Maritime improvised explosive devices, modelling and large scale trials

Maritime Improvised Explosive Devices (MIEDs) such as small boats filled with explosives are likely to be a threat in future combat scenarios. For example the suicide attack against the USS Cole in Yemen (October 2000) has shown how disastrous MIEDs can be. With relatively simple means a complete compartment of a ship can be flooded, with significant damage to structure and equipment and many sailors killed. Therefore measures to avoid early flooding must be researched and included in future designs. Further advice towards harbour protection measures must be formulated to the crew. Modelling the explosion phenomena and the response of the ship’s structure is the main and first step for taking effective measures. This research interest is addressed in a research program financed by the Royal Netherlands Navy and the UK DE&S. In addition cooperation was sought and found also with Germany, WTD71. First findings of the research will be addressed. These findings include: (1) modelling of explosion phenomena, (2) simulation response of a large scale test specimen representing a part of a naval ship hull structure and (3) results of large scale trials. For fast evaluation of series of attack scenarios a simplified loading model was developed. The response of a typical ship hull was calculated with this simplified loading model included in Finite Element simulations. The results correctly predicted hull deformations, moment of rupture and failure of the ship hull. Performance of this simplified loading model was evaluated against a more advanced and costly Euler-Lagrangian approach, with water and air included. Details of both types of modelling will be presented. The large scale trials include the testing of ship-like hull test specimens in a test pond in Spadeadam. These trials were done in close cooperation with DE&S Bristol and Weidlinger in 2012. To obtain FLOATEX conditions with the explosives located at the water surface, during the tests the specimens were partly sank down to investigate the effects of water and air. The response of the test specimen and the damage observed will be discussed. Further a comparison of test results and modelling will be presented.