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Buckling failure is one of the common failure modes of rock mass after the excavation and unloading of deep-buried tunnels, which brings major safety risks to the construction of deep engineering. According to the force characteristics of slabbing rock mass, it is simplified to the bending failure of rock plate under multi-directional constraints. Multi-directional constraints buckling failure tests of single-layer plates (thickness 10 mm, 20 mm) and laminated plates were carried out, and the influence of plate thickness and interlayer contact pressure on buckling failure were analyzed. The results show that the bending stiffness and ultimate bearing capacity of the rock plate are affected by the thickness of the single-layer plates and the interlayer friction of the laminated rock plates. When the lateral pressure is small, with the increase of the lateral pressure, the plasticity of the three types of rock plates increases first and then weakens. The failure mode of the single-layer rock plates gradually changes from X-shaped failure to spalling failure, while the laminated rock plate is mainly X-shaped failure. The X-shaped cracks and spalling shape of the plates are controlled by the ratio of lateral pressure. When the lateral pressure and constraints of the upper and lower plates of the laminated rock plate are consistent, the deformation of the two plates is compatible. When the lateral pressure and constraints of the two plates are inconsistent, the two plates may be delaminated. Through numerical simulation, it can be seen that with the increase of the bending degree of the plate, the force mode of the laminated plate gradually changes from point load to circle load, and the contact pressure area between the layers also changes. Highlights: Buckling failure in deep-buried tunnels is simplified to the bending of thin plate under multi-directional constraints. Strength, deformation, and failure characteristics of single-layer and laminated plates are analyzed. Mechanism of strong–weak plasticity transformation of rock plates is explained. Evolutions of the rock plates buckling failure are analyzed by endoscope. Bending characteristics of the laminated rock plates under different constraints are obtained. [ABSTRACT FROM AUTHOR]

Lattice structures are an important class of architected cellular solids and structures with high potential for multifunctional and lightweight applications. Novel technologies such as additive manufacturing have vastly extended the design freedom to develop such architectures. In this work, a reliable theoretical model for optimizing unit cell design against buckling is developed for two different cell architectures: pyramidal and tetrahedral. The model's accuracy was evaluated through extensive finite element analysis and compared to existing methods available in the literature. [ABSTRACT FROM AUTHOR]

Marine unbonded flexible pipes serve as the most essential equipment in offshore oil and gas exploration and exploitation. Axial compressive loads during installation or in service in the complex marine environment usually lead to buckling failure. A flexible pipe is a composite structure with multiple functional layers, of which the tensile armor layer plays a key role with regard to the response of the pipe subjected to axial loads. In this paper, a simplified three-dimensional finite element model is developed, focusing on the tensile layer and replacing the carcass layer, pressure sheath layer, and pressure armor layer by a cylindrical rigid body to reduce computational expense. By using this model, the buckling failure modes of the tensile armor layer (in particular the birdcaging phenomenon) are analyzed. Several key parameters that affect the stability of the flexible pipe under axial compression and torsion are emphasized, and their effects on its axial and torsional stiffness are compared and discussed. The results show that both the lay angle of the steel wires and the interlayer friction coefficient have a significant influence on the axial and torsional stiffness of the pipe, whereas the damaged length of the outer sheath has virtually no effect.

This paper presents experimental and numerical studies on compression behaviour of equal-leg steel angles with bolted connection and subjected to local defect at the bolt hole. To simulate corrosion, a mechanical cutting method was used in the experimental test to increase the diameter of bolt holes, and a total of 18 steel angles were investigated in the study. The parameters considered included the slenderness and the diameter of bolt holes. The slendernesses of steel angles were 80 and 140, and the diameter of bolt holes ranged from 21.5 to 27.5 mm. Additionally, numerical models were established for the steel angles. The accuracy of the numerical model was verified by comparing experimental data with numerical results. Based on the validated numerical model, a parametric analysis was conducted to quantitatively assess the influences of the slenderness and the diameter of bolt holes on the load capacity of specimens against global buckling. Experimental and numerical results showed that the defect at the bolt hole affected the load capacity of specimens when the diameter of the bolt hole was increased to 27.5 mm and the slenderness was not greater than 100. [ABSTRACT FROM AUTHOR]

