Plenary Lecture

Toward Damage Tolerance Design of Nonlinear Cracked Laminated Composite Shell Structures under Internal Pressure

Professor Cho Wing Solomon To
Co-author: Jiming Fu
Department of Mechanical and Materials Engineering
University of Nebraska
USA
E-mail: cto2@unl.edu

Abstract: Currently, the commonly adopted approach of damage tolerance design for shell structures under static or steady state internal pressure is the application of bulging factors. As pointed out in a recent paper by the authors, bulging factors available in the literature have several important shortcomings for damage tolerance design and characterization of cracked cylindrical shell structures under internal pressure. For example, the bulging factorsare hinged on stress intensity factor at the crack tip and therefore numerical results obtained by techniques such as the finite element method (FEM) are very sensitive to the mesh around the crack tip. Further, bulging factors are only applicable to isotropic cracked shell structures under internal static and steady state internal pressure. The authors have recently proposed the equivalent bulging factors for cracked laminated composite shell structures under internal dynamic pressure. While the equivalent bulging factors have potential to be applied to the damage tolerance design of nonlinear cracked laminated composite shell structures under internal dynamic pressure they still suffer the same important limitation that they are only applicable to specific ranges of ratios of crack length to diameter of the shell structures. In order to circumvent this important limitation the maximum nonlinear transversal or out-of-plane response at the center of the flange or edge of the crack is proposed as a viable alternative to damage tolerance design of laminated composite shell structures which are commonly employed in many aircrafts, and aerospace and automotive systems. Computed results for various laminated composite cylindrical shell structures under internal dynamic pressure, and their implications are included in this presentation.

Brief Biography of the Speaker: Dr. To obtained his doctoral degree in sound and vibration studies from the University of Southampton in April 1980. He is currently a professor in the Department of Mechanical Engineering at the University of Nebraska (UNL). Prior to joining UNL he was a professor (1994-96) and an associate professor (1986-94) at the University of Western Ontario. He was an associate professor (1985-86) and an assistant professor (1982-85) at the University of Calgary. Between 1982 and 1992 he was a University Research Fellow of the Natural Sciences and Engineering Research Council, Canada. He was a Research Fellow at the Institute of Sound and Vibration Research (ISVR), University of Southampton during his doctoral degree studies. After his doctoral degree studies he worked briefly in the Wolfson Unit of the ISVR on machinery noise and vibration problems of drop hammers, and vibration diagnostics in helicopters of the Royal Navy before moving to the University of Calgary. His main academic interests are in nonlinear stochastic structural dynamics, nonlinear finite element analysis with particular reference to laminated composite plates and shells, nonlinear dynamics and control, and mechanics of carbon nano-tubes.

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