Propagation Properties of an Off-Axis Hollow Gaussian-Schell Model Vortex Beam in Anisotropic Oceanic Turbulence

Based on the extended Huygens–Fresnel principle and the power spectrum of anisotropic oceanic turbulence, the analytical expressions of the average intensity and coherence properties of an off-axis hollow Gaussian-Schell model (OAHGSM) vortex beam propagating through anisotropic oceanic turbulence were derived. The effects of turbulent ocean and beam characteristic parameters on the evolution properties of the OAHGSM vortex beam were analyzed in detail. Our numerical simulation results showed that the OAHGSM vortex beam with a larger position factor is more focusable. Meanwhile, the OAHGSM vortex beam eventually evolves into a Gaussian-like beam after propagating through the anisotropic oceanic turbulent channel. The speed of this process can be accelerated by the decrease of the hollow order, topological charge, beam width, and transverse coherence width of the beam. The results also indicated that the normalized average intensity spreads more greatly and the spectral degree of coherence decays more rapidly for the smaller dissipation rate of the kinetic energy per unit mass of fluid, the smaller anisotropic coefficient, the smaller inner scale factor, the larger dissipation rate of the mean-squared temperature, and the higher temperature–salinity contribution ratio.

Applications of the Hill 1948 Yield Criterion Development, Performance Evaluation and Comparison for Describing the Behaviour of Different CRCA Grades

The sheet metal forming processes in several industries like automobile and aerospace suppose the yielding of the sheet metals once strained. Yielding is categorized by the plastic flow of the materials once strained. The yield purpose just in case of uniaxial tension may be simply determined from the stress strain graph, however just in case of multi axial stresses it gets complicated. A relationship among the principal stresses is required requiring the circumstances underneath that plastic flow happens. This complexity is addressed by the anisotropic yield functions. Also, the investigation to get yield loci could also be expensive and time taking. In such case these yield functions prove to be very effective. The yield criteria also facilitate in decisive planar distribution of yield stresses and anisotropic coefficients which gives a decent estimate of these mechanical parameters while not having to through the pain of experimental determination. This study aims at using Hill 1948 criterion to get the Yield Surface Diagrams for three different grades of CRCA Sheets such as ordinary (o), Deep Drawing (DD) and Extra Deep Drawing (EDD) to get the planar distribution of the uniaxial yield stress and anisotropic coefficient. Also, the performance analysis of different grades the distributions are done using accuracy index.

Experimental Study and Modelling of the Ferritic Steel Anisotropic Behavior under Associated and Non-Associated Flow Rule

In the present study, two different yield criteria were investigated to model and compare the yield thresholds functions for the plastic behavior of rolled sheets. These two different yield criteria as described via Hill48 yield quadratic and F. Barlat Yld2000-2d non-quadratic criterion. For this purpose, an experimental device of simple tensile test and the studied material are described. The experimental results in terms of Yield stress and Anisotropic coefficient are estimated from the Associated Flow Rule (AFR) and Non-Associated Flow Rule (NAFR). However, it is found that the criterion of Yld2000-2d is the most appropriate model in comparison with the experimental results.

Performance Evaluation of Yield Function and Comparison of Yielding Characteristics of SS 304 in Annealed and Unannealed Conditions

Sheet metal forming forms in numerous industries like vehicle depend on the yielding of the sheet metals when strained. Yielding is portrayed by plastic flow of the materials when strained. The yield point if there should be an occurrence of uniaxial tension can be effectively decided from the pressure strain diagram, yet if there should arise an occurrence of multi axial Stresses it gets complicated. A connection between the principal stresses is required determining the conditions under which plastic flow occurs. This intricacy is tended to by the anisotropic yield capacities. Likewise, the tests used to acquire yield loci might be costly and time taking in such case these yield capacities end up being exceptionally viable. The yield criteria additionally help in deciding planar distribution of yield stresses and anisotropic coefficients, which gives a decent gauge of these mechanical parameters without having to through the pain of trial assurance. This project aims at using Hill 1948 criterion to obtain the Yield surface Diagrams for SS304 in annealed and original state and subsequently obtain the planar distribution of the uniaxial yield stress and anisotropic coefficient. Also, the performance evaluation of both the distributions will be done using accuracy index.

