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Near-Surface Inhomogeneity of Electromechanical Fields
Published in Olha Hrytsyna, Vasyl Kondrat, Local Gradient Theory for Dielectrics, 2019
Thus, the surface tension in the half-space is determined by the surface stress σs and by characteristic length l*. Surface stress is proportional to the modified chemical potential μπ0′ in an infinite media, to the material parameter Kαρ, to the shear modulus G, and inversely proportional to the parameters dρ and K⌣≡K+43G−K2αρ2ρ0dρ.
Fundamentals of Treating the Interface
Published in Mukai Kusuhiro, Matsushita Taishi, Interfacial Physical Chemistry of High-Temperature Melts, 2019
Mukai Kusuhiro, Matsushita Taishi
In the previous sections, surface tension is discussed from the thermodynamic viewpoint. However, surface tension has a mechanical aspect, as the name implies, which is described later in Section 2.3. With respect to the surface tension as a force, the surface tension can be considered to be equal to the surface stress for liquid–gas, and liquid–liquid interfacial tension, as explained in the following section. However, in the case of the interface containing the solid phase, such as liquid–solid interface, the contribution of the stress must be considered. In this regard, let the relation between surface tension and surface stress be clarified.
Spray Systems
Published in Efstathios E. Michaelides, Clayton T. Crowe, John D. Schwarzkopf, Multiphase Flow Handbook, 2016
where U is the velocity is the density p is the pressure is the dynamic viscosity g is the gravitational acceleration Fs is the surface-tension force, which is a singular force active only at the location of the phase interface ere are three di erent approaches to model the surface-tension force in this context. e rst approach is the continuum surface force (CSF) method (Brackbill et al., 1992) de ned as Fs = skn f d(x - x f ) where is the mean curvature of the phase interface nf is its normal vector is the delta function concentrated on the phase interface e second approach is the continuous surface stress (CSS) model (Lafaurie et al., 1994, Guey er et al., 1999, Scardovelli and Zaleski, 1999) where the surface-tension force is expressed as the divergence of a surface-tension tensor: Fs = - ((I - n n )sd(x - x f )) (19.75) (19.74)
Influence of the microstructure on the subsurface and surface damage during lubricated rolling–sliding wear of sintered and sinterhardened 1.5%Mo–2%Cu–0.6%C steel: theoretical analysis and experimental investigation
Published in Powder Metallurgy, 2018
Samuel Tesfaye Mekonone, Wolfgang Pahl, Alberto Molinari
The surface stress may cause plastic deformation and, in turn, the formation of small surface cracks and/or densification. In both cases, the surface integrity and microgeometry are impaired. The surface plastic deformation occurs if the surface stress σsurf exceeds the resistance to plastic deformation σy, as by Eq. (11)The surface stress is defined by Eq. (12) [14]where is the coefficient of friction and Mr2 is the load bearing surface. But for elasto-hydrodynamic lubrication (EHL) contact condition, a continuous lubricant film could support contact load. Therefore, the effect of Mr2 can be ignored.
Hard milling of carburized and waterjet peened 18CrNiMo7-6 steel
Published in Machining Science and Technology, 2020
Yongtao Ma, Yongbin Zhang, Jiancheng Liu, Lanrong Liu, Junzhen Gong
The surface stress was measured using a high-energy X-ray residual stress analyzer. The wattage of the X-Ray is 1,200 W, the voltage is 30 KV and the current is 25 mA. A metal Cr anode X-ray tube for XRD was used. The residual stress deep in the surface was acquired by the electric erosion method. A HV-1000 micro-hardness tester was used to measure the hardness of the samples. The applied test force is 9.8 N, the speed of the test force is 0.05 mm/s and the test force retention time is 10 s. Each surface was tested for 5 points, and the final hardness was evaluated by an average of 5 points.
Cold rolling influence on residual stresses evolution in heat-treated AA7xxx T-section panels
Published in Materials and Manufacturing Processes, 2019
Ran. Pan, Jinghua. Zheng, Zipeng. Zhang, Jianguo. Lin
The X-ray diffraction technique is applied in determining the surface stress map about two stress components of specimens or components. Debye rings are used for characterizing the stress through the related change of εα due to diffraction data variation.