The Effect of Solution Heat Treatment and Natural Ageing on the Yield Characteristics of a 2024-O Aluminium Alloy

2000 ◽  
Author(s):  
M. T. J. Ashbridge ◽  
A. G. Leacock ◽  
K. R. Gilmour ◽  
M. F. O’Donnell ◽  
D. McDonnell
Keyword(s):  
Heat Treatment ◽  
Finite Element ◽  
Solution Heat Treatment ◽  
Large Scale ◽  
Biaxial Tension ◽  
Yield Criterion ◽  
Deformation Behaviour ◽  
Material Model ◽  
Tensile Tests ◽  
Age Hardening

Abstract Recent advances in computational technology have allowed engineers to conduct previously impractical analyses, particularly with the development of the Finite Element Method (FEM). In turn, this has led the sheet metal forming industry into an economy drive, with an increasing necessity for ‘first time’ forming operations and reduced scrap rates. The successful prediction of large-scale plastic deformation in a sheet component relies on the accuracy of the material model used, especially when anisotropic materials are considered. Some stretch formed or deep drawn forms are geometrically complex and may require several draws with inter-stage anneals and/or solution heat treatments to achieve full form, and the varying material properties create significant difficulties in the modelling of these forming processes. Current orthotropic yield criteria do not allow for any sense of time dependency and although the atomic effects of solution heat treatment and precipitation hardening are well understood, the macroscopic effects of deformation behaviour are not. A test program was developed to investigate the effects of an increasing age hardening time on an aerospace Alclad 2024-O material after a solution heat treatment. With access to industrial heat treatment equipment, extensive tensile tests were conducted at varying age hardening times and a test rig was manufactured to obtain balanced biaxial tension data. Through the subsequent analysis, a method of predicting the data needed to generate a materials model suitable for FEA was developed, based on a modified version of Hill’s 1990 non-quadratic yield criterion. This was used to generate yield loci for the various age hardening times and compared with the loci generated with the predicted loci. Evaluation of the accuracy of the new criterion, and hence the predictive method, was achieved through its implementation in a finite element code used to model a punch-stretch test. Modelled surface strains were then compared with those measured strains determined during an empirical validation test programme. With the knowledge that the analysis came from data predicted from a minimum of empirical tests, the predicted results were found to be in good agreement with the experimental values.

A Rubber Bag for Liquid Cargo to Improve Ship Collision Safety

2016 ◽  
Author(s):  
Jan M. Kubiczek ◽  
Boyuan Liang ◽  
Lars Molter ◽  
Sören Ehlers
Keyword(s):  
Structural Design ◽  
Large Scale ◽  
Material Model ◽  
Tensile Tests ◽  
Additional Increase ◽  
Safety Level ◽  
Oil Leakage ◽  
Collision Safety ◽  
Reaction Forces ◽  
Ship Collision

Collisions and grounding accidents of ships, but also the failure of the hull-integrity, can lead to oil leakage. Examples are the Rena in 2011, the Hebei Spirit in 2007 and the much known accident of the Prestige in 2002. Consequently research regarding the enhancement of the structural design to increase the safety-level of ships in case of accidents is important. In this paper the use of a rubber bag as a second barrier is presented as an alternative concept to prevent oil leakage in case of accidents. The influence of the rubber bag is investigated using the example of a ship collision. A simplified tanker side structure as well as a box shaped rubber bag are analyzed with the finite element method. The material model for the rubber bag is calibrated with tensile tests to obtain the required material parameters. The reaction forces and the associated penetration depth are analyzed. The comparison is done between the structure with and without the rubber bag. For the latter, the general behavior is compared with large-scale experimental results. Furthermore an additional increase of the survivability of the ship due to the rubber bag without changing the common structural design is discussed.

scholarly journals The Effect of Elastic Strain and Small Plastic Deformation on Tensile Strength of a Lean Al–Mg–Si Alloy

Metals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 1276
Author(s):  
Eva Anne Mørtsell ◽  
Ida Westermann ◽  
Calin Daniel Marioara ◽  
Ketill Olav Pedersen ◽  
Sigmund Jarle Andersen ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Plastic Deformation ◽  
Elastic Strain ◽  
Solution Heat Treatment ◽  
Small Deformation ◽  
Age Hardening ◽  
Strength Increase ◽  
Artificial Ageing ◽  
Small Plastic ◽  
Small Plastic Deformation

Al–Mg–Si alloys are usually formed into their final shape by rolling or extrusion. After extrusion, the aluminium profiles are usually straightened, causing the material to be subjected to a small plastic deformation. This study demonstrates the positive effect on strength that can be obtained from such small deformation levels or from only elastically straining the material. Elastic straining of a lean Al–Mg–Si alloy, when performed immediately after solution heat treatment, enhances the material yield strength after artificial ageing to T6. Transmission electron microscopy shows that this effect can be attributed to a higher number density and finer dispersion of the age-hardening precipitate needles. Furthermore, introducing a small plastic deformation of 1% after solution heat treatment results in a comparable strength increase to elastically straining the material. In this case, however, the strength increase is due to the increased dislocation density, which compensates for a lower density of precipitate needles. Finally, by combining plastic deformation with a succeeding elastic strain, we demonstrate how elastic strain can cause an on-set of dislocation cell formation in this material.

