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Buckling is typically the governing failure mode of thin‐walled shells. In particular, geometric and material imperfections have a major influence on the buckling behavior. Small variations of imperfections have large effects on the load‐bearing behavior. However, the design of shells is still characterized by a deterministic way of thinking, in which uncertainties have not yet been sufficiently considered. Even in probabilistic approaches, false assumptions are often generated due to the small amount of experimental data. The focus of this paper is an appropriate uncertainty quantification based on the available data. Therefore, the concept of polymorphic uncertainty modeling is presented on axially loaded shells with different types of imperfections. Finally, an idea for a novel design concept for shells based on a fuzzy‐valued safety level is introduced. The paper is intended to initiate a rethinking of the methodology for the numerical design of shells with an appropriate uncertainty quantification. [ABSTRACT FROM AUTHOR]

The local stability of unsymmetric laminated structures is significantly affected by bending‐extension coupling and the comparatively low transverse shear stiffnesses, which have to be included in the structural analysis. If such structures have flat surfaces in segments, they can be investigated with the discrete plate analysis. In this analysis, the individual segments are considered as plates with rotational restraints that represent the supporting effect of the surrounding structure. The aim of this work is to improve the analytical stability of laminated plates. Therefore, Lévy‐type solutions for the buckling load of the mentioned laminated plates are considered and refined. This offers exact solutions for unsymmetrical cross‐ply laminates as well as antisymmetric angle‐ply laminates. In order to show the influence of shear deformations, the solutions for classical laminated plate theory (CLPT), first‐order shear deformation theory (FSDT), and third‐order shear deformation theory (TSDT) are worked out and compared to each other. In the context of TSDT, a new formulation for the rotational elastic restraint is presented, which affects the rotation and the warping of the plate cross‐section. This investigation presents the influence of shear deformations on different laminates and classifies the benefits of the different laminated plate theories with respect to the stability behaviour under different boundary conditions. In addition, the influence of bending‐extension coupling on different fibre angles and layer sequences is analysed. [ABSTRACT FROM AUTHOR]

The current study presents an experimental investigation devoted to the nano‐silica and cutout effects on the axial and lateral buckling responses of carbon/epoxy fiber‐reinforced composite laminates. To this end, specimens manufactured by vacuum bagging after hand layup technique were prepared at various amounts of nano‐silica (0.5%, 1.0%, 1.5%, 2.0%, and 3.0% by weight) incorporated into epoxy resin. Furthermore, semi‐circular and circular cutouts were opened on specimens to understand cutout effect on buckling characteristics of specimens. The results demonstrated that nano‐silica had a significant effect on buckling behaviors of the carbon fiber‐reinforced composites. Regardless of cutout presences, maximum critical axial (393.33 N, 361.67 N, 320 N for W, C and S) and lateral buckling loads (34.67 N, 33 N, 32.33 N for W, C and S), were achieved from the samples having 1.5 wt. % nano‐silica. In specimens having no cutout, maximum improvements of 72.26% in axial and 48.6% in lateral directions were achieved from the specimens having 1.5 wt. % nano‐silica content. A further amount of nano‐silica addition decreased the resistance to buckling of the specimens. Also, the presence of cutouts on the specimens led to decreases in critical loads. The decreases of 1.5 wt. % nano‐silica doped specimens without cutout in the axial and lateral critical buckling loads, respectively, were seen as 22.9% and 7.24% for circular cutout, 8.75% and 5.06% for semi‐circular cutout. It was concluded that cutout processing and nano‐silica additions should be taken into consideration in a material that may be exposed the buckling failures. Highlights: Nano‐silica impact on buckling behaviors of carbon fiber‐reinforced compositesCutout effects on buckling properties of carbon fiber‐reinforced compositesFailure modes of carbon fiber‐reinforced composites with nano‐silica particlesFindings showed that 1.5 wt. % nano‐silica inclusion exhibited the best values for buckling. [ABSTRACT FROM AUTHOR]

Highlights Composite sandwich double‐curved shells (CSDCS) have been extensively employed in the engineering domain of variable temperature environments; consequently, it becomes very significant and essential to present the thermal buckling characteristics of CSDCS to supply some valuable numerical results. The no‐linear strain–displacement relationship due to temperature variation has been taken into consideration based on the Von‐Karman non‐linear strain theory, and Hamilton's principle is adapted to derive the buckling differential equations of the CSDCS. The Navier method is employed to solve the eigenvalue problem for obtaining the critical buckling temperature. Finally, through studying the variation rule of thermal buckling temperature (CBT), several interesting findings on thermal buckling of the CSDCS are shown, as follows: As the h3/h1 rises, the CBTs of CSDCS first decrease then increase. With the increase of radius value, the CBTs of spherical shells decline, the CBTs of models (1,1) and (2,2) of hyperbolic paraboloidal shells are essentially unchanged, but the ones of models (1,2) and (2,1) decrease. As the h2 increases, the CBT progressively grows after the initial reduction. With the increase in aspect ratio, the CBTs for modes (1,1) and (2,1) of CSDCS gradually increase, and the ones of modes (1,2) and (2,2) shows an increase after an initial decrease. The CBTs of CSDCS gradually increase as the shear module of damping layer increases. Thermal buckling of composite doubly‐curved sandwich shells was studied. A solution was proposed to derive the buckling differential equations. The change rules of critical buckling temperature were obtained. [ABSTRACT FROM AUTHOR]

Cristae are high‐curvature structures in the inner mitochondrial membrane (IMM) that are crucial for ATP production. While cristae‐shaping proteins have been defined, analogous lipid‐based mechanisms have yet to be elucidated. Here, we combine experimental lipidome dissection with multi‐scale modeling to investigate how lipid interactions dictate IMM morphology and ATP generation. When modulating phospholipid (PL) saturation in engineered yeast strains, we observed a surprisingly abrupt breakpoint in IMM topology driven by a continuous loss of ATP synthase organization at cristae ridges. We found that cardiolipin (CL) specifically buffers the inner mitochondrial membrane against curvature loss, an effect that is independent of ATP synthase dimerization. To explain this interaction, we developed a continuum model for cristae tubule formation that integrates both lipid and protein‐mediated curvatures. This model highlighted a snapthrough instability, which drives IMM collapse upon small changes in membrane properties. We also showed that cardiolipin is essential in low‐oxygen conditions that promote PL saturation. These results demonstrate that the mechanical function of cardiolipin is dependent on the surrounding lipid and protein components of the IMM. Synopsis: Dedicated proteins are known to control the architecture of the inner mitochondrial membrane; however, the role of specific lipids is less well defined. Here, a combination of methods including tomography and lipidomics is used to characterise the role of lipid composition in defining cristae architecture. As lipid ratios change, a critical breakpoint phenocopies the loss of cristae‐shaping proteins in the IMM of yeast mitochondria.Phospholipid saturation controls membrane mechanical properties and modulates ATP synthase oligomerization.The mitochondria‐specific lipid cardiolipin functionally compensates for increased phospholipid saturation and is required for cristae formation in low‐oxygen environments.A mathematical model for cristae membrane tubules predicts a snap‐through instability mediated by both protein and lipid‐encoded curvatures. [ABSTRACT FROM AUTHOR]

