Simulation of gas quenching

2004 ◽  
Vol 120 ◽  
pp. 727-735
Author(s):  
F. Frerichs ◽  
Th. Lübben ◽  
U. Fritsching ◽  
H. Lohner ◽  
A. Rocha ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Treatment ◽  
Strain Hardening ◽  
Mechanical Behaviour ◽  
Mechanical Response ◽  
Temperature Dependent ◽  
Finite Element Program ◽  
Element Program ◽  
Gas Quenching

The prediction of mechanical behaviour of specimen during heat treatment by means of numerical simulation requires numerous modules e.g. for heat transfer and mechanical behaviour. The quality of predictions depend on the quality of the applied models within the modules. In this paper the strain hardening model used in the mechanical module will be investigated. For simulation of mechanical behaviour during gas quenching it is first of all necessary to calculate the interaction between gas and specimen. Using simulated flow field and temperature distribution within the gas, the heat transfer coefficient is calculated from computational fluid dynamics. The cooling and further the mechanical behaviour e.g. residual stresses and distortion of the specimen are simulated by a commercial Finite Element program. To investigate strain hardening it is helpful to choose in a first step a material that will not show phase transformations due to heat treatment. Therefore simulation of mechanical behaviour of austenitic cylinders (SAE30300) is investigated. The required thermo-physical properties such as thermal conductivity, density, and specific heat are taken from literature. With the exception of Poisson’s ratio the mechanical properties are measured and calculated by own investigations. For description of the temperature dependent stress strain curves the Ramberg-Osgood model is used. The simulated results are compared with experimental data in order to decide which model better describes the mechanical response, whether the kinematic or isotropic strain hardening.

The strain hardening behaviour of particulate media

1976 ◽  
Vol 13 (3) ◽  
pp. 311-323 ◽  
Author(s):  
S. Frydman
Keyword(s):  
Strain Hardening ◽  
Three Dimensional ◽  
Flow Rule ◽  
Finite Element Program ◽  
Particulate Media ◽  
Stress Strain Relation ◽  
Element Program ◽  
Plastic Components ◽  
Associated Flow Rule ◽  
Particulate Medium

The strain increment resulting from an increment of stress applied to a particulate medium has been expressed in terms of its elastic and plastic components. The concepts of strain-hardening plasticity have been employed to develop an incremental stress–strain relation, based on a non-associated flow rule. The parameters appearing in the relation have been found using results of three-dimensional shear tests on sands and glass-microspheres. It is suggested that relations of the type developed in the paper could be beneficially incorporated into a finite-element program.

A Comparative Study of the Response of Double Shearing and Hypoplastic Models

2002 ◽  
Author(s):  
Huaning Zhu ◽  
Morteza M. Mehrabadi ◽  
Mehrdad Massoudi
Keyword(s):  
Cyclic Loading ◽  
Mechanical Response ◽  
Constitutive Relations ◽  
Constitutive Models ◽  
Shear Loading ◽  
Biaxial Compression ◽  
Finite Element Program ◽  
Cyclic Shear ◽  
Hypoplastic Model ◽  
Element Program

The principal objective of this paper is to compare the mechanical response of a double shearing model with that of a hypoplastic model under biaxial compression and under cyclic shear loading. As the origins and nature of these two models are completely different, it is interesting to compare the predictions of these two models. The constitutive relations of the double shearing and the hypoplastic models are implemented in the finite element program ABACUS/Explicit. It is found that the hypoplastic and the double shearing constitutive models both show strong capability in capturing the essential behavior of granular materials. In particular, under the condition of non-cyclic loading, the stress ratio and void ratio predictions of the double shearing and the hypoplastic models are relatively close, while under the condition of cyclic loading, the predictions of these models are quite different. It is important to note that in the double shearing model employed in this comparison the shear rates on the two slip systems are assumed to be equal. Hence, the conclusions derived in this comparison pertain only to this particular double shearing model. Similarly, the hypoplasticity model considered here is that proposed by Wu, et al. [30] and the conclusions reached here pertain only to this particular hypoplasticity model.

Algorithm and Program for Simulating Heat Transfer in Cavities of Structural Members under Fire Conditions

2011 ◽  
Vol 90-93 ◽  
pp. 3227-3233
Author(s):  
Yong Jun Liu ◽  
Dong Wang ◽  
Xing Tao Ma
Keyword(s):  
Heat Transfer ◽  
Heat Flow ◽  
Radiative Heat ◽  
Coefficient Matrix ◽  
System Of Equations ◽  
Structural Members ◽  
Finite Element Program ◽  
Heat Flows ◽  
Element Program ◽  
Fire Conditions

