Study On Transient Thermal Stress Of Graded Composite Plate Under Different Thermodynamic Boundaries

In connection with transient thermal stress problem of FGM in actual work, thispaper made up a new universal model of composite plate with a one-dimensional FGMsandwiched between metal and ceramic. In the three-layer plate, the lower layer is metalTi-6Al-4V, the top layer is ceramic ZrO2, and the middle layer is FGM. Based on thethermodynamics, mechanics, materials science and variational method and so on, wederived the finite element basic equations of temperature field, and compiled practicalcalculation procedures for the structure. By numerical computing and analysis, theconstant physical property transient thermal stress distributions of ECBF compositeplate and ECBC composite plate under the first cooling boundary condition wereinvestigated, and analyzed the influences of porosity, composition distribution shapecoefficient and thickness of FGM layer on the transient thermal stress, and theconstant physical property transient thermal stress distributions of EFBC compositeplate and ECBC composite plate under the third convective heat transfer boundarycondition were investigated, analyzed the influences of porosity A for EFBC compositeplate on the transient thermal stress, and analyzed the influences of convective heattransfer coefficient for ECBC composite plate on the transient thermal stress. The studyresults show as follows:(1) With the thickness of FGM layer is increased from2mm to6mm, the thermalstress and thermal stress gradient of ECBF composite plate and ECBC composite plateboth become smaller gradually, it shows that the FGM thickness increase conducive tothermal stress relaxation of the composite plate.(2) In the process of composition distribution shape coefficient M from0.1to10,when M=1, the transient thermal stress gradient of ECBF composite plate and ECBCcomposite plate is minimum, and the maximum transient thermal stress tended toincrease with increasing values of M, maximum thermal stress difference value is113.21%.(3) With the porosity coefficient is increased from0to3, in the transition regionfrom the pure metal or ceramics to the graded material of the ECBF composite plate andECBC composite plate, distinct turning points appear on the transient thermal stresscurves, this shows that the stress in the composite plate is unreasonable. In the ECBC composite plate, the stress gradient increases near the ceramic area, the thermal stresstended to decrease in FGM layer, maximum thermal stress difference value is83.26%.In the ECBF composite plate, the stress gradient decreases near the ceramic area,transient thermal stress tended to decrease, maximum thermal stress difference value is81.94%.(4) With the porosity coefficient A is increased from0to3, in the EFBC compositeplate, the thermal stress increases near the metal area, maximum thermal stressdifference value is205.27%. The stress gradient increases in FGM layer, and when A=1,2,3, in the transition region from the pure metal or ceramics to the graded material,distinct turning points appear on the transient thermal stress curves, this shows that thestress in the composite plate is unreasonable.(5) With the convective heat transfer coefficient is increased from0to3, thermalstress gradient increases in the ECBC composite plate, the thermal stress increasesobviously near the ceramic area, maximum thermal stress difference value is2.4127695GPa.The inferred formula and analysis of the results in this paper provide theory forstudying of two-dimensional metal-FGM-ceramic composite plate and their practicalapplication.