LCF Assessment of Electron-Beam-Welded Notched Parts of Nickel-Based Superalloy Inconel 718

2014 ◽  
Author(s):  
Huang Yuan ◽  
Jie Fang
Keyword(s):  
Fatigue Life ◽  
Critical Distance ◽  
Instrumented Indentation ◽  
Critical Plane ◽  
Plastic Properties ◽  
Welding Material ◽  
Weld Joints ◽  
Nickel Based Superalloy ◽  
Element Simulation ◽  
Indentation Analysis

In the present work the local mechanical behavior and fatigue resistance of the welding material were investigated with help of the instrumented indentation technique in combining with FEM computations. By assuming a power-law strain hardening, the elastic-plastic properties of the welding material were identified from inverse indentation analysis with help of finite element simulation. A critical plane based Cruse-Meyer model was introduced to predict the LCF fatigue life of the weld joints. Combined with the critical distance concept, the fatigue life in center-holed specimens was investigated and verified with experiments.

scholarly journals Fatigue Analysis of NiTi Rotary Endodontic Files through Finite Element Simulation: Effect of Root Canal Geometry on Fatigue Life

2021 ◽  
Vol 10 (23) ◽  
pp. 5692
Author(s):  
Victor Roda-Casanova ◽  
Antonio Pérez-González ◽  
Álvaro Zubizarreta-Macho ◽  
Vicente Faus-Matoses
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Root Canal ◽  
Numerical Procedure ◽  
Element Model ◽  
Radius Of Curvature ◽  
Critical Plane ◽  
Element Analysis ◽  
Element Simulation ◽  
Critical Plane Approach

This article describes a numerical procedure for estimating the fatigue life of NiTi endodontic rotary files. An enhanced finite element model reproducing the interaction of the endodontic file rotating inside the root canal was developed, which includes important phenomena that allowed increasing the degree of realism of the simulation. A method based on the critical plane approach was proposed for extracting significant strain results from finite element analysis, which were used in combination with the Coffin–Manson relation to predict the fatigue life of the NiTi rotary files. The proposed procedure is illustrated with several numerical examples in which different combinations of endodontic rotary files and root canal geometries were investigated. By using these analyses, the effect of the radius of curvature and the angle of curvature of the root canal on the fatigue life of the rotary files was analysed. The results confirm the significant influence of the root canal geometry on the fatigue life of the NiTi rotary files and reveal the higher importance of the radius of curvature with respect to the angle of curvature of the root canal.

Method for Determining the Plastic Properties of Metallic Materials by Instrumented Indentation with Dual Pyramidal Indenters

2014 ◽  
Vol 941-944 ◽  
pp. 1445-1452
Author(s):  
Wei Chen ◽  
De Jun Ma ◽  
Jia Liang Wang ◽  
Yong Huang
Keyword(s):  
Finite Element ◽  
Yield Strength ◽  
Strain Hardening ◽  
Engineering Application ◽  
Strain Hardening Exponent ◽  
Metallic Materials ◽  
Instrumented Indentation ◽  
Plastic Properties ◽  
Functional Relationships ◽  
Element Simulation

Method for determining the plastic properties of metallic materials was proposed based on the functional relationships between representative stress, representative strain and nominal hardness which were established with the aid of dimensional analysis and finite element simulation. The errors of 0.2% yield strength and strain hardening exponent of five engineering metals were from-17.1% to 15.4% and from -0.125 to 0.11, respectively,which satisfied the need of engineering application and verified the effectiveness of the method.

A weight function method for multiaxial low-cycle fatigue life prediction under variable amplitude loading

2018 ◽  
Vol 53 (4) ◽  
pp. 197-209 ◽  
Author(s):  
Xiao-Wei Wang ◽  
De-Guang Shang ◽  
Yu-Juan Sun
Keyword(s):  
Fatigue Life ◽  
Weight Function ◽  
Life Prediction ◽  
Function Method ◽  
Low Cycle Fatigue ◽  
Fatigue Life Prediction ◽  
Cycle Fatigue ◽  
Critical Plane ◽  
Variable Amplitude ◽  
Weight Function Method

A weight function method based on strain parameters is proposed to determine the critical plane in low-cycle fatigue region under both constant and variable amplitude tension–torsion loadings. The critical plane is defined by the weighted mean maximum absolute shear strain plane. Combined with the critical plane determined by the proposed method, strain-based fatigue life prediction models and Wang-Brown’s multiaxial cycle counting method are employed to predict the fatigue life. The experimental critical plane orientation and fatigue life data under constant and variable amplitude tension–torsion loadings are used to verify the proposed method. The results show that the proposed method is appropriate to determine the critical plane under both constant and variable amplitude loadings.

Invariant stress state parameters for forging upsetting of magnesium in the shell

2021 ◽  
Vol 23 (1) ◽  
pp. 79-88
Author(s):  
Yuriy Loginov ◽  
◽  
Yuliya Zamaraeva ◽  
◽  
◽  
...  
Keyword(s):  
Stress State ◽  
Deformable Body ◽  
Great Influence ◽  
Precipitation Process ◽  
Software Module ◽  
Plastic Properties ◽  
Compressive Stresses ◽  
Element Simulation ◽  
Processed Material ◽  
Mathematical Evaluation

Introduction. For pressure treatment of low-plastic metals, it is necessary to develop special techniques for increasing plasticity. In the cold state, an increase in plastic properties is possible due to an increase in the level of compressive stresses during deformation. In the processes of forging precipitation, this is achieved by using shells or clips of various types. At the same time, the configuration of the precipitation tool also matters. To create additional compressive stresses and increase the ductility of the metal, the working surface of the tool can be configured differently than with a normal free draft, where it is obviously larger than the contact surface area of the workpiece, so that metal broadening can occur. The stress state has a great influence on the plasticity of the processed material. This state is described by methods of tensor representation, but to assess the situation, it is customary to use invariants of tensors in one form or another, which eliminates the influence of coordinates on the results of the analysis. In the sections of deformable body mechanics dealing with the influence of the stress state on plasticity, the first, but sometimes other invariants of the stress tensor are used, the invariants themselves are transformed into the stress state indicator and the lode coefficient. The aim of the work: mathematical evaluation of invariant parameters of the stress state of the magnesium precipitation process at room temperature, according to the results of which it is possible to obtain a positive result in real experiments. Research methods: finite element simulation using the DEFORM software module. Results and discussion. The theoretical justification of increasing the plasticity of the magnesium billet in the process of precipitation in the cage without its compression is carried out. An increase in the stress state index modulo 2...5 times is revealed, which contributes to an increase in the plasticity of the metal. At the same time, a zone with a lode coefficient close to zero is identified. It is adjacent to the middle of the height of the workpiece at the point of contact with the cage and can be a dangerous cross-section from the position of crack formation.

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