In this paper, an algorithm based on the network method suggested by Oppenheim for calculating the radiative heat flow in a cavity of structural members, say hollow core concrete slabs, exposed to fires is presented. It is assumed that the pressure in a cavity keeps atmospheric pressure through the whole cause of a fire, and the lost heat from the air due to expansion and immediate moving away from a cavity is neglected. The heat in a cavity is transfer via both heat conduction in air and thermal radiation among boundaries, and special regard is paid to modeling heat transfer by radiation. The effective radiative heat flow system of equations is derived and expressed in matrix form. The system of equations features a symmetric coefficient matrix, which can be stored in a one dimensional array, and can be solved using LDLT factorization. Node radiative thermal loads are calculated from effective radiative heat flows at edges of elements located on internal cavities. The nonlinear finite element program TFIELD written by first author has employed the new algorithm. Temperature distribution in two structural members with cavities are calculated using TFIELD, and numerical results demonstrate that the new algorithm is very effective and is useful for further study of structural behavior of structural members under fire conditions.

Numerical Implementation of a Multi-Physical Fields Coupling Constitute Model

2013 ◽  
Vol 457-458 ◽  
pp. 354-357
Author(s):  
Yu Jie Sun ◽  
Qing Chun Cui ◽  
Suo Huai Zhang ◽  
Li Jun Yan
Keyword(s):  
Material Properties ◽  
General Purpose ◽  
Computational Method ◽  
Numerical Implementation ◽  
Temperature Dependent ◽  
Working Process ◽  
Finite Element Program ◽  
Element Program ◽  
User Material Subroutine ◽  
Constitute Model

The objective of this paper provides a numerical implementation procedure of thermo-metallurgical-mechanical constitute equation based on additively decomposition of strain rate. Together with phase transformation kinetics, the macro material properties are determined by assigning temperature dependent material properties to each phase and by applying mixture rule to combine. Then the constitute equation is implemented into general purpose implicit finite element program via user material subroutine. The effectiveness of developed computational method is confirmed by a Satoh test simulation. Simulation of Satoh test demonstrates that transformation induce plasticity has significant effect of the evolution of residual stress and can not be neglected for alloy steel during hot working process.

Analysis of Strain Hardening Behaviour of Cast Aluminium Alloy 354 Subjected to Artificial Ageing at Various Temperatures

2013 ◽  
Vol 856 ◽  
pp. 231-235 ◽  
Author(s):  
Aditya Eswar ◽  
Arnav Gupta ◽  
G. Dinesh Babu ◽  
M. Nageswara Rao
Keyword(s):  
Heat Treatment ◽  
Aluminium Alloy ◽  
Strain Hardening ◽  
Automotive Industry ◽  
Mechanical Behaviour ◽  
Artificial Ageing ◽  
Cast Aluminium ◽  
Heat Treated ◽  
Lower Strain ◽  
Wide Scale

Automotive industry makes wide scale use of cast aluminium alloy 354 in the production of crucial components, such as compressor wheels for turbochargers. The compressor wheels undergo T61 heat treatment, involving artificial ageing at 188°C. This study focuses on the possible improvement of the mechanical behaviour of the components by subjecting them to modified heat treatments involving usage of lower artificial ageing temperatures (160, 171 and 177°C). A comparative analysis of tensile properties and strain hardening behaviour has been carried out with different artificial ageing temperatures. Results showed that the heat treatment routinely employed by the industry (aged at 188°C) leads to overageing, thereby resulting in relatively inferior mechanical properties and lower strain hardening rates as compared to the samples heat treated at lower artificial ageing temperatures. It is concluded that lowering of the artificial ageing temperature can lead to a superior state of components with respect to mechanical behaviour.

Shape and Size Optimization Design of Finned Brass Tube on the Central Air Conditioning

2012 ◽  
Vol 588-589 ◽  
pp. 1854-1857
Author(s):  
Shuang Chen ◽  
Bing Yan Zhang ◽  
Jian Hua Zhong
Keyword(s):  
Heat Transfer ◽  
Transfer Process ◽  
Optimization Design ◽  
Heat Transfer Process ◽  
Finned Tube ◽  
Structure Parameters ◽  
Finite Element Program ◽  
Fin Efficiency ◽  
Heat Transfer Theory ◽  
Element Program

Finned tube heat transfer process was analyzed in this thesis, the optimal mathematical model of the fin efficiency and fin volume which was acted as the objective function is established based on the model of heat transfer theory. The heat exchanger numerical simulation of finned tube is taken by the ANSYS finite element program in heat transfer process, and the finned tube structure parameters ( fin spacing , fin thickness , fin height) were analyzed , the optimum structure parameters of a set of finned tube were obtained at the same time. These studies will have some guidance on the application of finned tubes.

