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Online since: September 2008
Authors: Andrea E. del Grosso
Smart technologies are not limited to provide sensing and actuation devices but also include innovative materials,
able to provide built-in sensing and actuation functions and properties like selfhealing or energy harvesting capabilities.
These fluids, that are already available on the market [9,10], are able to modify their rheological properties (viscosity) under an applied electrical or magnetic field.
The sensing elements under consideration for integration into textiles include optical fibers and sensitive fibers, such as those characterized by piezoelectric properties.
In the mentioned study, it appeared that simple safety measures based on conventional partial safety factors for resistance and loads related to an acceptable probability of failure or on a reliability index, as implemented in current design practices, could not be adequate to cope with the generality of the situations encountered in smart structures.
Conventional structural reliability measures can still be applied, and in principle partial safety factors may be reduced for monitored structures only based upon a determination of probabilities for false positive/negative conclusions from the sensor data acquisition (DAQ) logic processing chain.
These fluids, that are already available on the market [9,10], are able to modify their rheological properties (viscosity) under an applied electrical or magnetic field.
The sensing elements under consideration for integration into textiles include optical fibers and sensitive fibers, such as those characterized by piezoelectric properties.
In the mentioned study, it appeared that simple safety measures based on conventional partial safety factors for resistance and loads related to an acceptable probability of failure or on a reliability index, as implemented in current design practices, could not be adequate to cope with the generality of the situations encountered in smart structures.
Conventional structural reliability measures can still be applied, and in principle partial safety factors may be reduced for monitored structures only based upon a determination of probabilities for false positive/negative conclusions from the sensor data acquisition (DAQ) logic processing chain.
Online since: January 2016
Authors: Khalid M. Saqr, Ahmed el Gibaly, Omar Diaa, Tamer Hassan, Omar A. El-Bassiouny, Ali I. Shehata
Saqr1,3,f*
[1] Mechanical Engineering Department, College of Engineering and Technology, Arab Academy for Science, Technology and Maritime Transport
P.O.
While the majority of research works assumes that a Newtonian viscosity model is sufficient to predict the aneurysmal hemodynamics [1-3], recent studies have shown that the non-Newtonian properties of the blood significantly affect aneurysmal hemodynamics [4-7].
The aneurysmal WSS is a main factor that affects the rapture of cerebral aneurysms [15].
Low WSS values on the aneurysm wall are known to be an important rupture risk factor, and severe gradients do contribute to the aneurysm growth via a pathological route.
Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine, 2011. 225(6): p. 597-609
While the majority of research works assumes that a Newtonian viscosity model is sufficient to predict the aneurysmal hemodynamics [1-3], recent studies have shown that the non-Newtonian properties of the blood significantly affect aneurysmal hemodynamics [4-7].
The aneurysmal WSS is a main factor that affects the rapture of cerebral aneurysms [15].
Low WSS values on the aneurysm wall are known to be an important rupture risk factor, and severe gradients do contribute to the aneurysm growth via a pathological route.
Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine, 2011. 225(6): p. 597-609
Online since: October 2006
Authors: Jung Hwa Hong, Young Hwan Park, Sang Ok Ko, Gon Khang, Soon Hyuck Lee
In
general, bone strain generated streaming potential is affected by viscosity, flow rate, interstitial
pressure distribution.
The interstitial fluid pressure generation characteristics in bone are functions of its poroelastic properties and boundary conditions.
The mostly important factor governing the interstitial fluid flow is the fluid boundary condition.
Becker: Generation of Electric Potentials by Bone in Response to Mechanical Stress Science Vol. 137 (1962), p. 1063-1064 [3] R.B.
Mow: Streaming Potential of Human Lumbar Annulus Fibrosus is Anisotropic and Affected by Disk Degeneration J.
The interstitial fluid pressure generation characteristics in bone are functions of its poroelastic properties and boundary conditions.
The mostly important factor governing the interstitial fluid flow is the fluid boundary condition.
