Computational Technology Resources - CCP

Keywords: composite materials, adaptive, optimisation, finite element, experiment.

Summary

Shape-adaptive structures have applications in a number of fields for example the INCOMPRO (Intelligent Composite Products) project [1] designed and produced shape-adaptive structures as diverse as yacht booms, marine propellers, floor panels and pump impellers. The particular field of application of interest to the authors is flexible composite marine propellers.

The paper presents a design method for shape-adaptive structures that seeks to determine, by the use of an optimisation technique, the composite lay-up and unloaded structural shape such that a structure will deform into a series of desired shapes at specified loading or operating conditions. Two or more target shapes and their loads are the starting point and the unloaded structure shape and composite material lay-up is the output of the optimisation procedure. The objective of the optimisation is to minimise the distance between the predicted unloaded shapes calculated from the various target shapes by adjusting the composite lay-up. The method is based on the design of deformation method of Kress and Ermanni [2].

Experiments were conducted on composite point-loaded cantilever specimens designed to produce coupled bend-twist behaviour. Loads, deflections and strains were measured during the tests and substantial deformations were observed. Results from these experiments were used to validate some aspects of the shape-adaptive design method. Two of the measured conditions of specimen load and loaded shape were taken as target shapes and used as input to the optimisation and the unloaded shape and composite lay-up were the output. The predicted unloaded shape and lay-up were compared with those of the actual specimen.

The results of the validation exercise are disappointing. Relatively small deficiencies in the ability of the finite element model to predict deformations (3 to 4%) resulted in large differences (~30%) in the predicted ply proportions at different angles. That said, differences in stiffness, determined by comparing terms of the bending elastic modulus matrix, were much smaller (~13% maximum).

It was concluded that the quality of the predictions from the structural model, for example the finite element model, is critical to the accurate analysis and design of shape-adaptive structures. In particular, the determination of material properties is important with care required to ensure that the make-up of the material test samples, e.g. fibre volume fraction, closely matches that of the plies in the finished structure.

References

1: A. Kamoulakos, "INtelligent COMposite PROducts", Final Report submitted to the European Community (Project BE-98-5505, Contract BRPR-CT98-9006), October, 2002.
2: G. Kress, P. Ermanni, "Design of Deformation: Concept, Algorithms, and Sample Calculations", Proc Int. IMS Project Forum, Monte Verità, Ascona, Switzerland, October 6-9, 2001.

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 6 Optimisation of Composite Adaptive Response with Experimental Validation N.L. Mulcahy¹, G. Prusty² and C.P. Gardiner³ ¹Pacific Engineering Systems International, Broadway, Australia ²School of Mechanical & Manufacturing Engineering, University of New South Wales, Kensington, Australia ³Maritime Platforms Division, Defence Science and Technology Organisation, Melbourne, Australia doi:10.4203/ccp.88.6 purchase the full-text of this paper Full Bibliographic Reference for this paper N.L. Mulcahy, G. Prusty, C.P. Gardiner, "Optimisation of Composite Adaptive Response with Experimental Validation", in B.H.V. Topping, M. Papadrakakis, (Editors), "Proceedings of the Ninth International Conference on Computational Structures Technology", Civil-Comp Press, Stirlingshire, UK, Paper 6, 2008. doi:10.4203/ccp.88.6 Keywords: composite materials, adaptive, optimisation, finite element, experiment. Summary Shape-adaptive structures have applications in a number of fields for example the INCOMPRO (Intelligent Composite Products) project [1] designed and produced shape-adaptive structures as diverse as yacht booms, marine propellers, floor panels and pump impellers. The particular field of application of interest to the authors is flexible composite marine propellers. The paper presents a design method for shape-adaptive structures that seeks to determine, by the use of an optimisation technique, the composite lay-up and unloaded structural shape such that a structure will deform into a series of desired shapes at specified loading or operating conditions. Two or more target shapes and their loads are the starting point and the unloaded structure shape and composite material lay-up is the output of the optimisation procedure. The objective of the optimisation is to minimise the distance between the predicted unloaded shapes calculated from the various target shapes by adjusting the composite lay-up. The method is based on the design of deformation method of Kress and Ermanni [2]. Experiments were conducted on composite point-loaded cantilever specimens designed to produce coupled bend-twist behaviour. Loads, deflections and strains were measured during the tests and substantial deformations were observed. Results from these experiments were used to validate some aspects of the shape-adaptive design method. Two of the measured conditions of specimen load and loaded shape were taken as target shapes and used as input to the optimisation and the unloaded shape and composite lay-up were the output. The predicted unloaded shape and lay-up were compared with those of the actual specimen. The results of the validation exercise are disappointing. Relatively small deficiencies in the ability of the finite element model to predict deformations (3 to 4%) resulted in large differences (~30%) in the predicted ply proportions at different angles. That said, differences in stiffness, determined by comparing terms of the bending elastic modulus matrix, were much smaller (~13% maximum). It was concluded that the quality of the predictions from the structural model, for example the finite element model, is critical to the accurate analysis and design of shape-adaptive structures. In particular, the determination of material properties is important with care required to ensure that the make-up of the material test samples, e.g. fibre volume fraction, closely matches that of the plies in the finished structure. References 1 A. Kamoulakos, "INtelligent COMposite PROducts", Final Report submitted to the European Community (Project BE-98-5505, Contract BRPR-CT98-9006), October, 2002. 2 G. Kress, P. Ermanni, "Design of Deformation: Concept, Algorithms, and Sample Calculations", Proc Int. IMS Project Forum, Monte Verità, Ascona, Switzerland, October 6-9, 2001. 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