Buckling failure of layered rock slopes due to self-weight is common in mountain areas, especially for high and steep slope, and it frequently results in serious disasters. Previous research has focused on qualitatively evaluating slope buckling stability and rarely studied the whole process from bending deformation to forming landslide. In this work, considering the tensile and compressive characteristics of rock, the simulation of high and steep slope bucking failure evolved in Bawang Mountain, was conducted by numerical manifold method. The buckling deformation mechanism and progressive failure process of Bawang Mountain high steep slope were studied. The reliability of the numerical method was verified by the comparison of theoretical calculation and field measurement data. The results show that numerical manifold method can accurately simulate high and steep slope buckling failure process by preforming interlayer and cross joints. The process of slope buckling deformation and instability failure can be divided into minor sliding-creep deformation, interlayer dislocation-slight bending, traction by slope toe-sharp uplift, accelerated sliding-landslide formation. Under the long-term action of selfweight, the evolution of slope buckling from formation to landslide is a progressive failure process, which mainly contains three stages: slight bending deformation, intense uplift deformation and landslide formation. [ABSTRACT FROM AUTHOR]

The purpose of this research is to examine the mechanism of connecting rod failure on a 110 cc 4-stroke motorcycle that exhibits plastic deformation at the connecting rod neck. Visual inspection, chemical composition testing, metallographic testing, hardness testing, and numerical simulation are the analytical techniques employed. The connecting rod material is classified as SAE-AISI 4140 steel based on the findings of the chemical composition test. The results of the metallographic tests revealed the presence of a martensite phase in the microstructure. The connecting rod material's average hardness value, as determined by the Vickers technique of hardness testing, is 500 HV. Similarity between the buckling failure mode, which happens when the load absorbed by the connecting rod exceeds the normal load and occurs in the vicinity of the maximum stress point, may be shown from stress analysis (von Mises) and buckling mode analysis (eigenvalue buckling). The history of riding motorcycles that have been altered by adding compression to get the required speed without taking the strength of the connecting rod components into account further supports this conclusion. [ABSTRACT FROM AUTHOR]

By experimental methods, 26 specimens were designed to conduct elastic and elastic–plastic buckling tests on cylindrical shells containing cracks. This study discusses the influence of factors such as the length–diameter ratio, the diameter–thickness ratio, the crack length, the inclination of the crack, etc., on the buckling load. Additionally, finite element models were established to compare with experimental results. For the PMMA cylindrical shell, the results showed that as the length–diameter ratio of the cylindrical shell increased, the buckling load first decreased and then increased. For the 6063 aluminum alloy cylindrical shell, with increasing length–diameter ratio, diameter–thickness ratio, and crack length of the cylindrical shell, the buckling load decreased accordingly. However, concerning the crack inclination, as the crack inclination increased, the buckling load increased accordingly. This indicates that the larger the crack inclination, the higher the load capacity of the cylindrical shell containing cracks. Through finite element simulations of cylindrical shells with cracks, it was found that through compressive mechanical properties, both elastic and elastic–plastic buckling loads yielded results that are closer to the experimental results. Additionally, the inclusion of contact effects in numerical simulations further improved the agreement with the experimental results, and the variation trend of the buckling load in the finite element simulation was consistent with the experimental results. The research findings provide valuable references for the assessment of load capacity in structures containing cracks. [ABSTRACT FROM AUTHOR]

In this paper, according to the characteristics of bedding slope deformation and buckling failure of slab cracked rock mass in Xinjiang Tianchi Energy South open-pit Coal Mine, with the help of slope radar monitoring means, by transforming the prediction of landslide failure process into the judgment of gradual failure of slope rock mass, the internal relationship between slope radar slope surface displacement rate and slope deformation and buckling failure is analyzed, and based on elastic plate theory, the relationship between slope buckling failure length and anchorage parameters is discussed. The results show that the radar displacement rate of slope surface shows an obvious downward trend in the strong bending uplift stage before the failure of slab cracked rock mass due to the expansion of tension cracks and the exposure of bottom sliding surface; the inflection point at which the radar displacement rate on the slope surface drops to the minimum value can be used as the graphical criterion of slope failure and the time node of critical sliding early warning; when the anchor row spacing is less than the ultimate length of slope buckling failure, the anchor bolt（cable） can effectively improve the flexural stiffness of plate cracked rock mass, and the treatment effect of plate cracked rock mass buckling failure is remarkable.