Highlights Lateral buckling, an essential mechanical phenomenon observed in composite beams subjected to specific external loads and boundary conditions, is influenced by various factors including cutout dimension, shape, position, and beam thickness in woven fabric laminated composite cantilever beams. The investigation focused on examining the lateral buckling behavior of beams containing two square or circular cutouts and comparing the experimental critical buckling loads of beams without any cutouts, which yielded results demonstrating a significant level of agreement. Through the experimental analysis, it was determined that square cutouts exhibit superior lateral buckling behavior when compared to circular cutouts. The effects of cutout shapes on lateral buckling analysis on fiber reinforced composites. The effects of cutout location on lateral buckling load on fiber reinforced composites. Comparison of the lateral buckling performances of fiber reinforced composites in relation to the type and position of cutouts. [ABSTRACT FROM AUTHOR]

This paper presents a fiber element analysis model that simulates the structural responses of square steel‐reinforced concrete‐filled steel tubular (SRCFST) short columns under concentric compression including local buckling effects. The method of effective widths is utilized to model the gradual postlocal buckling of the steel tube walls of a SRCFST column loaded axially to failure. A new confinement model is developed for the concrete based on test results, considering the confinement induced by the embedded steel section. This confinement model is incorporated into the fiber model, and its accuracy is verified by experimental results. The accuracy of various confinement models proposed for concrete‐filled steel tubular (CFST) square columns in predicting the performance of SRCFST columns is evaluated. A parametric study is performed to investigate the performance of SRCFST columns with various parameters. The applicability of the design formulas specified in current standards for CFST columns to the design of SRCFST columns is examined. A formula is proposed to predict the strength of SRCFST short columns. The developed inelastic simulation model, confinement model, and design formula are found to yield performance predictions of SRCFST columns with good accuracy. [ABSTRACT FROM AUTHOR]

Graphene is a highly conductive and exceptional material that has shown potential for significantly improving the piezoelectric and mechanical properties of piezoelectric matrix. This paper examines the stability of composite plates surface bonded with graphene‐reinforced composite piezoelectric (GRCP) actuators. However, the significant differences in material characteristics at the interfaces will pose some challenges in analyzing the buckling behavior of piezoelectric composite plates by means of existing higher‐order shear deformation theories. To address this issue, a refined plate theory is developed for the buckling analysis of piezoelectric composite plates. The developed theory includes a new interlaminar shear stress field that precisely describes the distribution of interlaminar shear stresses, which differs from earlier higher‐order theories. It should be emphasized that the finite element formulation can be simplified by removing the second‐order derivatives of in‐plane displacement parameters from interlaminar shear stresses. In terms of the developed theory, a four‐node C0 quadrilateral plate element is introduced to examine the buckling behavior of piezoelectric composite plates. Furthermore, the modified interlaminar shear stress field is absorbed into the strain energy, significantly improving the ability to predict the critical loads of composite plates with GRCP actuators. The refined plate model is evaluated through the utilization of three‐dimensional (3D) elasticity solutions and results obtained from other associated theories. Numerical results demonstrate that the refined plate model is capable of producing favorable results, and a comprehensive examination is conducted to analyze the effects of significant parameters on the buckling behaviors of piezoelectric composite plates. This study sets a solid foundation for future research and development on the application of graphene‐reinforced composite piezoelectric actuators in composite structures. Highlights: Buckling analysis of composite plates with GRCP actuators is conducted.A refined plate theory with modified interlaminar shear stresses is developed.The ability to predict critical loads can be significantly improved.The finite element formulation can be simplified based on the proposed model.Comprehensive parametric studies on buckling behavior are caried out. [ABSTRACT FROM AUTHOR]

In this paper, we study the buckling problem of the drifting Laplacian on bounded domains in a complete Riemannian manifold with nonnegative ∞‐dimensional Bakry–Émery Ricci curvature. According to the property of the manifold, we obtain a family of trial functions. By making use of these trial functions, we derive a universal inequality of eigenvalues, which is independent of the domains. [ABSTRACT FROM AUTHOR]

In this study, we introduce a comprehensive investigation into the buckling behavior of carbon nanotubes (CNTs) using a combined approach of quantum mechanics and molecular mechanics methods. A novel aspect of our research lies in the exploration of the quantum effects of fine scaling on the buckling behavior of finite‐length nanotubes across various dimensions and chiralities. Specifically, we analyze the critical buckling strain variations in CNTs with distinct lengths, diameters, and chiralities, revealing pronounced differences influenced by atomic arrangement and the type of structure used in nanotube construction. Our findings elucidate that at smaller dimensions, nn2$$ \left(\ n,\frac{n}{2}\right) $$ nanotubes exhibit a higher critical buckling strain than other chiralities, while zigzag atomic arrangements demonstrate greater resistance to torsional loading at larger diameters. Additionally, we compare the buckling behavior of nanotubes obtained by wrapping armchair and zigzag nanosheets, highlighting differential resistance trends. This research not only underscores the critical role of quantum effects in determining nanotube buckling but also provides valuable insights into the nuanced influences of atomic arrangement and nanosheet type on the mechanical properties of CNTs. Thus, our work contributes a novel perspective to the field, bridging the gap between quantum mechanics and the mechanical behavior of nanostructures, which has significant implications for the design and application of nanoscale materials [ABSTRACT FROM AUTHOR]

Ensuring the stability of composite structures in the marine environment is crucial. The harsh and corrosive nature of marine conditions presents unique challenges, making maintenance a top priority. In this study, the impact of seawater aging on the mechanical, buckling, structural, and thermal properties of glass fiber‐reinforced polymer nanocomposites was investigated. Composites were produced using the VARTM method with 2% nano Al2O3 and 2% nano TiO2. Aging was conducted in a seawater environment at room temperature for 120, 240, and 360 days. Mechanical properties, including tensile, compressive, flexural, impact, and buckling tests, were performed, and water absorption was determined. Structural analysis was carried out using SEM images. The experimental results indicated that the presence of nanoparticles minimized the effect of seawater. TiO2 preserved tensile strength by 10.33%, impact energy by 6.8%, and critical buckling load by 3.06% compared to the pure composite. Al2O3 reduced water absorption to 0.594% and preserved tensile strength by 6.67%, impact energy by 4.02%, and critical buckling load by 2%. Thermal test revealed an increase in thermal conductivity with aging, with the TiO2‐doped composite exhibiting the smallest increase (14.66%). The significance of the obtained results was confirmed through ANOVA analysis. Highlights: Glass fiber‐reinforced nanocomposite was produced with nano Al2O3 and TiO2.The effect of seawater aging was investigated.It showed that TiO2 nanoparticles are a good candidate against seawater aging.The experimental results showed statistical significance. [ABSTRACT FROM AUTHOR]

