Linear Buckling Analysis Considering No-compression Property of Metal Grid Shells Stiffened by Tension Braces

In order to analyze the buckling behavior of lattice shells stiffened by cables or slender braces without pre-tension, it is necessary to consider the no-compression property of braces. This paper proposes an innovative method of linear buckling analysis that considers the no-compression property of braces. Moreover, in order to examine the proposed method's validity, its results are compared with the results from a nonlinear buckling analysis with geometrical nonlinearity and material nonlinearity to express the no-compression property of braces. The results show that the proposed method can well-predict the buckling behaviors of lattice shells stiffened by tension braces.

Design Optimization and Non-Linear Buckling Analysis of Spherical Composite Submersible Pressure Hull

This paper describes an optimization study of a spherical composite submersible pressure hull employing a genetic algorithm (GA) in ANSYS. A total of five lay-up arrangements were optimized for three unidirectional composites carbon/epoxy, glass/epoxy, and boron/epoxy. The minimization of the buoyancy factor ( B . F ) was selected as the design optimization objective. The Tsai-Wu and Tsai-Hill failure criteria and buckling strength factor ( λ ) were used as the material failure and instability constraints. To determine the effect of geometric non-linearity and imperfections on the optimized design, a non-linear buckling analysis was also carried out for one selected optimized design in ABAQUS. The non-linear buckling analysis was carried out using the modified RIKS procedure, in which the imperfection size changed from 1 to 10 mm. A maximum decrease of 65.937% in buoyancy factor ( B . F ) over an equivalent spherical steel pressure hull was computed for carbon/epoxy. Moreover, carbon/epoxy displayed larger decreases in buoyancy factor ( B . F ) in the case of 4 out of a total of 5 lay-up arrangements. The collapse depth decreased from 517.95 m to 412.596 m for a 5 mm lowest mode imperfection. Similarly, the collapse depth decreased from 522.39 m to 315.6018 for a 5 mm worst mode imperfection.

Prediction of Nominal Compressive Strength in Steel Piles Subject to Corrosion Losses: A Finite Element Approach

This paper presents a method for predicting the nominal compressive strength of steel I-shaped piles subject to cross-sectional losses caused by corrosion. The method requires a finite element linear buckling analysis of the corroded cross-section. Results from the finite element buckling analysis may be integrated into design capacity equations contained in the 15th edition of the American Institute of Steel Construction Steel Construction Manual. Non-linear post-buckling analyses were used to verify the accuracy of the proposed method. Three cross-sectional geometries (W14x82, W14x90, and W14x120) were analyzed at varying degrees of cross-sectional loss. Results show close agreement between the non-linear finite element analyses and the proposed method of calculating nominal compressive strength.

Linear Buckling Analysis of Landing Gear

In an aircraft the landing gear is the most critical system which acts as suspension during landing and take-off. During this, it experiences very large magnitude of impact load which is mostly compressive in nature. Hence, a major concern in this structure is buckling failure. Buckling is a mode of failure in which compressive forces act along the axis of the component. Buckling can cause catastrophic deformation of the component for slight increase in load acting on the body. Many a time buckling is the deciding factor for allowable stress. So, the buckling strength of the material used for landing gear should be sufficiently high enough to resist failure. Good corrosion resistance and low density makes Ti-6Al-4V (also called TC4) the most commonly used material for the landing gear. This paper deals with linear buckling analysis of landing gear and compares the result of three titanium alloys (TC4, Ti-7Al-4Mo, TIMETAL 834) for landing gear. The landing gear assembly is designed in CREO 3.0 and linear buckling analysis is performed in ANSYS 19.2