Polycrystal Simulations Investigating the Effect of Additional Slip System Availability in a 6063 Aluminum Alloy at Elevated Temperature

2008 ◽  
Vol 130 (2) ◽  
Author(s):  
Antoinette M. Maniatty ◽  
David J. Littlewood ◽  
Jing Lu
Keyword(s):  
Aluminum Alloy ◽  
Elevated Temperature ◽  
Compression Test ◽  
Elevated Temperatures ◽  
Material Model ◽  
Grain Structure ◽  
Slip Systems ◽  
Modeling Framework ◽  
Element Analysis ◽  
6063 Aluminum Alloy

In order to better understand and predict the intragrain heterogeneous deformation in a 6063 aluminum alloy deformed at an elevated temperature, when additional slip systems beyond the usual octahedral slip systems are active, a modeling framework for analyzing representative polycrystals under these conditions is presented. A model polycrystal that has a similar microstructure to that observed in the material under consideration is modeled with a finite element analysis. A large number of elements per grain (more than 1000) are used to capture well the intragranular heterogeneous response. The polycrystal model is analyzed with three different sets of initial orientations. A compression test is used to calibrate the material model, and a macroscale simulation of the compression test is used to define the deformation history applied to the model polycrystal. In order to reduce boundary condition effects, periodic boundary conditions are applied to the model polycrystal. To investigate the effect of additional slip systems expected to be active at elevated temperatures, the results considering only the 12 {111}⟨110⟩ slip systems are compared to the results with the additional 12 {110}⟨110⟩ and {001}⟨110⟩ slip systems available (i.e., 24 available slip systems). The resulting predicted grain structure and texture are compared to the experimentally observed grain structure and texture in the 6063 aluminum alloy compression sample as well as to the available data in the literature, and the intragranular misorientations are studied.

Study on the Formability of Aluminium Alloy Sheets at Room and Elevated Temperatures

2016 ◽  
Vol 877 ◽  
pp. 393-399
Author(s):  
Jia Zhou ◽  
Jun Ping Zhang ◽  
Ming Tu Ma
Keyword(s):  
Mechanical Properties ◽  
Aluminum Alloy ◽  
Elevated Temperature ◽  
Aluminium Alloy ◽  
Aluminium Alloys ◽  
Elevated Temperatures ◽  
Hot Stamping ◽  
Natural Aging ◽  
Alloy Sheet ◽  
Aluminum Alloy Sheet

This paper presents the main achievements of a research project aimed at investigating the applicability of the hot stamping technology to non heat treatable aluminium alloys of the 5052 H32 and heat treatable aluminium alloys of the 6016 T4P after six months natural aging. The formability and mechanical properties of 5052 H32 and 6016 T4P aluminum alloy sheets after six months natural aging under different temperature conditions were studied, the processing characteristics and potential of the two aluminium alloy at room and elevated temperature were investigated. The results indicated that the 6016 aluminum alloy sheet exhibit better mechanical properties at room temperature. 5052 H32 aluminum alloy sheet shows better formability at elevated temperature, and it has higher potential to increase formability by raising the temperature.

Evaluation of Limit Load Analysis Methods Applied to High Temperature Design: Part 2 — Analysis and Results

2014 ◽  
Author(s):  
Dave Dewees ◽  
Rahul Jain
Keyword(s):  
High Temperature ◽  
Elevated Temperature ◽  
Failure Modes ◽  
Limit Load ◽  
Material Model ◽  
Creep Model ◽  
Element Analysis ◽  
Allowable Stresses ◽  
Inelastic Material ◽  
Load Analysis

Limit Load Analysis (LLA) is a powerful tool for design at temperatures below the creep range, and there is desire to extend the method to the elevated temperature (creep) regime. However, there is no direct relationship between LLA and elevated temperature allowable stresses and failure modes, such that the basic LLA methods or results must be manipulated in some way to be generally meaningful for elevated temperature design. The most direct way to judge simplified methods is against a rigorous solution; this requires an inelastic material model consistent with allowable stresses. Such a creep model was described in Part 1 of this work (the Omega model), and subsequently applied in a rational way to the problem of primary load carrying capacity and design using a simple sample problem. In this paper, extension is made to the case of a typical steam header, and existing simplified (LLA) methods are compared against further detailed transient inelastic finite element analysis. Recommendations are then made for the application of LLA to evolving ASME high temperature design rules. Paper published with permission.

