homogeneous

the material has the same composition at every point

 

isotropic

the properties are the same in all directions

source

 

transversely isotropic

the properties in a particular direction are the same throughout the material and the properties in all directions perpendicular to that direction are the same

photo by Jeff Thomas, 2003

photo by Jeff Thomas, 2003

 

orthotropic

there are at least 2 orthogonal planes of symmetry, where material properties are independent of direction within each plane

Koch, P. 1972a. Utilization of the southern pines. I. The raw material. USDA Forest Service Agricultural Handbook No. 420. 733 pp. Koch, P. 1972b. Utilization of the southern pines. II. The raw material. USDA Forest Service Agricultural Handbook No. 420. 926 pp.

 

anisotropic

the properties differ in all directions

taken by Mike Crites, Jose Soto, & Jeff Thomas, October 1997