Hi Everyone,

I was hoping someone might be able to assist me in being able to extract data from a manufacturer's provided values for use in an elastic stiffness matrix of an anisotropic material. The material being investigated is a composite wood made into an annular plate, layered vertically. The main issue is that the data itself is given in rather general terms and on, is own not complete for a fully accurate model.



Using the attached compliance matrix image (above), one can see the general regions for elastic compliance. The simplest version that could illustrate the differences experienced by directionality would be a transversely isotropic model. (I know some people refer to this as Orthotropic when dealing with lamina and are not using the radial direction, instead of 3 mutually orthogonal planes of symmetry.) However, since the wood should provide shear-shear and shear-extension coupling, a modified Monoclinic stiffness matrix with a single plane of isotropic symmetry would be an ideal end-goal.

For mechanical data, I have only been provided with the following from a data sheet [as labeled] in addition to the general radii and thickness of the annular plate:

• Modulus of Elasticity in Flexion (Perpendicular)
• Compressive Strength @ Room Temperature (Perpendicular)
• Compressive Strength @ Room Temperature (Parallel)
• Tensile Strength (Parallel)
• Flexural Strength (Perpendicular and parallel)
• Impact Strength @ Room Temperature (Perpendicular)
• Impact Strength @ Room Temperature (Parallel)

If possible I would like to avoid having to do in-house testing of this purchased to determine directional Poisson effects due to the cost and time for proper equipment. The modulus of elasticity in the perpendicular direction is helpful. However, to do just a traversely isotropic model, 5 independant constants are needed:

• E_sym_plane
• E_orthogonal (given)
• Poisson's ratio in the symmetry plane
• Poisson's ratio between the orthogonal and symmetry planes
• Shear modulus between the symmetry plane and the orthogonal plane.

Aside from contacting the manufacturer and asking for test data or any additional information they may have, does anyone have some suggestions or ideas of where to proceed?

Also, in relation to the Flexural Strength, what kind of unique information for this type of approach can be extracted? If the material was homogenous, it would be the same as the tensile strength. I know that this is obtained via a 3-Point test, where a moment on each side is created with a shear force applied in the center. Since this test is for measuring a bending pressure maximum, be useful to extract data for shear-shear or shear-extension coupling in an elastic stiffness matrix? If so, how would this be done?

Thank you all for any help you may be able to offer.