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Three-dimensional lattice structures with high specific strength, specific stiffness and low apparent density, are widely employed across multiple engineering fields. Under uniaxial compressive loading, the lattice structure may experience local buckling or global buckling. This paper conducted a systematic parametric study of the various factors affecting the buckling behavior of multilayer pyramid lattice structures to investigate the mechanism of the two main instability modes, local and global buckling. It was found that the critical buckling load increases with the increase in the size of the unit cell and decreases with the increase in the total height of the structure for the same relative density. As the relative density increases, the buckling resistance of the lattice structure increases. It is possible to examine various buckling modes by varying the geometrical properties of the pyramid unit cell (slenderness ratio, rod inclination angle, cross-sectional size of strut connection parts). Finally, numerical simulations were performed to calculate the yield strength and buckling strength of the lattice structure under uniaxial compression load, in order to estimate the threshold relative density for structural buckling and yield failure. The results demonstrated that buckling failure should be considered for aluminum alloy pyramid lattice when the relative density is below 4.07%. This study provides design criteria for lattice structures dominated by buckling and offers ideas for improving the buckling capacity of truss-type lattice structures. HIGHLIGHTS: Global and local buckling failures of lattice structure were studied Structure height and unit cell size have significant effects on both buckling mode and critical buckling loads Analyzed the threshold relative density for two failure modes of buckling and yielding [ABSTRACT FROM AUTHOR]

In this paper, the thermomechanical buckling and vibration analysis are investigated for carbon nanotube‐reinforced composite sandwich doubly curved shells (CNCSDS) under the action of both thermal loads and in‐plane compressive loads. Based on the von‐Karman non‐linear kinematic relations, First Order Shear Theory, and Hamilton's principle, the vibration and stability equations for CNCSDS under thermomechanical loads are deduced. For obtaining the critical thermomechanical buckling load and vibration frequency, an exact method is adopted. Subsequently, the results are validated by comparing with the finding in published literature and simulation results. At last, the influence of system parameters on critical thermomechanical buckling load and vibration frequency is studied and displayed graphically. Meanwhile, some new results about thermomechanical buckling and vibration analysis of CNCSDS are proposed for the first time. Highlights: Thermomechanical buckling and vibration of carbon nanotube‐reinforced composite sandwich doubly curved shells was studied.Vibration and stability equations under thermomechanical loads was deduced.The change rules of thermomechanical buckling load and frequency were obtained. [ABSTRACT FROM AUTHOR]

The critical buckling load determination of Euler-Bernoulli beams on two-parameter elastic foundations (EBBo2PFs) is important to avert buckling failures. The governing equation for buckling of thin beam on two-parameter elastic foundation is a homogeneous ordinary differential equation (HODE) of fourth order and constant parameters when the beam is prismatic and homogeneous. The HODE has been solved in this work by Galerkin method for simply supported, clamped and clamped-simply supported ends. One-parameter algebraic shape function formulation was used to reduce the problem to an algebraic eigenvalue problem, which is solved to find the critical buckling load for each studied case. The critical buckling load for EBBo2PF for simply supported boundary conditions was found to be closely identical to the exact solutions. The solutions for clamped-clamped edges and clamped-simple supports were found to be accurate. The merit of the Galerkin method is the simplicity and the accuracy even when one-parameter shape function has been used. [ABSTRACT FROM AUTHOR]

Based on the surface elasticity theory combined with the theories of Kirchhoff plate and Mindlin plate, the influences of surface effects on the buckling and post-buckling behaviors of nano-laminates are studied. Analytical solutions for critical buckling loads under uniaxial and biaxial compressions are obtained. Furthermore, approximate solutions for critical post-buckling loads under moveable and immoveable edge conditions are provided by using the Galerkin's method. Numerical examples are given to study the influences of thickness, number of layers, surface parameters and the length of the nano-laminates on buckling and post-buckling critical loads. Results obtained indicate that the surface/interface energy is connected with the number of layers. In addition, the effects of the surface/interface energy on the critical loads enhance through increasing the length of the laminates but reduce by increasing the thickness. Mechanical model, analytical method and conclusions of this work are helpful for designing and examining the stability of the nano-laminates and nanoscale devices. [ABSTRACT FROM AUTHOR]

Steel jacking pipes are potentially prone to buckling instability, a phenomenon that has received limited attention in hard rock formations. This study reports on the field monitoring of a water pipeline project in Zhongshan City, where the circumferential and hoop strains of steel pipe segments jacked in hard rocks were recorded. The buckling deformation observed during steel pipe jacking, as well as the critical buckling load, was analyzed with the aid of numerical simulations using finite element software. The initial defect for the post-buckling analysis of the steel pipe was selected as the first-order buckling mode. Field monitoring revealed that the loading conditions experienced by the steel pipe segments during the jacking process are complex, leading to significant deformation. Throughout the monitoring process, axial stress at each measurement point underwent tensile-compressive transitions. Numerical results showed the actual critical buckling load increases with wall thickness at a constant length-to-diameter ratio, which is significant for short pipes. For pipes with the same wall thickness and outer diameter, the actual critical buckling load of long pipes is significantly lower than that of short pipes. Additionally, initial defects were found to significantly reduce the actual critical buckling load of the steel pipe. Furthermore, the actual critical buckling load of long pipes is much lower than their yield load, whereas, for short pipes, the critical buckling load is limited by their yield load. Measures for managing buckling deformation of steel pipes in situ were also reported. The findings on critical buckling load and the countermeasures for managing buckling in situ would be valuable for the design and construction stages of similar projects employing pipe-jacking technology in hard rock formations. [ABSTRACT FROM AUTHOR]

