Crack Propagation Of Weak Interface Of Continuous Ceramic Matrix Composites

Continuous fiber reinforced ceramic matrix composites(CFCC)have many advantages in the application of aero-engine hot components.Studies on mechanical properties of CFCC have received more and more attentions.Because the interfacial strength of most CFCC are relatively weak,the fracture processes of CFCC are more complicated than traditional composite materials.Understanding the fracture processes and the influence factors of fracture processes are important to further study and apply CFCC.Firstly,the defect in CFCC matrix is studied.It is simplified into lip defect and then the stress intensity factor(SIF)of lip defect is obtained using the theory of complex function and conformal mapping.Besides,the influences of geometric parameters of defect on the SIF are analyzed,which lay a foundation for subsequent studies on CFCC.Next,the transverse mechanical properties of CFCC which contain weak interface are analyzed by finite element method.The simulation for the representative volume element(RVE)is finished to study the influence factors of the fracture processes,especially the influence of the weak interface.And then,the stress-strain curves are analyzed.Next,the longitudinal mechanical properties are studied,simulations for three dimension RVE with weak interface are finished,which clearly show the fracture processes of CFCC under longitudinal tensile,then the stress-strain curves which are obviously bilinear are gotten.Finally,tensile experiments for C/SiC composites are performed and the stress-strain curves are gotten,which give a verification for the simulations.Besides,the microtopography of crack and interface debond are observed by using Scanning Electron Microscopy.