针对用有限元法进行连续体结构拓扑优化时需不断重构网格来处理网格畸变和网格移动,且存在数值计算不稳定等问题,基于无网格径向点插值方法(Radial Point Interpolation Method,RPIM)对简谐激励下的连续体结构进行拓扑优化.选取节点的...针对用有限元法进行连续体结构拓扑优化时需不断重构网格来处理网格畸变和网格移动,且存在数值计算不稳定等问题,基于无网格径向点插值方法(Radial Point Interpolation Method,RPIM)对简谐激励下的连续体结构进行拓扑优化.选取节点的相对密度作为设计变量,以结构动柔度最小化为目标函数,基于带惩罚的各向同性固体微结构(Solid Isotropic Microstructure with Penalization,SIMP)模型建立简谐激励下的优化模型;采用伴随法求解得到目标函数的敏度分析公式;利用优化准则法求解优化模型.经典的二维连续体结构拓扑优化算例证明该方法的可行性和有效性.展开更多
板条状结构的设计域具有较大的长宽比,常规的拓扑优化方法无法获得清晰的、周期性的拓扑形式或求解困难。以结构的最小柔度为目标函数,单元相对密度为设计变量,构建周期性拓扑优化问题的数学模型。提出一种基于变密度理论固体各向同性...板条状结构的设计域具有较大的长宽比,常规的拓扑优化方法无法获得清晰的、周期性的拓扑形式或求解困难。以结构的最小柔度为目标函数,单元相对密度为设计变量,构建周期性拓扑优化问题的数学模型。提出一种基于变密度理论固体各向同性微结构材料惩罚模型法(Solid isotropic microstructures with penalization,SIMP)的周期性拓扑优化的方法。在数学模型中设置额外的约束条件,保证优化结构可以得到周期性的拓扑形式。通过优化准则法推导出虚拟子域设计变量的迭代公式,利用体积约束计算出拉格朗日乘子。引入过滤函数解决拓扑优化容易出现数值计算不稳定,导致棋盘格、网格依赖性等问题。利用所提出的方法,通过平面矩形悬臂梁结构算例,获得平面矩形悬臂梁结构的周期性拓扑形式。结果表明,在优化过程中,出现周期性的孔洞。随着迭代次数的增加,孔洞数目没有增加,说明该方法具有较强的稳健性。子域数目取值不同时,均可以得到具有周期性的拓扑形式,且具有良好的一致性。展开更多
To analyze the feasibility of utilization of thermal technology in fly ash treatment, thermal properties and microstructures of municipal solid waste incineration （MSW1） fly ash were studied by measuring the chemica...To analyze the feasibility of utilization of thermal technology in fly ash treatment, thermal properties and microstructures of municipal solid waste incineration （MSW1） fly ash were studied by measuring the chemical element composition, specific surface area, pore sizes, functional groups, TEM image, mineralogy and DSC-TG curves of raw and sintered fly ash specimens. The results show that MSWI fly ash particles mostly have irregular shapes and non-typical pore structure, and the supersonic treatment improves the pore structure; MSWI fly ash consists of Such crystals as SiO2, CaSO4 and silica-aluminates, and some soluble salts like KCl and NaCl. During the sintering process, mineralogy changes largely and novel solid solutions are produced gradually with the rise of temperature. Therefore, the utilization of a proper thermal technology not only destructs those persistent organic toxicants but also stabilizes hazardous heavy metals in MSWI fly ash.展开更多
A new Mg-14Al-0.5Mn alloy that exhibits a wide solidification range and sufficient fluidity for semi-solid forming was designed. And the rnicrostructure evolution of semi-solid Mg-14Al-0.5Mn alloy during isothermal he...A new Mg-14Al-0.5Mn alloy that exhibits a wide solidification range and sufficient fluidity for semi-solid forming was designed. And the rnicrostructure evolution of semi-solid Mg-14Al-0.5Mn alloy during isothermal heat treatment was investigated. The mechanism of the microstructure evolution and the processing conditions for isothermal heat treatment were also discussed. The results show that the microstructures of cast alloys consist of α-Mg,β-Mg17Al12 and a small amount of Al-Mn compounds. After holding at 520 ℃ for 3 min, the phases of β-Mg17Al12 and eutectic mixtures in the Mg-14Al-0.5Mn alloy melt and the microstructures of α-Mg change from developed dendrites to irregular solid particles. With increasing the isothermal time, the amount of liquid increases, and the solid particles grow large and become spherical. When the holding time lasts for 20 min or even longer, the solid and liquid phases achieve a state of dynamic equilibrium.展开更多
文摘针对用有限元法进行连续体结构拓扑优化时需不断重构网格来处理网格畸变和网格移动,且存在数值计算不稳定等问题,基于无网格径向点插值方法(Radial Point Interpolation Method,RPIM)对简谐激励下的连续体结构进行拓扑优化.选取节点的相对密度作为设计变量,以结构动柔度最小化为目标函数,基于带惩罚的各向同性固体微结构(Solid Isotropic Microstructure with Penalization,SIMP)模型建立简谐激励下的优化模型;采用伴随法求解得到目标函数的敏度分析公式;利用优化准则法求解优化模型.经典的二维连续体结构拓扑优化算例证明该方法的可行性和有效性.
