Influence of Yield Criteria on the Prediction of Shear Localization Considering the Inhomogeneous Distribution of Microstructure

2004 ◽  
Author(s):  
Xinjian Duan ◽  
Don Metzger ◽  
Mukesh Jian
Keyword(s):  
Aluminium Alloys ◽  
Solid Mechanics ◽  
Large Strain ◽  
Shear Localization ◽  
Al Alloys ◽  
New Approach ◽  
Yield Criteria ◽  
Hardening Law ◽  
Microstructural Inhomogeneity ◽  
Von Mises

The occurrence of shear localization in structural materials is often associated with bifurcation in continuum solid mechanics. Many approaches such as J2 corner theory and the void model have been proposed to simulate this phenomenon by the use of FEM. In this paper, a new approach with a basis in microstructural inhomogeneity has been proposed and successfully applied to simulate large strain deformation in uniaxial tension of aluminium alloys. The method, in addition, takes advantage of a more suitable hardening law for Al alloys — namely the Voce equation. Further, the influence of various yield criteria (i.e. von Mises, Hill’s 1948 and Barlat’s 1991) on the prediction of shear localization is discussed in the present work. The predicted shear band angle is also compared with the measured value.

A New Approach to Refine Grains in Al Alloys

2014 ◽  
Vol 17 (6) ◽  
pp. 796-801 ◽  
Author(s):  
Zhihao Bai ◽  
Feng Qiu ◽  
Tao Zhang ◽  
Qichuan Jiang
Keyword(s):  
Al Alloys ◽  
New Approach

Formability Analysis of Fukui Stretch-Drawing and Square Cup Drawing Using Strain and Stress Based Forming Limit Curves

2017 ◽  
Vol 751 ◽  
pp. 167-172 ◽  
Author(s):  
Sansot Panich ◽  
Nopparat Seemuang ◽  
Taratip Chaimongkon
Keyword(s):  
Flow Behavior ◽  
High Strength ◽  
Forming Limit ◽  
Forming Limit Curve ◽  
Yield Criteria ◽  
Hardening Law ◽  
Stress Curve ◽  
Strain Paths ◽  
Cup Drawing ◽  
Better Than

In this work, the experimental and numerical analyses of Forming Limit Curve (FLC) and Forming Limit Stress Curve (FLSC) for Advanced High Strength Steel (AHSS) sheet, grade JAC780Y, are performed. Initially, the FLC is experimentally determined by means of the Nakazima Stretch forming test. Subsequently, the FLSC of investigated steel was plastically calculated using the experimental FLC data. Different yield criteria including Hill48, and Yld89, are applied to describe plastic flow behavior of the AHS steel and Swift hardening law is taken into account. Hereby, influences of the constitutive yield models on the numerically determined FLSCs are evaluated regarding to those results from the experimental data. The obtained stress based forming limits are affected significantly by the yield criteria. Finally, the experimental and numerical formability analyses of Fukui stretch-drawing and square cup drawing tests are studied through FLC and FLSCs. It is observed that all stress based curves can be used very well to describe material formability of the examined steel compared to the strain based FLC. The strain based FLC depend on forming history and strain paths change. In the other hand, the stress based FLC do not depend on these issue. In this study, it can be concluded that the FLSCs could predict failure more realistically and better than the strain based FLC.

scholarly journals Influence of Wind Speed, Wind Direction and Turbulence Model for Bridge Hanger: A Case Study

Symmetry ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1633
Author(s):  
Yang Ding ◽  
Shuang-Xi Zhou ◽  
Yong-Qi Wei ◽  
Tong-Lin Yang ◽  
Jing-Liang Dong
Keyword(s):  
Wind Speed ◽  
Wind Direction ◽  
Wind Field ◽  
Solid Mechanics ◽  
Von Mises Stress ◽  
Long Span Bridges ◽  
High Rise ◽  
Long Span ◽  
Cfd Models ◽  
Von Mises

