Session: 06-04-01: Beam, Plate, and Shell Structures

Paper Number: 167634

Timoshenko Beam Modeling of Realistic Wind Turbine Blades Using Mechanics of Structure Genome 

The increasing wind turbine blade size has challenged predictive capabilities to compute high fidelity and accurate three dimensional FEA results through high computation and time expense. The accepted alternative by industry researchers is to use VABS, a highly renewed cross-sectional analysis tool, which combines the two-dimensional cross-sectional analysis with one-dimensional beam model for accurate and high-fidelity results. However, intrinsic features like curvatures, ply-drop and local buckling estimation are not captured using cross-sections. On the other hand, we cannot surpass the beam model role for complex aeroelastic calculations. Therefore, the existing work demonstrates a solution to use three-dimensional tapered blade segment in place of the cross-section for estimating beam properties.

The paper discusses the unique approach of Mechanics of Structure Genome to extract Timoshenko beam properties of realistic tapered segments containing extra coupling terms for transverse shear stiffness using boundary solution constraints. Secondly, the paper discusses the extraction of VABS like cross-section stiffness at wind blade stations using all three Euler angles to define the rotation about beam, circumferential and transverse direction. This gives more flexibility to user to go either one among entire tapered wind blade segment with solid elements and cross-sectional stiffness. Lastly, the paper discusses about extracting the inertial properties of wind blade segment in form of VABS like mass matrix of wind blade segment both for cross-section and three-dimensional wind blade segments. The additive advantage of mass matrix with three dimensional segments is having inertial mass properties with beam axis contribution which is missing from the cross-sectional mass properties.  

The numerical implementation of Timoshenko beam model is implemented in an open-source platform, OpenSG based on FEniCSx backend. The unique form compilation and automated partial differential equations solver allow user to provide general realistic models with mesh elements like hexahedron, tetrahedron. It allows the research community to add their own models in existing weak form for specific applications. The paper discusses the theoretical formulations using Mechanics of Structure Genome theory and present benchmark cases of realistic wind blade with VABS solid cross-sections for Timoshenko beam properties. The input mesh can directly be taken from pyNuMAD, a versatile tool for wind blade mesh generator, and OpenSG serves in pipeline to provide the beam stiffness properties for homogenization and later for dehomogenization for extracting the three-dimensional displacement and stress fields using input beam loads. The OpenSG repository is publicly available on GitHub page and the existing work to form API generation is under process to make OpenSG library for general usage.

Presenting Author: Akshat Bagla Purdue University

Presenting Author Biography: Akshat is a PhD student in the Multiscale Structural Mechanics laboratory at School of Aeronautics and Astronautics, Purdue University. His research focuses on solving buckling of shell structures problem using Mechanics of Structure Genome (MSG) theory. He is developing an MSG based open-source tool, OpenSG in FEniCSx backend for performing the constitutive modeling of shell and solid elements based composite structures like beam, plate or Cauchy continuum model. His buckling of shell structures problem would predict the three-dimensional local buckling of realistic wind blade composite structures. His research interests are composite structures, solid mechanics and multiscale modeling.

Authors:

Akshat Bagla Purdue University
Ernesto Camarena Sandia National Laboratories
Wenbin Yu Purdue University