scholarly journals Optimization on start-up process of high-pressure rotor for large power steam turbine

2016 ◽  
Vol 20 (suppl. 3) ◽  
pp. 815-822 ◽  
Author(s):  
Qiu-Wan Du ◽  
Zhao-Li Zheng ◽  
Yong-Hui Xie
Keyword(s):  
Thermal Stress ◽  
Time Allocation ◽  
Thermal Structure ◽  
Equivalent Stress ◽  
Pattern Search ◽  
Transient Temperature ◽  
Obvious Effect ◽  
Large Power ◽  
Start Up ◽  
Maximum Equivalent Stress

This paper combines thermal-structure coupling technique and pattern search optimization algorithm to establish an optimization system for the start-up process of a turbine unit. Firstly, a finite element model for thermal-structure coupling calculation is established to accurately analyze the transient temperature field and thermal stress field, which can obtain the thermal stress distribution during start-up process. Afterwards, a program of optimization on rotor start-up process is exploited to improve the time allocation in each operating stage of start-up process, which minimizes the maximum equivalent stress of rotor. The maximum equivalent stress has reduced 25.7% after the optimization, which reveals obvious effect.

scholarly journals Analysis of thermal-force coupling stress field under the temperature of alternating of molecular sieve adsorption tower

2021 ◽  
Vol 261 ◽  
pp. 02077
Author(s):  
Chuanping Wang ◽  
Xuezhang Feng ◽  
Xiaoli Yang ◽  
Sha He ◽  
Yingjie Li ◽  
...  
Keyword(s):  
Thermal Stress ◽  
Molecular Sieve ◽  
Equivalent Stress ◽  
Element Model ◽  
Transient Temperature ◽  
Force Coupling ◽  
Maximum Equivalent Stress ◽  
Maximum Residual Stress ◽  
Import And Export ◽  
Complex Temperature

The thermal stress of molecular sieve adsorption tower under transient temperature of 40-290°C is the basis for ensuring the safe operation of the adsorption tower. In this paper, based on the transient thermodynamics theory, the finite element model of the full-size adsorption tower is established. The distribution of thermal stress at the key positions of the tower body is analyzed, and the strength of the maximum equivalent stress position is evaluated. The results show that the maximum residual stress is at the corner of the inner wall of the tower opening to take over the import and export, the maximum is 313.34MPa, and the effect force is gradually diffused along the takeover; The thermal stress on the inside and outside of the skirt is greater than the thermal stress on the inside and outside of the head. The corresponding stress linearization results of each assessment path were evaluated and passed. The strength design, life prediction and maintenance of adsorption tower in complex temperature cross-change conditions provide theoretical basis.

Design Optimization for Fir-Tree Root of Turbine Blade Considering Manufacturing Variations

2013 ◽  
Vol 694-697 ◽  
pp. 2733-2737
Author(s):  
Qin Zhou ◽  
Ming Hui Zhang ◽  
Hui Yong Chen ◽  
Yong Hui Xie
Keyword(s):  
Particle Swarm Optimization ◽  
Turbine Blade ◽  
Equivalent Stress ◽  
Particle Swarm ◽  
Pattern Search ◽  
Design System ◽  
Contact Method ◽  
Swarm Optimization ◽  
Maximum Equivalent Stress ◽  
Manufacturing Variation

An optimization design system for fir-tree root of turbine blade has been developed in this paper. In the system, a parametric model of the blade and rim was established based on the parametric design language APDL, and nonlinear contact method was used for analysis by ANSYS, meanwhile some optimization algorithms, such as Pattern Search Algorithm, Genetic Algorithm, Simulated Annealing Algorithm and Particle Swarm Optimization, were adopted to control the optimizing process. Five cases of manufacturing variation in contact surfaces between root and rim were taken into account, and the design objective was to minimize the maximum equivalent stress of root-rim by optimizing eight critical geometrical dimensions of the root and rim. As a result, the maximum equivalent stress of root-rim decreases markedly after the optimization in all cases. In consideration of both precision and computing time, particle swarm optimization is assessed as the best algorithm to solve structure optimization problem in this work. Corresponding to five different cases of manufacturing variation, the maximum equivalent stress of root and rim reduces by 7%, 8%; 27%, 24%; 27%, 22%; 25%, 19%; 10%, 14% using the Particle Swarm Optimization.