Wind field (e.g., wind speed and wind direction) has the characteristics of randomness, nonlinearity, and uncertainty, which can be critical and even destructive on a long-span bridge’s hangers, such as vortex shedding, galloping, and flutter. Nowadays, the finite element method is widely used for model calculation, such as in long-span bridges and high-rise buildings. In this study, the investigated bridge hanger model was established by COMSOL Multiphysics software, which can calculate fluid dynamics (CFD), solid mechanics, and fluid–solid coupling. Regarding the wind field of bridge hangers, the influence of CFD models, wind speed, and wind direction are investigated. Specifically, the bridge hanger structure has symmetrical characteristics, which can greatly reduce the calculation efficiency. Furthermore, the von Mises stress of bridge hangers is calculated based on fluid–solid coupling.

Response, Localization, and Rupture of Anisotropic Tubes Under Combined Pressure and Tension

2020 ◽  
Vol 88 (1) ◽  
Author(s):  
Martin Scales ◽  
Kelin Chen ◽  
Stelios Kyriakides
Keyword(s):  
Constitutive Model ◽  
Ductile Failure ◽  
Failure Criteria ◽  
Yield Function ◽  
Local Deformation ◽  
Al Alloys ◽  
Biaxial Stress ◽  
Image Correlation ◽  
Element Analysis ◽  
Von Mises

Abstract The inelastic response and failure of Al-6061-T6 tubes under combined internal pressure and tension is investigated as part of a broader study of ductile failure of Al-alloys. A custom experimental setup is used to load thin-walled tubes to failure under radial paths in the axial-hoop stress space. All loading paths achieve nominal stress maxima beyond which deformation localizes into a narrow band. 3D digital image correlation (DIC) was used to monitor the deformations in the test section and successfully captured the rapid growth of strain within the localization bands where they burst. The biaxial stress states generated are first used to calibrate the nonquadratic anisotropic Yld04-3D yield function (Barlat et al., 2005, “Linear Transformation-based Anisotropic Yield Functions,” Int. J. Plasticity, 21(5), pp. 1009–1039). The constitutive model is then incorporated through a UMAT into a finite element analysis and used to simulate numerically the experiments. The same calculations were performed using von Mises (VM) and an isotropic nonquadratic yield function. The material hardening responses adopted were extracted for each constitutive model from the necked zone of a tensile test using an inverse method. The use of solid elements captures the evolution of local deformation deep into the localizing part of the response, producing strain levels that are required in the application of failure criteria. The results demonstrate that the adoption of a nonquadratic yield function, together with a correct material hardening response are essential for large deformation predictions in localizing zones in Al-alloys. Including the anisotropy in such a constitutive model produces results that are closest to the experiments.

Improving Prediction of Limit Bending Load for Wall-Thinned Pipes by Reconsidering the Effect of Biaxiality

2015 ◽  
Author(s):  
Kosuke Mori ◽  
Toshiyuki Meshii
Keyword(s):  
Finite Element Analysis ◽  
Large Strain ◽  
Axial Stress ◽  
Plastic Instability ◽  
Failure Criteria ◽  
Von Mises Stress ◽  
Element Analysis ◽  
Crack Penetration ◽  
Bending Load ◽  
Von Mises

In this paper, a failure criterion applicable to large-strain finite element analysis (FEA) results was studied to predict the limit bending load Mc of the groove shaped wall-thinned pipes, under combined internal pressure and bending load, that experienced cracking. In our previous studies, Meshii and Ito [1] considered cracking of pipes with groove shaped flaw (small axial length δz in Fig. 1) was due to the plastic instability at the wall-thinned section and proposed the Domain Collapse Criterion (DCC). The DCC predicted Mc of cracking for small δz by comparing the von Mises stress σMises with the true tensile strength σB. However, it was indicated that the predictability of Mc was not necessarily sufficient. Thus, in this work, attempts were made to improve the accuracy of Mc prediction with a perspective that multi-axial stress state might affect this plastic instability. As a result of examination of the various failure criteria based on multi-axial stress, it was confirmed that the limit bending load of the groove flawed pipe that experienced cracking could be predicted within 5 % accuracy by applying Hill’s plastic instability onset criterion [2] to the outer surface of the crack penetration section. The accuracy of the predicted limit bending load was improved from DCC’s error of 15% to 5%.