Based on the energy equilibrium, the computational formula of critical buckling length of multi-layer rock slope is derived. Considering interlayer and cross joints, the numerical manifold method is used to simulate the buckling evolution process of Malvern hills slope in New Zealand, and the theoretical calculation and numerical simulation results are compared with the field measured data. The results show that numerical manifold method can accurately simulate slope buckling failure process by preforming interlayer and cross joints. The process of slope buckling deformation and instability failure can be divided into interlayer dislocation-slight bending, slope toe traction-sharp uplift and accelerated sliding-landslide formation. Under the long-term action of self-weight, the evolution of slope buckling from formation to failure mainly includes three stages: initial bending, sharp bending and landslide formation. The angle between cross joint and slope normal is defined as β. Among the four kinds of cross joints with the angle β of 0°, 15°, 30° and 45°, the slope with 45° cross joint is most prone to slipping and bending deformation, the degree of buckling is the largest, and the number of time steps of slipping and bending is the least. When β is in the range of 30°−45°, the numerical simulation results are in good agreement with the reality.

To evaluate the performance of wheel coupler formwork support components, the bearing capacity of the horizontal bar, the shear capacity of the wheel, the shear capacity of the sleeve, and the stability bearing capacity of the single- and double-layer vertical poles were investigated through systematic full-scale tests. The feasibility and correctness of the experiment were verified by comparing the results with those of a finite element analysis. The results demonstrated that the weak point of the horizontal bar was the bearing capacity of the weld at the connection between the socket and the horizontal bar. Preventing buckling failure of the weld at the connection between the horizontal bar and the socket was critical to ensure the bearing capacity of the horizontal bar. Under the action of a shearing force, the wheel underwent buckling failure of the welding seam at the connection between the wheel and the vertical pole. With a decreasing number of connecting horizontal bars on the wheel, the shear capacity of the wheel decreased significantly. The shear failure mode of the sleeve was buckling failure. The connection weld did not undergo buckling failure during the load-bearing process, which was basically meeting the serviceability state. The failure of a single-layer vertical pole was typical with lateral displacement buckling, while the double-layer vertical pole did not undergo buckling with lateral displacement. [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]

Hat-shaped steel members are widely used in solar greenhouses, due to their low cost, fast construction, and high material efficiency. This study aims to determine the ultimate bearing capacity of a solar greenhouse with the hat-shaped steel under snow loads. The typical solar greenhouse with an 8 m span and 3.8 m ridge height was selected as the research object. The finite element method (FEM) under ANSYS software was used to analyze the instability mechanism and failure modal of the structure under snow loads (uniform and non-uniform snow loads). An investigation was made to clarify the effects of the longitudinal tie bars, initial geometric imperfections, and sectional dimensions on the ultimate bearing capacity of the structure under non-uniform snow loads. Both the material and geometrical nonlinearity were considered in the finite element model. A bilinear kinematic hardening model was adopted for the steel with a yield strength of 235 MPa, Young’s modulus of 206 GPa, and Poisson’s ratio of 0.3. The geometrical nonlinearity was activated using the ‘NLGEOM’ option. To consider the local buckling, the greenhouse skeletons were then modeled with the Shell181 element suitable for the large strains and rotations. Fixed hinge supports were used for both ends of the skeleton. An arc-length method was utilized to trace the nonlinear load-displacement curve, in order to calculate the ultimate bearing capacity of the structure under snow loads. The ultimate bearing capacity of the solar greenhouse with the hat-shaped steel was slightly higher than that of the hollow rectangular section under the same conditions of net section area, upper flange width, web depth, and wall thickness. The solar greenhouse was more sensitive to the non-uniform snow loads, compared with the uniform ones. The ultimate bearing capacity of the hat-shaped steel solar greenhouse under non-uniform snow loads was about 28% of that under uniform snow loads. Therefore, some suggestions were presented for the non-uniform snow loads in the design stage of the solar greenhouse structure. The roof ridge and north roof end were dangerous sections under non-uniform snow loads, which firstly entered the full section yield state. The longitudinal tie bars were expected to effectively improve the ultimate bearing capacity of the greenhouse structure. The ultimate bearing capacity of the structure with the longitudinal tie bars was about 1.25 times that without tie bars. The ultimate bearing capacity was only reduced by 2%, when the initial geometric imperfections amplitude increased from 5 to 20 mm. It infers that the solar greenhouse was not sensitive to the initial geometric imperfection. The cross-section size of a hat-shaped steel was recommended that the ratio of the upper flange width to the lip width, the upper flange width to the lower flange width, and the web depth to the lower flange width were about 4.17, 3.33, and 4.67, respectively, while, the ratio of the web depth to the lip width, and the lower flange width to lip width were less than 9.25 and 1.7, respectively. These findings can provide a strong reference for the solar greenhouse with the open cold-formed thin-walled steel under snow loads. [ABSTRACT FROM AUTHOR]

