A mathematical model for calculating cross-sectional properties of modern wind turbine composite blades

A wind turbine blade generally has complex structures including several layers of composite materials with shear webs. It is essential but also inherently difficult to accurately and rapidly calculate the cross-sectional properties of a complex composite blade for the structural dynamics and aeroelasticity analysis of the blade. In this paper, a novel mathematical model for calculating the cross-sectional properties of composite blades has been developed by incorporating classical lamination theory (CLT) with extended Bredt-Batho shear flow theory (EBSFT). The mathematical model considers the shear web effects and warping effects of composite blades thus greatly improves the accuracy of torsional stiffness calculation compared with the results from direct use of 3D laminate theories. It also avoids complicated post-processing of force-displacement data from computationally expensive 3D finite-element analysis (FEA) thus considerably improves the computational efficiency. A Matlab program was developed to verify the accuracy and efficiency of the mathematical model and a series of benchmark calculation tests were undertaken. The results show that good agreement is achieved comparing with the data from experiment and FEA, and improved accuracy of torsional stiffness calculation due to consideration of the shear web effects is observed comparing with an existing cross-sectional analysis code PreComp.

[1]  Inderjit Chopra,et al.  Structural behavior of two-cell composite rotor blades with elastic couplings , 1991 .

[2]  Daniel L. Laird,et al.  Identification and Use of Blade Physical Properties , 2005 .

[3]  Carlos E. S. Cesnik,et al.  VABS: A New Concept for Composite Rotor Blade Cross-Sectional Modeling , 1995 .

[4]  S. Timoshenko,et al.  THEORY OF PLATES AND SHELLS , 1959 .

[5]  Mohamed Shama.  Torsion and Shear Stresses in Ships , 2010 .

[6]  L. Librescu,et al.  Thin-Walled Composite Beams: Theory and Application , 2006 .

[7]  Kappyo Hong,et al.  Lateral buckling of I-section composite beams , 2002 .

[8]  Olivier A. Bauchau,et al.  Aerospace structural analysis , 2002 .

[9]  J. Berthelot,et al.  Composite Materials: Mechanical Behavior and Structural Analysis , 1999 .

[10]  G. Bir,et al.  Preliminary Structural Design of Composite Blades for Two- and Three-Blade Rotors , 2004 .

[11]  Daniel L. Laird,et al.  NuMAD User's Manual , 2001 .

[12]  M. Borri,et al.  Anisotropic beam theory and applications , 1983 .

[13]  Walter D. Pilkey.  Analysis and design of elastic beams , 2002 .

[14]  Daniel L. Laird,et al.  Introduction to NuMAD: A numerical manufacturing and design tool , 1998 .

[15]  Daniel L. Laird,et al.  Extraction of equivalent beam properties from blade models , 2007 .

[16]  V. H. Cortínez,et al.  A one dimensional discrete approach for the determination of the cross sectional properties of composite rotor blades , 2015 .

[17]  J. Reddy.  Mechanics of laminated composite plates and shells : theory and analysis , 1996 .

[18]  Daniel L. Laird,et al.  Modeling of Blades as Equivalent Beams for Aeroelastic Analysis , 2003 .

[19]  G. S. Bir,et al.  User's Guide to PreComp (Pre-Processor for Computing Composite Blade Properties) , 2006 .

[20]  Seunghye Lee,et al.  Flexural–torsional behavior of thin-walled composite beams , 2004 .

[21]  Thomas,et al.  [American Institute of Aeronautics and Astronautics 43rd AIAA Aerospace Sciences Meeting and Exhibit - Reno, Nevada ()] 43rd AIAA Aerospace Sciences Meeting and Exhibit - Numerical Simulation of Aerodynamic Plasma Actuator Effects , 2005 .

[22]  Matthew Stables,et al.  Nonlinear aeroelastic modelling for wind turbine blades based on blade element momentum theory and geometrically exact beam theory , 2014 .