Different Types Of Deformation Research Articles

Why and How Does the Actual Spectral Response Matter for Microwave Radiance Assimilation?

AbstractBased on Global/Regional Assimilation and PrEdiction System‐Global Forecast System and actual Spectral Response Functions (SRFs) of three Selected Single‐Passband Channels (Channels 5–7) of FengYun‐3D MicroWave Temperature Sounders‐2, impacts of actual SRFs on Brightness Temperature (TB) simulation were analyzed. Compared with simulation by ideal SRFs, averaged STandard DeViation and bias of Observation minus Background by actual SRFs decrease about −5.0% and 37.3%. The reductions on Equatorial regions are more obvious than middle and high latitudes. Five types of deformations were put forward to analyze their impacts on TB simulation. Attenuation, shifting, and extending of passband have more impacts on simulated TB compared with trap on passband. The differences between TBs simulated using ideal and actual SRFs do not depend on the magnitude of the difference between ideal and actual SRFs, but on the balances of different types of deformations of actual SRF.

Evolution of temperature, humidity and deformation in early-age cement-based materials based on a multi-field model

Early-age cement-based materials undergo significant physical and chemical changes and have a complex mutual relationship among their temperature, humidity and mechanical behavior. As the second part of this study, this paper builds a multi-field coupling equation model taking into account the staged characteristics of the deformation for early-age cement-based materials based on the Hybrid Mixture Theory, and the accuracy of calculation results are verified with the test results obtained in the first part of this study. Moreover, the multi-field coupling model has been adopted to simulate the evolution of the different types of deformation for early-age cement-based materials. The results show that the multi-field coupling model established in this paper and the staged deformation calculation model established for early-age cement-based materials in the first part of this study can be used to better describe the development of their early-age temperature, humidity and deformation. Moreover, thermal strain is the earliest deformation that may cause cracking of cement-based materials, and chemical shrinkage has a certain compensation effect on thermal strain. In addition, the coefficient of thermal expansion (CTE) and the coefficient of stiffness influence (CSI) as well as their effects on thermal and chemical deformations have been analyzed. The results of this study can provide an important reference for analyzing the performance evolution of early-age cement-based materials.

Mapping and classifying large deformation from digital imagery: application to analogue models of lithosphere deformation

SUMMARY Particle image velocimetry (PIV), a method based on image cross-correlation, is widely used for obtaining velocity fields from time-series of images of deforming objects. Rather than instantaneous velocities, we are interested in reconstructing cumulative deformation, and use PIV-derived incremental displacements for this purpose. Our focus is on analogue models of tectonic processes, which can accumulate large deformation. Importantly, PIV provides incremental displacements during analogue model evolution in a spatial reference (Eulerian) frame, without the need for explicit markers in a model. We integrate the displacements in a material reference (Lagrangian) frame, such that displacements can be integrated to track the spatial accumulative deformation field as a function of time. To describe cumulative, finite deformation, various strain tensors have been developed, and we discuss what strain measure best describes large shape changes, as standard infinitesimal strain tensors no longer apply for large deformation. PIV or comparable techniques have become a common method to determine strain in analogue models. However, the qualitative interpretation of observed strain has remained problematic for complex settings. Hence, PIV-derived displacements have not been fully exploited before, as methods to qualitatively characterize cumulative, large strain have been lacking. Notably, in tectonic settings, different types of deformation—extension, shortening, strike-slip—can be superimposed. We demonstrate that when shape changes are described in terms of Hencky strains, a logarithmic strain measure, finite deformation can be qualitatively described based on the relative magnitude of the two principal Hencky strains. Thereby, our method introduces a physically meaningful classification of large 2-D strains. We show that our strain type classification method allows for accurate mapping of tectonic structures in analogue models of lithospheric deformation, and complements visual inspection of fault geometries. Our method can easily discern complex strike-slip shear zones, thrust faults and extensional structures and its evolution in time. Our newly developed software to compute deformation is freely available and can be used to post-process incremental displacements from PIV or similar autocorrelation methods.

