Case study

Assessment of explosion on a train

The challenge

The threat to major public transport systems, including rail and aircraft, is on the increase. Structural damage caused by an explosion inside a vehicle can be catastrophic, as well as causing serious and potentially fatal injuries to the passengers within. To develop protection systems that might mitigate the effects of such an attack, our client needed to assess the potential damage likely to occur following an explosion. Frazer-Nash was appointed to conduct a detailed analysis of an internal blast within a train carriage, and simulate the conditions during an explosion. The aim was to produce essential data that could predict the level of structural damage sustained by the vehicle

Our solution

Explicit calculation of the development and propagation of blast pressure following an explosion within a structure can be a challenge due to the complexity and resolution of the model required. Our first priority for this work was to therefore establish an efficient process of determining the impact of an explosion on the vehicle structure without the need for a lengthy and computationally expensive coupled blast analysis. We began by building a computer model of the train structure using the analysis code ‘ABAQUS’ (see figure 1). Blast pressures were then derived for each element, based on the charge mass and location of particular interest. The ABAQUS model was then used to calculate the response of the vehicle to the blast loading, predicting significant levels of deformation and structural failure (see figure 1). The predictions made using the model compare well to historic evidence from explosions on vehicles similar to the scenario examined during this work.

Benefits

Our modelling process provided our client with a detailed prediction of the explosion effects, including the levels of deformation and structural failure within the vehicle. As a result, they are now able to use the results from this analysis to develop a more robust vehicle design, or other design considerations which may mitigate the damage sustained by an internal blast. Our research has shown that the impact of an internal explosion could be accurately predicted without the need for lengthy and computationally expensive blast propagation models. This is because the calculation of blast pressure propagation and surrounding air would have had little impact on the results obtained for the scenario examined. As a result, our clients were able to study the structural impact of the blast more quickly and efficiently.

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Figure 1: The simulated effects of an explosion inside a train structure

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