Some aspects of research in structural dynamics and aeroelasticity at City University London Seminar
- Time:
- 12:00 - 13:00
- Date:
- 20 February 2014
- Venue:
- Seminar room 2001, Building 28
Event details
An FSI group seminar
Abstract:
Some aspects of research in structural dynamics and aeroelasticity at City University London are highlighted in this seminar. The presentation is in two parts. The first part covers dynamic stiffness formulation and free vibration analysis of structures made of both isotropic and anisotropic materials which include beams, plates, shells and their assemblies whereas the second part focuses on the aeroelasticity of metallic and composite wings which include sailplane, trainer and transport airliner aircraft. The accuracy and computational efficiency of the dynamic stiffness method, often called an exact method, in free vibration analysis are demonstrated by numerical results. The dynamic stiffness method has general applicability like the finite element method, but has much better model accuracy. Thus it can handle complex structures by assembling element stiffness matrices and yet retaining the exactness of results. Illustrative examples for free vibration of beams include tapered, twisted, rotating, spinning, moving, sandwich and functionally graded beams. In particular, the analysis of bending-torsion coupled beams is given due recognition because of their aeronautical applications. For composite beams, the effects of ply orientation and stacking sequence on the modal characteristics reveal some interesting and intriguing features which have been investigated and examined in detail. When dealing with the free vibration analysis of isotropic and anisotropic plates and shells using the dynamic stiffness method, both first order and higher order shear deformation theories have been taken into account. Layer-wise theory has also been used when developing the dynamic stiffness method for plates. Numerical results showing natural frequencies and mode shapes are given for a wide range of problems. The next sets of results are presented for the flutter behaviour of a number of high aspect ratio wings ranging from that of a sailplane to a medium to long range transport airliner with metallic construction. The final set of results focuses on the aeroelasticity of composite wings. The flutter and divergence speeds of composite wings showing the effects of wash-in and wash-out as a result of ply orientation and stacking sequence are demonstrated. The research has revealed that it is possible to alleviate or even eliminate undesirable aeroelastic phenomena like flutter and divergence. The fibrous nature of advanced composite materials provides significant opportunities to the design engineers to distribute strengths and stiffnesses and produce or manipulate desirable aeroelastic effects which hitherto had not been possible using conventional isotropic materials. The usefulness and potential of symbolic computation as a tool in structural engineering research using the dynamic stiffness method, particularly for future optimisation studies, are emphasized.
Speaker information
Professor Ranjan Banerjee , School of Engineering and Mathematical Sciences, City University London. After receiving his Bachelor's and Master's Degree in Mechanical Engineering from the University of Calcutta and the Indian Institute of Technology, Kharagpur, respectively, Ranjan Banerjee joined the Structural Engineering Division of the Indian Space Research Organisation, Trivandrum in 1971 and worked there for four years, first as a Structural Engineer and then as a Senior Structural Engineer. He was involved in the dynamic analysis of multistage solid propellant rocket structures using the finite element method. He also carried out research on the response of rocket structures to acoustic loads. Later in the year 1975 he was awarded a Commonwealth Scholarship to study for a PhD degree at Cranfield University where he conducted research within the technical areas of structural dynamics and aeroelasticity. He received his PhD in 1978. An important spin-off from his PhD was the development of an aeroelastic package in Fortran, called CALFUN (CALculation of Flutter speed Using Normal modes) which was originally written for metallic aircraft, but later extended to composite aircraft. CALFUN has been extensively used as a teaching and research tool in aeroelastic studies. After completing his PhD, he joined the Structural Engineering Division of the University of Cardiff in 1979 and worked there for six years first as a Research Associate and then as a Senior Research Associate to investigate the free vibration and buckling characteristics of space structures using the dynamic stiffness method. During this period he worked in close collaboration with NASA, Langley Research Center, and he was principally involved in the development of the well-established computer program BUNVIS (BUckling or Natural VIbration of Space Frames) which was later used by NASA and other organizations to analyse spacecraft structures. He joined City University London in 1985 as a Lecturer in Aircraft Structures and he was promoted to Senior Lecturer and Reader in 1994 and 1998 respectively. In March 2003 he was promoted to a Personal Chair in Structural Dynamics. His main research interests include dynamic stiffness formulation, aeroelasticity, unsteady aerodynamics, composite structures, functionally graded materials, aircraft design, symbolic computation, free vibration and buckling analysis of structures and associate problems of elastodynamics. He has been responsible for various research contracts as Principal Investigator, involving EPSRC, American Air Force Base, Embraer Aircraft Company, amongst others. To date he has published 95 journal papers and 76 conference papers from his research. He serves in the Editorial Boards of a number of international journals and established conferences and he has been a member of the EPSRC Peer Review College since its inception. He teaches the subjects of mechanics, strength of materials, aircraft structures, composite materials, computational structural mechanics and aeroelasticity, and he has acted as external examiner in four British universities for their undergraduate and postgraduate programmes in aeronautical engineering.