97 Analysis of combined open and closed sections

In some cases the cross-section of a beam is formed by a combination of open and closed components. For example, a wing section in the region of an undercarriage bay could take the form shown in Fig. 9.41 in which the nose portion is a single cell closed section and the cut-out forms an open channel section. Such composite sections may be analysed using, where appropriate, a combination of the methods

Fig. 9.41 Wing section comprising open and closed components.

Fig. 9.41 Wing section comprising open and closed components.

The centroid of area C lies on the axis of symmetry at some distance y from the upper surface of the beam section. Taking moments of area about this upper surface

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

which gives y — 75 mm. The second moment of area of the section about Cx is given by

2 x 100J 12

0 0

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