Cavity Nucleation in AL 5083 Alloys

1999 ◽  
Vol 601 ◽  
Author(s):  
N. Chandra ◽  
Z. Chen
Keyword(s):  
Electron Microscopy ◽  
Rolling Direction ◽  
Interfacial Strength ◽  
Superplastic Forming ◽  
Simplified Model ◽  
Hard Phase ◽  
Cavity Nucleation ◽  
Material Parameters ◽  
State Of Stress ◽  
Process Material

AbstractIn this paper we address the controversial issue of nucleation of cavities in Al 5083 alloys. We focus on the origin of cavities during the manufacture of these alloys into SPF (superplastic forming) sheet form. Experimental observations on the pre-existing cavities in this alloy are made using optical and electron microscopy. The effects of rolling direction and state of stress during superplastic deformations on the formation of cavities are also discussed. Numerical simulations of the sheet manufacturing process are carried out to understand the effect of hard phase/matrix, mechanical properties and interfacial strength on the origin of cavities. Based on the numerical results, a simplified model relating the process, material parameters and the cavity nucleation is presented.

Effect of State of Stress on the Cavitation Behavior of Al 5083 Superplastic Material

2005 ◽  
Vol 475-479 ◽  
pp. 2931-2936 ◽  
Author(s):  
Names Chandra ◽  
Marwan K. Khraisheh ◽  
Peter N. Kalu
Keyword(s):  
Rolling Direction ◽  
Superplastic Forming ◽  
Complex Stress ◽  
The State ◽  
Sheet Rolling ◽  
State Of Stress ◽  
Mapping Process ◽  
Stress States ◽  
Cavitation Behavior ◽  
The Right

In this paper we address the controversial issue of nucleation of cavities in Al 5083 alloys and their subsequent growth to coalescence and failure. We focus on the origin and growth of cavities not only during the primary processing of Al 5083 in sheet forms, but also during the manufacture of these sheets into SPF (superplastic forming) components. Experimental observations of pre-existing cavities in this alloy are made using optical and electron microscopy. The role of sheet rolling direction, and the state of stress during superplastic deformation on the cavity formation and coalescence are also discussed. The effect of the state of stress (uniaxial, plane strain, balanced biaxial, and tri-axial) on the growth characteristics of cavitation is also examined. It is found that the uniaxial model based cavitation cannot directly be extended to predict the behavior of more complex stress states, unless great care is taken to identify the right strain measure for the mapping process.

Effects of Homogenization-Free on the Microstructures of an Al-Mg-Si-Cu Hot-Rolled Plate for Automotive Pannel

2018 ◽  
Vol 941 ◽  
pp. 1529-1534
Author(s):  
Ni Tian ◽  
Qi Long Liu ◽  
Zi Yan Zhao ◽  
Gang Zhao ◽  
Kun Liu
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Aluminum Alloy ◽  
Rolling Direction ◽  
Rolled Plate ◽  
Alloy Plate ◽  
Solution Treated ◽  
Aluminum Alloy Plate ◽  
Hot Rolled ◽  
Scanning Electron

The microstructure of Al-1.01Mg-1.11Si-0.38Cu-0.69Mn aluminum alloy plate hot-rolled from homogenization and homogenization-free ingots were investigated by optical microscopy and scanning electron microscopy assisted with energy dispersive spectroscopy (SEM/EDS). The results showed that there are 3 main kinds of constituents such as Mg2Si, AlCuMgSi and AlFeMnSi in the as-cast Al-1.01Mg-1.11Si-0.38Cu-0.69Mn aluminum alloy ingot. After homogenization treated at 545°C for 24h, the black Mg2Si and the white bright AlCuMgSi particles in the ingot dissolved into matrix, but the grey AlFeMnSi phase partly dissolved, contracted into sphere and become coarse, many ultrafine dispersoids appear in the dendritic arms. The constituents in the plates hot-rolled from the homogenization and homogenization-free ingots are both distributed as broken chains along the rolling direction. However, compared with the particles configuration in the plate that hot-rolled from homogenization ingot, the particles in the plate that hot-rolled from the homogenization-free ingot are finer, more numerous and more homogenous, and with insufficient recrystallization when the plates are solution treated at 545°C for 2 h and then water quenched.

