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Copyright of Journal of National University of Defense Technology / Guofang Keji Daxue Xuebao is the property of NUDT Press 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.)

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.)

In order to study the buckling behavior and post‑buckling behavior of stiffened panels with different opening sizes in aircraft structures under compression load, the corresponding test method and test fixture are designed and the compression test of the panels is completed. The buckling/failure loads, instability processes and failure modes of stiffened panels with different opening sizes are obtained. The results show that the buckling mode of the stiffened panel is the opposite deformation of the interbar skin and the outer skin, and the buckling mode changes several times with the increase of load. The compressive failure mode of stiffened panel is based on the buckling deformation with obvious deformation. The finite element simulation for stiffened panels with different opening sizes is carried out. The buckling and failure modes obtained are consistent with the experimental results. The error of buckling/failure load and test results is less than 4%, which verifies the validity of the finite element model. The simulation results show that with the increase of the opening size, the yield load of the stiffened panel decreases slowly at first and then increases rapidly, the failure load of the panel decreases gradually, and finally the structure loses the post‑buckling bearing capacity. [ABSTRACT FROM AUTHOR]

Based on the nonlocal theory, a ID layered nano-quasicrystal (QC) simply supported beam model was established to investigate the free vibration, buckling behavior, and bending deformation of nano-QC beams. The pseudo-Stroh formula was used to derive the governing equations for the nanobeam. Using the transfer matrix method, exact solutions of the natural frequency, the critical buckling load, the generalized dis- placement and the generalized stress for bending problems of layered nano-QC beams was obtained under sim- ply supported boundary conditions. The effects of the height-span ratio, the layer thickness ratio, the stacking sequence, and the nonlocal effect on the natural frequency, the critical buckling load and the bending deformation of layered nano-QC simply supported beams were analyzed. The results show that, the natural frequency and the critical buckling load decrease with increasing nonlocal parameter. The bigger the outer-layer quasicrystal elastic constant is, the higher the natural frequency and the buckling critical load will be. The stacking sequence has a significant effect on the mechanical behavior of nano-QC beams. The obtained exact solution pro- vides a reference for various numerical methods and experimental results of nanoscale beam structures. [ABSTRACT FROM AUTHOR]

In the field mechanical setting procedure, the selection of the wellhead slack-off weight is now primarily based on experience. For deep horizontal wells, conservative empirical parameters can damage the packer, which has a significant impact on the setting effect and well test safety. Therefore, a string loading model of a deep horizontal well under mechanical setting was established, based on the principle of mechanical setting and fully considering the influence of wellbore trajectory, buckling friction of string, and variable cross-section of string, combined with the three-dimensional soft rod model. In the field, the model was used to construct the wellhead hanging weight release value of a deep horizontal well. The difference between the computation findings and the field measurement is 7%, indicating that the model is reliable. The parameter sensitivity analysis reveals that the main reasons affecting the axial load of the test string are the wellbore trajectory friction and buckling friction. The increase in the tubing-to-casing radial clearance and the effective axial compression load will aggravate the buckling. Severe buckling will lock the test string, so that the released wellhead hanging weight cannot be effectively transmitted. The position of the packer determines the friction caused by the wellbore trajectory in the setting stage. The closer the position is to the bottom of the well, the more the string friction and buckling friction will increase, ultimately reducing the setting efficiency. [ABSTRACT FROM AUTHOR]

Based on the symplectic superposition method (SSM) pioneered by the authors, the buckling problem of typical non-Lévy-type orthotropic cylindrical shells was solved analytically, which is difficult to handle with conventional analytical methods. The Hamiltonian system-based governing equations for buckling of orthotropic cylindrical shells were firstly established based on Donnell’s shell theory. The original problem under non-Lévy-type boundary conditions was then divided into 2 subproblems, and each subproblem was solved with the mathematical techniques incorporating separation of variables and symplectic eigen expansion within the Hamiltonian framework. The analytical solution of the original problem was finally given through the superposition of the sub-solutions to satisfy the boundary conditions of the original problem. The numerical examples under consideration show that, the SSM-based analytical solutions are in good agreement with the finite element results. In addition, the effects of parameters including the length and the thickness on the critical buckling loads were quantitatively studied. Compared with the conventional analytical methods such as the semi-inverse method, the SSM works based on rigorous mathematical derivation without any assumption of the solution forms, and can obtain reliable analytical solutions to more similar issues. [ABSTRACT FROM AUTHOR]

Copyright of Acta Materiae Compositae Sinica is the property of Acta Materiea Compositae Sinica Editorial Department 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.)

