Dynamic Analysis of the Effect of an Air Blast Wave on Plate

Abstract

Blast analysis is gaining importance as terrorist activities are increasing all around with more devastating tools and techniques. The September 11, 2001 attack on World Trade Centre towers in New York, Murrah Federal office building in Oklahoma city on 19th April 1995 showed different strategies used by terrorist for destruction. The plates are having wide range of applications in structural systems. The plates are used as infill panels to enhance catenary action in framing systems, protective systems for malls or any commercial places. In the present study, the effect of blast loading is analyzed on a square super austhenitic stainless steel (AL-6XN) plate of side 300 mm with 6 mm thickness. The dynamic analysis is performed using the Abaqus explicit finite element program. The modeling of the blast is done using the blast modeling software CONWEP (Conventional Weapons Effects), which is an empirical based loading model within finite element programs. The property of the blast load is specified using the incident wave interaction property and the CONWEP charge property at the model level and the incident wave interaction at the step level. The different weight charges are used for the analysis as equivalent TNT. The Johnson-Cook [1] flow stress model exhibits elasto-plastic behavior to calculate deformation due to the impulse loading produced by the explosive detonation. The different weight charges used for the analysis were in the range of 1.5–5 kg TNT. The maximum displacement of charge weights were in the range of 25–103 mm for strain rate independent model and 75–450 mm for strain rate effect. From results it is observed that the plate deformation is characterized into permanent or elastic deformation. Also it is observed that there is increase in stress level in strain rate dependent model than strain rate independent model.