In-Plane Plane-Strain Formability Investigation of Friction Stir Welded Sheets Made of Dissimilar Aluminium Alloys

2013 ◽  
Vol 446-447 ◽  
pp. 301-305
Author(s):  
Mukesh Kumar ◽  
Satish V. Kailas ◽  
R. Ganesh Narayanan
Keyword(s):  
Plane Strain ◽  
Heat Input ◽  
Rotational Speed ◽  
Aluminium Alloys ◽  
Traverse Speed ◽  
Al Alloys ◽  
Welding Parameters ◽  
Strain Hardening Exponent ◽  
Friction Stir ◽  
Shoulder Diameter

In the present work, the influence of shoulder diameter, traverse speed, and rotational speed on the formability of friction stir welded sheets made between sheets of AA6061T6 and AA5052H32 Al alloys has been studied. In-Plane Plane-Strain formability tests are conducted for this purpose. It is understood from the results that the formability of welded sheets can be improved by optimizing the welding and tool parameters. A larger shoulder diameter, higher traverse speed, and lower rotational speed are favorable for improved formability, and strain hardening exponent of weld region. This is due to the fact that the heat input and subsequent microstructure evolved depends on the heat input, which depends on the welding parameters.

Properties of Aluminium Alloys Produced by Selective Laser Melting

2016 ◽  
Vol 710 ◽  
pp. 83-88 ◽  
Author(s):  
Paola Bassani ◽  
Carlo Alberto Biffi ◽  
Riccardo Casati ◽  
Adrianni Zanatta Alarcon ◽  
Ausonio Tuissi ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Additive Manufacturing ◽  
Selective Laser Melting ◽  
Aluminium Alloys ◽  
Al Alloys ◽  
Laser Melting ◽  
Microstructural Refinement ◽  
Manufacturing Techniques

Analysis of peculiar properties offered by Al alloys produced according to additive manufacturing techniques, specifically by Selective Laser Melting (SLM), is carried out. Two alloys are considered, derived by casting (AlSi10Mg) and by wrought (ENAW 2618) applications. The SLM processed samples are investigated considering their microstructural and mechanical properties after SLM and compared to cast and wrought counterparts. A strong microstructural refinement induced by SLM processing is observed for both alloys, resulting in excellent hardness properties. Investigation on integrity of samples revealed that small-size microvoids and unmelted regions could be present in SLM parts.

Design and comparative strength analysis of wheel rims of a lightweight electric vehicle using Al6063 T6 and Al5083 aluminium alloys

2020 ◽  
Vol 2 (99) ◽  
pp. 57-63
Author(s):  
T.B. Korkut ◽  
E. Armakan ◽  
O. Ozaydin ◽  
K. Ozdemir ◽  
A. Goren
Keyword(s):  
Energy Consumption ◽  
Electric Vehicle ◽  
Aluminium Alloys ◽  
Equivalent Stress ◽  
Energy Criterion ◽  
The Body ◽  
Strength Analysis ◽  
Element Analysis ◽  
Safety Belts ◽  
Von Mises