Analysis and Compression Testing of 2024 and 8009 Aluminum Alloy Zee-Stiffened Panels

1994 ◽  
Vol 116 (2) ◽  
pp. 238-243 ◽  
Author(s):  
R. Friedman ◽  
J. Kennedy ◽  
D. Royster
Keyword(s):  
Aluminum Alloy ◽  
High Temperature ◽  
Compression Test ◽  
Elevated Temperatures ◽  
Alloy Sheet ◽  
Strength Analysis ◽  
Microstructural Stability ◽  
Stiffened Panels ◽  
Potential Weight ◽  
Spot Welded

Zee-stiffened compression test panels, fabricated with dispersion-strengthened, high-temperature 8009 aluminum alloy sheet, were evaluated to determine the alloy’s feasibility for compression-critical applications. A compression panel design configuration was obtained using a strength analysis program that predicts the post-skin buckling strength of flat or curved-skinned, metallic-stiffened structure. Three short-column panels were tested to failure at room temperature: (a) a baseline riveted panel fabricated with 2024-T62 aluminum zee stringers and a 2024-T81 aluminum skin, (b) a riveted panel fabricated with 8009 aluminum zee stringers and skin, and (c) a resistance spot-welded panel fabricated with 8009 aluminum zee stringers and skin. The 8009 alloy exhibited pronounced, compressive strength anisotropy, necessitating panel orientation to take advantage of the higher compressive yield in the sheet transverse direction. Compression test results were in good agreement with the predicted compression allowables since they were within 5 percent of the test strength. The 8009 aluminum riveted panel exhibited superior skin buckling resistance and failed in the wrinkling mode, as predicted, at a load approximately 15 percent higher than that of the baseline 2024 panel. The spotwelded 8009 panel did not fail in the wrinkling mode since the spot welds failed in tension shortly after the skin locally buckled. The latter test indicates that the spot welded skin-stringer combinations should not be used above the buckling stress. Due to its excellent microstructural stability at elevated temperatures, high-temperature compression panels of 8009 alloy offer potential weight savings of 25 percent compared with conventional aluminum alloys.

Development of Test Equipment for Measuring Compression Characteristics of Sheet Gaskets at Elevated Temperature

2007 ◽  
Author(s):  
Toshimichi Fukuoka ◽  
Masataka Nomura ◽  
Yoshihiko Hata ◽  
Takashi Nishikawa
Keyword(s):  
Elevated Temperature ◽  
Compression Test ◽  
Elevated Temperatures ◽  
Testing Procedure ◽  
Great Difficulty ◽  
Test Equipment ◽  
Experimental Point ◽  
Stress Strain ◽  
Sealing Performance ◽  
Compression Characteristics

Evaluation of the sealing performance of pipe flange connection is significantly important for the safety of pipe line structures. The compression characteristics of sheet gaskets primarily affect the mechanical behavior of flanged connections. It is known that the stiffness of sheet gaskets decreases with an increase in temperature. Therefore, the compression test must be conducted at various levels of elevated temperatures. From the experimental point of view, however, a great difficulty is involved in measuring the compression characteristics of gaskets at elevated temperature. For this reason, a definite testing procedure has not yet been established. In this paper, a prototype of compression test equipment has been developed for measuring the stress-strain curves of sheet gaskets at elevated temperature. The test equipment is compact and the experiments can be conducted with a fairly easy operation. It can control the gasket stress from zero to 30MPa while keeping the temperature of test specimen at different levels from room temperature to 300° C and higher. Aramid sheet gaskets are selected as test specimens. Experimental results show that the gasket stiffness drops with an increase in temperature. The shapes of the compression curves at different temperatures are similar, and those curves move in the direction of lower stiffness as the temperature is increased. It is concluded that the test equipment proposed here has a high promise to measure the stress-strain curves of sheet gaskets and estimate the sealing performance of pipe flange connections at elevated temperature.

