Authors: Yang Jian Xu, Ling Ling Wang, Hai Yang Du

Abstract: The steady heat conduction problems under linear temperature load on upper surface in an Al1100/Ti-6Al-4V/SiC 2D-FGM plane plate are analyzed by the FEM. When the variation of the material composition in y-direction is linear, the plane temperature distributions with the changes of composition shape distribution coefficient mx and porosity coefficient Ax in x-direction are obtained. The results show that when mx<0.1, the temperature curve surface is upward convex. The smaller mx is, the bigger relative temperature gradient on the left side of the plate is. When mx>1.0, the temperature curve surface has smaller upward convex trend and becomes downward convex surface gradually with the increasing of the mx (except at =1). The bigger mx is, the bigger relative temperature gradient near the right ceramic side of the plate is. By comparison with the results of an Al1100/SiC 1D-FGM plate, in the 2D-FGM plane plate, when mx=0.5, the maximum value of the temperature difference near metal side increases by 15.6%, but the value near ceramic side reduces by 53%. The temperature curve surface has more obvious variation with the increasing of the Ax in the plate, especially it is when =0.3~0.5 and =0.2~0.5, the changes of the temperature difference value reach the maximum, and compared with Ax=0.0, the value of Ax=3.99 increases by 138.6% at =0.35 and =0.4. The results provide more comprehensive and concrete basis of calculation and the further analysis of thermal stress for the design and optimization of the 2D-FGM plane plate.

235

Authors: Yang Jian Xu, Hai Yang Du, Dai Hui Tu

Abstract: A NFE model is constructed to analyze the convective heat transfer steady thermal stress in a ZrO2/FGM/Ti-6Al-4V composite ECBF plate with temperature-dependent material properties. From numerical calculation, when , T0=300K, Ta=550K and Tb=1800K, the stress distributions in the plate were obtained. The results are as follows. With the increase of the FGM gradient layer thickness, the stress distribution in the composite plate is more reasonable. With the increase of M, the thermal stress change increases obviously in metal and ceramic layers, and the stress on the ceramic surface reduces. With the increase of porosity, the change of stress at the bonding interfaces increases, and the tensile stress on the surface of ceramics reaches the maximum. Compared with , when , the stress on the metal surface reduces by 25.1%, and the maximum compressive stress on the surface of ceramics increases about 1.2GPa. Compared with the nongraded two-layered ceramic/metal composite plate, the thermal stress of ZrO2/FGM/Ti-6Al -4V composite ECBF plate is very gentle. When we consider the temperature dependency of the material properties, the thermal stress in graded three-layered composite plate becomes small obviously. The results provide the foundations of theoretical calculation for the design and application of the composite plate.

158

Authors: Yang Jian Xu, Ling Ling Wang, Li Wen Dong

Abstract: The steady thermal stress problems under linear temperature load on upper surface in an Al1100/Ti-6Al-4V/SiC 2D-FGM plane four-side clamped plate are analyzed by the FEM. When the variation of the material composition in y-direction is linear, the plane thermal stress distributions with the changes of composition shape distribution coefficient mx and porosity coefficient Ax in x-direction are obtained. The results show that compressive stresses of the metal side reduce and the compressive stresses increase on the ceramic side with the increasing of the mx. Except for lower surface, when mx =0.5, the thermal stress values of the 2D-FGM plane plate are smaller than those of the 1D-FGM plate. Compared with the maximum thermal stress value of the 1D-FGM plate, that of the 2D-FGM plane plate reduces by 815MPa. The thermal stress curve surface has more and more obvious convex trend and has smaller thermal stress gradient with the increasing of the Ax, especially it is when =0.1~0.5, =0.2~0.5, and other places have no variation. By comparison with the minimum thermal stress of Ax=0.0, that of Ax=3.99 reduces by 47.3% at =0.3. The results provide more comprehensive and concrete foundation of calculation for design and optimization of the 2D-FGM plane plate.

48

Authors: Yang Jian Xu, Dai Hui Tu, Jian Hui Jia

Abstract: The steady thermal stress distributions and effect factors in a ceramic/FGM/metal composite EFBC plate with temperature-dependent material properties during heating process were investigated by the NFEM and the Sinpson method. From numerical calculation, when T0=Ta=300K and Tb=1 300K, the stress distributions in the plate were obtained. The results are as follows. With the increase of the FGM layer thickness, the stress distribution in the composite plate is more reasonable. Compared with M=0.1, when M=10, the compressive stress on the ceramic surface increases by 9.0%, and the tensile stress on the metal surface reduces by 17.9%. With the increase of FGM layer porosity, the variations of thermal stress curves become big. Compared with A=0, when A=3.99, the tensile stress on the metal surface increases by 65.5%, and the maximum compressive stress on the surface of ceramics reduces by 27.5%. Compared with the results of constant material properties, when we consider the temperature dependency of the material properties, the maximum tensile stress on the surface of metal in the plate reduces by 30.1%, and the maximum compressive stress on the surface of ceramics in the plate reduces by 9.49%. Compared with the nongraded two-layered plate, the tensile stress at middle of the graded three-layered composite EFBC plate reduces by 53.5%. When T0=300K, Ta=700K, compared with Tb=1 050K, when Tb=1 800K, the tensile stress on the surface of metal increases 563MPa, and the maximum compressive stress on the surface of ceramics increases 7.24 times.

