Experimental investigation of response of monolithic and bilayer plates to impulsive loads

This article presents the results of a series of experiments performed to assess the dynamic response of circular monolithic steel and steel-polyurea bilayer plates to impulsive loads. A convenient technique to enhance the energy absorption capability of steel plates and to improve their resistance to fracturing in dynamic events, is to spray-cast a layer of polyurea onto the plates. Since polyurea readily adheres to metallic surfaces and has a short curing time, the technique may be used to retrofit existing metallic structures to improve their blast resistance. We have examined the effectiveness of this approach. focusing on the question of the significance of the relative position of the polyurea layer with respect to the loading direction; i.e., we have explored whether the polyurea layer cast on the front face (the impulse-receiving face) or on the back face of the steel plate would provide a more effective blast mitigating composite. The experimental results suggest that the polyurea layer can have a significant effect on the response of the steel plate to dynamic impulsive loads, both in terms of failure mitigation and energy absorption, if it is deposited on the back face of the plate. And, remarkably, when polyurea is placed on the front face of the plate, it may actually enhance the destructive effect of the blast, promoting (rather than mitigating) the failure of the steel plate, depending on the interface bonding strength between the polyurea and steel layers. These experimental results are supported by our computational simulations of the entire experiment, employing realistic physics-based constitutive models for the steel (DH-36, in the present work) and polyurea [Amini MR, Amirkhizi AV, Nemat-Nasser S. Numerical modeling of response of monolithic and bilayer plates to impulsive loads. Int J Impact Eng, submitted for publication]. (C) 2009 Elsevier Ltd. All rights reserved.