Composite Plane Research Articles

Comparison of the Optical Lock-in Thermography using the Reflection Mode and the Transmission Mode

Optical lock-in thermography is a non-destructive testing method. The surface of the sample is excited using the thermal waves and the response is recorded by the thermal camera. This image thermal sequence is processed using the image processing method named lock-in method. Optical lock-in thermography can be used to detect cracks and damages in metal or composite material. Two position modes are used: the reflection and the transmission mode. In this paper, are compared these two modes. An experiment is carried out on a printed composite plane with the square blinded holes placed in the different depths below the surface. The phase images are created using the lock-in method for both position modes. The results are compared and the advantages and the disadvantage of these position modes find out.

DANCE AS A MARKER OF NATURAL CYCLES CHANGE IN TERRY PRATCHETT’S FANTASY NOVELS

Against the background of a widespread tendency to diminish the sacred meaning of ritual actions, Terry Pratchett’s strive to shed light on the archetypal principles of mythological consciousness in contemporary folklore makes it possible to restorethe connection of the old rites, which have lost their original sense, with the worldview bases of modern society and to reacralize the profane. The Elements of mythological consciousness, manifested in ritual actions inherent in the modern functioning of English folklore, play a meaningful and compositional role in Terry Pratchett’s novels «The Reaper» (1991), «Lords and Ladies» (1992) and «Wintersmith» (2006). In Pratchett’s novels, Morris dance, which traditionally heralds the summer beginning, is balanced by a dance that marks the beginning of winter, indicating the natural cycles change. This manifests the functions of a sacred act: a dialogue between the world and a human, extracting the last from the flow of everyday life, and finalizing the routine work of a farmer. The study suggests the analysis of artistic means describing the Morris dance ritual as a marker of natural cycle changes and as evidence of a human establishing contact with natural forces, enshrined in the narrative and embodied in the dynamic form of dance. A common harvest festival turns into a Dance of the Death and a Maiden, which moves the process of harvesting and preserving the harvest into the realm of the sacred. The motive of the Death and a Maiden dance is being developed in the same compositional plane with the Morris dance motive, as an element of the narrative about the natural balance of life and death,fertility and harvest, about the cycle of the universe based on the love drive. The article examines the compositional elements of choreographic ekphrasis, highlights the significant elements of such a description, indicates the markers of the sacred and the profane, intrinsic to ritual dance in Pratchett’s novels. The conducted research allows to determine the role of dance in Pratchett’s literature work as a marker of the transition from one state to another, as well as season cycle changes.

Thermoreversible Gelation of Associating Polymers in Hydrogen-Bonding Mixed Solvents.

The thermoreversible gelation of associating polymers in hydogen-bonding mixed solvents is studied theoretically on the basis of the model ternary solution in which polymers carrying functional group A are dissolved in a primary solvent SB (mainly water) and cosolvent SC. Functional group A forms intermolecular cross-links (A-A) leading to gelation. It can also form hydrogen bonds with either solvent molecule SB or SC (A-SB, A-SC). If bound to a solvent molecule, A becomes inert. Solvent molecules form complexes with variable association numbers (SB-SC). Ternary phase diagrams for sol-gel transition lines and their cross sections on the temperature-solvent composition plane are constructed. It is shown that a minimum in the polymer concentration along the sol-gel transition line appears at a special solvent composition which depends upon the structure of the complexes. At such an optimal gel point, the sol-gel transition temperature becomes the highest, thus leading to stable, strong gels. The degree of adsorption, preferential adsorption coefficient, average molecular weight of the complexes, and cross-link probability are calculated as functions of the solvent composition. At the optimal gel point, the preferential adsorption coefficient changes its sign and the average molecular weight of the complexes reaches a maximum. Results are compared with the experimental data on poly(vinyl alcohol) in a mixed solvent of water/dimethyl sulfoxide, dimethyl sulfoxide/urea, or water/methanol.