Copyright of Engineering Mechanics / Gongcheng Lixue is the property of Engineering Mechanics Editorial Department 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.)

Cutouts are widely used in ships and offshore structures, which are used mainly for inspection, and they may be fitted for other purposes, such as passing pipes and reducing weight. In general, the existence of cutouts can reduce the structural strength, so the plates with cutouts（perforated plates） are given high importance at the structural design stage. In this regard, locally reinforced perforated plates are often used in shipyards to satisfy the structural buckling and ultimate strength requirements, but quantitative evaluations of the reinforced perforated plates have a little insufficient. To mitigate the reduction of the structural strength, flanged cutout has been adopted as a reinforcing method to achieve the structural buckling and ultimate strength increase, but no standard methodologies or recommendations are available for the cutout parameters of this stiffener. In this paper, a series of numerical studies were undertaken to analyze the buckling and ultimate strengths of different thickness flanged-perforated plates, for various cutout parameters（cutout radius, flanging length and flanging angle） under edge shear loading condition. The results can provide references for the design of flanged-cutouts in engineering.

Copyright of Journal of Northeast Petroleum University is the property of Journal of Northeast Petroleum 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.)

Copyright of Engineering Mechanics / Gongcheng Lixue is the property of Engineering Mechanics Editorial Department 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.)

Copyright of Chinese Journal of Applied Mechanics is the property of Chinese Journal of Applied Mechanics 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.)

Copyright of Engineering Mechanics / Gongcheng Lixue is the property of Engineering Mechanics Editorial Department 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.)

Copyright of Engineering Mechanics / Gongcheng Lixue is the property of Engineering Mechanics Editorial Department 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.)

Copyright of Acta Materiae Compositae Sinica is the property of Acta Materiea Compositae Sinica Editorial Department 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.)

Copyright of Journal of Engineering for Thermal Energy & Power / Reneng Dongli Gongcheng is the property of Journal of Engineering for Thermal Energy & Power 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.)

Copyright of Acta Materiae Compositae Sinica is the property of Acta Materiea Compositae Sinica Editorial Department 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.)

Finite strip method (FSM) is a classical method to analyze the buckling of thin-walled members. The traditional FSM adopting trigonometric functions longitudinally can hardly analyze the members with spaced ribs along the longitudinal direction, while the compound strip method (CSM) can compensate for this shortcoming. Based on the CSM, the influence of utilizing plane elements and shell elements to respectively imitate stiffeners on buckling is investigated. Compared with the shell-element ribs, the plane-element ribs are prone to assembling the stiffener matrices with fewer degrees of freedom. But the shell-element ribs are more comprehensive as the out-plane displacement of ribs are taken into consideration. It is found that plane element ribs and shell element ribs have little difference on the buckling capacity of members. The buckling capacity has a small difference of mean absolute error (MAE) underneath 0.75% between the two types of CSMs, and the buckling capacity and modes are in good agreement with the finite element results. The buckling loads of the two types of CSMs are close to the FEM with a MEA less than 5%. The accuracy of the plane elements satisfies the predicted requirements, which helps to reduce the program computation and simplify the analysis complexity. The efficiency of analysis can be dramatically improved for fine meshing elements.

In order to study the effect of buckling of tubing on the properties of special threads in high temperature and high production wells. A three-dimensional finite element model of a special thread was established with the help of ABAQUS finite element software. Combined with the actual buckling conditions, and comprehensively consider factors such as temperature, internal pressure and axial force. The stress distribution of the special thread of the tubing after buckling and the contact pressure distribution on the sealing structure were obtained. The results show that after the tubing is buckled, the stress distribution on the special threaded ring is uneven. It is manifested that the Von Mises stress and contact pressure on the compressed side are significantly greater than those on the tensile side. And the stress concentration in the joint ring is more prominent in the sinusoidal buckling section than in the helical buckling section. After buckling, the Von Mises stress value of the shoulder on the compression side and the first buckle of the external thread of the large end of the pipe body exceeds the yield strength of the material, and the structure undergoes plastic deformation. The contact pressure on the sealing surface on the tension side and on the shoulder surface is zero, and the sealing structure loses its sealing ability. [ABSTRACT FROM AUTHOR]