Numerical Analysis of Transient Temperature Field and Thermal Stress on Coke Drum With 1.25Cr-0.5Mo Steel Based on Iterative Algorithm

2017 ◽  
Author(s):  
Zhibing Lu ◽  
Xuedong Chen ◽  
Zhichao Fan ◽  
Jie Dong ◽  
Jinhua Zhu
Keyword(s):  
Temperature Field ◽  
Thermal Stress ◽  
Iterative Algorithm ◽  
Thermal Structure ◽  
Transient Temperature ◽  
Main Process ◽  
Measured Temperature ◽  
Operating Cycle ◽  
Transient Temperature Field ◽  
Variation Characteristics

Coke drum is typical industrial equipment which experiences complex thermal and mechanical cyclic load during its operation, and the thermal stress which is produced by the drastic change of temperature is the main cause of the cracking failure of coke drum. This paper aims at coke drum with 1.25Cr–0.5Mo steel, and is based on iterative algorithm. Then we simulate the process of liquid medium climbing the inner surface of coke drum in the stages of oil filling and water quenching with dynamic thermal boundary, and carry out the numerical calculation of transient temperature field of coke drum in main process stages for one operating cycle. After the comparison of simulated temperature values with the measured temperature data at several locations on the outer surface of coke drum, the appropriate equivalent coefficients of convective heat transfer will be obtained. The variation rules of transient temperature field for the key parts of coke drum are discussed. Based on the simulation results of temperature field, the thermal-structure coupling analysis of coke drum is carried out, and the variation characteristics of thermal stress on coke drum are studied later.

scholarly journals Transient Analysis and Design Improvement of a Gas Turbine Rotor Based on Thermal-Mechanical Method

2018 ◽  
Vol 2018 ◽  
pp. 1-14 ◽  
Author(s):  
Yang Liu ◽  
Qi Yuan ◽  
Guangyu Zhu ◽  
Pu Li
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Transient Analysis ◽  
Equivalent Stress ◽  
Cold Start ◽  
Turbine Rotor ◽  
Transfer Coefficients ◽  
Analysis And Design ◽  
Start Up ◽  
Maximum Equivalent Stress

The rotor is the core component of a gas turbine, and more than 80% of the failures in gas turbines occur in the rotor system, especially during the start-up period. Therefore, the safety assessment of the rotor during the start-up period is essential for the design of the gas turbine. In this paper, the transient equivalent stress of a gas turbine rotor under the cold start-up condition is investigated and the novel tie rod structure is introduced to reduce the equivalent stress. Firstly, a three-dimensional finite element model of the gas turbine rotor is built, and nonlinear contact behaviors such as friction are taken into account. Secondly, the convective heat transfer coefficients of the gas turbine rotor under the cold start-up condition are calculated using thermal dynamic theory. The transient analysis of the gas turbine rotor is conducted considering the thermal load, the centrifugal load, and the pretightening force. The temperature and stress distributions of the rotor under the cold start-up condition are shown in detail. In particular, the generation mechanism of maximum equivalent stress for tie rods and the change tendency of the pretightening force are illustrated in detail. The tie rod holes of the rear shaft and the turbine tie rod are the dangerous locations during the start-up period. Finally, a novel tie rod is proposed to reduce the maximum equivalent stress at the dangerous location. The maximum equivalent stress at this location is decreased by 15%. This paper provides some reference for the design of the gas turbine rotor.

scholarly journals Finite Element Modeling of Residual Stress at Joint Interface of Titanium Alloy and 17-4PH Stainless Steel

Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 629
Author(s):  
Nana Kwabena Adomako ◽  
Sung Hoon Kim ◽  
Ji Hong Yoon ◽  
Se-Hwan Lee ◽  
Jeoung Han Kim
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Stainless Steel ◽  
Finite Element Modeling ◽  
Equivalent Stress ◽  
Stress Gradient ◽  
Joint Interface ◽  
Element Modeling ◽  
Actual Experiment ◽  
Maximum Equivalent Stress

Residual stress is a crucial element in determining the integrity of parts and lifetime of additively manufactured structures. In stainless steel and Ti-6Al-4V fabricated joints, residual stress causes cracking and delamination of the brittle intermetallic joint interface. Knowledge of the degree of residual stress at the joint interface is, therefore, important; however, the available information is limited owing to the joint’s brittle nature and its high failure susceptibility. In this study, the residual stress distribution during the deposition of 17-4PH stainless steel on Ti-6Al-4V alloy was predicted using Simufact additive software based on the finite element modeling technique. A sharp stress gradient was revealed at the joint interface, with compressive stress on the Ti-6Al-4V side and tensile stress on the 17-4PH side. This distribution is attributed to the large difference in the coefficients of thermal expansion of the two metals. The 17-4PH side exhibited maximum equivalent stress of 500 MPa, which was twice that of the Ti-6Al-4V side (240 MPa). This showed good correlation with the thermal residual stress calculations of the alloys. The thermal history predicted via simulation at the joint interface was within the temperature range of 368–477 °C and was highly congruent with that obtained in the actual experiment, approximately 300–450 °C. In the actual experiment, joint delamination occurred, ascribable to the residual stress accumulation and multiple additive manufacturing (AM) thermal cycles on the brittle FeTi and Fe2Ti intermetallic joint interface. The build deflected to the side at an angle of 0.708° after the simulation. This study could serve as a valid reference for engineers to understand the residual stress development in 17-4PH and Ti-6Al-4V joints fabricated with AM.

scholarly journals Numerical Simulation and Experimental Study on Axial Stiffness and Stress Deformation of the Braided Corrugated Hose

2021 ◽  
Vol 11 (10) ◽  
pp. 4709
Author(s):  
Dacheng Huang ◽  
Jianrun Zhang
Keyword(s):  
Numerical Simulation ◽  
Geometric Model ◽  
Equivalent Stress ◽  
Element Model ◽  
Maximum Error ◽  
Structural Features ◽  
Axial Stiffness ◽  
Frictional Stress ◽  
Maximum Equivalent Stress ◽  
Simulation Results

To explore the mechanical properties of the braided corrugated hose, the space curve parametric equation of the braided tube is deduced, specific to the structural features of the braided tube. On this basis, the equivalent braided tube model is proposed based on the same axial stiffness in order to improve the calculational efficiency. The geometric model and the Finite Element Model of the DN25 braided corrugated hose is established. The numerical simulation results are analyzed, and the distribution of the equivalent stress and frictional stress is discussed. The maximum equivalent stress of the braided corrugated hose occurs at the braided tube, with the value of 903MPa. The maximum equivalent stress of the bellows occurs at the area in contact with the braided tube, with the value of 314MPa. The maximum frictional stress between the bellows and the braided tube is 88.46MPa. The tensile experiment of the DN25 braided corrugated hose is performed. The simulation results are in good agreement with test data, with a maximum error of 9.4%, verifying the rationality of the model. The study is helpful to the research of the axial stiffness of the braided corrugated hose and provides the base for wear and life studies on the braided corrugated hose.

