Computational Technology Resources - CCP

Keywords: micro-polar continuum, experimental validation, truss.

Summary

Large space structures are generally too large to be field tested. It is possible to test the individual components of these structures [1,2,3]. Once the physical parameters are tested, it is desirable to build a model of the system made of these components. Hence, modelling becomes a key in predicting the structural behaviour. One such approach is the finite element analysis which requires a significant amount of storage capacity and runtime to obtain solutions for large structures; it may also produce more modes of vibration than are required [4]. On the contrary, continuum modelling has proved reliable to provide insight into the behaviour of structures with much less computational time. In this regard, a difficulty pertaining to finding equivalent continuum models for deployable structures occurs because of the joints between the inflatable members (not pinned or rigid joints that have been investigated in the previous research). There are some existing articles in the literature for rigid joints, [5,6,7] and grids [8,9]. An experimental effort for a truss based on the assumptions of hinge connections, [10], revealed the need for an alternative modelling. We develop a technique to find a micro-polar continuum model for a truss with flexible joints. Necessary assumptions are made to reduce the order of strain variables while retaining the effects of micro-rotations coupled to primary strain terms. The experimental frequencies are found and the results for both the ordinary and the micro-polar continuum model are compared. The results are improved significantly for the micro-polar continuum model compared to the ordinary continuum model.

References

1: P.A. Tarazaga, D.J. Inman, W.K. Wilkie, "Control of Space Rigidizable-Inflatable Boom Using Macro-Fiber Composite", Journal of Vibration and Control, 13(7), 935-950, 2007. doi:10.1177/1077546307078757
2: R.S. Papa, J.O. Lassiter, B.P. Ross, "Structural Dynamics Experimental Activities in Ultralightweight and Inflatable Space Structures", AIAA Journal of Spacecraft and Rockets, 40(1), 15-23, 2003. doi:10.2514/2.3934
3: K. Guidanean, G.T. Williams, "An Inflatable Rigidizable Truss Structure with Complex Joints", Proceedings of the AIAA/ASME/SAE 39th Structures, Structural Dynamics and Materials Conference, Long Beach, California, 2797-2806, 1998.
4: C.T. Sun, S.W. Liebbe, "Global-Local Approach to Solving Vibration of Large Truss Structures", AIAA Journal, 28(2), 303-308, 1990. doi:10.2514/3.10389
5: S.E. Lamberson, "Equivalent continuum finite element modelling of plate-like space lattice structures", Air Force Institute of Tech. Wright-Patterson AFB OH., Doctoral Thesis, 1985.
6: A.K. Noor, M.P. Nemeth, "Analysis of Spatial Beamlike Lattices with Rigid Joints", Computer Methods in Applied Mechanics and Engineering, 24(1), 35-59, 1980. doi:10.1016/0045-7825(80)90039-0
7: A.K. Noor, M.P. Nemeth, "Micropolar Beam Models for Lattice Grids with Rigid Joints", Computer Methods in Applied Mechanics and Engineering, 21(2), 249-263, 1980. doi:10.1016/0045-7825(80)90034-1
8: A.K. Noor, W.C. Russell, "Anisotropic Continuum Models for Beamlike Lattice Trusses", Computer Methods in Applied Mechanics & Engineering, 57(3), 257-277, 1986. doi:10.1016/0045-7825(86)90141-6
9: C.T. Sun, T.Y. Yang, "A Continuum Approach toward Dynamics of Grid Works", Journal of Applied Mechanics, 40(1), 186-192, 1973.
10: A. Salehian, D.J. Inman, "Dynamic Analysis of a Lattice Structure by Homogenization: Experimental Validation", Journal of Sound and Vibration, in press.

purchase the full-text of this paper (price £20)

go to the previous paper
go to the next paper
return to the table of contents
return to the book description
purchase this book (price £145 +P&P)

