A random field representation of the horizontal density distribution in partially oriented flakeboard mats was investigated. The orientation of flakes can be characterized by both the Von Mises distribution and the uniform distribution within a range of angles. Theoretical models of the correlation coefficients of any two points simultaneously covered by one flake, variance functions of local density, characteristic area of the correlation, and the degree of orientation were developed. Results indicate that the concentration factor k = 700 is sufficiently large to represent a perfectly aligned flake arrangement in oriented flakeboards based on the Von Mises distribution. The correlation coefficients of two points in a mat have a lower bound (random case) and an upper bound (perfectly aligned) in both Von Mises and uniform distributions. The variance is considerably reduced when the sampling zone size is within the length of flake. Based on the concept of characteristic area, where the minimum characteristic area is the area of a flake and the maximum characteristic area is approximate to the square of flake length, the degree of orientation in a panel can be represented as a function of characteristic area. This value is found to be very close to the percent alignment definition.

A paper prepared from this chapter has been submitted for publication in the Wood Science and Technology, 1999.