Growth of SrB4O7 Crystal Fibers along the c-Axis by Micro-Pulling-Down Method

SrB4O7 (SBO) receives much attention as solid-state ultraviolet lasers for micro-machining, photochemical synthesis, and laser spectroscopy. For the application of SBO, the SBO crystals require the control of twinning to amplify the conversion light. We also expected that the inhibitation of the SrB2O4 appearance was essential. Here, we show the growth of SBO crystals along the c-axis through the micro-pulling-down method while alternating the application of electric fields (E). Without the application, single crystals were grown. At E ≧ 400 V/cm no needle domains of SrB2O4 inside SBO crystals existed; however, composition planes were formed and twin boundaries did not appear. In contrast, the inversion of surface morphology emerged, and the convex size was especially large at 1000 V/cm. These results demonstrate that convection is generated perpendicular to the growth front by alternating the application of electric fields. This surface morphological change contradicts the conventional concept of growth through the micro-pulling-down method. The distance from seed crystals vs. grain density plot also showed that the density did not decrease with a sufficient slope. Consequently, we concluded that the selection of the c-axis as growth faces is not fruitful to fabricate twins, and the selection of the growth condition, under which geometrical selection strongly affects, is the key.

ANALYSIS OF THE SHEAR LAG EFFECT IN WIDTH-VARIANT GIRDERS OF CABLE-STAYED BRIDGES

The research is based on a composite large-span double-tower single plane cable stayed bridge with the span of (54 m+108 m+340 m+108 m+54 m) in Zhejiang Ningbo Zhoushan port, the main girder of which faces the problem of a complex main girder with a large aspect ratio and remarkable shear lag effect. To study the shear lag effect of the cable-stayed bridge and the influence of the width-variant girder on the shear lag effect, we studied the main mechanical behavior and stress distribution of the main girder by combining the mixed finite element method and field measurement, and obtained the stress and shear lag coefficient distribution of the top and bottom slab in the finished state. The results show that the shear lag effect in the top and bottom slabs of the single-box triple-room cable stayed bridge is significant. With the increase of the width of the main girder in the widening section, the shear lag coefficient of the top slab decreases continuously. For the steel floor, the change of the number of U-ribs of the floor caused by the change of the width of the main beam leads to an uneven stress distribution of the bottom slab. Therefore, the arrangement of the longitudinal ribs of the floor can be optimized according to the distribution curve of the shear lag coefficient. The results are significant and provide useful reference for the design and construction of this kind of bridges.

MOSCOW METRO OF ALENA DERGILIOVA: IMAGE OF STABILITY AND FEATURES OF CHANGE

The article focuses on the study of graphic works depicting the life of the Moscow metro, created in 1980–1990 by the Moscow artist Alyona Dergiliova. The etchings convincingly reflect the life of our people on the threshold of national historical development. In her complex, variously sized, drawn from life compositions with many figures in motion, the artist mastered the whole range of compositional and visual devices that she would use in her narrative watercolours of the 2000s. She found the contrast of the pathos in the metro interior – stations with a bustling motley crowd of Muscovites deep in themselves and rather shabby travellers from the depths of the Russian backcountry – which became the counterpoint for her further creative search for the image of Moscow. Investigation of resources, experiments in methods of taking the motion of subjects beyond the boundaries of the compositional plane, allow the series to be included in the list of artistic experiments relentlessly carried out by Dergiliova despite the years of difficulties in her creative life. The theme of ‘A Man and His City’ is apparently simple but it is resolved in a multitude of complex relationships carried from life on the squares of Moscow over to the interiors of its underground. People above and underground are the same, with their acquired strangeness, yet their psychological state in a confined space is different. The environment – albeit imperceptibly – changes people. It is vibrant all the same, but in a different way. The architecture inside the metro is closer to the person, and Dergiliova successfully uses this aspect in building her composition. The compositions include many recognizable details of architectural decor which complement the central narrative. These details are clues helping the viewer to figure out its meaning. The characteristic feature of the metro is motion, and the artist draws numerous human figures, figurative stucco elements, sculptural compositions, chips and cracks in the steps, chandeliers swinging at the arrival of the subway train – into an endless cycle. Scenes depicting the entrances to the metro is a separate theme, which is almost non-existent in Russian art. By rendering the entrances as energy hubs – breaches between the aboveground Moscow and its underground – Dergiliova fills them with particular meaning, as all these people, drawn by a skilful and confident hand, will have to squeeze into the endless corridors and noisy subway wagons rattling on rails. Careful analysis of the artist’s creation reveals the disturbing condition of the master’s soul. The condition which the masters of art were firmly in for the entire decade after the events depicted in these works.