Effect of Bi Addition on Thermal Stability and Tensile Ductility of Mg-3%Zn-0.4%Zr Alloy

2010 ◽  
Vol 654-656 ◽  
pp. 647-650
Author(s):  
Joong Hwan Jun ◽  
Min Ha Lee
Keyword(s):  
Thermal Stability ◽  
Tensile Strength ◽  
Elevated Temperature ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Tensile Ductility ◽  
Grain Structure ◽  
Hot Rolled ◽  
Thermal Stability Of ◽  
Zr Alloy

Thermal stability of  grains and tensile ductilities at room and elevated temperatures were investigated and compared for Mg-3%Zn-0.4%Zr and Mg-3%Zn-0.4%Zr-1%Bi alloys in hot-rolled state. The Bi-added alloy showed slightly finer-grained microstructure with enhanced thermal stability, which is closely associated with fine Mg-Bi compounds acting as obstacles for the migration of grain boundaries. The Mg-3%Zn-0.4%Zr-1%Bi alloy exhibited better tensile strength at room temperature and tensile ductilities at elevated temperature. Finer and more homogeneous grain structure with higher thermal stability would be responsible for the enhanced tensile properties in the Bi-added alloy.

scholarly journals Compressive strength of partially stiffened cylinders at elevated temperatures

2020 ◽  
Vol 19 (1) ◽  
pp. 131-142
Author(s):  
Egler Araque ◽  
Carlos Graciano ◽  
David G. Zapata-Medina ◽  
Octavio Andrés González-Estrada
Keyword(s):  
Compressive Strength ◽  
Elevated Temperature ◽  
Elevated Temperatures ◽  
Compressive Loading ◽  
Structural Response ◽  
Pressure Vessels ◽  
Element Analysis ◽  
Pressure Profiles ◽  
Complex Design ◽  
The Finite Element Analysis

This work presents the finite element analysis of partially stiffened cylinders subjected to axial compression at elevated temperatures. The compressive strength is calculated for self-weight conditions and the influence of the temperature on the material response is also investigated. In the oil industry, pressure vessels are commonly used operating at complex design conditions such as high-pressure profiles and/or elevated temperature gradients which affect considerably the structural response of inner components. Among them, risers become sensitive steel elements withstanding heavy compressive loading due to self-weight, as well as, insulation elements added toprotect them from the elevated temperature gradient. Most risers structurally fail at the bottom end due to buckling caused by self-weight and temperature effects. To remediate this situation and to guarantee the integrity of the riser, longitudinal stiffeners are welded at the bottom end. Hence, a proper determination of the compressive strength of the cylinder, taking into account the influence of the longitudinal stiffening and the corresponding temperature, is required.Results indicate that the use oflongitudinal stiffeners in deformed cylinders increases the strength to buckling in percentages that vary according to the cross-section of the profiles.

Formability Characteristics of AA5083 Sheets under Hot Forming Conditions

2013 ◽  
Vol 549 ◽  
pp. 356-363
Author(s):  
Stefania Bruschi ◽  
Andrea Ghiotti ◽  
Francesco Michieletto
Keyword(s):  
Aluminum Alloy ◽  
Elevated Temperature ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Superplastic Forming ◽  
Tensile Tests ◽  
Processing Route ◽  
Strain Rates ◽  
Fine Grained ◽  
Axial Tensile