Aiming at the buckling instability of the CRTS II slab ballastless track under temperature load, a nonlinear buckling finite element model is established based on the finite element software Abaqus, which considers the initial irregularities and the friction behavior between the track plates, and the arc length method is used to track the thermal buckling nonlinearity. The nonlinear path is analyzed by parameterization of the influencing factors such as irregularity amplitude, friction performance, track weight and track stiffness. The research results show that the magnitude of the initial irregularity affects whether there is an unstable phase in the nonlinear path of the track structure; sudden buckling will occur when the initial irregularity amplitude of the track structure is 5 mm, and it will not occur when the irregularity amplitude is 50 mm; the friction performance between the track plate and the CA mortar has almost no influence on the critical temperature, the initial branches of the equilibrium path are almost the same, the post-buckling stage tends to diverge, and the safety temperature has a greater influence; the increase of the weight of track structure significantly inhibits the upper arch buckling of the track structure, the increase of the deadweight of track structure by 0.2 times may result in the increase of critical temperature by 10 °C, and the safe temperature by nearly 20 °C; the increase in track stiffness does not significantly improve the buckling resistance of the track structure. [ABSTRACT FROM AUTHOR]

Copyright of Acta Materiae Compositae Sinica is the property of Acta Materiea Compositae Sinica Editorial Department 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.)

Copyright of Engineering Mechanics / Gongcheng Lixue is the property of Engineering Mechanics Editorial Department 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.)

In order to study the influence of different operating modes on the dynamic response and stability of offshore wind turbines under turbulent wind and earthquake, DTU 10 MW offshore single-pile wind turbine was used as the research object. The p-y curve was used to describe the interaction between the pile foundation and the subsea soil. Based on the finite element software ANSYS, the finite element model of the wind turbine was established and the structure modal, dynamics and buckling calculation of the wind turbine were carried out. The results show that the vibration mode of the tower is dominated by torsional and bending vibration. Its first natural frequency is within the ideal design range and the rotation of the wind wheel will not cause its resonance. Turbulent wind has the most significant influence on the displacement of tower top and earthquake has much greater influence on the lateral displacement of tower top than the turbulent wind. After the earthquake, the equivalent stress and strain energy response of the tower have surged. The emergency shut-down can effectively reduce the peak of the tower top displacement, the tower equivalent stress and the tower strain energy response and reduce the risk of structural damage and plastic deformation. Under the action of turbulent wind and earthquake, lateral buckling failure will occur in the middle and upper part of the leeward surface of the tower. The emergency shut-down can effectively improve its buckling resistance and the maximum increase of critical buckling load is nearly 27.11%.

Stiffened plates is a common structural form in aviation structure. Different types of stiffened plates and different manufacturing processes will affect its mechanical behavior and failure mode. The finite element method is used to establish numerical models of titanium alloy stiffened plates, and to study the effects of the T, L and Z type stiffened plates on buckling mode and failure. The influence of manufacturing processes such as welded, spot welded, riveted and integral panels on buckling and post buckling properties are analyzed. It is shown that the buckling load and the failure load of the T-type stiffened plate are the maximum one. Different manufacturing processes have great influence on the failure load and post-buckling load capacity, among which the post-buckling load capacity of welded stiffened plate is the largest one. At the same time, the most effective stiffening method of 600 mm×600 mm stiffened plate structure is given.

