Introduction to Aircraft Structural Analysis (Elsevier Aerospace Engineering)

Problems 161

Fig. P.5.8
Under some system of loading, member 14 carries a tensile stress of 0.7N/mm^2. Calculate the change in
temperature which, if applied to member 14 only, would reduce the stress in that member to zero. Take the
coefficientoflinearexpansionasα= 24 × 10 −^6 /◦CandYoung’smodulusE=70000N/mm^2.

Ans. 5.6◦C.

P.5.9 The plane, pin-jointed rectangular framework shown in Fig. P.5.9(a) has one member (24) which is
loosely attached at joint 2 so that relative movement between the end of the member and the joint may occur
when the framework is loaded. This movement is a maximum of 0.25mm and takes place only in the direc-
tion 24. Figure P.5.9(b) shows joint 2 in detail when the framework is unloaded. Find the value of the load
Pat which member 24 just becomes an effective part of the structure and also the loads in all the members
whenPis 10000N. All bars are of the same material(E=70000N/mm^2 )and have a cross-sectional area
of300mm^2.

Ans. P=294N, F 12 =2481.6N(T), F 23 =1861.2N(T), F 34 =2481.6N(T),F 41 =5638.9N(C),

F 13 =9398.1N(T), F 24 =3102.0N(C).

Fig. P.5.9