The production of aluminum alloy components through sheet forming processes conducted at elevated temperatures is gaining more and more interest as it gives raise to the possibility of a significant enhancement of the metal formability characteristics, compared to room temperature forming. Aluminum alloy AA5083 blanks, which present a limited formability at room temperature, are usually formed through superplastic forming at elevated temperature: however, this processing route is too slow to be applicable for large batch production, typical for instance of the automotive industry. The paper is aimed at exploring the formability characteristics of the AA5083 when deformed at elevated temperature, but in a range of strain rates higher than those usually applicable in superplastic forming. To this aim, uni-axial tensile tests were carried out, in order to record the material formability characteristics as a function of temperature and strain rate, and to correlate them with the developed microstructural features. It is shown that it is possible to work at higher strain rates, still preserving a significant formability, even without using a conventional fine-grained superplastic alloy.

Evaluation of Limit Load Analysis Methods Applied to High Temperature Design: Part 1 — Consistent Material Modeling

2014 ◽  
Author(s):  
Dave Dewees ◽  
Rahul Jain
Keyword(s):  
Elevated Temperature ◽  
Failure Modes ◽  
Limit Load ◽  
Material Model ◽  
Element Analysis ◽  
Allowable Stresses ◽  
Safety Margins ◽  
Advanced Analysis ◽  
Load Analysis ◽  
Pressure Part

Design-by-Rule codes (i.e. ASME Section I, EN 12952) already exist for elevated temperature (creep) design and have been successfully used for decades; however, there is motivation to optimize designs, or to assess non-standard ones. Limit Load Analysis (LLA) is the simplest advanced analysis method, and a powerful and widely-used tool for establishing compliance with required pressure part safety margins for operation at temperatures below the creep range. However, there is no direct relationship between LLA and elevated temperature allowable stresses and failure modes, such that the basic LLA methods or results must be manipulated in some way to be generally meaningful. With this in mind, review of proposed elevated temperature LLA methods (which are discussed in Part 2 of this work) by comparison to detailed transient inelastic finite element analysis allows for rigorous assessment of simplifications. Specification of an elevated temperature material model that is consistent with traditional allowable stresses for the detailed analysis is described in this paper (Part 1), and the material model and simplified methods are applied to the case of a typical steam header in the next (Part 2). Paper published with permission.

Lifetime Prediction of Tires with Regard to Oxidative Aging5

2008 ◽  
Vol 36 (1) ◽  
pp. 63-79 ◽  
Author(s):  
L. Nasdala ◽  
Y. Wei ◽  
H. Rothert ◽  
M. Kaliske
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Temperature Distribution ◽  
Superposition Principle ◽  
Accelerated Aging ◽  
Material Model ◽  
Aging Behavior ◽  
Element Analysis ◽  
Material Parameters ◽  
Reaction Processes

Abstract It is a challenging task in the design of automobile tires to predict lifetime and performance on the basis of numerical simulations. Several factors have to be taken into account to correctly estimate the aging behavior. This paper focuses on oxygen reaction processes which, apart from mechanical and thermal aspects, effect the tire durability. The material parameters needed to describe the temperature-dependent oxygen diffusion and reaction processes are derived by means of the time–temperature–superposition principle from modulus profiling tests. These experiments are designed to examine the diffusion-limited oxidation (DLO) effect which occurs when accelerated aging tests are performed. For the cord-reinforced rubber composites, homogenization techniques are adopted to obtain effective material parameters (diffusivities and reaction constants). The selection and arrangement of rubber components influence the temperature distribution and the oxygen penetration depth which impact tire durability. The goal of this paper is to establish a finite element analysis based criterion to predict lifetime with respect to oxidative aging. The finite element analysis is carried out in three stages. First the heat generation rate distribution is calculated using a viscoelastic material model. Then the temperature distribution can be determined. In the third step we evaluate the oxygen distribution or rather the oxygen consumption rate, which is a measure for the tire lifetime. Thus, the aging behavior of different kinds of tires can be compared. Numerical examples show how diffusivities, reaction coefficients, and temperature influence the durability of different tire parts. It is found that due to the DLO effect, some interior parts may age slower even if the temperature is increased.

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