Assessment of the geometrically nonlinear behavior of thin cleavage type surface defects of anisotropic structure under shear

When designing up-to-date composite structure defects are allowable. In this case an important factor for design is in-service non-propagation of allowable defects. Thin surface defects of rectangular delamination type are examined in this paper. Defect structure is anisotropic and boundary conditions correspond to rigid support. Let us assume that tangential forces act in load-bearing composite panel plane. This investigation subject is thin surface rectangular defect. It is assumed that given shear forces act on the defect and its geometrically non-linear behavior is possible. For expert estimation of defect mode of deformation by Bubnov-Galerkin method analytical solution of non-linear problem is obtained. Expressions for rectangular panel membrane stress which appear in case of post-buckling behavior due to shear are explicitly given for mode of deformation estimation. In order to supplement practical significance of obtained analytical solution thin anisotropic panel design method based on post-buckling state with tangential forces is shown.

In-situ experiment on long-term behaviour of GFRP pipes under permanent bending

The present study aims at studying the long-term behaviour of composites (GFRP) subjected to permanent bending. The specificity of this study largely rests on the original conditions of in situ ageing of the specimens within an experimental structure of elastic gridshell, built in 2006 and disassembled in 2014. This prototype was made of rectilinear tubes which were elastically deformed into a 3D stable shape. The structural members constituted hence a unique set of relaxation tests in ambient conditions where a wide variety of curvatures were imposed by the 3D shape. After dismounting, the tubes were sorted according to their permanent curvature in the structure. They were then subjected to three kinds of tests: recovery, longitudinal bending and transverse bending tests. The results were then compared with those obtained during the construction of the prototype, before ageing, and with members aged under the same conditions but not mechanically loaded. The experimental results confirm the usual recommendations for using composites in civil engineering, which suggest limiting the flexural stresses to 30% of the tensile strength to avoid damage or creep problems. At the same time, they confirm the safety and long-term robustness of the concept of double curvature structures obtained by elastic deformation of a composite plane grid.

Simplicity in mean-field phase behavior of two-component miktoarm star copolymers.

Using self-consistent field theory, we systematically explore the microphase separation in the class of two-component miktoarm star copolymers containing a single conjunction point between different blocks by considering an extended list of candidate microphases. We plot mean-field phase diagrams in the plane of segregation strength and composition for an array of representative star copolymers. Three principal phase diagram topologies, dictated by different phase stabilities, are exposed, displaying a hierarchy in complexity by increasing the molecular asymmetry. Our investigation indicates that the phase diagram topology depends on the ratios of arm numbers and Kuhn segment lengths, which highlights the role of the coordination number ratio between different polymers at the domain interface. These findings reveal the simplicity of the general phase behavior and suggest a complete list of stable microphases for the entire class, which provide useful insight into studying copolymers with more complicated architectures and conformational properties.

Advanced computer model for analysis of reinforced concrete and composite structures at elevated temperatures

abstract: This paper is concerned on the development of a computational model based on finite element procedures for advanced analysis capable of estimating the behavior of reinforced concrete and composite steel-concrete plane structures exposed to fire. The program implemented is called NASEN, the specific thermo-structural module is used to analyze structures under fire conditions. The effects of geometric nonlinearity, material nonlinearity and nonlinear thermal gradients are incorporated into the model, as well as the degradation of material properties with increased temperature. The methodology applied for the solution is based on the unidirectional coupling of the thermal and mechanical solutions. The cross-sections of the structural elements are discretized with two-dimensional meshes for thermal analysis, while the structural analysis uses a one-dimensional beam-column element. Numerical examples are presented to demonstrate the accuracy of the computational code developed in relation to the numerical and experimental solutions found in the literature. In summary, the program adequately predicted the response of the studied structures.

Presence in Lume’s Work as Temporal Enlargement and Oceanic Feeling

ABSTRACT The article combines efforts to read Lume’s aesthetic based on possible philosophical connections supported by the notion of temporal enlargement and the Freudian concept of oceanic feeling. The philosophical-conceptual methodology was used to this end. The ideas of composition, fluctuation and saturation plane, delirium, the dissolution of borders and a sense of holistic connection stood out. Presence was the articulating element of Lume’s aesthetic, which is framed by the aforementioned conceptual principles. By exposing two possible receptions, the text intends the comparison with such knowledge to add layers of expansion to the theatrical aesthetic experience, not aiming to reveal meanings, but rather to propose intelligibilities.