Propriedades físico-mecânicas da madeira de Chrysophyllum marginatum

Esse estudo objetivou avaliar as propriedades físico-mecânicas da madeira de Chrysophyllum marginatum (Hook. e Arn.) Radlk. Foram utilizadas três árvores com 20,3 ± 6 cm de diâmetro. Por regressão, determinou-se a variação no sentido base-topo de retratibilidade, coeficiente anisotrópico, teor de umidade saturado e massa específica básica. Para caracterizar a flexão estática na primeira tora, nas condições úmida e seca ao ar, foi realizada análise de variância pelo teste de Tukey. Observou-se decréscimo das contrações radial e tangencial e da massa específica básica da madeira no sentido base-topo, inversamente ao teor de umidade saturado, que apresentou uma variação crescente. Na análise do coeficiente anisotrópico, verificou-se uma tendência de acréscimo até 1,30 m de altura, seguido de estabilização a partir dessa posição até o topo. A contração longitudinal apresentou tendência de decréscimo até, aproximadamente, 40% de altura, seguido de acréscimo até a altura de inserção do primeiro galho vivo. As médias do coeficiente anisotrópico e da massa específica básica foram 2,3 kg m-3 e 594 kg m-3, respectivamente. A condição de umidade seca ao ar apresentou maior resistência à flexão estática do que quando saturada e os valores dos módulos de elasticidade e de ruptura foram semelhantes aos encontrados em estudos de Eucalyptus saligna e Carya illinoinensis.Physical and mechanical properties of Chrysophyllum marginatum woodThis study aimed to evaluate the physical and mechanical properties of the wood of Chrysophyllum marginatum (Hook. And Arn.) Radlk. We used three trees with 20.3 ± 6 cm of diameter. It was determined by regression analysis the variation bottom-up of shrinkage, anisotropic coefficient, saturate moisture content and basic density. To characterize the static bending in the first log, in saturate and air dried conditions, it was performed variance analysis using Tukey›s test. It was observed a decrease in radial and tangential contractions and basic density on bottom-up direction. Saturate moisture content increased, considering the same direction. Anisotropic coefficient presented increase tendency up to 1.30 m height followed by stabilization from that position to the top. It was observed decreasing tendency of longitudinal contraction to approximately 40% of total height, followed by increasing up to the insertion of the first living branch. Mean anisotropic coefficient and basic density were 2.3kg m-³ and 594 kg m-³, respectively. Air dry condition showed greater static bending resistance than when saturate. Values of rupture and elasticity modulus were similar to those found in studies with Eucalyptus saligna and Carya illinoinensis.Index terms: Shrinkage; Anisotropic coefficient; Static bending

EFFECT OF ASYMMETRIC ROLLING ON FORMABILITY OF PURE ALUMINIUM

Uniaxial tensile test was carried out at different loading direction (0o, 90o and 45o) on rolled aluminiumsheets. The anisotropic coefficient was analyzed to reveal formability characteristics. The shear strain that wasimposed during the ASR was extensive and the shear marks was inclined more or less linearly without beingzigzag or spiral lines. The ASRC improved the normal anisotropy coefficient compared to CR specimens. Thehighest normal anisotropy and the lowest planar anisotropy were observed by ASRC samples. Therefore, it wasfound that, asymmetric rolling especially ASRC can be used to improve the formability of aluminium thick sheets.

The Research of Center Shaft Bracket Stamping Simulation Technology Based on Dynaform

Aiming at the center shaft bracket sheet extension parts, its stamping calculation is simulated based on the sheet metal forming with nonlinear finite element software Dynaform. The contours varying with blank holder forces, friction coefficients and material performance parameters (sheet hardening exponent n and thick anisotropic coefficient r) are obtained by using the simulation software. The impact of the factors on the central shaft bracket parts stamping is analysised by using the contours, provide the theory to eliminate the fold and fracture in the stamping process.

HALL EFFECT, MAGNETORESISTIVITY AND MAGNETIC PROPERTIES OF MgB2 THIN FILMS WITH AlN BUFFER LAYERS

MgB 2 thin films were deposited at low temperature substrates, in situ, on c-plane sapphire substrates, with the aluminium nitride (AlN) buffer layers, using the multiple-target sputtering system. The magnetoresistivities were measured using dc-five probe method in applied magnetic field up to 9 Tesla. The upper critical field anisotropy, HC2(T) and irreversibility field H irr (T) versus temperature were determined. The Hall coefficients RH are slightly temperature dependent and positive in the normal state. The critical temperature of 30–32 K and critical current density of 106-107 A/cm 2 at 4.2 K were obtained. Using extracted data, the coherence length ξo, anisotropic coefficient γ and penetration depth λL were calculated.

MAGNETORESISTIVITY AND MAGNETIC PROPERTIES IN MgB2 THIN FILMS

Magnetotransport data on MgB 2 thin films, fabricated on Al 2 O 3 substrates using electron–bean deposition and Mg diffusion method are reported for applied magnetic fields up to 9 T. The upper critical field anisotropy, lower critical field and irreversibility field versus temperature are determined. The Hall coefficient is slightly temperature-dependent and positive in the normal state. Using the extracted data, the electronic mean free path, coherence length ξ0, anisotropic coefficient γ and penetration depth λ are calculated.

Yield Surfaces of SUS304 Under Cyclic Loading

To formulate the constitutive equations for cyclic plasticity, the subsequent yield surfaces should be examined carefully. In this paper, the subsequent yield surfaces have been examined from the experiment for the initially isotropic material of SUS304 subject to cyclic loading, using a 50µm/m offset strain criterion for yielding probed at the current center of the yield surface. The experiment shows a translation, distorsion, and rotation of the subsequent yield surfaces because of the deformation-induced-anisotropy due to proportional or nonproportional cyclic loading in tension-torsion space. These yield surfaces could be represented by the quadratic function of stresses with fourth rank anisotropic coefficient tensor components. These anisotropic coefficient tensor components are found to be represented by the strain amplitude of cyclic loading. As a result, the loading function obtained shows availability to derive the constitutive equations of cyclic plasticity.