Introduction to Aircraft Structural Analysis (Elsevier Aerospace Engineering)

530 CHAPTER 18 Combined Open and Closed Section Beams

Example 18.1
Determine the shear flow distribution in the beam section shown in Fig. 18.2, when it is subjected
to a shear load in its vertical plane of symmetry. The thickness of the walls of the section is 2mm
throughout.

ThecentroidofareaCliesontheaxisofsymmetryatsomedistance ̄yfromtheuppersurfaceofthe
beamsection.Takingmomentsofareaaboutthisuppersurface

( 4 × 100 × 2 + 4 × 200 × 2 )y ̄= 2 × 100 × 2 × 50 + 2 × 200 × 2 × 100 + 200 × 2 × 200

whichgivesy ̄=75mm.
ThesecondmomentofareaofthesectionaboutCxisgivenby

Ixx= 2

(

2 × 1003

12

+ 2 × 100 × 252

)

+ 400 × 2 × 752 + 200 × 2 × 1252

+ 2

(

2 × 2003

12

+ 2 × 200 × 252

)

thatis,

Ixx=14.5× 106 mm^4

Fig.18.2

Beam section of Example 18.1.