scholarly journals Modelling Machining-Induced Residual Stresses after Laser-Assisted Turning of Steels

2014 ◽  
Vol 996 ◽  
pp. 622-627 ◽  
Author(s):  
Mohamed N.A. Nasr ◽  
Mohamed Balbaa ◽  
Hassan Elgamal
Keyword(s):  
Plastic Deformation ◽  
Residual Stresses ◽  
Finite Element Modelling ◽  
Orthogonal Cutting ◽  
Thermal Softening ◽  
Heating Effect ◽  
Aisi 4340 Steel ◽  
Element Modelling ◽  
Laser Assisted Turning ◽  
Conventional Machining

The current study examines the effects of laser assistance on machining-induced residual stresses (RS), using finite element modelling, during turning of steels. Dry orthogonal cutting was modelled, along with the pre-heating effect of the laser beam. AISI 4340 steel was used in the current work. Laser-assisted machining (LAM) resulted in higher surface tensile RS compared to conventional machining, with more pronounced effects at lower feed rates. This is basically because the assisted material experienced higher plastic deformation, due to thermal softening, as well as higher temperatures, which are both attributed to the pre-heating effect of LAM.

Stress Measurement Using a Bilayer Metal-Ceramic Strip

1992 ◽  
Vol 264 ◽  
Author(s):  
Shukla Kapur ◽  
Philip L. Flaltz
Keyword(s):  
Finite Element ◽  
Thermal Expansion ◽  
Residual Stresses ◽  
Finite Element Modelling ◽  
Stress Measurement ◽  
Second Phase ◽  
Thermal Expansion Mismatch ◽  
Element Modelling ◽  
Metal Ceramic ◽  
Stress Asymmetry

AbstractResidual stresses that develop in metal/ceramic bonded systems due to thermal expansion mismatch have been calculated using finite element modelling and measured experimentally using a simple bilayer strip. Bending in the strip occurs during cooling due to the stress asymmetry. Residual stresses are calculated by measuring the deflection of the strip and the temperature at which the strip is flat. Various compositions of both copper and nickel pastes, with and without glass and other second phase additions were evaluated on glass-ceramic. The effects of further processes, e.g. thermal cycling, brazing and plating, are also reported in this work.

Finite Element Modelling of Stress-Induced Fracture in Ti-Si-N Films

2014 ◽  
Vol 553 ◽  
pp. 10-15
Author(s):  
E.A. Flores-Johnson ◽  
Lu Ming Shen ◽  
R.K. Annabattula ◽  
P.R. Onck ◽  
Yao Gen Shen ◽  
...  
Keyword(s):  
Thin Films ◽  
Residual Stresses ◽  
Finite Element Modelling ◽  
Nanocomposite Coating ◽  
Industrial Applications ◽  
Coating Films ◽  
Element Modelling ◽  
Mechanical And Physical Properties ◽  
Buckling Delamination ◽  
Sputter Deposited

Nanocomposite coating films have been increasingly used in industrial applications because of their unique mechanical and physical properties. Residual stresses generated during the growth of sputter-deposited thin films due to a strain mismatch between the film and the substrate may lead to significant failure problems. Large residual stresses may generate buckling, delamination and film fracture. Although buckles with cracks in thin films have been experimentally observed, their origins are still not well understood.

scholarly journals Predicting the Effects of Grain Size on Machining-Induced Residual Stresses in Steels

2014 ◽  
Vol 996 ◽  
pp. 634-639 ◽  
Author(s):  
Mohamed N.A. Nasr
Keyword(s):  
Grain Size ◽  
Yield Strength ◽  
Residual Stresses ◽  
Finite Element Modelling ◽  
Material Strength ◽  
Grain Size Effect ◽  
Inverse Relation ◽  
Lower Yield ◽  
Element Modelling ◽  
Lower Yield Strength

The current study examines the effect of grain size on machining-induced residual stresses (RS), during turning, using finite element modelling. Based on the well-known inverse relation between grain size and material strength, the grain size effect was simulated via changing the workpiece yield strength. This was also done at different strain hardening rates. The model was validated using four materials. Larger grain size (lower yield strength) resulted in higher surface tensile RS. This is attributed to the surface layer being subjected to higher compressive plastic deformation, as well as higher workpiece temperatures, which both contribute to higher tensile RS.

The Effect of Die Channel Angles and their Combination on Plastic Deformation of Pure Copper during Equal Channel Angular Pressing Using Finite Element Modelling

2019 ◽  
Vol 31 ◽  
pp. 63-69
Author(s):  
Malothu Ramulu ◽  
Arkanti Krishnaiah
Keyword(s):  
Plastic Deformation ◽  
Finite Element ◽  
Material Flow ◽  
Finite Element Modelling ◽  
Pure Copper ◽  
Plastic Deformations ◽  
Channel Angle ◽  
Element Modelling ◽  
Angular Pressing ◽  
Strain Inhomogeneity

It was investigated the effect of die channel angles and their combination on plastic deformation of pure copper during ECAP under friction and frictionless conditions using 2-D elastic-plastic finite element modelling. A sound knowledge obtained for the plastic deformation (material flow) and understood the relationships between plastic deformations. The modelling results suggested that strain inhomogeneity was lesser in channel angle 120o than channel angle 90o and pressing load as well as strain decrease with increasing die channel angle. The friction influence in case of combination of channel angles was negligible as compare to individual channel angles. The strain generation and distribution was more uniform in case of combination of channel angles as compare to individual channel angles.

Geometry Effects when Controlling Residual Stresses in Friction Stir Welds by Mechanical Tensioning

2006 ◽  
Vol 524-525 ◽  
pp. 71-76 ◽  
Author(s):  
David G. Richards ◽  
Philip B. Prangnell ◽  
Philip J. Withers ◽  
Stewart W. Williams ◽  
Andrew Wescott ◽  
...  
Keyword(s):  
Residual Stresses ◽  
Heat Input ◽  
Finite Element Modelling ◽  
Room Temperature ◽  
Welding Parameters ◽  
Fe Model ◽  
Element Modelling ◽  
Friction Stir ◽  
Low Sensitivity ◽  
Compressive Residual Stresses

Finite element modelling has proved to be an effective tool for the investigation of trends effected by changing welding conditions. This is especially important in mechanical tensioning of friction stir welds because of the large number of parameters involved. In this paper, an FE model is used to examine the effectiveness of the mechanical tensioning technique for controlling residual stresses in FSWs by the investigation of trends caused by changes to the welding parameters. Comparisons between different geometries, traverse speeds, and welding off-axis angle all produced consistent results, and showed that the peak stresses are most strongly influenced by both the local tensioning and heat input, and not by the more global welding conditions. The results also showed a progressive decrease in the residual stresses for increasing tensioning levels and, although affected by the heat input, a relatively low sensitivity to the welding variables. At tensioning levels greater than ~50% of the room temperature yield stress, tensile stresses were replaced by compressive residual stresses within the weld.

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