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1
KRAUS, L. "LOCAL MAGNETIC ANISOTROPY AND MAGNETOANELASTIC EFFECT IN AMORPHOUS AND NANOCRYSTALLINE ALLOYS." International Journal of Modern Physics B 07, no. 01n03 (January 1993): 916–21. http://dx.doi.org/10.1142/s0217979293001979.
Анотація:
Anelastic deformation of amorphous and nanocrystalline metals results in an anisotropic distribution of atomic pair bonds. This mechanism can lead to rather strong macroscopic magnetic anisotropy in some alloys. Experimental results show that the creep-induced magnetic anisotropy of amorphous and nanocrystalline Fe- and Co-based alloys essentially depends both on TM and metalloid elements. This is a clear evidence that the random local magnetic anisotropy in these materials is closely related to the details of electronic structure. Based on this conclusion a model of bond -orientational anisotropy taking into account the distribution of local anisotropies in TM-based alloys is proposed.
2
Yu, Jing, Yongmei Zhang, Yuhong Zhao, and Yue Ma. "Anisotropies in Elasticity, Sound Velocity, and Minimum Thermal Conductivity of Low Borides VxBy Compounds." Metals 11, no. 4 (April 1, 2021): 577. http://dx.doi.org/10.3390/met11040577.
Анотація:
Anisotropies in the elasticity, sound velocity, and minimum thermal conductivity of low borides VB, V5B6, V3B4, and V2B3 are discussed using the first-principles calculations. The various elastic anisotropic indexes (AU, Acomp, and Ashear), three-dimensional (3D) surface contours, and their planar projections among different crystallographic planes of bulk modulus, shear modulus, and Young’s modulus are used to characterize elastic anisotropy. The bulk, shear, and Young’s moduli all show relatively strong degrees of anisotropy. With increased B content, the degree of anisotropy of the bulk modulus increases while those of the shear modulus and Young’s modulus decrease. The anisotropies of the sound velocity in the different planes show obvious differences. Meanwhile, the minimum thermal conductivity shows little dependence on crystallographic direction.
3
Sharma, M. D. "Rayleigh wave at the surface of a general anisotropic poroelastic medium: derivation of real secular equation." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 474, no. 2211 (March 2018): 20170589. http://dx.doi.org/10.1098/rspa.2017.0589.
Анотація:
A secular equation governs the propagation of Rayleigh wave at the surface of an anisotropic poroelastic medium. In the case of anisotropy with symmetry, this equation is obtained as a real irrational equation. But, in the absence of anisotropic symmetries, this secular equation is obtained as a complex irrational equation. True surface waves in non-dissipative materials decay only with depth. That means, propagation of Rayleigh wave in anisotropic poroelastic solid should be represented by a real phase velocity. In this study, the determinantal system leading to the complex secular equation is manipulated to obtain a transformed equation. Even for arbitrary (triclinic) anisotropy, this transformed equation remains real for the propagation of true surface waves. Such a real secular equation is obtained with the option of boundary pores being opened or sealed. A numerical example is solved to study the existence and propagation of Rayleigh waves in porous media for the top three (i.e. triclinic, monoclinic and orthorhombic) anisotropies.
4
Garemstani, Hamid, Dong Sheng Li, and Moe A. Khaleel. "Microstructure Sensitive Design and Quantitative Prediction of Effective Conductivity in Fuel Cell Design." Materials Science Forum 561-565 (October 2007): 315–18. http://dx.doi.org/10.4028/www.scientific.net/msf.561-565.315.
Анотація:
Statistical continuum approach is used to predict effective conductivity of anisotropic random porous heterogeneous media using two-point correlation functions. Probability functions play a critical role in describing the statistical distribution of different constituents in a heterogeneous media. In this study a 3-dimensional two-point correlation function is utilized to characterize the anisotropic porous media of a Cathode materials to incorporate all the details of the microstructure. These correlation functions are then linked to the effective properties using homogenization relations. An anisotropioc Green’s function solution is used to solve the set of field equations. Examples in this study demonstrated how the model captured the anisotropy in effective conductivity of the random heterogeneous media. Predicted results showed the influence of microstructure on the effective conductivity tensor.
5
Tramsen, Halvor T., Stanislav N. Gorb, Hao Zhang, Poramate Manoonpong, Zhendong Dai, and Lars Heepe. "Inversion of friction anisotropy in a bio-inspired asymmetrically structured surface." Journal of The Royal Society Interface 15, no. 138 (January 2018): 20170629. http://dx.doi.org/10.1098/rsif.2017.0629.
Анотація:
Friction anisotropy is an important property of many surfaces that usually facilitate the generation of motion in a preferred direction. Such surfaces are very common in biological systems and have been the templates for various bio-inspired materials with similar tribological properties. So far friction anisotropy is considered to be the result of an asymmetric arrangement of surface nano- and microstructures. However, here we show by using bio-inspired sawtooth-structured surfaces that the anisotropic friction properties are not only controlled by an asymmetric surface topography, but also by the ratio of the sample–substrate stiffness, the aspect ratio of surface structures, and by the substrate roughness. Systematically modifying these parameters, we were able to demonstrate a broad range of friction anisotropies, and for specific sample–substrate combinations even an inversion of the anisotropy. This result highlights the complex interrelation between the different material and topographical parameters on friction properties and sheds new light on the conventional design paradigm of tribological systems. Finally, this result is also of great importance for understanding functional principles of biological materials and surfaces, as such inversion of friction anisotropy may correlate with gait pattern and walking behaviour in climbing animals, which in turn may be used in robotic applications.
6
Zhang, Qiankun, Rongjie Zhang, Jiancui Chen, Wanfu Shen, Chunhua An, Xiaodong Hu, Mingli Dong, Jing Liu, and Lianqing Zhu. "Remarkable electronic and optical anisotropy of layered 1T’-WTe2 2D materials." Beilstein Journal of Nanotechnology 10 (August 20, 2019): 1745–53. http://dx.doi.org/10.3762/bjnano.10.170.
Анотація:
Anisotropic 2D materials exhibit novel optical, electrical and thermoelectric properties that open possibilities for a great variety of angle-dependent devices. Recently, quantitative research on 1T’-WTe2 has been reported, revealing its fascinating physical properties such as non-saturating magnetoresistance, highly anisotropic crystalline structure and anisotropic optical/electrical response. Especially for its anisotropic properties, surging research interest devoted solely to understanding its structural and optical properties has been undertaken. Here we report quantitative, comprehensive work on the highly anisotropic, optical, electrical and optoelectronic properties of few-layer 1T’-WTe2 by azimuth-dependent reflectance difference microscopy, DC conductance measurements, as well as polarization-resolved and wavelength-dependent optoelectrical measurements. The electrical conductance anisotropic ratio is found to ≈103 for a thin 1T’-WTe2 film, while the optoelectronic anisotropic ratio is around 300 for this material. The polarization dependence of the photo-response is ascribed to the unique anisotropic in-plane crystal structure, consistent with the optical absorption anisotropy results. In general, 1T’-WTe2, with its highly anisotropic electrical and photoresponsivity reported here, demonstrates a route to exploit the intrinsic anisotropy of 2D materials and the possibility to open up new ways for applications of 2D materials for light polarization detection.
7
Chanda, Arnab, and Christian Callaway. "Tissue Anisotropy Modeling Using Soft Composite Materials." Applied Bionics and Biomechanics 2018 (2018): 1–9. http://dx.doi.org/10.1155/2018/4838157.