Purpose: Use of aluminium alloys in critical parts of a vehicle is common since they can combine the two important properties of a material those are being strength and lightweight. The aim in this research is to guide to design process of a wheel with taking example of an electric race vehicle implementation. Design/methodology/approach: In this study, the fatigue strengths of wheels produced for a two-person racing electric vehicle (Demobil09) are evaluated by calculating maximum distortion energy criterion (Von Mises) with Finite Element Analysis. Findings: Aluminium alloy wheels are crucial safety related components and are subjected to static and dynamic loads directly. Using FEA results, the weight and equivalent stress of the wheel are both reduced. So, the energy consumption is also decreased. Modal frequencies of the wheel models are determined. Research limitations/implications: In this paper, the materials analysed are AL6063 T6 and Al5083 aluminium alloys. Different materials can be analysed in future works. Practical implications: This paper is focusing on how to reduce the energy consumption of a two-person electric vehicle concentrating on reducing the weight of vehicle wheels. The vehicle is more technological than mass production cars since it is an electric race car which uses a hub motor, the body and chassis are produced using carbon polymer composites and all electronic units are designed and produced. Although its specialities it has homologated safety equipment like seats and safety belts. Originality/value: All boundary conditions must be analysed in details and a strength analysis must be conducted during design of the wheels for different load cases to ensure the strength of a wheel while keeping the weight as low as possible. In this complex process, this paper can give some clues to designers for strengths and weights of the designs since three different wheel forms are evaluated for reducing energy consumption of the vehicle.

A New Approach to Turbulence

1997 ◽  
Vol 12 (18) ◽  
pp. 3121-3152 ◽  
Author(s):  
V. M. Canuto ◽  
M. S. Dubovikov
Keyword(s):  
Present Model ◽  
Large Strain ◽  
General Structure ◽  
Nonlinear Interactions ◽  
Closed Set ◽  
New Approach ◽  
Overall Performance ◽  
Sweeping Effect ◽  
Shear Driven Flows ◽  
Kolmogorov Constant

We propose a closed set of dynamic equations to describe turbulence. The equations are the result of systematic and heuristic elements. Specifically, the UV part of the nonlinear interactions, represented by a dynamical viscosity, is computed for a stirring force of a particular nature. However, since the results exhibit a general structure, we suggest heuristically to extend them to arbitrary flows. Because of nonrenormalizable divergences, the IR part of the nonlinear interactions has constituted a serious problem. We suggest a heuristic model, the basic ingredient of which is that the transfer of energy among eddies is mostly a local process. We show that possible adjustable parameters are actually fixed by the model itself. Because of the heuristic nature of one part of the model, its overall validity rests largely on the accumulated evidence gathered from checking its predictions against data from a wide variety of flows. The model has been tested against more than seventy turbulence statistics for homogeneous isotropic and anisotropic flows (the Kolmogorov constant is predicted to be Ko = 5/3). The overall performance is good. Here, we first extend the model to inhomogeneous flows and test the predictions using the newest laboratory and DNS data on turbulent convection at large Ra (Rayleigh number). The model reproduces both types of data quite accurately. Second, we study the problem of the so-called "sweeping effect" and derive the relation between the ω and k-spectra. Third, we show that for shear driven flows the present model reproduces well the data at large strain rates while the widely used K - ∊ model does not.

scholarly journals Mathematical modeling of materially nonlinear problems in structural analyses, Part I: Theoretical fundamentals

2010 ◽  
Vol 8 (1) ◽  
pp. 67-78 ◽  
Author(s):  
Zoran Bonic ◽  
Verka Prolovic ◽  
Biljana Mladenovic
Keyword(s):  
Nonlinear Problems ◽  
Failure Surface ◽  
Plasticity Theory ◽  
Rigid Plastic ◽  
Material Models ◽  
Linear Elastic ◽  
Hardening Law ◽  
Plastic Yield ◽  
Normality Condition ◽  
Von Mises

Material models describe the way they behave when loaded. The paper presents the development of the model beginning with the simplest linear-elastic and rigid-plastic ones. The basic data in the plasticity theory have been defined, such as criterion and yield (failure) surface, hardening law, plastic yield law and normality condition. Yield criteria of Tresca, Von Mises, Mohr-Coulomb and Drucker-Prager were given separately.

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