Electro-Thermo-Elastic Simulation of Graphite Tools Used in SPS Processes
Electro-Thermo-Elastic Simulation of Graphite Tools Used in SPS Processes
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SPS 工艺中使用的石墨工具的电热弹性模拟
DOI：
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发表时间：
2013
期刊：
影响因子：
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通讯作者：
N. Frage
中科院分区：
文献类型：
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作者：
S. Hartmann;S. Rothe;N. Frage
在现场辅助烧结技术或放电等离子烧结技术范围内，试验机中的所有材料都会经历非常大的温度变化。将需要烧结的粉末材料填充到石墨模具中并通过石墨冲头机械加载。热量通过电感应产生，冷却过程通过传导和辐射进行。加热和冷却过程都非常快。为了了解高负载石墨零件的加工过程，必须进行实验、建模和计算。在热方面，必须对热容和热导率等与温度相关的材料属性进行建模。由于热容量并不独立于亥姆霍兹自由能，因此需要特别考虑自由能。另一方面，必须考虑电阻率的温度变化和石墨工具的材料性能。因此，“欧姆定律”的材料特性也必须建模。由电、热和机械场组成的全耦合系统通过整体有限元方法进行数值求解。使用有限元进行空间离散后，得到一个微分代数方程组，该方程组通过对角隐式龙格-库塔方法求解。解决了数值中的问题和悬而未决的问题，并讨论了对实际应用程序进行建模的问题。
In the range of field-assisted sintering technology or spark plasma sintering all materials in the testing machine undergo very large temperature changes. The powder material, which has to be sintered, is filled into a graphite die and mechanically loaded by a graphite punch. The heat is produced by electrical induction and the cooling process is performed by conduction and radiation. Both the heating and the cooling process are very fast. In order to understand the process of the highly loaded graphite parts, experiments, modeling and computations have to be carried out. On the thermal side the temperature-dependent material properties such as heat capacity and heat conductivity have to be modeled. Since the heat capacity is not independent of the Helmholtz free-energy a particular consideration of the free-energy is carried out. On the other hand, the temperature changes of the electrical resistivity and the material properties of the graphite tool must be taken into considerations. Accordingly, the material properties of “Ohm’s law” must be modeled as well. The fully coupled system comprising the electrical, thermal and mechanical field are solved numerically by a monolithic finite element approach. After the spatial discretization using finite elements one arrives at a system of differential-algebraic equations which is solved by means of diagonally implicit Runge-Kutta methods. Issues and open questions in the numerics are addressed and problems in modeling a real application are discussed.