scholarly journals A 3-D FINITE ELEMENT FEW-GROUP DIFFUSION CODE AND ITS APPLICATION TO GENERATION IV REACTOR CONCEPTS

2021 ◽  
Vol 247 ◽  
pp. 02010
Author(s):  
A. Seubert
Keyword(s):  
Finite Element ◽  
Medium Size ◽  
Block Type ◽  
Space Applications ◽  
Thermally Induced ◽  
Irregular Geometries ◽  
Regular Lattices ◽  
High Temperature Reactor ◽  
Industrial Regions ◽  
Eu Project

In this paper, a recently developed 3-d few-group finite element-based diffusion code is de-scribed. Its geometrical flexibility allows future modeling of complex and irregular geometries of (very) small and medium size reactor concepts –(v)SMRs –being in the spotlight for energy provision in remote residential and industrial regions or for space applications, and also liquid metal cooled Generation IV reactors where thermally induced core deformation results in localized assembly lattice distortions which cannot be treated by traditional 3-d neutron kinetics codes devoted to the regular lattices of LWR and Generation IV systems. The description of the implemented FEM solution method is followed by first applications to a prismatic (or block type) high-temperature reactor MHTGR-350MW within an OECD/NEA benchmark activity and to the sodium cooled fast reactor concept ASTRID within the past EU project ESNII+. Finally, an outlook to planned further code development activities is given.

Research on Thermally Induced Deformation of Reinforcing Plate Based on Finite Element Simulation

2012 ◽  
Vol 197 ◽  
pp. 139-143
Author(s):  
Hua Bai ◽  
Yi Du Zhang
Keyword(s):  
Finite Element ◽  
Ambient Temperature ◽  
Finite Element Simulation ◽  
Temperature Change ◽  
Large Scale ◽  
Machining Process ◽  
Reinforcement Structure ◽  
Thermally Induced ◽  
Finite Element Software ◽  
Element Simulation

The change of ambient temperature will cause deformation during the machining process of large-scale aerospace monolithic component. Based on finite element simulation, thermally induced deformation of reinforcing plate is studied in such aspects as reinforcement structure, clamping method and temperature change, and contact function in finite element software is used to simulate the unilateral constraint between workpiece and worktable. The results indicate that reinforcing plate will produce warping deformation due to the change of ambient temperature. Different reinforcement structures and clamping methods have important influence on the deformation positions and degrees, and the deformation is proportional to the temperature change.

Reduced Order Finite Element Modeling of Thermally Induced Bearing Loads in Machine Tool Spindles

1999 ◽  
Author(s):  
Alex O. Gibson ◽  
Jeffrey L. Stein
Keyword(s):  
Finite Element ◽  
Thermal Expansion ◽  
Machine Tool ◽  
Mechanical Load ◽  
Machining Process ◽  
Thermally Induced ◽  
Reduced Order ◽  
Wide Range ◽  
Bearing Load ◽  
Bearing Loads

Abstract Machine tool spindle bearings are subjected to a large range of axial and radial loads due to the machining process. Further the rotating spindle must be extremely stiff to minimize the cutting tool’s deflection. The high spindle stiffness is achieved by applying a mechanical load to the bearings, the preload. In fixed preload spindles the bearing loads tend to increase with increasing spindle speed due to thermal expansion and it is well established that these thermally induced loads can lead to premature bearing failure. A model of thermally induced bearing load in angular contact bearing spindles is developed that includes an axis-symmetric reduced order finite element model of the heat transfer and thermal expansion within the spindle’s housing and shaft and the bearing and shaft dynamics. Nodal reduction is used in the reduced order model to minimize the number of temperature states and the computational load. The reduced order model’s calculated temperature and bearing load values are shown to closely match experimentally measured values over a wide range of spindle speeds. The paper ends with a parameter variation study which predicts a dramatic decrease in the thermally induced bearing load when silicon nitride balls are substituted for steel balls.

