Non-fourier Heat Conduction And Thermal Shock Fracture Resrarch Of Layered Materials

Fourier law of heat conduction is a heat diffusion behavior that the velocity ofspread is infinite. As for the quasi-equilibrium hypothesis, has been widely applied inpractical engineering field. But with the development of science and technology, nanoand micro heat conduction materials appears, in the thermal shock environment ofstrong transient heat conduction, Classical Fourier heat conduction law is not applicable.Therefore the nonclassical heat conduction law became the research hotspot. In thepractical application, Ceramic/metal structure material as the main form of thermalprotection materials, Due to the material itself has the inevitable defects or cracks,Combined with the non-classical shock environment of strong transient thermal,Material may cause fracture failure due to fatigue damage and crack propagation.Therefore, research thermal shock fracture of inhomogeneous material in thenon-Fourier heat conduction environment have greater practical significance. This papermainly studied temperature field, stress field and thermal impact fracture problems withcenter crack of one-dimensional semi-infinite laminated material under the non Fourierheat conduction environment.Because the properties of laminated material discontinuities, so that thermalmismatch has been generated in thermal shock environment, is likely to encourageinternal crack propagation and cause fracture failure, so with the wide application ofnon Fourier heat conduction effect. Study on thermal shock of heterogeneous materialsfracture is very important. So far, in inhomogeneous material medium, Study on thenon-Fourier heat conduction thermal shock fracture, and solving the non-classical stressintensity factor of the near center crack tip is still blank.This paper not only solve the temperature field and stress field of one-dimensionalsemi-infinite laminates, but also analysis the non-classical fracture strength problem ofthe laminate with a central crack from the angle of fracture mechanics. This papermainly includes three aspects:(1) Based on the classical heat conduction equation, the non-fourier heatconduction equations are derived by using the backward difference scheme of finite difference method, and obtained numerical solution of heat conduction equation, andthe numerical results are discussed. Finally obtain the analytic solution of heatconduction equation in homogeneous materials by using the standard method ofseparation of variables, through comparative analysis of numerical solution and analyticsolution, determine the the stability of backward difference scheme and the accuracy ofresults.(2) Using the linear thermal stress theory, based on the known distribution oftemperature field, then according to the boundary condition, solved the distribution oflaminated material internal thermal stress field. Finally discuss the influenced ofthermal stress field distribution by laminate relaxation time, thermal diffusivity andcoating thickness.(3) Through establishing finite element model of laminate with central crack. Then,on the basis of laminate internal thermal stress field distribution, to solve the thermalstress field of near crack tip by finite element software. Through use the stressextrapolation method to solve the non-classical stress intensity factor curve of the nearcrack tip. Finally, analysis and discussion of the crack size, coating thickness effect onnon-classical stress intensity factor.