Анотація:
Soft tissues in general exhibit anisotropic mechanical behavior, which varies in three dimensions based on the location of the tissue in the body. In the past, there have been few attempts to numerically model tissue anisotropy using composite-based formulations (involving fibers embedded within a matrix material). However, so far, tissue anisotropy has not been modeled experimentally. In the current work, novel elastomer-based soft composite materials were developed in the form of experimental test coupons, to model the macroscopic anisotropy in tissue mechanical properties. A soft elastomer matrix was fabricated, and fibers made of a stiffer elastomer material were embedded within the matrix material to generate the test coupons. The coupons were tested on a mechanical testing machine, and the resulting stress-versus-stretch responses were studied. The fiber volume fraction (FVF), fiber spacing, and orientations were varied to estimate the changes in the mechanical responses. The mechanical behavior of the soft composites was characterized using hyperelastic material models such as Mooney-Rivlin’s, Humphrey’s, and Veronda-Westmann’s model and also compared with the anisotropic mechanical behavior of the human skin, pelvic tissues, and brain tissues. This work lays the foundation for the experimental modelling of tissue anisotropy, which combined with microscopic studies on tissues can lead to refinements in the simulation of localized fiber distribution and orientations, and enable the development of biofidelic anisotropic tissue phantom materials for various tissue engineering and testing applications.
8
Gurvich, Mark R. "On Characterization of Anisotropic Elastomeric Materials for Structural Analysis." Rubber Chemistry and Technology 77, no. 1 (March 1, 2004): 115–30. http://dx.doi.org/10.5254/1.3547805.
Анотація:
Abstract Existing efforts in constitutive modeling of elastomers are primarily focused on isotropic materials. On the other hand, anisotropic elastic models were successfully developed for traditional composites with relatively small strains, where geometrical non-linearity of deformation may be ignored. There are, however, certain materials where neither large deformation and incompressibility nor anisotropy of material stiffness may be neglected. This study proposes a general constitutive approach to model both hyperelasticity (including incompressibility) and full anisotropy of material deformation in structural analysis. According to the proposed approach, an original hyperelastic anisotropic body is modeled as a combination of two hypothetical components (hyperelastic isotropic and elastic anisotropic ones). The proposed approach shows simplicity and convenience of practical application along with high accuracy of analysis. It may be easily implemented in computational analysis of 2- and 3-D problems using commercially available FEA codes without additional programming efforts. Analytical and computational implementation of the approach is considered on representative examples of elastomeric structures and rubber-based composites. Analytical solutions are shown for examples of biaxial tension of composites and inflation of a toroidal anisotropic tube. FEA solutions are discussed on examples of an inflated anisotropic sphere and non-uniform deformation of a composite layer. Obtained results are discussed to emphasize benefits of the proposed approach. Finally, a methodology to evaluate material parameters using corresponding test results is considered according to the proposed approach.
9
Huang, Kai-xuan, Xiao-guang Gao, Bing-jie Hao, Xiu-xian Zhou, Zhan Li, Bao-wang Su, Xiao-kuan Li, et al. "Anisotropic imaging for the highly efficient crystal orientation determination of two-dimensional materials." Journal of Materials Chemistry C 7, no. 20 (2019): 5945–53. http://dx.doi.org/10.1039/c9tc00900k.
10
Хлыбов, А. А., та А. Л. Углов. "Об использовании параметров структурного шума при контроле поверхностными акустическими волнами Рэлея стали 20ГЛ в процессе упругопластического деформирования". Дефектоскопия 7 (липень 2021): 3–10. http://dx.doi.org/10.31857/s0130308221070010.
Анотація:
The relevance of the work is due to the need to create methods for determining the stress-strain state of acoustically anisotropic structural materials in the composition of technical objects operated in Arctic conditions. The features of using the acoustoelasticity phenomenon for materials with different values of acoustoelastic coefficients, acoustic anisotropy, and temperature dependence coefficients of acoustic parameters appearing in the calculation algorithms are analyzed. It is established that the existing approaches to accounting for temperature effects in a number of important cases lead to noticeable errors in determining mechanical stresses in the material of critical technical objects. At the same time, taking into account the temperature corrections is necessary for both biaxial (flat) and uniaxial stress states. The presence of anisotropy of the thermoacoustic coefficients of transverse waves for materials with anisotropy is experimentally shown. Refined calculation formulas for determining the one - and two-axis stress state of an anisotropic material, taking into account the anisotropy of the thermoacoustic coefficients of transverse waves, are proposed.
11
Wu, Feng Min, and Yuh Zhang Fang. "Anisotropic Growth of Metal Chains on Anisotropic Substrate." Solid State Phenomena 121-123 (March 2007): 1129–32. http://dx.doi.org/10.4028/www.scientific.net/ssp.121-123.1129.
Анотація:
Based on the exchange mechanism of metal islands growth on anisotropic metal surfaces, the growth processes of anisotropic Cu islands on the anisotropic Pd (110) surface are investigated by Monte Carlo simulations with realistic growth model and physical parameters. The anisotropic diffusion and anisotropic sticking of Cu adatoms are included in the simulation model after being considered the anisotropy of Pd (110) surface and compared to the experiments. It is found that the larger diffusion rate along the [110] channels of Pd (110) surface gives rise to a slower growth rate of Cu island in this direction, unless special effect of the anisotropic sticking is invoked. The simulation results show that the shape anisotropy of Cu islands is mainly due to the sticking anisotropy rather than the diffusion anisotropy.
12
Xie, Kunkun, Haopeng Song, and Cunfa Gao. "Electric and heat conduction across an elliptic cavity in an anisotropic medium." Mathematics and Mechanics of Solids 24, no. 10 (April 17, 2019): 3279–94. http://dx.doi.org/10.1177/1081286519840739.
Анотація:
It is well known that the anisotropy of materials will significantly affect heat conduction, and the corresponding results have been applied to the thermal analysis of materials. An elliptic cavity in a nonlinearly coupled anisotropic medium, on the other hand, is much more difficult to analyze. Based on the complex variable method, the problem of a two-dimensional elliptical cavity in an anisotropic material is analyzed in this paper, and the field distributions have been obtained in closed-form. The field intensity factors are discussed in detail. The results show that both the temperature and electric potential gradients at a crack tip are always perpendicular to the crack surface, regardless of the anisotropy and the nonlinearity in the constitutive equations and the arbitrariness of loading direction. These results provide a powerful tool to analyze the effective behavior and reliability of anisotropic materials with cavities.
13
Song, Honghua, Yixin Zhao, Yaodong Jiang, and Jiehao Wang. "Scale Effect on the Anisotropy of Acoustic Emission in Coal." Shock and Vibration 2018 (December 18, 2018): 1–11. http://dx.doi.org/10.1155/2018/8386428.
Анотація:
Acoustic emission (AE) in coal is anisotropic. In this paper, we investigate the microstructure-related scale effect on the anisotropic AE feature in coal at unconfined loading process. A series of coal specimens were processed with diameters of 25 mm, 38 mm, 50 mm, and 75 mm (height to diameter ratio of 2) and anisotropic angles of 0°, 15°, 30°, 45°, 60°, and 90°. The cumulative AE counts and energy dissipation increase with the specimen size, while the energy dissipation per AE count behaves in the opposite way. This may result from the increasing amount of both preexisting discontinuities and cracks (volume/number) needed for specimen failure and the lower energy dissipation AE counts generated by them. The effect of microstructures on the anisotropies of AE weakens with the increasing specimen size. The TRFD and its anisotropy reduce as the specimen size increases, and the reduction of fractal dimension is most pronounced at the anisotropic angle of 45°. The correlation between TRFD and cumulative AE energy in the specimens with different sizes are separately consistent with the negative exponential equation proposed by Xie and Pariseau. With the specimen size gain, the reduction of the TRFD weakens with the increasing amount of cumulative absolute AE energy.
