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Purpose To present a surgical technique and case presentation of internal chandelier-assisted macular buckling for myopic foveoschisis. Methods Review of patient clinical features, visual-acuity and optical coherence tomography (OCT) results following internal chandelier-assisted macular buckling for myopic foveoschisis. Results A 48-year-old highly myopic female (axial length 29.85mm) underwent internal chandelier-assisted macular buckling for myopic foveoschisis with macular detachment. The best-corrected visual acuity improved from 20/150 to 20/40. Post-operative OCT confirmed central buckle positioning and demonstrated resolved foveoschisis and macular detachment. There were no complications. Conclusions Internal chandelier-assisted macular buckling is a valuable tool to optimize buckle position and patient outcomes.

Continuous Welded Rail (CWR) forms a smooth high-speed rail track. However, its stability has been a cause of worry for being a slender structural element and its tendency to buckle about the weaker axis. Track-Bridge Interaction (TBI) phenomenon results in additional axial rail stress, creating local high-stress zones in the track. Since TBI is the main reason for rail stress and track displacements of CWR on railway bridges, more confidence needs to be developed by quantifying the stability of CWR-on-bridge. In this study, a simplified numerical model is proposed to study the effect of TBI on the stability of CWR-on-bridge due to temperature loading. Boundary elements are utilized to reduce the number of elements in the model. The model predicts the state of the stress in CWR due to thermal loading. Stability analysis of CWR on a single span bridge employing nonlinear buckling analysis reveals a significant influence of TBI on CWR stability. The two critical buckling parameters of CWR, the maximum buckling temperature ( T max ) and safe temperature increase ( T min ), are affected by TBI. T min drops more rapidly compared to T max and needs to be kept below the safe limits to ensure track safety.

Purpose To evaluate the outcomes and complications of scleral buckle surgery alone or combined with pneumatic retinopexy (pneumatic buckle) for the treatment of primary rhegmatogenous retinal detachment. Design Retrospective chart review. Participants Two hundred thirteen patients with rhegmatogenous retinal detachment of whom 101 underwent primary scleral buckle surgery at Rabin Medical Center in 2005–2015 (SB group) and 112 underwent pneumatic buckle surgery at Royal Alexandra Hospital in 2013–2015 (PB group). Methods All patients were followed for ≥12 months. Data on clinical and surgical parameters, outcome, and complications were collected from the medical files. Main Outcome Measures Best corrected visual acuity and anatomical outcomes. Results At 12 months, average best corrected visual acuity was 0.3 logMar in the SB group and 0.42 logMar in the PB group ( P Conclusion Scleral buckle surgery alone is efficient for the treatment of rhegmatogenous retinal detachment. Its combination with pneumatic retinopexy usually has no significant added value in terms of anatomical reattachment rate. Outcomes of Pneumatic buckling vs Scleral Buckling for RRD

This paper studies rings with rigid segments and rotationally flexible joints under compressive forces. Using geometry and symmetry, exact closed-form expressions for the buckling forces are found. Depending on how the forces are applied, the ring may not buckle at all, or may buckle with a regular pitchfork bifurcation, or may have nonlinear snap-through and hysteresis characteristics. The latter defines a global buckling load below which the ring is stable under any finite disturbances. The buckling properties of the square and hexagonal rings are important since they serve as unit cells for larger structures such as honeycomb, graphene and tensegrity structures.

In this paper, the behavior of initially imperfect reinforced concrete columns with different eccentricity and end restraint conditions at elevated temperatures is studied. By constructing column curves for the heated columns, the combined and interrelated effects of initial imperfection patterns, rotational end restraint level, self-equilibrating thermal stresses, and end eccentricity condition for columns with different slenderness ratios are investigated. The study shows that for each column curve, there exists a characteristic fire resistance that is a maximum and not affected by end restraint characteristic. It was found that for all columns, there is a critical value of slenderness ratio after which column responses to fire change. It was also found that under certain conditions, an antisymmetrically loaded column with an initial out-of-straightness experiences a double-phase unwinding phenomenon and may fail in a single-curvature buckling mode, but they cannot buckle in an antisymmetrical double-curvature mode. This is quite different from symmetrically loaded columns with initial out-of-straightness of opposite sense of gravest buckling mode, which show a single-unwinding phenomenon and can fail in either a single- or a double-curvature buckling mode. The investigation revealed that the values of effective length factor at high temperatures are different from those at ambient temperature, and these values are slightly affected by the end eccentricity, column slenderness, and load ratio.

120 years ago, on June 22 (June 9 old style), 1901 the Committee on construction of the Trans-Siberian Railway approved final decision on the location of the route of Circum-Baikal Railway (CBR).This railway is a monument to the heroic construction of the Trans-Siberian Railway. At the beginning of 20th century, the whole world followed its construction: someone with a shudder, someone with curiosity. The main goal was defined by the urgent need to connect the Central part of Russia and the Far East. Hence, there was an insurmountable natural obstacle on the way: the largest lake in the world. Today the CBR is an architectural reserve, englobing a huge number of engineering structures. Many of them are still unique. Prospecting work on Lake Baikal lasted for 13 years. The lake is surrounded by mountains, 300 tributaries from different rivers flow into it. So laying a railway track was an extremely difficult task, Russian engineers have brilliantly coped with.

It is more than two decades now since the earliest state-endorsed appropriations of mostly white-owned commercial farms in Zimbabwe. The Third Chimurenga – or Fast-Track Land Reform Programme, as t...

