Simcenter 3D Laminate Composites (LC) allows you to easily define laminates, assign them to 2D or 3D meshes of complex geometries, and post-process composite failure metrics. For simple parts like test coupons, creating a FEM is not required, as LC allows you to verify the ability of your laminate to withstand the following loading conditions:
- Membrane forces
- Bending moments
- Transverse shear forces
- Temperature loads
In this example, we will determine the loads required to produce first-ply failure in a 4 point bending test coupon as per ASTM D7264. We will compare the LC results with those of a shell element FEM with appropriate boundary conditions.
Laminated strip under four-point bending
Figure 1: Laminate strip under three-point bending
A cross-ply laminate with [0/90/0/90/0/90/0] layup is specified with the center ply being four times as thick as the others. With such a lay-up, the bending moment is reacted more uniformly across the section. A model, with appropriate boundary conditions, is used and predictions are obtained using laminated shell elements.
Figure 2: A laminate test specimen under four point bending
The initial guess at the failure bending moment is 1250 Nmm. The applied moment per unit length is 1250 N.mm/10mm = 125 N
The applied load P = -4M/L = -(4*1250Nmm)/50mm= -100 N.
1. Determine failure load
Create a new empty FEM, by clicking NEW command.
Figure 3: Create a new FEM
First, we define the material properties to be used in the laminate definition.
Go to Home tab and under the Properties group click on Manage Materials.
Figure 4: Manage Materials
In the Manage Materials dialog, set the type to Orthotropic and click on Create.
Figure 5: Define a new orthotropic material
Then define mechanical and strength properties as shown in Figure 6 and Figure 7.
Figure 6: Define material mechanical properties
Figure 7: Define material strength properties
To define the laminate, go to NX’s Laminates tab and click the Laminate Physical Property button.
Figure 8: Create a laminate physical property
In the laminate modeler, select Import Layup Using Shorthand Format button to quickly define the layup.
Figure 9: Import Layup Using Shorthand Format button
Figure 10: Shorthand format to define a layup
In the Laminate Modeler dialog, set the output format to PCOMP, and the Ply Failure Theory to Tsai-Wu. Click OK to close the dialog.
Figure 11: A symmetric quasi-isotropic laminate [0/90/0/90/0/90/0]
In the Laminate Modeler, under the Validation group, click the Analyze Laminate Strength button.