A Novel Approach for Designing Boltless Connectors - Example on a New Drilling Riser Connector

2021 ◽  
Author(s):  
Eleonore Roguet ◽  
Emmanuel Persent ◽  
Daniel Averbuch
Keyword(s):  
Finite Element ◽  
Design Process ◽  
Load Transfer ◽  
Design Method ◽  
Experimental Tests ◽  
New Product ◽  
Block Type ◽  
Finite Element Analyses ◽  
Novel Approach ◽  
Structural Tests

Abstract A new method which uses elastic and elasto-plastic Finite Element analyses is developed to design a double breech-block type connector. All relevant criteria proposed by API16F are fulfilled. In addition, plastic and bearing criteria have been added to support the use of lugs for load transfer in the connector. The proposed methodology has been applied and validated through experimental tests at different scales and in particular on laboratory specimens and small-scaled connectors. Based on these last structural tests, a safety factor of almost 8 was obtained for the design method on small-scaled connectors. Prototype tests at scale 1:1 allowed the methodology to be fully validated and a new product to be qualified. Certification bodies validated the whole design process, the employed methodology and the new connector.

Control of Static Shape, Dynamic Oscillation, and Thermally Induced Vibration of Nozzles

2005 ◽  
Vol 128 (3) ◽  
pp. 357-363 ◽  
Author(s):  
D. W. Wang ◽  
H. S. Tzou ◽  
S. M. Arnold ◽  
H.-J. Lee
Keyword(s):  
Finite Element ◽  
Conical Shell ◽  
Shape Control ◽  
Numerical Data ◽  
Analysis Data ◽  
Mode Shapes ◽  
Thermal Excitation ◽  
Thermally Induced ◽  
Control Effectiveness ◽  
And Control

Static shape actuation and dynamic control of nozzles can improve their performance, accuracy, reliability, etc. A new curved laminated piezothermoelastic hexahedral finite element is formulated based on the layerwise constant shear angle theory and it is used for modeling and analysis of piezothermoelastic conical shell structures subjected to control voltages for static shape actuation and dynamically and thermally induced vibration controls. Free vibration characteristics of an elastic truncated conical shell nozzle with fixed-free boundary conditions are studied using the new finite element. Both frequencies and mode shapes are accurately computed and compared favorably with available experimental and other numerical data. This study is then extended to evaluate control effectiveness of the conical shell with laminated piezoelectric layers. Static shape control is achieved by an applied electric potential. Vibration sensing and control are carried out using the negative velocity control scheme. Control of thermal excitation is also investigated. Analysis data suggest that the dynamic behavior and control characteristics of conical shells are quite complicated due to the coupled membrane and bending effects participating in the responses. To improve control effectiveness, segmentation and/or shaping of sensor and actuator layers need to be further investigated.

Prediction of Thermal Displacements in Finite Element Tool Models

2001 ◽  
Author(s):  
Jörg Aßmus ◽  
Niels Wessel ◽  
Jürgen Kurths ◽  
Frank Weidermann ◽  
Jan Konvicka ◽  
...  
Keyword(s):  
Finite Element ◽  
Stable Process ◽  
Real Data ◽  
Thermal Displacement ◽  
Thermally Induced ◽  
The Past ◽  
Alternating Conditional Expectation ◽  
Thermal Displacements ◽  
Displacement Based ◽  
Ace Algorithm

Abstract Precision and productivity are very important criteria for the evaluation of modular tool systems and require a thermally stable process with tolerances in the micrometer range. During the past decades there has been an increasing interest in compensating thermally induced errors. In this paper we investigate wheather a prediction of thermal displacement based on a nonlinear regression analysis is possible, namely using the alternating conditional expectation algorithm (ACE) introduced by Breiman and Friedman, 1985. The data we are analyzing were generated by two different finite element spindle models of modular tool systems. As the main result we find that the ACE-algorithm is a powerful tool to model the relation between temperatures and displacements. It could also be a promising approach to handle well-known hysteresis effects. Limitations of this study are the model restricted results, next our findings have to be validated on real data.

