In this study, the dynamic deformation behavior of AA2219 aluminum alloy was investigated in two different temper conditions: T4 and T6, with a view to determining the effect of heat treatment on the microstructure and flow behavior of the material under high strain rates. Split Hopkinson pressure bar experiment was used in determining the dynamic response of the alloy while a digital image correlation system was employed in visualizing and tracking the surface deformation of the specimens. Optical microscopy and scanning electron microscopy were used to assess the microstructure of the material after following standard metallographic specimen preparation techniques. The results obtained showed heterogeneous deformation of the alloy in the two temper conditions. It was observed that the dynamic mechanical behavior of each sample preparation was dependent on its strength properties due to aging type, which in turn controls the metamorphosis of the strengthening precipitates and the initial microstructure. At the maximum strain rate of 3500 s-1, transformed bands leading to crack nucleation was observed in the AA2219-T4 aluminum alloy while AA2219-T6 had fractured at the same strain rate. The modes of crack formation and growth in the two alloys were found to be similar: nucleation, growth and coalescence of voids. However, shear band bifurcation phenomenon was observed only in the AA2219-T6 alloy.
Simulation Mechanical 2007 Crack 64 Bit Torrent Torrent
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During the last years high-resolution numerical weather prediction simulations have been used to examine meteorological events with increased convective activity. Traditional verification methods do not provide the desired level of information to evaluate those high-resolution simulations. To assess those limitations new spatial verification methods have been proposed. In the present study an attempt is made to estimate the ability of the WRF model (WRF -ARW ver3.5.1) to reproduce selected days with high convective activity during the year 2010 using those feature-based verification methods. Three model domains, covering Europe, the Mediterranean Sea and northern Africa (d01), the wider area of Greece (d02) and central Greece - Thessaly region (d03) are used at horizontal grid-spacings of 15km, 5km and 1km respectively. By alternating microphysics (Ferrier, WSM6, Goddard), boundary layer (YSU, MYJ) and cumulus convection (Kain--Fritsch, BMJ) schemes, a set of twelve model setups is obtained. The results of those simulations are evaluated against data obtained using a C-Band (5cm) radar located at the centre of the innermost domain. Spatial characteristics are well captured but with a variable time lag between simulation results and radar data. Acknowledgements: This research is cofinanced by the European Union (European Regional Development Fund) and Greek national funds, through the action "COOPERATION 2011: Partnerships of Production and Research Institutions in Focused Research and Technology Sectors" (contract number 11SYN_8_1088 - DAPHNE) in the framework of the operational programme "Competitiveness and Entrepreneurship" and Regions in Transition (OPC II, NSRF 2007--2013).
In this work, mechanical properties and fracture toughness of as-received and solution-treated aluminum alloy 5754 (AA 5754) are experimentally evaluated. Solution heat treatment of the alloy is performed at 530 C for 2 h, and then, quenching is done in water. Yield strength, ultimate tensile strength, impact toughness, hardness, fatigue life, brittle fracture toughness (K_Ic ) and ductile fracture toughness (J_Ic ) are evaluated for as-received and solution-treated alloy. Extended finite element method has been used for the simulation of tensile and fracture behavior of material. Heaviside function and asymptotic crack tip enrichment functions are used for modelling of the crack in the geometry. Ramberg-Osgood material model coupled with fracture energy is used to simulate the crack propagation. Fracture surfaces obtained from various mechanical tests are characterized by scanning electron microscopy.
High strength aluminum alloys are known as hard to weld alloys due to their high hot crack susceptibility. However, they have high potential for applications in light weight constructions of automotive industry and therefore it is needed to increase weldability. One major issue is the high hot cracking susceptibility. Vaporization during laser beam welding leads to a change of concentration of the volatile elements magnesium and zinc. Hence, solidification range of the weld and therefore hot cracking susceptibility changes. Additionally, different welding velocities lead to changed solidification conditions with certain influence on hot cracking. This paper discusses the influence of energy per unit length during laser beam welding of AA 7075 on the change of element concentration in the weld seam and the resulting influence on hot cracking susceptibility. Therefore EDS-measurements of weld seams generated with different velocities are performed to determine the change of element concentration. These quantitative data is used to numerically calculate the solidification range in order to evaluate its influence on the hot cracking susceptibility. Besides that, relative hot crack length and mechanical properties are measured. The results increase knowledge about welding of high strength aluminum alloy AA 7075 and hence support further developing of the welding process.