Стратегия загрязнения пыльцы Artemisia и Chenopodiaceae

It is known that 30–40% of people in the world population are sensitized to pollen. This phenomenon is exacerbated in contaminated and urbanized areas. Wormwood is one of the main herbaceous allergenic plants, and its pollen is among the ten global aeroallergens. An allergy to it is a common phenomenon on a global scale. The role of pollen the etiology of pollinosis is usually in tandem with wormwood pollen established in Russia, Central Asia and Kazakhstan, Europe and America. The purpose of this article was to develop a pollen strategy for wormwood and pollen as the leading aeroallergen and assessment of their standardized contribution to the aerobiological situation. The SEM images of the studied pollen of wormwood do not show pronounced changes in the structure and sculpture, since it is tolerant to the effects of pollutants. Different types of deformation and modification of sculptural elements were revealed in pollen from the haze family, since their pollen selectively reacts to various pollutants. The strategy for pollen from wormwood and haze pollen is that, due to its strong, prickly exine, and lipophilicity, weed pollen is a very good biological accumulator of all types of gaseous or solid pollutants. In general, this accumulation depends on the physicochemical processes at the surface or cytoplasmic level, independent of the physiological state of pollen. Many biological agents, such as bacteria and fungal spores, can accumulate on the surface layer of the pollen shell and be used for bioindication.

Modeling a Thin Fiber Deformation and Destruction under a Dynamic Load

The problem of the propagation of deformations and stresses in a thin fiber under a dynamic mechanical load, as well as the destruction of the fiber, is considered. High-speed interactions in which the striker’s speed is comparable to the speed of sound in the fiber are considered. The numerical results are compared with an analytical solution for a point impact. Various loading modes are calculated for the distributed load on the fiber that cause significantly different types of deformations and destruction.

Limit states and safety factors under repeated loading

Verification of the structures operating possibility using numerical modeling beyond the elastic limit requires standardization of safety factors and calculation methods used to get them. In the framework of the discussion on the improvement of the strength standards of the aviation and nuclear industries for structures operating under low-cycle mechanical and reversible dilatation (temperature, hydrogen) external influences, the article discusses the limiting states; the deformation properties of materials necessary for their calculation; safety factors for loads and durability; calculation methods. The article divides limit states of structures under low-cycle actions into two groups: typical, corresponding to a qualitative change in the deformation type, and individual, determined by allowable displacements and cracks for a particular structure. The following types of deformation are considered: inelastic deformation only at the running-in stage (that changes to elastic after the auspicious residual stresses develop and cyclic hardening of the material); alternating flow (that continues with the number of cycles); progressive accumulation of strains and displacements; combined deformation (when both strain span and strain increment are non-zero in a stable cycle). The types of deformation differ in possible consequences for the structure and the initial data for the calculation: mechanical properties of the material required for modeling different types of deformation should be determined by fundamentally different tests. An analysis of individual limit states without taking into account differences in the types of deformation - and thus typical limit states - may be incorrect. The main focus of the article is on typical limit states. The limit states vary depending on the stage of operation at which inelastic cyclic deformation is allowed. Inelastic deformation expands allowable load range, the expansion due to the inelastic deformation at the running-in stage only is usually more significant than additional expansion due to the continuous inelastic deformation; besides, the inelastic deformation only at the running-in stage does not demand analysis of low-cycle fatigue and accumulated strains. Further expansion of the permissible load range, as well as solution of safety problems based on risk assessments, requires a more complete study of the deformation properties of materials at the pre-fracture stage, where cyclic softening predominates.

