非均质材料损伤破坏的数值模拟软件开发及强韧化机理研究

本文针对平面链网模型与空间链网模型，发展了模拟非均质材料的数值软件，旨在分析材料的损伤破坏特征，寻找材料细观结构同宏观力学行为之间的相互联系，探讨材料强韧化机理以及评估材料的力学性能。采用可视化技术设计的具有交互式功能的图象用户界面，能根据具体材料对象构造特定材料模型来分析其力学行为与服役能力。初步结果表明，无论是材料弹性阶段的性质还是损伤演化阶段材料中裂纹的萌生、扩展、汇集和材料的最终失效等现象都与已有的理论结果及试验结果符合得很好。另外，本文还对材料的强韧化机理作了探索。

层流等离子体发生器的研究

在本文的工作中，研制出了大气压层流等离子体发生器，并从试验和数值模拟两个方面对层流等离子体射流的特征和发生机理进行了分析和研究。试验观察表明，与湍流等离子体射流相比，层流等离子体射流有明显的特点，射流长而细，与周围环境气体掺混很少，能量的衰减很慢，而且几乎没有噪音。在层流等离子体发生器的研制过程中，研究了层流等离子体射流的产生机理，结果表明，工作气体流量、电源的输出特性、进气方式、电压的大小、发生器的结构和加工等对层流等离子体射流的产生有重要影响。本文还对层流和湍流等离子体射流进行了数值模拟，结果表明，工作气体的流量对层流等离子体的射流的长度有较大的影响；发生器出口的射流初始湍流度对射流的流动状态和长度也有很大的影响。数值模拟的结果和试验观察到的现象是一致的。

Microfluidic effects of transporting signaling components in cell coculture chips

A theoretical model has been developed to investigate the microfluidic transport of the signaling chemicals in the cell coculture chips. Using an epidermal growth factor (EGF)-like growth factor as the sample chemical, the effects of velocities and channel geometry were studied for the continuous-flow microchannel bioreactors. It is found that different perfusion velocities must be applied in the parallel channels to facilitate the communication, i.e., transport of the signaling component, between the coculture channels. Such communication occurs in a unidirectional way because the signaling chemicals can only flow from the high velocity area to the low velocity area. Moreover, the effect of the transport of the signaling component between the coculture channels on the growth of the monolayer cells and the multicellular tumor spheroid (MTS) in the continuous-flow coculture environment were simulated using 3D models. The numerical results demonstrated that the concentration gradients will induce the heterogeneous growth of the cells and the MTSs, which should be taken into account in designing the continuous-flow perfusion bioreactor for the cell coculture research.