Becker: Generation of Electric Potentials by Bone in Response to Mechanical Stress Science Vol. 137 (1962), p. 1063-1064 [3] R.B.
Mow: Streaming Potential of Human Lumbar Annulus Fibrosus is Anisotropic and Affected by Disk Degeneration J.
Online since: June 2011
Authors: Jun Wang, Chang Ming Fan, Jing Ming Fan
Flow Dynamic Simulation of Micro Abrasive Water Jet
Jingming Fan1,a, Changming Fan1,b and Jun Wang2,c
1School of Electromechanical Engineering, Guangdong University of Technology,
Guangzhou 510006, China
2 School of Mechanical and Manufacturing Engineering, The University of New South Wales,
Sydney, NSW 2052, Australia
ajmfan@gdut.edu.cn; bfanchm@gdut.edu.cn; cjun.wang@unsw.edu.au
Keywords: Micro abrasive water jet; Computation fluid dynamics (CFD) simulation; Impinging jet; Particle velocity
Abstract.
More competitive with micro EDM and laser cutting, MAWJ technology, which has the distinct advantages of no thermal distortion, no heat affected zones, no mechanical stress, high machining efficiency and small cutting force, offers potential for the micro processing of difficult-to-machining materials, especially if no thermal stress is allowed.
Kinetic energy of MAWJ plays a key factor in the cutting capacity, while it is mostly affected by impulsive velocity of the abrasives.
Optimization of nozzle size and geometry and the jet properties are essential to obtain a better cutting performance in MAWJ.
Furthermore, the particle trajectory agrees with the findings in literature that the turbulent dispersion is an important factor on the particle movement.
More competitive with micro EDM and laser cutting, MAWJ technology, which has the distinct advantages of no thermal distortion, no heat affected zones, no mechanical stress, high machining efficiency and small cutting force, offers potential for the micro processing of difficult-to-machining materials, especially if no thermal stress is allowed.
Kinetic energy of MAWJ plays a key factor in the cutting capacity, while it is mostly affected by impulsive velocity of the abrasives.
Optimization of nozzle size and geometry and the jet properties are essential to obtain a better cutting performance in MAWJ.
Furthermore, the particle trajectory agrees with the findings in literature that the turbulent dispersion is an important factor on the particle movement.
Online since: July 2022
Authors: Luca Corallo, Patricia Verleysen
It has been reported that the tension-compression asymmetry highly affects the results of deep drawing operations in terms of thickness reduction, earing profile and drawing force [2].
During high-speed forming operations, strain rate highly affects the forming properties of sheet metals [6], both in terms of material hardening and the related onset of strain localization [7].
The two procedures, cooled-down and slowed-down, are employed to verify if strain rate and thermal softening factors assessed for the RD are also valid for the tensile data obtained at different orientations, namely if there is any dependency between strain rate, temperature and material anisotropy.
Crystal Plasticity Based Modelling of the Strain Rate Dependent Mechanical Behaviour of Ti6Al4V.
Overview of Identification Methods of Mechanical Parameters Based on Full-field Measurements.
During high-speed forming operations, strain rate highly affects the forming properties of sheet metals [6], both in terms of material hardening and the related onset of strain localization [7].
The two procedures, cooled-down and slowed-down, are employed to verify if strain rate and thermal softening factors assessed for the RD are also valid for the tensile data obtained at different orientations, namely if there is any dependency between strain rate, temperature and material anisotropy.
Crystal Plasticity Based Modelling of the Strain Rate Dependent Mechanical Behaviour of Ti6Al4V.
Overview of Identification Methods of Mechanical Parameters Based on Full-field Measurements.
Online since: December 2006
Authors: Wei Sun, Xiang Zheng, Meng Nie, Xiao Yuan He
From the mechanical point of view there are a few typical elements that usually appear in
micro-mechanisms - membranes, beams, comb and flat springs.