The straight part of the corrugated steel plate (CSP) pipe-arch structure in soil may cause local buckling instability due to insufficient load-bearing capacity. Recently, composite CSP pipe-arch has been widely utilized to enhance structural stability, and their stability needs to be thoroughly investigated. This paper studies the local buckling stability problem of the straight part of composite CSP pipe-arch in soil by simplifying the soil support and introducing the inter-layer bonding effect. Based on elastic stability theory, a theoretical mechanical model of composite CSP pipe-arch was proposed. The Rayleigh–Ritz method and the semi-combined composite structure stiffness approximation were used to derive the critical buckling conditions for the straight part of the composite CSP pipe-arch. Through numerical calculation and influencing factors analysis, it is concluded that the critical buckling load of the straight part of the composite CSP pipe-arch structure is affected by the elastic modulus, thickness, Poisson's ratio, rotational restraint stiffness and side length of the straight part of the material. In particular, it is found that as the inter-layer bonding coefficient increases, the critical buckling load is improved, while the critical buckling wave number is mainly influenced by the width of the straight part, elastic modulus, and inter-layer bonding coefficient. Additionally, we discussed the coupling effect of several key parameters on the stability of the structure. The results of this study offer theoretical foundations and guidance for the application of composite CSP pipe-arch in soil engineering, such as culverts, tunnels, and pipeline transportation. [ABSTRACT FROM AUTHOR]

In underground spaces, corrugated steel plate (CSP) pipe-arches may experience local buckling instability, which can subsequently lead to the failure of the entire structure. Recently, sandwich CSP pipe-arches have been used to enhance the stability of embedded engineering outcomes, and their buckling behaviors require in-depth research. In this paper, we establish a theoretical model by simplifying soil support and using Hoff sandwich plate theory to focus on the local buckling stability of the straight segment in embedded sandwich CSP pipe-arches using the Rayleigh–Ritz method. Through stability analysis, the instability criteria for embedded sandwich CSP pipe-arches are analytically determined. Numerical calculations reveal that the critical buckling load of a sandwich CSP pipe-arch is affected by several factors, including the elastic modulus, thickness, Poisson's ratio, rotational constraint stiffness, and the length of the straight segment. Specifically, increasing the thickness of the sandwich CSP pipe-arch can substantially enhance the critical buckling load. Meanwhile, the wavenumber is affected by the elastic modulus and the length of the straight segment. The analytical results are in agreement with those obtained from finite element analysis. These findings provide a theoretical basis and guidance for the application of sandwich CSP pipe-arches in fields such as subway stations, tunnel construction, underground passages, and underground parking facilities. [ABSTRACT FROM AUTHOR]

In this paper, critical buckling analysis and nonlinear load-deflection curve for sandwich beam with functionally graded material are presented based on refined zigzag theory (RZT). By using the variational principle, the equilibrium equations in buckling analysis are given based on the RZT formulations as well as the nonlinear strain-displacement relations. The solutions are also derived for eigenvalue problems in critical buckling load calculations and for load-deflection relations with initial geometric imperfection. The solutions are presented analytically, and the mathematical properties during the derivation process have been proven in order to keep the mathematical rigor. The present analytical RZT critical buckling loads are validated by the RZT FEM, which is the finite element solutions of the sandwich beam meshed by the beam elements based on RZT. These solutions are also compared by commercial software ANSYS, resulting that this approach can obtain an accurate critical buckling load. Various parameters such as aspect ratio, thickness ratio and modulus ratio are considered to investigate their effects on the critical buckling loads. The present results are compared to the beams with higher-order shear deformation theory (HSDT). From the comparisons of the RZT and the HSDT results, it is seen that both theories approach to CBT for slender beam. The results show that the HSDT overestimates the stiffness in the load-deflection curve. It is shown that the RZT exhibits the zigzag displacements at high accuracy, resulting in accurate calculation in critical buckling loads, mode shapes and nonlinear load-deflection curves than HSDT. The superiority of the RZT solutions is presented especially for the case of FGM sandwich beam with soft middle layer. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Computational Mechanics / Jisuan Lixue Xuebao is the property of Chinese Journal of Computational Mechanics Editorial Office, Dalian University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Laser ablation damage has an important impact on the load-bearing capacity of the aircraft structure. This paper first uses ABAQUS ALE adaptive grid technology to establish and verify the numerical simulation analysis method of laser irradiation ablation of CFRP laminates. Then a finite element simulation analysis was conducted on the buckling process of the CFRP cylindrical shell under the combined loading conditions of laser irradiation and axial compression, and the critical buckling load and buckling mode of the cylindrical shell under different conditions were obtained. The effects of ablation damage and laser irradiation position on the critical buckling load are also discussed. When the laser irradiation position is between the end and the midpoint of the axis in the axial direction of the cylindrical, and is farthest from the axis in the radial direction, buckling failure is prone to occur. [ABSTRACT FROM AUTHOR]

