Introduction to Aircraft Structural Analysis (Elsevier Aerospace Engineering)

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620 CHAPTER 23 Fuselage Frames and Wing Ribs


Fig.23.1


Cantilever beam of Example 23.1.


Fig.23.2


Free body diagrams of stiffeners JK and HKD in the beam of Example 23.1.


thehorizontalcomponentoftheloadatKisequilibratedlocallybytheaxialloadinthestiffenerJK
andnotbythebendingofstiffenerHKD.Bythesameargument,theverticalcomponentoftheloadat
KisresistedbytheaxialloadinthestiffenerHKD.Theseaxialstiffenerloadsareequilibratedinturn
bytheresultantsoftheshearflowsq 1 andq 2 inthewebpanelsCDKJandJKHG.Thus,weseethat
thewebpanelsresisttheshearcomponentoftheexternallyappliedloadandatthesametimetransmit
thebendingandaxialloadoftheexternallyappliedloadtothebeamflanges;subsequently,theflange
loadsarereactedatthesupportpointsAandE.
ConsiderthefreebodydiagramsofthestiffenersJKandHKDshowninFig.23.2(a)and(b).

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