Optimization of Airfoil Blend Limits with As-manufactured Geometry Finite Element Models

2021 ◽  
Author(s):  
Jeffrey Brown ◽  
Alex Kaszynski ◽  
Daniel Gillaugh ◽  
Emily Carper ◽  
Joseph Beck
Keyword(s):  
Finite Element ◽  
Structural Integrity ◽  
Structural Response ◽  
Finite Element Models ◽  
Optimization Approach ◽  
Airfoil Surface ◽  
Repair Capacity ◽  
Cloud Data ◽  
Geometry Model ◽  
Geometric Point

Abstract Conventional airfoil blend repair limits are established using nominal, design intent geometry. This convention does not explicitly consider inherent blade-to-blade structural response variations associated with geometric manufacturing deviations. In this work, we explore whether accounting for these variations leads to significant differences in blend depths and develop a novel approach to effectively predict blade-specific blend allowables. These blade-specific values maximize part repairability according to their proximity to defined structural integrity constraints. The methodology is demonstrated on as-manufactured geometry of an compressor rotor. Geometric point cloud data of this rotor is used to construct as-built finite element models of each airfoil. The effect of two large blends on these airfoils demonstrates the opportunity of blade-specific blend limits. A new approach to determine each airfoil's blend repair capacity is developed that uses sequential least squares quadratic programming and a parametric blended blade FEM that accounts for manufacturing geometry variations and variable blend geometry. A mesh morphing algorithm modifies a nominal geometry model to match the as-built airfoil surface and blend geometry. Numerical optimization maximizes blend depth values within frequency, mode shape, and high cycle fatigue (HCF) constraint boundaries. Large variations in blend depth allowables between blades are found and competing structural integrity criteria are responsible for their limits. It is also shown that, despite complex modal behavior caused by eigenvalue veering, the proposed optimization approach converges. The developed methodologies may be used to extend blend limits, enable continued operations, and reduce sustainment costs.

Optimization of Airfoil Blend Limits With As-Manufactured Geometry Finite Element Models

2020 ◽  
Author(s):  
Jeffrey M. Brown ◽  
Alex A. Kaszynski ◽  
Daniel L. Gillaugh ◽  
Emily B. Carper ◽  
Joeseph A. Beck
Keyword(s):  
Finite Element ◽  
Structural Integrity ◽  
Structural Response ◽  
Finite Element Models ◽  
Optimization Approach ◽  
Airfoil Surface ◽  
Repair Capacity ◽  
Cloud Data ◽  
Geometry Model ◽  
Geometric Point

Abstract Conventional airfoil blend repair limits are established using nominal, design intent geometry. This convention does not explicitly consider the inherent blade-to-blade structural response variation associated with geometric manufacturing deviations. In this work, we explore whether accounting for these variations leads to significant differences in blend depths and develop a novel approach to effectively predict blade-specific blend allowables. These blade-specific values maximize the part repairability according to their proximity to defined structural integrity constraints. The methodology is demonstrated on the as-manufactured geometry of an aerodynamic research rig compressor rotor. Geometric point cloud data of this rotor is used to construct as-built finite element models (FEMs) of each airfoil. The effect of two large blends on these airfoils demonstrates the opportunity of blade-specific blend limits. A new approach to determine each airfoil’s blend repair capacity is developed that uses sequential least squares quadratic programming and a parametric blended blade FEM that accounts for manufacturing geometry variations and variable blend geometry. A mesh morphing algorithm modifies a nominal geometry model to match the as-built airfoil surface and blend geometry. The numerical optimization maximizes blend depth values within frequency, mode shape, and high cycle fatigue (HCF) constraint boundaries. It is found that there are large variations in blend depth allowables between blades and competing structural integrity criteria are responsible for their limits. It is also found that, despite complex modal behavior caused by eigenvalue veering, the proposed optimization approach converges. The developed methodologies may be used in the future to extend blend limits, enable continued operations, and reduce sustainment costs.

Finite Element Analysis for Nozzle With External Loads

2011 ◽  
Author(s):  
Hak-Sung Lee ◽  
Chang-Hoon Ha ◽  
Tae-Jung Park
Keyword(s):  
Finite Element ◽  
Stress Intensity ◽  
Pressure Vessel ◽  
Maximum Stress ◽  
Structural Integrity ◽  
Finite Element Models ◽  
Pressurized Water ◽  
Dimensional Finite Element ◽  
Maximum Stress Intensity ◽  
External Loads

