**4. Stress behavior simulation of composite materials with natural fibers**

All major software platforms for Computer Aided Design and Finite Element Method Simulations allow the study of composites with natural fibers via the Composite Shell implementation. There are three types of composite options to define the arrangement of plies, thicknesses, material properties, and orientations, see **Figure 7**.


**Figure 7.** *3D CAD models of symmetric and Sandwich composites.*

mass of the composite and has a high shear modulus of elasticity to resist the sliding of the skins.

Composite shells are used for structural members with weight savings required. The shells offer improved fatigue strength, corrosion resistance, and thermal conductivity. In the Shell Property Manager of such applications it is possible to define symmetric, asymmetric or sandwich composites with a number of layers up to 50. The Property Manager also allows users to set different thicknesses, material orientations and same or different material properties for each ply.

Composite laminates are special orthotropic materials that are modeled as single surfaces with several layers of orthotropic materials. A cross-ply sisal fiberreinforced polymer is an example of a composite laminate with orthotropic material properties for each ply. A rock is an example of an orthotropic material that does not qualify as a composite. Notable differences between a composite laminate and an orthotropic material body:

Composite Laminate:

• Uses a laminated shell element formulation. In addition to other stress results, displays interlaminar shear stress between two adjacent plies. Delamination can occur between two plies with high stress values.

• Uses these unique failure criteria: Tsai-Hill, Tsai-Wu and Maximum Stress

Orthotropic Material Body:

