scholarly journals Relaxation of Residual Stresses in Brush-Plated Gold and Silver Coatings on Copper and on Brass Substrates

2014 ◽  
Vol 996 ◽  
pp. 866-871
Author(s):  
Harri Lille ◽  
Jakub Kõo ◽  
Alexander Ryabchikov ◽  
Renno Reitsnik ◽  
Fjodor Sergejev ◽  
...  
Keyword(s):  
Relaxation Time ◽  
Residual Stresses ◽  
Surface Structure ◽  
Cross Section ◽  
Instrumented Indentation ◽  
Open Ring ◽  
Linear Fractional Function ◽  
Thin Walled ◽  
Fractional Function ◽  
Over Time

The investigated brush-plated gold and silver coatings are used for repairing the commutators of generators and sliding contacts. Tensile residual stresses generated in the plated coatings were determined by the curvature method and by instrumented indentation testing of a thin-walled open ring substrate, as described in our earlier papers. These stresses relax over time and their dependence on relaxation time was approximated by a linear-fractional function. The Young ́s modulus and nanohardness of the coatings were determined. The surface structure and cross section of the coated substrates were studied.

Comparative Analysis of Residual Stresses Determined by Various Methods in Brush-Plated Hard Gold and Silver Coatings

2014 ◽  
Vol 604 ◽  
pp. 8-11
Author(s):  
Harri Lille ◽  
Jakub Kõo ◽  
Alexander Ryabchikov ◽  
Renno Reitsnik ◽  
Fjodor Sergejev ◽  
...  
Keyword(s):  
Relaxation Time ◽  
Comparative Analysis ◽  
Residual Stresses ◽  
Cross Section ◽  
Instrumented Indentation ◽  
Morphology And Structure ◽  
Linear Fractional Function ◽  
Thin Walled ◽  
Fractional Function ◽  
Over Time

The investigated brush-plated silver and gold coatings are used for refining the surface properties of electric apparatuses. Tensile residual stresses generated in the plated coatings were determined with a thin-walled ring substrate using the curvature and instrumented indentation techniques. These stresses relax over time; the dependence of relaxation time was approximated by a linear-fractional function. The modulus of elasticity and the nanohardness of the coatings were determined by nanoindentation. The surface morphology and structure in cross-section of the coated substrates are presented.

Investigation of Residual Stresses and some Elastic Properties of Brush-Plated Gold and Silver Galvanic Coatings

2012 ◽  
Vol 527 ◽  
pp. 125-130 ◽  
Author(s):  
Harri Lille ◽  
Jakub Kõo ◽  
Alexander Ryabchikov ◽  
Renno Reitsnik ◽  
Renno Veinthal ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Residual Stresses ◽  
Experimental Parameter ◽  
Instrumented Indentation ◽  
X Ray Diffraction ◽  
X Ray ◽  
Thin Walled ◽  
Copper Ring ◽  
Scanning Electron

Nickel-hardened gold and silver coatings were brush-plated from a commercial SIFCO Dalic Solution (Gold Hard Alloy), Code SPS 5370, and Silver Hard Heavy Build, Code SPS 3080, on unclosed thin-walled copper ring substrates. To determine residual stresses, the conventional curvature method (common among the electrodeposition methods) was applied, where the substrate was coated with certain thickness and then the slit increment (bending deflection) of the substrate was measured as an experimental parameter. Residual stresses on gold coatings were also determined by X-ray diffraction (XRD) based on the sin2 method. The values of residual stresses determined by the curvature method and by the XRD technique were comparable. Relaxation of residual stresses was observed. An equation for approximation of the change of residual stresses was applied assuming that the dependence of residual stresses on relaxation time is linear-fractional. The surface morphology and microstructure of the coatings was studied by means of scanning electron microscopy (SEM). The magnitudes of the modulus of elasticity and of the nanohardness of the coatings were obtained by instrumented indentation.