	Computational & Technology Resources an online resource for computational, engineering & technology publications
	not logged in - login
Front Page Browse CCP CSETS CTR IJRT Other Authors Search Purchase Guide FAQ Contact us	Civil-Comp Proceedings ISSN 1759-3433 CCP: 88 PROCEEDINGS OF THE NINTH INTERNATIONAL CONFERENCE ON COMPUTATIONAL STRUCTURES TECHNOLOGY Edited by: B.H.V. Topping and M. Papadrakakis Paper 93 Micro-polar Continuum Modelling of a Lattice Structure: Theory and Experiment A. Salehian¹ and D.J. Inman² ¹Department of Mechanical and Mechatronics Engineering, University of Waterloo, Ontario, Canada ²Centre for Intelligent Material Systems and Structures, Department of Mechanical Engineering, Virginia Polytechnic Institute and State University, Blacksburg VA, United States of America doi:10.4203/ccp.88.93 purchase the full-text of this paper Full Bibliographic Reference for this paper A. Salehian, D.J. Inman, "Micro-polar Continuum Modelling of a Lattice Structure: Theory and Experiment", in B.H.V. Topping, M. Papadrakakis, (Editors), "Proceedings of the Ninth International Conference on Computational Structures Technology", Civil-Comp Press, Stirlingshire, UK, Paper 93, 2008. doi:10.4203/ccp.88.93 Keywords: micro-polar continuum, experimental validation, truss. Summary Large space structures are generally too large to be field tested. It is possible to test the individual components of these structures [1,2,3]. Once the physical parameters are tested, it is desirable to build a model of the system made of these components. Hence, modelling becomes a key in predicting the structural behaviour. One such approach is the finite element analysis which requires a significant amount of storage capacity and runtime to obtain solutions for large structures; it may also produce more modes of vibration than are required [4]. On the contrary, continuum modelling has proved reliable to provide insight into the behaviour of structures with much less computational time. In this regard, a difficulty pertaining to finding equivalent continuum models for deployable structures occurs because of the joints between the inflatable members (not pinned or rigid joints that have been investigated in the previous research). There are some existing articles in the literature for rigid joints, [5,6,7] and grids [8,9]. An experimental effort for a truss based on the assumptions of hinge connections, [10], revealed the need for an alternative modelling. We develop a technique to find a micro-polar continuum model for a truss with flexible joints. Necessary assumptions are made to reduce the order of strain variables while retaining the effects of micro-rotations coupled to primary strain terms. The experimental frequencies are found and the results for both the ordinary and the micro-polar continuum model are compared. The results are improved significantly for the micro-polar continuum model compared to the ordinary continuum model. References 1 P.A. Tarazaga, D.J. Inman, W.K. Wilkie, "Control of Space Rigidizable-Inflatable Boom Using Macro-Fiber Composite", Journal of Vibration and Control, 13(7), 935-950, 2007. doi:10.1177/1077546307078757 2 R.S. Papa, J.O. Lassiter, B.P. Ross, "Structural Dynamics Experimental Activities in Ultralightweight and Inflatable Space Structures", AIAA Journal of Spacecraft and Rockets, 40(1), 15-23, 2003. doi:10.2514/2.3934 3 K. Guidanean, G.T. Williams, "An Inflatable Rigidizable Truss Structure with Complex Joints", Proceedings of the AIAA/ASME/SAE 39th Structures, Structural Dynamics and Materials Conference, Long Beach, California, 2797-2806, 1998. 4 C.T. Sun, S.W. Liebbe, "Global-Local Approach to Solving Vibration of Large Truss Structures", AIAA Journal, 28(2), 303-308, 1990. doi:10.2514/3.10389 5 S.E. Lamberson, "Equivalent continuum finite element modelling of plate-like space lattice structures", Air Force Institute of Tech. Wright-Patterson AFB OH., Doctoral Thesis, 1985. 6 A.K. Noor, M.P. Nemeth, "Analysis of Spatial Beamlike Lattices with Rigid Joints", Computer Methods in Applied Mechanics and Engineering, 24(1), 35-59, 1980. doi:10.1016/0045-7825(80)90039-0 7 A.K. Noor, M.P. Nemeth, "Micropolar Beam Models for Lattice Grids with Rigid Joints", Computer Methods in Applied Mechanics and Engineering, 21(2), 249-263, 1980. doi:10.1016/0045-7825(80)90034-1 8 A.K. Noor, W.C. Russell, "Anisotropic Continuum Models for Beamlike Lattice Trusses", Computer Methods in Applied Mechanics & Engineering, 57(3), 257-277, 1986. doi:10.1016/0045-7825(86)90141-6 9 C.T. Sun, T.Y. Yang, "A Continuum Approach toward Dynamics of Grid Works", Journal of Applied Mechanics, 40(1), 186-192, 1973. 10 A. Salehian, D.J. Inman, "Dynamic Analysis of a Lattice Structure by Homogenization: Experimental Validation", Journal of Sound and Vibration, in press. purchase the full-text of this paper (price £20) go to the previous paper go to the next paper return to the table of contents return to the book description purchase this book (price £145 +P&P)
Back to top	©Civil-Comp Limited 2023 - terms & conditions