Buckling of a simple supported and cantilever nano‐rod and under action of self‐weight was modeled, taking into account the surface effect according to two models of surface elasticity – Gurtin–Murdoch and Steigmann–Ogden. The size effect under the buckling was studied by the Ritz method using two kinematic hypotheses, known as the rod theories of Euler–Bernoulli and Timoshenko. The simulation results were compared depending on the accepted surface elasticity model and the kinematic hypothesis. [ABSTRACT FROM AUTHOR]

This paper presents and analyzes the nonlinear buckling responses of three types of shallow imperfect panels (cylindrical panel, parabolic panel, and half‐sinusoid panel) made from functionally graded graphene reinforced composite (FG‐GRC) on nonlinear elastic foundations subjected to axial compressive load in thermal environments. The nonlinear governing equations are formulated on Reddy's higher‐order shear deformation shell theory (HSDST) and take into account von Karman‐type nonlinearity. A new approximation technique to determine the stress function in average sense is developed and Galerkin's method is used to obtain the algebraically nonlinear equation system. Then, the simple calculation process can be used to solve the obtained equation systems, and the formulations to calculate the critical buckling loads and postbuckling load‐deflection curves are expressed in explicit form. The results can be flexibly applied to FG‐GRC panels with different curvatures in engineering designs. The effects of panel types, geometrical parameters, temperature increase, initial imperfection, and nonlinear elastic foundations on the critical buckling loads and postbuckling curves of cylindrical, parabolic, and half‐sinusoid FG‐GRC panels are discussed in numerical results. Numerical results also show a small disadvantage in the load‐carrying capacity of cylindrical panels compared to parabolic panels and half‐sinusoid shallow panels. Highlights: Postbuckling of cylindrical, parabolic, and half‐sinusoid panels are studied.The panels are made of functionally graded graphene reinforced composite.Reddy's higher‐order shear deformation shell theory is applied.A new approximation technique to determine the stress function is developed.Critical buckling loads and postbuckling expressions are explicitly obtained. [ABSTRACT FROM AUTHOR]

Buckling of the longitudinal rebar is one of the main forms of plastic hinge failure in reinforced concrete (RC) columns after an earthquake. This rebar buckling significantly impacts the seismic bearing capacity and energy dissipation capacity. To restrain the development of longitudinal rebar buckling behavior and delay the degradation of lateral strength in RC columns, this paper developed a new type of buckling restraint rebar (BRR) consisting of three components: longitudinal rebar, a restraint sleeve, and foam material. First, the BRR mechanical properties under compression and tension‐compression cyclic loading were obtained through quasi‐static loading tests. Then, the BRR compression and tension‐compression cyclic loading processes were numerically simulated based on ABAQUS finite element software. The simulated results were compared with the test results. Finally, a stress–strain constitutive model for this new BRR was proposed based on this study. Results showed that the restraint sleeve could significantly enhance the lateral stiffness and the bearing capacity of longitudinal reinforcement after yielding. The compressive performance of BRR was mainly affected by the length and wall thickness of the sleeve. The cyclic performance was mainly affected by the length of the sleeve and the clearance between the sleeve and the reinforcement. The BRR constitutive model proposed in this paper can accurately reflect the influence of restraint sleeves on the stiffness of longitudinal reinforcement after yielding. [ABSTRACT FROM AUTHOR]

This paper presents a novel higher‐order shear deformation beam theory for analyzing the stability and free vibration of functionally graded (FG) sandwich beams with emphasis on the effect of higher‐order moment (HOM) and cross‐sectional warping. The governing equation of axially loaded FG sandwich beams is derived from three‐dimensional equations of the theory of elastic waves in bodies with homogeneous initial stresses. The characteristic equations for typical end conditions are obtained exactly. The numerical results of the natural frequencies and critical loads are calculated and verified for special cases by comparing them with the existing solutions. The effects of gradient index, core thickness, HOM, and warping shapes on the natural frequencies and critical buckling loads are elucidated for different slenderness ratios and end constraints. [ABSTRACT FROM AUTHOR]

Remotely controllable photoresponsive hydrogel actuators are promising for applications in multiple fields. However, simple deformation mechanisms, which rely on the general swelling/deswelling, limit their performance and application. Herein, we report a displacement amplification mechanism based on the buckling deformation of photoresponsive hydrogel film. The on‐chip buckled architecture of the hydrogel enables actuation between a flat 2D shape and tubular 3D buckled shape with remarkable performances, including high deformation ratio (height ratio: ≈360%), tunable cycle motion frequency (0.1—1 Hz) and high cyclic stability. Moreover, localized buckling deformation, such as tube opening and closing, can be controlled in response to photostimulation. Inspired by these biomorphic shapes and motions, an intestine‐mimetic device and demonstrate segmentation with substance crushing and peristalsis motion with substance propelling were further fabricated. This study will provide a useful design principle for hydrogel actuators and shed light on diverse applications in soft robotics, dynamic microfluidics and organs‐on‐chips. [ABSTRACT FROM AUTHOR]

The steel plate shear walls (SPSWs) are reckoned as one of the lateral load‐resisting systems with a high ductility and strength as well as a great energy dissipation capacity, which have been widely used in the recent years. One of the most important drawbacks of the SPSWs concerns their shear buckling due to which the behavioral parameters of this system is considerably undermined. To overcome this issue, the buckling‐restrained (BR) SPSWs have been developed, which have succeeded in resolving the drawbacks of the conventional SPSWs. This paper has investigated behavior of the BRSPSWs subjected to the cyclic loadings. To examine the nonlinear static behavior of the BRSPSWs, four experimental specimens including the specimen without concrete panel, the specimen with concrete panel and gap width equal to zero (directly connected to the steel plate) and the specimens with gap width 20 and 40 mm, were built in the laboratory with a scale of 1:2 and then subjected to the cyclic loadings. Afterwards, the specimens were numerically simulated considering the gap widths 0, 20 and 40 mm. After the process of verification, a parametric study was performed, in which cyclic performance of the specimens subjected to the reversed loadings according to ATC‐24 protocol was investigated. Based on the obtained results, the specimen without concrete panel has the lowest energy dissipation capacity, which is due to the local and lateral buckling. Additionally, the pinching phenomenon was significant in this specimen. In contrast, the specimens with gap width 20 and 40 mm exhibited an energy dissipation capacity six times greater than that of the specimens without panel or even gap. Moreover, it was observed that the shear capacity of the specimens with the concrete panels increased by nearly 50%. [ABSTRACT FROM AUTHOR]