INTERACTIVE SHAPE MODELING USING FUNCTIONALLYDEFINED OBJECTS

Creating digital models is a complex task in computer graphics. Animation developers usually use two methods. The models are either sculpted from a traditional material such as clay or plasticine, and then the model must be digitized. Models can alsobe created using one of several commercial (or custom) modeling systems, such as MAYA or SoftImage. Since clay can be molded to create smooth surfaces and precise details, most designers very often use this method. It would be useful to give users the same opportunity as modeling from clay or plasticine, but in virtual space. So that the designer can deform the work piece, add details, and remove unnecessary parts. In addition, virtual shopping malls, virtual worlds, scientific visualization, design, construction, and so on,require huge costs to transmit three-dimensional geometric data over the network. This requires a compact description of three-dimensional objects.Considering these requirements, methods were developed with the following features. Innovations in the interactive modeling interface that take advantage of functional model assignment. This is the orientation and positioning of the sculpting tool relative to the surface.The paper describes the interactive modeling of deformation forms of models based on perturbation functions. Such objects are characterized by a high degree of smoothness and are described by a small number of functions. They are easyto deform and create shapes similar to modeling from plasticine. The proposed method of deformation of the functionally based models with fast visualization allows to provide the interactivity and a realistic appearance of the resulting shapes. An interactive modeling of deformations is presented.The process of interactive modeling of geometric shapes defined by perturbation functions is described. A method for interactive modeling of functionally defined objects without preliminary triangulation is proposed. This allows more accurate definition of3D shapes and simplifies the modeling system. The algorithm for finding the minimum common parent for the objects, the algorithm for adding an object (perturbation) to the scene, and the algorithm for selecting the objects in the scene were developed for this purpose. A method for visual representation of free forms and analytical perturbations for interactive modeling is developed. An interactive scene editor has been created with the ability to save the result both as a scene file and as a bitmap image. The set of primitives for constructing scenes has also been expanded, and the properties of new primitives have been investigated. When creating the editor, work was done to optimize the rasterization algorithm. A method adapted for graphic processing units is used for rapid rendering of 3D models. The considered scientific problem can be used to facilitate the modeling of 3-dimensional surfaces with different types of deformations, which can be relevant for solving applied problems.

Classification of soft-sediment deformation in carbonates based on the Lower Cretaceous Vigla Formation, Kastos, Greece

Soft-sediment deformation (SSD) structures are widespread within the Lower Cretaceous Vigla Formation (limestones and shales) that are exposed in a 7–10 km long and 100 m high section along the east coast of Kastos Island in the Ionian Sea. SSD was observed both in limestones and in shales, and formed during or immediately after deposition, during the first stage of sediment consolidation. They are classified into six (6) different types of deformations: (1) Thick synclines and anticlines, formed due to strong synsedimentary deformation, that were produced mostly from N-S directed normal faults or from the interaction between normal and transfer faults, and are situated between undeformed horizons. (2) Thin slumps ascribed to normal fault activity and especially slumping in the footwall of the active fault, prograding orthogonal to the fault direction. (3) Thin to medium slumps produced from the synsedimentary interaction of N–S normal faults and E–W directed transfer faults, showing multiply directions of progradation. (4) Thin SSD related to diapiric intrusions that also associated with fault activity. (5) Thick slump horizons displaying erosional contacts with the neighboring undeformed limestones in the same horizon, resulting from gravity-driven mass-transport deposits that flowed across inclined basin floors. (6) Thin slumps, with chert nodules, within a slumped horizon, resulting from a slumping phase both after the sedimentation and after early diagenesis in carbonates deposits, but during the sedimentation of the lower Cretaceous Vigla limestones. All the above categories were characterized as seismites or deformation due to fault activity. This tectonism resulting in tilted blocks, the creation of space in hangingwall downthrown blocks, and changes of inclination of the basin floor, outcrops with high lateral extent in different directions adds constraints to the geometry of slumps. The transition zone between Vigla limestones and shales showed particularly abundant deformation structures. Although the Vigla Formation limestones have low primary porosity, the presence of many SSD horizons could increase secondary porosity in this formation.

Characterization and numerical simulation of laminated glass fiber–polyester composites for a prosthetic running blade

The objective of this work was to explore different types of deformations (buckling, bending, and relaxation) on the properties of laminated composites based on polyester as the matrix and glass fiber in two forms: woven and chopped strand mat. The specimens were produced with the same thickness but with different number of ply. Also, a thin gelcoat based on clay particles was applied on the chopped strand mat samples to get a third series. The results showed that using the same thickness, the mechanical properties, especially in terms of bending and buckling, are influenced by the layers’ number. Furthermore, a sports application, which is the main objective of this work, is presented as an applied investigation for a leg prosthesis. Three different running blades “Flex-foot Cheetah” were manufactured to be experimentally and numerically (ANSYS ACP software) characterized to simulate real conditions. The results showed a good agreement between the experimental and numerical values in terms of total displacement, which is around 50 mm, the produced blade has been tested in quasi-static and dynamic compression, and results showed that the relaxation behavior depends on the structure design and the used materials.