14
Chen, Xinran, Jinsong Qian, Lei Zhang, and Jianming Ling. "Investigating the Combined Effects of Inherent and Stress-Induced Anisotropy on the Mechanical Behavior of Granular Materials Using Three-Dimensional Discrete Element Method." Mathematical Problems in Engineering 2020 (September 17, 2020): 1–16. http://dx.doi.org/10.1155/2020/7841824.
Анотація:
The three-dimensional discrete element method (DEM) was employed to investigate the combined effects of inherent and stress-induced anisotropy of granular materials. The particles were modeled following real particle shapes. Both isotropic and inherently anisotropic specimens were prepared, and then true triaxial numerical tests were conducted using different intermediate principle stress ratios (b). The results indicate that the oriented particles in the anisotropic specimens form strong contacts in their long axis direction in the early stages of shearing, which restrains the contraction of the specimens. As the strain increases, the oriented particles start to rotate and slide, which results in shorter contraction stages and fewer number of interparticle contacts with peak values compared to the isotropic specimens. In addition, the increase in b values aggravates the rotating and sliding of particles in the inherently anisotropic specimens and restrains the contraction of the granular and the increase of contact forces. As a result, the inherent anisotropy reduces the effects of stress-induced anisotropy on the mechanical behavior of granular materials.
15
Matsumura, Takashi, Shoichi Tamura, and Pedro José Arrazola. "Cutting Force Prediction in Drilling of Anisotropic Materials." Key Engineering Materials 504-506 (February 2012): 1365–70. http://dx.doi.org/10.4028/www.scientific.net/kem.504-506.1365.
Анотація:
The paper presents a predictive cutting force model in drilling of anisotropic materials. Three dimensional chip flow in drilling is interpreted as a piling up of the orthogonal cuttings in the planes containing the cutting velocities and the chip flow velocities. The cutting models in the chip flow are determined to calculate the cutting energy using the orthogonal cutting data. Then, the chip flow direction is determined to minimize the cutting energy. The cutting force can be predicted in the determined chip flow model. The cutting force with anisotropy in the material is modeled as the change in the shear stress on the shear plane. The shear stress changes with the rotation angle of the cutter. The cutting force prediction is verified in drilling of a titanium alloy. The anisotropic parameters are identified to minimize the model error between the measured and the predicted cutting forces. The periodical oscillation of the cutting force is also predicted by anisotropy in the shear stress.
16
Wu, Hong Ya, and Ji Zhou. "Negative Refraction in Indefinite Materials." Applied Mechanics and Materials 320 (May 2013): 143–49. http://dx.doi.org/10.4028/www.scientific.net/amm.320.143.
Анотація:
Negative refraction is a fantastic optical property and attracts more and more attentions. As first proposed, materials with negative permittivity and negative permeability simultaneously exhibit negative refraction. Recently, negative refraction was found in the indefinite medium based on the strong anisotropy of permittivity. In this paper, the theory of the negative refraction in the anisotropic materials and the research progress in recent years were reviewed.
17
Vladimirov, Ivaylo N., and Stefanie Reese. "Prediction of Springback in Unconstrained Bending by a Model for Evolving Elastic and Plastic Anisotropy." Key Engineering Materials 554-557 (June 2013): 2330–37. http://dx.doi.org/10.4028/www.scientific.net/kem.554-557.2330.
Анотація:
Sheet metals exhibit anisotropic plastic behavior due to the large plastic deformations that occur during the rolling of the sheet and which induce texture and are responsible for the initial anisotropy. There exist various possibilities to introduce plastic anisotropy into the finite element modelling of sheet metal forming. The initial yield anisotropy can be incorporated either through an anisotropic yield surface or directly by means of a crystallographic texture model. Here, one basically differentiates between empirical and phenomenological anisotropic yield function equations, where the anisotropy coefficients can be obtained from mechanical tests, and texture-based models the coefficients of which are directly determined based on experimentally obtained orientation distributions. Another type of anisotropy that can be usually found in anisotropic materials is the elastic anisotropy. In metal plasticity one often considers the effect of elastic anisotropy significantly smaller than the effect of plastic anisotropy. Consequently, elastic isotropic expressions are often used for elastic stored energy functions with anisotropic yield criteria. However, the influence of elastic anisotropy in the elastoplastic behavior can be very important especially during elastic recovery processes during unloading after forming and springback. This research focuses, therefore, on the study of the influence of elastic anisotropy on the amount of springback in bending processes such as e.g. unconstrained bending. We discuss a finite strain material model for evolving elastic and plastic anisotropy combining nonlinear isotropic and kinematic hardening. The evolution of elastic anisotropy is described by representing the Helmholtz free energy as a function of a family of evolving structure tensors. In addition, plastic anisotropy is modelled via the dependence of the yield surface on the same family of structure tensors. Exploiting the dissipation inequality leads to the interesting result that all tensor-valued internal variables are symmetric. Thus, the integration of the evolution equations can be efficiently performed by means of an algorithm that automatically retains the symmetry of the internal variables in every time step. The material model has been implemented as a user material subroutine UMAT into the commercial finite element software ABAQUS/Standard and has been applied to the simulation of springback of unconstrained bending.
18
Khraisheh, Marwan K. "An Investigation of Yield Potentials In Superplastic Deformation." Journal of Engineering Materials and Technology 122, no. 1 (May 14, 1999): 93–97. http://dx.doi.org/10.1115/1.482771.
Анотація:
Recent results (Khraisheh et al., 1995 and 1997) have indicated that superplastic materials exhibit a strong degree of anisotropy and that the plastic flow cannot be described by the isotropic von Mises flow rules. In this study, the yield potential for the model Pb-Sn superplastic alloy is constructed experimentally for different effective strain rates using combined tension/torsion tests. A generalized anisotropic “dynamic” yield function is also proposed to represent the experimentally constructed yield potentials. The anisotropic function is not only capable of describing the initial anisotropic state of the yield potential, it can also describe its evolution through the evolution of unit vectors defining the direction of anisotropy. The anisotropic yield function includes a set of material constants which determine the degree of deviation of the yield potential from the isotropic von Mises yield surface. It is shown that the anisotropic yield function successfully represents the experimental yield potentials, especially in the superplastic region. [S0094-4289(00)01401-8]
19
Ashour, Hamdy A. "A compressive strength criterion for anisotropic rock materials." Canadian Geotechnical Journal 25, no. 2 (May 1, 1988): 233–37. http://dx.doi.org/10.1139/t88-027.
Анотація:
This paper proposes a general compressive strength criterion for anisotropic rock materials under multiaxial states of stress. The proposed criterion is a generalization of the Von Mises' criterion for yielding of ductile metals, which has also been used previously as a strength criterion for brittle fracture in the spirit of both being limits of linear elastic behavior. The presently proposed criterion takes into consideration the effects of the confining pressure, the various stress components, and the material anisotropy on rock material failure in a multiaxial stress state. To verify the applicability of the proposed criterion, it has been used to construct the failure envelopes for several types of rock materials. Consequently, the constructed failure envelopes and the corresponding experimental results have been compared. In all cases, a close agreement with the experimental results has been achieved. This result demonstrates the versatility and applicability of the proposed strength criterion in representing the compressive strength behavior of anisotropic rock materials under complex multiaxial states of stress. Key words: strength, rock materials, anisotropy.
