Introduction to Aircraft Structural Analysis (Elsevier Aerospace Engineering)

392 CHAPTER 13 Airframe Loads or,sinceL=nW(seeSection13.2) n= V^2 gR +cosθ (13.15) Atthelowestpointofthepull-out,θ=0,and n= V^2 ...

13.4 Gust Loads 393 andforverticalequilibrium Lcosφ=W (13.18) or L=Wsecφ (13.19) FromEq.(13.19),weseethattheloadfactornintheturn ...

394 CHAPTER 13 Airframe Loads Fig.13.11 (a) Sharp-edged gust; (b) graded gust; (c) 1−cosine gust. The “sharp-edged” gust was rep ...

13.4 Gust Loads 395 Although the “graded” or “ramp” gust is used as a basis for gust load calculations, other shapes ofgustprofi ...

396 CHAPTER 13 Airframe Loads small.Theincreaseinwinglift Listhengivenby L= 1 2 ρV^2 S ∂CL ∂α u V = 1 2 ρVS ∂CL ∂α u (13.22) whe ...

13.4 Gust Loads 397 whereSTisthetailplaneareaand CL,Ttheincrementoftailplaneliftcoefficientgivenby CL,T= ∂CL,T ∂α uE VE (13.30) ...

398 CHAPTER 13 Airframe Loads 13.4.3 Gust Envelope Airworthinessrequirementsusuallyspecifythatgustloadsshallbecalculatedatcertai ...

Problems 399 or VC>108m/s Thus,forcivilaircraftofthistypehavingcruisingspeedsinexcessof108m/s,thegustcaseisthemost critical.T ...

400 CHAPTER 13 Airframe Loads Ifeachundercarriagewheelweighs2.25kNandisattachedtoanoleostrut,asshowninFig.P.13.1(b),calculate th ...

Problems 401 CalculatethemaneuverloadfactorbothattheCGandatthetailplaneCP,theforwardinertiacoefficient,andthe taillift. Ans. n=3 ...

402 CHAPTER 13 Airframe Loads Fig. P.13.7 At18300m ρ=0.116kg/m^3 Ans. P=267852N, P=36257N, L=271931N,n=1.19. P.13.8 Anaircraftof ...

CHAPTER 14 Fatigue.................................................................................... Fatiguehasbeendiscussedbr ...

404 CHAPTER 14 Fatigue catastrophicdamageoccurs.Attheendofthislife,thestructuremustbereplacedeventhoughthere maybenodetectablesi ...

14.3 Fatigue Strength of Components 405 fluctuations.Theundercarriageisretractedandlowered;flapsareraisedandlowered;thereisanimp ...

406 CHAPTER 14 Fatigue resulting in a fatigue endurance curve (theS–Ncurve) of the type shown in Fig. 12.2. Such a curve corresp ...

14.3 Fatigue Strength of Components 407 extremevaluedistributions,aremorerealisticandallowtheexistenceofminimumfatigueendurances ...

408 CHAPTER 14 Fatigue Therefore,ifrdifferentcyclesareappliedinwhichastressamplitudeSj(j=1,2,...,r)wouldcause failureinNjcycles, ...

14.4 Prediction of Aircraft Fatigue Life 409 Thecorrespondingfatiguelimitstresswouldthenhavebeen,fromacomparisonwithEq.(14.10), ...

410 CHAPTER 14 Fatigue thedamagecausedbyonecycleisthen1/N(Su).Therefore,fromthePalmgren–Minerhypothesis,when sufficientgustsofth ...

14.4 Prediction of Aircraft Fatigue Life 411 Fig.14.3 Gust exceedance curve. Integrating Eq. (14.19) over the whole range of gus ...