The beams are also used to measure material properties of thin films, in particular Young's modulus and residual stress, in conjunction with the electrostatic pull-in technique.
The calibrated factor k is 0.45pixel/µm.
Vibrating shape, Q-factor and resonant frequency of the folded beams are investigated respectively.
Q-factor of the mechanical vibrating system affects the sensitivity and resolution of MEMS gyroscope sensor.
The beams are also used to measure material properties of thin films, in particular Young's modulus and residual stress, in conjunction with the electrostatic pull-in technique.
The calibrated factor k is 0.45pixel/µm.
Vibrating shape, Q-factor and resonant frequency of the folded beams are investigated respectively.
Q-factor of the mechanical vibrating system affects the sensitivity and resolution of MEMS gyroscope sensor.
Online since: February 2020
Authors: K.Chandra Shekar, G.Gowtham Reddy, S. Deva Prasad, B. Singaravel
Dielectric properties are categorized into electro chemical properties and electro physical properties.
In EDM process, ionization and deionization depends on electro physical properties like kinematic viscosity, pour point, fire point, flash point, thermal conductivity and specific heat and electro chemical properties such as breakdown voltage, dielectric constant, dielectric dissipation factor, interfacial tension, water content, acidity value and dissolved gas analysis of dielectric fluids [6, 7].
In their investigation, different edible oils (Canola, Sunflower, Soyabean and Olive) and its electro-chemical properties (dielectric breakdown voltage, dissipation factor, interfacial tension and acidity number) were analyzed.
Table 1 shows the various properties of conventional dielectric and vegetable oils.
Surface roughness of the component influences the tribological properties.
In EDM process, ionization and deionization depends on electro physical properties like kinematic viscosity, pour point, fire point, flash point, thermal conductivity and specific heat and electro chemical properties such as breakdown voltage, dielectric constant, dielectric dissipation factor, interfacial tension, water content, acidity value and dissolved gas analysis of dielectric fluids [6, 7].
In their investigation, different edible oils (Canola, Sunflower, Soyabean and Olive) and its electro-chemical properties (dielectric breakdown voltage, dissipation factor, interfacial tension and acidity number) were analyzed.
Table 1 shows the various properties of conventional dielectric and vegetable oils.
Surface roughness of the component influences the tribological properties.
Online since: January 2013
Authors: Qing Hua Qin, Bing Hui Zhao, Chuan Yong Qu
During its entire lifetime, bone is able to adapt its internal microstructure and, subsequently, mechanical properties to the varying mechanical and physiological environments in a process which is commonly known as bone remodeling [1].
A BMU in which osteoclasts and osteoblasts workin sequence to absorb dead bone and generate new bone. [2] As mentioned above, bone tissue is able to adapt its internal microstructure and mechanical properties to the external (mechanical and electrical environments [5-7], electromagnetic field [8,9], etc) and internal factor (microdamage [10]).
Firstly, the initial material properties are assumed and boundary condition loading is applied.
Finally, the bone remodeling enters the formation period from day 30 to day 110, in which the mechanical properties and microstructure gradually restore to the initial situation with the new bone deposit.
Human physiology damage-repair cycle and damage factor [28] is considered in the algorithm too.
A BMU in which osteoclasts and osteoblasts workin sequence to absorb dead bone and generate new bone. [2] As mentioned above, bone tissue is able to adapt its internal microstructure and mechanical properties to the external (mechanical and electrical environments [5-7], electromagnetic field [8,9], etc) and internal factor (microdamage [10]).
Firstly, the initial material properties are assumed and boundary condition loading is applied.
Finally, the bone remodeling enters the formation period from day 30 to day 110, in which the mechanical properties and microstructure gradually restore to the initial situation with the new bone deposit.
Human physiology damage-repair cycle and damage factor [28] is considered in the algorithm too.