Failure Prediction of Flip Chip Packages Using Finite Element Technique

2002 ◽  
Author(s):  
Abm Hasan ◽  
H. Mahfuz ◽  
M. Saha ◽  
S. Jeelani
Keyword(s):  
Finite Element ◽  
Flip Chip ◽  
Thermal Loading ◽  
Failure Modes ◽  
Element Model ◽  
Thermally Induced ◽  
Operational Life ◽  
Flip Chip Assembly ◽  
The Individual ◽  
Element Technique

Flip-chip electronic package undergoes thermal loading during its curing process and operational life. Due to the thermal expansion coefficient (CTE) mismatch of various components, the flip-chip assembly experiences various types of thermally induced stresses and strains. Experimental measurement of these stresses and strains is extremely tedious and rigorous due to the physical limitations in the dimensions of the flip-chip assembly. While experiments provide accurate assessment of stresses and strains at certain locations, a parallel finite element (FE) analysis and analytical study can complementarily determine the displacement, strain and stress fields over the entire region of the flip-chip assembly. Such combination of experimental, finite element and analytical studies are ideal to yield a successful stress analysis of the flip-chip assembly under the various loading conditions. In this study, a two-dimensional finite element model of the flip-chip consisting of the silicon chip, underfill, solder ball, copper pad, solder mask and substrate has been developed. Various stress components under thermal loading condition ranging from −40°C to 150°C have been determined using both the finite element and analytical methods. Stresses such as (σ11, σ12, ε12 etc. are extracted and analyzed for the individual components as well as the entire assembly, and the weakest positions of the flip-chip have been discovered. Detailed description of FE modeling is presented and the different failure modes of chip assembly are discussed.

A numerical simulation for prediction of thermal ablation in composite rocket motor casing

2020 ◽  
pp. 2050020
Author(s):  
Vijaya Kanth Pamarthi ◽  
V. Balakrishna Murthy
Keyword(s):  
Finite Element ◽  
Thermal Protection ◽  
Rocket Motor ◽  
Heat Of Fusion ◽  
Space Applications ◽  
Combustion Gases ◽  
Finite Element Software ◽  
Element Simulation ◽  
Similar Motor ◽  
Insulation Liner

Thermal protection systems (TPS) are used in space applications to protect structures failing from burning and/or excessive temperatures. In this work, a finite element simulation is performed to analyze the behavior of a composite rocket motor casing during the expansion of combustion gases inside the motor. A two-dimensional axisymmetric model of a rocket motor casing provided with an insulating liner is modeled in a finite element software ANSYS. Variable equivalent heat flux at the inside faces of the liner, due to radiation and convection of gases, is estimated and applied as a boundary condition. The reduction of heat load with time due to latent heat of fusion and the resistance offered by char that exists above the pyrolysis front is also considered. At the same time, the material properties of the portion of the liner exposed to its melting point temperature are regulated to offer negligible resistance to move the boundary load on to the pyrolysis front at every instant. A transient analysis is carried out with appropriate mesh quality and time steps for 10 s. Ablation, charring, and unaffected regions are identified and the required insulation liner thickness is recommended. Extension of the procedure to model a similar motor with any other cylindrical length is discussed.

Thermally induced vibration of thin laminated plates by finite element method

1992 ◽  
Vol 42 (1) ◽  
pp. 117-128 ◽  
Author(s):  
Chang Jeng-Shian ◽  
Wang Jiunn-Hsiung ◽  
Tsai Tseng-Zong
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Laminated Plates ◽  
Thermally Induced ◽  
Element Method

Analytical evaluation of thermally induced residual stresses in ground components

2003 ◽  
Vol 217 (5) ◽  
pp. 471-482 ◽  
Author(s):  
D G Walsh ◽  
A A Torrance ◽  
J Tiberg
Keyword(s):  
Experimental Data ◽  
Finite Element ◽  
Critical Temperature ◽  
Yield Strength ◽  
Residual Stresses ◽  
Material Properties ◽  
Analytical Evaluation ◽  
Simple Method ◽  
Thermally Induced

Although thermally induced tensile residual stresses have been known to occur in ground components, it has not been possible to predict the critical temperature at which these stresses begin to manifest themselves in the workpiece. In this paper, a model of the formation of thermally induced tensile residual stresses is proposed and a simple method of calculating the critical temperature above which tensile residual stresses occur is developed. The analysis makes use of dimensional methods to characterize the critical temperature. In addition, a formula characterizing the yield strength as a function of temperature was developed. The model was then validated using finite element techniques and some experimental data. The analysis reveals that it is possible to determine the critical temperature above which tensile residual stresses will be manifested based on readily available material properties. A case study illustrates the application of the technique.

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