共查询到15条相似文献,搜索用时 203 毫秒
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基于微观组织优化的锻造工艺预成形及毛坯形状优化设计 总被引:3,自引:0,他引:3
以锻件晶粒尺寸细小均匀为目标,以预成形形状设计为对象,提出了锻造成形过程微观组织优化设计方法,构建了晶粒尺寸、锻件形状子目标函数以及无量纲化的总目标函数,确定了预成形形状作为优化过程的设计变量;给出了优化设计的具体步骤,采用微观遗传算法和有限元模拟方法开发了基于预成形设计的锻造过程微观组织优化程序;并对典型的圆柱体镦粗进行了面向微观组织优化的预成形设计,给出了能够获得具有良好微观组织的镦粗成形预成形模具型腔形状。通过分析不同高径比的初始毛坯形状对微观组织优化目标函数值的影响,给出了较为合理的初始毛坯形状高径比取值范围。 相似文献
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锻造成形微观组织优化建模及应用 总被引:8,自引:0,他引:8
以锻件晶粒度分布的均匀性与细小化为目标,建立了锻造变形过程的微观组织演变模型,并给出了优化目标函数表达式。采用刚塑性有限元和遗传优化算法相结合,开发了微观组织模拟与优化软件,并对典型的圆柱体镦粗工艺过程进行了微观组织模拟与优化。优化结果表明,影响变形均匀性的摩擦因素显著影响成形后的微观组织晶粒度的分布均匀性和细小化,同时对其它工艺因素的优化也能一定程度地实现对最终锻件组织均匀和细小化的控制。研究结果表明,在有限元数值模拟基础上建立微观遗传优化算法,能够对锻造等金属体积成形过程中的工艺参数与材料状态参数等实施优化,以达到通过控制成形工艺因素来优化微观组织,而实现提高产品性能的目的。 相似文献
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材料塑性成形过程最优化设计—Ⅰ有限元灵敏度分析方法 总被引:16,自引:2,他引:14
本文采用有限元方法建立了一种非稳态材料塑性成形过程的灵敏度分析理论和模具形状优化设计方法。采用三次B样条函数描述预成形模具形状,B样条函数的控制点坐标(系数)作为优化设计变量,通过对控制点坐标的优化设计,使实际终成形件形状与理想终成形件形状之间的差别最小,从而实现预成形模具形状的优化设计,详细建立了目标函数、有限元节点坐标、节点速度对优化设计变量的解析灵敏度方程及其彼此之间的数学关系,并给出了节点速度灵敏度的边界条件 相似文献
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多目标优化在锻造毛坯形状优化设计中的应用 总被引:2,自引:0,他引:2
以形状相对简单的单工序锻件为研究对象,以同时获得材料消耗最小和变形程度最均匀的终锻件为优化目标,对锻造过程毛坯形状进行多目标优化设计的研究。给出了单工序锻件形状优化设计的总的目标函数及其各子目标函数的表示方法及计算表达式,以毛坯的高径(宽)比作为优化设计的变量,基于刚粘塑性有限元理论,采用黄金分割法进行优化迭代,编制了相应的程序,并对一典型的轴对称H型锻件的毛坯形状进行了多目标的优化设计,取得了明显的效果。 相似文献
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基于响应面法(RSM)的锻造预成形多目标优化设计 总被引:3,自引:1,他引:3
以航空发动机涡轮盘锻件为研究对象,应用响应面法(Response surfce Methodology,RSM)和有限元数值模拟(FEM)对锻造过程预成形设计的多目标优化问题进行了研究.首先以模具充填完整和提高锻件内变形均匀性为目标,建立了有限元数值模拟与响应面法相结合的二阶分析模型,并对优化结果进行了讨论.其次,在原优化设计的基础上以降低锻造过程的成形载荷为目标进行了预成形再设计.结果表明,应用响应面法可灵活有效的对难变形材料锻造预成形坯料形状进行多目标优化设计. 相似文献
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G. Q. Zhao R. Hufi A. Hutter R. V. Grandhi 《Journal of Materials Engineering and Performance》1997,6(3):303-310
This paper uses a finite element-based sensitivity analysis method to design the preform die shape for metal forming processes.
