Effects of ply thickness deviation and ply angle misalignment on the surface accuracy of CFRP laminates

Abstract

This study examines two factors that affect the surface accuracy of symmetric carbon-fibre-reinforced plastic (CFRP) laminates: ply angle misalignment and ply thickness deviation. First, based on classic laminate theory, theoretical expressions for the effects of these factors are deduced. Then, COMSOL (FEM software) is used to analyse the relationship between these factors and the surface accuracy, and Zernike polynomials are used to fit the surface deformation of the CFRP laminates. It proves that ply angle misalignment and ply thickness deviation can cause astigmatic and power aberrations. Based on the integral constraint method in the form of Lagrangian multipliers, the rigid body displacement problem of the free thermal expansion simulation of CFRP laminates has been solved. Finally, three groups of experimental tests show that ply thickness deviation does occur. A ZYGO interferometer is used to observe the surface accuracy of the laminates, and it shows that astigmatism is the dominant aberration.