In order to solve the problem that U-shaped steel sheet piles (USSSPs) are prone to buckling when inserted, we propose a local stiffened U-shaped steel sheet pile destabilization critical load calculation method, namely 'dynamic alignment coefficient method', and analyze the influence of stiffening area, stiffening position and number of stiffening plates on the stiffening effect.The study shows that when the total stiffening area is certain, there is a scheme of stiffening plate arrangement to maximize the critical load value of USSSPs with determined length,and reveals the law of local instability caused by the small width of single stiffening plate when the number of blocks is too large. The critical load value of the member can be increased by 13.55% with the variation of the single stiffener plate arrangement position for 10 m long USSSPs, and the optimized theoretical scheme of stiffener plate arrangement for 10 m and 30 m long USSSPs with different total stiffener area is obtained. [ABSTRACT FROM AUTHOR]

The method of numerical integration of Euler problem of buckling of a homogeneous console with symmetrical cross section in regime of plastic deformation using Maple18 is presented. The ordinary differential equation for a transversal coordinate \(y\) was deduced which takes into consideration higher geometrical momenta of cross section area. As an argument in the equation a dimensionless console slope \(p=tg \theta\) is used which is linked in mutually unique manner with all other linear displacements. Real strain-stress diagram of metals (steel, titan) and PTFE polymers were modelled via the Maple nonlinear regression with cubic polynomial to provide a conditional yield point (\(t\),\(\sigma_f\)). The console parameters (free length \(l_0\), \(m\), cross section area \(S\) and minimal gyration moment \(J_x\)) were chosen so that a critical buckling forces \(F_\text{cr}\) corresponded to the stresses \(\sigma\) close to the yield strength \(\sigma_f\). To find the key dependence of the final slope \(p_f\) vs load \(F\) needed for the shape determination the equality for restored console length was applied. The dependences \(p_f(F)\) and shapes \(y(z)\), \(z\) being a longitudinal coordinate, were determined within these three approaches: plastic regime with cubic strain-stress diagram, tangent modulus \(E_\text{tang}\) approximations and Hook’s law. It was found that critical buckling load \(F_\text{cr}\) in plastic range nearly two times less of that for an ideal Hook’s law. A quasi-identity of calculated console shapes was found for the same final slope \(p_f\) within the three approaches especially for the metals.

This paper derives buckling solutions for single variable thick plate buckling problems using the double finite sine transform method (DFSTM). The problem governing partial differential equation (GPDE), originally formulated by Shimpi and others, uses a refined plate theory (RPT) and accounts for transverse shear deformations, rendering it applicable to thick plates. The thick plate is simply supported and subjected to (i) uniform uniaxial compressive load in the x direction. (ii) uniform biaxial compressive load in the x and y axes. The DFSTM was applied to the GPDE, and the problem transformed into an algebraic equation, which was simpler in this case due to the Dirichlet boundary conditions satisfied by the sinusoidal kernel of the DFSTM. Analytical buckling solutions were determined for the two considered cases of uniaxial and biaxial compressive loads in terms of the buckling modes, Poisson’s ratio (m), and thickness (h) to least dimension (a) ratio. Critical buckling loads (Pcr) determined at the first buckling modes agreed with previously obtained Navier solutions for Mindlin, Reddy, and Refined plates. Pcr calculated for ratios of h/a equal to 0.01 converged to the solutions obtained using Kirchhoff-Love plate theory (KLPT), illustrating the applicability of the GPDE to thin and thin plate buckling.

The straight part of the corrugated steel plate (CSP) pipe-arch structure in soil may cause local buckling instability due to insufficient load-bearing capacity. Recently, composite CSP pipe-arch has been widely utilized to enhance structural stability, and their stability needs to be thoroughly investigated. This paper studies the local buckling stability problem of the straight part of composite CSP pipe-arch in soil by simplifying the soil support and introducing the inter-layer bonding effect. Based on elastic stability theory, a theoretical mechanical model of composite CSP pipe-arch was proposed. The Rayleigh–Ritz method and the semi-combined composite structure stiffness approximation were used to derive the critical buckling conditions for the straight part of the composite CSP pipe-arch. Through numerical calculation and influencing factors analysis, it is concluded that the critical buckling load of the straight part of the composite CSP pipe-arch structure is affected by the elastic modulus, thickness, Poisson’s ratio, rotational restraint stiffness and side length of the straight part of the material. In particular, it is found that as the inter-layer bonding coefficient increases, the critical buckling load is improved, while the critical buckling wave number is mainly influenced by the width of the straight part, elastic modulus, and inter-layer bonding coefficient. Additionally, we discussed the coupling effect of several key parameters on the stability of the structure. The results of this study offer theoretical foundations and guidance for the application of composite CSP pipe-arch in soil engineering, such as culverts, tunnels, and pipeline transportation.