Heat Transfer in Stepped Labyrinth Seals

1988 ◽  
Vol 110 (1) ◽  
pp. 63-69 ◽  
Author(s):  
S. Wittig ◽  
K. Jacobsen ◽  
U. Schelling ◽  
S. Kim
Keyword(s):  
Heat Transfer ◽  
Wall Friction ◽  
Leakage Flow ◽  
Test Rig ◽  
Transfer Coefficients ◽  
Labyrinth Seals ◽  
Finite Element Program ◽  
Heat Transfer Coefficients ◽  
Flow And Heat Transfer ◽  
Element Program

Leakage flow and heat transfer of scaled-up stepped labyrinth seals were investigated experimentally and numerically. The experiments were conducted in a test rig under steady conditions. For different geometries and pressure ratios a finite element program was used to determine the temperature distribution and subsequently the heat transfer coefficients. In verifying the experimental results, the flow field of the seals was calculated numerically by a finite difference program. Heat transfer coefficients were derived utilizing the well-known analogies between heat transfer and wall friction.

Properties of Al-Si-Fe-Cu-Mg Alloy PM Composites Obtained by Closed - Die Forging and Heat Treatment

2010 ◽  
Vol 638-642 ◽  
pp. 1842-1847
Author(s):  
Stefan Szczepanik ◽  
Marek Wojtaszek
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Cross Section ◽  
Bend Strength ◽  
Powder Mixtures ◽  
Finite Element Program ◽  
Die Forging ◽  
Closed Die Forging ◽  
Element Program ◽  
Simulated Distribution

Aluminium RAl-1 and its alloy Al17Si5Fe3Cu1.1Mg0.6Zr composite materials were manufactured from powder mixtures by cold pressing, hot closed-die forging at 480oC and heat treatment. Powders ranging in composition in 20 wt.% steps of the alloy were mixed in a Turbula mixer for 1 h. The preforms with alloy concentrations of 80 and 100 % were hot consolidated at 480oC and closed-die forged at the same temperature. The effect of chemical composition on microstructure and mechanical properties in bending and compression was examined. Bend strength ranged from 400 to 540 MPa, compression strength from 415 to 744 MPa and hardness from 32 to 203 HB. Simulated distribution of component materials for a cross-section of the forging and shapes of the materials were analysed using LARSTRAN/Shape finite element program and are qualitatively comparable with the results obtained by forging.

Modeling Alkali-Silica Reaction Using Image Analysis and Finite Element Analysis

2011 ◽  
Vol 250-253 ◽  
pp. 1050-1053
Author(s):  
Jun Ho Shin ◽  
Nam Yong Jee ◽  
Leslie J. Struble ◽  
R. James Kirkpatrick
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Mechanical Response ◽  
Standard Test ◽  
Alkali Silica Reaction ◽  
Element Analysis ◽  
Finite Element Program ◽  
The Finite Element Analysis ◽  
Element Program ◽  
Element Approach

The objective of this study is to develop a numerical model based on microstructural images of concrete and fundamental material properties of each constituent of concrete subjected to alkali-silica reaction (ASR). A microstructure-based finite element approach is employed directly to analyze the mechanical response of concrete to ASR. The modeling work involves acquiring and processing of microstructural images of specimens suffering from ASR using scanning electron microscopy, and implementing finite element program to analyze the microstructural images. The formulation of this model is based on pressure caused by the ASR product and on properties such as Young’s modulus and Poisson’s ratio. The finite element analysis program used to simulate structural behavior of structures attacked by ASR is object-oriented finite element developed at National Institute of Standards and Technology. The numerical results from this model are compared with experimental data, which have been measured using ASTM standard test C1260. The results show that the development and widening of cracks by formation and swelling of ASR gel cause the majority of expansion of mortar specimens rather than elastic elongation due to gel swelling.

Two‐dimensional terrain correction in magnetotelluric surveys

Geophysics ◽  
1988 ◽  
Vol 53 (6) ◽  
pp. 854-862 ◽  
Author(s):  
Michel Chouteau ◽  
Karl Bouchard
Keyword(s):  
Terrain Correction ◽  
Topographic Effects ◽  
Two Dimensional ◽  
Subsurface Structure ◽  
Finite Element Program ◽  
Practical Procedure ◽  
Topographic Features ◽  
Correction Technique ◽  
Element Program

Field distortions caused by topography hamper the interpretation of magnetotelluric (MT) data. Topographic features that can be simulated by two‐dimensional models seriously affect the H-polarization results. A technique to reduce those effects in MT data uses a finite‐element program to compute correction coefficients. After correction, the resulting data can be interpreted as if they were obtained over a flat surface and depended only on the subsurface structure. The technique is applied to four examples representative of MT survey targets in high‐relief terrain. Results indicate that terrain correction removes the misleading topographic anomalies and improves the quality of subsurface interpretation in regions where the surface relief is two‐dimensional. The correction technique yields some geometrical distortion of the original subsurface structure, but the distortion is usually of small importance. In practice, telluric dipoles of realistic length do not smooth out topographic effects having wavelengths longer than the telluric dipole. A practical procedure derived from the proposed technique allows terrain correction when the relief is approximately two‐dimensional.

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