文摘板条状结构的设计域具有较大的长宽比,常规的拓扑优化方法无法获得清晰的、周期性的拓扑形式或求解困难。以结构的最小柔度为目标函数,单元相对密度为设计变量,构建周期性拓扑优化问题的数学模型。提出一种基于变密度理论固体各向同性微结构材料惩罚模型法(Solid isotropic microstructures with penalization,SIMP)的周期性拓扑优化的方法。在数学模型中设置额外的约束条件,保证优化结构可以得到周期性的拓扑形式。通过优化准则法推导出虚拟子域设计变量的迭代公式,利用体积约束计算出拉格朗日乘子。引入过滤函数解决拓扑优化容易出现数值计算不稳定,导致棋盘格、网格依赖性等问题。利用所提出的方法,通过平面矩形悬臂梁结构算例,获得平面矩形悬臂梁结构的周期性拓扑形式。结果表明,在优化过程中,出现周期性的孔洞。随着迭代次数的增加,孔洞数目没有增加,说明该方法具有较强的稳健性。子域数目取值不同时,均可以得到具有周期性的拓扑形式,且具有良好的一致性。
基金Project(50808184) supported by the National Natural Science Foundation of China
文摘To analyze the feasibility of utilization of thermal technology in fly ash treatment, thermal properties and microstructures of municipal solid waste incineration （MSW1） fly ash were studied by measuring the chemical element composition, specific surface area, pore sizes, functional groups, TEM image, mineralogy and DSC-TG curves of raw and sintered fly ash specimens. The results show that MSWI fly ash particles mostly have irregular shapes and non-typical pore structure, and the supersonic treatment improves the pore structure; MSWI fly ash consists of Such crystals as SiO2, CaSO4 and silica-aluminates, and some soluble salts like KCl and NaCl. During the sintering process, mineralogy changes largely and novel solid solutions are produced gradually with the rise of temperature. Therefore, the utilization of a proper thermal technology not only destructs those persistent organic toxicants but also stabilizes hazardous heavy metals in MSWI fly ash.
基金Projects(2006BA104B04-1,2006BAE04B07-3)supported by the National Science and Technology Supporting Program of ChinaProject(2007KZ05)supported by the Science and Technology Supporting Project of Changchun City,China+1 种基金Project(2008)supported by the Open Subject of State Key Laboratory of Rare Earth Resource Utilization,ChinaProject supported by the"985 Project"of Jilin University,China
文摘A new Mg-14Al-0.5Mn alloy that exhibits a wide solidification range and sufficient fluidity for semi-solid forming was designed. And the rnicrostructure evolution of semi-solid Mg-14Al-0.5Mn alloy during isothermal heat treatment was investigated. The mechanism of the microstructure evolution and the processing conditions for isothermal heat treatment were also discussed. The results show that the microstructures of cast alloys consist of α-Mg,β-Mg17Al12 and a small amount of Al-Mn compounds. After holding at 520 ℃ for 3 min, the phases of β-Mg17Al12 and eutectic mixtures in the Mg-14Al-0.5Mn alloy melt and the microstructures of α-Mg change from developed dendrites to irregular solid particles. With increasing the isothermal time, the amount of liquid increases, and the solid particles grow large and become spherical. When the holding time lasts for 20 min or even longer, the solid and liquid phases achieve a state of dynamic equilibrium.