In underground spaces, corrugated steel plate (CSP) pipe-arches may experience local buckling instability, which can subsequently lead to the failure of the entire structure. Recently, sandwich CSP pipe-arches have been used to enhance the stability of embedded engineering outcomes, and their buckling behaviors require in-depth research. In this paper, we establish a theoretical model by simplifying soil support and using Hoff sandwich plate theory to focus on the local buckling stability of the straight segment in embedded sandwich CSP pipe-arches using the Rayleigh–Ritz method. Through stability analysis, the instability criteria for embedded sandwich CSP pipe-arches are analytically determined. Numerical calculations reveal that the critical buckling load of a sandwich CSP pipe-arch is affected by several factors, including the elastic modulus, thickness, Poisson’s ratio, rotational constraint stiffness, and the length of the straight segment. Specifically, increasing the thickness of the sandwich CSP pipe-arch can substantially enhance the critical buckling load. Meanwhile, the wavenumber is affected by the elastic modulus and the length of the straight segment. The analytical results are in agreement with those obtained from finite element analysis. These findings provide a theoretical basis and guidance for the application of sandwich CSP pipe-arches in fields such as subway stations, tunnel construction, underground passages, and underground parking facilities.

Scientists have explored alternative reinforcements to improve the mechanical properties of composite structures in recent years due to the high financial and environmental costs associated with the synthesis of carbon nanotubes and graphene plates. A sandwich composite beam reinforced with carbon nanorods (CNRRCs) synthesized from potato waste with a porous core is examined in this study. The nonlocal strain gradient theory and general strain theory are applied to this porous core structure under axially variable force. Based on the sinusoidal theory, shear deformation theory is used to calculate displacement fields of reinforced composite sandwich beams. Equilibrium sandwich beam equations are derived using higher order shear deformation theory. The mixture rule is used to determine the properties of the face sheet, including Young's modulus, shear modulus, and Poisson's ratio. A variable axial compression force is used to calculate the external work. Based on the Ritz method and different boundary conditions, the final equations are derived, and then the buckling and stiffness matrices are derived, and finally, the equations are solved and the critical buckling load is determined. An analysis of the critical buckling load for this structure is conducted using carbon nanorods made from potato waste. In addition, various parameters such as the strain gradient parameter, the non-local parameter, the volume fraction of carbon nanorods, and the thickness ratio are discussed. In this study, carbon nanorods made from recycled materials are found to increase the stiffness of sandwich beams and then increase critical buckling loads, which is lower than carbon nanotubes and more economical than carbon nanotubes. Graphene platelets and carbon nanotubes have a higher stiffness-to-cost ratio than carbon nanorods. Carbon nanorods, on the other hand, have a lower cost than graphene platelets and carbon nanotubes.

Copyright of Journal of Southeast University / Dongnan Daxue Xuebao is the property of Journal of Southeast University Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The arched cellular beam has the advantages of both the solid-web arch and the straight beam with web opening, and has become increasingly admired by architects in recent years. In this paper, four arched cellular beam specimens are designed using an orthogonal test method (OTM) with a three-factor and two-level approach. Firstly, the static loading test is carried out to analyze the mechanical response of the arched cellular beam under concentrated load. Then, a numerical analysis based on ABAQUS finite element (FE) software is carried out. The results show that the simulation results agree well with the test results, which indicates the accuracy of the simulation analysis method. Finally, the buckling load of the arched cellular beam under three different loads is calculated using the variable parameter FE analysis. Combined with the range analysis in the OTM, the influence of the target factor on the buckling load of the arched cellular beam is determined. The results show that the order of the factors affecting the out-of-plane elastic buckling is rise–span ratio > web height–thickness ratio > diameter–depth ratio. [ABSTRACT FROM AUTHOR]

The work pioneers a novel investigation into the free vibration and buckling behavior of triply periodic minimal surface beams, characterized by diverse distribution profiles. Using Euler-Bernoulli theory, under various boundary conditions, the investigation is carried out on four TPMS (Triply Periodic Minimal Surface) patterns, mainly gyroid, primitive, diamond and IWP (I-graph-wrapped package). The neutral axis would not coincide with the geometric center of the functionally graded beams so the neutral shift effect is taken into consideration appropriately. Governing differential equations are derived and the solutions are obtained numerically using the Ritz method. The mode shapes have also been calculated. It can be concluded that the type of pattern and distribution profile, boundary conditions, grade and neutral axis shift effect play a vital role in the prediction of vibration and buckling properties. [ABSTRACT FROM AUTHOR]

Sandwich plates consist of a total of three layers, with a thick core layer between two thin face layers. The face layers provide resistance to bending, while the core layer provides resistance to shear. General purpose finite element softwares are one of the most suitable and widely used analysis methods to investigate the behavior of structures. Many design parameters can be easily examined by using these analysis programs. In this study, the buckling behavior of sandwich square plates simply supported on four sides, whose ratio of core layer thickness to face layer thickness is between 7 and 9, was investigated using a general purpose finite element software. The effect of thickness variation was investigated by varying the face and core layer thicknesses of sandwich plates with a constant total thickness. At the same time, the materials of the face and core layers were changed and the most suitable design for the buckling behavior was revealed. For this purpose, 110 analyzes were made with 2 different face materials, 5 different core materials, 11 different thickness ratios. According to the results obtained from the analysis, the maximum critical buckling load was calculated as 282.108 N/mm2 in the sandwich plate with steel face and PVC H200 core. The most suitable design of sandwich plates against buckling was determined by presenting the results with graphics. [ABSTRACT FROM AUTHOR]

