Analysis On The Basic Mechanical Properties Of 2.5D Fabric And Composite Object

2.5D fabric is a kind of special 3D fabric. It has better mechanical performance in the thickness direction. 2.5D fabric has received wide attention in the aerospace field as well as other related fields and it has good application prospects. In this paper, 2.5D radial enhanced and 2.5D braided fabric composites were analyzed. The basic mechanical properties of the structure were analyzed through theoretical analysis and experimental testing.The research background as well as its significance is introduced respectively in the first section of this paper. The mechanical properties of the fabric, micromechanical model as well as forming process are summarized.In the second chapter, the microstructure of the 2.5D fabric is analyzed. The section shapes of yarn and binder direction are observed which is used to determine the corresponding geometric model finally. Theoretical analysis of the 2.5D fabric based on the established geometric model is conducted. First, the macroscopic elastic modulus of fabric is calculated by the method of energy equivalent. Then, the thickness and width of the fabric are analyzed according to the deformation of the yarn. Finally, the relationship between elastic modulus and orientation angle as well as the number of the 2.5D fabric is obtained by changing the orientation angle and the number of layers.In the third chapter, the deformation behavior of 2.5D fabric is analyzed. Tensile strain rate and residual deformation rate were analyzed by tensile test, from which we can get the tensile deformation of fabric under tensile loading. Secondly, the transformation in thickness of the fabric is analyzed and the change in thickness of fabric in the process of radial tension is obtained.In the fourth chapter, 2.5D woven composites were prepared by impregnation method and RTM composite method. According to the technological requirements, a set of mould is designed and then the process is determined according to the process conditions. The C scan of the composite was carried out at last which could find out whether the specimen contain defects. The comparison of the two kinds of technology is carried out by scanning results from which we can get the advantages and disadvantages.In the fifth chapter, the mechanical properties of 2.5D woven composites are analyzed. Firstly, the fiber volume content of 2.5D woven composites was calculated by theoretical calculation, then, the tensile and compression test as well as three point bending tests of the composite were carried out, the failu re mode and the test results were analyzed. At last, we can get the conclusion that the mechanical properties of the products prepared by the two different methods have different and the effect of pre-deformation on the mechanical properties of the structure.