Search results for "Structural Engineering"

Energy-Saving Mechatronic System for Fatigue Tests of Materials under Variable-Amplitude Proportional Bending and Torsion

2010

The paper presents structure and principles of operation of the fatigue test stand for specimens subjected to polyharmonic proportional bending and torsion. The stand is equipped with a digital control system based on data acquisition board Daqboard/2000 and LabVIEW environment. The history of polyharmonic loading is a sum of four harmonic components of various amplitudes, frequencies and phases adjusted by means of four rotating disks with unbalanced masses of the inertial vibrator. Application of a computer with the software elaborated by the authors and the control system enables determination of fatigue characteristics of the material under constant or variable amplitude bending, torsio…

Characterisation and radiolysis of modified lithium orthosilicate pebbles with noble metal impurities

2017

Modified lithium orthosilicate (Li4SiO4) pebbles with additions of titanium dioxide (TiO2) are suggested as an alternative tritium breeding ceramic for the European solid breeder test blanket module. The noble metals – platinum (Pt), gold (Au) and rhodium (Rh), can be introduced into the modified Li4SiO4 pebbles during the melt-based process, due to the corrosion of Pt-Rh and Pt-Au alloy crucible components. In this study, the surface microstructure, chemical and phase composition of the modified Li4SiO4 pebbles with different contents of the noble metals was analysed. The influence of the noble metals on the radiolysis was evaluated after irradiation with accelerated electrons (E = 5 MeV),…

A cohesive interface model for the structural mechanics of block masonry

1997

Viscoelastic material models for more accurate polyethylene wear estimation

2018

Wear debris from ultra-high-molecular-weight polyethylene components used for joint replacement prostheses can cause significant clinical complications, and it is essential to be able to predict implant wear accurately in vitro to prevent unsafe implant designs continuing to clinical trials. The established method to predict wear is simulator testing, but the significant equipment costs, experimental time and equipment availability can be prohibitive. It is possible to predict implant wear using finite element methods, though those reported in the literature simplify the material behaviour of polyethylene and typically use linear or elastoplastic material models. Such models cannot represe…

Efficiency of Stress-Strain Models of Confined Concrete With and Without Steel Jacketing to Reproduce Experimental Results

2016

The improvement and the capacity assessment of existing buildings has become the main topic of the last years so that different studies can be found devoted to damaged structures or structures not having a capacity compatible with the safety levels of the actual codes. Reinforced concrete framed structure buildings represent a conspicuous rate of the existing constructions so many efforts are addressed to them. Referring to this type of buildings, a good prediction of strength and deformation capacity requests models able to interpret the constitutive law of concrete confined by internal reinforcement or by eventual external reinforcement applied to increase capacity of cross-sections. Cons…

Analysis of stress concentration during tension of round pultruded composite rods

2008

The stress state in a solid round transversely isotropic rod loaded with balanced shear stresses on a part of its lateral surface is considered. The change in gripping conditions is simulated by varying the distribution of statically equivalent shear stresses. The solution for the stress state was obtained using exact equations of linear theory of elasticity of anisotropic body. An analysis of the distribution of longitudinal and hoop stresses showed that at the grip edges a very high stress concentration is possible, which depends on the radius of the tensioned rod and the distribution of shear stresses on the gripped surface. At the grip edges, the longitudinal and hoop stresses tend to i…

Effects of natural fibres reinforcement in lime plasters (kenaf and sisal vs. Polypropylene)

2014

Nowadays the tendency to realize environment-friendly products is becoming more widespread to ensure sustainable and smart development. The synthetic fibres, frequently used, are harmful to the environment because they are non-degradable and non-renewable. Their use has resulted in an increase of oil consumption. Therefore, the possibility of replacing them with natural fibres becomes increasingly concrete confirmed by the researches and investigations carried out. In this work three lime based plasters were prepared and analysed to evaluate the influence on their performance of different fibres used as reinforcement. In particular each plaster was realised by adding to the mortar the same …

Geometric characterization and simulation of planar layered elastomeric fibrous biomaterials

2015

An important class of biomaterials is composed of layered networks of elastomeric fibers. While there is a growing interest in modeling and simulation of the mechanical response of these biomaterials, a theoretical foundation for such simulations has yet to be firmly established. The present work addresses this issue in two ways. First, using methods of geometric probability we develop theoretical estimates for the linear and areal fiber intersection densities for two-dimensional fibrous networks. These are expressed in terms of the fiber density and orientation distribution function, both of which are relatively easy to measure properties. Secondly, we develop a random walk algorithm for g…

Modeling of ITER TF cooling system through 2D thermal analyses and enthalpy balance

2017

Abstract The winding pack of the ITER Toroidal Field (TF) coils is composed of 134 turns of Nb3Sn Cable in Conduit Conductor (CICCs) wound in 7 double pancakes and cooled by supercritical helium (He) at cryogenic temperature. The cooling of the Stainless Steel (SS) case supporting the winding pack is guaranteed by He circulation in 74 parallel channels. A 2D approach to compute the temperature distribution in the ITER TF winding pack is here proposed. The TF is divided in 32 poloidal segments, for each segment the corresponding 2D model is built and a thermal analysis is performed applying the corresponding nuclear heating computed with MCNP code considering the latest design updates, such …

Stress field model for strengthening of shear-flexure critical RC beams

2017

A model for the design of shear-flexure critical reinforced concrete elements strengthened with fiber-reinforced polymer (FRP) sheets and plates is presented. The model is based on the stress field approach and the equilibrium method and accounts for the different failure modes of FRP, focusing on the debonding of the FRP from the concrete surface. The efficiency of the model in the strength assessment of beams reinforced with FRP by the prediction of the shear-flexure capacity is checked by corroborating the results of several experimental tests found in the literature. Moreover, the presented model's capacity to reproduce experimental behavior is compared with the formulations suggested b…