Double-beam systems have found many applications in civil and mechanical engineering. Extensive works of research have been conducted on the investigation of double-beam systems in which some have studied the vibration characteristics of general double-beam systems without considering the effect of axial load, whereas others investigated the vibration and buckling of axially loaded double-beam systems with classical boundary conditions. A few previous studies have considered a general axially loaded double-beam system, but none of them have provided a general solution to calculate the critical buckling load of the system with arbitrary boundary conditions. In the present study, free vibration and buckling of an axially loaded double-beam system, which was composed of two nonidentical beams with generalized boundary conditions, were analytically studied by using the Euler–Bernoulli beam theory. A semianalytical method was proposed to calculate the natural frequencies and mode shapes of the system, and an explicit formula was derived to determine the critical buckling load of the system. Parametric investigations were performed to study the influences of the connecting stiffness of the interlayer and axial loads on the dynamic characteristics and critical buckling load of the system. Results show that the proposed method can be used for free vibration and buckling analyses of generalized double-beam systems subjected to axial loads. [ABSTRACT FROM AUTHOR]

This study develops an artificial neural network (ANN) to estimate the critical buckling load (CBL) of corroded web-tapered steel I-section (WTSI) columns in pre-engineered steel buildings. A total of 387 datasets are employed to develop the ANN model. The datasets are generated from the proposed analytical model and Newton–Raphson method. The input parameters of the developed ANN model contain the cross-sectional dimensions of the steel column (i.e., the top and bottom flange width, top and bottom flange thickness, maximum section height, minimum section height, and web thickness), elastic modulus of material, and the column height. Meanwhile, the CBL is the output parameter of the ANN model. A predictive process for the CBL of the corroded WTSI columns has been proposed based on the ANN model and previous corrosion model. Results reveal that the ANN model showed an excellent performance in predicting the CBL of the corroded steel columns. The R 2 values of the training, testing, and validation data are 0.99975, 0.99916, and 0.99951, respectively. The root-mean-squared errors of the training, testing, and validation data are 96.705 kN , 103.402 kN , and 103.200 kN , respectively. Additionally, the a20-index is very close to 1.0. Moreover, a graphical user interface tool is constructed to facilitate the CBL calculation of the corroded WTSI columns. [ABSTRACT FROM AUTHOR]

The focus of this paper is to examine the static and dynamic instabilities of functionally graded beam that contains multiple inclined cracks under the influence of an axial force comprising both static and time-varying harmonic components. The elasticity modulus and mass density of the functionally graded beam are assumed to vary exponentially along its thickness direction. Local stiffness matrix model-based finite element analysis (FEA) is conducted to determine the bending stiffness and tensile stiffness of the section with a crack, and the coupled effect of tensile and bending loadings. Two-node beam elements with three degrees-of-freedom per node are utilized. By combining the Euler–Bernoulli beam theory with Lagrange method, we derive the governing equations that describe the static and dynamic instabilities of a functionally graded beam with multiple inclined cracks. These equations can be solved as eigenvalue problems to obtain the natural frequency and static critical buckling load of the beam. Furthermore, to investigate the dynamic instability of the system, we use the Bolotin method to determine the boundary between the regions of instability and stability based on the same governing equations. By adopting this approach, the study comprehensively investigates the impacts of crack position, inclination angle, and length, as well as elasticity modulus ratio, static and dynamic load factors on both static and dynamic stabilities of a cracked functionally graded beam to gain valuable insights into the stability and performance of cracked functionally graded structures. [ABSTRACT FROM AUTHOR]

Abstract Industries play a very vital role in the developed nation. Proportional to the higher production capacity of these industries, there is a surge in the quantity of waste material being discharged. This waste material can be put to effective use; a considerable way is by creating a green composite that is long-lasting, and concocted by using natural fibers and environment-friendly materials as reinforcements. In the following study, an attempt is made to investigate the buckling characteristics of a thin geometrical plate of epoxy-based composite reinforced with Sugarcane fiber/ Fly-ash/ Carbon Nanotube. The investigative study was conducted numerically on the plate by applying axially compressive load. To procure an optimized result on the weight percentages of the composition of the fiber in the composite material, the DOE/optimization tool i.e. a mathematical and statistical technique known as the Response Surface Methodology (RSM) was used. Essential geometrical modeling and the appropriate boundary conditions for the buckling analysis were carried out using the Static Structural and Eigen Buckling standalone systems in the ANSYS software. The analytical tool, Analysis of Variance (ANOVA) was utilized to investigate the influential degree of reinforcement variables on buckling characteristics present in the composite. The results reveal that the critical buckling loads escalate for higher weight percentages for carbon nanotube and fly-ash reinforcements in the composite composition. The optimized parameters obtained can be incorporated to achieve improved critical buckling load and hence many synthetic composites were replaced thus enhancing the sustainability of the environment.