In recent years " machine substitution" has become an important direction of garment manufacturing upgrading. The demand for research and development of garment production robots or production equipment to replace labor has increased and intelligent or unmanned production mode is becoming the direction of joint efforts of the garment industry. For example cloth-cutting machines are used to cut dozens of layers of fabric at a time which greatly improves the efficiency of fabrics cutting. However the cutting pieces must be manually picked layer by layer off the pile of fabric pieces before the process of sewing which is necessary to inspect the quality of a piece and to avoid color difference among pieces. Automatically separating the fabric layer-by-layer is one of the key steps which decides whether the garment manipulation is entirely automatic or not. But fabric is a kind of material that is flexible and easy to be deformed and its deformation is difficult to predict so there remains a big challenge to automatically pick up a fabric piece from a pile of cutting pieces with high accuracy. How to realize the layer-by-layer separation of cutting pieces by mechanical structure has always been the focus and difficulty in the field of automatic manufacturing and relevant scholars and researchers have made continuous research and exploration. As a robot end-effector the soft manipulator shows good flexibility and adaptability in the process of grasping the fabric which provides a new solution for the garment production automation. However the factors that affect the grasping accuracy are still unclear in the process of grasping fabric with soft manipulator which makes the adjustment of grasping parameters pressure exerted by grasping mechanism and initial finger's opening width of the manipulator blind. After preliminary experiments it is found that the buckling height of the fabric is a key factor determining whether it can be separated layer by layer in the process of grasping the fabric by the soft manipulator. The manipulator can hold the buckling part of the fabric and lift it accordingly. In order to further clarify the influence of yarn elastic modulus pressure exerted by grasping mechanism and initial finger's opening width of the manipulator on fabric buckling and improve the grasping accuracy this paper takes plain fabric as an example and establishes a 3D microscopic model of fabric and a manipulator end model. Then we import the 3D model into ABAQUS a finite element analysis software input the material parameters and generate mesh. Finally the job is submitted to simulate the buckling morphology of fabric under different grasping parameters. Meanwhile the soft manipulator is used to grasp three different styles of plain fabrics and the layering accuracy is recorded and analyzed under different grasping parameters to verify the validity of the finite element model. The results of finite element analysis show that the greater the yarn elastic modulus the less likely the fabric is to buckle. With the increase of the pressure on the first layer of fabric the maximum buckling height of the fabric increases rapidly at first and then tends to be mild. This is mainly due to the mutual restricting of multiple layers of fabrics in the grasping process and it is not appropriate to abstract a piece of fabric and analyze its force situation. The deformation length of fabric between two fingers increases with the increase of initial finger's opening width so the fabric is more prone to buckling and the maximum buckling height of the fabric increases. According to the experimental data the maximum buckling height of fabric increases with the increase of pressure exerted by grasping mechanism and initial finger's opening width within a certain range. This means that the accuracy of layer-by-layer separation can be improved by increasing the pressure on the fabric or increasing the initial finger's opening width of the soft manipulator. By simulating and analyzing the buckling of plain fabric during layer-by-layer separation the relationship between the buckling height and the elastic modulus of yarn the pressure exerted by the grasping mechanism the initial finger's opening width and other factors is obtained and the validity of the finite element analysis is verified by experiments. Such research results can provide guidance for the adjustment of grasping parameters when the soft manipulator grasps the fabric layer by layer. Meanwhile the research results can also be used to guide the structural design of soft manipulator for fabric grasping. [ABSTRACT FROM AUTHOR]

To accurately solve the buckling instability problem of a rectangular plate with free boundaries on the opposite edges, the finite difference method, FDM, was introduced. The buckling differential equations and boundary conditions equations ignoring the shear effect were discretized by the FDM; the buckling instability problem was transformed into a prob-lem of solving the generalized eigenvalues of the deflection coefficient matrix. At the same time, the opposite simply supported edges subjected to unidirectional pressure were chosen as the case study,the accuracy of the FDM results and the finite element method results were verified by comparing them with the previous results. The effect of the plate thickness on critical buckling load is difficult to measure for the moderately thick plates. Therefore, a fit-ting formula was obtained to give the applicable range of geometric parameters for the FDM within a given relative error range. Finally, the effect of geometrical parameters on the critical buckling load was analyzed. And the results show that the FDM used in this paper can solve the buckling instability problem of the rectangular plate with two opposite free edges accu-rately within the geometrical parameters range given by the fitting formula,which provides a new solution to the buckling instability problem both for the thin plates and moderately thick plates. [ABSTRACT FROM AUTHOR]

A Mindlin plate theory for micro-nano structures was proposed based on the couple stress theory. A length parameter was introduced to consider the size effect, and the constitutive equations for the micro-nano Mindlin plate were derived in view of the transverse shear deformation. The buckling and free vibration governing equations in terms of displacements and the slope functions of the shear deformation micro-nano plate were further deduced with the force equilibrium conditions. The analytical solutions of buckling and free vibration for the shear deformation micro-nano plate were obtained through separation of the displacement and rotation variables in space and time domains. Two scenarios of boundary conditions were analyzed: SSSS (simply supported by 4 edges) and SCSC (2 opposite edges simply supported and other 2 edges clamped). A MATLAB program was developed to compute the critical buckling and natural frequencies with different values of dimensional parameters, aspect ratios and length-to-thickness ratios. The research results, in comparison with those from the ABAQUS finite element analysis and previous literatures, are consistent with the latter ones. The examples show that, the size effects significantly influence the buckling load and the natural frequency. [ABSTRACT FROM AUTHOR]

Copyright of Power Generation Technology is the property of Power Generation Technology 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.)