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The Winkler foundation model is widely used in soil calculation for the analysis of buckling failure of super-long piles. The model regards the foundation soil as an elastic body composed of discrete spring elements with the continuity of the foundation soil ignored, which is inconsistent with the actual engineering. In this paper, the double-parameter foundation model which conforms to the actual deformation characteristics of soil is introduced. The model uses two independent parameters to reflect the characteristics of the foundation soil, and the shearing effect between the soil springs is considered to reflect the continuity of foundation soil. Based on this, the total potential energy function of the pile-soil system is established. According to the principle of stationary potential energy and the variational method, the analytical solution of the buckling critical load of the pile foundation can be calculated by the m-method and the combination method respectively. The results of the example show that the error between the calculated method and the test piles is within 5%, which indicates that the double-parameter can accurately reflect the reaction behavior of the foundation soil during the buckling failure of super-long pile in the actual engineering. Meanwhile, the soil resistance model of the combination method is closer to the actual pile body constraint. [ABSTRACT FROM AUTHOR]

To evaluate the performance of wheel coupler formwork support components, the bearing capacity of the horizontal bar, the shear capacity of the wheel, the shear capacity of the sleeve, and the stability bearing capacity of the single- and double-layer vertical poles were investigated through systematic full-scale tests. The feasibility and correctness of the experiment were verified by comparing the results with those of a finite element analysis. The results demonstrated that the weak point of the horizontal bar was the bearing capacity of the weld at the connection between the socket and the horizontal bar. Preventing buckling failure of the weld at the connection between the horizontal bar and the socket was critical to ensure the bearing capacity of the horizontal bar. Under the action of a shearing force, the wheel underwent buckling failure of the welding seam at the connection between the wheel and the vertical pole. With a decreasing number of connecting horizontal bars on the wheel, the shear capacity of the wheel decreased significantly. The shear failure mode of the sleeve was buckling failure. The connection weld did not undergo buckling failure during the load-bearing process, which was basically meeting the serviceability state. The failure of a single-layer vertical pole was typical with lateral displacement buckling, while the double-layer vertical pole did not undergo buckling with lateral displacement.

• FE models were established to examine the behavior of buckling propagation and crossover. • The influences of geometry and material property of pipes and arrestors on the failure mode and crossover pressure were numerically explored. • Four machine learning models were developed to predict the failure mode, crossover pressure, and arresting efficiency, respectively. Integral buckle arrestors are regarded as the most effective arresting devices, which can provide an obstruction to a propagating buckle thereby protecting downstream pipelines. In the present study, numerical frameworks were established to reproduce the phenomenon of buckling propagating and crossing under hydrostatic pressure, and a strong consistency between measurements and predictions was achieved. The stress levels and deformation configurations of the assembly were carefully examined for two different failure modes. Then, broad parametric analyses on the crossover pressure were performed covering key material properties and geometries. After that, machine learning techniques were developed and used for predictions of failure modes, crossover pressure, and arresting efficiency, respectively. Four algorithms, including Random Forest, Multi-layer Perceptron, K-Nearest Neighbors, and Support Vector Machine, were implemented using a dataset with seven variables. The prediction performance was evaluated by standard statistical metrics, and it was found that Multi-layer Perceptron model exhibited the better prediction accuracy for both classification and regression problems. Additionally, the existing experimental results were also used to verify the reliability of the machine learning model. The results demonstrate that the machine learning techniques can offer relatively accurate predictions for both flattening and flipping failure modes. [ABSTRACT FROM AUTHOR]

In this paper, compressive behavior of tubular structures made of aluminum and multilayer carbon fiber reinforced plastic (CFRP) are studied experimentally and numerically. Results show that current evaluation of aluminum tubes using Johnson–Euler method overestimates the critical stress values of the tubular structure because local failure is ignored. A finite element analysis (FEA) model based on Riks method is proposed to re-evaluate compressive performance and failure modes of aluminum tubes. This model is modified for laminated composites by introducing damage model based on Hashin's theory, such as matrix tensile/compressive failure, and fiber tensile/compressive failure. Simulation results of CFRP tubular structure show close agreement with experimental results, but also sensitive to geometric constants. Material failure is primarily the failure mode of tubes with slenderness ratios under 21. A mixed failure mode can be found for slenderness ratios of tubes between 21 and 35. For tubes with slenderness ratios above 35, buckling failure is the primary failure mode. [Display omitted] • Establish evaluation criteria for load carrying capacity of tubular structures. • Analyze compressive behavior of tube by numerical and experimental methods. • Study the large-scale effect in metallic and composite tubular structure. • Design a new compression fixture to test composite tubular specimens. • Examine delamination of composite tubes under axial compressive load. [ABSTRACT FROM AUTHOR]