Stiffened plates are common bearing components in aerospace structure design, which can bring great economic benefits and reduce the structure weight based on the insurance of the plate performance. Therefore, the lightweight design of stiffened plate structures is a research focus in the aerospace field. Based on the concept of synchronous failure, a new type of arc rib stiffened plate was proposed to sufficiently make use of the axial bearing capacity of ribs. Then, the critical buckling load of the arc rib stiffened plate was accurately predicted based on the smeared stiffener method. The lightweight design of arc rib stiffened plates was carried out by means of the particle swarm optimization algorithm. The results show that, the arc rib stiffened plate has excellent bearing capacity, significant lightweight design effects, and promising optimization results. [ABSTRACT FROM AUTHOR]

This research focuses on the buckling behavior of a porous Functionally Graded (FG) sandwich plate using the sinusoidal shear deformation theory and hyperbolic tangent and secant thickness stretching functions with novel displacement fields. The proposed model assumes a different thickness layer system with FGM on the top and bottom and a ceramic core. Hamilton's energy principle is applied to the FGM sandwich plates to understand their buckling behavior. The mesh convergence on Finite Element (FE) model is carried out, and the accuracy of the results is tested using the existing research. The present model results match reasonably well with the previously published literature. The impact of the transverse shear deformation, plate aspect ratio, size-to-thickness ratio, and volume fraction is investigated for different thickness layer systems. [ABSTRACT FROM AUTHOR]

• Accurate buckling model is proposed for hygro-thermo-magneto-electro-elastic shells. • Non-uniform pre-buckling effect is introduced to enhance the accuracy of critical buckling loads. • Both axisymmetric and non-axisymmetric buckling solutions are obtained simultaneously. • Critical buckling stresses and analytical buckling modes are obtained simultaneously. • Parametrical effects on buckling behaviors under multi-physical fields are revealed. An accurate buckling model for the magneto-electro-elastic (MEE) composite cylindrical shell under hygro-thermo-magneto-electro-elastic (HTMEE) loads is proposed by considering non-uniform pre-buckling effects. Nonlinear governing equations involving HTMEE multi-physical coupling effects are derived based on the higher-order shear deformation theory (HSDT) and von Karman geometrical nonlinearity. Critical buckling stresses and analytical buckling mode for both the axisymmetric and non-axisymmetric buckling are obtained by the Galerkin method. In numerical examples, comparisons between theoretical predictions and existing results are presented, and excellent agreements are observed. Special attention is paid to evaluation of pre-buckling effects on buckling behaviors of HTMEE shells subjected to multi-physical fields. A comprehensive parametric study is performed to reveal effects of key influencing factors on critical buckling stresses and buckling modes. It is believed that present results will be useful for assessing other numerical methodologies and contributing the rapid design of sensors and actuators with HTMEE cylindrical shells. [ABSTRACT FROM AUTHOR]

The buckling failure of the afterburner cylinder is a serious safety concern for aero-engines. To tackle this issue, the buckling simulation analysis of the afterburner cylinder was carried out by using finite element method (FEM) software to obtain the buckling mode and critical buckling loads. It was found that the afterburner cylinder was susceptible to buckling when subjected to differential pressure or the compressive force of the rear flange. Buckling would occur when the differential pressure reached 0.4 times the atmospheric pressure or when the axial compressive force on the rear flange reached 222.8 kN. Buckling was also found at the front of the cylinder under the auxiliary mount load. Additionally, under various loads on the rear flange, buckling occurred in the rear section, with the buckling mode being closely related to the load characteristics. Based on the simulation results and structural design requirements, two structural improvements were proposed, including the wall-thickening scheme and the grid reinforcement scheme. FEM simulation analysis results showed that both schemes would improve the rigidity and stability of the afterburner cylinder. For the 0.3 mm increase in the wall thickness scheme, the critical buckling load increased by 17.86% to 66.4%; for the grid reinforcement scheme, the critical buckling load increased by 169% to 619%. Therefore, the grid reinforcement scheme had a stronger anti-buckling ability and was deemed the optimal solution. The findings of this paper could provide technical support for the structural design of large-sized and thin-walled components of aero-engines. [ABSTRACT FROM AUTHOR]

An accurate nonlinear hygrothermal-electro-elastic (HTEE) buckling analysis of piezoelectric fiber-reinforced composite cylindrical shells subjected to the coupled loading effects of axial compression and hydrostatic pressure was established by considering the nonuniform prebuckling effect. Nonlinear governing equations were derived based on higher-order shear deformation theory and Novozhilov's nonlinear shell theory. Accurate critical buckling stresses and pressures and explicit buckling modes for both axisymmetric and nonaxisymmetric buckling were obtained by the Galerkin method. A comparison between the new prediction and existing results is presented and excellent agreement is reported. A comprehensive parametric study of geometric parameters, end conditions, distribution patterns, and hygrothermal-electric multiphysical fields on the buckling behavior of HTEE composite cylindrical shell is also analyzed and discussed. [ABSTRACT FROM AUTHOR]

