Analysis On Vibration Characteristics And Crack Growth Of FGM Shell Under Thermal Environment

This paper takes function grade material(FGM) shell as study object, the physical characteristics of FGM have been studied by the structural dynamic model that is set up by the finite element stratify method. And the impacts of thermal environmental on the dynamic characteristics of FGM shell and the crack propagation law of FGM shell are discussed.Firstly, the change law of physical characteristics of FGM along with the change of temperature is analyzed, the impact of linear change of initial stiffness that introduced by the change of physical characteristic on the vibration characteristics of FGM shell is discussed. Then, nonlinear deformation of FGM shell that introduced by uniform and linear temperature thermal environment, and the thermal stress that introduced by temperature grade are studied. The change of stiffness and geometry parameter that resulted by thermal stress and thermal deformation is analyzed too. Combined with initial stiffness, initial displacement and thermal stress, plus the geometry boundary condition, external load and physical parameter, the vibration property of FGM shell under thermal mechanical environmental is probed. The cracked FGM shell is taken as the study object to study the crack growth law and its fatigue life in the end. Under the given crack position and crack size, the crack growth path is imitated under the uniform temperature field and the first mode thermal mechanical coupling loading.According to the case studies, the change law of FGM physical characteristics under the uniform and linear temperature field with different volume fracture is obtained. The impacts of thermal physical characteristic and the thermal stress under uniform temperature, and the thermal stress coupling effect on the vibration proper of FGM shell is obtained.Results indicate that the physical characteristic of FGM is changed series under thermal environment. The change of physical characteristics, especially the change of elastic modulus has obvious influence on the vibration characteristics of FGM shell. Under the condition of thermal stress coupling, the modal frequency is bigger than the modal frequency under the condition that only considers the effect of temperature on the physical characteristics. And the higher the temperature, the bigger the gap between the two curves. Thermal stress that is produced by the uniform temperature plays the main role function.