Advances in robust methods for limit load analysis

Fanous, Ihab F. Z. (2008) Advances in robust methods for limit load analysis. Doctoral (PhD) thesis, Memorial University of Newfoundland.

[English] PDF - Accepted Version Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission. Download (7MB)

Abstract

Limit load analysis is an essential tool in engineering analysis. Several methods were developed for both the upper and lower bound limit load multipliers. Several methods are developed with the objective of having a simplified analysis procedure to evaluate the limit load without the use of complex inelastic analysis. The recently developed lower bound solutions are either conservative or have some limitations in their applications. The redistribution node method was developed earlier as a lower bound limit load solution using the iterative elastic finite element analysis. It was applied to several two dimensional problems. -- In the present work, the iterative R-Node method is introduced as a tool to calculate the lower bound limit load of a component. The method interprets the redistribution of the stress to find the reference stress which is used to calculate the limit load. The applicability of the iterative R-Node method to complex three dimensional problems is investigated. This includes applications with three dimensional shell and solid brick elements. Single and multiple loads are also applied to. Also, the results are used to help in the stress classification of the finite element analysis results according to the American Society of Mechanical Engineers codes. -- Finally, the reference volume limit load analysis was developed in previous research using the m° upper bound solution. It was shown that it has a high convergence rate when compared to the other analysis methods. In this work, the method is redeveloped using the classical upper bound multiplier. The applicability of the method is verified for complex three dimensional geometries modeled using shell and solid elements.

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