• A novel semi-analytical method is developed for stiffened plates. • The method's base functions are the closed-form mode functions of simple plates. • The present method is suitable for all homogenous boundary conditions. • Exact solutions are obtained for simply-supported stiffened plates. Stiffened plates are widely used in various engineering fields as main load-carrying components. Semi-analytical methods are effective for studying the eigenbuckling problems of stiffened rectangular plates, but there are no semi-analytical solutions available for stiffened plates with arbitrary homogeneous boundary conditions. This work aims to develop a semi-analytical method for solving the eigenbuckling problems of orthotropic stiffened thin plates. In this method, base functions for constructing the mode functions of stiffened plate are the mode functions of a simple plate (a plate without stiffener), and the base functions are obtained with the extended separation-of-variable method, which is a closed-form solution method for the eigenvalue problems of plates. The critical buckling load is achieved by substituting the mode functions into the Rayleigh's principle. The present method can deal with arbitrary homogeneous boundary conditions without anticipating the forms of the base functions for different boundary conditions. The accuracy can be improved by using more superposition terms. Besides, an exact closed-form solution of simply supported stiffened plates is achieved, serving as benchmark solutions. Numerical experiments validate the accuracy of the present solutions, and the study on the minimum stiffener stiffness is conducted for different boundary conditions. [ABSTRACT FROM AUTHOR]

Based on CFRP(Carbon Fiber Reinforced Plastics) cylindrical pressure shell, the CFRP circumferential corrugation pressure shell is proposed in this study. The structure can further improve the buckling resistance capacity of CFRP pressure shell. Five CFRP circumferential corrugation pressure shells with varying corrugation structure parameters are designed and compared with CFRP cylindrical pressure shell. The buckling behaviors of the shells are analyzed in detail by nonlinear finite element method. The result show that reasonable corrugation structure can significantly improve the resist buckling capacity of CFRP cylindrical pressure shell. However, the increase of corrugation structure parameters will exacerbate the damage to the CFRP layers outside the pressure shell. Ultimately, pressure shell N2 with the best buckling resistance capacity is selected for hydrostatic pressure test, and the experimental results are found to align with the numerical simulation results. This study offers a novel approach for the design of deep-sea pressure shell structures. • 6 CFRP pressure shells with varying corrugation structure parameters were designed. • The impact of corrugation structure on buckling behavior of pressure shells was revealed. • Pressure shell buckling behavior can be improved by proper corrugation structure. [ABSTRACT FROM AUTHOR]

• The stability of sandwich nanobeams are interconnected via Kerr-type foundation is investigated. • The three couple equations are extracted using the Eringen's nonlocal elasticity theory. • The buckling loads are determined using the generalized differential quadrature method. • Results are discussed and the importance of some geometric and material parameters is learned. In this study, the endurable buckling load of the elastically connected parallel sandwich nano-beams with varying cross-sections is assessed. In this regard, a layered beam system consisting of two parallel axially loaded tapered sandwich nanobeams that are interconnected via a Kerr-type three-parameter elastic foundation is considered. The geometric properties are assumed to be changed exponentially along the length of the beam element. The governing equilibrium equations of the system are described by a set of three coupled homogeneous differential equations, which originates in the context of Eringen's non-local elasticity theory and Euler beam model. Then, the numerical differential quadrature technique is used to estimate the endurable axial critical loads. Eventually, a comprehensive parameterization research is performed to investigate the sensitivity of linear buckling resistance to tapering ratio, nonlocal parameter, stiffness of elastic connections, volume fraction exponent, and thickness ratio. The research work of the present study is novel, and the attained numerical outcomes can be used as benchmarks for future researches in this field. [ABSTRACT FROM AUTHOR]

The arched cellular beam has the advantages of both the solid-web arch and the straight beam with web opening, and has become increasingly admired by architects in recent years. In this paper, four arched cellular beam specimens are designed using an orthogonal test method (OTM) with a three-factor and two-level approach. Firstly, the static loading test is carried out to analyze the mechanical response of the arched cellular beam under concentrated load. Then, a numerical analysis based on ABAQUS finite element (FE) software is carried out. The results show that the simulation results agree well with the test results, which indicates the accuracy of the simulation analysis method. Finally, the buckling load of the arched cellular beam under three different loads is calculated using the variable parameter FE analysis. Combined with the range analysis in the OTM, the influence of the target factor on the buckling load of the arched cellular beam is determined. The results show that the order of the factors affecting the out-of-plane elastic buckling is rise–span ratio > web height–thickness ratio > diameter–depth ratio.

In the present research, results of buckling analysis of 384 finite element models, verified using three different test results obtained from three separate experimental investigations, were used to study the effects of five parameters such as D/t, L/D, imperfection, mesh size and mesh size ratio. Moreover, proposed equations by offshore structural standards concerning global and local buckling capacity of tubular members including former API RP 2A WSD and recent API RP 2A LRFD, ISO 19902, and NORSOK N-004 have been compared to FE and experimental results. One of the most crucial parts in the estimation of the capacity curve of offshore jacket structures is the correct modeling of compressive members to properly investigate the interaction of global and local buckling which leads to the correct estimation of performance levels and ductility. Achievement of the proper compressive behavior of tubular members validated by experimental data is the main purpose of this paper. Modeling of compressive braces of offshore jacket platforms by 3D shell or solid elements can consider buckling modes and deformations due to local buckling. ABAQUS FE software is selected for FE modeling. The scope of action of each of elastic buckling, plastic buckling, and compressive yielding for various L/r ratios is described. Furthermore, the most affected part of each parameter on the buckling capacity curve is specified. The pushover results of the Resalat Jacket with proper versus improper modeling of compressive members have been compared as a case study. According to the results, applying improper mesh size for compressive members can under-predict the ductility by 33% and under-estimate the lateral loading capacity by up to 8%. Regarding elastic stiffness and post-buckling strength, the mesh size ratio is introduced as the most effective parameter. Besides, imperfection is significantly the most important parameter in terms of critical buckling load. [ABSTRACT FROM AUTHOR]

