Braided angle measurement technique for three-dimensional braided composite material preform using mathematical morphology and image texture

This paper describes a new measuring algorithm for estimating the exterior average braided angle of a three-dimensional (3-D) braided composite material preform] based on image texture. In this project, an advanced filtered algorithm for an image of a 3-D braided composite material preform is developed on the basis of mathematical morphology. Median filter algorithms for mathematical morphology are applied in the system. The polar spectrum and main properties are investigated in the paper. Theory shows that a rotated texture's polar spectrum is an approximate translation of the unrotated texture's polar spectrum, and that the degree of each translation approximates to the corresponding rotation of the surface. The system was tested on both carbon and glass fibre preforms. We have obtained very encouraging experimental results, which show that the proposed method is feasible. So far, the research is a new development for measuring 3-D braided composite material preforms. The work will lay the foundation for establishing a test standard for 3-D braided composite material in China.