ESDU A-Z Index: D-DIG

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| D-DIG | dih-dz |

d'Alembert's Principle

Use in Calculation of Forces and Internal Stresses in Accelerated Motion, 94009

Damage

see: Fatigue Under Variable Amplitude Loading

Damage Tolerance

see: Crack Length

Dampers

To Control Duct Noise

see: Noise in Air-Conditioning Duct Systems

Use to Improve Aircraft Lateral Control

see: Lateral Stability and Response

Damping

see also: Damping Ratio

Acoustic Radiation Damping: beams and plates, TM 183
Aircraft: wings, fuselages, TM 183
Buildings and Structures: discussion of sources and effect of amplitude, 83009; methods of measuring, 77032, 83009; methods of supplementing, 77032, 83009; methods of supplementing to reduce response of cylinders, 79025; model tests to determine, 83009; representation in response equations, 77032
Compendium of Vibration Damping Data for Aerospace Structures, TM 183
Discussion of Sources in Structures: acoustic (fluid), 91012; material (hysteretic), 91012; structural, 91012
Effect on Sound Power Radiation: from dynamically excited rectangular plate, 00002
Fibre-Reinforced Laminated Composite Plates: damping of composites, TM 183; program for damping, 85012
Linearised Coefficients for Hydrodynamic Axial Groove Journal Bearings: database, 95023
Materials Used to Increase Structural: effects of frequency and temperature on loss factor and modulus, 91012, 92001; values of specific damping capacity, 85012; variation of loss factor and modulus with frequency and temperature for specific, 92001
Measures for Linear Systems: conversion between, 67038; conversion between for small damping, 73011, 91012; definitions, 22001, 67038, 73011, 77032, 83009, 91012
Methods of Increasing Structural: general discussion, 91012; materials available for treatment, 91012, 92001; use of additional constrained or free layers, 91012; use of tuned dampers, 91012
Prediction of Damping: composite plates and honeycomb panels, TM 183
Relationship of Aerodynamic to Airforce Coefficients (Flutter Derivatives), 82020
Satellites: satellite launch vehicles, spacecraft, TM 183
Tube Bundles in Shell-and-Tube Heat Exchangers: in gas or liquid flows, 87019
Use of Layered Treatments to Increase Structural: damping treatments, TM 183; estimation of increase due to free layers, 91012, 91013; estimation of increase due to multiple constrained layers, 91012, 91013; estimation of increase due to single constrained layer, 91012, 91013; loss factor and modulus of specific layer materials, 92001
Use of Tuned Dampers to Increase Structural, 91012
Values of Acoustic: for suppression of resonance in crossflow through tube banks, 88028

Damping Angle

Definition for Linear System, 67038

Damping Coefficient

Linear System

see also: Critical Damping Coefficient

definition, 22001

Damping Index

Definition for Linear System, 67038

Damping Materials

Use to Provide Additional Structural Damping, 91012: effects of frequency and temperature on loss factor and modulus, 91012
Variation of Loss Factor and Modulus With Frequency and Temperature for Specific, 92001

Damping Ratio

Aerodynamic Contribution: buildings and structures, 83009, 87035, 88019, 89049
Foundation Contribution: brief discussion of soil/structure interaction, 83009
Linear System: definition, 22001, 67038, 73011, 77032, 83009, 91012
Relationship With Loss Factor Used in Statistical Energy Analysis, 99009
Structural Contribution: approximate data, 77032, 87035, 88019, 91001, 96031; estimation for first translational mode of tall buildings, 83009, 91001; estimation for torsional and second-order translational modes of tall buildings, 91001
Typical Values: composite panels, 91012, TM 183; honeycomb sandwich panels, 73011, 91012, TM 183; stiffened panels, 73011, 91012, 99009, TM 183
Use as Parameter Defining Dynamical Similarity, 77032: inclusion in stability parameter, 79025
Variation With Frequency: curved or flat riveted skin-stringer panels, 73011; honeycomb sandwich panels, 73011, TM 183; integrally-machined panels, 73011

Data Analysis

see: Beta Functions; Curve Fitting; Regression; Similarity Laws; Statistics

Deadzone

Representation by Describing Functions in Analysis of Non-Linear System, 84009

Decelerators

see: Parachutes

Decomposition Analysis

Shell-and-Tube Heat Exchanger Network Design Using Process Integration: optimisation of costs and utility consumption, 00043