20
Cavalieri, Théo, Jean Boulvert, Gwénaël Gabard, Vicent Romero-García, Marie Escouflaire, Josselin Regnard, and Jean-Philippe Groby. "Graded and Anisotropic Porous Materials for Broadband and Angular Maximal Acoustic Absorption." Materials 13, no. 20 (October 16, 2020): 4605. http://dx.doi.org/10.3390/ma13204605.
Анотація:
The design of graded and anisotropic materials has been of significant interest, especially for sound absorption purposes. Together with the rise of additive manufacturing techniques, new possibilities are emerging from engineered porous micro-structures. In this work, we present a theoretical and numerical study of graded and anisotropic porous materials, for optimal broadband and angular absorption. Through a parametric study, the effective acoustic and geometric parameters of homogenized anisotropic unit cells constitute a database in which the optimal anisotropic and graded material will be searched for. We develop an optimization technique based on the simplex method that is relying on this database. The concepts of average absorption and diffuse field absorption coefficients are introduced and used to maximize angular acoustic absorption. Numerical results present the optimized absorption of the designed anisotropic and graded porous materials for different acoustic targets. The designed materials have anisotropic and graded effective properties, which enhance its sound absorption capabilities. While the anisotropy largely enhances the diffuse field absorbing when optimized at a single frequency, graded properties appear to be crucial for optimal broadband diffuse field absorption.
21
Nowicki, Michał, Roman Szewczyk, and Paweł Nowak. "Experimental Verification of Isotropic and Anisotropic Anhysteretic Magnetization Models." Materials 12, no. 9 (May 11, 2019): 1549. http://dx.doi.org/10.3390/ma12091549.
Анотація:
The anhysteretic magnetization curve is the key element of modeling magnetic hysteresis loops. Despite the fact that it is intensively exploited, known models of anhysteretic curve have not been verified experimentally. This paper presents the validation of four anhysteretic curve models considering four different materials, including isotropic, such as Mn-Zn soft ferrite, as well as anisotropic amorphous and nanocrystalline alloys. The presented results indicate that only the model that considers anisotropic energy is valid for a wide set of modern magnetic materials. The most suitable of the verified models is the anisotropic extension function-based model, which considers uniaxial anisotropy.
22
Ma, Ying, Olivier Gagliardini, Catherine Ritz, Fabien Gillet-Chaulet, Gaël Durand, and Maurine Montagnat. "Enhancement factors for grounded ice and ice shelves inferred from an anisotropic ice-flow model." Journal of Glaciology 56, no. 199 (2010): 805–12. http://dx.doi.org/10.3189/002214310794457209.
Анотація:
AbstractPolar ice is known to be one of the most anisotropic natural materials. For a given fabric the polycrystal viscous response is strongly dependent on the actual state of stress and strain rate. Within an ice sheet, grounded-ice parts and ice shelves have completely different stress regimes, so one should expect completely different impacts of ice anisotropy on the flow. The aim of this work is to quantify, through the concept of enhancement factors, the influence of ice anisotropy on the flow of grounded ice and ice shelves. For this purpose, a full-Stokes anisotropic marine ice-sheet flowline model is used to compare isotropic and anisotropic diagnostic velocity fields on a fixed geometry. From these full-Stokes results, we propose a definition of enhancement factors for grounded ice and ice shelves, coherent with the asymptotic models used for these regions. We then estimate realistic values for the enhancement factors induced by ice anisotropy for grounded ice and ice shelves.
23
Hyde, T. H., I. A. Jones, S. Peravali, W. Sun, J. G. Wang, and S. B. Leen. "Anisotropic Creep Behaviour of Bridgman Notch Specimens." Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications 219, no. 3 (July 1, 2005): 163–75. http://dx.doi.org/10.1243/146442005x10364.
Анотація:
A series of finite element anisotropic creep analyses of a Bridgman notch specimen have been performed. The anisotropic creep analysis is based on Hill's anisotropic yield model and the Norton creep law. An anisotropic parameter, p, is defined in order to quantify the degree of bulk material anisotropy which exists in a weld metal. The effects of p and the Norton stress exponent, n, on the stationary-state stresses, at the minimum cross-section of the notch, are presented. The material constants were chosen to include the practical range for engineering materials. Indications of the practical application of anisotropic analyses to welds are given.
24
Lyamina, Elena, Nataliya Kalenova, and Dinh Kien Nguyen. "Influence of Plastic Anisotropy on the Limit Load of an Overmatched Cracked Tension Specimen." Symmetry 12, no. 7 (July 1, 2020): 1079. http://dx.doi.org/10.3390/sym12071079.
Анотація:
Plastic anisotropy is a common property of many metallic materials. This property affects many aspects of structural analysis and design. In contrast to the isotropic case, there is a great variety of yield criteria proposed for anisotropic materials. Moreover, even if one specific yield criterion is selected, several constitutive parameters are involved in it. Therefore, parametric analysis of structures made of anisotropic materials is quite cumbersome. The present paper demonstrates the effect of the constitutive parameters involved in Hill’s quadratic yield criterion on the upper bound limit load for weld stretched overmatched tension specimens containing a crack of arbitrary shape, assuming that the crack is located inside the weld. Different sets of the constitutive parameters are involved in the yield criteria for weld and base materials. Since the limit load is an input parameter of many flaw assessment procedures, the final result of the present paper shows that it is necessary to take into account plastic anisotropy in these procedures. It is worthy of note that the limit load is involved in the flaw assessment procedures in combination with the stress and strain fields near the tip of a crack. In anisotropic materials, these fields may become non-symmetric even under symmetric loading. This behavior affects the propagation of cracks.
25
Kowatari, Munehiko, Sho Nishino, Kristine Marie D. Romallosa, Hiroshi Yoshitomi, Yoshihiko Tanimura, and Tetsuya Ohishi. "EXPERIMENTAL DETERMINATION OF ANISOTROPIC EMISSION OF NEUTRONS FROM 252CF NEUTRON SOURCE WITH THE SPHERICAL PROTECTION CASE." Radiation Protection Dosimetry 189, no. 4 (May 2020): 436–43. http://dx.doi.org/10.1093/rpd/ncaa064.
Анотація:
Abstract The anisotropic emission of neutrons from a cylindrical X1 252Cf source with the spherical external casing was experimentally determined. The influence of metal materials and shapes of the external casing to the anisotropy factor, FI(θ), was assessed by the Monte Carlo calculation, before performing the measurement. The results of the calculation implied that light- and spherical-shaped external casing decreases the anisotropic emission of neutrons from a cylindrical source and the nature of the material does not affect the anisotropic emission to a large extent. The experimental results obtained when a spherical-shaped aluminum protection case was employed also revealed that the anisotropy factor was close to 1.0 with a wide zenith angle range. Considering the source handling and measures against mechanical impact to the source, we designed an SUS304-made spherical protection case for a renovated source delivering apparatus. With the SUS304-made spherical protection case, the measured anisotropy factor FI(90) was determined to be 1.002 ± 0.002 (k = 1). Results from the experiments also indicated that the measured anisotropy factor has a flat distribution from 55 to 125° with zenith angle.
26
Ishigami, Genya, Jim Overholt, and Karl Iagnemma. "Multi-material Anisotropic Friction Wheels for Omnidirectional Ground Vehicles." Abstracts of the international conference on advanced mechatronics : toward evolutionary fusion of IT and mechatronics : ICAM 2010.5 (2010): 658–62. http://dx.doi.org/10.1299/jsmeicam.2010.5.658.
