Papers by Keyword: Buckling Behavior

Abstract: The antibacterial effects of AgNO₃ have been observed and utilized in various applications. However, only a few studies have examined its effects on the mechanical properties of a matrix when combined. In this study, AgNO₃ was used as an additive and blended with PLA resin for 3D printing to study its impact on buckling behavior, which is critical for designing slender column structures. To prepare the mixture, several processes were undertaken: (1) dissolving AgNO₃ in distilled water; (2) adding the dissolved AgNO₃ into the PLA resin; (3) stirring; (4) degassing; and (5) re-stirring. Based on the experimental results, the addition of AgNO₃ led to a decrease in the buckling strength of PLA. For pure PLA specimens, the critical buckling stresses are 47.92, 44.91, 29.72, and 17.11 MPa for lengths of 10, 50, 100, and 150 mm, respectively. For the PLA + 2% AgNO₃ specimens, the values are 23.55, 18.89, 15.1, and 10.48 MPa for the same lengths. Moreover, when compared to the theory using the Johnson and Euler buckling formulas, the obtained experimental results show good agreement.

Abstract: Axial compressive simulations are performed on defective and non-defective multiwalledcarbon nanotubes (MWCNTs) using the molecular dynamics method, and the effectof defects upon the buckling behavior is discussed. In our previous study, changes in atomicstresses in MWCNTs with three layers were evaluated until buckling occurred. That studysuggested that the transition from homogeneous stress distributions to inhomogeneous onesplays an important role in the occurrence of buckling in MWCNTs, though the critical stressesor strains relating to buckling are dependent upon the structure and location of defects. In thepresent study, the atomic elastic stiffness of each atom, Bij , is evaluated to discuss the onsetof local buckling in MWCNTs with five layers. The det(Bij) of all atoms is found to change toa negative value long before buckling occurs, while the second smallest eigenvalues of Bij forsome atoms change to a negative value just prior to buckling. The existence of dense regions ofatoms that have two negative eigenvalues of Bij are found to vary as a function of the defectlocation, and to correspond with onset points of local buckling.

Abstract: This paper presents finite element analysis on cold-formed steel-section columns with complex edge stiffeners and web holes under axial compression. A total of 18 channel models with different parameters such as length, thickness and flange width are simulated. Failure modes, the ultimate load and the stress distribution around web holes are researched. The analysis results show that, the main failure mode of-section columns with complex edge stiffeners and web holes is distortional buckling. The carrying efficiency is higher as the thickness-width ratio increasing. Because of perforations on the web, the position of the max stress changes from the web near the mid-height of the specimens to the location adjacent to holes.

Abstract: In the present work the stability and buckling behavior of compressed beams on elastic foundation are analyzed. The influence of the elastic stiffness of the medium on the overall stability of the structural system is investigated. The analysis is performed via energetic methods. The buckling loads are evaluated as a function of the stiffness of the beam and the stiffness of the elastic medium. Considerations are illustrated on the influence of the elastic medium stiffness and on the effects of the ratio of the length of the beam and the characteristic half-wave on the stability of the structural system.

Abstract: The discovery of buckling instability and vibration of polyethylene/ carbon nanotube matrices is reported by molecular mechanics simulations. The research is aimed to acquire a high strength design of PE-CNT matrix with proper PE/CNT ratio as well as discovering the dynamic characteristics of the PE-CNT composites. The buckling strains and the resonance frequencies are found to decrease with an increase in the number of polyethylene chains in the polyethylene/carbon nanotube matrices. Van der Waals forces are collected to explain the relation of the PE chains to the buckling strain and the resonance frequency of the composites.

Abstract: Due to the development in the construction and building industry in recent years, numerous methods for safer, easier and more economical design of structures have been studied.Because of the high bi-axial bending capacity and high compressive strength of hollow structural sections, these sections are considered as a popular alternative by designers. Supporting the panel zone demands in the columns and occurring the moment hinge at the ends of beam are too available in column with hollow section. One of the major problems in the way of using these sections is lack of appropriate load path to connect beams to them, which ends up using through-plates. Through-plates are plates that pass through column and beams connect to them at their webs. Consequently these plates should have sufficient stiffness in order to provide enough strength. This paper proceeds to study the buckling behavior of through-plates in moment beam to column connections under gravity loads.

Abstract: The purpose of this study is to assess the effect of van der Waals interactions within multi-walled carbon nanotubes with the three dimensional finite element models. The elastic buckling behaviors of nanotubes are treated under axial compressive force acting on open both ends of nanotubes and considered with various boundary conditions. The analysis is based on the assumptions that the covalent bond of each wall is represented by an elastic beam element while the van der Waals force of adjacent walls are represented by a nonlinear truss element following the Lennard-Jones “6-12” theory. The models of double-walled carbon nanotubes are used to explain the characteristic of multi-walled carbon nanotubes and then results compared with the column theory. The results show that the critical load of nanotubes depends on atomic arrangement, tube length, and number of walls, while the van der Waals force has a small effect on the buckling load for multi-walled carbon nanotubes.