Various kinds of nozzles are attached to a pressure vessel including Steam Generator (SG) in a pressurized water reactor plant. The downcomer feedwater nozzle on the upper vessel shell and the economizer feedwater nozzle in the lower vessel shell of the SG are representative nozzles which have a non axi-symmetric shape. In most cases, external loads composed with forces and moments are imposed on those nozzles during the plant operation. In order to evaluate structural integrity of junctures between the nozzles and vessels in compliance with the ASME Boiler and Pressure Vessel Code, Section III, it is essential to find the maximum stress intensity resulting from those loads. Welding Research Council (WRC) Bulletin 297 has been used to find the maximum stress intensity since it is not straightforward to calculate the stress intensity with a non axi-symmetric two dimensional finite element model. However, the compatibility of adopting WRC Bulletin 297 to nozzles which have a variety of geometries shall be considered. Moreover, the applicability of the stress intensity resulting from the bulletin should be into consideration when interested lines where stress intensity linearization is to be performed are not exactly consistent with the line defined in the Bulletin. In this study, the nozzles in cylindrical vessel shells are developed as three dimensional finite element models, which are loaded with unit forces and moments. The stress intensities from finite element models are investigated through a comparison of WRC Bulletin 297. In addition, a methodology to apply the stress intensity results from WRC 297 to different lines is proposed.

Structural Response of Timber-Concrete Composite Beams Predicted by Finite Element Models and Manual Calculations

2014 ◽  
Vol 17 (11) ◽  
pp. 1601-1621 ◽  
Author(s):  
Nima Khorsandnia ◽  
Hamid Valipour ◽  
Keith Crews
Keyword(s):  
Finite Element ◽  
Axial Stress ◽  
Damage Model ◽  
Structural Response ◽  
General Purpose ◽  
Finite Element Models ◽  
Fe Model ◽  
Loading Capacity ◽  
Model Predictions ◽  
Ultimate Loading Capacity

This paper presents the structural response of timber-concrete composite (TCC) beams predicted by finite element models (i.e. continuum-based and 1D frame) and manual calculations. Details of constitutive laws adopted for modelling timber and concrete are provided and application of the Hashin damage model in conjunction with continuum-based FE for capturing failure of timber under bi-axial stress state is discussed. A simplified strategy for modelling the TCC connection is proposed in which the connection is modelled by a nonlinear spring and the full load-slip behaviour of each TCC connection is expressed with a formula that can be directly implemented in the general purpose FE codes and used for nonlinear analysis of TCC beams. The developed FE models are verified by examples taken from the literature. Furthermore, the load-displacement response and ultimate loading capacity of the TCC beams are determined according to Eurocode 5 method and compared with FE model predictions.

Influence of Angle Thickness towards Stiffness and Strength Prediction for Cold-Formed Steel Top-Seat Flange Cleat Connection

2013 ◽  
Vol 479-480 ◽  
pp. 1144-1148 ◽  
Author(s):  
Yeong Huei Lee ◽  
Cher Siang Tan ◽  
M.Md. Tahir ◽  
Shahrin Mohammad ◽  
Poi Ngian Shek ◽  
...  
Keyword(s):  
Finite Element ◽  
Finite Element Modelling ◽  
Structural Integrity ◽  
Structural Performance ◽  
Design Stage ◽  
Strength Prediction ◽  
Finite Element Models ◽  
Steel Framing ◽  
Cold Formed Steel ◽  
Thin Walled

For the connection stiffness and strength prediction, Eurocode has showed an inadequacy as it will be affected by the thin-walled behaviour of cold-formed steel in actual structural performance. This paper performs a study on the connection stiffness prediction for cold-formed steel top-seat flange cleat connection with various angle thickness. Validated finite element modelling technique is applied for further advanced investigation. From the developed finite element models, it was realized that Eurocode has overestimated by the analytical stiffness prediction using component method for the studied connection which reduces the structural integrity in the design stage. A new proposal on connection stiffness prediction with influence of angle thickness for cold-formed steel top-seat flange cleat connection is presented to assist practicing engineers to design the cold-formed connection in light steel framing.

Engineering Studies on Joint Bar Integrity: Part II — Finite Element Analyses

2014 ◽  
Author(s):  
Michael E. Carolan ◽  
David Y. Jeong ◽  
A. Benjamin Perlman
Keyword(s):  
Finite Element ◽  
Structural Integrity ◽  
Structural Response ◽  
Relative Effect ◽  
Structural Performance ◽  
Finite Element Analyses ◽  
Field Surveys ◽  
Engineering Studies ◽  
Toe Angle ◽  
Support Conditions

This paper is the second in a two-part series describing research sponsored by the Federal Railroad Administration (FRA) to study the structural integrity of joint bars. In Part I, observations from field surveys of joint bar inspections conducted on revenue service track were presented [1]. In this paper, finite element analyses are described to examine the structural performance of rail joints under various loading and tie-ballast support conditions. The primary purpose of these analyses is to help interpret and understand the observations from the field surveys. Moreover, the finite element analyses described in this paper are applied to conduct comparative studies and to assess the relative effect of various factors on the structural response of jointed rail to applied loads. Such factors include: discrete tie support (i.e. supported joint versus suspended joint with varying spans between effective ties), bolt pattern (four versus six bolts), initial bolt tension, and easement. In addition, results are shown for 90 lb rail joined with long-toe angle bars compared to 136 lb rail joined with standard short-toe joint bars.