Slender fibrous assembled structures can easily buckle under longitudinal compressive load. The limitation in characterizing the longitudinal compression behavior poses a significant challenge to the mechanics optimization of such structures. To address this challenge, we use one-dimensional yarns as a model system, and the yarns are deformed in bending to form a strain gradient, from tension to compression, along the radial direction of the yarns. The compression modulus as a function of compression strain is calculated based on bi-moduli elastic theory. The evolution of the fiber arrangement and the position of the neutral layer in the yarn is interpreted along with the change of compression modulus. Also, the local stress distribution in the bent yarn was determined by finite element simulation, and it is remarked that the bending property of yarns is sensitive to the compression modulus. The present study offers insights on the modeling and simulation of fabrics and garments in drape and bending deformation. Results from such investigations can provide effective guidance for the mechanical and structural design of textiles and textile-based composites.

Modern electronic devices are usually subjected to thermo-mechanical loads and prone to buckle during their operation. Thermo-mechanical stability is a crucial standard for their reliable applications. This paper explores the size effect on the thermo-mechanical behavior of the organic solar cells. An effective isogeometric analysis method combined with modified couple stress theory is presented. The thermo-mechanical buckling load-bearing capacities of the organic solar cells subjected to various in-plane loadings, temperatures, and geometrical parameters are discussed. Numerical results show that the size effect has significant effect on the thermo-mechanical load-bearing capacity. The stability region changes minimally when the material length scale parameter $$l$$ to cell thickness $$h$$ ratio is less than 0.2, while the stability region increases remarkably when it is larger than 0.2. Notably, if the material length scale parameter increases to its thickness, the stability region increased almost 25 times than that without size effect. Furthermore, the stability region is narrowest if the temperature is uniform across the thickness direction of the cell.

The use of cold-formed steel (CFS) channels with circular or rectangular web holes is becoming increasingly popular in building structures. However, such holes can result in sections becoming more susceptible to buckle and display lower load-carrying capacities. This paper presents a total of 42 axial compression tests of CFS lipped channel slender columns with and without circular and rectangular web holes, including different hole sizes and cross sections. The test results show that the axial members with a small ratio of width to thickness were governed by global buckling, while the members with a large ratio of width to thickness were controlled by the interaction of local, distortional, and global buckling. The axial strength decreased maximum by 20.48% and 22.98% for the member with circular holes and rectangular holes, compared to a member without a web hole. Then, a nonlinear elastoplastic finite element model (FEM) was developed, and the analysis results showed good agreement with the test results. The validated FE model was used to conduct a parametric study involving 36 FEMs to investigate the effects of column slenderness, dimension of the hole, and the number of holes on the axial strength of such channels. Furthermore, the formulas to predict the global buckling coefficient and the effective area were modified for such sections with holes by using the verified FEM. Finally, the tests and parametric study results were compared against the design strengths calculated in accordance with the developed method. The comparison results show that the proposed design method closely predicts the axial capacity of CFS channels with circular or rectangular web holes.

In Liquid Composite Molding (LCM), a fabric can be formed by highly double curved punch geometries. During the forming step, various types of defects can appear and may have a significant influence on the mechanical properties of the final composite materials. Till now, these defects have not been fully studied and/or understood. The aim of this study was to understand the mechanisms leading to the forming of mesoscopic defects (buckles and sliding), as well as their effect on the behavior of composite materials. To achieve this goal, an experimental machine was designed and built. The machine generates different types of defects, with controlled and adjusted amplitudes (calibrated defects) in samples of a fabric. These samples were then used to manufacture composite samples with calibrated defects, by an LCM process, in order to test and compare them with composite samples without defects. Thanks to this machine, calibrated forming defects that simulate the defects of an LCM process were generated, and the experimental parameters corresponding to the appearance of these defects were defined for two types of fabrics based on glass and carbon fibers. This work provides insight into the forming mechanisms of the buckle and sliding defects that occur during an LCM process.

The potential for spontaneous failure of quarry pit floors by various buckling modes has increasingly become a concern because of the potential impacts on safety, the environment, and mining operations. The most notable and concerning form of buckling failure is referred to as a “pop up” which is a nearly-instantaneous and violent event similar to a rock burst. A means to evaluate potential risk from this hazard within a rational engineering framework is required to aid with licensing and operations decisions. A first step in understanding the likelihood of buckling event occurrence under various conditions is the review of a thorough compilation of past observed in situ events. The objective of this study is the development of a database of observed cases to provide insight into the various buckling failure modes and associated geotechnical conditions. Although available documented historic case study details vary significantly, the collected data, as a whole, is of value. All available, information on the geological environment, rock type, mechanical properties, in situ stresses, and buckle dimensions are documented within the database. The database has been analyzed and revealed trends relating buckling orientation and in situ stress orientation/magnitude. In addition, the database has been used to develop a categorization of the main buckling-related failure modes which is presented along with a summary of their associated typical analysis methods.

The cylindrical shell having a diameter to thickness ratio more than 10 is normally called as thin cylindrical shell. The primary threat to the thin cylindrical shell is axial compressive force. This force leads to buckling and it provokes the failure of shell. Owing to several consequences in terms of loss of injury, property, life & damage of failure incidents, pipeline planners are setting more accentuation both on protection measures against outside impedance and on giving sufficient obstruction against buckling. The universally useful FE code ANSYS is utilized for the improvement of the material disappointment model. A numerical alignment technique is portrayed which empowers the utilization of standard pliable test information for steels and measure of weight as the contribution to the trial arrangement with and without internal pressure. Current work describes the buckling analysis of thin shells and their consequences that arise as a result of geometric imperfections. For experimental purpose beverage can has been selected, and are subjected to manual loading conditions by placing the cans between two discs, and buckling load is determined. Experimental buckling was also calculated for the beverage cans with square and round cutouts and their corresponding deflections have been tabulated. The experimental results are compared with numerical results to identify the deflection, and also confirmation of limit conditions used. The load at which the thin cylindrical shell starts to buckle, yield point and maximum failure load will be determined by the results.