27
Chen, Liping, Sui Wang, Bin Chen, Xiaokai Niu, Guogang Ying, and Bo Wu. "Formulation of Anisotropic Strength Criterion for Geotechnical Materials." Advances in Civil Engineering 2020 (September 7, 2020): 1–10. http://dx.doi.org/10.1155/2020/8825816.
Анотація:
A new nonlinear unified strength (NUS) criterion is obtained based on the spatially mobilized plane (SMP) criterion and Mises criterion. New criterion is a series of smooth curves between SMP curved triangle and Mises circle in the π plane and thereby unifies the strength criteria. The new criterion can reflect the effect of the intermediate principal stress and consider the strength nonlinearity of a material. Based on the fabric tensor, the anisotropic parameter A is defined, and the anisotropic equation is proposed and introduced into the NUS criterion to form a nonlinear unified anisotropic strength criterion. The new criterion can be used to predict the strength variation of granular materials and cohesive materials under three-dimensional stress and can present the strength anisotropy of the geomaterials. The validity of the new criterion was checked using rock and soil materials. It is shown that the prediction results for the criterion agree well with the test data.
28
Jun, Jihyun, Young-Dae Shim, and Kyung-Young Jhang. "Stress Estimation Using the Acoustoelastic Effect of Surface Waves in Weak Anisotropic Materials." Applied Sciences 10, no. 1 (December 24, 2019): 169. http://dx.doi.org/10.3390/app10010169.
Анотація:
This paper proposes a novel stress measurement method using the acoustoelastic effect of surface wave to estimate the stress of a homogeneous material plate with orthogonal anisotropy, in which the surface wave velocities are measured in three different directions before and after loading stress. The effectiveness of the proposed method was verified by numerical simulations and experiments. For the simulations, the surface wave velocities in three directions were obtained from a conventional perturbation model for weak anisotropic materials. The simulation results showed that the stress estimation error was less than 3% for an anisotropic rate up to 2% under stress conditions up to 90 MPa. Two specimens were prepared for the experiments, one was almost isotropic and another that had a relatively larger anisotropy rate of 2.6%. Then, the stresses loaded by a tensile test machine were estimated. The results showed good agreement with the given stresses for both specimens. These results confirm that the proposed method can be applied to estimate the surface stress state in anisotropic material plates. The proposed method is simple, practical, and is expected to be useful for monitoring changes of surface stress before and after machining such as the punching or bending of plate.
29
Cheng, Jiao, and Qidong Zhang. "Optical, Electronic Properties and Anisotropy in Mechanical Properties of “X” Type Carbon Allotropes." Materials 13, no. 9 (May 1, 2020): 2079. http://dx.doi.org/10.3390/ma13092079.
Анотація:
Based on first-principle calculations, the mechanical anisotropy and the electronic and optical properties of seven kinds of carbon materials are investigated in this work. These seven materials have similar structures: they all have X-type structures, with carbon atoms or carbon clusters at the center and stacking towards the space. A calculation of anisotropy shows that the order of elastic anisotropy in terms of the shear modulus, Young’s modulus and Poisson’s ratio of these seven carbon materials with similar structure is diamond < supercubane < T carbon < Y carbon < TY carbon < cubane-diyne < cubane-yne. As these seven carbon materials exhibit cubic symmetry, Young’s modulus has the same anisotropy in some major planes, so the order of elastic anisotropy in the Young’s modulus of these seven main planes is (111) plane < (001) plane = (010) plane = (100) plane < (011) plane = (110) plane = (101) plane. It is also due to the fact that their crystal structure has cubic symmetry that the elastic anisotropy in the shear modulus and the Poisson’s ratio of these seven carbon materials on the seven major planes are the same. Among the three propagation directions of [100], [110], and [111], the [110] propagation direction’s anisotropic ratio of the sound velocity of TY carbon is the largest, while the anisotropic ratio of the sound velocity of cubane-diyne on the [100] propagation direction is the smallest. In addition, not surprisingly, the diamond has the largest Debye temperature, while the TY carbon has the smallest Debye temperature. Finally, TY carbon, T carbon and cubane-diyne are also potential semiconductor materials for photoelectric applications owing to their higher or similar absorption coefficients to GaAs in the visible region.
30
Badreddine, Houssem, and Khemais Saanouni. "On the full coupling of plastic anisotropy and anisotropic ductile damage under finite strains." International Journal of Damage Mechanics 26, no. 7 (March 3, 2016): 1080–123. http://dx.doi.org/10.1177/1056789516635729.
Анотація:
In this work, thermodynamically consistent, non-associative and fully anisotropic elastoplastic constitutive equations strongly coupled with ductile anisotropic damage developed in previous work are used to study the responses of the proposed model under various simple and complex loading paths. First, the complete set of the fully coupled non-associative constitutive equations based on the rotated frame formulation (RFF) for finite strains is summarized and shortly discussed. Then, the effect of the rotating frame in the model response is analyzed on the light of typical loading paths. The influence of the induced plastic anisotropies on the evolution of the anisotropic ductile damage is investigated. Finally, the responses of the model for non-proportional loading paths are studied, compared and discussed with respect to the initial and induced anisotropies of the plastic flow and the ductile damage evolution as well as with respect to the rotating frame choice.
31
Li, Lin, Jin Yang, Xiu Qing Qian, Hai Xia Zhang, and Zhi Cheng Liu. "The Numerical Study on Errors of Stress in Anisotropic Linear Elastic Material when Simplified as Orthogonal one." Applied Mechanics and Materials 275-277 (January 2013): 3–6. http://dx.doi.org/10.4028/www.scientific.net/amm.275-277.3.
Анотація:
Keywords: strain, stress, material constants, constitutive equation, anisotropy. Abstract. If the material is anisotropic, there are differences in stress distribution under the same boundary conditions when it was simplified as an orthotropic material. We established a simple finite element model for rectangular perforated planar material, in which one side was fixed, the opposite side was loaded with uniform force, and the other sides were set free. Based on this model we studied the difference of distribution of stress between anisotropic material and its simplified form, orthotropic material. The results showed differences in some cases quite large, the maximum relative error of extreme stress can reach 341%. In conclusions, this study does not support that the complex anisotropic materials are simplified to orthotropic materials. If researchers only concern the location of extreme stress, this study does not deny that the complex anisotropic materials can be simplified to orthotropic one.
32
Tovstyuk, C. C. "Thermodynamic functions of quantum electron gas in strongly anisotropic materials." Functional materials 23, no. 1 (March 15, 2016): 83–87. http://dx.doi.org/10.15407/fm23.01.083.
33
Takahashi, Ribeka, David T. Fullwood, Travis M. Rampton, Darrell J. Skousen, Brent L. Adams, and Christopher A. Mattson. "Hybrid Bishop-Hill model combined finite element analysis for elastic-yield limited design." Engineering Computations 32, no. 6 (August 3, 2015): 1814–36. http://dx.doi.org/10.1108/ec-06-2014-0130.