The buckling of new three‐phase composite shells, which include the base material combined with macro fiber composite and reinforced with graphene (MFC‐GP), is investigated in this article. The bifurcation condition of the buckling is obtained by implementing the first‐order shell theory and wave propagation theory in conjunction with the principle of minimum potential energy. The buckling analysis is transformed into a bifurcation problem of equations. Parametric study is conducted to investigate the effects of the GP volume fraction, length, neutral surface radius, and thickness on the critical buckling loads and critical buckling modes. Furthermore, the influences of voltage and temperature change on the critical buckling displacements are explored. Reliable theoretical support for the design and manufacture of the MFC‐GP structures is provided in the results. [ABSTRACT FROM AUTHOR]

This study investigates the effects of nanoclay (NC) particles on the buckling behavior of carbon/Kevlar intraply hybrid composites. The laminates containing various amounts of NC particles (0.5%, 1%, 1.5%, 2%, and 3% by weight) were manufactured using hand layup stacking followed by vacuum bag molding process. The prepared samples were subjected to axial and lateral compressive loads under fixed‐fixed and fixed‐free boundary conditions, respectively, and the relevant critical buckling loads were determined. Furthermore, the failure modes were examined via microscopic views taken from the damaged areas on the samples to fully understand the influences of NC particles on buckling characteristics. The findings demonstrated that the buckling behaviors of the samples were significantly affected by the introduction of NC particles. Compared with the composite samples without any NC particles, the composite samples with 1 wt% NC particles showed an increase of 21.12% and 25.33% in the axial and lateral critical buckling loads, respectively. However, the inclusion of NC particles with an amount that higher than 1 wt% showed a decreasing trend in terms of critical loads for both buckling loadings, which can be viewed as a measure of load‐bearing capability. Moreover, the samples filled with 3 wt% NC particles exhibited a decrement on critical loads compared with those of samples without any NC particle filler. With the help of microscopic views, the failure modes were detected as matrix fragmentation and delamination for both buckling loadings. [ABSTRACT FROM AUTHOR]

In this article, the numerical and experimental results for buckling analysis of a nanocomposite beams reinforced by nanorods are studied and compared. The Chebyshev-Ritz method is used to calculate the buckling numerically and compare it with the buckling test. Epoxy resin, glass's fiber, and nanorods are used to make composites. These nanorods are made using recycled materials. Also, bending and tensile tests are used to obtain the properties of these composites. In addition, the effect of various parameters such as Young's modulus, temperature change, Poisson's ratio, and boundary conditions, the strain gradient parameter, and different shape function is investigated. The addition of nanorods increases the strength and stiffness of composites and increases the critical buckling load. Actually, the made nanorods are used as a reinforcement in matrix, thus in the made nanocomposites, fracture and buckling tests are done and the results indicate that the inclusion of nanorods (0.32%) increases the critical buckling load by 16.4%. A facile hydrothermal method to synthesis the nano rodes has a less cost with the other methods, thus by adding a small percentage of it to the composite, the stiffness of the structure increases. According to the results and the significant increase in Young's modulus and critical buckling load and the cost-effectiveness of carbon nanorods (CNRs) made from recycled materials, these environmentally friendly reinforcements can be used in various industries such as machine body construction, automobile manufacturing, shipbuilding and construction of type's turbines. Highlights • Using potato peels and hydrothermal methods, CNRs produced. • These CNRs are useful, and production is cheap and no harm environmental. • Buckling sample include of glass fiber, without and with CNRs and epoxy resin. • Third order shear deformation beam theory and Chebyshev-Ritz are used • Theoretical and experimental buckling critical load are compared. [ABSTRACT FROM AUTHOR]

The nonlinear vibration and dynamic responses of functionally graded graphene‐reinforced composite (FG‐GRC) laminated cylindrical, parabolic, and sinusoid panels stiffened by FG‐GRC stiffeners in the uniformly distributed temperature variation are presented in this paper. An improved smeared stiffener technique is used to model the added stiffnesses of stiffeners to the total stiffnesses of panels. The higher‐order shear deformation shell theory (HSDT) with the geometrical nonlinearities of von Kármán is applied to establish the governing formulations. The stress function form is estimated using the approximated technique for complex curvature panels. Lagrange function and Euler‐Lagrange equations are applied, and the Rayleigh dissipation function is taken into account to obtain the nonlinear equation of motion. Numerical examples are investigated using the Runge‐Kutta method to obtain the dynamic responses of panels, and the critical dynamic buckling loads of panels are considered using the Budiansky‐Roth criterion. Some significant remarks on the nonlinear vibration and dynamic buckling responses of three types of stiffened panels can be recognized from the numerical examples. [ABSTRACT FROM AUTHOR]

The work is devoted to the study of vibrations and buckling of a graphene sheet (GS) with the shape of a right triangle, and embedded in a nonlinear polymer matrix. The research is based on the nonlocal elasticity theory and the application of the Bubnov‐Galerkin method. Due to the influence of the polymer surrounding, the study of vibrations is reduced to the analysis of a nonlinear cubic ordinary differential equation considering small‐scale effects. The nonlocal buckling problem for the triangular GS under in‐plane uniform compression is investigated including the finding of critical buckling load and the post‐buckling behaviour determined by the nonlinear medium effect. [ABSTRACT FROM AUTHOR]

Grid‐stiffened composite cylinders are widely used in a variety of applications and are subjected to static, dynamic, and impact loads. In terms of buckling strength, these structures outperform simple layered and sandwich composites of the same weight, and the presence of unidirectional fiber ribs contributes to their delamination resistance. The purpose of this research is to look into the buckling behavior of grid‐stiffened composite cylinders under low‐velocity and high‐energy axial impacts. The tests were carried out at room temperature using a 35 kg impactor with an impactor fall height of about 2.75 m. This study builds on previous research and considers the samples' thin skin, indicating that skin buckling is the primary buckling mode in such scenarios. According to static loading research, three types of buckling can occur in grid‐stiffened composite cylinders: local shell buckling, local rib buckling, and general buckling, and each of these can be controlled by adjusting the geometric properties. But, based on the loading speed in the weight‐drop test, controlling the specific type of buckling that occurs during impact loading is difficult. Examining residual structural effects can help determine the type of buckling and damage sustained during impact events. According to the results, the forces that cause buckling in grid‐stiffened composite structures under impact loads are 1.5–2 times greater than static loading conditions. Notably, once the forces are removed, these structures can return to their original positions, however with less stiffness. As a result, they absorb a significant amount of impact energy. Highlights: Composite cylinders with spiral ribs have higher static compression resistance.Dynamic loading increases local buckling forces in grid‐stiffened structures.Despite being damaged, grid‐stiffened cylinders bounce back quickly after impact.Skin buckling is a common mode of failure for grid‐stiffened composite.The global buckling force is greater than the local buckling force. [ABSTRACT FROM AUTHOR]

A design concept is proposed for the building block, a dot, of programmable braille readers utilizing bistable shell buckling, magnetic actuation, and pneumatic loading. The design process is guided by Finite Element simulations, which are initially validated through precision experiments conducted on a scaled‐up, single‐shell model system. Then, the simulations are leveraged to systematically explore the design space, adhering to the standardized geometric and physical specifications of braille systems. The findings demonstrate the feasibility of selecting design parameters that satisfy both geometric requirements and blocking forces under moderate magnetic fields, facilitated by pneumatic loading to switch between the two stable states. While the study is focused on experimentally validated numerical simulations, it is also identify several manufacturing challenges that need to be resolved for future physical implementations. [ABSTRACT FROM AUTHOR]