Copyright of Journal of Shanghai Jiao Tong University (1006-2467) is the property of Journal of Shanghai Jiao Tong 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.)

Copyright of Engineering Mechanics / Gongcheng Lixue is the property of Engineering Mechanics Editorial Department 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 properties of functionally gradient materials (FGM) are closely related to porosity, which has effect on FGM's elastic modulus, Poisson's ratio, density, etc. Based on the classical theory of thin plates and Hamilton principle, the mathematical model of free vibration and buckling of FGM porous rectangular plates with compression on four sides is established. Then the dimensionless form of the governing differential equation is also obtained. The dimensionless governing differential equation and its boundary conditions are transformed by differential transformation method (DTM). After iterative convergence, the dimensionless natural frequencies and critical buckling loads of the FGM porous rectangular plate are obtained. The problem is reduced to the free vibration of FGM rectangular plate with zero porosity and compared with its exact solution. It is found that DTM gives high accuracy result. The validity of the method is verified in solving the free vibration and buckling problems of the porous FGM rectangular plates with compression on four sides. The results show that the elastic modulus of FGM porous rectangular plate decreases with the increase of gradient index and porosity. Furthermore, the effects of gradient index and porosity on dimensionless natural frequencies and critical buckling loads are further analyzed under different boundary conditions with constant aspect ratio, and the effects of aspect ratio and load on dimensionless natural frequencies under different boundary conditions.

Copyright of Acta Materiae Compositae Sinica is the property of Acta Materiea Compositae Sinica Editorial Department 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.)

Copyright of Acta Materiae Compositae Sinica is the property of Acta Materiea Compositae Sinica Editorial Department 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 main failure mode of composite stiffened panel is buckling. In order to ensure the safety of the structure and effectively reduce the weight of the structure, it is necessary to systematically study the boundary conditions and the width of the load-bearing edge of the skin when checking the buckling. Through the study of two kinds of boundary conditions and three kinds of skin load edge width selection, a method of skin load edge width selection considering the influence of stringer is put forward to calculate the buckling of stiffened panel and verify with the test results. The research results show that the engineering buckling calculation method with the boundary conditions of four sides simply supported and the width of the loading edge of the skin considering the influence of the stringer has the highest accuracy, the minimum deviation between the calculation results and the test results is 0.29%, the maximum deviation is 7.16%, and all of them are lower than the test values. It is safe and reliable to use this method to check the strength and stability of structures.

Objectives A rectangular plate buckling study is of great theoretical and practical importance. To study the axial compression buckling behavior of the rectangular plate structure commonly used in engineering under arbitrary elastic boundary conditions, we present a method for calculating buckling loads caused by elastic instability based on the minimum potential principle. Methods Rotating restrained springs and lateral restrained springs are respectively arranged on the four boundaries of the plate model. The geometric expression of the displacement function is established based on the improved Fourier series method（IFSM）. The derivative function of the displacement function on the plate boundaries may have discontinuous issues, which can be solved by introducing auxiliary functions on the basis of the classical Fourier series. The potential energy function of the rectangular plate system is established, and by using the minimum potential energy method, the linear equations of the unknown Fourier coefficient are obtained, then the buckling characteristic parameters such as the critical load of the rectangular plate are solved.Results The reasonable values of spring stiffness under different boundary conditions are given, and the obtained results are consistent with the exact solution and finite element software. The method is proved to be correct and convergent. Conclusions The contents of this paper have a certain reference value for the related structural analysis of ships.