The sensitivity analysis was developed using the rigid visco-plastic finite element method. The preform die shapes are represented
by cubic B-spline curves. The control points or coefficients of the B-spline are used as the design variables. The optimization
problem is to minimize the difference between the realized and the desired final forging shapes. The sensitivity analysis
includes the sensitivities of the objective function, nodal coordinates, and nodal velocities with respect to the design variables.
The remeshing procedure and the interpolation/transfer of the history/dependent parameters are considered. An adjustment of
the volume loss resulting from the finite element analysis is used to make the workpiece volume consistent in each optimization
iteration and improve the optimization convergence. In addition, a technique for dealing with fold-over defects during the
forming simulation is employed in order to continue the optimization procedures of the preform die shape design. The method
developed in this paper is used to design the preform die shape for both plane strain and axisymmetric deformations with shaped
cavities. The analysis shows that satisfactory final forging shapes are obtained using the optimized preform die shapes. 相似文献
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Guoqun Zhao Ed Wright Ramana V. Grandhi 《International Journal of Machine Tools and Manufacture》1997,37(9):1251-1271
A sensitivity analysis method for preform die shape design in net-shape forging processes is developed in this paper using the rigid viscoplastic finite element method. The preform die shapes are represented by cubic B-spline curves. The control points or coefficients of B-spline are used as the design variables. The optimization problem is to minimize the zone where the realized and desired final forging shapes do not coincide. The sensitivities of the objective function, nodal coordinates and nodal velocities with respect to the design variables are developed in detail. A procedure for computing the sensitivities of history-dependent functions is presented. The remeshing procedure and the interpolation/transfer of the history-dependent parameters, such as effective strain, are stated. The procedures of sensitivity analysis based preform die design are also described. In addition, a method for the adjustment of the volume loss resulting from the finite element analysis is given in order to make the workpiece volume consistent in each optimization iteration. The method developed in this paper is used to design the preform die shape of H-shaped forging processes, including plane strain and axisymmetric deformations. The results show that a flashless forging with a complete die fill is realized using the optimized preform die shape. 相似文献
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复杂汽车结构件多工位级进模具有工位多、结构复杂、工位关联性强的特点,其冲裁工位刃口线受成形工位的影响,刃口线的预测精度低。基于此,提出一种基于应变路径的精确刃口线优化方法。采用有限元逆算法对零件分步展开,获得板料的初始轮廓线;基于真实压力机参数、精细化模面和真实工艺参数,对条料进行全工序精细化数值模拟。将板料初始网格的边界节点基于B样曲线拟合,提取成形前后边界节点的应变及其路径。以设计零件的产品边界为目标,建立精确刃口线优化的目标函数,通过调整B样条曲线,对轮廓线进行迭代优化。实例表明,该优化方法可有效提高复杂多工位级进模刃口线优化的精度和效率。 相似文献
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Microstructure optimization in design of forging processes 总被引:3,自引:0,他引:3
Zhenyan Gao Ramana V. Grandhi 《International Journal of Machine Tools and Manufacture》2000,40(5):691-711
A new approach based on sensitivity analysis for optimizing the microstructure development during the forging processes is proposed in this work. The analytical sensitivities of the recrystallization volume fraction and dynamically recrystalized grain size with respect to the design variables are derived. The mean grain size in each finite element is introduced so that the complex recrystallization mechanics, such as no recrystallization, partial recrystallization and complete recrystallization are all considered. The objective is to minimize a function describing the variance of mean grain size and the average value of mean grain size in the whole final product. Two constraints are imposed on die underfill and excessive material waste. Two different kinds of design variables are considered, including state parameter (initial shape of billet) and process parameter (die velocity). The optimization scheme is demonstrated with the design of a turbine disk made of Waspaloy in non-isothermal forging process. The optimal initial shape of billet and the die velocity are obtained. 相似文献