Size-dependent functionally graded material thin plate buckling and post-buckling problems are considered using the framework of the MCST (Modified Couple Stress Theory). Based on modified couple stress theory and power law, the post-buckling deflection and critical buckling load of simply supported functionally graded material thin plate are derived using Hamilton's minimum potential energy principle. The analysis compares the simulation results of linear buckling and nonlinear buckling. Innovatively, a power-law distribution with scale effects is considered. The influences of scale effect parameters l and power-law index parameters k on buckling displacement, load, and strain energy of plates have been investigated. In this article, it is found that the critical buckling displacement, critical buckling load, and buckling strain energy increase with increases in the power-law index parameters k. The membrane energy decreases as the power-law index parameter increases. If the upper and lower layers are swapped, the opposite result is obtained. In comparison, the scale effect parameter is more influential than the power-law exponent. The critical buckling displacement in the x-direction is not affected by scale effects. The critical buckling load, the membrane energy, and buckling strain energy increase as the scale effect parameter increases. Scale effects increase material stiffness compared with traditional theory, and the power-law index parameters affect FGM properties such as elastic modulus, Poisson's ratio, density, etc. Both scale effects parameters and power-law index parameters have important effects on the mechanical behavior of materials. [ABSTRACT FROM AUTHOR]

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The performance and functionality of natural fiber reinforced polymer composites can be enhanced many folds by incorporating hard filler particulates which may significantly increase mechanical properties. This study was aimed to hybridize the jute fabric reinforced polymer (JFRP) based laminated composites with cement particulates for the enhancement of their mechanical properties. The laminated cement particulates filled jute fabric reinforced polymer (CmJFRP) and JFRP composites were fabricated via hand lay-up method. The weight fraction of cement particles was varied as 1%, 3%, and 5%. The thickness of the composites was also varied as 3.1 mm, 4.4 mm, and 6.3 mm (i.e. by varying the number of lamina). The mechanical behavior of the composites was assessed via tensile test, microhardness, Izod impact test, and critical buckling load. The tensile tests revealed that CmJFRP composites exhibit lower tensile strength than that of JFRP composites, which was mainly ascribed to the agglomeration of cement particles at the fiber/matrix interface. The microhardness, impact strength, and critical buckling load were higher for CmJFRP composites as compared to JFRP composites. The scanning electron microscopy of the fractured composites revealed that crack front changed its plane and direction when it encountered the cement particles. [ABSTRACT FROM AUTHOR]

The Euler–Bernoulli theory of beams is usually presented in two forms: (i) in the linear case of a small slope using Cartesian coordinates along and normal to the straight undeflected position; and (ii) in the non-linear case of a large slope using curvilinear coordinates along the deflected position, namely, the arc length and angle of inclination. The present paper starts with the exact equation in a third form, that is, (iii) using Cartesian coordinates along and normal to the undeflected position like (i), but allowing exactly the non-linear effects of a large slope like (ii). This third form of the equation of the elastica shows that the exact non-linear shape is a superposition of linear harmonics; thus, the non-linear effects of a large slope are equivalent to the generation of harmonics of a linear solution for a small slope. In conclusion, it is shown that: (i) the critical buckling load is the same in the linear and non-linear cases because it is determined by the fundamental mode; (ii) the buckled shape of the elastica is different in the linear and non-linear cases because non-linearity adds harmonics to the fundamental mode. The non-linear shape of the elastica, for cases when powers of the slope cannot be neglected, is illustrated for the first four buckling modes of cantilever, pinned, and clamped beams with different lengths and amplitudes.

• A novel method to extract P cr from load vs. in-plane displacement data. • Highly sensitive to slope changes while reducing adverse graph fluctuations. • Reliable results confirmed by comparison with Southwell plot and strain bifurcation. • Applicable to various column/plate structures including laminates and sandwich panels. • The method can serve as an independent and complementary approach to determine P cr. Based on the literature, the load vs. in-plane displacement diagram (P-u curve) is not sufficiently indicative to provide a reliable determination of the critical buckling load, P cr. This attitude is rooted in three issues. First, the P-u curve often exhibits very gradual slope changes, second, it concerns unavoidable graph fluctuations caused by imperfections in specimens or boundary conditions, and third, the P-u curve behavior during the buckling phenomenon is not fully understood. In the present work, a narrative review is conducted to gain a better understanding of the location of P cr on the P-u curve. Accordingly, a novel method is introduced to correctly extract P cr from the load vs. in-plane displacement diagram as the most accessible buckling test output, compared to out-of-plane displacement and strain monitoring data, which require additional equipment. The proposed method is highly sensitive to changes in the slope of the graph while significantly reducing the adverse effects of undesired fluctuations. This method is applied to several experimental buckling data for composite laminates as well as sandwich panels, and its reliability and accuracy are confirmed by comparison with other well-known methods. [Display omitted] [ABSTRACT FROM AUTHOR]