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Book NASA Technical Paper

Download or read book NASA Technical Paper written by and published by . This book was released on 1985 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Nonlinear Finite Element Analysis of the Coupled Thermomechanical Behaviour of Turbine Disc Assemblies

Download or read book Nonlinear Finite Element Analysis of the Coupled Thermomechanical Behaviour of Turbine Disc Assemblies written by Davinder Singh Delhelay and published by . This book was released on 1999 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Comprehensive two and three-dimensional finite element studies are made of the effect of the critical geometric features and interface conditions in the fir-tree region of a gas turbine disc upon the resulting thermomechanical contact stress distribution at the blade-disc interface. In addition to the rotational body forces, the thermal state of a turbine disc made from nickel based super alloy, was determined using realistic boundary temperatures and the assembly was treated as a coupled boundary value problem. Three aspects of the work were accordingly examined. The first was devoted to the validation of the basic finite element model using convergence tests and photoelastic stress analysis. The second was concerned with examining the effect of the flank length and flank angle, inner radius of disc and interfacial friction upon the thermomechanical stress-state of an insulated disc. The third was concerned with the determination of the influence of the skew angle upon the triaxial state of stress and load sharing between the teeth in the turbine disc assembly. Contact between the disc and the blades was modelled using contact elements and the analysis pertain to an insulated disc, with heat conduction being the main form of heat flow. The outcome of the study reveals: (i) the important role played by the temperature and rotation upon the induced thermomechanical contact stresses at the blade-disc interface, and (ii) the effect of the skew angle upon the resulting three dimensional thermomechanical stress state, and the inability of the two-dimensional finite element model to accurately capture the stress gradients at the fir-tree interface and through the thickness.

Book NASA Technical Memorandum

Download or read book NASA Technical Memorandum written by and published by . This book was released on 1994 with total page 492 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Structural Analysis of Composite Wind Turbine Blades

Download or read book Structural Analysis of Composite Wind Turbine Blades written by Dimitris I Chortis and published by Springer Science & Business Media. This book was released on 2013-06-29 with total page 240 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book concerns the development of novel finite elements for the structural analysis of composite beams and blades. The introduction of material damping is also an important aspect of composite structures and it is presented here in terms of their static and dynamic behavior. The book thoroughly presents a new shear beam finite element, which entails new blade section mechanics, capable of predicting structural blade coupling due to composite coupling and/or internal section geometry. Theoretical background is further expanded towards the inclusion of nonlinear structural blade models and damping mechanics for composite structures. The models effectively include geometrically nonlinear terms due to large displacements and rotations, improve the modeling accuracy of very large flexible blades, and enable the modeling of rotational stiffening and buckling, as well as, nonlinear structural coupling. Validation simulations on specimen level study the geometric nonlinearities effect on the modal frequencies and damping values of composite strips of various angle-ply laminations under either tensile or buckling loading. A series of correlation cases between numerical predictions and experimental measurements give credence to the developed nonlinear beam finite element models and underline the essential role of new nonlinear damping and stiffness terms.

Book Nonlinear Legendre Spectral Finite Elements for Wind Turbine Blade Dynamics

Download or read book Nonlinear Legendre Spectral Finite Elements for Wind Turbine Blade Dynamics written by and published by . This book was released on 2014 with total page 15 pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper presents a numerical implementation and examination of new wind turbine blade finite element model based on Geometrically Exact Beam Theory (GEBT) and a high-order spectral finite element method. The displacement-based GEBT is presented, which includes the coupling effects that exist in composite structures and geometric nonlinearity. Legendre spectral finite elements (LSFEs) are high-order finite elements with nodes located at the Gauss-Legendre-Lobatto points. LSFEs can be an order of magnitude more efficient that low-order finite elements for a given accuracy level. Interpolation of the three-dimensional rotation, a major technical barrier in large-deformation simulation, is discussed in the context of LSFEs. It is shown, by numerical example, that the high-order LSFEs, where weak forms are evaluated with nodal quadrature, do not suffer from a drawback that exists in low-order finite elements where the tangent-stiffness matrix is calculated at the Gauss points. Finally, the new LSFE code is implemented in the new FAST Modularization Framework for dynamic simulation of highly flexible composite-material wind turbine blades. The framework allows for fully interactive simulations of turbine blades in operating conditions. Numerical examples showing validation and LSFE performance will be provided in the final paper.

Book NASA Scientific and Technical Publications

Download or read book NASA Scientific and Technical Publications written by and published by . This book was released on 1987 with total page 410 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Engine Structures

Download or read book Engine Structures written by and published by . This book was released on 1988 with total page 232 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Scientific and Technical Aerospace Reports

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 500 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Nonlinear Constitutive Relations for High Temperature Applications

Download or read book Nonlinear Constitutive Relations for High Temperature Applications written by and published by . This book was released on 1983 with total page 380 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Local Strain Redistribution Corrections for a Simplified Inelastic Analysis Procedure Based on an Elastic Finite element Analysis

Download or read book Local Strain Redistribution Corrections for a Simplified Inelastic Analysis Procedure Based on an Elastic Finite element Analysis written by Albert Kaufman and published by . This book was released on 1985 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Monthly Catalogue United States Public Documents

Download or read book Monthly Catalogue United States Public Documents written by and published by . This book was released on 1982-10 with total page 1044 pages. Available in PDF, EPUB and Kindle. Book excerpt: