Q] is a reduced

stiffness matrix obtained by the rotation of the original

stiffness matrix Q:

E] is the initial

stiffness matrix of the experimental part.

In general, a cohesive element can be differentiated to a continuum element by a reduced

stiffness matrix based on reduced sectional stresses, Figure 2.

The

stiffness matrix of orthotropic composite materials is usually written as 3*3 matrix in the following:

r] are the mass matrix,

stiffness matrix, and exciting force vector based on generalized coordinate [x.

As a continuum material model, the homogenization between the resin matrix and the woven fabric fibers is performed when overall

stiffness matrix of each element is assembled.

where u is the displacement vector, M is the mass matrix, C is the damping matrix which includes the friction effect, K is the

stiffness matrix, and Q is the external load.

Having known mode shape matrix and

stiffness matrix the MSE values is evaluated.

The element

stiffness matrix is integrated analytically with the advantage of fast stiffness computation.

Since the in-plane rotational degrees of freedom are not included, the null values for the in-plane rotational degrees of freedom will lead to singularity in structure

stiffness matrix if all the elements are coplanar.

The SPF/SPS biocomposite consists of low

stiffness matrix and high stiffness fibres, thus by increasing the weight percentage of fibres increases the stiffness of the biocomposites.

The

stiffness matrix depending onto the object displacement the solution obtained using the finite element method (FEM), differs from the real value, and in some cases may even extend beyond the task defining domain (Fig.