The buckling of compressively-loaded members is one of the most important factors limiting the overall strength and stability of a structure. I have developed novel techniques for using active control to wiggle a structural element in such a way that buckling is prevented. I present the results of analysis, simulation, and experimentation to show that buckling can be prevented through computer-...

This paper presents a generalized formulation for the problem of buckling optimization of anisotropic, radially graded, thin-walled, long cylinders subject to external hydrostatic pressure. The main structure to be analyzed is built of multi-angle fibrous laminated composite lay-ups having different volume fractions of the constituent materials within the individual plies. This yield to a piece...

in this paper, the finite element analysis of stability problem of vehicle composite drive shafts subjected to torsional loading is studied. first, using the minimum total potential energy principle, the governing equations are derived and then they are solved by finite element method. the initial geometrical imperfection which is usually in the form of radial displacement, is taken into consid...

The purpose of this study was to evaluate the mechanical behavior of three composites with nanoparticles Filtek Z350 XT (3M ESPE), Esthet X (Dentsply), Grandio (Voco) in enamel and body shades (A2) trough nanohardness, elastic modulus, compressive strength test, flexural strength test, diametral tensile strength, flexural modulus, weight filler content and Knoop microhardness. One sample of eac...

In this study, the flexural behavior of ultra-high-performance fiber-reinforced concrete (UHPFRC) is examined as a function of fiber length and volume fraction. Straight steel fiber with three different lengths (lf) of 13, 19.5, and 30 mm and four different volume fractions (vf) of 0.5%, 1.0%, 1.5%, and 2.0% are considered. Test results show that post-cracking flexural properties of UHPFRC, suc...

Linear eigenvalue analysis of cracked cylindrical shells under combined internal pressure and axial compression is carried out to study the effect of crack type, size and orientation on the buckling behavior of cylindrical thin shells. Two types of crack are considered; through crack and thumbnail crack. Our calculations indicate that depending on the crack type, length, orientation and the int...

in this paper, simulation and analysis of thin steel cylindrical shells with elliptical cutouts under oblique loading were studied using finite element method. first, the numerical results were validated by the results of experimental test performed by an instron 8802 servo hydraulic machine. also, the effect of cutout angle (θ), cutout size, cutout position (l0/l) and cutout aspect ratios (b/a...

This paper is concerned with the inelastic behavior of axially loaded concrete-filled thin-walled steel tubular columns subjected to local buckling. A nonlinear fiber element analysis program accounting for local buckling effects is developed for predicting the ultimate strength and ductility of concrete-filled thin-walled steel tubular columns. The effects of local buckling are taken into cons...

The nonlinear mechanical response of carbon nanotubes, referred to as their "buckling" behavior, is a major topic in the nanotube research community. Buckling means a deformation process in which a large strain beyond a threshold causes an abrupt change in the strain energy vs. deformation profile. Thus far, much effort has been devoted to analysis of the buckling of nanotubes under various loa...