PURPOSE To describe and evaluate the application of a new 3-D printing-assisted personalized macular buckle for patients with myopic foveoschisis (MFS). METHODS Twelve eyes of 12 patients with MFS were included in this study. Preoperative MRI images were subsequently measured after marker implantation and imported into the MIMICS software for the 3-D reconstruction of a virtual model of an eyeball and a marker. The virtual eyeball model was designed according to the degree of retinoschisis, which was measured using optical coherence tomography preoperatively. A macular buckle was designed using a titanium stent, assisted by 3-D printing; furthermore, it was surgically placed in combination with pars plana vitrectomy. Visual acuity, axial length and anatomic outcomes were analysed pre- and postoperatively. RESULTS Macular schisis in all patients was completely resolved after the surgery without any postoperative complications. The mean postoperative best corrected visual acuity (LogMAR) improved significantly from 1.21 to 0.92 during the 6-month follow-up period (p

Purpose To investigate the indications for scleral buckle removal and the risk factors for the recurrence of rhegmatogenous retinal detachment after scleral buckle removal. Methods In this retrospective study, the medical records of all patients who underwent scleral buckle removal for the treatment of rhegmatogenous retinal detachment were reviewed. Results Forty eyes (40 patients) were included in this study. The indications for scleral buckle removal included exposure without infection in 23 eyes (57.5%), exposure with infection in seven eyes (17.5%), elevated intraocular pressure in six eyes (15.0%), strabismus or diplopia in three eyes (7.5%), and migration of buckle material in one eye (2.5%). After the removal of the scleral buckle, the recurrence of rhegmatogenous retinal detachment was observed in four eyes (10.0%) during follow-up, and the retina was successfully reattached after pars plana vitrectomy in all the eyes. Most clinical and ocular factors of the eyes with and without the recurrence of retinal detachment during follow-up were not different, but the eyes that underwent encircling removal were more likely to have retinal detachment recurrence during follow-up than those that underwent segmental buckle removal (n = 4 / 16 [25.0%] vs. n = 0 / 24 [0.0%]; p = 0.020). Conclusions Scleral buckle removal can result in the recurrence of retinal detachment. The benefits and risks of scleral buckle removal should be carefully considered before surgery, and extensive monitoring during follow-up after scleral buckle removal is important, especially for patients who underwent encircling removal.

The hydrophobicity of film surfaces can be enhanced by introducing wrinkling and buckling, and the wrinkling method in this study is a facile way to induce various microstructures including wrinkles and buckles in film surfaces. When buckles formed, the water contact angle parallel to the wrinkled direction (θ//) changed dramatically with strain, but the contact angle perpendicular to the wrinkled direction did not change much. It was found that the buckle structural feature was the key characteristics affecting the change in contact angle, θ//. A dimensionless number, the ratio of buckle height to spacing (Hb/Sb) was introduced to determine the relationship between the structural feature and the contact angle, θ//. The contact angle, θ// strongly depended on Hb/Sb. The thickest film (hf = 605 nm) at the highest strain (ɛ = 30%) and the highest Hb/Sb formed many large buckles, and exhibited super-hydrophobicity (θ// = 169 ± 10°).

Lord Martin Rees is the 15th Astronomer Royal, a position established by England’s King Charles II in 1675. He has served at the highest levels of science and is one of the world’s most recognized ...

The propensity of shear deformable beam members obeying to the Timoshenko beam theory to buckle under axial tension is contested in the paper. For Timoshenko beams under uniform tension, the existing theories supporting this statement extend the findings of Haringx, derived for the compressive case only, to tensile axial forces by considering that the negative root of the quadratic equation arising from the eigenboundary problem related to the stability analysis for compression is itself a critical load, tensile due to its negative sign. Notwithstanding, a tensioned beam is not the mirror case of a compressed one and the appropriate mathematical procedures are applied consistently, in the present paper, to analyse the stability behaviour of Timoshenko beam members under uniform tension. Bearing in mind that a critical state is a mathematical concept that models the physical behaviour of a structural frame under specific circumstances, it is found that no buckling occurs if the mathematical tools are applied correctly, and the mentioned tensile buckling load is not a buckling load, because it does not render null the determinant of the eigenboundary problem that represents the stability problem of columns, neither for tension nor for compression. Therefore, the application in the engineering practice of all theories stating that Timoshenko beams are prone to tensile buckling, in addition to the compressive one, shall be precluded until new and irrefutable proofs come to light. The paper ends with the analysis of a structural system that really buckles when tensioned. It was developed in the literature that lays behind us and consists of two rigid rods connected by a transverse slider. Within this context, a correspondence is established between this latter system and an alternative one, whose propensity to buckling arises from overlapping bars that are compressed as the frame as a whole is being tensioned. By doing this, a connection is established between tensile buckling due to shear singularities and the tensile buckling of Ziegler, which is due to overlapping.

