Vol.28 No.6 肖望强等：双压力角非对称齿廓齿轮齿根弯曲应力的有限元分析 ·575。 [3]Deng G.NakanishiT.Bending load capacity enhancement us [习李华敏，韩元莹，王知行.渐开线齿轮的几何原理与计算 ing an asymmetric tooth profile.JSME Int J.2003,46(3): 北京：机械工业出版社，1985 1171 [(吴继泽，王统。齿根过波曲线与齿根应力.北京：国防工业 [4]Difrancesco G.Marini S.Structural analysis of asymmetrical 出版社，1989 teeth:reduction of size and weight.Gear Technol,1997.14 【)龚耀陈式椿，王永洁.渐开线圆柱齿轮强度计算与结构 (5):121 设计.北京：机械工业出版社，1986 Finite element analysis of the tooth root bending stress of an unsymmetric gear with double pressure angles XIAO Wanggiang,LI Wei,LI Mei Mechanical Engineering School,University of Science and Technology Beijing.Beijing 100083.China ABSTRACT This paper deduced the involute gear total tooth profile equations of unsy mmetric teeth with double pressure angles,proposed the calculation fommulas of coordinates and load angle at the upper and lower points of single and double teeth mesh areas,and programmed the relevant parametric programs. Compared with a standard involute gear,the unsy mmetric involute gear could efficiently improve the tooth root bending strength by finite element analysis.Considering the time-variant mesh stiffness,the calculated results demonstrated the change of tooth root bending stress in one engagement period. KEY WORDS unsymmetric gear;gear profile;tooth root bending stress;time-variant mesh stiffness;fi- nite element analy sis (上接第550页) Numerical simulation on temperature field for continuous unidirectional solidifi- cation of NiTi shape memory alloy wire billets HUANG Zuoqin,LIU Xuefeng,XIE Jianx in Materials Science and Engineering School,University of Science and Techmology Beijing Beijing 100083.Chim ABSTRACT The temperature distribution in a crystallizer has important influence on the position and shape of solid-liquid interface during continuous unidirectional solidification.Based on the established three- dimensional physical model,simplified terms specified material parameters in thermal and physical proper- ties,boundary conditions,and the calculation method of heat convection of cooling water,the numerical simulation and analy sis on steady-state temperature field for continuous unidirectional solidificat ion of NiTi shape memory alloy wire billets were proceeded under the condition of different combined parameters using ANSYS finite-element softw are.The results indicate that the NiTi shape memory alloy completely solidifies in the cry stallizer and the solid-liquid interface presents flat under the given model and various parameters which meet the basic requirement of continuous unidirectional solidification. KEY WORDS NiTi shape memory alloy;continuous unidirectio nal solidification;temperature field;finite element simulation[ 3] Deng G, Nakanishi T .Bending load capacity enhancement us￾ing an asymmetric tooth profile.JSME Int J, 2003, 46( 3 ) : 1171 [ 4] Difrancesco G, Marini S .Structural analysis of asymmetrical t eeth:reduction of size and wei gh t.Gear Technol, 1997, 14 ( 5) :121 [ 5] 李华敏, 韩元莹, 王知行.渐开线齿轮的几何原理与计算. 北京:机械工业出版社, 1985 [ 6] 吴继泽, 王统.齿根过渡曲线与齿根应力.北京:国防工业 出版社, 1989 [ 7] 龚 , 陈式椿, 王永洁.渐开线圆柱齿轮强度计算与结构 设计.北京:机械工业出版社, 1986 Finite element analysis of the tooth root bending stress of an unsymmetric gear with double pressure angles X IAO Wangqiang, LI Wei, LI Mei Mechanical Engineering School, University of Science and Technology Beijing, Beijing 100083, China ABSTRACT This paper deduced the involute gear total too th profile equations of unsymmetric teeth w ith double pressure angles, proposed the calculation formulas of coordinates and load angle at the upper and lower points of single and double teeth mesh areas, and prog rammed the relevant parametric programs. Compared with a standard involute gear, the unsymmetric involute gear could efficiently improve the tooth root bending strength by finite element analysis.Considering the time-variant mesh stiffness, the calculated results demonstrated the change of tooth root bending stress in one engagement period . KEY WORDS unsymmetric gear ;gear profile ;tooth root bending stress ;time-variant mesh stiffness ;fi￾nite element analy sis ( 上接第 550 页) Numerical simulation on temperature field for continuous unidirectional solidifi￾cation of NiTi shape memory alloy wire billets HUANG Zuoqin, LIU X uefeng, X IE J ianx in Materials S cience and Engineering S chool, University of Science and Technology Beijing, Beijing 100083, C hina ABSTRACT The temperature distribution in a cry stallizer has important influence on the position and shape of solid-liquid interface during continuous unidirectional solidification .Based on the established three￾dimensional physical model, simplified terms, specified material parameters in thermal and physical proper￾ties, boundary co nditions, and the calculation method of heat convection of cooling w ater, the numerical simulation and analy sis on steady-state temperature field for continuous unidirectional solidification of NiTi shape memory alloy w ire billets w ere proceeded under the co ndition of different combined parameters using ANSYS finite-element softw are.The results indicate that the NiTi shape memory alloy completely solidifies in the cry stallizer and the solid-liquid interface presents flat under the given model and various parameters, w hich meet the basic requirement of continuous unidirectional solidification . KEY WORDS NiTi shape memory alloy ;continuous unidirectio nal solidification ;temperature field ;finite element simulation Vol.28 No.6 肖望强等:双压力角非对称齿廓齿轮齿根弯曲应力的有限元分析 · 575 ·