The present paper proposes a set of blending constraints expressed in lamination parameter space, applicable during the continuous optimisation of composite structures. Thicknesses and ply orientations of large composite structures are often locally optimised in response to unequal spatial load distribution. During this process, ensuring structural continuity is essential in order to achieve designs ready to be manufactured. Single step stacking sequence optimisations relying on evolutionary algorithms to enforce continuity, through the application of blending rules, are prone to the curse of dimensionality. By contrast, multi-step optimisation strategies including a continuous sub-step can optimise composite structures with reasonable computational effort. However, the discrepancies between continuous and discrete optimisation step result in performance loss during stacking sequence retrieval. By deriving and applying blending constraints during the continuous optimisation, this paper aim is to reduce the performance loss observed between optimisation levels. The first part of this paper is dedicated to the derivation of blending constraints. The proposed constraints are then successfully applied to a benchmark blending problem in the second part of this paper. Numerical results demonstrate the achievement of near-optimal easy-to-blend continuous designs in a matter of seconds.
A dynamic model characterising the effect of microtab deployment on the aerodynamics of its base aerofoil is presented. The developed model predicts the transient aerodynamic coefficients consistent with the experimental and computational data reported in the literature. The proposed model is then used to carry out investigation on the effectiveness of microtabs in load alleviation and lifespan increase of wind turbine blades. Simulating a bang-bang controller, different load rejection scenarios are examined and their effect on blade lifespan is investigated. Results indicate that the range of frequencies targeted for rejection can significantly impact the blade fatigue life. Case studies are carried out to compare the predicted load alleviation amount and the blade lifespan using the developed model with those obtained by other researchers using the steady state model. It is shown that the assumption of an instantaneous aerodynamic response as used in the steady state model can lead to inaccurate results.
Northumbria University has developed Northumbria Research Link (NRL) to enable users to access the University's research output. Copyright © and moral rights for items on NRL are retained by the individual author(s) and/or other copyright owners. Single copies of full items can be reproduced, displayed or performed, and given to third parties in any format or medium for personal research or study, educational, or not-for-profit purposes without prior permission or charge, provided the authors, title and full bibliographic details are given, as well as a hyperlink and/or URL to the original metadata page. The content must not be changed in any way. Full items must not be sold commercially in any format or medium without formal permission of the copyright holder. The full policy is available online: http://nrl.northumbria.ac.uk/policies.html This document may differ from the final, published version of the research and has been made available online in accordance with publisher policies. To read and/or cite from the published version of the research, please visit the publisher's website (a subscription may be required.)Published in Renewable Energy 75 (2015) 102-114 Terence Macquart & Alireza Maheri 1 Integrated Aeroelastic and Control Analysis of Wind Turbine Blades Equipped with MicrotabsTerence Macquart and Alireza Maheri Faculty of Engineering and Environment, Northumbria University, UK AbstractThis paper presents the results of an investigation into the performance of different controllers in active load control of wind turbine blades equipped with microtabs. A bang-bang (BB) controller, a linear quadratic regulator (LQR) a proportional integral derivative (PID) and a sliding mode controller (SMC) are synthesised for load alleviation. The performance of the synthesised controllers in load alleviation is evaluated by employing WTAC (Wind Turbine Aeroelastic and Control), a wind turbine simulator incorporating an unsteady aerodynamic module, a structural analysis module and a control module. The variable-speed pitch-controlled NREL-5MW is adopted as the case study. Using frequency domain analysis it is shown that for the studied case all controllers have more or less the same performance at rejecting the first rotational frequency loads. It is also shown that all controllers are more effective at rejecting loads with lower frequencies. BB and PID controllers, although capable of rejecting low frequency loads, may cause amplification of loads with higher frequencies. Investigating the performance of four controllers at different wind speeds for the studied wind turbine, it is observed that the effectiveness of BB and PID controllers reduces with wind speed but on the other hand SMC and LQR perform better at higher wind speeds. Introducing a new parameter, life index, the performance of different controllers in terms of the actuation wear is investigated. It is shown that LQR cause less actuation wear compared to SMC, while having comparable performance in load alleviation.
The design of composite structures based on fibre angle optimisation rapidly becomes intractable as the number of design variables increases. Lamination parameters can be used instead as intermediate design variables in order to overcome this issue. An extra step is then required in order to convert the optimal design expressed in lamination parameter into feasible blended stacking sequences. However, disparities between the lamination parameter and stacking sequence designs performance are generally observed due to discrepancies between both design spaces. In this paper, the lamination parameter blending constraints recently proposed by the authors are applied to the aeroelastic optimisation of the common research wing model in order to diminish these discrepancies and achieve more realistic lamination parameter designs. A comparison between the optimised designs achieved with and without the proposed blending constraints is carried out to evaluate our approach. Results demonstrate that the application of blending constraints greatly increases the matching quality between lamination parameter and stacking sequence designs, consequently facilitating the retrieval of equivalent blended stacking sequences.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.