Steady-State Thermal Stresses in Wedge-Shaped Cutting Tools

1975 ◽  
Vol 97 (3) ◽  
pp. 1060-1066
Author(s):  
P. F. Thomason
Keyword(s):  
Thermal Stress ◽  
Steady State ◽  
Metal Cutting ◽  
Thermal Stresses ◽  
Heat Conduction Problem ◽  
Equivalent Stress ◽  
Cutting Tools ◽  
Thermoelastic Stress ◽  
Plastic State ◽  
Steady State Heat

Closed form expressions for the steady-state thermal stresses in a π/2 wedge, subject to constant-temperature heat sources on the rake and flank contact segments, are obtained from a conformal mapping solution to the steady-state heat conduction problem. It is shown, following a theorem of Muskhelishvili, that the only nonzero thermal stress in the plane-strain wedge is that acting normal to the wedge plane. The thermal stress solutions are superimposed on a previously published isothermal cutting-load solution, to give the complete thermoelastic stress distribution at the wedge surfaces. The thermoelastic stresses are then used to determine the distribution of the equivalent stress, and this gives an indication of the regions on a cutting tool which are likely to be in the plastic state. The results are discussed in relation to the problems of flank wear and rakeface crater wear in metal cutting tools.

Optimization design of titanium alloy connecting rod based on structural topology optimization

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Bin Zheng ◽  
Yi Cai ◽  
Kelun Tang
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Topology Optimization ◽  
Optimization Design ◽  
Equivalent Stress ◽  
Connecting Rod ◽  
Element Analysis ◽  
Content Type ◽  
The Finite Element Analysis ◽  
Maximum Equivalent Stress

Purpose The purpose of this paper is to realize the lightweight of connecting rod and meet the requirements of low energy consumption and vibration. Based on the structural design of the original connecting rod, the finite element analysis was conducted to reduce the weight and increase the natural frequencies, so as to reduce materials consumption and improve the energy efficiency of internal combustion engine. Design/methodology/approach The finite element analysis, structural optimization design and topology optimization of the connecting rod are applied. Efficient hybrid method is deployed: static and modal analysis; and structure re-design of the connecting rod based on topology optimization. Findings After the optimization of the connecting rod, the weight is reduced from 1.7907 to 1.4875 kg, with a reduction of 16.93%. The maximum equivalent stress of the optimized connecting rod is 183.97 MPa and that of the original structure is 217.18 MPa, with the reduction of 15.62%. The first, second and third natural frequencies of the optimized connecting rod are increased by 8.89%, 8.85% and 11.09%, respectively. Through the finite element analysis and based on the lightweight, the maximum equivalent stress is reduced and the low-order natural frequency is increased. Originality/value This paper presents an optimization method on the connecting rod structure. Based on the statics and modal analysis of the connecting rod and combined with the topology optimization, the size of the connecting rod is improved, and the static and dynamic characteristics of the optimized connecting rod are improved.

Thermo-mechanical analysis and optimization of functionally graded rotating disks

2020 ◽  
Vol 55 (5-6) ◽  
pp. 159-171
Author(s):  
Hassan Mohamed Abdelalim Abdalla ◽  
Daniele Casagrande ◽  
Luciano Moro
Keyword(s):  
Finite Element ◽  
Equivalent Stress ◽  
Rotating Disk ◽  
Mechanical Analysis ◽  
Theory Of Elasticity ◽  
Functionally Graded ◽  
Rotating Disks ◽  
Maximum Equivalent Stress ◽  
Quadratic Programming Method ◽  
Stress Uniformity

The behavior of thermo-mechanical stresses in functionally graded axisymmetric rotating hollow disks with variable thickness is analyzed. The material is assumed to be functionally graded in the radial direction. First, a two-dimensional axisymmetric model of the functionally graded rotating disk is developed using the finite element method. Exact solutions for stresses are then obtained assuming that the plane theory of elasticity holds. These solutions are in accordance with finite element ones, thus showing the validity of the assumption. Finally, in order to reduce the maximum equivalent stress along the radius, the optimization of the material distribution is addressed. To avoid subsequent finite element simulations in the optimization process, which can be computationally demanding, a nonlinear constrained optimization problem is proposed, for which the solution is obtained numerically by the sequential quadratic programming method, showing prominent results in terms of equivalent stress uniformity.

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