Анотація:
Purpose – Microstructure-sensitive design (MSD), for optimal performance of engineering components that are sensitive to material anisotropy, has largely been confined to the realm of theory. The purpose of this paper is to insert the MSD framework into a finite element environment in order to arrive at a practical tool for improved selection and design of materials for critical engineering situations. Design/methodology/approach – This study applies the recently developed Hybrid Bishop-Hill (HBH) model to map the yield surface of anisotropic oxygen free electronic copper. Combining this information with the detailed local stresses determined via finite element analysis (FEA), a “configurational yield stress” is determined for the entire component. By varying the material choice/processing conditions and selecting the directionality of anisotropy, an optimal configuration is found. Findings – The paper provides a new FEA-based framework for MSD for yield-limited situations. The approach identified optimal directionality and processing configurations for three engineering situations that are particularly sensitive to material anisotropy. Research limitations/implications – The microstructure design space for this study is limited to a selection of eight copper materials produced by a range of processing methods, but is generalizable to many materials that exhibit anisotropic behavior. Originality/value – The introduction of MSD methodology into a finite element environment is a first step toward a comprehensive designer toolkit for exploiting the anisotropy of general materials (such as metals) in a way that is routinely undertaken in the world of fiber-based composite materials. While the gains are not as sizeable (due to the less-extreme anisotropy), in many applications they may be extremely important.
34
Hinrichs, Karsten, and Timur Shaykhutdinov. "Polarization-Dependent Atomic Force Microscopy–Infrared Spectroscopy (AFM-IR): Infrared Nanopolarimetric Analysis of Structure and Anisotropy of Thin Films and Surfaces." Applied Spectroscopy 72, no. 6 (April 13, 2018): 817–32. http://dx.doi.org/10.1177/0003702818763604.
Анотація:
Infrared techniques enable nondestructive and label-free studies of thin films with high chemical and structural contrast. In this work, we review recent progress and perspectives in the nanoscale analysis of anisotropic materials using an extended version of the atomic force microscopy–infrared (AFM-IR) technique. This advanced photothermal technique, includes polarization control of the incoming light and bridges the gap in IR spectroscopic analysis of local anisotropic material properties. Such local anisotropy occurs in a wide range of materials during molecular nucleation, aggregation, and crystallization processes. However, analysis of the anisotropy in morphology and structure can be experimentally and theoretically demanding as it is related to order and disorder processes in ranges from nanoscopic to macroscopic length scales, depending on preparation and environmental conditions. In this context IR techniques can significantly assist as IR spectra can be interpreted in the framework of optical models and numerical calculations with respect to both, the present chemical conditions as well as the micro- and nanostructure. With these extraordinary analytic possibilities, the advanced AFM-IR approach is an essential puzzle piece in direction to connect nanoscale and macroscale anisotropic thin film properties experimentally. In this review, we highlight the analytic possibilities of AFM-IR for studies on nanoscale anisotropy with a set of examples for polymer, plasmonic, and polaritonic films, as well as aggregates of large molecules and proteins.
35
BOTTAUSCIO, ORIANO, VALERIA CHIADÒ PIAT, MICHELA ELEUTERI, LUCA LUSSARDI, and ALESSANDRA MANZIN. "DETERMINATION OF THE EQUIVALENT ANISOTROPY PROPERTIES OF POLYCRYSTALLINE MAGNETIC MATERIALS: THEORETICAL ASPECTS AND NUMERICAL ANALYSIS." Mathematical Models and Methods in Applied Sciences 23, no. 07 (April 2, 2013): 1217–33. http://dx.doi.org/10.1142/s0218202513500073.
Анотація:
The aim of this paper is the determination of the equivalent anisotropy properties of polycrystalline magnetic materials, modeled as an assembly of monocrystalline grains with a stochastic spatial distribution of easy axes. The theory of Γ-convergence is here adopted to homogenize the anisotropic contribution in the energy functional and derive the equivalent anisotropy properties. The reliability of this approach is investigated focusing on the computation of the static hysteresis loops of polycrystalline magnetic thin films, starting from the numerical integration of the Landau–Lifshitz–Gilbert equation.
36
Chien, W. Y., J. Pan, and S. C. Tang. "Modified Anisotropic Gurson Yield Criterion for Porous Ductile Sheet Metals." Journal of Engineering Materials and Technology 123, no. 4 (July 25, 2000): 409–16. http://dx.doi.org/10.1115/1.1395023.
Анотація:
The influence of plastic anisotropy on the plastic behavior of porous ductile materials is investigated by a three-dimensional finite element analysis. A unit cell of cube containing a spherical void is modeled. The Hill quadratic anisotropic yield criterion is used to describe the matrix normal anisotropy and planar isotropy. The matrix material is first assumed to be elastic perfectly plastic. Macroscopically uniform displacements are applied to the faces of the cube. The finite element computational results are compared with those based on the closed-form anisotropic Gurson yield criterion suggested in Liao et al. 1997, “Approximate Yield Criteria for Anisotropic Porous Ductile Sheet Metals,” Mech. Mater., pp. 213–226. Three fitting parameters are suggested for the closed-form yield criterion to fit the results based on the modified yield criterion to those of finite element computations. When the strain hardening of the matrix is considered, the computational results of the macroscopic stress-strain behavior are in agreement with those based on the modified anisotropic Gurson’s yield criterion under uniaxial and equal biaxial tensile loading conditions.
37
Abu-Farha, Fadi K., and Marwan K. Khraisheh. "Modeling of Anisotropic Deformation in Superplastic Sheet Metal Stretching." Journal of Engineering Materials and Technology 127, no. 1 (January 1, 2005): 159–64. http://dx.doi.org/10.1115/1.1839216.
Анотація:
Currently available models describing superplastic deformation are mostly based on uniaxial tensile test data and assume isotropic behavior, thus leading to limited predictive capabilities of material deformation and failure. In this work we present a multi-axial microstructure-based constitutive model that describes the anisotropic superplastic deformation within the continuum theory of viscoplasticity with internal variables. The model accounts for microstructural evolution and employs a generalized anisotropic dynamic yield function. The anisotropic yield function can describe the evolution of the initial state of anisotropy through the evolution of unit vectors defining the direction of anisotropy during deformation. The generalized model is then reduced to the plane stress condition to simulate sheet metal stretching in superplastic blow forming using pressurized gas. Different ratios of biaxial stretching were investigated, including the case simulating the uniaxial loading condition, where the model successfully captured the uniaxial experimental data. The model is also used to develop a new forming pressure profile that accounts for anisotropy and microstructural evolution.
38
Gouin, C., T. Bonnaire, and N. Aghanim. "Shape and connectivity of groups and clusters: Effect of the dynamical state and accretion history." Astronomy & Astrophysics 651 (July 2021): A56. http://dx.doi.org/10.1051/0004-6361/202140327.
Анотація:
Matter distribution around clusters is highly anisotropic because clusters are the nodes of the cosmic web. The shape of the clusters and the number of filaments to which they are connected, that is, their connectivity, is thought to reflect their level of anisotropic matter distribution and must in principle be related to their physical properties. We investigate the effect of the dynamical state and the formation history on both the morphology and local connectivity of about 2400 groups and clusters of galaxies from the large hydrodynamical simulation IllustrisTNG at z = 0. We find that the mass of groups and clusters mainly affects the geometry of the matter distribution: Massive halos are significantly more elliptical and are more strongly connected to the cosmic web than low-mass halos. Beyond the mass-driven effect, ellipticity and connectivity are correlated and are imprints of the growth rate of groups and clusters. Both anisotropy measures appear to trace different dynamical states, such that unrelaxed groups and clusters are more elliptical and more connected than relaxed ones. This relation between matter anisotropies and dynamical state is the sign of different accretion histories. Relaxed groups and clusters have mostly been formed a long time ago and are slowly accreting matter at the present time. They are highly spherical and weakly connected to their environment, mostly because they had enough time to relax and thus lost the connection with their preferential directions of accretion and merging. In contrast, late-formed unrelaxed objects are highly anisotropic with strong connectivities and ellipticities. These groups and clusters are in their formation phase and must be strongly affected by the infalling of materials from filaments.