DEFORMATIONS IN THE MIDDLE AMERICA TRENCH ACCORDING TO EARTHQUAKE FOCAL MECHANISMS AND THEIR FEATURES IN THE AREA OF THE 2017 МW 8.2 CHIAPAS EARTHQUAKE, MEXICO

Seismotectonic deformations in the Middle America Trench and their features in the area of preparation of the Chiapas earthquake, М W =8.2, 08 September 2017, were determined using the data on 2244 focal mechanisms of earthquakes for the period of 1977–2017. The distribution of seismicity with depth was studied in detail. The decrease in the depth of the Benioff zone in the north-western subduction segments and the increase in the south-eastern segments is associated with the age of the subducting parts of the Cocos plate and the angle of their immersion. The latter mechanism can also explain the presence of earthquakes with normal focal mechanism on the oceanic uplift in the south-eastern segments of the subduction zone and their absence in the north-western ones. In general, the typical character of subduction deformations has a number of features in the Middle America Trench. The predominance of shortening by horizontal components and elongation by vertical ones at depths up to 35 km is replaced by the transitional type with mosaic distribution of deformations of different signs in the depth range of 36–70 km. Even lower, in the depth range of 70–105 km, the type of deformation changes to the opposite with respect to the upper horizon. The Chiapas earthquake occurred on the border of regions with different types of deformation, which indicates softening of the block’s medium to the west of the hypocenter and its hardening to the east. Such a state of the lithospheric medium may indicate the presence of a deformation shadow zone in the Chiapas earthquake preparation area.

Forearc Basin Stratigraphy Resulting From Syntectonic Sedimentation During Accretionary Wedge Growth: Insights From Sandbox Analog Experiments

AbstractForearc basin stratigraphy is expected to record a detailed history of the deformation and growth pattern of an accretionary wedge. However, the relationship between syntectonic basin sedimentation and growth of a wedge remains poorly understood, including how deformation of the wedge modifies the basin stratigraphy and how syntectonic sedimentation influences deformation of the wedge. This study reproduced accretionary wedges with and without syntectonic sedimentation by analog sandbox experiments. The results show that basin stratigraphy varied with changes of the growth pattern of the accretionary wedge. In the case that wedge growth was dominated by frontal accretion phase, the depositional area migrated trenchward. In contrast, underthrusting phase caused the sediment layers to be tilted landward and the depocenter to migrate landward. A prolonged underthrusting can result in combining a retrowedge basin with a wedge top basin and yield a wide area of accommodation space. The occurrence of two types of basin stratigraphy (trenchward and landward migration of the depocenter) reflects the two different types of deformation (frontal accretion phase and underthrusting phase), and these differences possibly depend on a contrast in strength of the basal shear resistance between the inner and outer parts of the wedge due to temporal and spatial variations of sedimentation on the wedge. A change in the magnitude of normal stress acting on the wedge base likely influenced the mode of deformation of the wedge. These results suggest that forearc basin stratigraphy is influenced by the growth pattern of accretionary wedges, which is itself affected by syntectonic sedimentation.

