A simple coupling of ALE domain with empirical blast load function in LS-DYNA

Abstract

Blast effects on structures are of great interest both in the civilian and military domain. This fact leads to the need of the development of simple and efficient simulation methods. The two common and most used methods have a very different philosophy. The first one is the construction of a full Eulerian domain containing both the detonating charge and the sollicitated structure. An inconvenience of this method is the very long duration of the simulation since the entire external domain is modelled, especially if the charge-structure distance is very large. The second method is the direct application of the corresponding loading based on empirical data (from ConWep) to the structure without simulating the external domain. Although this method allows a consequent time benefit, it has also some disadvantages such as the fact that shadowing, ground reflection and side effects are not taken into account. Moreover, every structure is considered as rigid since the load directly applied is the reflected pressure from ConWep’s database, which gives only the reflected pressure in a rigid case. This can be a problem for the application of blast loading on elastic, low-impedance materials such as granular materials or even on small density structures that are able to have a non-negligible displacement during the positive phase duration of the loading. Material impedance and structure displacement might alter the shockwave-structure interaction. A new method using both philosophies has been developed by Slavik [2]. In this method, an Arbitrary Lagrangian-Eulerian mesh (ALE) is created only around the structure in which the empirical incident pressure is applied. The loading is applied onto the air domain, propagates to the structure and interacts with this structure. At this time, the material parameters of the structure and its displacement are taken into account. This paper aims to evaluate third method’s capabilities. Moreover, it studies the influence of structure parameters on the loading by a comparison of reflected pressure and impulse.