Background and Purpose: The impact of the coronavirus disease 2019 (COVID-19) pandemic on stroke systems has not been systematically evaluated. Our study aims to investigate trends in telestroke consults during the pandemic. Methods: We did retrospective chart review of consecutive patients seen through a telestroke network in South Carolina from March 2019 to April 2020. We dichotomized patients to preCOVID-19 pandemic (March 2019 to February 2020) and during COVID-19 pandemic (March to April 2020). Results: A total of 5852 patients were evaluated during the study period, 613 (10.5%) were seen during the pandemic. The median number of weekly consults dropped from 112 to 77 during the pandemic, P =0.002. There was no difference in baseline features; however, Black patients were less likely to present with strokes during the pandemic (13.9% versus 29%, P ≤0.002). Conclusions: The COVID-19 pandemic has led to a significant drop in telestroke volume. The impact seems to disproportionately affect Black patients.

Performance evaluation and design of civil facilities against earthquakes is a challenge to engineers because of the large uncertainty in the seismic demand and capacity of structures. The purpose of the study is to perform comparative analytical investigation of performance-based behavior between Moment Resisting Frames with Structural shear Walls, Concentric Braced Frames & Buckle Resisting Braced Frames of a concrete structure by using ETABS-2017 software. The comparative analytical evaluation of the study will be based on the parameters such as displacement, inter-story drift, pushover curve and life expectancy level. The purpose of the study is to obtain a structural system which is more efficient, reliable and strong in its nature and strength.

The Zimbabwean writers Catherine Buckle and Nyaradzo Mtizira reimagine kongonya dance in their works Beyond Tears: Zimbabwe's Tragedy (2002) and The Chimurenga Protocol (2008), respectively. Both the European-born Buckle and the black Zimbabwean Mtizira harness the dance to evoke the post-2000 jambanja experiences associated with Zimbabwe's controversial “Third Chimurenga,” or the fast-track land reform program, beginning in 2000. Their contrasting depictions of dance epitomize the differing views on Zimbabwe's land reform program. Largely, whereas Buckle's novel is a memoir which personalizes a farmer's encounters with dancing African/Zimbabwean “land invaders,” Mtizira's is a panegyric that collectively reimagines a nation's defiant revolution against purported forces of Western imperialism. Both writers’ representations of the post-2000 Zimbabwe's dance performances are therefore colored and compromised by racial subjectivity.

In structural engineering, buckling is usually associated with compressive stress and/or shortening deformation states. Recently, several works came to light alerting to the propensity of some structural systems to buckle under tension. Within this context, the present work examines the buckling and post-buckling behaviours of repetitive rods systems under tensile axial loading, and comprises three distinct parts. At first, the tensile stability behaviour of a single rigid rod with an edge section supported by a slider that is forced to follow a pre-established path, developed in the literature that lays behind us, is revisited and related to the buckling behaviour of an alternative two rods system whose buckling propensity arises from a secondary compressed bar overlapping the tensioned one. In the second part of the paper, overlapping is used to create innovative repetitive frames that buckle under tension, in the present case a sequence of lined up rigid rods connected by rotational joints. The tensile critical load shows little change as new modules are added to the system, in clear contrast with the compressive case. The tensile post-buckling behaviour is also assessed, in some cases showing original shapes, and overlapping is used to create repetitive frames with negative thermal expansion coefficient as well. In the third part of the paper, the effects of applying global gradients to the relevant mechanical properties, in the form of smooth variations of the joints rigidities and rods lengths as the module is repeated, on the stability behaviour under tension are assessed. Although these variations are smooth and kept within small values, they provoke significant changes on the tensile buckling load, on the buckling type and on the type of buckling as well. The findings pave the way to the development of innovative repetitive frames, cellular materials, polymer chains and origami structures showing original constitutive behaviours under tension.

Modeling and robotic handling of a plastic box buckle is discussed in this paper. The closing mechanism of the box buckle is simulated to determine the characteristic of the nonlinear load-deflection curve. An intelligent end-effector was designed and manufactured to handle the assembly with a robot. The closing force is measured by a built-in load cell and its values are processed by a micro-controller. The intelligent end-effector can be used in a robotic system, which deals with different snap-fit applications.

A compressively stressed poly (dimethylsiloxane) (PDMS) film with a sputtered gold film can buckle owing to the difference between the Young’s modulus of the PDMS film and that of the gold film. Th...

A cache of Roman copper-alloy fragments was discovered, apparently carefully layered in a pit, in a field in Gloucestershire by metal-detectorists in 2017. The assemblage comprises over 5 kg of metal pieces, predominantly box fittings, but also smaller items of personal use such as a fourth-century belt buckle, a three-strand bracelet, a spoon and a coin (a nummus of Crispus). Most remarkable are the sculptural fragments, including several pieces of life-size statuary and the complete statuette of a dog with fine incised decoration, and part of an incised bronze inscription panel. This article considers the original form of the statuary and the use and deposition of the cache. It is proposed that these fragments represent the remains of the accoutrements of a temple or shrine in the local area, perhaps dedicated to Diana Venatrix, and that they were removed and deposited together in the late fourth century. Supplementary material is available online (https://doi.org/10.1017/S0068113X20000501) and comprises additional figures.

The scraper is the core of the conveyor and its vulnerable part. The problem of bending fracture of common welding scrapers in actual production is under consideration. SolidWorks and ANSYS finite element analysis software were used to construct the three-dimensional model for simulation analysis, and the existing structure was improved and optimized. The comparison results showed: well-type stiffener contributes to improvement of the overall strength and rigidity of the scraper. Before optimization, the maximum equivalent stress on the press buckle part of the scraper was 310 MPa, and after optimization it dropped to 230 MPa, i.e., decreased by 26%, and the stress value of one side of stiffener was 170 MPa, with certain bending resistance. After optimization, the stress distribution of the scraper was uniform, with solving the problem of stress concentration. After optimization, the overall safety factor of the scraper increased by nearly 15%, improving its life. Integrity of the optimized scraper was nearly 100%, as compared to that before optimization under the same conditions, which confirmed the validity of scraper optimization.

