塑料齿轮硬度的数字分析外文文献翻译、中英文翻译

Numerical Simulation of Residual Stress in Injection MoldingXI Guo-dong, ZHOU Hua-min, LI De-qun (State Key Laboratory of Mold &Die Technology, Huazhong University of Science and Technology, Wuhan 430074, China)Abstract: Distribution and history of residual stress in plaque-like geometry aresimulated based on linear thermoviscoelastic model, to explore the mechanics and evolution of residual stress in injection molding process. Results show that the residual stress distribution through thickness is almost the same along flow path and the stress value near the end is a litter higher than that near the gate.CLC number: TQ 320.66；O 345 Document code: A Article ID:1003-4951(2006)01-0017-07Keywords: injection molding; residual stress; numerical simulation; thermoviscoelastic1 IntroductionInjection molding is a flexible production technique for the manufacturing of polymer product. A typical injection molding process consists of four stages: filling, packing, cooling and ejection of product. During these processes, residual stress is produced due to high pressure and cooling, which induce the warpage and shrinkage of product. To make the product with high precision, it is important to simulate the pressure and thermal effect induced residual stress in the processes. Residual stress of injection molding has received more and more attention recently. Many researchers15 calculated the residual stress and shrinkage in the process by using different models.In general, the study of residual stress is focused on the theoretical analysis with an isolated model. It does not take into account the specifics of injection molding and correlate with the packing and cooling analysis. In this study, distribution and history of residual stress in plaque-like geometry is simulated based on linear thermoviscoelastic model, where the effects of pressure, thermal history and stress relaxation are jointly investigated.The numerical calculation model is built by finite difference method in time duration with layered discretization along thickness and under the specified boundary conditions. The developed simulation system is used to calculate the residual stress of typical injection molded parts.2 Model Problem2.1 Linear Thermoviscoelastic ModelTemperature and pressure induced stresses arise from inhomogeneous cooling of the part in combination with the hydrostatic pressure. For cooling, the relaxation time increases and becomes comparable to the filling and packing time; therefore accurate prediction of thermal stress would require viscoelastic constitutive equations.But within the limit of infinitesimal strains variation the behavior of viscoelastic material is well described by the theory of linear viscoelasticity. Most injection mould products are very thin, we can take the flow direction as 1-dimensional and the local thickness direction as the 3-direction and build the local coordinates. The total stress tensor ij can be split into a hydrostatic pressure h P and an extra stress part ij 6Where G1 is bulk relaxation function, G2 is shear relaxation function, th is thermal strain, mis spherical strain tensor,ij extra strain tensor and (t) is the material time.2.2 Basic Assumptions and Boundary ConditionsFor simplifying the calculation of thermally and pressure induced stress in the injection molding process, the following assumptions are made:(1) We take the flow direction as the 1-direction and the local thickness direction as the 3-direction and build the local coordinates; (2) While in the mold, the material is locally constrained in the in-plane directions by three dimensional features of the part (bosses, ribs and other walls), so the in-plane strain is assumed to be equal to 0; (3) The normal stress 33 is constant in the thickness direction of the product and equals the reverse of cavity pressure; (4) As long as the cavity pressure is non-zero ( 0 33 对称2 补偿2 对称4 补偿 4.Fig. 6模拟硬度实验硬度 这说明当齿轮齿厚增加时，齿扭曲变形变大, , 因而硬度变低. 当齿厚是同一的, 对称齿轮有更高的硬度比垂直齿轮. 这是因为在垂直齿轮,凹的部分不断地在厚的一个边查找, 然而对称齿轮, 它在厚度的两边查找, 因此积聚的变形前者大于后者，因此后者的硬度要大。此外, 对于垂直齿轮, 敲击力有两个相对的方向对驱动齿.，但是模拟结果表示相对位置在凹处的中间对齿轮硬度和敲击力无关。4实验性结果： 图6表明这仿真硬度和实验硬度两者之间的相关关系：当MU = 0 .15, R = 1 .1, 和E = 2 .744GPa 。从这个图, 在这五齿轮之中,在模仿结果和实验结果之间能看这高线性。这线性核实, 模仿是正确的。但是模仿硬度比实验价值高级; 有一个线性区别在他们之间。它可能是因为物质参量在模仿是不够准确的; 有限元素算法 4 ; 塑料黏度没有被考虑在模拟中；在模仿模型中的在齿轮齿根上的缺点不是足够准确的。5总结：对预测齿轮硬度由建立3-D 模型和使用有限元的方法是可行的。(2) 摩擦参量MU和R两个影响齿轮硬度。当MU增加时，滑动摩擦困难也增加, 则能提高齿轮硬度。但是如果摩擦系数是太大,对传动的提高有不好的影响。增长的R1 可能帮助提高齿轮硬度, 但R2对齿轮硬度影响甚小。(3)当齿轮厚度相同是，由于积聚的变形，垂直齿轮的硬度要低于对称齿轮。为了增加塑性齿轮的硬度，在齿轮设计时，齿厚和YoungsModulus 应该被考虑进去。References 1 DENG Jiamei, CAO Jialin, WANG Zhe, etal. Finite element analyses of the bending deformation of Small module plastic gear tooth J . Mechanical Science Technology , 1997, 16 (3) : 426 430. 2 Engineering Handbook Compilation Committee. Mechanical engineering handbook M . Beijing: Mechanical Industry Press, 1982. 3 Wang J