Memetic Computing Applied to the Design of Composite Materials and Structures

Table 2

Fitness equation coefficients.

Coefficient	Description
	Longitudinal coefficient along the direction of the fibres. It is a real value indicating the relationship between longitudinal stress in the direction of the fibres and the breakage stress in that direction. As the direction of the fibres is that of most resistance, it is of interest that this ratio is as high as possible. For this reason, it is in the numerator. has been empirically determined as 2.; where the stress is either tensile or compressive and the sum applies to the laminas that do not break.
	Longitudinal coefficient perpendicular to the direction of the fibres. It is a real value that indicates the relationship between the longitudinal stress perpendicular to the fibres and the breakage stress in that direction. As the direction which is perpendicular to the fibres is that of least resistance, it is of interest that this ratio is as small as possible. For this reason it is in the denominator.; where the stress is either tensile or compressive and the sum applies to all the laminas.
	Shear coefficient. It is a real value that indicates the relationship between the shear stress in the plane and the maximum stress that can be tolerated in that plane. As the lamina has low resistance to these stresses, it is of interest that this ratio is as small as possible. For this reason it is in the denominator. The sum applies to all the laminas.
	Coefficient that indicates whether the number of adjacent layers with the same orientation is less than or equal to four or greater than four It is in the denominator so as to heavily penalize this second possibility. Its values have been empirically determined.
	Fiber volume fraction of the laminate. As this value should tend towards small values that are more advantageous economically, it is placed in the denominator where small values will have a positive effect.
	Product of the number of laminas and its thickness (expressed in metres). has been empirically determined as 12.
	It indicates the number of layers that break , and is in the denominator in order to penalize such event. has been empirically determined as 4.