According to the buckle release theories, the seat belt can be released during an impact and the occupant sustained injuries without a benefit from the restraint system. A few studies have been published demonstrating that the seat belt release during an impact results in belt entanglement of occupant’s outboard arm. However, there is no previous belt entanglement study using airbag equipped vehicle. Two controlled sled tests in 30-degree oblique frontal impact using airbag equipped vehicle were conducted at 44 km/h delta V to compare the driver occupant kinematics, physical evidence on seat belt system and occupant interaction with the seat belt in fully restrained and partially restrained condition. The fully restrained test demonstrated the nature and extent of the physical evidence placed on a latched and properly worn restraint system. Loading marks were found on restraint’s webbing and hardware including the latch plate and guide loop (D ring). The partially restrained test results showed that a release of the latch plate was followed by webbing engagement with the ATD left arm and subsequent loading. This loading event produces large contact forces on the left arm which can produce significant surface injuries.

RESUMO: Este trabalho teve como objetivo simular computacionalmente o comportamento estrutural de pilares de aço submetidos à compressão axial e avaliar a influência das imperfeições geométricas e de materiais (tensões residuais) sobre a capacidade resistente destes elementos. Para isso, desenvolveu-se, com auxílio do software Abaqus, modelos computacionais de elementos finitos que foram analisados em duas etapas, a primeira correspondente a uma análise de flambagem elástica (Buckle) e a segunda a uma análise não-linear plástica (Static Ricks). Os resultados obtidos pelos modelos desenvolvidos foram comparados com os resultados apresentados pela equação de flambagem elástica proposta por Euler e pela curva de flambagem prescrita pela ABNT NBR 8800:2008. De forma geral, os resultados computacionais se aproximaram dos valores de referência, o que indica que os modelos computacionais conseguiram simular o comportamento estrutural de um pilar real e que a metodologia proposta é válida. Ao analisar a influência das imperfeições geométricas observou-se que os modelos com imperfeições de L/1000 e L/1500 foram os que mais se aproximaram dos valores de referência. No caso das imperfeições de materiais, os modelos com 10% e 15% de tensões residuais foram os que mais se aproximaram. Desta forma, as estratégias adotadas podem contribuir para futuras pesquisas relacionadas à flambagem de pilares de aço submetidos à compressão axial. ABSTRACT: This research aimed to simulate the structural behavior of steel columns subjected to axial compression and to evaluate the influence of geometric and material imperfections (residual stresses) on the strength of these elements. In order to achieve this aim, finite element computational models were developed using Abaqus, which were analyzed in two stages: an elastic buckling analysis (Buckle) and a nonlinear plastic analysis (Static Ricks). The results obtained were compared with the results presented by the elastic buckling equation proposed by Euler and the buckling curve prescribed by ABNT NBR 8800: 2008. In general, the results obtained were very close if compared to the reference values. It indicates that the computational models were able to simulate the structural behavior of a real pillar and that the proposed methodology is valid. When analyzing the influence of the geometric imperfections, it was observed that the models with imperfections of L/1000 and L/1500 were the ones that most approached the expected results. In the case of material imperfections, the models with 10% and 15% of residual stresses were the ones that presented the best results. In this way, the adopted strategies may contribute to future research related to the structural behavior of columns and buckling.

Spontaneous formation of various buckle-delamination patterns originates from complex interaction between buckles and delamination. However the impact of large compression and delamination boundary undulation on the morphology of buckle-delamination remains a challenge especially from an analytical approach. Here, a nonlinear solution based on the Foppl–von Karman (FvK) plate theory for buckle-delamination is derived by using a coordinate transformation technique in combination with perturbation series based on Koiter expansion. The analytical results validated by finite element simulations (FEM) show that the sequential sectional profile of straight-sided (SS) blister with asymmetric secondary buckling instability exhibits a butterfly shape dependent on the compression amplitude even when the delamination boundary is straight. Besides, the wavelength for SS blister after the instability drastically changes with the compression amplitude, which is coincident with the experimental results. Our analysis further demonstrates that the elastic energy of the wavy-sided blister can be significantly lower than that of the SS blister even when the initial equi-biaxial compression is a little larger than the Euler buckling stress, significantly lower than the critical stress for secondary buckling instability of SS blisters. This result indicates an alternative mechanism that formation of telephone-cord blister may proceed first by an undulation instability of the delamination boundary.

Background Ingrowing Nail is an ailment in the toe area. This problem is observed in 20% of the population, in all age groups, but most often occurs in teenagers and young adults. The process of ingrowing nail stimulates natural defense mechanisms of the body in the form of inflammation and severe pain. Aims The aim of this paper was to make the VHO-Osthold® Perfect buckle effective as an alternative to nail plate surgery and to determine the patient's comfort during this method of treatment. Patients/methods A descriptive case study conducted in a 15-year-old patient who had ingrowing nails in the big toes of both feet. Results It has been shown that the VHO-Osthold® Perfect buckle therapy constitutes an effective method for ingrowing nails and one in a few conservative methods in orthonyxia, as an alternative to surgery. Conclusions The study and clinical experience confirm that the therapy of ingrowing nails with the VHO-Osthold® Perfect buckle is painless and noninvasive. This treatment can be safely and effectively carried out by a qualified podiatrist or cosmetologist in podological practice.