The post‐buckling strength, which is simply called as crippling, is investigated for laminated composite structures in this study. L profiles that had various stacking sequences of carbon fiber reinforced epoxies were tested. Three different layups configurations were used by changing flange‐to‐thickness ratios. The main objective of this research was to show that flange‐to‐thickness ratio was not the only effecting parameter for crippling. Therefore, a new parameter, EGY number, was developed by considering the positions of 0° and 45° plies. Depending on EGY number, a new semi‐empirical formulation was presented to calculate crippling strength of the laminated composite structures. One of the test results was employed to verification of EGY number. In addition, the test results were validated with finite element analyses. Static, Riks and Dynamic, Explicit computational results were compared to simulate the experiments. Highlights: Determination of crippling strength both experimentally and theoretically.Comparison of numerical models: Static, Riks versus Dynamic, Explicit.Developing a new parameter called as EGY number.Developing of a new analytical semi‐empirical formula for crippling strength. [ABSTRACT FROM AUTHOR]

Based on Eringen's nonlocal elastic theory, the vibration characteristics and critical buckling load of porous functionally graded rectangular nanoplates under thermomechanical load are studied. The material properties of porous FGM nanoplates are characterized by Voigt mixing power rate and arbitrarily distributed porous model, and the correlation between material and temperature is further considered, the temperature distribution along with the thickness direction is uniform. The numerical solution of the vibration and critical buckling loads of porous functionally graded material (FGM) rectangular nanoplates under thermo‐mechanical loading are investigated using the numerical solution method‐differential transformation method (DTM), and the governing differential equations are established in the classical plate theory and Hamilton system. The effects of boundary conditions, nonlocal parameters, gradient index, temperature rise, porosity, compression load, and aspect ratio on the vibration and critical buckling load of porous FGM nanoplates under thermo‐mechanical loading effects are mainly investigated utilizing arithmetic examples. [ABSTRACT FROM AUTHOR]

Even though the simulations used to describe the failure of laminates are becoming more and more predictive, complex testing under multiaxial loadings is still required to validate the design of structural parts in a wide range of industrial domains. It is thus essential to assess the actual boundary conditions to allow for an objective comparison between testing and calculations, in particular since the structural tests are complex and often leads to buckling. Therefore, accurate estimation of force and moment fluxes applied to the specimen is critical. In this context, stereo digital image correlation (SDIC) has proven to be an important measurement tool and provides very well‐resolved surface displacement fields, but the exploitation of such measurements to calculate fluxes remains problematic when testing composites. The first objective of this study is both to reduce the uncertainty associated with fluxes determination on a complex test and to simplify the extraction process with respect to existing procedures. The second objective is to make this methodology robust to geometrically non‐linear deformations. In this paper, we propose a new methodology that extracts minimal boundary conditions in the form of 3D mechanically admissible displacements fields. The approach developed uses a finite element SDIC (FE‐SDIC) method regularized by means of mechanical behaviour admissibility equations. Results show that the new methodology outputs much more accurate fluxes than classical data generated from multiple differentiations of the displacement fields. Excellent noise robustness is obtained and quantified. Numerical predictions have been satisfactorily compared with experimental data from one structural‐scale composite specimen under complex testing. [ABSTRACT FROM AUTHOR]

Flexible wearable sensors have the characteristics of flexibility, comfort, and wearability, and have shown great potential in future electronic products. Despite significant efforts in developing stretchable electronic materials and structures, the development of flexible strain sensors with a wide temperature range, high sensitivity, broad detection range, and good interface stability remains challenging. Here, strain sensors with buckled structures are fabricated using high and low‐temperature resistant material Ti3C2Tx MXene/graphene, PDMS 184. The conductive material Ti3C2Tx MXene/graphene exhibits excellent interface interaction with PDMS 184, addressing not only the poor compatibility issue between the conductive material and the flexible substrate, but also demonstrating good stability and cycling performance. Buckled structure improves the stretchability and linearity of strain sensors. The fabricated strain sensor is suitable for a wide temperature range (−40 to 120 °C) and exhibits high stretchability (120% strain). The strain sensor demonstrates rapid response times at different temperatures: −40 (72.6 ms), 0 (62.7 ms), and 120 °C (52.7 ms). The strain sensor exhibits high sensitivity at different temperatures: −40 (GF = 0.38), 0 (GF = 0.24), 40 (GF = 0.66), and 120 °C (GF = 1.47). The strain sensor has a wide detection range (0.1% to 120%) and excellent cycling stability. In addition, Ti3C2Tx MXene/graphene strain sensors can accurately capture various human activities, such as blinking, speaking, finger bending, and wrist bending. [ABSTRACT FROM AUTHOR]

The moiré effect arises from the superposition of periodic structures with differences in periods or angles. Although the moiré effect can be exploited as an intriguing tool to fabricate complex metastructures, reduction of the moiré effect can be an important issue in display technology that uses many optical films with periodic patterns. Because of the superposition, dark and bright regions can be seen by the naked eye, which is a reason for the degradation of the visual quality. In this work, the lateral deformation of shape edges of prism films is harnessed to reduce the moiré effect. After the preparation of a microprism array with hydrogel materials, the hydrogel microprism array is swelled via penetration of water molecules into the hydrogel networks. Due to the compressive stress applied by volume expansion with confinement, only the sharp edges laterally buckle randomly. The swollen hydrogel prism array is replicated by photopolymerization, and prism arrays with laterally buckled edges are obtained. The randomized edges help reduce the moiré effect of the optical film when the prism array is overlapped with other periodic devices, such as other prism arrays or display devices consisting of microscale pixels, without a significant decrease in the optical performance. [ABSTRACT FROM AUTHOR]

The present research investigates lateral stability of a functionally graded nanobeam using Eringen's differential nonlocal elasticity model under rigid (clamped, pinned, free) and deformable (lateral, rotational restraints) boundary conditions. Sigmoid and power law have been employed as grading laws to study the influence of the material distribution on the snap‐buckling analysis of a nanobeam with arbitrary boundary conditions. Moreover, Fourier sine series with Stokes' transformation are employed to investigate the effects of boundary conditions on the stability response of nanobeams embedded in a Pasternak foundation. A parametric study has been performed to investigate the effect of deformable boundaries, Pasternak foundation and small‐scale parameters on the stability response of the nanobeam and the results have been presented in a series of tables and figures. It has been observed that consideration of the small‐scale parameter, Pasternak foundation, deformable boundaries and functionally grading index (of sigmoid and power‐law) are essential while analyzing the static stability response. The obtained analytical results may be used as benchmarks in future researches of functionally graded nanobeams embedded in an elastic medium. [ABSTRACT FROM AUTHOR]