Ajayamohan, R. S. ; Goswami, Bhupendra Nath (2007)Dependence of simulation of boreal summer tropical intraseasonal oscillations on the simulation of seasonal mean Journal of the Atmospheric Sciences, 64 (2). pp. 460-478. ISSN 0022-4928
Bhargava, Lokegowda B. ; Devane, Russell ; Klein, Michael L. ; Balasubramanian, Sundaram (2007)Nanoscale organization in room temperature ionic liquids: a coarse grained molecular dynamics simulation study Soft Matter, 3 (11). pp. 1395-1400. ISSN 1744-683X
Bhatnagar, Shalabh (2007)Adaptive Newton-based multivariate smoothed functional algorithms for simulation optimization ACM Transactions on Modeling and Computer Simulation, 18 (1). pp. 1-35. ISSN 1049-3301
Bhowmick, R. ; Bysakh, S. ; Kawamura, Y. ; Yamasaki, M. ; Ramamurty, U. ; Chattopadhyay, K. (2007)Microstructure and mechanical properties of electron beam weld joints of a Zr41Ti14Cu12Ni10Be23 bulk metallic glass with Zr Journal of Materials Research, 22 (2). pp. 437-444. ISSN 0884-2914
Binder, K. ; Das, S. K. ; Horbach, J. ; Puri, S. (2007)Molecular dynamics simulations of surface-controlled phase separation of binary fluid mixtures confined in slit pores-online only The European Physical Journal - Special Topics, 141 . s1-s6. ISSN 1951-6355
Chandrachud, Prachi ; Josh, Kavita ; Kanhere, D. G. (2007)Thermodynamics of carbon-doped Al and Ga clusters: ab initio molecular dynamics simulations Physical Review B, 76 (23). 235423_1- 235423 _8. ISSN 0163-1829
Dev, Selvi ; Archibald Stuart, A. ; Ravi Dev Kumar, R. C. ; Murty, B. S. ; Prasad Rao, K. (2007)Effect of scandium additions on microstructure and mechanical properties of Al-Zn-Mg alloy welds Materials Science and Engineering A, 467 (1-2). pp. 132-138. ISSN 0921-5093
Dharmadhikari, J. A. ; Dharmadhikari, A. K. ; Makhija, V. S. ; Mathur, D. (2007)Multiple optical traps with a single laser beam using a simple and inexpensive mechanical element Current Science, 93 (9). pp. 1265-1270. ISSN 0011-3891
Dhotre, M. T. ; Joshi, J. B. (2007)Design of a gas distributor: three-dimensional CFD simulation of a coupled system consisting of a gas chamber and a bubble column Chemical Engineering Journal, 125 (3). pp. 149-163. ISSN 1385-8947
Dhotre, Mahesh T. ; Ekambara, Kalekudithi ; Joshi, Jyeshtharaj B. (2007)CFD simulation of the flow pattern for drag reducing fluids in turbulent pipe flows Journal of Chemical Engineering of Japan, 40 (4). pp. 304-311. ISSN 0021-9592
Fernandez, Moises ; Kärger, Jörg ; Freude, Dieter ; Pampel, André ; van Baten, J. M. ; Krishna, R. (2007)Mixture diffusion in zeolites studied by MAS PFG NMR and molecular simulation Microporous and Mesoporous Materials, 105 (1-2). pp. 124-131. ISSN 1387-1811
Gadagkar, Vikram ; Saha, Surajit ; Muthu, D. V. S. ; Maiti, Prabal K. ; Lansac, Yves ; Jagota, A. ; Moravsky, Alexander ; Loutfy, R. O. ; Sood, A. K. (2007)Double-walled carbon nanotubes under hydrostatic pressure: Raman experiments and simulations Journal of Nanoscience and Nanotechnology, 7 (6). pp. 1753-1759. ISSN 1533-4880
Ganguly, Suvankar ; Chakraborty, Suman (2007)A generalized enthalpy-based macro model for ternary alloy solidification simulations Numerical Heat Transfer, Part B: Fundamentals, 51 (3). pp. 293-313. ISSN 1040-7790 2ff7e9595c
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