АНАЛІЗ ПАРАМЕТРІВ АКУСТИЧНОЇ АНІЗОТРОПІЇ ПІРОКСЕН-МАГНЕТИТОВИХ ПОРІД ПІЩАНСЬКОЇ СТРУКТУРИ

The analysis of the results of acoustic properties of rocks study of Pischans`ka iron-ore structure is presented. The aim of the work is to establish the features of the distribution of acoustic properties and parameters of acoustic anisotropy in samples of core rocks selected from the well No. 3 of the Pischans`ka structure to determine the nature of its occurrence. A sample of 35 samples from the depth range 144-273 m is divided into 3 groups of rocks, namely: magnetite-pyroxene, quartz-magnetitepyroxene and biotite-amphibole crystalline shales. Based on an invariant polarization method, a number of acoustic laboratory measurements have been carried out. The values of the measured phase velocities "quasi-longitudinal" and two "quasi-transverse" waves at the stage of measurements showed significant acoustic anisotropy of the rocks. The ranges of the measured speeds of the collection samples are 7661 ÷ 5046 m / s for longitudinal waves and 4232 ÷ 2648 m/s for transverse ones. The difference in values measured for each of the sides of the cubic rhombic dodecahedron is from 100 to 800 m / s and from 0 to 500 m/s for Vp and Vs, respectively. The parameters of an acoustic ellipsoid were calculated, on the basis of which the division of samples into 3 main groups has been performed, according to the acoustic texture: acoustically linear, shale and rhombic. Separately, a group of samples with a more complex texture was discovered. The analysis of coefficients of anisotropy by different methods is carried out: longitudinal, transverse and relative acoustic anisotropy. Most of the samples are characterized by low or average acoustic anisotropy (from 2 to 7 %). A group of highly anisotropic rocks (11–14 %), represented by samples of biotite-amphibole crystalline silicates, is singled out. According to the parameters of the acoustic tensor of most samples, the transverse isotropic type of symmetry inherent to samples from the depth intervals 174–220 m and 222–232 m, while the smaller part is rhombic, is inherent. Differences in the parameters of anisotropy of samples can be explained by the significant heterogeneity of their textures, namely: micro cracks, minerals of various sizes, shapes and orientations. The results of the research show that the acoustic properties of the samples are quite heterogeneously distributed along the investigated depth range. This indicates the difficult conditions for the formation of rocks at different depths and the presence of different types of deformations, which accompanied the formation of the Pischans`ka structure.

Deep Local Feature Descriptor Learning with Dual Hard Batch Construction.

Local feature descriptor learning aims to represent distinctive images or patches with the same local features, where their representation is invariant under different types of deformation. Recent studies have demonstrated that descriptor learning based on Convolutional Neural Network (CNN) is able to improve the matching performance significantly. However, they tend to ignore the importance of sample selection during the training process, leading to unstable quality of descriptors and learning efficiency. In this paper, a dual hard batch construction method is proposed to sample the hard matching and non-matching examples for training, improving the performance of the descriptor learning on different tasks. To construct the dual hard training batches, the matching examples with the minimum similarity are selected as the hard positive pairs. For each positive pair, the most similar non-matching example is then sampled from the generated hard positive pairs in the same batch as the corresponding negative. By sampling the hard positive pairs and the corresponding hard negatives, the hard batches are produced to force the CNN model to learn the descriptors with more efforts. In addition, based on the above dual hard batch construction, an ℓ22 triplet loss function is built for optimizing the training model. Specifically, we analyze the superiority of the ℓ22 loss function when dealing with hard examples, and also demonstrate it in the experiments. With the benefits of the proposed sampling strategy and the ℓ22 triplet loss function, our method achieves better performance compared to state-of-the-art on the reference benchmarks for different matching tasks.

A new type of slumping-induced soft-sediment deformation structure: the envelope structure

Abstract The sediments of the Cretaceous Gyeokpori Formation in south-western South Korea accumulated in a lake in which mainly siliciclastic rocks were deposited, with some interbedded volcaniclastics. The nearby volcanic activity resulted in unstable lake margins inducing a dominance of gravity-flow deposits. The high sedimentation rate facilitated soft-sediment deformation on the sloping margin. The deposition of numerous gravity-flow deposits resulted in a vertically heterolithic stratification. The slumps are composed of different lithologies, which is expressed in different types of deformation due to the difference in cohesion between sandy and mussy layers within the slumps. Coarser-grained (cohesionless) slumps tend to show more chaotic deformation of their lamination or layering. The difference in slumping behaviour of the cohesive and non-cohesive examples is explained and modelled. A unique soft-sediment deformation structure is recognized. This structure has not been described before, and we call it ‘envelope structure’. It consists of a conglomerate mass that has become entirely embedded in fine-grained sediment because slope failure took place and the fine-grained material slumped down with the conglomerate ‘at its back’. The cohesive laminated mudstone formed locally slump folds that embedded the non-cohesive overlying conglomerate unit, possibly partly due to the bulldozing effect of the latter. This structure presumably can develop when the density contrast with the underlying and overlying deposits is exceptionally high. The envelope structure should be regarded as a special – and rare – type of a slumping-induced deformation structure.