39
Sevillano, J. Gil. "Toughness and Fatigue Crack Growth Rate of Textured Metals." Textures and Microstructures 12, no. 1-3 (January 1, 1990): 77–87. http://dx.doi.org/10.1155/tsm.12.77.
Анотація:
The influence of anisotropy of crystallographic origin on both fracture toughness and the rate of stage-II ductile fatigue crack growth in textured metals is discussed in terms of a plane-strain small geometry change solution for plastic non-hardening materials (a Prandtl-type slip-line field solution accounting for anisotropy). Results corresponding to FCC or BCC metals sliding, respectively, on {111} 〈110〉 or {110} 〈111〉 systems are presented. Remarkable effects of both texture toughening and fatigue crack growth rate anisotropy are predicted. Stronger effects are anticipated in more anisotropic metals (HCP).
40
Felippa, Carlos A., and Eugenio On˜ate. "Volumetric Constraint Models for Anisotropic Elastic Solids." Journal of Applied Mechanics 71, no. 5 (September 1, 2004): 731–34. http://dx.doi.org/10.1115/1.1748318.
Анотація:
We study three “incompressibility flavors” of linearly elastic anisotropic solids that exhibit volumetric constraints: isochoric, hydroisochoric, and rigidtropic. An isochoric material deforms without volume change under any stress system. An hydroisochoric material does so under hydrostatic stress. A rigidtropic material undergoes zero deformations under a certain stress pattern. Whereas the three models coalesce for isotropic materials, important differences appear for anisotropic behavior. We find that isochoric and hydroisochoric models under certain conditions may be hampered by unstable physical behavior. Rigidtropic models can represent semistable physical materials of arbitrary anisotropy while including isochoric and hydroisochoric behavior as special cases.
41
Daghash, Shaden, Phillip Servio, and Alejandro Rey. "First-Principles Elastic and Anisotropic Characteristics of Structure-H Gas Hydrate under Pressure." Crystals 11, no. 5 (April 24, 2021): 477. http://dx.doi.org/10.3390/cryst11050477.
Анотація:
Evaluating gas hydrates properties contributes valuably to their large-scale management and utilization in fundamental science and applications. Noteworthy, structure-H (sH) gas hydrate lacks a comprehensive characterization of its structural, mechanical, and anisotropic properties. Anisotropic and pressure dependent properties are crucial for gas hydrates’ detection and recovery studies. The objective of this work is the determination of pressure-dependent elastic constants and mechanical properties and the direction-dependent moduli of sH gas hydrates as a function of guest composition. First-principles DFT computations are used to evaluate the mechanical properties, anisotropy, and angular moduli of different sH gas hydrates under pressure. Some elastic constants and moduli increase more significantly with pressure than others. This introduces variations in sH gas hydrate’s incompressibility, elastic and shear resistance, and moduli anisotropy. Young’s modulus of sH gas hydrate is more anisotropic than its shear modulus. The anisotropy of sH gas hydrates is characterized using the unit cell elastic constants, anisotropy factors, and the angular dependent moduli. Structure-properties composition correlations are established as a function of pressure. It is found that compressing filled sH gas hydrates increases their moduli anisotropy. Differences in atomic bonding across a crystal’s planes can be expected in anisotropic structures. Taken together the DFT-based structure–properties–composition relations for sH gas hydrates provide novel and significant material physics results for technological applications.
42
Dabat, Thomas, Arnaud Mazurier, Fabien Hubert, Emmanuel Tertre, Brian Grégoire, Baptiste Dazas, and Eric Ferrage. "Mesoscale Anisotropy in Porous Media Made of Clay Minerals. A Numerical Study Constrained by Experimental Data." Materials 11, no. 10 (October 13, 2018): 1972. http://dx.doi.org/10.3390/ma11101972.
Анотація:
The anisotropic properties of clay-rich porous media have significant impact on the directional dependence of fluids migration in environmental and engineering sciences. This anisotropy, linked to the preferential orientation of flat anisometric clay minerals particles, is studied here on the basis of the simulation of three-dimensional packings of non-interacting disks, using a sequential deposition algorithm under a gravitational field. Simulations show that the obtained porosities fall onto a single master curve when plotted against the anisotropy value. This finding is consistent with results from sedimentation experiments using polytetrafluoroethylene (PTFE) disks and subsequent extraction of particle anisotropy through X-ray microtomography. Further geometrical analyses of computed porous media highlight that both particle orientation and particle aggregation are responsible of the evolution of porosity as a function of anisotropy. Moreover, morphological analysis of the porous media using chord length measurements shows that the anisotropy of the pore and solid networks can be correlated with particle orientation. These results indicate that computed porous media, mimicking the organization of clay minerals, can be used to shed light on the anisotropic properties of fluid transfer in clay-based materials.
43
Bartkowiak, Tomasz, Johan Berglund, and Christopher A. Brown. "Multiscale Characterizations of Surface Anisotropies." Materials 13, no. 13 (July 7, 2020): 3028. http://dx.doi.org/10.3390/ma13133028.
Анотація:
Anisotropy can influence surface function and can be an indication of processing. These influences and indications include friction, wetting, and microwear. This article studies two methods for multiscale quantification and visualization of anisotropy. One uses multiscale curvature tensor analysis and shows anisotropy in horizontal coordinates i.e., topocentric. The other uses multiple bandpass filters (also known as sliding bandpass filters) applied prior to calculating anisotropy parameters, texture aspect ratios (Str) and texture directions (Std), showing anisotropy in horizontal directions only. Topographies were studied on two milled steel surfaces, one convex with an evident large scale, cylindrical form anisotropy, the other nominally flat with smaller scale anisotropies; a µEDMed surface, an example of an isotropic surface; and an additively manufactured surface with pillar-like features. Curvature tensors contain the two principal curvatures, i.e., maximum and minimum curvatures, which are orthogonal, and their directions, at each location. Principal directions are plotted for each calculated location on each surface, at each scale considered. Histograms in horizontal coordinates show altitude and azimuth angles of principal curvatures, elucidating dominant texture directions at each scale. Str and Std do not show vertical components, i.e., altitudes, of anisotropy. Changes of anisotropy with scale categorically failed to be detected by traditional characterization methods used conventionally. These multiscale methods show clearly in several representations that anisotropy changes with scale on actual surface measurements with markedly different anisotropies.
44
Welemane, Hélène, Cristina Goidescu, Djimédo Kondo, Olivier Pantalé, and Moussa Karama. "Brittle Damage in Initially Anisotropic Materials: A Model Accounting for the Induced Anisotropy and Unilateral Effects." Applied Mechanics and Materials 784 (August 2015): 173–78. http://dx.doi.org/10.4028/www.scientific.net/amm.784.173.
Анотація:
A new micromechanical modelling approach for brittle damage in initially orthotropic materials is presented. The proposed strain-based energy formulation allows to derive a fully anisotropic multilinear model for microcracked materials with arbitrary oriented defects. The thermodynamics framework provides a standard procedure for the damage evolution law. The new model explicitly accounts for the interaction between primary and induced anisotropies. Moreover, the very challenging issue of opening-closure effects (unilateral behavior) is addressed in this framework.
45
YONEDA, KEISHI, AKIO YONEZU, HIROYUKI HIRAKATA, and KOHJI MINOSHIMA. "ESTIMATION OF ANISOTROPIC PLASTIC PROPERTIES OF ENGINEERING STEELS FROM SPHERICAL IMPRESSIONS." International Journal of Applied Mechanics 02, no. 02 (June 2010): 355–79. http://dx.doi.org/10.1142/s1758825110000536.
