A new seismic ray-tracing method is put forward based on parabolic travel-time interpolation(PTI) method, which is more accurate than the linear travel-time interpolation (LTI) method. Both PTI method and LTI method a...A new seismic ray-tracing method is put forward based on parabolic travel-time interpolation(PTI) method, which is more accurate than the linear travel-time interpolation (LTI) method. Both PTI method and LTI method are used to compute seismic travel-time and ray-path in a 2-D grid cell model. Firstly, some basic concepts are introduced. The calculations of travel-time and ray-path are carried out only at cell boundaries. So, the ray-path is always straight in the same cells with uniform velocity. Two steps are applied in PTI and LTI method, step 1 computes travel-time and step 2 traces ray-path. Then, the derivation of LTI formulas is described. Because of the presence of refraction wave in shot cell, the formula aiming at shot cell is also derived. Finally, PTI method is presented. The calculation of PTI method is more complex than that of LTI method, but the error is limited. The results of numerical model show that PTI method can trace ray-path more accurately and efficiently than LTI method does.展开更多
树脂传递模塑成型(resin transfer molding, RTM)工艺是树脂基复合材料制造中主要的一种成型工艺,对该工艺的模拟仿真可在RTM制件的工艺设计优化方面起到关键作用。本工作以实际RTM工艺生产需求为基础,在二维等温RTM工艺仿真程序基础上...树脂传递模塑成型(resin transfer molding, RTM)工艺是树脂基复合材料制造中主要的一种成型工艺,对该工艺的模拟仿真可在RTM制件的工艺设计优化方面起到关键作用。本工作以实际RTM工艺生产需求为基础,在二维等温RTM工艺仿真程序基础上,突破热流耦合计算等关键技术,采用控制体有限元(CV/FEM)方法,研发三维非等温RTM成型仿真模型。该仿真模型基于Darcy方程、连续性方程、能量守恒方程、固化反应方程以及多个流变固化模型,采用半离散方法和三收敛标准,可有效解决非等温RTM仿真过程的模具预热、树脂非等温充填过程的黏度变化、固化放热等仿真问题,经过平板实验件及机匣件应用验证,可有效预测RTM充填时间、速度及压力等关键结果,结果精度与国际同类产品相当,在核心仿真能力上达到了国外商业仿真模型的同等水平,基本具备了针对实际复杂结构零件开展仿真的能力。展开更多
文摘A new seismic ray-tracing method is put forward based on parabolic travel-time interpolation(PTI) method, which is more accurate than the linear travel-time interpolation (LTI) method. Both PTI method and LTI method are used to compute seismic travel-time and ray-path in a 2-D grid cell model. Firstly, some basic concepts are introduced. The calculations of travel-time and ray-path are carried out only at cell boundaries. So, the ray-path is always straight in the same cells with uniform velocity. Two steps are applied in PTI and LTI method, step 1 computes travel-time and step 2 traces ray-path. Then, the derivation of LTI formulas is described. Because of the presence of refraction wave in shot cell, the formula aiming at shot cell is also derived. Finally, PTI method is presented. The calculation of PTI method is more complex than that of LTI method, but the error is limited. The results of numerical model show that PTI method can trace ray-path more accurately and efficiently than LTI method does.
文摘树脂传递模塑成型(resin transfer molding, RTM)工艺是树脂基复合材料制造中主要的一种成型工艺,对该工艺的模拟仿真可在RTM制件的工艺设计优化方面起到关键作用。本工作以实际RTM工艺生产需求为基础,在二维等温RTM工艺仿真程序基础上,突破热流耦合计算等关键技术,采用控制体有限元(CV/FEM)方法,研发三维非等温RTM成型仿真模型。该仿真模型基于Darcy方程、连续性方程、能量守恒方程、固化反应方程以及多个流变固化模型,采用半离散方法和三收敛标准,可有效解决非等温RTM仿真过程的模具预热、树脂非等温充填过程的黏度变化、固化放热等仿真问题,经过平板实验件及机匣件应用验证,可有效预测RTM充填时间、速度及压力等关键结果,结果精度与国际同类产品相当,在核心仿真能力上达到了国外商业仿真模型的同等水平,基本具备了针对实际复杂结构零件开展仿真的能力。
