scholarly journals Virtual Minimization of Residual Stress and Deflection Error in the Five-Axis Milling of Turbine Blades

2021 ◽  
Vol 67 (5) ◽  
pp. 235-244
Author(s):  
Mohsen Soori ◽  
Mohammed Asmael
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Virtual Environments ◽  
Turbine Blades ◽  
Research Work ◽  
Machining Parameters ◽  
Virtual Machining ◽  
Machined Parts ◽  
Machining System ◽  
Five Axis

To simulate and analyse the real machined parts in virtual environments, virtual machining systems are applied to the production processes. Due to friction, chip forming, and the heat produced in the cutting zone, parts produced using machining operation have residual stress effects. The machining force and machining temperature can cause the deflection error in the machined turbine blades, which should be minimized to increase the accuracy of machined blades. To minimize the residual stress and deflection error of machined parts, optimized machining parameters can be obtained. In the present research work, the application of a virtual machining system is presented to predict and minimize the residual stress and deflection error in a five-axis milling operations of turbine blades. In order to predict the residual stress and deflection error in machined turbine blades, finite element analysis is implemented. Moreover, to minimize the residual stress and deflection error in machined turbine blades, optimized parameters of machining operations are obtained by using a genetic algorithm. To validate the research work, experimentally determining residual stress by using a X-ray diffraction method from the machined turbine blades is compared with the finite element results obtained from the virtual machining system. Also, in order to obtain the deflection error, the machined blades are measured by using the CMM machines. Thus, the accuracy and reliability of machined turbine blades can be increased by analysing and minimizing the residual stress and deflection error in virtual environments.

scholarly journals Surface Roughness Prediction and Minimization in 5-Axis Milling Operations of Gas Turbine Blades

2021 ◽  
Author(s):  
Arameh Eyvazian ◽  
Farayi Musharavati ◽  
Afrasyab Khan ◽  
Mohsen Soori ◽  
Tamer A. Sebaey ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Gas Turbine ◽  
Turbine Blades ◽  
Machining Process ◽  
Machining Parameters ◽  
Gas Turbine Blades ◽  
Virtual Machining ◽  
Machined Parts ◽  
Machining System

Abstract To enhance the quality of machined parts, virtual machining systems are presented in this study. In the turbine blades, the minimization of the surface roughness of the blades can decrease the Reynolds number to decrease the loss of energy in power generation. Due to difficulties of polishing process in minimizing the surface roughness of machined blades, the optimized machining parameters for minimizing the surface roughness is an effective solution for the problem. In this study, a virtual machining system is developed to predict and minimize the surface roughness in 5-Axis machining operations of gas turbine blades. To minimize the surface roughness, the machining parameters were optimized by the Genetic algorithm. To validate the developed system, the turbine blades were machined using a 5-Axis CNC machine tool and the machined blades were measured using the CMM machine to obtain the surface roughness of machined parts. So, a 41.29% reduction in the measured surface roughness and a 42.09% reduction in the predicted surface roughness are obtained using the optimized machining parameters. The developed virtual machining system can be applied in the machining process of turbine blades to enhance the surface quality of machined blades and thus improve the efficiency of gas turbines.

scholarly journals Deflection Error Prediction and Minimization in 5-Axis Milling Operations of Thin-Walled Impeller Blades

2020 ◽  
Author(s):  
Mohsen Soori ◽  
Mohammed Asmael
Keyword(s):  
Machine Tools ◽  
Turbine Blades ◽  
Cnc Machining ◽  
Cnc Machine Tools ◽  
Machining Parameters ◽  
Cnc Machine ◽  
Virtual Machining ◽  
Machining System ◽  
Thin Walled ◽  
Machining Operations

Abstract To enhance accuracy as well as efficiency in process of machining operations, the virtual machining systems are developed. Free from surfaces of sophisticated parts such as turbine blades, airfoils, impellers, and aircraft components are produced by using the 5-axis CNC machine tools which can be analyzed and developed by using virtual machining systems. The machining operations of thin walled structures such as impeller blades are with deflection errors due to cutting forces and cutting temperatures. The flexibility of thin walled impeller blades can cause machining defects such as overcut or undercut. So, the desired accuracy in the machined impeller blades can be achieved by decreasing the deflection error in the machining operations. To minimize the deflection of machined impeller blades, optimized machining parameters can be obtained. An application of virtual machining system in predicting and minimizing the deflection errors of 5-Axis CNC machining operations of impeller blades is presented in the study to increase accuracy and efficiency in process of part production. The finite element analysis is applied to obtain the deflection error in machined impeller blades. In order to minimize the deflection error of impeller blades in the machining operations, the optimization methodology based on the Genetic algorithm is applied. The impeller is machined by using the 5-axis CNC machine tool in order to validate the developed virtual machining system in the study. Then, the machined impeller is measured by using the CMM machines to obtain the deflection error. As a result, the deflection error of in machining operations of impeller by using 5-Axis CNC machine tools can be decreased in order to enhance accuracy and efficiency of part manufacturing.