Within the framework of the consistent couple stress theory (CCST), we develop a Hermitian Cn (n = 1, 2) finite cylindrical layer method (FCLM) for carrying out the three‐dimensional (3D) analysis of the size‐dependent buckling and free vibration behaviors of simply supported, functionally graded (FG) piezoelectric cylindrical sandwich microshells. The microshells of interest are placed under closed‐circuit surface conditions and subjected to axial compression and electric voltages. We derive a 3D weak formulation based on Hamilton's principle for this study. In the resulting formulation, the microshell is artificially divided into nl microlayers, with the elastic displacement components and the electric potential selected as the primary variables. By incorporating a layer‐wise kinematic model into our weak formulation, we develop a Hermitian Cn FCLM, which can be used for analyzing FG piezoelectric cylindrical sandwich microshells. Each primary variable is expanded as a double Fourier series in the in‐surface domain and is interpolated in the thickness direction using Hermitian Cn polynomials. The accuracy and the convergence rate of our Hermitian Cn FCLMs are validated by comparing the solutions they produce for FG piezoelectric cylindrical macroshells and FG elastic cylindrical microshells with the relevant exact and approximate 3D solutions which have been reported in the literature. The material length scale parameter of our FCLMs is set at zero in the comparison made with the FG piezoelectric macroshells. In contrast, the piezoelectric and flexoelectric effects are ignored in the comparison made with the FG elastic microshells. The impact of some essential factors on the critical load, critical voltage, and natural frequency of simply supported FG piezoelectric cylindrical sandwich microshells is assessed. The important factors are identified as piezoelectricity, flexoelectricity, the material length scale parameter, the inhomogeneity index, the radius‐to‐thickness ratio, the length‐to‐radius ratio, and the magnitude of the applied voltage and the applied load. [ABSTRACT FROM AUTHOR]

This study investigates the buckling of microbeams with variable cross‐sections and middle supports in a thermal environment. Based on classical theories and modified couple stress, the size‐dependent behavior of the microbeam is modeled, and the intermediate support is simulated elastically. A temperature‐dependent relationship will also be assumed for the material properties of the microbeam. The governing equations will be derived using Hamilton's principle based on the modified Couple stress theory and the nonlinear thermal field. Using an analytical approach, buckling loads and deformation of microbeams will be determined. The accuracy of the answers will be investigated to demonstrate the effectiveness of the method used and the correctness of the results obtained. A comparison will be made between the obtained results and the results available in the scientific literature to prove the accuracy of the formulation and the method used. A parametric study will then be conducted to determine the effect of boundary conditions, the flexibility of the middle support, temperature distribution, and geometric characteristics on the buckling loads of microbeams. [ABSTRACT FROM AUTHOR]

Nonlinear buckling and postbuckling of longitudinally compressed carbon nanotube‐reinforced (CNTR) cylindrical shells stiffened by longitudinal or circumferential CNTR stiffeners in thermal environments surrounded by elastic medium are presented in the present study. Five linear distributions of CNT are considered for the shell‐stiffener structure system and they are modeled by innovation homogenization technique for CNTR stiffeners. Based on the classical Donnell thin shell theory with von Karman's nonlinearities and the Galerkin procedure, the governing equations can be built to analyze the critical buckling compression and postbuckling compression‐deflection and compression‐shortening behavior. The noticeable effects of volume fraction of CNTs, shell‐foundation interaction stiffnesses, uniformly distributed temperature, and geometric properties of stiffened cylindrical shells on the critical buckling compression and compression‐deflection and compression‐shortening postbuckling behaviors of stiffened CNTR cylindrical shells are obtained and remarked in numerical examinations. [ABSTRACT FROM AUTHOR]

The axial buckling load of single carbon fiber or composite strands is typically predicted using Euler's formula, developed for isotropic materials. This study introduces anisotropy in a mechanical carbon/epoxy Z‐pin model under axial pressure. It examines the influence of compressive modulus, shear modulus, off‐axis angle, and aspect ratio on its buckling behavior. Results show that the axial instability performance of the Z‐pin decreases with lower compression, shear modulus, and aspect ratio while keeping the tensile modulus fixed. Anisotropy decreases buckling load by up to 14% compared with Euler's formula, which only considers tensile modulus. Additionally, the impact of the deflection Angle between the pressure and pin‐axis can be ignored when it is less than 3°. Highlights: Euler formula overestimates composite Z‐pin buckling force under axial pressure.Anisotropy decreases buckling load by up to 14% for carbon/epoxy.Shear modulus is more influential on Z‐pin with a small aspect ratio.For off‐axial compression angles <3°, influence can be ignored. [ABSTRACT FROM AUTHOR]

Present study aims to investigate the mechanical buckling including the shear buckling and the in‐plane mechanical buckling of composite laminated plates reinforced with graphene sheets with temperature dependent features resting on Winkler‐Pasternak elastic foundation in a thermal ambient. The governing equations in the framework of the first order shear deformation theory are attacked by the Ritz method. The plate is subjected to uniaxial, biaxial and shear loads. The innovation of the present paper is considering the temperature dependency and anisotropicity of the material properties of a nanocomposite layer that reinforced with graphene sheets for the purpose of the determination of the mechanical buckling treatment of a graphene reinforced composite (GRC) laminated plate with different boundary condition types. Resorting to the extended Halpin–Tsai micromechanical model, the thermo‐mechanical characteristics of a lamina is defined. Numerical outcomes of the present study are confirmed with the presented data in the literature. The effects of the elastic foundation parameter, the temperature, the plate side to its thickness ratio, the layup scheme, the boundary condition type and the distribution pattern of graphene‐reinforced composites on the critical buckling load are investigated. It is found that, the impact of elastic foundation incorporation is less visible on the critical shear buckling load rather than the critical uniaxial and biaxial mechanical loads. Moreover, the largest critical buckling load belongs to layup [0]10 among the all under studied lamination schemes. [ABSTRACT FROM AUTHOR]

Sunscreens provide a frontline defense for our DNA against the damage caused by ultraviolet (UV) radiation. The active ingredients in topically applied sunscreens that provide this defense are UV filters, which preferentially absorb or reflect UV radiation before it penetrates the skin and interacts with photosensitive nucleic acids. However, there are concerns related to human and environmental toxicity of current UV filters, and consequently a shift toward nature‐inspired, particularly microbial, UV filters. In this paper, new physical insight is provided into the fundamental mechanisms of photoprotection in two synthetic analogs of mycosporine‐like amino acid‐type UV filters, demonstrating new methods of protection that are distinct from those of current commercial sunscreens, extending previous work in this area. Transient absorption measurements (both transient electronic absorption spectroscopy and transient vibrational absorption spectroscopy) are combined with steady‐state studies and high‐level computational results to aid our mapping of the experimentally derived lifetimes to real‐time photodynamic processes. The conclusions reached here pave the way toward developing new and more efficient biomimetic DNA photoprotectant materials. [ABSTRACT FROM AUTHOR]