Prediction of Cutting Force in Bone Cutting Using Finite Element Analysis

2021 ◽  
Author(s):  
Varatharajan Prasannavenkadesan ◽  
Ponnusamy Pandithevan
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Cutting Force ◽  
Material Model ◽  
Tensile Tests ◽  
Bovine Bone ◽  
Element Analysis ◽  
Cutting Processes ◽  
Parameter Values ◽  
First Time

Abstract In orthopedic surgery, bone cutting is an indispensable procedure followed by the surgeons to treat the fractured and fragmented bones. Because of the unsuitable parameter values used in the cutting processes, micro crack, fragmentation, and thermal osteonecrosis of bone are observed. Therefore, prediction of suitable cutting force is essential to subtract the bone without any adverse effect. In this study, the Cowper-Symonds model for bovine bone was developed for the first time. Then the developed model was coupled with the finite element analysis to predict the cutting force. To determine the model constants, tensile tests with different strain rates (10−5/s, 10−4/s, 10−3/s, and 1/s) were conducted on the cortical bone specimens. The developed material model was implemented in the bone cutting simulation and validated with the experiments.

Fatigue Behavior of Age-Hardening Cu-6Ni-1.5Si Alloys with Different Grain Sizes

2021 ◽  
Vol 1016 ◽  
pp. 125-131
Author(s):  
Masahiro Goto ◽  
T. Yamamoto ◽  
S.Z. Han ◽  
J. Kitamura ◽  
J.H. Ahn ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Grain Size ◽  
Fatigue Strength ◽  
Solution Heat Treatment ◽  
Fatigue Behavior ◽  
Fatigue Tests ◽  
The Other ◽  
Age Hardening ◽  
Grain Sizes ◽  
Thermomechanical Processes

On the thermomechanical treatments of Cu-Ni-Si alloy, cold-rolling (CR) before solution heat treatment (SHT) is commonly conducted to eliminate defects in a casting slab. In addition, a rolling is applied to reduce/adjust the thickness of casting slab before SHT. In a heavily deformed microstructure by CR, on the other hand, grain growth during a heating in SHT is likely to occur as the result of recrystallization. In general, tensile strength and fatigue strength tend to decrease with an increase in the grain size. However, the effect of difference in grain sizes produced by with and without CR before SHT on the fatigue strength is unclear. In the present study, fatigue tests of Cu-6Ni-Si alloy smooth specimens with a grain fabricated through different thermomechanical processes were conducted. The fatigue behavior of Cu-Ni-Si alloy was discussed.

scholarly journals A Phenomenological Mechanical Material Model for Precipitation Hardening Aluminium Alloys

Metals ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 1165 ◽  
Author(s):  
Hannes Fröck ◽  
Lukas Vincent Kappis ◽  
Michael Reich ◽  
Olaf Kessler
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Finite Element ◽  
Phase Transformation ◽  
Aluminium Alloys ◽  
Material Model ◽  
Heat Treatments ◽  
Maximum Temperature ◽  
Finite Element Software ◽  
Welding Processes

Age hardening aluminium alloys obtain their strength by forming precipitates. This precipitation-hardened state is often the initial condition for short-term heat treatments, like welding processes or local laser heat treatment to produce tailored heat-treated profiles (THTP). During these heat treatments, the strength-increasing precipitates are dissolved depending on the maximum temperature and the material is softened in these areas. Depending on the temperature path, the mechanical properties differ between heating and cooling at the same temperature. To model this behavior, a phenomenological material model was developed based on the dissolution characteristics and experimental flow curves were developed depending on the current temperature and the maximum temperature. The dissolution characteristics were analyzed by calorimetry. The mechanical properties at different temperatures and peak temperatures were recorded by thermomechanical analysis. The usual phase transformation equations in the Finite Element Method (FEM) code, which were developed for phase transformation in steels, were used to develop a phenomenological model for the mechanical properties as a function of the relevant heat treatment parameters. This material model was implemented for aluminium alloy 6060 T4 in the finite element software LS-DYNA (Livermore Software Technology Corporation).

scholarly journals Development of Precipitation Hardening Parameters for High Strength Alloy AA 7068

Materials ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 918
Author(s):  
Julia Osten ◽  
Benjamin Milkereit ◽  
Michael Reich ◽  
Bin Yang ◽  
Armin Springer ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Cooling Rate ◽  
Maximum Yield ◽  
High Strength ◽  
Tensile Tests ◽  
Age Hardening ◽  
Scanning Calorimetry ◽  
Cooling Rates ◽  
Critical Cooling Rate ◽  
Kinetics Of

