Professor C. A. Steeves University of Toronto Institute for Aerospace Studies 4925 Dufferin St., Toronto, Ontario, Canada M3H 5T6 Phone:      +1-416-667-7710 Fax:          +1-416-667-7799      Email:      csteeves (at_sign) utias.utoronto.ca Web:        Multifunctional Structures Lab

Craig A Steeves is an assistant professor at UTIAS. Dr Steeves has both a Bachelor of Arts degree in International Relations from Trinity College, University of Toronto and a Bachelor of Applied Science in Civil Engineering from the University of British Columbia. He received his Doctor of Philosophy in 2002 from the Cambridge University Engineering Department, studying composite mechanics in Prof Norman Fleck's Micromechanics Group. In particular, this work focused on minimum-weight design of composite structures. Subsequently Dr Steeves joined the Applied Physics Group of the Princeton University Department of Mechanical and Aerospace Engineering where he worked with Prof Richard Miles on the use of multifunctional sandwich structures in the context of magnetohydrodynamic power generation on reentering space vehicles. Finally, Dr Steeves worked with Prof Tony Evans at the Materials Department of the University of California, Santa Barbara on topics related to airbreathing hypersonic flight.

The Multifunctional Structures Research Group conducts research efforts in the area of enhanced aerospace vehicle performance through the integration of novel functional elements into structural components. This work revolves around combining mechanical models of thermostructural behaviour with models of other physical phenomena in order to achieve optimal designs of aerospace structures in a multidimensional and multidisciplinary design space. The goal is to create component-level designs for aerospace applications which integrate multiple functions in a lightweight, low volume package. Combining structural and functional elements into a single multifunctional component package reduces the weight and volume of the vehicle while increasing performance. Examples of integrated multifunctional structures are magnetohydrodynamic power systems on re-entering spacecraft, structural leading edge heat pipes on hypersonic airbreathers and morphing aerodynamic systems. Functionally enhanced structures enable vehicles which are more efficient, effective and environmentally friendly.

Recent work has been on materials and structures for use on hypersonic airbreathing vehicles. Thermal protection was a significant issue, and two approaches were studied, one using stiff low thermal expansion bimaterial lattices for acreage thermal protection, and a second employing heat pipes integrated into metallic structures for thermal protection at the leading edge. Another project in the same program led to the design and construction of a morphing supersonic wind tunnel to demonstrate the uses of shape-adaptive structures for shock control at scramjet engine cowl lips and in the combustor.

Two projects which are beginning are related to sandwich panels with periodic cellular cores. Sandwiches of this sort offer significant opportunities for weight savings, and, in addition, the open core structure allows the insertion of additional functional elements. The complex core structures can also be tailored to meet other non-structural requirements. These projects are, first, an examination of defects, damage and damage propagation in cellular core sandwiches. The use of such structures in critical aerospace applications necessitates a detailed understanding of how the materials behave, degrade and survive in challenging environments. A second project is to determine how the overall properties of the sandwich panel can be customised by adding, removing or modifying some of the cell in the core. These projects are, in a sense, inverses of each other, as both examine the effects of small geometrical or other changes on the macroscopic behaviour of the structure.