When, what and how image transformation techniques should be used to reduce error in Particle Image Velocimetry data?

Particle Image Velocimetry is commonly used to compute velocity fields in several areas including fluid mechanics, hydraulics and geophysics. However, acquired images often contain deformations caused either by camera lenses or placement. In this work the most popular digital transformation methods used to remove/reduce these deformations are benchmarked and suggestions tailoring specific transformations to different types of deformations are made. This article also shows the reduction of the error associated to the first and second order statistics, in the case of two-dimensional Particle Image Velocimetry, when the transformation techniques are applied to the computed velocity fields, and not the raw images, a common option in available commercial software.

Structural State Effect on Mechanical Properties and Acoustic Emission of High-Purity Titanium at Different Types of Deformation

The results on investigations of mechanical properties of high-purity titanium with grains ranging from tens of nanometers up to a few micrometers subjected to uniaxial tension, compression and microindenting are presented. Different structural states in high-purity titanium were formed by severe plastic deformation according to the scheme «upsetting – extrusion – drawing» in combination with annealing at temperatures of 250–550° C and quasi-hydrostatic extrusion at room and liquid nitrogen temperatures. The values of yield strengths and microhardness for samples of high-purity titanium with grains of different sizes are determined. It was shown that the combination of severe plastic deformation with cryogenic quasi-hydrostatic extrusion allowed to create high-purity nanocrystalline titanium with high mechanical properties. The obtained experimental data were analyzed for the implementation of the Hall-Petch relation and discrepancy between the values of yield strengths in tension and compression (strength differential or S-D effect). Satisfactory fulfillment of the Hall-Petch relation for high-purity titanium in the whole range of the studied grain size values was shown and a noticeable difference in the yield values for compression and tension was found. The values of the coefficients in the Hall-Petch equation for deformation by tension, compression and microindenting were determined. These coefficients are noticeably lower than the corresponding values for the industrial grades of titanium, i.e. in high-purity titanium, the grain boundaries are weaker barriers for moving dislocations than in the industrial titanium, whose boundaries are enriched with impurities. The features of the acoustic waves emission during compression of samples in various structural states were studied. It was concluded that the deformation of titanium in all the investigated structural states was carried out by dislocation slip.

Effects of tectonic stress environment on tectonophysical features of deformed coal

ABSTRACTTo study the effects of the tectonic stress environment on the tectonophysical features of deformed coal, No.8 Mine in the Pingdingshan mine area is used as a study area and the relationship between the development of deformed coal, distribution of fractures, formation of deformed coal and tectonic stress environment are analyzed. The results indicate that the thickness of the bedrock layer should be included in the analysis of the tectonic stress environment for a region of intense tectonic activity. Although the reverse faulting stress regime can control the development of deformed coal, the C seam is extremely sensitive to the stress regime. The most advantageous direction of the deformed coal fractures is consistent with the regional maximum principal stress, and the development of fractures is closely related to the evolution of the tectonic stress environment. The fracture density of the E seam presents a uniform distribution, yet that of the C seam is completely heterogeneous. Superposition and compounding of the tectonic communities evidently increase the fracture density of the deformed coal. There is a relatively apparent boundary between the different types of deformation, which gradually transform from brittle to ductile with a decreasing lateral pressure coefficient. A generalized deformation pattern of the deformed coal is proposed and can be divided into frictional sliding and solid flow.

