Evaluation of plastic deformation and prediction of thermal mechanical fatigue life of an Al–Si alloy piston for diesel engines

2021 ◽  
Author(s):  
Ziliang Li ◽  
Jianxing Li ◽  
Ye Zhu ◽  
Jinbao Guo ◽  
Meng Li ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Fatigue Life ◽  
Diesel Engines ◽  
Thermal Mechanical Fatigue ◽  
Mechanical Fatigue

Life Assessment of a Coke Drum by Using the Thermal-Mechanical Fatigue Properties and Laser Scanning Approach

2020 ◽  
Author(s):  
Zhiyuan Han ◽  
Guoshan Xie ◽  
Zengchao Wang ◽  
Jianzhong Yin ◽  
Jin Shi
Keyword(s):  
Fatigue Life ◽  
Laser Scanning ◽  
Low Cycle Fatigue ◽  
Complex Loading ◽  
Operating Conditions ◽  
Life Assessment ◽  
Fatigue Properties ◽  
Element Analysis ◽  
Thermal Mechanical Fatigue ◽  
Mechanical Fatigue

Abstract Coke drums are critical equipments in delayed coking plants, which are operated under severe thermal-mechanical conditions by cyclic heating and quenching processes. Cracks are usually developed during service because of severe plastic deformation and low-cycle fatigue. Thus, the assessment of the deformation severity and remaining life is important for safety operating of the coke drums. This study investigated the bulging damage and fatigue life of 6 coke drums after 16 years and 22 years of service in China. A thermal-mechanical fatigue test were first performed to simulate complex loading condition experienced by the coke drum. The thermal-mechanical fatigue life curve of the fabrication material was obtained. Then, a internal laser scanning was employed to measure the deformation and bulges of drum shells. The finite element analysis was developed to calculate the cyclic stress and strain and bulging severity based on the laser mapping and operating conditions. The fatigue life of the coke drum was assessed by the Coffin-Manson-Basquin’s relationship. The life evaluation results of different methods were compared and analyzed. The results showed that a reasonable life of the coke drum can be obtained by using the thermal-mechanical fatigue properties and laser scanning approach.

scholarly journals Simulation-based design and optimization and fatigue characteristics for high-speed backplane connector

2019 ◽  
Vol 11 (6) ◽  
pp. 168781401985675 ◽  
Author(s):  
Rong Yuan ◽  
Haiqing Li ◽  
Qingyuan Wang
Keyword(s):  
Fatigue Life ◽  
High Speed ◽  
Thermal Structure ◽  
Extraction Process ◽  
Element Analysis ◽  
Design And Optimization ◽  
Thermal Mechanical Fatigue ◽  
Mechanical Fatigue ◽  
Application Systems ◽  
Fatigue Characteristics

In high-speed interconnect systems, high-speed backplane connectors are widely utilized. Its mechanical reliability is related to the stability of entire application systems directly. Insertion–extraction force and fatigue characteristics are important factors that affect the reliability of high-speed backplane connectors. To enhance the reliability of high-speed backplane connectors, in this study, a single CAD/CAE parametric model of the contacts is established. Not only the dynamic analysis of the insertion and extraction process but also the electro-thermal-structure coupling of the contacts are carried out using finite element analysis. By changing the insertion position of male terminal, the length of female terminal, and the thickness of male terminal, the insertion–extraction force can be optimized. According to the simulation of the insertion–extraction force and the electric-thermal-structure coupling results, both the mechanical life of this connector and the thermal-mechanical fatigue life under electrifying condition are evaluated. The results show that the mechanical life and thermal-mechanical fatigue life were 376 cycles and 286 cycles, respectively. The design solutions can provide the reference for the structural design, optimization, and fatigue life prediction of high-speed backplane connector.

scholarly journals Influence of turning tool wear on the surface integrity and anti-fatigue behavior of Ti1023

2021 ◽  
Vol 13 (4) ◽  
pp. 168781402110112
Author(s):  
Li Xun ◽  
Wang Ziming ◽  
Yang Shenliang ◽  
Guo Zhiyuan ◽  
Zhou Yongxin ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Plastic Deformation ◽  
Titanium Alloy ◽  
Fatigue Life ◽  
Tool Wear ◽  
Surface Integrity ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Machined Surface ◽  
Deformation Layer

Titanium alloy Ti1023 is a typical difficult-to-cut material. Tool wear is easy to occur in machining Ti1023, which has a significant negative effect on surface integrity. Turning is one of the common methods to machine Ti1023 parts and machined surface integrity has a direct influence on the fatigue life of parts. To control surface integrity and improve anti-fatigue behavior of Ti1023 parts, it has an important significance to study the influence of tool wear on the surface integrity and fatigue life of Ti1023 in turning. Therefore, the effect of tool wear on the surface roughness, microhardness, residual stress, and plastic deformation layer of Ti1023 workpieces by turning and low-cycle fatigue tests were studied. Meanwhile, the influence mechanism of surface integrity on anti-fatigue behavior also was analyzed. The experimental results show that the change of surface roughness caused by worn tools has the most influence on anti-fatigue behavior when the tool wear VB is from 0.05 to 0.25 mm. On the other hand, the plastic deformation layer on the machined surface could properly improve the anti-fatigue behavior of specimens that were proved in the experiments. However, the higher surface roughness and significant surface defects on surface machined utilizing the worn tool with VB = 0.30 mm, which leads the anti-fatigue behavior of specimens to decrease sharply. Therefore, to ensure the anti-fatigue behavior of parts, the value of turning tool wear VB must be rigorously controlled under 0.30 mm during finishing machining of titanium alloy Ti1023.

Effect of Residual Stress or Plastic Deformation History on Fatigue Life Simulation of Pipeline Dents

2018 ◽  
Author(s):  
Xian-Kui Zhu ◽  
Rick Wang
Keyword(s):  
Residual Stress ◽  
Plastic Deformation ◽  
Fatigue Life ◽  
Residual Stresses ◽  
Three Dimensional ◽  
Strain History ◽  
Deformation History ◽  
Stress Strain ◽  
Element Analysis ◽  
Fea Model

Mechanical dents often occur in transmission pipelines, and are recognized as one of major threats to pipeline integrity because of the potential fatigue failure due to cyclic pressures. With matured in-line-inspection (ILI) technology, mechanical dents can be identified from the ILI runs. Based on ILI measured dent profiles, finite element analysis (FEA) is commonly used to simulate stresses and strains in a dent, and to predict fatigue life of the dented pipeline. However, the dent profile defined by ILI data is a purely geometric shape without residual stresses nor plastic deformation history, and is different from its actual dent that contains residual stresses/strains due to dent creation and re-rounding. As a result, the FEA results of an ILI dent may not represent those of the actual dent, and may lead to inaccurate or incorrect results. To investigate the effect of residual stress or plastic deformation history on mechanics responses and fatigue life of an actual dent, three dent models are considered in this paper: (a) a true dent with residual stresses and dent formation history, (b) a purely geometric dent having the true dent profile with all stress/strain history removed from it, and (c) a purely geometric dent having an ILI defined dent profile with all stress/strain history removed from it. Using a three-dimensional FEA model, those three dents are simulated in the elastic-plastic conditions. The FEA results showed that the two geometric dents determine significantly different stresses and strains in comparison to those in the true dent, and overpredict the fatigue life or burst pressure of the true dent. On this basis, suggestions are made on how to use the ILI data to predict the dent fatigue life.

Sign in / Sign up

Export Citation Format

Share Document