Instability Parameter for Machined Parts

1983 ◽  
Vol 105 (3) ◽  
pp. 133-136 ◽  
Author(s):  
A. Israeli ◽  
J. Benedek
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Single Point ◽  
Machining Parameters ◽  
Machining Processes ◽  
Etching Technique ◽  
Parametric Relationship ◽  
Machined Parts ◽  
Instability Parameter ◽  
Stress Profiles

The production of precision parts requires manufacturing processes which produce low residual stresses. This study was designed to investigate the parametric relationship between machining processes and residual stress distribution. Sets of steel specimens were single point turned at different feeds. The residual stress profiles of these specimens were monitored, using a continuous etching technique. A “Specific Instability Potential” parameter, derived from the strain energy of the residual stresses, was found to relate directly to the machining parameters. It is suggested that the Specific Instability Potential can be used as a parameter for specifying processing operations.

Three-Dimensional Finite Element Prediction of Machining-Induced Stresses

Manufacturing ◽  
2003 ◽  
Author(s):  
T. D. Marusich ◽  
S. Usui ◽  
R. J. McDaniel
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Metal Cutting ◽  
Three Dimensional ◽  
Constitutive Models ◽  
Fatigue Loading ◽  
Cyclic Fatigue ◽  
Fem Model ◽  
Machined Parts ◽  
Three Dimensional Finite Element

Controlling residual stress in machined workpiece surfaces is necessary in situations where service requirements subject structural members to cyclic fatigue loading. It is desirable to have a predictive capability when attempting to optimize machined parts for cost while taking into account residual stress considerations. One such method of machining modeling is application of the finite element method (FEM). A three-dimensional FEM model is presented which includes fully adaptive unstructured mesh generation, tight thermo-mechanically coupling, deformable tool-chip-workpiece contact, interfacial heat transfer across the tool-chip boundary, momentum effects at high speeds and constitutive models appropriate for high strain rate, finite deformation analyses. The FEM model is applied to nose turning operations with stationary tools. To substantiate the efficacy of numerical and constitutive formulations used, metal cutting tests are performed, residual stress profiles collected, and validation comparison is made.

Finite Element Analysis of Turbine Blades

1991 ◽  
Author(s):  
A. Carnero ◽  
J. Kubiak ◽  
A. López
Keyword(s):  
Finite Element Method ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Radio Telemetry ◽  
Turbine Blades ◽  
Research Work ◽  
Mode Shapes ◽  
The Finite Element Method ◽  
Element Analysis ◽  
Element Method

Abstract Frequent failures of long turbine blades forced an electrical utility to sponsor research work to find out the causes of the failures. One of the techniques applied in this work was finite element analysis. The paper presents an application of the finite element method for computation of the natural frequencies, steady-state and alternating stresses, deformations due to forces acting on the blades and modal shapes of the turbine long blade groups. Two stages, L-1 and L-0 of the low pressure part of a steam turbine, were analyzed. It has been postulated that the results of the FEM analysis of the blades groups would be complementary to those obtained from the radio telemetry test (which was carried out during operation of the turbine) for the purpose of blade group failure diagnosis. However, the results of the analysis show that the FEM results were decisive in blade failure identification (L-1 stage moving blades). The graphical post processor of the FEM code revealed that the first blade in the group was the one most protruding from the stage rotating plane, thus indicating that this blade was the most prone to erosion. This was confirmed in the inspection of the turbine. This finding showed why only the first blade in the group was cracked (erosion induced cracks). The mode shapes were also very helpful in identifying other types of cracks which affected other parts of the blades. It can be concluded that the finite element method is very useful for identification of very difficult cases of blade faults and indispensable for carrying out modifications to prevent future failures.

Residual Stress and Wave Reflectivity When Laser Peening Thin Curved Sections

2011 ◽  
Author(s):  
Arif Malik ◽  
Xiaopeng Lai ◽  
Kristina Langer
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Fatigue Life ◽  
Near Infrared ◽  
Experimental Testing ◽  
Turbine Blades ◽  
Value Added ◽  
Laser Peening ◽  
Widespread Application ◽  
Thin Sections

Laser Peening is an emerging technology that shows promise for extending the fatigue life of special-purpose metal components in the aerospace, automotive, medical, manufacturing, and other industries. While laser peening has been shown to extend the fatigue life of metal components such as turbine blades and other high value-added components, the technology is not yet understood well enough to deploy it cost-effectively, without extensive experimental testing, for widespread application in diverse industries. Because laser peening can adversely affect fatigue life if the process parameters are not selected appropriately, identification of tamping layers, pulse energy densities, shot patterns, and other parameters is critical to the component geometry, material, and loading. When laser peening thin sections, preliminary finite element studies indicate that reflectivity of shock waves can induces regions of residual stress or damage on opposing surfaces. Through a series of finite element simulations, this work explores the effects of stress wave reflectivity on component life for thin, curved, 6061-T6 aluminum alloy sections. The simulations are based on an 800 mJ, 5 ns pulsed, near-infrared laser, serves to define the pressure pulse boundary condition, and allow more reliable deployment of laser peening technology.