231

Authors: Dai Hui Tu, Yang Jian Xu, Xiao Li Zhou

Abstract: The steady thermal stress distributions and effect factors in a ceramic/FGM/metal composite EFBC plate considered constant material properties under convective heat transfer boundary were investigated by the FEM and the Sinpson method. From numerical calculation, when , T0=300K, Ta=400K and Tb=1 400K, the stress distributions in the plate were obtained. The results are as follows. With the increase of the FGM layer thickness, the stress distribution in the composite plate is more reasonable. Compared with M=0.2, when M=5, the compressive stress on the ceramic surface reduces by 10.2%, and the tensile stress on the metal surface reduces by 21.7%. With the increase of A, the variations of thermal stress curves become big. Compared with A=0, when A=3.99, the tensile stress on the metal surface increases by 198.0%, and the maximum compressive stress on the surface of ceramics increases by 66.0%. Compared with the mutation of thermal stress at the cohesive interface of ceramic / metal two-layered composite plate, the thermal stress of ceramic/FGM/metal composite plate is very gentle. Compared with , when , the maximum tensile stress on the metal surface increases 1.44 times, and the maximum compressive stress on the surface of ceramics increases 1.50 times. The results provide the foundations of theoretical calculation for the design and application of the composite plate.

239

Authors: Yang Jian Xu, Dai Hui Tu

Abstract: The steady temperature distributions in a ceramic / metal composite FGM plate with temperature-dependent material properties during heating process were investigated by the NFEM. From numerical calculation, when T0=300K, Ta=650K and Tb=1 700K, the temperature distributions in the composite FGM plate were obtained. The results are as follows. With the increase of the FGM gradient layer thickness and when M=1, the temperature distributions in the composite plate are more reasonable. With the increase of porosity, the variations of the temperature curve become big obviously, and there is an abrupt change for the temperature at =0.5, its value is about 917K, but the temperature curve is gentle and smooth at the bonding interfaces of the three-layered composite FGM plate. Compared with the nongraded two-layered ceramic/metal composite plate, the temperature of the ZrO2/FGM/Ti-6Al-4V composite plate is very gentle. When the temperature dependency of the material properties was considered, the temperature in graded three-layered composite FGM plate becomes small obviously. The results provide the foundations of theoretical calculation and the further analysis of thermal stress for the design and application of the composite plate.

1147

Authors: Dai Hui Tu, Yang Jian Xu, Jian Hui Jia

Abstract: The steady thermal stress distributions and effect factors in a ZrO2/FGM/Ti-6Al-4V composite ECBC plate with temperature-dependent material properties under convective heat transfer boundary were investigated by the NFEM and the Sinpson method. From numerical calculation, when , T0=300K, Ta=350K and Tb=1 750K, the thermal stress distributions in the composite FGM plate were obtained. The results are as follows. With the increase of the FGM gradient layer thickness and when M=1, the temperature distributions in the composite plate are more reasonable. With the increase of the FGM gradient layer M, the thermal stresses on the ceramic surface tend toward reduction, and compared with the thermal stress of M=0.2, the thermal stress of M =5 reduces by 17.8%. When we take into account the effect of temperature-dependent material properties, compared with the results of constant material properties, the maximum compressive stress on the surface of metal reduces by 74.2%, and the maximum compressive stress on the surface of ceramics reduces by 45.3%. With the increase of FGM layer porosity P, the change of stress at the bonding interface of the three-layered plate increases, and the stress curves appear peak values. Compared with A=0, when A=3.99, the compressive thermal stress on the metal surface reduces by 42.0%, and the compressive thermal stress on the ceramic surface increases by 154.7%. Compared with the nongraded two-layered ceramic/metal composite plate, the thermal stress of the ZrO2/FGM/ Ti-6Al-4V composite plate is very gentle. Compared with , when , the maximum compressive stress on the surface of metal reduces by 49.98%, and the maximum compressive stress on the surface of ceramics increases by 182.3%. The results provide the foundations of theoretical calculation for the design and application of the composite plate.

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