-term alternative to a tokamak fusion power plant. To this purpose a pivotal issue is the design of a HELIcal-axis Advanced Stellarator (HELIAS) machine equipped with a tritium Breeding Blanket (BB), considering the achievements and the design experience acquired in the pre-conceptual design phase of the tokamak DEMO BB. Therefore, within the framework of EUROfusion Work Package S2 R&D activity, a research campaign has been launched at KIT. The scope of the research has been the determination of a preliminary BB segmentation scheme …
Nonlinear finite element analysis of no-tension masonry structures
1995
A numerical approach for structural analysis of masonry walls in plane stress conditions is presented. The assumption of a perfectly no-tension material (NTM) constitutive model, whose relevant equations are in the form of classical rate-independent associated flow laws of elastoplastic material, allows one to adopt numerical procedures commonly used in computational plasticity. An accuracy analysis on the integration algorithm employed in the solution of constitutive relations has been carried out. The results obtained for some relevant case-studies and their comparison with data, available in the literature show the effectiveness of the proposed method.
Debonding failure mechanisms in prestressed CFRP/epoxy/concrete connections
2014
Abstract This paper presents an investigation on the failure mode in prestress force-release tests of CFRP strips bonded to concrete substrates. Background of the study is the gradient anchorage technique. Firstly, experimental test series are presented. It is shown that considerable differences in failure mechanisms between lap-shear and the before mentioned release tests exist. The study reveals a strong Mode I-influence in the debonding process, compared to a Mode II for lap-shear tests. Secondly, FE simulations with a commercially available software are introduced. It is demonstrated that delamination in a force-release test occurs by a mixed-mode failure over the strip width.
Experimental Studies Regarding Mechanical Behaviour of Textile Reinforcements Laminated Composite Materials
2013
The aim of this paper is to determine the mechanical properties of textile reinforcements laminated composite material and to establish the influence of thickness about these properties. The composite material used for this is a laminated sheet of HGW 2082. In order to study the mechanical behaviour of these kinds of materials we select two experimental tests: uniaxial test and bending test. For the uniaxial test we have measured the maximum load, the maximum extension, the maximum tensile stress and the maximum tensile strain. Also, using an optical extensometer we measured the major and the minor strains. For the bending test we measured the maximum load and the maximum bending deflection…
Strength prediction of a triaxially braided composite
2011
The architecture of textile reinforcement affects the deformation and failure behavior of the textile reinforced composites. This paper presents an approximate method that incorporates the in-plane periodic meso structure of the textile composite in finite element models. In this approach, the representative unit cell (RUC) of a textile composite is divided into sub-cells. Instead of obtaining a homogeneous equivalent, these sub-cells are idealized and represented with laminates of different layups using shell elements. In this way, an RUC can be constructed with a small number of elements. This method holds the promise of creating a textile composite FE model with an improved accuracy with…
Architectural technologies for life environment: Spent coffee ground reuse in lime-based mortars. A preliminary assessment for innovative green therm…
2022
Spent coffee ground, the residue obtained from the brewing process, is the primary unavoidable (inedible) waste from the coffee consumption. As coffee production and beverage consumption are increasing worldwide, a more sustainable waste management is required since the usual disposal in landfill is a liability to both humans and the environment. This paper is aimed at showing a possible alternative reuse of coffee ground wastes in novel green building materials intended for thermo-plastering applications in construction, in a circular economy context. Coffee waste was used in various percentages (up to 17.5%) to assess the engineering performance of the produced bio-composite mortars. The …
Nonstationary flow surface theory for modeling the viscoplastic behaviors of soils
2016
Abstract This paper presents a three-dimensional elastic viscoplastic model that can describe the time-dependent behaviors of soft clays. The constitutive model is formulated based on the nonstationary flow surface theory and incorporates new developments, including (i) an improved definition of the nonstationary flow surface that is capable of capturing the stress–strain behaviors under different loading paths, (ii) a unique stress–strain—viscoplastic-strain-rate equation that is able to explicitly describe the nonstationary flow surface, and (iii) a final stable state concept that identifies the final equilibrium state at the end of creep and stress relaxation, which is also used to simpl…
Criteria for validity of thermodynamic equations from non-equilibrium molecular dynamics simulations
2008
Abstract The assumption of local equilibrium is validated in four different systems where heat and mass are transported. Mass fluxes up to 13 kmol / m 2 s and temperature gradients up to 10 12 K / m were used. A two-component mixture, two vapor–liquid interfaces, a chemical reaction in a temperature gradient and gas adsorbed in zeolite were studied using non-equilibrium molecular dynamics simulations. In all cases, we verified that thermodynamic variables obeyed normal thermodynamic relations, with an accuracy better than 5%. The heat and mass fluxes, and the reaction rate were linearly related to the driving forces. Onsager's reciprocal relations were validated for two systems. Equipartiti…
The role of nanoparticles in decreased washout of underwater concrete
2019
Abstract The paper presents research results of the influence of SiO2 nanoparticles on the washout of underwater concrete and hardened concrete. Based on infrared spectroscopy (FTIR) and thermogravimetric (TGA) analyses of the applied anti-washout admixture (AWA), its chemical structure was determined. A beneficial effect of SiO2 nanoparticles on the reduction of the mix washout was demonstrated and the most probable reason for that phenomenon was given, taking into account the AWA chemical structure and its behaviour in the concrete mix environment. It was found that a dosing method of AWA and nanoparticles to the concrete influenced the washout.
Preliminary thermal optimization and investigation of the overall structural behaviour of the EU-DEMO water-cooled lead lithium left outboard blanket…
2022
The conceptual design phase of the EU-DEMO reactor has been recently launched, with the aim of evolving the DEMO pre-conceptual layout towards a more robust and articulated geometric configuration able to cope with most of the design requirements and to show further margins for the passing of the current potential show-stoppers. Hence, the achievement of the conceptual design of the Water-Cooled Lead Lithium Breeding Blanket (WCLL BB) is one of the milestones the EUROfusion consortium aims to achieve in the close future. To this purpose, within the framework of the research activities promoted by EUROfusion, a research campaign has been launched at the University of Palermo, in close cooper…