This article introduces a Pazyryk kurgan, unearthed at Khankarinsky Dol, in the northwestern Altai. On the basis of the funerary rite, burial goods, and radiocarbon analysis, the kurgan dates to the late 6th or early 5 th centuries BC and is one of the earliest Pazyryk kurgans in this area known to date. A detailed description of artifacts is provided, including a bimetallic dagger, bronze hairpins, a quiver hook, a mirror, a belt buckle, a slotted clip, a knife, and a torc lined with foil. Special attention is paid to the details of a horse harness, which include bronze bits, two bone plaques, cheek-pieces, four strap distributors, a shackle, two clasps, and a bone girth buckle. The analysis of zoomorphic images on cheek-pieces suggests that the images of a wolf and a short-snouted feline carnivore are interchangeable in Scythian-Saka art. Evidently, the distinction between them mattered less for the nomads than did the fact that the animal was a carnivore. The reconstruction of the early Pazyryk horse harness is proposed. The burial rite and the burial goods indicate a high social status of those buried.

Global buckling of slender walls, reported only in a few laboratory tests before 2010, became a critical issue in design of reinforced concrete buildings after it was observed following the 2010 Mw 8.8 Chile earthquake and the 2011 Mw 6.3 New Zealand earthquake. Researchers have proposed theoretical buckling models based on prismatic columns subjected to uniform tension/compression cycles, where the key parameters are slenderness ratio, number of curtains of reinforcement, and maximum tensile strain before buckling during load reversal. These models have shown sufficient accuracy in comparison with laboratory tests on columns under such loading conditions. However, buckling in walls is more complex because of variation of strains through the wall depth and variation of moment along the wall height. Nonlinear finite elements are used to evaluate the effects of these more complex loadings on buckling of wall boundary elements. Analyses showed that the maximum tensile strain (averaged over the wall out-of-plane unsupported height) required to buckle the wall during load reversal does not depend on the moment variation along the wall height. Moreover, for typical wall lengths, the wall boundary behaves like an isolated column subjected to axial force cycles, with minimal apparent bracing provided by the wall web. This allows to analyze a broad range of practical cases for buckling susceptibility using simplified approaches based on buckling models of axially loaded columns.

An effective way of protecting offshore lines that carry corrosive hydrocarbons, is by mechanically lining carbon steel pipes with a thin layer of corrosion resistant alloy. A disadvantage of this product, is that when bent to curvatures such as those experienced during reeling the liner can buckle. The sensitivity of this instability to the main problem parameters was previously studied under pure bending. In the present study the problem is examined under the more complex loading experienced as it is wound onto a reel while under some back tension. A large-scale custom numerical model of the winding process of a previously expanded lined pipe is presented capable of dealing with the geometric, material and contact nonlinearities of the problem. The model is used to establish the deformation history experienced by the carrier and liner pipes during winding, the causes of liner instability, and its sensitivity to the main problem parameters. During reeling, a transition length a few diameters long bends to an increasingly larger curvature until it comes into contact with the reel. Back tension controls the length and curvature of this transition zone safeguarding the line against local buckling. Modest levels of tension are shown to also delay the onset of liner wrinkling. The more complex loading history experienced by the lined pipe as it approaches the reel changes the prevalent buckling mode but its sensitivity to initial geometric imperfections reported under pure bending remains. The liner instability becomes more prevalent as the diameter increases but at the same time smaller diameter lines could be reelable. The recent trend of winding lined pipes under small levels of internal pressure is confirmed to be an effective means of avoiding liner instability.

The MIRAgel (hydrogel) scleral buckle, introduced in the 1980s, was a novel material to repair retinal detachments. It was later discontinued due to the frequency of long-term complications related to buckle hydrolysis and expansion. These complications included pain, limited extraocular motility, and more serious complications such as infection or scleral perforation, which ultimately necessitated surgical extraction as late as 20–30 years after placement. Prompt and proper diagnosis and treatment is often delayed as these buckle-associated complications frequently mimic other orbital pathologies such as tumors or infections. The hydrolyzed MIRAgel buckle exhibits distinct radiographic features that are helpful in arriving at the correct diagnosis, particularly in cases of ambiguous clinical presentation or history. Here, we expand on the previously described radiographic features of hydrolyzed MIRAgel and compare them to features of common, mimicking orbital pathology.

International audience; The buckling of a gold thin film deposited on a rigid substrate has been numerically investigated by means of static molecular dynamics simulations. Three different regimes of deformation have been identified depending on the values of the adhesion energy of the film on its substrate (Gamma(int)). For low adhesion energy, the buckling and gliding through dislocation emission into the interface have been observed. For intermediate values of Gamma(int), the dissociation of the interfacial dislocations into the film leads to the formation of a Lomer-Cottrell lock that stops the buckle extension, promoting thus the propagation of a crack accompanied by the emission of dislocations. It results in the formation of a twin. For large values of Gamma(int,) the kinking of the interfacial crack has been evidenced along with dislocation nucleation at its tip leading to twins again. Finally, the different evolutions of the film have been summarized in a "behavior" diagram displayed in the plane of applied strain and adhesion energy variables. (C) 2019 Elsevier Ltd. All rights reserved.

