scholarly journals A method to select the finite element models for the structural analysis of machine tools

2019 ◽  
Vol 1399 ◽  
pp. 044033
Author(s):  
A N Polyakov ◽  
S V Kamenev
Keyword(s):  
Finite Element ◽  
Structural Analysis ◽  
Machine Tools ◽  
Finite Element Models

Materials Aging Degradation of Reactor Vessel Internals: Part III—Structural Evaluation and Local Finite Element Models

2009 ◽  
Author(s):  
Matthew D. Snyder ◽  
Tama´s R. Liszkai ◽  
Anne Demma
Keyword(s):  
Finite Element ◽  
Structural Analysis ◽  
Constitutive Model ◽  
Reactor Vessel ◽  
Finite Element Models ◽  
Local Models ◽  
Bolted Connections ◽  
The Core ◽  
Potential Failure ◽  
Reactor Internals

Pressurized water reactor (PWR) internals components can experience material aging and degradation due to irradiation. The purpose of the functionality analysis is to provide a best-estimate evaluation of the reactor internals core barrel assembly for materials degradation to see if the components retain their function. The evaluation uses an irradiated material-specific constitutive model for use in a finite element analysis [1] representing the current state of knowledge for plasticity, creep, stress relaxation, void swelling, and embrittlement. This constitutive model is a function of temperature and fluence. The analysis focuses on finding the integrated effects of material aging combined with steady-state operational characteristics of the reactor internals. In order to evaluate the potential failure mechanisms of the core barrel assembly, finite element models were developed capable of representing the complex interactions between the components. The goal of this specific analysis is to characterize the potential failure modes, spatial and chronological distribution of potential component failures for a representative model of the Babcock & Wilcox-type (B&W) designed plants. Evaluation of the reactor vessel internals for materials aging degradation involves three analytical calculations. Radiation calculations of the core provide essential information on radiation dose and heat rates of the internals. The computational fluid dynamics domain (CFD) allows evaluation of the internals temperatures through conjugate heat transfer (CHT) analysis coupled with coolant flow. Detailed structural analysis of the internals components and bolted connections is the third major physics field involved, which facilitates the development of operating stress fields within the internals. Structural analysis was performed as two parts. First, a global structural model of the core barrel assembly was used to represent the interaction of components of the core barrel assembly during 60 years of operation. The global model does not include detail of the areas of stress concentration within bolted connections. Therefore local models of selected bolts were developed. Results of both the global and local models were used as a basis for evaluating age-related effects. The description of the functionality analysis for the B&W designed RV internals is divided into three papers. Part I was presented in PVP-2008 [2] and included a description of the overall methodology with special attention to CFD-CHT evaluations. Part II, to be presented at PVP 2009 [2] describes global structural finite element models. Part III, presented in this paper, presents a description of local models of bolted connections, results, and conclusions.

Methodology for the Efficient Analysis of Thermal and Thermo-Elastic Behaviour of Machine Tools

2014 ◽  
Vol 1018 ◽  
pp. 395-402 ◽  
Author(s):  
Knut Großmann ◽  
Alexander Galant ◽  
Marcel Merx ◽  
Mirko Riedel
Keyword(s):  
Finite Element ◽  
Machine Tools ◽  
Order Reduction ◽  
Computational Effort ◽  
Elastic Behaviour ◽  
Limiting Factor ◽  
Finite Element Models ◽  
Model Matching ◽  
Thermally Induced ◽  
Improve Model

Thermally induced deviations become the limiting factor for the precision of machine tools. Structure-based finite-element models of high resolution can estimate these deviations with high accuracy but have also a high computational effort. With model order reduction (MOR) these models can be converted into structure-preserving reduced-order finite-element models (FEM-MOR-models) which can be solved very efficiently in MATLAB/Simulink®. To improve model matching selective thermography is used. Selective thermography is a measurement method providing high structural resolution and minimal instrumentation expense due to the use of thermography and photogrammetric methods.

