The ever increasing size of wind turbines poses a number of design issues for the industry, like increasing component mass and fatigue loads. An interesting concept for reducing fatigue loads is the implementation of spanwise distributed devices to control the aerodynamic loading along the span of the blade, thus mitigating fl uctuations in loading and adding damping to the blade modes. This is usually referred to as the smart rotor concept. In the design of such a rotor, as compared to a traditional one, the integration of sensors and actuators poses additional design challenges. In the research discussed in this paper, a scaled smart rotor was designed and constructed to study its fatigue load reduction potential. A 1.8 m diameter rotor was manufactured and equipped with trailing-edge fl aps. The fl aps were based on piezo electric Thunder actuators that allow for high-frequent actuation. The dynamic strain behaviour of the blade was analysed for optimal placement of the sensors. Several sensors that record the strains and accelerations at different locations along the blade were implemented, but the controller was based on a piezo electric strain sensor. The rotor blades were mounted on a small turbine in the Delft University's Open Jet Facility wind tunnel and a mathematical state space model was obtained by using dedicated system identifi cation techniques. Single-Input Single-Output, Multi-Input Multi-Output H ∞ feedback and feedforward controllers were designed, each focusing on different parts of the load spectrum. The rotor was tested at 0 and 5° yaw angles, with and without load control. A signifi cant reduction of the dynamic loads was attained.

Access and use of this website and the material on it are subject to the Terms and Conditions set forth at Evaluating the flow stress of aerospace alloys for tube hydroforming process by free expansion testing Saboori, M.; Champliaud, H.; Gholipour, J.; Gakwaya, A.; Savoie, J.; Wanjara, P.http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/jsp/nparc_cp.jsp?lang=fr L'accès à ce site Web et l'utilisation de son contenu sont assujettis aux conditions présentées dans le site LISEZ CES CONDITIONS ATTENTIVEMENT AVANT D'UTILISER CE SITE WEB. NRC Publications Record / Notice d'Archives des publications de CNRC:http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/ctrl?action=rtdoc&an=21272131&lang=en http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/ctrl?action=rtdoc&an=21272131&lang=fr READ THESE TERMS AND CONDITIONS CAREFULLY BEFORE USING THIS WEBSITE.http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/jsp/nparc_cp.jsp?lang=en Vous avez des questions? Nous pouvons vous aider. Pour communiquer directement avec un auteur, consultez la première page de la revue dans laquelle son article a été publié afin de trouver ses coordonnées. Si vous n'arrivez pas à les repérer, communiquez avec nous à PublicationsArchive-ArchivesPublications@nrc-cnrc.gc.ca. Questions? Contact the NRC Publications Archive team atPublicationsArchive-ArchivesPublications@nrc-cnrc.gc.ca. If you wish to email the authors directly, please see the first page of the publication for their contact information. NRC Publications Archive Archives des publications du CNRCThis publication could be one of several versions: author's original, accepted manuscript or the publisher's version. / La version de cette publication peut être l'une des suivantes : la version prépublication de l'auteur, la version acceptée du manuscrit ou la version de l'éditeur. For the publisher's version, please access the DOI link below./ Pour consulter la version de l'éditeur, utilisez le lien DOI ci-dessous.http://doi.org/10.1007/s00170-014-5670-5International Journal of Advanced Manufacturing Technology, 72, 9-12, pp. 1275-1286, 2014 ORIGINAL ARTICLE Evaluating the flow stress of aerospace alloys for tube hydroforming process by free expansion testing Abstract In order to obtain accurate tube hydroforming (THF) simulation results, one of the important inputs in the finite element model (FEM) of the process is the mechanical response of the material during THF. Generally, the mechanical response is defined by the stress-strain behavior that can be determined from tensile testing of the specimens extracted either from the sheet used for roll forming of the tubes or directly from the tubes. More recently, free expansion testing has been used to characterize the mechanical response of the material for hydroforming applications. The free expansion test can emulate process conditions similar to those found during THF, and as such, can be used to obtain reliable and accurate information on the mechanical response/properties of the tubular material. The aim of this research is to present an approach for evaluating the s...

No abstract

No abstract

Torsional stiffness or rigidity is a crucial characteristic in the design of transmission devices, including harmonic drives (HDs). Among the various design aspects constituting a reduction mechanism in robotic systems, torsional stiffness is an important factor for positioning accuracy and control issues. One of the major advantages of HDs is their capacity to present a high reduction ratio while maintaining a small hardware size. However, manufacturing these drives remains a complex and costly process due to the high precision of its machined components; as a result, the use of such drives is still limited only to high-end mechanical products and technologies. Given these costs, numerical analysis becomes an effective alternative for obtaining valuable data through simulations, without the need for prototypes. This article presents a finite-element model to reproduce the behaviour of the torsional stiffness of an HD. The numerical model allows an evaluation of the effects of various geometrical parameters on the torsional stiffness of the HD. The numerical model of the HD can be used for optimization purposes, i.e. to develop an HD with a high torque capacity combined with a high-rated lifespan.

No abstract

No abstract

No abstract