The buckling behaviors of 2D structures with periodic elliptical holes were studied through numerical simulations and theoretical analysis. A theoretical model was established for the modal analysis corresponding to different buckling modes. The analysis results indicate that, there is a transformation between the buckling modes of the 2D structure with elliptical holes, with the change of the geometrical parameters of the holes. The theoretical analysis and the numerical results match up. Furthermore, in the numerical simulation, a modified force boundary condition for a unit cell under negative pressure activation, being different from the displacement loading, should be considered to ensure the completeness conditions are fulfilled. The confusion in the application of appropriate boundary conditions for the unit cell will result in errors. The choice of the unit cell and the derivation of correct boundary conditions, combined with finite structures, were discussed. [ABSTRACT FROM AUTHOR]

The buckling analysis of natural fiber reinforced (NFRC) cylindrical shells was performed based on Reissner’s shell theory and the symplectic approach. The governing buckling equations for axially-compressed NFRC cylindrical shells were established in the Hamiltonian system. Therefore, the original problem was reduced to a symplectic eigenproblem in the symplectic space. Accurate critical loads and analytical buckling mode shapes were directly obtained from the symplectic eigenvalues and eigensolutions. With numerical examples, the effects of hygroscopic aging on the expressions of eigensolutions were investigated. In addition, the influences of the aging time, the fiber content and the geometric parameters on the buckling behavior of NFRC cylindrical shells were discussed in detail. [ABSTRACT FROM AUTHOR]

Copyright of Acta Materiae Compositae Sinica is the property of Acta Materiea Compositae Sinica Editorial Department 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.)

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.)

Aeronautical composite stiffened panels are widely used in aeronautical structure design because of their good mechanical properties. In this paper，the compressive buckling and post-buckling mechanical properties of aeronautical composite stiffened panels were studied. Firstly，the compressive stability of composite stiffened panels was calculated by engineering method，and the predictions of the buckling and failure loads of stiffened panels were obtained；Secondly，the compression stability experiment of the composite stiffened plate is carried out，and the buckling and failure modes，the load-strain and load displacement relationship of the experimental piece，and the buckling and failure loads of the experimental piece are obtained. The results show that the calculated results by engineering method are in good agreement with the test results，and the error of buckling load and failure load are 6.12% and 9.31% respectively. The reasonable application of engineering method can provide better guidance for the experiment；The failure modes of stiffened panels are the delamination of the panels，the bulging and tearing of the skin，the fracture of the stiffeners and the debonding of the stiffeners-panels. The buckling ratio of composite stiffened plates is 1.65，the composite stiffened plates have strong post-buckling bearing capacity；The post-buckling bearing capacity of stiffened plates can be fully applied in engineering to improve the utilization efficiency of structures.

To determine the effects of shot peening on stiffened panel compressive strength,a typical shot peening residual stress was introduced by ABAQUS subroutine. Then,using temperature field equivalent method to transfer residual stress distribution to temperature boundary conditions. The local buckling and post-buckling characteristics of stiffened panels with different residual stress peak value and residual compressive stress depth are calculated respectively. The results show that,the influence coefficient of shot peening relate to the peak value of residual stress and the range of compressive stress depth. A simple determination method for influence coefficient of shot peening is given and the functions in engineering are amended. In the end,the residual stress distribution of a group of test specimens were obtained through shot peening simulation,the accuracy of amended method was verified by comparison of compression tests of shot specimens and unshot specimens.

The thin film composite often buckles due to mismatch strain between each layer induced by in-plane residual stress during manufacturing or service loadings in operation. The buckling behavior of a composite structure consisting of a thin film and a compliant substrate was studied by elastic stability analysis based on complex function theory. The buckling parameters under uniaxial and biaxial in-plane compression were calculated respectively utilizing an author compiled program. The result indicates the critical pre-buckling stress is an inherent characteristic determined by material and geometric parameters. Under uniaxial and non-equal biaxial compression stress,the critical pre-buckling stress decreases with the increase of film/substrate elastic modulus ratio,meanwhile there is only one nonzero buckling wave number in the direction of the plane. For the equal biaxial stress,the influence factors of critical pre-buckling stress and dimensionless wavelength depend on substrate/film thickness ratio. Any buckling mode that satisfied with the wave number equation could occur.

Copyright of Journal of Zhengzhou University: Engineering Science is the property of Editorial Office of Journal of Zhengzhou University: Engineering Science 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.)

Copyright of Chinese Journal of High Pressure Physics is the property of Chinese Journal of High Pressure Physics 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.)

