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Title: Computational modelling of full aperture easy open ends for improved can end design
Author: Taylor, Daryn
Awarding Body: Swansea University
Current Institution: Swansea University
Date of Award: 2011
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Easy-Open-End`s (EOE) in can design are increasing within the can making industry, drink can EOE's known as pouring aperture's are now widely used because of their consumer friendliness. Following this trend manufacturers are developing EOE's with near full aperture opening, for use in the food can market, known as Full- Aperture-Easy-Open-Ends (FAEOE) they eliminate the need for can opening devices. FAEOE's are manufactured from metals such as aluminium and increasingly steel, all incorporate a shared design feature whereby the can end incorporates a circumferential score with integral pull-tab that enables the consumer to easily gain access by lifting the tab to initiate a fracture that then propagates around the circumferential score. For competitiveness, the steel end manufacturer needs to use a thinner gauge whilst at the same time refining the design to improve opening performance. Traditionally, end optimisation is a long-drawn- out process, but now, modern computational methods may have the potential to allow end optimisation to be modelled accurately. The damage and fracture mechanisms that lead to crack initiation and propagation in the opening process are not fully understood, therefore optimisation of easy open end scores is largely based on trial and error. This thesis presents an experimental analysis that concentrates on the combined shear and bending forces as applied to the particular industrial method concerning full aperture easy open ends, together with a computational analysis that concentrates on the simulation of score forming and the damage that accumulates as a punch is pressed into thin steel sheet. The use of damage models within simulation is steadily increasing along with having greater accuracy in tension, however, descriptions of performance in compression and shear are relatively hard to find. Damage simulation of score forming should help provide better knowledge of the mechanisms present when opening easy open ends and give additional understanding of the novel experiments that have been undertaken for dissimilar loading modes; this understanding will eventually lead to the development of a complete multi-mode model for can end optimisation. The influence of a gradually increasing gap on traditional groove geometries and depths are examined for modern packaging steels. Earlier studies have shown that the complete opening cycle depends on fracture modes I, II and III as well as their combination. Experimental results for modes I II and III will be presented, however, attention will focus on the behaviour of the initial fracture point whereby prior investigations have shown it to be influenced primarily by mode II shearing. After initial specimen manufacture, where the score is formed by pressing a punch into a thin steel sheet, the predeformed scored specimens are loaded in shear to simulate the local stress held found during the initial opening phase. Experiments have been completed using a novel mode II experimental technique that has been designed for use in the majority of commercially available tensile test machines. Experimental results indicate that opening forces can change radically with different gap sizes and that there is considerable potential for the industrialised process of can end manufacture to be optimised through the efficient management and control of the can ends dimensional parameters.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Eng.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available