Thin-walled cylindrical shell is a fundamental engineering structure which has efficient load-carrying capacity. In practical application, this structure is more easily subjected to localized axial compression loads and is prone to buckling. However, until now there is only limited studies on the buckling problems of multi-region localized axial compression loaded cylindrical shells. To elucidate the buckling behaviors of cylindrical shell under such kind of non-uniform loading condition, experimental and numerical studies are carried out in this paper. Twenty cylindrical shell test specimens with different types of localized axial compression loads are fabricated and tested. The corresponding finite element model considering the measured initial geometric imperfections is established for buckling analysis, and good agreement between the numerical and experimental results is validated. Then the buckling failure mode and axial load-carrying capacity of cylindrical shells are investigated in details. Finally, the imperfection sensitivity of thin-walled cylindrical shell under multi-region localized axial compression is discussed. It is found that the number of loading regions and the total loading area have significant effects on buckling failure mode and axial load-carrying capacity of cylindrical shells. The results obtained from experimental and numerical studies can provide some important guidance or suggestions for the design of thin-walled cylindrical shell structures in actual engineering. • Buckling tests of 20 metallic thin-walled cylindrical shell specimens under multi-region localized axial compression loads were performed. • Finite element model for studying buckling behaviors of cylindrical shell were established. • Buckling failure mode and axial load-carrying capacity of cylindrical shell were systematically investigated for the first time. • Imperfection sensitivity of cylindrical shell under multi-region localized axial compression loads was discussed. [ABSTRACT FROM AUTHOR]

• Calculation assuming the equally long beams overestimates the load carrying capacity. • Single beam FE analysis is used to find the optimized lengths within the tolerance. • The load carrying capacity decreases for the optimized beam combination significantly. • The load carrying capacity boundaries determine the field of experimental results. The paper presents an improved algorithm to compute an axial load carrying capacity of the specific multi-beam structure in order to failure avoidance. The former approach based on the finite element method is reduced to determine a relation between the axial load and axial displacement for a single beam, while the time-consuming FE procedure applied on several beams is replaced with a numerical optimization process. The developed approach provides faster and simpler computation of the minimum axial load carrying capacity of the structure considering the beam length tolerances, where the results are in a good agreement with the complex FE analysis. Supporting theoretical and experimental analyses were performed to confirm the correctness of the mentioned method where the load carrying capacity of the multi-beam structure made up of six steel circular beams was analyzed. [ABSTRACT FROM AUTHOR]

Bimetal mechanical clad pipe is one of the main measures for anti-corrosion control adopted in oil and gas fields. The liner pipe failure is a key problem that restricting the clad pipe applications. In this paper, a calculation model of clad pipe is established, and the buckling failure of liner pipe under complex loading was investigated. Effects of forming process, working pressure, external environmental loading and structural parameters on the failure mode of liner pipe were studied. The results show that increasing the residual contact pressure in the forming process is helpful to improve the buckling resistance of the liner pipe. The residual stress between liner and outer pipes can make the clad pipes bear a larger bending loads and have a larger critical curvature. Buckling mode "8" of the liner pipe occurs under complex loading. A larger working pressure can reduce the buckling degree and fold amplitude of the liner pipe. The liner pipe is more resistant to buckling in shallow water than in deep water. With the increasing of the wall thickness for liner and outer pipes, buckling resistance of the liner pipe becomes stronger. Finally, prediction formulas for critical curvature and the maximum normalized bending moment of the clad pipe are presented. The research results can provide a theoretical basis for the design, manufacture, and safety evaluation of clad pipe. • Hydroforming process of bimetal mechanical composite pipe is studied. • Buckling mechanism of liner pipe is studied under complex loading. • Effects of forming process, structure, internal and external pressure on liner pipe failure mode are studied. • Critical curvature and maximum normalized bending moment formulas are predicted. [ABSTRACT FROM AUTHOR]