Wave Propagation in Viscoelastic Laminates

1971 ◽  
Vol 38 (2) ◽  
pp. 448-454 ◽  
Author(s):  
M. Stern ◽  
A. Bedford ◽  
C. H. Yew
Keyword(s):  
Wave Propagation ◽  
Effective Modulus ◽  
Simplified Model ◽  
Structure Parameter ◽  
Longitudinal Waves ◽  
Material Parameters ◽  
Dispersion And Attenuation ◽  
Attenuation Characteristics ◽  
Representative Material ◽  
Effect Of Structure

For a simplified model of a laminated medium consisting of alternating layers of elastic and viscoelastic materials, the dispersion and attenuation characteristics for “plane,” longitudinal waves propagating in the direction of the layering are obtained. The dispersion and attenuation curves depend on a structure parameter involving the thickness of the layers and can deviate significantly from corresponding results for a continuum “effective-modulus” model. Curves are presented for a specific case with representative material parameters showing the effect of structure and of variations in the parameters of the composite.

Theoretical Analysis on the Ultimate Bearing Capacity for Steel Tubular Transmission Tower’s Joints with Annular Plate

2014 ◽  
Vol 664 ◽  
pp. 175-181 ◽  
Author(s):  
Zhi Juan Rong ◽  
Xue Ming Wang ◽  
Bao Hua Lv ◽  
Xin Yue Zhang ◽  
Ling Zhang
Keyword(s):  
Theoretical Analysis ◽  
Bearing Capacity ◽  
Annular Plate ◽  
Ultimate Bearing Capacity ◽  
Simplified Model ◽  
Force Distribution ◽  
Element Analysis ◽  
Energy Principle ◽  
State Of Stress ◽  
Principle Theory

The aim of this paper is to study the ultimate bearing capacity of steel tubular transmission tower’s joint with annular plate based on the theoretical analysis. A simplified model of annular plate joints was performed to investigate the force distribution of the tube-gusset joints. To obtain the state of stress and ultimate bearing capacity, the annular plate with clamped boundary condition on the inner edges and subjected to diametric loading is employed in this study by the direct integration and thin plate energy principle theory. Experiment and finite element analysis are carried out and the results show that both are the similar.

Incipient Slip Conditions in the Rolling Contact of Tyred Wheels

2010 ◽  
Vol 224 (10) ◽  
pp. 2049-2054 ◽  
Author(s):  
S Reina ◽  
D A Hills ◽  
D Dini
Keyword(s):  
Contact Problem ◽  
Closed Form ◽  
Rolling Contact ◽  
Simplified Model ◽  
Practical Case ◽  
Closed Form Solutions ◽  
Steel Wheel ◽  
State Of Stress ◽  
Wide Range ◽  
Tractive Rolling

The contact problem of a driving tyred wheel, pressed and rolling over an elastically similar half-plane, is considered. Although applicable to a wide range of shrink-fitted assemblies, the simplified model is solved to study the practical case of an elastically similar steel tyre mounted on a locomotive steel wheel subjected to tractive rolling. The behaviour of the system at the tyre—substrate interface is studied using closed-form solutions to calculate the state of stress within the tyre. Conditions leading to incipient slip and/or plasticity are identified and mapped for different loads and geometries.

Sheet Orientation Effects on the Hot Formability Limits of Lightweight Alloys

2011 ◽  
Vol 133 (6) ◽  
Author(s):  
Fadi Abu-Farha ◽  
Louis G. Hector
Keyword(s):  
Rolling Direction ◽  
Superplastic Forming ◽  
Strain Ratio ◽  
Forming Limit ◽  
Specific Strain ◽  
Plastic Forming ◽  
Lightweight Alloys ◽  
Quick Plastic Forming ◽  
The Relationship ◽  
5083 Aluminum Alloy

