Fatigue sensitivity analysis using complex variable methods

A high-fidelity multidisciplinary analysis and gradient-based optimization tool for rotorcraft aero-acoustics is presented. Tightly coupled discipline models include physics-based computational fluid dynamics, rotorcraft comprehensive analysis, and noise prediction and propagation. A discretely consistent adjoint methodology accounts for sensitivities of unsteady flows and unstructured, dynamically deforming, overset grids. The sensitivities of structural responses to blade aerodynamic loads are computed using a complex-variable approach. Sensitivities of acoustic metrics are computed by chain-rule differentiation. Interfaces are developed for interactions between the discipline models for rotorcraft aeroacoustic analysis and the integrated sensitivity analysis. The multidisciplinary sensitivity analysis is verified through a complex-variable approach. To verify functionality of the multidisciplinary analysis and optimization tool, an optimization problem for a 40% Mach-scaled HART-II rotor-and-fuselage configuration is crafted with the objective of reducing thickness noise subject to aerodynamic and geometric constraints. The optimized configuration achieves a noticeable noise reduction, satisfies all required constraints, and produces thinner blades as expected. Computational cost of the optimization cycle is assessed in a high-performance computing environment and found to be acceptable for design of rotorcraft in general level-flight conditions.

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Further applications of complex variable methods to electrochemical machining problems

Journal of Engineering Mathematics ◽

10.1007/bf01535110 ◽

1971 ◽

Vol 5 (3) ◽

pp. 233-240 ◽

Cited By ~ 12

Author(s):

R. C. Hewson-Browne

Keyword(s):

Complex Variable ◽

Electrochemical Machining ◽

Complex Variable Methods

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Fatigue sensitivity analysis of steel catenary riser near touchdown point

Journal of Shanghai Jiaotong University (Science) ◽

10.1007/s12204-017-1876-7 ◽

2017 ◽

Vol 22 (5) ◽

pp. 570-576 ◽

Cited By ~ 1

Author(s):

Kunpeng Wang ◽

Chunyan Ji ◽

Hongxiang Xue ◽

Wenyong Tang

Keyword(s):

Sensitivity Analysis ◽

Steel Catenary Riser ◽

Touchdown Point ◽

Fatigue Sensitivity

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FATIGUE SENSITIVITY ANALYSIS FOR THE CURVED LAYERED COMPOSITE BEAM

Brittle Matrix Composites 7 ◽

10.1533/9780857093103.477 ◽

2003 ◽

pp. 477-484

Author(s):

Ł. FIGIEL ◽

M. KAMIŃSKI

Keyword(s):

Sensitivity Analysis ◽

Composite Beam ◽

Layered Composite ◽

Fatigue Sensitivity

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Potential flow over a submerged rectangular obstacle: Consequences for initiation of boulder motion

European Journal of Applied Mathematics ◽

10.1017/s0956792519000214 ◽

2019 ◽

Vol 31 (4) ◽

pp. 646-681 ◽

Cited By ~ 2

Author(s):

J. G. HERTERICH ◽

F. DIAS

Keyword(s):

Fluid Flow ◽

Complex Variable ◽

Potential Flow ◽

Two Dimensional ◽

Wake Region ◽

Local Flow ◽

Slowing Down ◽

Complex Variable Methods ◽

Drag And Lift ◽

Rectangular Obstacle

AbstractSteady two-dimensional fluid flow over an obstacle is solved using complex variable methods. We consider the cases of rectangular obstacles, such as large boulders, submerged in a potential flow. These may arise in geophysics, marine and civil engineering. Our models are applicable to initiation of motion that may result in subsequent transport. The local flow depends on the obstacle shape, slowing down in confining corners and speeding up in expanding corners. The flow generates hydrodynamic forces, drag and lift, and their associated moments, which differ around each face. Our model replaces the need for ill-defined drag and lift coefficients with geometry-dependent functions. We predict smaller flow velocities to initiate motion. We show how a joint-bound boulder can be transported against gravity, and analyse the influence of a wake region behind an isolated boulder.

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