Degrees of Freedom

Statistics: definition, 91017, 91041, 92040

Delamination

Criterion for Prediction in Composite Plates From Interlaminar Stresses at Free Edges, 95028: comparison with experimental data for specific cases, 95028
Criterion for Prediction Under Through-Thickness Stresses, 94019
Detection by Non-Destructive Examination: selection of method and minimum detectable flaw, 91027
In Laminated Plates Tapered in Thickness by Ply Drop-Off: program to predict uniaxial load for, 91003; use of fracture mechanics to predict, 91003
In Specially-Orthotropic Corner Section: program to predict bending moment, radial shear and tangential direct load for, 94019

Delay Times

see: Abandoned Take-Off; Landing

Delta Wings

see also: Indicial Aerodynamics; Slender Wings; Wing-Body Combination; Wings

Contribution to Airframe Noise, 90023
Rolling Moment Due to Rollingat Supersonic Speeds: effect of interference from cylindrical body, AERO A.S.06.03.02; used in three- or four-wing arrangements, AERO A.S.06.03.01, AERO A.S.06.03.03
Sharp-Edged Cropped or Uncropped of Low Aspect Ratio: centre of pressure in subsonic flow, 95022; normal force and pitching moment in supersonic flow, 90013; normal force in subsonic flow, 93034

Density

see also: Air

Various Ceramic, Metallic and Polymer Materials, 84041
Various Liquids, 83046, 87027
Various Metallic Materials: aluminium, copper, magnesium and titanium alloys, and nickel steels and steels 00932 (MMDH)
Various Synthetic Lubricants, 94020

Depression

Description of Characteristics and Formation in Atmosphere, 87034

Derivatives

see also: Hinge Moment

Axes Transformation, 67004, 86041

Comparison of Alternative Definitions and Notation, 86021

Concept and Definition, 67003, 77032, 86021

Force Variation With Incidence

beam sections, bridge decks and buildings, 93013

Lift-Curve Slope (Z sub w, C sub L alpha or C sub z alpha)

see: Lift-Curve Slope

Longitudinal

calculation from force and moment coefficients, 86021

Notation, 67001, 67002, 67003, 86021

Pitching Moment Due to Acceleration in Heave (M sub w dot or C sub m alpha dot)

forebody-cylinders, low incidence/supersonic speeds, with or without boat-tailing and fins, 91004

Pitching Moment Due to Heave (M sub w or C sub m alpha)

forebody-cylinders with boat-tailing at Mach Numbers up to 5, 87033, 89008

forebody-cylinders without boat-tailing at Mach Numbers up to 5, 89008

Pitching Moment Due to Rate of Pitch (M sub q or C sub mq)

accuracy of prediction for wing/body/tail combination, 90010

contribution due to body at subsonic speeds, 90010

contribution due to tailplane and wing at subsonic speeds, 90010

contribution due to wing at supersonic speeds, AERO W.S.08.03.02

effect of wing/body interference at subsonic speeds, 90010

forebody-cylinders, low incidence/supersonic speeds, with or without boat-tailing and fins, 91004

Rolling Moment Due to Aileron Deflection (L sub xi or C sub l delta a)

estimation at low speeds, 88013, 88040

Rolling Moment Due to Rate of Roll (L sub p or C sub lp), AERO A.06.01.00

contribution due to dihedral, 85006

contribution due to single fin/tailplane combination, 83006

contribution due to wing, AERO A.06.01.01

contribution due to wing at supersonic speeds, AERO A.S.06.03.01

effect of interference on wing from cylindrical body at supersonic speeds, AERO A.S.06.03.02

example of calculation for complete aircraft, 85010

three- or four-wing arrangements on cylindrical body, AERO A.S.06.03.01, AERO A.S.06.03.03

use of component contributions in prediction for complete aircraft, 85010

Rolling Moment Due to Rate of Yaw (L sub r or C sub lr), AERO A.06.01.00

bibliography on contribution due to wing in separated flow, 72021

contribution due to fin, 82017

contribution due to flaps, 72021

contribution due to wing in attached flow, 72021

example of calculation for complete aircraft, 84002

use of component contributions in prediction for complete aircraft, 84002

Rolling Moment Due to Rudder Deflection (L sub zeta or C sub l delta r)