scholarly journals DEVELOPMENT OF FINITE ELEMENT MODELS FOR THE STUDY OF AGEING EFFECTS IN CANDU 6 CONCRETE CONTAINMENT BUILDINGS

2016 ◽  
Vol 5 (1) ◽  
pp. 37-48 ◽  
Author(s):  
Yuqing Ding ◽  
Shahzma Jaffer
Keyword(s):  
Finite Element ◽  
Nuclear Power ◽  
Power Plants ◽  
Structural Integrity ◽  
Finite Element Models ◽  
Reinforcing Bars ◽  
Potential Applications ◽  
Leak Tightness ◽  
Nuclear Structures ◽  
Modelling Assumptions

In nuclear power plants (NPPs), concrete containment buildings (CCBs) provide the final physical barrier against the release of radioactive materials into the environment and protect the nuclear structures housed within the containment building. CCBs have to be maintained to ensure leak tightness and sound structural integrity for the safe operation throughout the life of NPPs. However, the integrity of CCBs may be affected by the ageing of its concrete, post-tensioning cables and reinforcing bars (rebars). Finite element models (FEMs) of CANDU 6 CCBs have been developed using 2 independent finite element programs for the study of the effect of ageing of CCBs. These FEMs have been validated using multiple-source data and have been used for preliminary analyses of the effect of thermal load and ageing degradation on the concrete structure. The modelling assumptions and simplifications, approach, and validation are discussed in this paper. The preliminary analyses for temperature effects and potential applications to the study of ageing degradation in CCBs using the FEMs are briefly introduced.

Finite Element Residual Stress Analysis Applied to Offshore Studless Chain Links

2004 ◽  
Author(s):  
Pedro M. Calas Lopes Pacheco ◽  
Paulo Pedro Kenedi ◽  
Jorge Carlos Ferreira Jorge ◽  
Marcelo Amorim Savi ◽  
Hugo Gama dos Santos
Keyword(s):  
Finite Element ◽  
Residual Stresses ◽  
Structural Integrity ◽  
Wind Waves ◽  
Mooring Line ◽  
Single Element ◽  
Finite Element Models ◽  
Waves And Currents ◽  
Fatigue Life Analysis ◽  
Chain Links

The increasing expansion of deepwater petroleum activities has resulted in new challenges to the design of mooring systems. The complex mooring systems load history, which consists in a combination of wind, waves and currents, could induce nucleation and propagation of cracks in mooring line components. The failure of a single element in a mooring line of an offshore oil exploitation platform can produce incalculable environment damage as well as human and material losses. Offshore mooring line components like chain links must be submitted to a mandatory proof test, dictated by offshore standards, where loads higher than operational loads are applied to the mechanical component, resulting in high levels of residual stresses. Nevertheless, its presence is not considered in traditional design methodologies. Therefore, it is fundamental to develop new and more precise methodologies for assessing the structural integrity of mooring components. In this article, a comparative study is developed considering different approaches: two bidimensional finite element models, two tridimensional finite element models and an analytic model. These analyses establish the drawbacks and goals of using simpler models in the prediction of studless chain links stress distributions and in their fatigue lives. The four finite element models consider large displacements, plasticity and contact phenomena. Moreover, a simple fatigue life analysis is presented, based on SN curve, considering the effect of residual stresses in studless chain links before operation, that is, with loads caused by the proof test.

An Assessment of the Mechanisms of Transformation Plasticity in SA508 Grade 3 Steel during Simulated Welding Thermal Cycles

2014 ◽  
Vol 777 ◽  
pp. 188-193
Author(s):  
John A. Francis ◽  
Richard J. Moat ◽  
Hamidreza Abdolvand ◽  
Alexander Forsey
Keyword(s):  
Finite Element ◽  
Residual Stresses ◽  
Structural Integrity ◽  
External Loading ◽  
Finite Element Models ◽  
Variant Selection ◽  
X Ray Diffraction ◽  
Thermal Cycles ◽  
Heating And Cooling ◽  
Grade 3

Residual stresses in welded joints must be quantified in order to carry out structural integrity assessments on critical nuclear components. This usually requires the application of finite element models for components with wall thicknesses exceeding 50 mm. In ferritic steels, the development of residual stresses is made more complex by the strains associated with the solid-state phase transformations that occur during heating and cooling. Finite element models often do not account for factors that contribute to anisotropy in the transformation strains, such as Greenwood-Johnson plasticity and variant selection. In this work, we search for evidence that might reveal which mechanism (s) contributes to this anisotropy. Coupons of SA508 steel were subjected to simulated welding thermal cycles, with and without external loading, and in-situ X-ray diffraction was used to track changes in crystal structure. The results were checked for evidence of plastic deformation in austenite and variant selection in its daughter phases.

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