The mechanical properties after age hardening heat treatment and the kinetics of related phase transformations of high strength AlZnMgCu alloy AA 7068 were investigated. The experimental work includes differential scanning calorimetry (DSC), differential fast scanning calorimetry (DFSC), sophisticated differential dilatometry (DIL), scanning electron microscopy (SEM), as well as hardness and tensile tests. For the kinetic analysis of quench induced precipitation by dilatometry new metrological methods and evaluation procedures were established. Using DSC, dissolution behaviour during heating to solution annealing temperature was investigated. These experiments allowed for identification of the appropriate temperature and duration for the solution heat treatment. Continuous cooling experiments in DSC, DFSC, and DIL determined the kinetics of quench induced precipitation. DSC and DIL revealed several overlapping precipitation reactions. The critical cooling rate for a complete supersaturation of the solid solution has been identified to be 600 to 800 K/s. At slightly subcritical cooling rates quench induced precipitation results in a direct hardening effect resulting in a technological critical cooling rate of about 100 K/s, i.e., the hardness after ageing reaches a saturation level for cooling rates faster than 100 K/s. Maximum yield strength of above 600 MPa and tensile strength of up to 650 MPa were attained.

Precipitate and Age Hardening Response of As-Cast Mg-8Yb-0.5Zr Magnesium Alloy

2011 ◽  
Vol 399-401 ◽  
pp. 17-20
Author(s):  
Wen Bin Yu ◽  
Zhi Qian Chen ◽  
Mang Zhang ◽  
Zhou Yu
Keyword(s):  
Heat Treatment ◽  
Magnesium Alloy ◽  
Grain Boundaries ◽  
Microstructure Evolution ◽  
Solution Heat Treatment ◽  
Artificial Aging ◽  
Precipitation Hardening ◽  
Intermetallic Phase ◽  
Age Hardening ◽  
Maximum Hardness

The precipitation hardening response of as-cast Mg-8Yb-0.5Zr magnesium alloy was investigated in the present work. The microstructure evolution of the alloy illustrated that Mg2Yb intermetallic phase was dissolved by solution heat treatment at 520°C for 12 hours. An apparent precipitation hardening response in Mg-8Yb-0.5Zr was discovered after artificial aging at 150°C, with maximum hardness increment of about 80 percent at the peak condition. It was found that the precipitates of the alloy were in the shape of two conjoined cosh and globe about 50 nm, and precipitated preferentially on grain boundaries and dislocations.

BIOMECHANICAL BEHAVIOUR OF BOVINE SKIN: AN EXPERIMENT-THEORY INTEGRATION AND FINITE ELEMENT SIMULATION

2015 ◽  
Vol 76 (10) ◽  
Author(s):  
Nor Fazli Adull Manan ◽  
Jamaluddin Mahmud ◽  
Aidah Jumahat
Keyword(s):  
Finite Element ◽  
Finite Element Simulation ◽  
Deformation Behaviour ◽  
Element Model ◽  
Tensile Tests ◽  
Theory Integration ◽  
Element Simulation ◽  
Knowledge Enhancement ◽  
First Time

This paper for the first time attempts to establish the biomechanical characteristics of bovine skin via experiment-theory integration and finite element simulation. 30 specimens prepared from fresh slaughtered bovine were uniaxially stretched in-vitro using tensile tests machine. The experimental raw data are then input into a Matlab programme, which quantified the hyperelastic parameters based on Ogden constitutive equation. It is found that the Ogden coefficient and exponent for bovine skin are μ = 0.017 MPa and α = 11.049 respectively. For comparison of results, the quantified Ogden parameters are then input into a simple but robust finite element model, which is developed to replicate the experimental setup and simulate the deformation of the bovine skin. Results from experiment-theory integration and finite element simulation are compared. It is found that the stress-stretch curves are close to one another. The results and finding prove that the current study is significant and has contributed to knowledge enhancement about the deformation behaviour of bovine skin.

Computer Aided Modeling of Deep-Drawing

2007 ◽  
Vol 344 ◽  
pp. 341-348
Author(s):  
Mehmet Ali Pişkin ◽  
Bilgin Kaftanoğlu
Keyword(s):  
Finite Element ◽  
Deep Drawing ◽  
Plastic Material ◽  
Yield Criterion ◽  
Shell Element ◽  
Material Model ◽  
Industrial Applications ◽  
Finite Element Program ◽  
Element Program ◽  
Von Mises

Deep-drawing operations are performed widely in industrial applications. It is very important for efficiency to achieve parts with no defects. In this work, a finite element method is developed to simulate deep-drawing operation including wrinkling. A four nodded five degree of freedom shell element is formulated. Isotropic elasto-plastic material model with Von Mises yield criterion is used. By using this shell element, the developed code can predict the bending behavior of workpiece besides membrane behavior. Simulations are carried out with four different element sizes. The thickness strain and nodal displacement values obtained are compared with results of a commercial finite element program and results of previously conducted experiments.

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