Analysis Of Microscopic Failure Mechanism And Numerical Simulation Of Damage Of CMCs Bolt

Ceramic Matrix Composite(CMCs)have been widely used in the fields of astronautics and aeronautics,due to their excellent mechanical properties at high temperature.Bolt joint is the most common form of mechanical joints in CMCs structure.How to ensure that the structure of bolt joint does not fail during work process is an important subject in the field of CMCs structural design.CMCs bolt has complex meso-structure whose failure is closely related to the meso-structure.However,the current research on the failure of CMCs bolt does not fully consider the influence of the meso-structure,and can not accurately predict the failure behavior of CMCs bolt.In this paper,the mesoscopic failure mechanism of CMCs bolt has been researched by means of experiments and numerical calculations,and the numerical simulation method of meso-damage has been preformed.It has important engineering significance and academic value.Firstly,the internal structure of CMCs bolt has been observed through X-ray computer tomography(XCT)technology.On this basis,the mesoscopic finite element model of CMCs bolt has been established,and the failure analysis of CMCs bolt has been realized by progressive damage model.The failure load,failure mode and damage evolutional process of CMCs bolt under tensile load have been predicted.Then the axial tensile experiment of CMCs bolt at room temperature was carried out.The displacement data were collected by digital image correlation(DIC)technology,and the failure fracture morphology of CMCs bolt has been observed by scanning electron microscope to obtain the load-displacement curve and macroscopic failure mode of CMCs bolt under tensile load.According to the comparison between the results of simulation and experiment,the mesoscopic failure mechanism of CMCs bolt has been revealed.Finally,according to the predicted failure load,the maximum and minimum tightening torque of the CMCs bolt has been calculated.The bolt of suitable strength has been advised for the joint structure on the basis of the tightening torque range.