Induction heating has many engineering applications. To accurately describe the induction heating process of thin steel sheets one needs to account for their mechanical deformation. This might strongly affect the magnetic configuration since thin sheets are prone to thermal buckling, leading to large supercritical deformations. We suggest a modelling strategy combining a computationally highly efficient structural mechanical shell description for the thin sheet with a standard continuum model for eddy current and thermal problems through an iterative coupling algorithm. All benchmark problems are solved numerically using the finite element method. [ABSTRACT FROM AUTHOR]

The functionalized multi‐walled carbon nanotubes (MWCNTs) (0.5–5 wt.%) are compounded with high density polyethylene (HDPE), and, subsequently, used for extruding nanocomposite filaments to fabricate nanocomposites (NCs) and functionally graded nanocomposites (FGNCs) through 3D printing. The 3D printed NCs are investigated for coefficient of thermal expansion (CTE), and buckling under different non‐uniform temperature distributions (case‐1: left edge heating, case‐2: centre heating, and case‐3: left and right edge heating). A significant reduction in CTE is observed with MWCNT addition and gradation. The highest reduction in CTE is observed for H5 (5 wt.% of MWCNT in HDPE) NC and H1 ⟶ H3 ⟶ H5 (FGNC‐2) among the NCs and the FGNCs. It is noted that Tcr (critical buckling temperature) is highest for case‐3 and lowest for case‐2. The highest deflection is noticed in case‐2, while no significant difference is observed in case‐1 and case‐3 heating conditions. It is also observed that Tcr increases with gradation and MWCNTs addition. The H5 NC and FGNC‐2 exhibited the highest Tcr among the NCs and FGNCs, respectively. The maximum deflection is noticed for HDPE, whereas the minimum deflection is noticed for FGNC‐2 and H‐5 NC among the tested samples. The results also revealed that Tcr is very sensitive to type of heating. [ABSTRACT FROM AUTHOR]

Aim: To evaluate the bending, buckling and torsional resistance of ProGlider (PG) (Dentsply Sirona, Ballaigues, Switzerland), R‐Pilot (RP) (VDW, Munich, Germany) and WaveOne Gold Glider (WOGG) (Dentsply Sirona). Methodology: Ninety instruments were used: 30 PG (size 0.16,.02v taper), 30 RP (size 0.125,.04 taper) and 30 WOGG (size 0.15,.02v taper). The bending resistance test was performed on 10 randomly selected instruments of each system according to ISO 3630‐1 specifications. For the buckling resistance test, a loading was applied in the axial direction of each instrument using a universal test machine, with a 20 N cell and 15 mm min−1 speed, in the axial direction. When a lateral elastic displacement of 1 mm occurred, the force was registered. The torsional resistance test was performed according to ISO 3630‐1 specifications. Statistical analysis was performed using one‐way anova and post hoc Student–Newman–Keuls test (P < 0.05). Results: WOGG had the lowest bending resistance, whilst RP had the highest bending resistance (P < 0.05). RP also had the highest buckling resistance, and WOGG had the lowest (P < 0.05). PG had intermediate results regarding bending and buckling resistance, with significant differences to RP and WOGG (P < 0.05). RP had the highest torsional strength and the lowest angular deflection when compared to PG and WOGG (P < 0.05). No differences in the torsional strength and angular deflection were observed between WOGG and PG (P> 0.05). Conclusion: The glide path instruments had different behaviours in term of bending, buckling and torsional resistance. [ABSTRACT FROM AUTHOR]

An analytical study on buckling of carbon nanotube reinforced composite (CNTRC) circular cylindrical shells and toroidal shell segments surrounded by elastic media, exposed to thermal environments and subjected to axial compression and combined mechanical loads is presented in this paper. Carbon nanotubes (CNTs) are reinforced into isotropic matrix through uniform and functionally graded distributions. Material properties of constituents are assumed to be temperature dependent and effective elastic moduli of CNTRC are estimated by an extended rule of mixture. Formulations are based on first order shear deformation theory taking into account interaction between the shell and surrounding medium. Two‐term solution of deflection is assumed to satisfy simply supported boundary conditions and Galerkin method is used to obtain closed‐form expressions of buckling loads. Numerical illustrations are given to analyze the effects of CNT volume fraction and distribution patterns, preexisting loads, surrounding elastic media and geometrical parameters on the stability of CNTRC shells. The proposed approach is simple and effective to evaluate buckling loads of moderately thick closed nanocomposite shells under different types of mechanical loads. [ABSTRACT FROM AUTHOR]

Controlling adhesion on demand is essential for many manufacturing and assembly processes such as microtransfer printing. Among various strategies, pneumatics‐controlled switchable adhesion is efficient and robust but currently still suffers from challenges in miniaturization and high energy cost. In this paper, a novel way to achieve tunable adhesion using low pressure by inducing sidewall buckling in soft hollow pillars (SHPs) is introduced. It is shown that the dry adhesion of these SHPs can be changed by more than two orders of magnitude (up to 151×) using low activating pressure (≈−10 or ≈20 kPa). Large enough negative pressure triggers sidewall buckling while positive pressure induces sidewall bulging, both of which can significantly change stress distribution at the bottom surface to facilitate crack initiation and reduce adhesion therein. It is shown that a single SHP can be activated by a micropump to manipulate various lightweight objects with different curvatures and surface textures. Here, it is also demonstrated that an array of SHPs can realize selective pick‐and‐place of an array of objects. These demonstrations illustrate the robustness, simplicity, and versatility of these SHPs with highly tunable dry adhesion. [ABSTRACT FROM AUTHOR]

The structural response of slender reinforced concrete (RC) structures may be highly nonlinear due to cracking, reinforcement yielding, and geometrically nonlinear effects. While advanced models can simulate the detailed response of such structures, they are generally ill‐suited for limit state verification in practical design scenarios due to a high computational and modeling effort. A design‐oriented method for evaluating the geometrically linear response of cracked RC wall structures was recently presented and demonstrated to allow the analysis of large‐scale models with more than 2400 finite shell elements within minutes on a standard personal computer. This paper proposes a design‐oriented numerical method for efficient instability analysis of slender RC wall structures, also enabling the inclusion of thermal effects. Based on a two‐step linearized buckling analysis, the method first determines the geometrically linear structural response by solving the complementary energy minimization problem, including, if relevant, thermal strains and reduced material stiffness. This solution is used to derive the sectional stiffness upon which a linearized buckling problem is formulated and subsequently solved as a linear eigenvalue problem. The model is validated using examples with exact solutions, and its applicability to large‐scale models is demonstrated through an example with a four‐story stairwell modeled using more than 3200 finite elements. [ABSTRACT FROM AUTHOR]