The paper is devoted to belt buckles of the early Sarmatian period of the Turgay steppes. Turgay deflection is a vast territory located in the north-western part of Kazakhstan. In the north, Turgay deflection turns into the west Siberian lowland, and in the south it turns into the Turan lowland. In the west, the bend touches the Trans-Ural plateau, while in the east - the Kazakh hills. Three buckles originating from burial № 5A of mound 1 of the Karatomar burial ground and mound 1 of the Kenysh 3 mound group are analyzed. The paper deals with the cultural and chronological position of Turgay belt buckles in the context of the distribution of such products of the belt headset on the territory of Eurasia. The problem of the origin and chronology of these items is also touched upon. Buckles similar to the Karatomar one have so far been found only on the territory from Central Asia and Kazakhstan to the Lower Volga region. Kenysh buckle finds an analogy from the Volga-Don interfluves to the north of China. In General, types of buckles, similar to Turgay, existed in the II-I centuries BC. The studied buckles should be considered in the context of the general fashion for wearing a belt headset made of metal, bone and stone, associated with the military activity of the Huns.

In this work, we investigate a novel testing method for fatigue testing of a thin sheet under fully reversed conditions. Specifically, the fatigue behavior of thin-plate AA6082-T6 was characterized by laminating multiple thin gage specimens together to form a thicker specimen to prevent buckling under low-cycle fatigue testing. In this unique technique, ASTM E606 fatigue specimens were bonded together with a structural adhesive in double and triple laminates, and fatigue behavior was compared against monolithic control specimens. To quantify the fatigue behavior of the laminated AA6082, strain-controlled experiments were conducted, where the fatigue life experimental results exhibited comparable fatigue performance to the published literature. Postmortem analysis of the laminated AA6082 revealed a similar fatigue nucleation and crack growth damage mechanisms compared to the monolithic fatigue specimens. Lastly, a microstructure-sensitive fatigue life model was utilized to elucidate structure–property fatigue mechanism relations of the monolithic, double-, and triple-laminate specimens. The fatigue behavior of laminated specimens exhibits good correlation to wrought AA6082-T6 mechanical properties and thus suggests that laminating sheets together can be used to quantify fully reversed fatigue behavior of thin sheets that would otherwise buckle under compression loading.

Introduction: Pathological myopia is commonly associated with myopic traction maculopathy, which includes foveoschisis, foveal retinal detachment, macular hole (MH) and/or macular detachment (MD). Macular buckling is a rarely practiced extraocular surgical modality these days. The purpose of this study was to investigate the efficacy of primary buckling with Morin–Devin T implant for MD with MH and posterior staphyloma. Case description: A 52-year-old female presented with light perception vision in her right eye with posterior staphyloma, localized neurosensory detachment, and MH. She underwent primary macular buckling with Morin–Devin T implant. During the immediate postoperative day the wedge indentation was found misaligned to the fovea. A revision surgery was done after 2 weeks for repositioning of the macular wedge. Spectral domain optical coherence tomography confirmed indentation at the MH with resolution of subretinal fluid and hole closure. Her BCVA was 2/60 at 3 months postoperative and it remained the same even at 6 months of follow-up. Conclusions: Primary macular buckling can be an effective procedure in eyes with MH with detachment and posterior staphyloma with or without associated foveoschisis. Morin–Devin T implant placement is a relatively simple procedure with short surgical time and excellent outcome.

Solvent evaporation in unpinned droplets of colloidal suspensions leads to the formation of porous shells which buckle under the pressure differential imposed by drying. We investigate the role of aspect ratio of rod-shaped particles in suppressing such buckling instabilities. Longer, thinner rods pack into permeable shells with consequently lower Darcy's pressure and thus avoid buckling.

This article presents the results of study of an Early Bronze ivory figurine from Tourist-2, using 3D-scanning with various technical parameters. The aim of the study was to test the new non-invasive methods of structured light 3D-scanning, with an accurate assessment of morphometric characteristics. In addition, use-wear analysis was employed to evaluate the previously unknown features relating to function. As a result, the original appearance of the figurine, the manufacturing technique, and iconographic characteristics were reconstructed. A series of transverse sections and the evaluation of the center of mass, combined with previously known features, suggest that the figurine was a personal ornament sewn onto clothing. For comparison, two flat anthropomorphic sculptures (a buckle made of burl, and a shale figurine) from the same burial complex were analyzed. Longitudinal sections suggest that, despite morphological and technological differences and the fact that various raw materials had been used, the iconographic style of all items is one and the same.

Offshore pipelines used for transportation of hydrocarbons in the oil industry are subjected to external pressure, internal pressure to ensure flow, temperature and axial compression which causes buckling. Finite element modeling was performed, and experiments were conducted on pipeline models made of stainless steel of grade SS304. Present research work focuses on the improvement in buckling strength of offshore pipelines stiffened with rectangular pin buckle arrestor along the length of a pipeline using finite element analysis and their experimental validation. The results of finite element analysis showed that an offshore pipeline model without buckle arrestors has a buckling load of 4.69 kN whereas offshore pipeline stiffened with buckle arrestors of length 1000 mm along the length of a pipeline resulted in maximum buckling load of 14.075 kN. Accordingly, pipeline models were fabricated for conducting experiments. Comparison of finite element analysis results and experimental outcomes showed that the efficiency of buckle arrestor increased significantly by incorporating buckle arrestor along the length of a pipeline.

Present research work focuses on improving buckling strength of offshore pipelines by strengthening them with inclined stiffeners and inclined stiffeners with connecting rods. Eigenvalue buckling analysis was carried out using Finite Element Methods to find the buckling strength of the considered pipeline models. Seamless stainless steel pipe models of SS304 grade were considered for finite element analysis. The pipeline models were provided with inclined stiffeners whose angle of inclination varies from 100° to 176°. Connecting rods of different lengths is used to improve capacity of inclined stiffeners. In this paper, the effect of inclined stiffener configurations in improving the strength of offshore pipelines against buckling is presented. The finite element analysis results show that a pipeline strengthened with inclined stiffeners and inclined stiffeners with connecting rod showed improved buckling load carrying capacity.

