Engineering Optimization: Theory and Practice, Fourth Edition

692 Optimal Control and Optimality Criteria Methods

Figure 12.8 Two-bar truss subjected to horizontal load.

12.8 The problem of the minimum-weight design of the four-bar truss shown in Fig. 1.32

(Problem 1.31) subject to a constraint on the vertical displacement of jointAand limi-

tations on design variables can be stated as follows:

FindX= {x 1 x 2 }Twhich minimizes

f (X)= 0. 1 x 1 + 0. 05773 x 2

subject to

g(X)=

0. 6

x 1

+

0. 3464

x 2

− 0. 1 ≤ 0

xi≥ 4 , i= 1 , 2

where the maximum permissible vertical displacement of jointAis assumed to be 0.01 in.

Solve the problem using the optimality criteria method.