Analysis of the mechanical behavior of spatially reinforced composites with open holes

The paper deals with the experimental study of mechanical behavior and the common factors of deformation of structural composites in combined use of contactless optical video system and acoustic emission analysis and registration system. The experimental studies were conducted at the electromechanical testing system Instron 5989 in compliance with ASTM 5766 recommendations for the samples of spatially reinforced and fiber-laminated carbon fiber composites with open holes. The preform-based carbon plastic samples with spatially reinforced structure are obtained by 3D-weaving methods. The paper presents the results of mechanical strain tests of open-hole samples. The authors obtained stress and strain diagrams for carbon plastic of various structures and analyzed the evolution of non-homogeneous strain fields on the surface of 3D-reinforced composite samples of the studied structure. They observed the difference in mechanical behavior of spatially reinforced and fiber-laminated carbon fiber composites. The paper presents the images of the samples with the characteristic damages in the area of the opening. Using the acoustic emission signals recording data, the authors obtained the diagrams of dependence of cumulative power, which allowed to observe the diverse nature of damage accumulation for the studied groups of samples.