Numerical simulation of fatigue initiation life for notched specimens with gradient surface layer

2014 ◽  
Vol 44 (7) ◽  
pp. 737
Author(s):  
SiCong ZHAO ◽  
JiJia XIE ◽  
XiaoLei WU
Keyword(s):  
Numerical Simulation ◽  
Surface Layer ◽  
Notched Specimens ◽  
Fatigue Initiation ◽  
Gradient Surface

Simulation of crystallization of the melt modified by nanoscale particles during laser treatment of a metal surface

2021 ◽  
Vol 1 ◽  
pp. 5-14
Author(s):  
V.N. Popov ◽  
Keyword(s):  
Numerical Simulation ◽  
Surface Layer ◽  
Stokes Equations ◽  
Solid Phase ◽  
Laser Action ◽  
Heat Removal ◽  
Boussinesq Approximation ◽  
Grain Structure ◽  
Homogeneous Distribution ◽  
Dissolved Carbon

A 2D mathematical model is proposed for the modification of an iron-based alloy with refractory nanosized particles. Numerical simulation of the processes during the modification of the surface layer of the substrate metal using the energy of a laser pulse has been carried out. Within the framework of the proposed model, the processes of heating and melting of metal on a substrate covered with a layer of nanosized refractory particles penetrating into the molten metal, convective heat transfer in the melt, and solidification after the end of the pulse are considered. Metal melting is considered in the Stefan approximation, and when the melt is cooled, the model of heterogeneous nucleation and subsequent crystallization is used. The fluid flow is described by the Navier-Stokes equations in the Boussinesq approximation. The distribution of nanoparticles in the melt is modeled by moving markers. Based on the results of calculations, the mode of pulsed laser action is determined, in which a flow is formed for a homogeneous distribution of particles of the modifying substance in the presence of a surfactant in the metal. The volume of the solid phase formed around the nucleus determines the size of the grain structure in the solidified alloy. The liquidus temperature changes depending on the concentration of dissolved carbon in the melt. In the numerical simulation of the solidification of the surface layer of the metal, it was found that the conditions of nucleation and crystallization differ significantly in the volume of the melt. It is determined that the duration of nucleation in a supercooled melt is several tens of microseconds. The maximum number of crystallization centers occurs in areas where heat removal occurs most rapidly. With the growth of the solid phase in the melt and the release of the latent heat of crystallization, the value of supercooling decreases, the nucleation stops and the number of formed crystallization centers does not change further. The distribution of the dispersion of the crystal structure over the volume of the melted metal is estimated. It was found that as the melt cools, sequential-volume crystallization occurs.

Modeling Of Thermophysical Processes In The Case Of Surface Modifying Of Metal During Induction Treatment

2017 ◽  
Vol 12 (1) ◽  
pp. 91-96
Author(s):  
Vladimir Popov ◽  
Vladimir Shchukin
Keyword(s):  
Numerical Simulation ◽  
Electromagnetic Field ◽  
Surface Layer ◽  
Temperature Field ◽  
High Frequency ◽  
Induction Treatment ◽  
High Frequency Electromagnetic Field ◽  
Modes Of Processing

Process of modifying of the surface layer of metals under influence of high-frequency electromagnetic field was considered using numerical simulation. The temperature field and the size of modified region were determined at various modes of processing.

Using Nonlinear Contact Mechanics in Process of Tool Edge Movement on Deformable Body to Analysis of Cutting and Sliding Burnishing Processes

2014 ◽  
Vol 474 ◽  
pp. 339-344 ◽  
Author(s):  
Jaroslaw Chodor ◽  
Leon Kukielka
Keyword(s):  
Numerical Simulation ◽  
Mathematical Model ◽  
Surface Layer ◽  
Numerical Methods ◽  
Contact Problem ◽  
Deformable Body ◽  
Comprehensive Analysis ◽  
Tool Edge ◽  
Nonlinear Contact ◽  
Performance Conditions

Properties of the surface layer after cutting or sliding burnishing depend mainly on type of process and its performance conditions. For its comprehensive analysis is necessary to develop an adequate mathematical model and numerical methods of solving it. A common feature of both processes is moving the tool edge on elastic/visco-plastic workpiece. However, these processes are different i.e. the chip formation or chipless forming, therefore, different properties of surface layer depend mainly on: the geometry of the tool edge and its workpiece relative and depth of process. Therefore, this article is about the application of an incremental modelling and numerical solution of the contact problem between movable rigid and elastic/visco-plastic bodies developed in [ to the numerical simulation of physical process of moving a rigid tool on the workpiece.

Numerical Simulation of Residual Stresses Induced from Shot Peening with Finite Element Method

2013 ◽  
Vol 433-435 ◽  
pp. 1898-1901
Author(s):  
Li Juan Cao ◽  
Shou Ju Li ◽  
Zi Chang Shangguan
Keyword(s):  
Numerical Simulation ◽  
Finite Element Method ◽  
Residual Stress ◽  
Surface Layer ◽  
Residual Stresses ◽  
Shot Peening ◽  
Target Material ◽  
Residual Stress Field ◽  
State Of Stress ◽  
Compressive Residual Stresses

Shot peening is a manufacturing process intended to give components the final shape and to introduce a compressive residual state of stress inside the material in order to increase fatigue life. The modeling and simulation of the residual stress field resulting from the shot peening process are proposed. The behaviour of the peened target material is supposed to be elastic plastic with bilinear characteristics. The results demonstrated the surface layer affected by compressive residual stresses is very thin and the peak is located on the surface.

Numerical Simulation of Surface Hardened Layer of the Hydraulic Track

2011 ◽  
Vol 194-196 ◽  
pp. 1333-1337
Author(s):  
Run Bo Bai ◽  
Fu Sheng Liu ◽  
Zong Mei Xu
Keyword(s):  
Numerical Simulation ◽  
Finite Element ◽  
Wear Resistance ◽  
Surface Layer ◽  
Hardened Layer ◽  
Distribution Model ◽  
Continuous Change ◽  
Finite Element Software ◽  
Calculation Results ◽  
Surface Hardened Layer

The surface of the large hydraulic track needs thermal treatment for hardening and tempering to improve its wear resistance and bearing capacities. Currently it is still difficult to simulate the hardened layer of the track. For that, this paper firstly put forward a surface layer hardness graded distribution model of the track, and then established a method to measure the hardness of the track in the finite element software. Based on the limit thinking, the meshes of the hardened layer of the track were refined, so as to achieve the purpose of using the discrete mesh to simulate the continuous change of the hardness graded distribution in the hardened layer of the track. Calculation results show that improving the hardness value and the thickness of the hardened layer of the track are benefit to the track’s bearing capacity and deformation stabilization.

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