Copyright of Journal of Engineering for Thermal Energy & Power / Reneng Dongli Gongcheng is the property of Journal of Engineering for Thermal Energy & Power 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.)

This paper presents a finite-element approach to simulate the buckling process of the composite laminated plate containing a buried delamination. The delaminated composite laminates are analyzed using solid elements. In order to prevent the mutual penetration between the two parts above and below the delamination and to ensure coordinated deformation, a normal behavior of hard contact is applied at the interfaces of the delamination to take into consideration of the nonlinear contact effect between the debonded regions. Parametric analyses are conducted to investigate the effects of delamination depth, delamination length and aspect ratio on the buckling loads. Furthermore, buckling of a perfect laminate with the same geometrical parameters is simulated to obtain the critical buckling load. A comparison between the finite element prediction and the classic theoretical solution for the perfect laminate is carried out. It is found that they are in good agreement. The established model can simulate the buckling process of the composite laminated plate accurately.

Pressure pipes have broad applications in aviation, space flight, mechanical engineering, industrial and civil architecture etc. Instability destruction is their main failure mode. Firstly, in this paper, a complex fluid-solid coupling problem was simplified as a buckling problem of a pipe under two stresses which were along the pipe wall. The two stresses consisted of a compressive stress which was perpendicular to the pipe wall and a tangential stress which was parallel to the pipe wall. Secondly, the buckling performs of the pressured pipe were discussed by finite element analysis method under a working state and an off-working state, respectively. Some obtained conclusions were drawn as follows by the analysis in this paper.1). Provided the tangential stress is unchanged, by increasing compressive stress eigenvalue buckling critical load increases and nonlinear buckling critical load decreases.2). Provided the compressive stress is unchanged, when the direction of the tangential stress is same as that of the axial pressure, by increasing the absolute value of tangential stress the buckling critical load decreases; provided the compressive stress is unchanged, when the direction of the tangential stress is in the opposite direction of the axial pressure, by increasing the absolute value of tangential stress the buckling critical load increases.

The bending and buckling of functionally graded nanoplates in intelligent devices (e.g., nanorobots) were studied based on the nonlocal strain gradient theory. The motion equations in general cases were derived, and then reduced to bending and buckling in special cases. The effects of the nonlocal scale parameter, the material characteristic scale parameter, the gradient index and the geometric size on the bending deflection and the critical buckling load were acquired and analyzed in detail. The results show that, the maximum bending deflections under different higher-order continuum mechanics theories increase with the gradient index. The deflection goes lower for the square nanoplate. The thicker the nanoplate is, the smaller the bending deflection will be. The maximum deflection increases with the nonlocal scale parameter but decreases with the material characteristic scale parameter. The critical buckling load decreases with the gradient index, and increases with the thickness and the aspect ratio. When the nonlocal scale parameter increases, the critical buckling load will decrease, but will increase with the material characteristic scale parameter. The softening and hardening mechanisms exist in higher-order bending and buckling of the functionally graded nanoplates, and the coupling effect between 2 internal characteristic parameters also occurs. When the nonlocal scale is greater than the material characteristic scale, the nonlocal effect will dominate in the mechanical properties of functionally graded nanoplates, otherwise the strain gradient effect will play a leading role. The analytical solutions also show that, when the nonlocal scale is equal to the material characteristic scale, the results based on the nonlocal strain gradient theory will degenerate into the corresponding classical ones. [ABSTRACT FROM AUTHOR]

The buckling of composite laminate plates was analyzed with the nth-order shear deformation theory. The virtual work principle was used to derive the governing equations for the critical buckling of laminate pates under in-plane loads. The comparison between the present results and the results of previous literatures shows good agreement and high calculation accuracy. [ABSTRACT FROM AUTHOR]

It is well known that the fuselage and wing mainly consist of thin-skin stiffened panels and the failure load of stiffened panels is hot topic in aircraft engineering. Johnson-Euler equation is used to evaluate the failure loads, thus the effective width computation of skin needs to be determined. Several kinds of methods to calculate the effective width of skin are analyzed to quest for its origin, and their applicability is verified with test results of thin-skin stiffened panel. The results show that, the calculation errors of the effective width calculation methods are less than 10% for the calculation of riveting Z-typed fuselage stiffened panel failure load, and the methods can be helpful to engineers who design thin-skin stiffened panels in compression.