Background: To assess rhegmatogenous retinal detachment (RRD) surgery trends and training among young ophthalmologists (YOs, vitreoretinal fellows or attendings/consultants with ≤10 years of independent practice) and the impact of the COVID‐19 pandemic. Methods: An anonymous online survey was completed by 117 YOs in the Asia‐Pacific regarding their RRD surgery experiences in 2021–2022. Results: To achieve a 90% probability of surgical competency, 91 vitrectomy and 34 scleral buckling (SB) completions during fellowship were needed. In total, 49 (41.9%) YOs had fellowship affected by COVID‐19. In the COVID versus pre‐COVID era, however, the volume of SB completions per fellowship year decreased significantly (median [IQR] 3.3 [1.5, 9] vs. 13 [6.5, 23]; p < 0.001) and was lower than the required volume to achieve competency. YOs were less confident in conducting SB versus vitrectomy (3.5 ± 1.1 vs. 4.2 ± 0.8, p < 0.001), and they reported a decrease in the proportion of SB (−3.1%, p = 0.047) and an increase in the proportion of vitrectomy (+4.8%, p < 0.001) after the pandemic outbreak. Apart from RRD clinical characteristics, surgical confidence is among the main factors that affect surgical method decisions. During the pandemic, more YOs may have avoided SB due to the need for general anaesthesia, leading to longer surgical time and risk of viral transmission during intubation/extubation. Conclusions: SB surgical exposure is suboptimal in most fellowship programs in the 11 Asia‐Pacific countries/regions we surveyed and further declined during the COVID‐19 pandemic. YOs are less confident in performing SB, leading to a trend toward primary vitrectomy since the COVID‐19 outbreak. [ABSTRACT FROM AUTHOR]

The benefits of tailored lattice topologies are limited in elevated temperature conditions without a clear understanding about the interplay between the metamaterial structure and the creep response of the base material. This study showed that the metamaterial structure causes the lattice compressive creep behavior to differ largely from that of bulk structures of the same base material. Inconel 625 FCCZ lattices and solid round bar specimens were crept in compression at two elevated temperatures and at three stress levels. The solid round bar specimens experienced only small increases in the steady state creep rate with a steady state exponent of 0.35 and 0.63 at 550°C and 650°C. The solid round bar specimens did not exhibit a deformation mechanism change over the temperatures and stress levels tested. The FCCZ lattices exhibited much larger changes in creep rates with changing stress and temperature with a steady state exponent of 18.3 and 20.2 at 550°C and 650°C, respectively. Additionally, the lattice specimens experienced three different failure behaviors with increasing temperature and stress from stable creep, to progressive buckling, and finally rapid collapse. Highlights: Compressive creep rupture life of lattices were temperature and stress dependent.Topology of the lattice dominated compressive creep behavior compared to base material.Magnitude of initial strut deflection controlled creep life of lattice specimens. [ABSTRACT FROM AUTHOR]

The article discusses the challenges facing Turkish agriculture due to the aging population and climate change. The aging population in rural areas, where the average age of farmers is 58.1, is leading to a decline in agricultural production. The reliance on manual labor and the lack of younger farmers with necessary skills pose a threat to the sustainability of farming. Additionally, climate change and environmental decline further exacerbate the situation. The article also mentions the use of migrant labor in agriculture, but highlights the precarious conditions and limited capacity of this solution. The growing protectionism in agricultural markets and the need for better regulation and support from the government are also discussed. Overall, the article emphasizes the need for a comprehensive and sustainable approach to address the challenges facing Turkish agriculture. [Extracted from the article]

Summary: In this work, the elastic buckling of porous solids was investigated using a lattice spring model (LSM). The capability of the LSM to solve elastic buckling problems was comprehensively verified by comparing well‐established numerical and analytical solutions. Following this, the buckling of a porous solid was studied, in which two porous structures were considered, ie, the random porous model and the Voronoi porous model. The results reveal that both the porosity and the shape of the pores influence the elastic buckling bearing capacity of the porous solid. Finally, the mechanical responses of a porous solid with an extra high porosity (0.85) were numerically investigated. Our numerical results demonstrated that the nonlinear elastic response of the porous solid might come from its mesoscale elastic buckling. This work shows the ability and promise of using the LSM as a fundamental numerical tool for the deep investigation of the buckling mechanical behavior of porous solids. [ABSTRACT FROM AUTHOR]

Current stability evaluation methods are unable to consider the progressive developing process of the bulking landslide and lack progressive evaluation method. Based on the strain‐softening constitutive model and energy conservation theory, this study proposes a progressive evaluation method for buckling landslide stability considering the shear mechanical characteristics of the slip zone with large displacement, enabling progressive evaluation of landslide stability as the buckling landslide deforms. Proposed method was validated based on the good agreement between evaluation result and observation from the critical displacement of Baiyangou landslide in the Three Gorges Reservoir area in China, as a case study. The results also suggest a displacement distribution along the slip zone presenting a two‐step growth feature from the front edge to rear edge; in contrast, the shear strength distribution presents a two‐step decline feature. In addition, the parameter sensitivity analysis of slip zone and slide mass of buckling landslide shows that buckling landslide stability is directly proportional to the thickness of slip zone and elastic modulus of slide mass and inversely proportional to the length of slide mass. [ABSTRACT FROM AUTHOR]

This research aims to explore the buckling performance of a co‐cured and stiffened composite structure with embedded multilayer damping membranes (CSCSEMDM) under static load. A buckling model of this structure is established theoretically by using the principle of minimum potential energy and first‐order shear deformation theory. Then, the governing equation of the structure is obtained. The critical buckling load of the structure is solved, and the finite element method is used to verify the correctness of the theoretical model and theoretical methods. Finally, the effects of various parameters on the critical buckling load are discussed on the basis of the validated model. [ABSTRACT FROM AUTHOR]

Optimizing the core thickness of a sandwich structure can be a computationally expensive task. In this work, an optimization approach for slender columns is presented. The approach iteratively determines the optimal thickness distribution using the second derivative of the eigenmodes as an input for the shape function. To demonstrate its capabilities, it is applied to simple columns constrained according to Euler's buckling cases. The optimization results are validated with detailed finite element models and compared to those from a nonlinear least squares‐based optimization. [ABSTRACT FROM AUTHOR]

This study aims to investigate the hydrothermal effect on the buckling behavior of glass/aramid/epoxy hybrid composites under distilled and seawater environments. The four types of composite groups ([G6]S, [A6]S, [G3A3]S, [A3G3]S) produced by vacuum infusion method were immersed in distilled and seawater at 25 and 70°C for 1000 h. The buckling test was carried out for dry, wet, and redried conditions. The periodic measurements showed that as temperature increases, the maximum water gain ratios also increase for all composite groups. Furthermore, the water absorption parameters were affected by the type of fluids. The buckling test results showed that both temperature and fluid type are effective on the critical buckling load of specimens. The increase in the critical buckling load of the hybrid samples tested in the redried state was less than the samples tested in the wet state for both temperatures. Moreover, the critical buckling loads of the composites aged in seawater were higher than the composites aged in distilled water. [ABSTRACT FROM AUTHOR]