estimation at low speeds, 87008

Rolling Moment Due to Sideslip (L sub v or C sub l beta), AERO A.06.01.00

accuracy of prediction for complete aircraft, 81032

comparison of experimental and predicted variation with incidence, 81032

contribution due to body, 00025, 73006

contribution due to flaps, 00025, 80034

contribution due to full-span dihedral, 00025, AERO A.06.01.03

contribution due to nacelles (on wing for propeller driven aircraft), 00025, TM 178

contribution due to nacelles (turbine engine rear-fuselage mounted), 73006

contribution due to nacelles (turbine engine underwing), 00025, 73006

contribution due to part-span dihedral, 00025, AERO A.06.01.09

contribution due to single fin (fuselage height/width near unity), 00025, 82010

contribution due to single fin merging into fuselage, AERO C.01.01.01

contribution due to single or twin fins (range of fuselage height/width), 93007

contribution due to tailplane-mounted twin fins, 92007

contribution due to wing in attached flow, 00025, 80033

effect of propellers, 06012

effect of wing-body geometry and wing position, 00025, 73006

examples of calculation for complete aircraft, 00025, 81032

program to calculate for complete aircraft, 00025

tailplane effects, 00025, 81032, 82010, 93007

use of component contributions in prediction for complete aircraft, 00025, 81032

Rolling Moment Due to Spoiler Deflection

see: Spoilers

Sideforce Due to Rate of Roll (Y sub p or C sub yp), AERO A.07.01.00

contribution due to dihedral, 85006

contribution due to single fin/tailplane combination, 83006

contribution due to wing (zero camber, dihedral and twist), 81014

example of calculation for complete aircraft, 85010

use of component contributions in prediction for complete aircraft, 85010

Sideforce Due to Rate of Yaw (Y sub r or C sub yr), AERO A.07.01.00

contribution due to body, 83026

contribution due to fin, 82017

example of calculation for complete aircraft, 84002

use of component contributions in prediction for complete aircraft, 84002

Sideforce Due to Rudder Deflection (Y sub zeta or C sub y delta r)

estimation at low speeds, 87008

Sideforce Due to Sideslip (Y sub v or C sub y beta), AERO A.07.01.00

accuracy of prediction for complete aircraft, 82011

contribution due to flaps, 00025, 81013

contribution due to nacelles (on wing for propeller driven aircraft), 00025

contribution due to nacelles (turbine engine rear-fuselage mounted), 79006

contribution due to nacelles (turbine engine underwing), 00025, 79006

contribution due to single fin (fuselage height/width near one), 00025, 82010

contribution due to single fin merging into fuselage, AERO C.01.01.01

contribution due to single or twin fins at supersonic speeds, 91031

contribution due to single or twin fins (range of fuselage height/width), 93007

contribution due to single or twin ventral fins at subsonic or supersonic speeds, 92029

contribution due to tailplane-mounted twin fins, 92007

discussion of contribution due to tailplane, 82011

effect of wing-body-tailplane interference on fin contribution at supersonic speeds, 91031

estimation for wing-body combination, 00025, 79006

examples of calculation for complete aircraft, 00025, 82011

program to calculate for complete aircraft, 00025

tailplane effects, 00025, 81032, 82010, 93007

use of component contributions in prediction for complete aircraft, 00025, 82011

Yawing Moment Due to Aileron Deflection (N sub xi or C sub n delta a)

estimation at low speeds, 88029, 88040

Yawing Moment Due to Rate of Roll (N sub p or C sub np), AERO A.07.01.00

contribution due to dihedral, 85006

contribution due to single fin/tailplane combination, 83006

contribution due to wing (zero camber, dihedral and twist), 81014

example of calculation for complete aircraft, 85010

use of component contributions in prediction for complete aircraft, 85010

Yawing Moment Due to Rate of Yaw (N sub r or C sub nr), AERO A.07.01.00

bibliography on contribution due to wing in separated flow, 71017

contribution due to body, 83026

contribution due to fin, 82017

contribution due to flaps, 71017

contribution due to wing in attached flow, 71017

example of calculation for complete aircraft, 84002

use of component contributions in prediction for complete aircraft, 84002

Yawing Moment Due to Rudder Deflection (N sub zeta or C sub n delta r)

estimation at low speeds, 87008

Yawing Moment Due to Sideslip (N sub v or C sub n beta), AERO A.07.01.00