A comparative study of two experimental techniques for the measurement of residual stresses in circular rods and tubes of perspex

1989 ◽  
Vol 24 (3) ◽  
pp. 163-171
Author(s):  
R K Mittal ◽  
I A Khan
Keyword(s):  
Residual Stresses ◽  
Cross Section ◽  
The Other ◽  
Experimental Techniques ◽  
Entire Cross Section ◽  
Sum Rule ◽  
Thin Walled ◽  
Removal Technique ◽  
Non Destructive ◽  
Distribution Of Stresses

Two experimental techniques have been used to measure residual stresses in circular rods and tubes of perspex, i.e., polymethyl methacrylate (PMMA). The first technique, based on photoelasticity, is non-destructive and easy to apply. It gives distribution of stresses over the entire cross-section. The analysis of this technique has been improved to relax some restrictions. The other technique is the layer removal technique. A serious drawback of this technique is that it fails to give the distribution of stresses over the entire cross-section and its accuracy for thin walled tubes is doubtful. A simplification of this technique is possible if the kinematic assumption introduced by Nishimura is replaced by one using the sum rule of stresses.

First and Second Order Elastoplastic Analyses of Thin-Walled Metal Members using Generalized Beam Theory

2018 ◽  
Author(s):  
Miguel Abambres
Keyword(s):  
Finite Element ◽  
Stainless Steel ◽  
Cross Section ◽  
Beam Theory ◽  
Second Order ◽  
Flow Rule ◽  
Non Linear ◽  
Thin Walled ◽  
Shell Finite Element ◽  
Generalized Beam Theory

Original Generalized Beam Theory (GBT) formulations for elastoplastic first and second order (postbuckling) analyses of thin-walled members are proposed, based on the J2 theory with associated flow rule, and valid for (i) arbitrary residual stress and geometric imperfection distributions, (ii) non-linear isotropic materials (e.g., carbon/stainless steel), and (iii) arbitrary deformation patterns (e.g., global, local, distortional, shear). The cross-section analysis is based on the formulation by Silva (2013), but adopts five types of nodal degrees of freedom (d.o.f.) – one of them (warping rotation) is an innovation of present work and allows the use of cubic polynomials (instead of linear functions) to approximate the warping profiles in each sub-plate. The formulations are validated by presenting various illustrative examples involving beams and columns characterized by several cross-section types (open, closed, (un) branched), materials (bi-linear or non-linear – e.g., stainless steel) and boundary conditions. The GBT results (equilibrium paths, stress/displacement distributions and collapse mechanisms) are validated by comparison with those obtained from shell finite element analyses. It is observed that the results are globally very similar with only 9% and 21% (1st and 2nd order) of the d.o.f. numbers required by the shell finite element models. Moreover, the GBT unique modal nature is highlighted by means of modal participation diagrams and amplitude functions, as well as analyses based on different deformation mode sets, providing an in-depth insight on the member behavioural mechanics in both elastic and inelastic regimes.

To the theory analysis of tightness of tank of pressure testing

2019 ◽  
Vol 5 (4) ◽  
pp. 129-142
Author(s):  
Vladislav Sh. Shagapov ◽  
Ismagilyan G. Khusainov ◽  
Emiliya V. Galiakbarova ◽  
Zulfya R. Khakimova
Keyword(s):  
Relaxation Time ◽  
Three Dimensional ◽  
Petroleum Products ◽  
Technical Condition ◽  
Excess Pressure ◽  
Soil Parameters ◽  
Theory Analysis ◽  
Pressure Testing ◽  
Tank Pressure ◽  
Over Time

This article studies the process of relaxation of the pressure in a tank with the damaged area of the wall after pressure-testing. The authors use different methods for the diagnosis of the technical condition of objects of petroleum products storage. Pressure testing is one of nondestructive methods. The rate of pressure decrease is characteristic of the system tightness. This article studies the cases of ground and underground location of the tank. Pressure testing involves excess pressure inside of a tank and observing its decrease. Over time, one can assess the integrity of the system. This has required creating mathematical models to account the filtration of the liquid depending on the location of the tank. The results include the analytical solution of the task and the formulas for describing the dependence of the relaxation time of pressure in the tank from the liquid and soil parameters, geometry of the tank, and the damaged portion of the wall. The two- and three-dimensional cases of liquids filtration for the case of underground location of the tank were considered. The results of some numerical calculations of the dependence of reduction time and the time of half-life pressure from the area of the damaged portion of the wall were shown. The obtained solutions allow assessing the extent of the damaged area by the pressure testing with known values of tank, liquid, and soil.

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