Search results for "Elastic Modulu"
showing 10 items of 189 documents
Multiple Surface Cracking and Debonding Failure for Thin Thermal Coatings
2019
Abstract A mechanical analysis of thin films of quasi-brittle materials used as thermal coatings for superalloy substrate is proposed. The study considers a bi-material element subjected to uniform tension formed by a thin layer of quasi-brittle material (typically a ceramic) bonded on an elastic substrate. The bounding between the coating film and the substrate is realized by a very thin primer which mechanically modeled as a zero thickness cohesive frictional interface. The analysis is developed by a non-linear finite element simulation in which, in order to consider damage size effects, a non-local isotropic damage model is adopted for the quasi-brittle coating. The results of the analys…
Hybrid Nanocomposite Coatings for Application in Construction Materials: Tribological Study
2009
The Nanocomposite group of AIDICO and the Nanomaterials Group of University of Valencia collaborate in the research of new organic-inorganic hybrid materials with application in construction products. Tribological properties and good thermal stability are some of the required specifications for such applications. Some hybrid coatings based on simultaneous formation of epoxy and silica networks are introduced in this work. Elastic modulus and hardness obtained from TDMA analyses and indentation techniques, together with thermal stability by TGA, are the main properties analysed in order to fulfil the requirements for construction coating applications. New routes for obtaining these coatings …
EVA-montmorillonite nanocomposites: effect of processing condition
2004
The aim of this study is to examine the effect of the compounding apparatus and of processing conditions on the properties of an organoclay-poly[ethylene-co-(vinyl acetate)] (EVA) nanocomposite. The filled materials were prepared using either a discontinuous batch mixer, a single screw extruder, a counter rotating intermeshing twin-screw compounder or a corotating intermeshing twin-screw extruder. The characterization of the obtained nanocomposites was performed by XRD, thermogravimetry, mechanical and rheological measurements. The study has shown the possibility of producing nanocomposites based on EVA and a commercial organoclay (Cloisite 15A) by several mixing equipments. In fact all the…
Starch Based Biodegradable Nanocomposites: Structure and Properties
2009
Plasticized starch (PS)/montmorillonite clay (MMT) nanocomposites were prepared by casting technique. Structural features, stress-strain characteristics and sorption properties were investigated. Upon introduction of rather small amounts of MMT, the PS parameters of the mechanical and barrier properties considerably improve. Tensile strength and elastic modulus of the materials examined decrease with increased moisture content, but the effect of reinforcement of PS with MMT nanoparticles remain intact.
Raman Monitoring of Strain Induced Effects in Mechanically Deposited Single Layer Graphene
2012
Graphene is a two dimensional building block for carbon allotropes of many other dimensionality and shows remarkable electronic and optical properties that attract enormous interest. In order to make graphene useful for real technology, a control of its electronic and mechanical properties is a must. In this respect, a crucial step for the use of graphene layers in device fabrication is the deposition onto suitable substrates, understanding the interaction with them. Micromechanical cleavage of graphite has been used to produce high-quality graphene sheets. The aim of this work is to study the strain effects induced in graphene by the deposition process using Raman spectroscopy and scanning…
Influence of formalin fixation on the biomechanical properties of human diaphyseal bone.
2010
Owing to the lack of fresh human bones, formalin-fixed specimens are frequently used in biomechanical testing. However, formalin fixation is assumed to affect the biomechanical properties of bone. The aim of this study was to compare axial and torsional stiffness and bone mineral density in fresh and embalmed human bones. The subtrochanteric regions of 12 pairs of fresh human femora were randomised into two groups for paired comparison. After bone mineral density measurement, one group was preserved in 4% formalin. After 6 weeks, bone mineral density was remeasured and each specimen underwent axial and torsional loading. The formalin group showed significant higher stiffness values for tors…
DIMENSIONAL STABILITY OF REINFORCED MATRICES.
1983
Particulate fillers are often used to improve the dimensional stability of polymeric items obtained through processing techniques such as injection molding, deep drawing, hot stamping, etc. In these operations the material undergoes large multiaxial deformations which result in molecular orientation and remain as frozen-in stresses during cooling of the material. Once the formed objects are exposed to sufficiently high temperatures, various degrees of spring-back take place and subsequent changes in shape and dimension occur (1).
Local ex-vivo evaluation of the biomechanical properties of the ascending aortic aneurysms
2019
Introduction Currently, surgical recommendations for aneurysm of the ascending aorta (AsAA) are based on the maximum diameter of the ascending aorta, but this factor is not reliable. Understanding the biomechanical properties of the aorta could lead to improve the prediction of the development of an AsAA. The aim of this study is to obtain the local patient specific elastic modulus distribution of the AsAA from a biaxial tensile test. Methods Pathologic ascending aortic tissue samples (n = 10) were obtained from patients undergoing elective surgical repair of AsAA ( Table 1 ). All the aortic wall samples were partitioned related to medial, posterior, lateral, and anterior quadrants. Each As…
The Role of Diffusion Accommodation and Phase Boundary Wetting in the Deformation Behaviour of Ultrafine Grained Sn-Pb Eutectic
2010
Mechanical properties, microstructure of the Sn–38wt. %Pb eutectic and the development of deformation - induced diffusion processes on interphase boundaries (IB) were investigated. Experiments were carried out both in deformed and annealed states of eutectic using micro- and nanoindentation, SEM, AFM and optical microscopy techniques. It was found that the deformation of the annealed alloy is localized at the Pb/Sn interphase boundaries and occurs by grain boundary sliding (GBS) accompanied by sintering micropore processes under the action of the capillary forces on the Pb/Sn IB. During severe plastic deformation of Sn-Pb eutectic phase transition in the Sn grain boundary occurs. This defor…
Field-induced ordering phenomena and non-local elastic compliance in two-dimensional colloidal crystals
2008
Ordering phenomena in colloidal dispersions exposed to external one-dimensional, periodic fields or under confinement are studied systematically by Monte Carlo computer simulations. Such systems are useful models for the study of monolayers on a substrate. We find that the interaction with a substrate potential completely changes the miscibility of a binary, hard disc mixture at low external field amplitudes. The underlying ordering mechanisms leading to this laser-induced de-mixing differ, depending on which components interact with the substrate potential. Generic effects of confinement on crystalline order in two dimensions are studied in a model system of point particles interacting via…