Finite element analysis of ISO tank containers

ISO tank containers have evolved by trial and error. This is primarily due to a lack of definitive methods to analyse the strength and stiffness of the tank and frame. This has resulted in a myriad of patents of different designs, which are then tested statically to accepted standards. The primary area of concern is the attachment of the tank to the frame as this does not lend itself to analysis using traditional mechanics. Recently it has also been proposed that a standard crash test should be carried out before a new or changed design can be certified. Currently crash testing takes place in some countries and varies in method and severity. Fatigue and vibration analysis is left to the manufacturer, which often means excessively strengthened sections and little or no analysis. This project aims to model the container tank statically and dynamically for road, rail and sea conditions, using finite element methods. This paper will concern itself with modelling of the tank and frame and subsequent static FE analysis using ANSYS 5.4. The central aims of the project are: to identify the areas of high stress in the tank and support structure; to quantify these stresses; to evaluate current safety factors; to produce a more efficient and safer design; to conform to evolving certification regulations which require finite element analysis (FEA). The paper will discuss the following aspects of the project: Static modelling and verification of the model using static load data and data gathered from failed tanks in the field. Vibration and resonance analysis, currently most tank failures occur while travelling by rail, it is thought that this is primarily due to vibration.