Анотація:
This study proposes a method of reverse analysis to estimate the anisotropic plastic properties of engineering steels by spherical indentation. The method takes into consideration materials that obey the work-hardening law and show in-plane anisotropic yield stress. Finite element analysis was first carried out to compute the indentation behavior of such materials, showing that a permanent impression exhibited an anisotropic shape which was strongly dependent on the orthotropic axis. Based on the anisotropy of the impression geometry, we developed a simple approach to determine the yield stress, work-hardening exponent and yield stress ratio. The approach consists of several functions related to the parameters of two impression geometries, produced by dual spherical indentations with different indentation forces. Since the present method uses only two impression geometries and does not necessitate indentation force — displacement curves (indentation curves), it is a particularly useful technique to evaluate "indistinguishable materials" which are special sets of materials with distinct plastic properties, yet yield almost identical indentation curves.
46
Bedra, Randa, Sami Bedra, and Tarek Fortaki. "Analysis of elliptical-disk microstrip patch printed on isotropic or anisotropic substrate materials." International Journal of Microwave and Wireless Technologies 8, no. 2 (November 13, 2014): 251–55. http://dx.doi.org/10.1017/s1759078714001433.
Анотація:
This paper presents a simple approach for accurate determination of the resonant frequency of an elliptical microstrip patch printed on isotropic or anisotropic substrate materials. In this approach, some modifications are made to account for fringe fields, dispersion effects, and losses by calculating effective dimensions, effective permittivity of anisotropy in the layer, and effective loss tangent, respectively. The theoretical resonant frequency results are in very good agreement with the experimental results reported elsewhere. Numerical results show that the change in the resonant frequency of the antenna is due primarily to a small disturbance of the substrate's nature. Then the effect of the uniaxial anisotropic materials is a significant parameter and most essential on the microstrip antenna characterization.
47
Du, Guangbo, Nina Liu, Zhao Xia, and Xin Kang. "Laboratory Investigation on the Stress-Dependent Anisotropic Shear Wave Velocity (Vs) and Coefficient of Lateral Earth Pressure at Rest (K0) of Granular Materials." Advances in Civil Engineering 2021 (April 22, 2021): 1–13. http://dx.doi.org/10.1155/2021/6639178.
Анотація:
The stress-dependent K0, Vs, and Vs anisotropy and their correlations with sand for 1D consolidation stress were tested with a custom-designed floating-wall consolidometer-type Bender Element (BE) testing apparatus. K0 of a soil sample was calculated using stress measurements through soil pressure transducers installed at the midsection of the consolidometer. The Vs and Vs anisotropy were measured by the bender elements installed in three orthogonal directions in the consolidometer, i.e., vh, hv, and hh. Granular soils with different sizes and shapes were tested. The effects of the stress level, overconsolidation ratio (OCR), particle size and shape on the Vs anisotropy, and K0 of the granular soils during one-dimensional consolidation were investigated. The laboratory investigations suggested (1) the K0 showed a constant value during loading, while it increased as the OCR increased during unloading, (2) soils with smaller particle sizes, rough surfaces, and angular geometry tended to have a lower value of K0, and vice versa, (3) both the anisotropic stress state and the anisotropic fabric (geometry) could lead to the Vs anisotropy, but the Vs anisotropy was manifested due to the horizontal stress-lock during unloading stage, and (4) the published correlation between Vs and K0 was modified by introducing the influence of the OCR, which could effectively reduce the variation and improve the prediction accuracy. Therefore, the modified correlation could be used as a robust approach to estimate K0 for both normally consolidated and highly overly consolidated granular soils.
48
CLEMENTS, DAVID L. "ON AN ANTIPLANE CRACK PROBLEM FOR FUNCTIONALLY GRADED ELASTIC MATERIALS." ANZIAM Journal 52, no. 1 (July 2010): 69–86. http://dx.doi.org/10.1017/s1446181111000551.
Анотація:
AbstractThis paper examines an antiplane crack problem for a functionally graded anisotropic elastic material in which the elastic moduli vary quadratically with the spatial coordinates. A solution to the crack problem is obtained in terms of a pair of integral equations. An iterative solution to the integral equations is used to examine the effect of the anisotropy and varying elastic moduli on the crack tip stress intensity factors and the crack displacement.
49
Welzel, Udo, and Eric J. Mittemeijer. "The analysis of homogeneously and inhomogeneously anisotropic microstructures by X-ray diffraction." Powder Diffraction 20, no. 4 (December 2005): 376–92. http://dx.doi.org/10.1154/1.2138066.
Анотація:
The microstructure of materials is generally, macroscopically, anisotropic and/or inhomogeneous. Traditional diffraction analyses do not take into account this anisotropy and/or inhomogeneity of microstructural features. Thus obtained results can be incomplete, ambiguous, or even erroneous. In this work instrumental requirements (application of parallel beam diffractometers with X-ray lenses or X-ray mirrors and parallel-plate collimators in the laboratory and at synchrotron beam lines) and methodological approaches for the diffraction analysis of anisotropic and inhomogeneous microstructures have been discussed and have been illustrated on the basis of two experimental examples: analysis of the anisotropic nature of the structural imperfection of a sputterdeposited Ti3Al layer and analysis of the anisotropic and inhomogeneous elastic grain interaction in a sputter-deposited Ni layer.
50
Buchen, Johannes, Wolfgang Sturhahn, Takayuki Ishii та Jennifer M. Jackson. "Vibrational anisotropy of <i>δ</i>-(Al,Fe)OOH single crystals as probed by nuclear resonant inelastic X-ray scattering". European Journal of Mineralogy 33, № 4 (17 серпня 2021): 485–502. http://dx.doi.org/10.5194/ejm-33-485-2021.
Анотація:
Abstract. The formation of high-pressure oxyhydroxide phases spanned by the components AlOOH–FeOOH–MgSiO2(OH)2 in experiments suggests their capability to retain hydrogen in Earth's lower mantle. Understanding the vibrational properties of high-pressure phases provides the basis for assessing their thermal properties, which are required to compute phase diagrams and physical properties. Vibrational properties can be highly anisotropic, in particular for materials with crystal structures of low symmetry that contain directed structural groups or components. We used nuclear resonant inelastic X-ray scattering (NRIXS) to probe lattice vibrations that involve motions of 57Fe atoms in δ-(Al0.87Fe0.13)OOH single crystals. From the recorded single-crystal NRIXS spectra, we calculated projections of the partial phonon density of states along different crystallographic directions. To describe the anisotropy of central vibrational properties, we define and derive tensors for the partial phonon density of states, the Lamb–Mössbauer factor, the mean kinetic energy per vibrational mode, and the mean force constant of 57Fe atoms. We further show how the anisotropy of the Lamb–Mössbauer factor can be translated into anisotropic displacement parameters for 57Fe atoms and relate our findings on vibrational anisotropy to the crystal structure of δ-(Al,Fe)OOH. As a potential application of single-crystal NRIXS at high pressures, we discuss the evaluation of anisotropic thermal stresses in the context of elastic geobarometry for mineral inclusions. Our results on single crystals of δ-(Al,Fe)OOH demonstrate the sensitivity of NRIXS to vibrational anisotropy and provide an in-depth description of the vibrational behavior of Fe3+ cations in a crystal structure that may motivate future applications of NRIXS to study anisotropic vibrational properties of minerals.