Tool Deflection Error of Three-Axis Computer Numerical Control Milling Machines, Monitoring and Minimizing by a Virtual Machining System

2016 ◽  
Vol 138 (8) ◽  
Author(s):  
Mohsen Soori ◽  
Behrooz Arezoo ◽  
Mohsen Habibi
Keyword(s):  
Manufacturing Systems ◽  
Optimization Technique ◽  
Dimensional Accuracy ◽  
Virtual Manufacturing ◽  
Numerical Control ◽  
Free Form ◽  
Machining Parameters ◽  
Tool Deflection ◽  
Virtual Machining ◽  
Machining System

Virtual manufacturing systems carry out the simulation of manufacturing processes in digital environment in order to increase accuracy as well as productivity in part production. There are different error sources in machine tools, such as tool deflection, geometrical deviations of moving axis, and thermal distortions of machine tool structures. The errors due to tool deflection are caused by cutting forces and have direct effects on dimensional accuracy, surface roughness of the parts, and efficient life of the cutting tool, holder, and spindle. This paper presents an application of virtual machining systems in order to improve the accuracy and productivity of part manufacturing by monitoring and minimizing the tool deflection error. The tool deflection error along machining paths is monitored to present a useful methodology in controlling the produced parts with regard to desired tolerances. Suitable tool and spindle can also be selected due to the ability of error monitoring. In order to minimize the error, optimization technique based on genetic algorithms is used to determine optimized machining parameters. Free-form profile of virtual and real machined parts with tool deflection error is compared in order to validate reliability as well as accuracy of the software.

New UK Research Programme on Residual Stresses

2006 ◽  
Author(s):  
Steve K. Bate ◽  
Chris Watson
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Residual Stresses ◽  
Structural Integrity ◽  
Stress Measurement ◽  
Research Work ◽  
Research Programme ◽  
Residual Stress Measurement ◽  
Engineering Structures ◽  
The Uk

A new long-term research programme has been launched in the UK. This involves Rolls-Royce plc and Serco Assurance, supported by UK industry and academia. A significant part of this programme is aimed at progressing the understanding of weld residual stresses and the implementation of finite element simulation and residual stress measurement for assessing the structural integrity of engineering structures and components. The work includes: (1) Finite element modelling to investigate heat source representation, material behaviour and 3D v 2D effects. (2) Design and manufacture of mock-ups for supporting validation. (3) Residual stress measurement. (4) Weld design. (5) Residual stress profiles. (6) Material testing. (7) Development of a procedure for residual stress modelling. The work is being undertaken by a combination of finite element analyses and residual stress measurement using a variety of techniques. This paper presents an overview of the research work being undertaken and provides examples of the outcome of some of the studies obtained to-date.

Strength of Shear Web With Circular Hole in Wind Turbine Blades and Using Digital Twining Concept to Reduce Material Testing

2017 ◽  
Author(s):  
Anil K. Sahoo ◽  
Utsa Majumder ◽  
Michael W. Nielsen ◽  
Jesper H. Garm
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Wind Turbine ◽  
Composite Structures ◽  
Turbine Blades ◽  
Research Work ◽  
Element Model ◽  
Failure Behavior ◽  
Wind Turbine Blades ◽  
The Finite Element Model

This research work summarizes the study of the structural analysis of shear webs (present in wind turbine blades, sometimes also called as spars) with holes. The webs are sandwich composite structures which are supposed to carry the shear loads coming from the wind pressure and the holes are necessary for non-structural requirements of the wind turbine. The shear webs are strong structures and it is tough to test them to failure in the lab. Hence a structural representative component with lesser dimensions has been tested in the lab to accommodate the capability of the test machines. However, this component test results cannot be directly used in the wind turbine blade structural verification as the web size is much larger in real life. A finite element model is developed to simulate the test specimen and its failure behavior. The concept in this modelling approach is to prepare a digital copy of the actual specimen which will follow the same load-displacement behavior and can predict the same failure as seen in the test coupon. The finite element model is verified for failure using known failure criteria for composite sandwich structures as well as with analytical calculations. This makes sure that the finite element model is a good ‘digital twin’ and simulates the test component behavior one to one. Later, this finite element model is extended to the size of the actual web structure (a family of FE models with different dimensions) to scale up the failure prediction to actual stiffness level.

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