Fabrication of Deep Tapered Perforation Using a Modified through-Mask Electrochemical Micromachining
Online since: September 2013
Authors: Zhen Bin Lv, Xiao Hui Bao, Shu Qing Wang, Si Qi Liu, Ping Mei Ming
Some materials with excellent mechanical properties and corrosion resistance, such as stainless steel, are regarded as the ideal selections for preparation of metal working screen, but they cannot be shaped using electrodeposition technique..
Through-mask electrochemical micromachining (Through-mask EMM), which can process any metal materials regardless of their mechanical properties, has been preferentially applied to fabricate micro-& meso-scale hole array because of its some unique merits, such as short process time, good surface finish, and better controllability and flexibility.
Although, during through-mask EMM, undercutting dissolution is generally inevitable due to the isotropic nature of metal removal process, desired hole contour with good surface can be obtained by taking into proper consideration of some key factors including mass transport, current distribution and design of mask artwork[2,3].
Like Model-1, the change in composite mask thickness caused by either insulation mask or inert metal mask affects only magnitude of current density at each point of the workpiece surface.
Although it is also found that a favorable distribution profile of current density can be observed if only inert metal mask is applied, current densities on the workpiece are too small to etch metal electrochemically, resulting in an extremely low machine rate and a bad machining accuracy.In view of other factors, including etching rate, machining accuracy, mass transfer and mask fabrication, 0.05mm thick inert metal mask and 0.05mm thick insulation mask with a wall side angle of 45o of composite masks are selected in this study.
Through-mask electrochemical micromachining (Through-mask EMM), which can process any metal materials regardless of their mechanical properties, has been preferentially applied to fabricate micro-& meso-scale hole array because of its some unique merits, such as short process time, good surface finish, and better controllability and flexibility.
Although, during through-mask EMM, undercutting dissolution is generally inevitable due to the isotropic nature of metal removal process, desired hole contour with good surface can be obtained by taking into proper consideration of some key factors including mass transport, current distribution and design of mask artwork[2,3].
Like Model-1, the change in composite mask thickness caused by either insulation mask or inert metal mask affects only magnitude of current density at each point of the workpiece surface.
Although it is also found that a favorable distribution profile of current density can be observed if only inert metal mask is applied, current densities on the workpiece are too small to etch metal electrochemically, resulting in an extremely low machine rate and a bad machining accuracy.In view of other factors, including etching rate, machining accuracy, mass transfer and mask fabrication, 0.05mm thick inert metal mask and 0.05mm thick insulation mask with a wall side angle of 45o of composite masks are selected in this study.
Online since: February 2024
Authors: Pavlo Agraval, Anna Vodopyanova, Liya Dreval, Mikhail Turchanin
Introduction
Metallic glasses are attractive for modern industry due to a set of unique properties, such as mechanical, magnetic, chemical, etc.
At present, information about multicomponent amorphous alloys is available mainly for individual point compositions in the form of data on conditions of production, structure, mechanical and some other physical properties.
It was determined the presence of a sufficient content of metals that are electron acceptors and donors is a chemical factor that affects the thermodynamic stability of melts and determines their glass-forming ability.
Turchanin, Thermodynamic properties of iron melts with titanium, zirconium, and hafnium, Powder Metall.
Goto, Electron transport properties of ternary metallic glasses (Ni33Zr67)1-xXx (X= Ti, V, Cr, Mn, Fe, Co and Cu): the magnetic effect on the electron transport properties, J.
At present, information about multicomponent amorphous alloys is available mainly for individual point compositions in the form of data on conditions of production, structure, mechanical and some other physical properties.
It was determined the presence of a sufficient content of metals that are electron acceptors and donors is a chemical factor that affects the thermodynamic stability of melts and determines their glass-forming ability.
Turchanin, Thermodynamic properties of iron melts with titanium, zirconium, and hafnium, Powder Metall.
Goto, Electron transport properties of ternary metallic glasses (Ni33Zr67)1-xXx (X= Ti, V, Cr, Mn, Fe, Co and Cu): the magnetic effect on the electron transport properties, J.