Effect of lay-up configuration on the microwave absorption properties of carbon fiber reinforced polymer composite materials

Multidirectional carbon fiber reinforced polymer (CFRP) composites, stacked by multiple layers of unidirectional prepregs, are generally considered to be microwave reflective, but we have found that it is not always the case. In this paper, the microwave response of many CFRP laminates has been investigated, considering the effect of the fiber orientation and the laminate thickness. An analytical model was developed to establish the relationship between the lay-up configuration and the effective impedance of composite laminates. The result indicated that if carbon fibers inside the headmost layer(s) are parallel to the incident electric field, the material will reflect the microwave power regardless of the subsequent fiber orientation and laminate thickness, due to the high conductivity of carbon fibers in the axial direction. Otherwise, the response of the CFRP laminates will strongly associate with the position of its internal cross-ply and the laminate thickness, as they have a significant influence on the impedance of the laminate. When the position of the cross-ply is far from the surface radiated by microwave, the multidirectional CFRP laminate can be changed to microwave absorbers, because it has a relatively matched impedance with air. The findings in this paper may be applied to design lay-up configurations of CFRP laminates for a specific microwave performance, besides mechanical properties.

Automated summary

The microwave response of multidirectional CFRP laminates is influenced by fiber orientation, laminate thickness, and positioning of internal cross-ply. When carbon fibers are parallel to the incident electric field, the material reflects microwave power, while other configurations can result in either reflection or absorption depending on the impedance matching with air.