The formability curves of AZ31B magnesium and 5083 aluminum alloy sheets were constructed using the pneumatic stretching test at two different sets of forming conditions. The test best resembles the conditions encountered in actual hydro/pneumatic forming operations, such as the superplastic forming (SPF) and quick plastic forming (QPF) techniques. Sheet samples were deformed at (400 °C and 1 × 10−3 s−1) and (450 °C and 5 × 10−3 s−1), by free pneumatic bulging into a set of progressive elliptical die inserts. The material in each of the formed domes was forced to undergo biaxial stretching at a specific strain ratio, which is simply controlled by the geometry (aspect ratio) of the selected die insert. Material deformation was quantified using circle grid analysis (CGA), and the recorded planar strains were used to construct the forming limit curves of the two alloys. The aforementioned was carried out with the sheet oriented either along or across the direction of major strains in order to establish the relationship between the material’s rolling direction and the corresponding limiting strains. Great disparities in limiting strains were found in the two orientations for both alloys; hence, a “composite FLD” is introduced as an improved means for characterizing material formability limits.

scholarly journals Material Identification Using a Bi-Axial Test Machine

2006 ◽  
Vol 3-4 ◽  
pp. 91-98 ◽  
Author(s):  
Paulo Flores ◽  
Pierre Moureaux ◽  
Anne Marie Habraken
Keyword(s):  
Plane Strain ◽  
Simple Shear ◽  
Rolling Direction ◽  
Mechanical Tests ◽  
Test Machine ◽  
Shear Tests ◽  
Sheet Rolling ◽  
Material Parameters ◽  
Optical Strain ◽  
Material Parameters Identification

This paper shows the identification of material parameters for a DC06 IF steel sheet of 0.8 mm by mechanical tests. The experimental equipment used consists of a tensile test machine, a bi-axial test machine able to perform plane-strain and simple shear tests separately or simultaneously and an optical strain gauge. Tensile, plane-strain and simple shear tests were performed at 0°, 45° and 90° from the sheet rolling direction in order to identify Hill 1948 and Hosford 1979 yield criteria. Two identification methods are used: one based on strain measurements (anistropy coefficients) and the other one based on stress measurements (plastic contours). The results confirm that mechanical tests applying other stress-states than tensile are required to obtain accurate material parameters identification.

scholarly journals Determination of Material Parameters during Superplastic Forming of AA 5086 Alloy

2014 ◽  
Vol 97 ◽  
pp. 1379-1386 ◽  
Author(s):  
S. Ramesh Babu ◽  
S. Deivanayagam ◽  
M. Aravind
Keyword(s):  
Superplastic Forming ◽  
Material Parameters

scholarly journals A Comparative Study of Three Different Chemical Vapor Deposition Techniques of Carbon Nanotube Growth on Diamond Films

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Betty T. Quinton ◽  
Paul N. Barnes ◽  
Chakrapani V. Varanasi ◽  
Jack Burke ◽  
Bang-Hung Tsao ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Heat Sink ◽  
Microwave Plasma ◽  
Interfacial Strength ◽  
Chemical Vapor ◽  
Thermal Cvd ◽  
Carbon Nanotube Growth

This paper compares between the methods of growing carbon nanotubes (CNTs) on diamond substrates and evaluates the quality of the CNTs and the interfacial strength. One potential application for these materials is a heat sink/spreader for high-power electronic devices. The CNTs and diamond substrates have a significantly higher specific thermal conductivity than traditional heat sink/spreader materials making them good replacement candidates. Only limited research has been performed on these CNT/diamond structures and their suitability of different growth methods. This study investigates three potential chemical vapor deposition (CVD) techniques for growing CNTs on diamond: thermal CVD (T-CVD), microwave plasma-enhanced CVD (MPE-CVD), and floating catalyst thermal CVD (FCT-CVD). Scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (TEM) were used to analyze the morphology and topology of the CNTs. Raman spectroscopy was used to assess the quality of the CNTs by determining theID/IGpeak intensity ratios. Additionally, the CNT/diamond samples were sonicated for qualitative comparisons of the durability of the CNT forests. T-CVD provided the largest diameter tubes, with catalysts residing mainly at the CNT/diamond interface. The MPE-CVD process yielded non uniform defective CNTs, and FCT-CVD resulted in the smallest diameter CNTs with catalyst particles imbedded throughout the length of the nanotubes.

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