Page 447 - Aircraft Stuctures for Engineering Student

428 Stress analysis of aircraft components

Fig. 10.68 Determination of Glt.

Finally, the shear modulus qt(= Gd) is determined by assuming that the constituent
materials are subjected to the same shear stress qt as shown in Fig. 10.68. The
displacement A, produced by shear is

in which G, and Gf are the shear moduli of the matrix and filament respectively. Thus

whence

(10.53)

Example IO. 17
A laminated bar whose cross-section is shown in Fig. 10.69 is 500mm long and com-
prises an epoxy resin matrix reinforced by a carbon filament having moduli equal to
5000 N/mm2 and 200 000 N/mm2 respectively; the corresponding values of Poisson’s
ratio are 0.2 and 0.3. If the bar is subjected to an axial tensile load of 100 kN, deter-
mine the lengthening of the bar and the reduction in its thickness. Calculate also the
stresses in the epoxy resin and the carbon filament.

80mm
f *
Fig. 10.69 Cross-section of the bar of Example 10.1 7.