Multiconductor Transmission Line Modeling of Crosstalk Between Cables in the Presence of Composite Ground Planes

Modern transportation systems, such as aircraft, are increasingly replacing metal body parts for composite materials, such as carbon-fiber reinforced plastics. Despite the multiple advantages in terms of weight, size, and fuel consumption, this trend is posing a challenge for protection of cables against electromagnetic interference. Early risk assessment and optimization of cable design in modern aircraft require reliable methods that can quickly and accurately estimate crosstalk behavior in the presence of lossy ground planes. This article presents two novel methods to incorporate such lossy ground planes into the crosstalk modeling of cable bundles. The first method considers the ground plane as a discrete collection of cylindrical conductors. In the second method a ground impedance matrix is derived for lossy ground planes with a finite thickness. Results of both methods are compared to full-wave simulations and measurements, yielding excellent results in terms of accuracy and computation times. The discretized ground plane method is also applied to the case of wire pairs that are enclosed by two ground planes, both aluminum and carbon–fiber reinforced plastic, as a first step towards investigation of wiring that is embedded in thermoplastic material. Once more simulations and measurements are in good agreement.

A Composite Magnitude-Phase Plane of Impedance Difference for Microgrid Protection Using Synchrophasor Measurements

This article presents a protection scheme based on the magnitude-phase plane of impedance difference (ID) using wide-area positive sequence components of current and voltage signals for the microgrid. The computation of the ID of the line is performed by extracting signals from the phasor measurement units complied with IEEE C37.118 standards. The composite magnitude-phase plane obtained from the magnitude of the ID and the angle of ID is considered as the key index for the detection of faults. The feasibility to include the proposed microgrid protection technique is examined by the extensive fault cases simulation with substantial variation in fault conditions, including types of fault and fault at different line length and for the grid-connected and islanding modes of microgrid operation. The fault study is carried out on a medium-voltage 15 bus test microgrid and a standard IEEE 34 bus microgrid testbed. The impact of several critical no-fault conditions is also investigated to analyze the possibility of false operation. The proposed ID-based scheme is extensively tested on MATLAB/Simulink platform and validated on the real-time digital simulator. The test results indicate that the magnitude-phase plane of the ID-based scheme can provide a dependable microgrid protection measure.

Chromium Members of the Pumpellyite Group: Shuiskite-(Cr), Ca2CrCr2[SiO4][Si2O6(OH)](OH)2O, a New Mineral, and Shuiskite-(Mg), a New Species Name for Shuiskite

A new pumpellyite-group mineral shuiskite-(Cr), ideally Ca2CrCr2[SiO4][Si2O6(OH)](OH)2O, was found at the Rudnaya mine, Glavnoe Saranovskoe deposit, Middle Urals, Russia. It occurs on the walls of 0.5 to 1 cm thick fractures in chromitite, filled with calcite, Cr-bearing clinochlore, and uvarovite. Shuiskite-(Cr) forms long prismatic to acicular crystals up to 0.1 × 0.5 × 7 mm elongated along [010] and slightly flattened on [100]. The crystals are commonly combined into radial, sheaf-like aggregates. Most observed crystals are simple twins with a (001) composition plane. Shuiskite-(Cr) is greenish-black under daylight or purplish-black under incandescent light. It is optically biaxial (–), α = 1.757(5), β = 1.788(6), γ = 1.794(6), 2V (meas.) = 45(10)°, 2V (calc.) = 46° (589 nm). The Dcalc is 3.432 g/cm3. The IR spectrum is reported. The chemical composition (wt.%) is CaO 21.33, MgO 3.17, Al2O3 5.41, Cr2O3 28.50, TiO2 0.18, SiO2 33.86, H2O 5.82, total 98.27. The empirical formula calculated based on the sum of eight metal cations and Si atoms per formula unit is Ca2.02Mg0.42Cr3+1.99Al0.56Ti0.01Si3.00O10.57(OH)3.43. The simplified formula is Ca2(Cr,Mg)(Cr,Al)2[SiO4][Si2O6(OH,O)](OH,O)(OH)2. Shuiskite-(Cr) is monoclinic, C2/m, a = 19.2436(6), b = 5.9999(2), c = 8.8316(3) Å, β = 97.833(3)°, V = 1010.17(6) Å3, and Z = 4. The crystal structure, solved from single-crystal X-ray diffraction data (R = 0.0469), is based on a pair of chains of edge-sharing Cr-centred octahedra running along the b axis, linked together via the [SiO4] and [Si2O6(OH)] groups and Ca-centred polyhedra. The mineral species shuiskite, ideally Ca2MgCr2[SiO4][Si2O6(OH)](OH)3, was renamed to shuiskite-(Mg) by the decision of the IMA CNMNC. The shuiskite solid solution series with the general formula Ca2XCr2[SiO4][Si2O6(OH,O)](OH)2(OH,O), which includes shuiskite-(Mg) and shuiskite-(Cr) with X = Mg and Cr3+, respectively, appeared in the pumpellyite group.

