Numerical Study of Non-Ideal Explosive Detonations
Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
This thesis has been carried out at BAE Systems Hägglunds, a company in Örnsköldsvik which develops and produces military vehicles. The main focus in this thesis is numerical studies of non-ideal detonations such as those which arise when using ANFO as the main explosive in a charge. ANFO is a mix of ammonium nitrate and fuel oil and often used as an improvised explosive device in terrorism activities. A non-ideal detonation means that the reaction zone is much longer than for an ideal detonation and may not be assumed to have an abrupt discontinuity. In other studies this phenomenon has shown to cause special properties, for instance a detonation velocity that depends heavily on charge radius and external confinement. In this study the purpose and aim is to show this behaviour in simulations with the finite element code LS-DYNA. The simulations were performed with cylindrical charges modelled in 2D in axi-symmetry. The explosive was modelled either by the Jones-Wilkins-Lee equation of state or by the more advanced ignition and growth reactive flow model. A comparison between the two is made and the result shows that the ignition and growth in a good way confirm the behaviour of a non-ideal detonation. The conclusions are that the ignition and growth reactive flow model seems to be an adequate method to simulate non-ideal explosives. More material parameters for ANFO would thou be needed, now it was rather limited and own assumptions had to be made in order to use the Ignition and growth model. In the future a combination of the ignition and growth model and a more advanced equation of state, such as Williamsburg, might be an even better way to describe a non-ideal detonation. The most important thou would be more experimental data to validate the simulations with ignition and growth against.
Place, publisher, year, edition, pages
2011. , 34 p.
IdentifiersURN: urn:nbn:se:ltu:diva-54768Local ID: bb2a4a43-6aa9-4f6e-8f90-82165dd9679cOAI: oai:DiVA.org:ltu-54768DiVA: diva2:1028150
Subject / course
Student thesis, at least 30 credits
Engineering Physics, master's level
Validerat; 20110526 (anonymous)2016-10-042016-10-04Bibliographically approved