Materials Aging Degradation of Reactor Vessel Internals: Part II—Structural Evaluation and Global Finite Element Models

2009 ◽  
Author(s):  
Tama´s R. Liszkai ◽  
Matthew Snyder ◽  
Anne Demma
Keyword(s):  
Finite Element ◽  
Structural Analysis ◽  
Constitutive Model ◽  
Reactor Vessel ◽  
Finite Element Models ◽  
Local Models ◽  
Bolted Connections ◽  
The Core ◽  
Potential Failure ◽  
Reactor Internals

Pressurized water reactor (PWR) vessel internals components can experience material aging and degradation due to irradiation [1]. The Electric Power Research Institute (EPRI), under sponsorship of the Materials Reliability Program (MRP), developed PWR Internals Inspection and Evaluation (I&E) Guidelines mainly to support license renewal of U.S. plants [2]. The functionality analysis of reactor internals components and assemblies was one of the tools used to develop these guidelines. The purpose of the functionality analysis is to provide a best estimate evaluation of the reactor internals core barrel assembly for materials degradation and to assess whether the components retain their function. The evaluation uses an irradiated material-specific constitutive model for use in a finite element analysis representing the current state of knowledge for plasticity, creep, stress relaxation, void swelling, and embrittlement [3], 4, [5]. This constitutive model is a function of temperature and fluence. The analysis focuses on finding the integrated effects of material aging combined with steady-state operational characteristics of the reactor vessel (RV) internals. In order to evaluate the potential failure mechanisms of the core barrel assembly, finite element models were developed capable of representing the complex interactions between the components. The goal of this specific analysis is to characterize the potential failure modes, spatial and chronological distribution of potential component failures for a representative model of the Babcock & Wilcox (B&W) designed plants. Evaluation of the reactor vessel internals for materials aging degradation involves three analytical calculations. Radiation calculations of the core provide essential information on radiation dose and heat rates, due to gamma-heating, of the RV internals. The computational fluid dynamics domain (CFD) allows the evaluation of the RV internals temperatures through conjugate heat transfer (CHT) analysis coupled with coolant flow. Detailed structural analysis of the RV internals components and bolted connections is the third major analytical calculation, which facilitates the development of operating stress fields within the RV internals. Structural analysis was performed as two parts. First, a global structural model of the core barrel assembly was used to represent the interaction of components of the core barrel assembly during 60 years of operation. The global model does not include detail of the areas of stress concentration within bolted connections, therefore local models of selected bolts were developed. Results of both the global and local models were used as a basis for evaluating age-related effects. The description of the functionality analysis for the B&W designed RV internals is divided into three papers. Part I was presented in PVP-2008 [6] and included a description of the overall methodology with special attention to CFD-CHT evaluations. Part II, detailed in this paper, describes global structural finite element models. Part III, to be also presented at PVP-2009 [7], presents a description of local models of bolted connections, results, and conclusions.

scholarly journals THE METHOD OF SELECTION THE SOLID FINITE ELEMENT MODELS OF LOAD-BEARING SYSTEMS OF MACHINE TOOLS WHEN PERFORMING ENGINEERING ANALYSIS

2019 ◽  
pp. 102-116
Author(s):  
М. Полоз ◽  
Polina Davidenko ◽  
А. Шевченко ◽  
Andrey Shevchenko ◽  
Е. Ерижокова ◽  
...  
Keyword(s):  
Finite Element ◽  
Computational Model ◽  
Machine Tools ◽  
Design Model ◽  
Design Parameters ◽  
Finite Element Models ◽  
Modeling Error ◽  
Load Bearing ◽  
Ideal Contact ◽  
Bearing System

The paper presents a methodology for the selection of a solid finite element models for load-bearing systems of machine tools. The technique is based on the analysis of the results of computer simulation of different models of load-bearing systems of three machines with different layouts. The variability of the models is determined taking into account the traction devices and joints in the conjunctions. The traditional approach for modeling the non-ideal joint in the form of elastic elements set is used, despite the fact that modern CAE systems for modeling non-ideal contact in mates offer special contact finite elements. The conducted computational experiments demonstrate that the most accurate model is obtained by using models of traction devices and joints. In this case, the computational model requires significant computational resources. It is found that the exception of the design model of the bearing system of the machine traction devices can lead to an increased modeling error in static problems up to 25 %. The results of modal and dynamic calculations are more resistant to changes in the design model of the machine, as the error of the design parameters does not exceed 10 %. In addition, the computational models of tightened joint, with a stiffness of more than N/m, are not much different from models with ideal contact. It is shown that with an acceptable 25% modeling error, it is preferable to use a computational model of the load-bearing system without taking into account the non-ideal contact and traction devices

scholarly journals REALIZATION OF THE RIGID CHARACTERISTICS OF ROLLING RAIL GUIDES OF MACHINE EQUIPMENT

2021 ◽  
Author(s):  
Vladimir Lebedev
Keyword(s):  
Finite Element ◽  
Machine Tools ◽  
Finite Element Models ◽  
Simplified Method ◽  
Stiffness Characteristics

A simplified method of accounting and regulation of the stiffness characteristics of rolling rail guides of machine tools in volumetric finite element models is considered.

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