Offshore pipelines are subjected to various forces, depending on the subsea conditions such as temperature, axial forces, pressure (internal and external), bending, and earthquake forces. The response of offshore pipelines in with-standing these forces involves elastic response as well as inelastic response. Buckle arrestors are installed at regular intervals along the length of the pipeline to prevent buckling occurring due to a combination of forces. Present research work focuses on the improvement in buckling strength of offshore pipelines which are stiffened with 3 different types of buckle arrestors. Buckling experiments were conducted on pipeline models fabricated from seamless stainless steel pipes of grade SS304. The pipeline models stiffened with three different buckle arrestors configurations; longitudinal continuous stiffener, sinusoidal stiffener, and angular stiffener. The purpose of our research is to study the effectiveness of buckle arrestor configuration in improving resistance to buckling and to identify optimum buckle arrestor configurations and their applicability to offshore pipelines. The study was conducted by finite element simulation of buckle arrestors using ANSYS. The stainless steel pipe models of 1 m length, 16 mm outer diameter, 11.8 mm inner diameter, 2.1 mm thickness are considered for finite element analysis and for conducting experiments. The results obtained from finite element analysis and experiment results show that the efficiency of buckle arrestor found to be more in case of pipeline stiffened with longitudinal continuous buckle arrestors.

A series of physical tests and finite element (FE) analyses are conducted to evaluate the failure of smooth (conventional) and textured (proposed concept) pipes. To do so, hydrostatic pressure tests are performed on aluminum beverage cans (ductile failure) and additively manufactured Ti6Al4V-0406 titanium pipes (brittle failure). Mechanical material properties are obtained from tensile tests of coupon samples. In the absence of physical burst pressure tests, FE models are validated against experimental results of external pressure tests and are used to predict the buckle initiation (Pi) and burst pressure (Pb) capacity of the textured pipes with different number of circumferential triangles, N, and base angles, α. Results show that buckle initiation pressures of the textured concept is 2.34 and 1.80 times greater than those of the smooth aluminum cans and titanium pipes, respectively. However, the burst pressure of the textured pipe can only get 3% greater than the smooth pipe. Based on the current results, a textured pipe with N = 6 and α = 30 deg is the optimum textured design.

The conventional buckling type of brace members offers lateral stiffness to the structural system; however, such members are likely to yield under tension and buckle under compression when ...

The buckle before the lens coating is still typically disassembled manually. The difference between the buckle and the background is small, while that between the buckles is large. This mechanical disassembly can also damage the lens. Therefore, it is important to estimate pose with high accuracy. This paper proposes a buckle pose estimation method based on a generative adversarial network. An edge extraction model is designed based on a segmentation network as the generator. Spatial attention is added to the discriminator to help it better distinguish between generated and real graphs. The generator thus generates delicate external contours and center edge lines with help from the discriminator. The external rectangle and the least square methods are used to determine the center position and deflection angle of the buckle, respectively. The center point and angle accuracies of the test datasets are 99.5% and 99.3%, respectively. The pixel error of the center point distance and the absolute error of the angle to the horizontal line are within 7.36 pixels and 1.98°, respectively. This method achieves the highest center point and angle accuracies compared to Hed, RCF, DexiNed, and PidiNet. It can meet practical requirements and boost the production efficiency of lens coatings.

Buckle propagation of local collapse appearing in the damaged pipes is one of the failure modes that are of particular interest for deepwater application. The local collapse can propagate along the pipeline for long distances in both directions when the external pressure magnitude is up to the propagation pressure. In this paper, the buckle propagation pressure of sandwich pipes (SP) with different material properties and geometric characteristics is investigated by numerical simulation using Python programming language based on general finite element code. The results of the pressure history data obtained are verified by comparing those published previously. The effect of material properties, geometric characteristics and adhesion conditions on the propagation pressure are analyzed.

Price transparency purports to help patients make high-value health care decisions, however, there is little data to support this. The pediatric distal radius buckle fracture (DRBF) has 2 equally efficacious but not equally priced treatment options (cast and splint), serving as an excellent potential model for studying price transparency. This study uses the DRBF model to assess the impact of up-front cost information on a family's treatment decisions when presented with clinically equivalent treatment options for a low-risk injury.Participants age 4 to 14 presenting with an acute DRBF to a hospital-based pediatric orthopaedic clinic were recruited for this randomized controlled trial. Participants were randomized into cost-informed or cost-blind cohorts. All families received standardized information about the injury and treatment options. Cost-informed families received additional cost information. Both groups were allowed to freely choose a treatment. Families were surveyed regarding their decision factors. Cost-blinded families were subsequently presented with the cost information and could change their decision. Independent samples t tests and χ2 tests were utilized to evaluate differences.A total of 127 patients were enrolled (53% cost-informed, 47% cost-blind). The 2 groups did not significantly differ in demographics. Immobilization selection did not differ between groups, with 48% of the cost-informed families selecting the more expensive option (casting), compared with 47% of the cost-blind families. Cost was the least influential factor in the decision-making process according to participant survey, influencing only 9% of families. Only one family changed their decision after receiving cost information, from a splint to a cast.Families appear to be cost-insensitive when making medical treatment decisions for low-risk injuries for their child. Price transparency alone may not help families arrive at a decision to pursue high-value treatment in low-risk orthopaedic injuries.Level I.