Search results for "engineering.material"
showing 10 items of 2352 documents
A Comparative Analysis of the Machined Surfaces Quality of an Aluminum Alloy According to the Cutting Speed and Cutting Depth Variations
2019
The milling operations are a topical and especially future-oriented methods. The purpose of this scientific paper is to carry out an experimental research referring to the end-milling process of the 7136 aluminum alloy. This paper is a continuation of the own research activity carried out so far, within a company with the field of activity in the aerospace industry. The main objective is a comparative analysis which was carried out on the surface quality - machined on various cutting regimes. The cutting process parameters used in the end-milling process are: the cutting speed, the feed per tooth and the cutting depth. The obtained results of the surface roughness’s were measured longitudin…
Effect of Cold Working and Ring Indentation on Fatigue Life of Aluminum Alloy Specimens
2013
The article deals with the fatigue life of plates with hole made of aluminum alloy. Specifically, the combined effect of cold working expansion and ring indentation on improved fatigue life performance was investigated. Multiple fatigue tests were performed to determine the cycles to failure and the corresponding W¨ ohler diagram. Experimental results were compared with those of nontreated specimens. The conclusion was that cold working expansion and indentation create a delay on crack formation and fatigue failure.
Computer modelling of WGM microresonators with a zinc oxide nanolayer using COMSOL multiphysics software
2021
Whispering gallery mode resonators (WGMRs) are small axial symmetrical structures from transparent material, that can exceptionally well confine light within, thus making them ideal for studying light-matter interactions and using them as sensors. Various WGMR designs can be simulated using COMSOL Multiphysics. Sometimes an extra layer is coated on the surface of the resonator for achieving desirable effects. The extra layer changes quality factor of the resonator and ads extra modes for some frequencies. Different methods and studies are used for the exploration of this topic such as changing the thickness of the coating and using random functions to describe the roughness of the surface, …
Acoustic vibrations of embedded spherical nanoparticles
2005
Abstract A solid-matrix-embedded spherical nanoparticle has acoustic vibrational frequencies which are shifted and damped relative to modes of a free sphere. Not only the longitudinal plane wave acoustic impedances, but also the Poisson ratios of nanoparticle and matrix are important in determining the Q-factor of the “breathing” mode, for which frequencies and Q-factors with different material combinations are presented. High matrix sound speed (e.g. silica, titania, alumina, diamond) increases Q.
Criteria of multiaxial random fatigue based on stress, strain and energy parameters of damage in the critical plane
2005
In this paper generalized criteria of multiaxial random fatigue based on stress, strain and strain energy density parameters in the critical plane have been discussed. The proposed criteria reduce multiaxial state of stress to the equivalent uniaxial tension–compression or alternating bending. Relations between the coefficients occurring in the considered criteria have been derived. Thus, it is possible to take into account fatigue properties of materials under simple loading states during determination of the multiaxial fatigue life. Presented models have successfully correlated fatigue lives of cast iron GGG40 and steel 18G2A specimens under constant amplitude in-phase and out-of-phase lo…
Thermal imaging in artificial nonlinear media
1997
A method has been developed to determine the temperature distribution of ferroelectric surfaces and volumes. Based on the nonlinear optical effect of second harmonic generation (SHG) in highly nonlinear ferroelectric coating, demonstration of 2D thermosensing has been performed in the wide temperature range (77 K - 600 K). Physical concept of SHG thermal imaging, design of thermosensitive coating and experimental verification of the method has been discussed.
Plasmonic Silver Nanorod Sensitivity: Experiment and Simple Theoretical Treatment
2013
We compare the plasmonic sensitivity of silver and gold nanorods with similar resonance wavelengths by monitoring the plasmon resonance shift of single noble metal nanorods upon changing the environment from water to sucrose solution. We find that silver nanorods have 1.2 to 2 times higher sensitivity than gold in good agreement with simulations based on the boundary-elements-method (BEM). To exclude the effect of particle volume on sensitivity, we test gold rods with increasing particle width at a given resonance wavelength. Using the Drude-model of optical properties of metal together with the quasi-static approximation (QSA) for localized surface plas-mons, we show that the dominant cont…
Whispering gallery mode resonators coated with Au nanoparticles
2019
Whispering gallery mode resonators (WGMRs) are very interesting for sensing because a resonance shift could be caused by any perturbation of the surrounding environment. Additionally such a resonator is coated with nanomaterials to tailor and enhance the sensitivity for a specific purpose. WGMR were fabricated using standard telecommunication fiber and a hydrogen flame, characterized using the scan method to obtain the quality factors and then coated with gold nanoparticles (Au NPs) using dip coating method and characterized again for comparison. Au NPs were chosen because their positive impact on microresonator sensitivity has been mentioned before and the surface can later be functionaliz…
Spark Plasma Sintering tool design for preparing alumina-based Functionally Graded Materials
2016
Abstract A way to produce Functionally Graded Materials (FGM) is by means of Spark Plasma Sintering (SPS) and specifically designated tools. These new tools permit a current density modulation and therefore a temperature variation along the z-axis. The key feature relies on a varying die section. FEM modelling has given the suitable range of die dimensions between the top and the bottom to obtain a given temperature gradient (around 300 °C) out of roughly a 15 mm height. Experiments conducted in different configurations (with or without samples) and the measurement of the associated thermal gradient led to improvements of the mould (in particular the introduction of a counter-piston). By th…
Anodic Electro Deposition of CeO2 and Co-Doped CeO2 Thin Films
2013
CeO2 and Co containing CeO2 thin films were deposited on indium tin oxide and stainless steel by anodic electrodeposition. Scanning electron microscopy showed that the films are flat and show globular morphology and cracks resulting from volume shrinking. According to XRD and Raman Spectroscopy pure ceria layers are crystalline, while the presence of Co induces the formation of amorphous films. The good adhesion and the compactness allowed the photoelectrochemical characterization of the films. A band gap value of 2.9 eV was estimated for CeO2, while slightly higher values (̃3.0 eV) were estimated for Co containing films. A mechanism for ceria anodic electrodeposition is proposed and discus…