Studies of the ice regime in the waters of the Gulf of Khatanga in the Laptev Sea

The study was carried out to reveal characteristics of the ice regime of poorly explored water area of the Khatanga Bay in the South-Western part of the Laptev Sea. Actuality of the research is due to the high potential of hydrocarbon reserves in the license area «Khatangsky» of the PAO «NK «Rosneft Currently available methods of monitoring ice cover and hydrometeorological conditions throughout the year were used. The main features of the hydrological regime of the region in the ice-free period, reflected in the spatial distribution of thermohaline characteristics and sea level fluctuations, are shown. The area under investigation has specific features of the conditions for the formation of ice cover: the entire area is covered with the fast ice; the winter fresh water infl w from Khatanga and Anabar rivers results in the desalination of sea water, and this promotes formation of ice cover, which differs in crystal structure and texture from both fresh and sea ices. These factors do influence on the mechanical properties of ice, including its strength. It was found that the average and maximum values of strength of the smooth and deformed ice of the Khatanga Gulf are approximately twice as high as the similar values of the sea ice strength in the southern part of the Laptev Sea. The basic features of the spatial distribution of different types of deformations of the ice cover such as lines of ice hummocks, zones of homogeneous ice hummocking, and stamukhas had been determined.

A Destruction Model for an Anisogrid Composite Structure

Finite element modeling of the deformation and fracture processes in a composite anisogrid (network) structure made of carbon fiber reinforced plastic (CFRP) with different types of deformation has been performed. The anisogrid structure is based on a longitudinal set of ribs supported by diagonal sets of ribs directed at angles of about ±45° with respect to the longitudinal ribs. Based on the model of mechanical property degradation for composite material layers strength analysis of the structure has been performed taking into account the process of damage accumulation in the course of loading. The maximum destructive load is determined and the fracture pattern is obtained for each type of deformation. The determining impact of the rib-crossing zones of different directions as the foci of progressive destruction of the entire anisogrid structure is established.

Influence of Uniaxial Deformation on Surface Morphology and Corrosion Performance of Trivalent Chromium Based Coatings for Packaging Steels

The packaging steel industry has many products for the consumer market which are deformed to a required shape. Products produced in this way undergo different types of deformation, including uniaxial, biaxial and plane strain. In a situation where the steel is coated and then deformed, the coating must still offer a substantial level of protection for inhibiting corrosion. An In Situ scanning kelvin probe (SKP) experiment was used to investigate the kinetics of organic coating disbondment on uniaxially deformed trivalent chromium coated steel. The studied material was a model trivalent chromium coated steel prototype, designed for over coatings with a lacquer or polymer laminate. The samples were uniaxially deformed to 5%, 10%, 20%, 25% strain using a Hounsfield/Tinius Olsen tensile tester prior to any further experimentation. The strain percentages selected corresponded to the yield point elongation zone, strain-hardening zone and early and late necking zones respectably. A model Poly(vinyl) butyral (PVB) coating was applied to the uniaxially deformed samples. A defect was created in the PVB coating and the sample exposed to aqueous sodium chloride electrolyte in 95% relative humidity. The disbondment kinetics of the polymer overcoat were measured every hour using the SKP, for up to 120 hours. The disbondment kinetics have been quantified as a plot of distance (µm) vs time (tdel− ti), see Figure 1. The linear plots suggest as the strain percentage is increased the distance of delamination over a 24 hour period increases. Scanning electron microscope (SEM) images, shown in Figure 2, display cracking of the trivalent chromium coating. The availability of the underlying iron is estimated by studying the surface controlled hydrogen evolution curves. Increasing the uniaxial strain produced higher values for hydrogen evolution. It is proposed that the increase in hydrogen evolution levels can be related to an increase in the exposure of iron caused by the cracking formations found on the surface. The cracking shown on the surface of the trivalent chromium coated steel (Figure 2) is also suggested to cause the increase in cathodic disbondment rates found during the SKP investigations. Cracking of the surface and exposure of iron is suggested to allow for a continuous cathodic front, causing an ingress of electrolyte underneath the PVB model coating. This investigation displays a link between surface cracking, caused by deformation, and the delamination rates of organic coatings on trivalent chromium coated steels. Figure 1