Aircraft Fuselage Loading

A new passenger plane is being designed with a composite fuselage skin. The fibers will be placed in four different directions; 1) along the length of the fuselage or longitudinal (long) direction, 2) around the circumferential (circ) direction, 3) 30^o from the longitudinal fibers, and 4) -30^o from the longitudinal fibers. The skin is made from multiple layers of graphite reinforced epoxy, but the fibers are only placed in the four directions as described.

What is known:

• The stress in the longitudinal direction, σ_long, is 50 ksi.
• The stress in the circumferential direction, σ_circ, is 25 ksi.
• The twisting of the fuselage causes a shear stress, τ_twist of 25 ksi.

What is the normal and shear stress in the direction of the 30^o and -30^o fibers?

• Using the stress analysis equations, rotate the stress state to plus and minus 30 degrees.