Optimization of the Interacting Stiffened Skins and Ribs Made of Composite Materials

A decomposition strategy for the structural optimization of a fiber-reinforced aircraft wing box is proposed. The proposed method decomposes the wing-box optimization into two levels: a system-level and a subsystem-level optimization. The ribs are the subsystems of the problem. Each rib has a local set of design variables and constraints. The loads on the ribs are the crushing loads caused by the bending of the wing. At the system level, the wing-box skins are optimized while accounting for the effect of the skin design on the loads applied to the ribs. The sensitivity of the rib mass to the applied loads is evaluated using the Lagrange multipliers of the optimized rib design. To enhance the numerical efficiency of the two-level optimization, the changes of the loads on the ribs are subjected to a reduction by principal component analysis (PCA). In both the wing-level and rib-level optimization problems, the level-set strategy for the optimization of composite structures, previously introduced by the authors, is employed. This method permits an advantageous use of coarse and fine finite element models employing a standard commercial finite element code. The proposed method is applied to the design of a composite horizontal tail plane. The accuracy of and the computational time savings by the proposed PCA-based reduction scheme are quantified.

Investigation of the large deformations of composite plane with interface crack loaded by uniform pressure

The analytical solution to a nonlinear problem of elasticity for the composite plane formed by connection of two half-planes from different materials with an interface crack is obtained. The elastic properties of half-planes are modeled by semi-linear harmonic material. External loading is uniform pressure, which is orthogonal to the deformed surfaces of a crack coasts, the stresses at infinity are absent. For the solution to a nonlinear plane problem methods of the theory of the complex variable functions are used. An existence of critical values of pressure at the coasts of a crack which excess conducts to loss of stability of a material and to large post-critical displacements, deformations and stresses in a vicinity of a crack is established. The critical pressures have the order of the shear modules of the materials and are really possible for low-modules rubber-like materials (elastomers). For the rigid materials with the large module of shear, in particular metals, the critical pressures really are not achieved. The formulas for disclosing of the crack coasts depending on value of pressure and parameters of materials are obtained, the plots of displacements of the crack surfaces for different values of pressure are presented. On the base of a common solution the asymptotic expansions are constructed for nominal (Piola) and Cauchy stresses in vicinities of a crack ends. The nominal stresses have the root singularities, the Cauchy stresses have no singularities at the tips of crack.

Распространение поверхностных волн в составной полуплоскости

Распространение поверхностных волн в составной полуплоскости

Investigation of Large Deformations of Composite Plane with Interface Crack Loaded by Uniform Pressure

Investigation of Large Deformations of Composite Plane with Interface Crack Loaded by Uniform Pressure

Assessment of Shear Stresses from Shrinkage and Thermal Deformation in Wood-Concrete Bridge Beams

AbstractThe aim of the paper is to assess the values of shear (delaminating) stress in the composition plane between the concrete (RC) deck slab and wood girder from concrete shrinkage, and shrinkage and swelling of wood, as well as difference in temperature between the wood web and concrete slab.

Study and Optimization of Oxygenated Apatite Obtained by Dissolution-Reprecipitation of Hydroxyapatite in a Solution of Hydrogen Peroxide

The experimental design strategy is applied to study and model the preparation of oxygenated apatite obtained by the dissolution-reprecipitation of hydroxyapatite in a hydrogen peroxide. The oxygenated apatite obtained is characterized by infrared spectroscopy (IR), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The characterization by analyzes (IR, DRX, SEM) shows that the dissolution-repricipitation method gives better results for oxygenated apatite containing molecular oxygen. For this, we studied the influence of the four factors such as the temperature of the reaction medium, the pH, the concentration of hydrogen peroxide and the mass of the attacked hydroxyapatite. As well as their interactions whose goal is to increase the molecular oxygen insertion rate in apatitic tunnel. The orthogonal centered composite plane allowed us to establish an equation that links the insertion rate according to the factors studied, and we obtained an optimum of introduction of 5.06%.