ABSTRACT
The objective of this paper is to obtain an optimal weight of wing spar by obtaining
the optimal cross-section parameters of I-section wing spars, subjected to
aerodynamic and mass loads.
Using Matlab codes to apply several methods of optimization and then compare the
results of those methods. After calculating the wing weight by the classical methods,
optimization methods are applied to get weight minimization. Thus, the objective of
the optimization methods is the wing weight. Four different optimization methods are
used in this study. The first method is a graphical optimization method (with one
design parameter) used as the primary method to determine the variables range and
the effect of each spar on the wing weight. The second, third, and fourth optimization
methods (with two design parameters) are searching method, gradient-based
method, and genetic algorithm method respectively. The design parameter chosen
was the flanges ratio, due to its highly participation (20 to 50%) in the wing's total
structure weight.
The optimization algorithms were utilized to analyze the effect of the cross-sectional
geometrical parameters, such as width (Z), height (W) of the flange. The ratio
between these parameters (Z/W) was one of the input data to the stress analysis
process to obtain the minimal cross-section dimensions of the flange under the
allowable stress of the chosen spar material. The spar is made of Aluminum 2024-T4
alloy.
The goal of the optimization is to optimize the cross section parameters of the spar to
withstand the exerted load subjected to the wing, yet with the minimum spar material
with the constraint of keeping that stress within the maximum yield stress of the
material. The results of applying different methods are that the searching method is
the best method in this case of low design variables.