转轴动力学特性对离心泵压力脉动的影响分析

对于电动泵的研究而言,离心泵、转轴和电机应视为一个完整的系统来分析。若忽略了设备间的相互影响,单独对系统中的某一设备进行分析计算将可能无法通过仿真模型计算得到实验过程中出现的所有频率成分。本文建立了包括电机、转轴和泵在内的多场耦合仿真模型,用于分析轴在扭转方向的动力学特性对泵运行状态的影响。首先,建立了电机与水泵的仿真模型,并用转轴将其联系起来,实现系统的耦合仿真模拟;然后,计算了电机、转轴和水泵在相互作用影响下的转速波动情况和泵出口的压力脉动情况。结果表明,系统中不同设备间的转矩和转速是相互联系的;转轴同时连接着电机与水泵,其扭振特性也会在水泵瞬时转速的频率成分中体现;水泵运行转速的波动会进一步影响其壁面压力脉动的特性,最终可能导致在泵壳的振动信号中出现与水泵自身无关的频率成分。

High Impact Resistance Epoxy Resins by Incorporation of Quadruply Hydrogen Bonded Supramolecular Polymers

A bisphenol A based epoxy was incorporated with a quadruply hydrogen bonded supramolecular polymer as a toughening agent to prepare a composite epoxy resin with higher impact resistance. The supramolecular polymer comprising poly-（propylene glycol） bis（2-aminopropyl） ether chains and 2-ureido-4[1H]-pyrimidinone moieties（UPy） self-assembled into spherical domains with sizes of 300 nm to 600 nm in diameter by micro phase separation in bulk epoxy matrixes. A significant improvement of 300% in impact resistance of the supramolecular polymer incorporated epoxy resin was obtained when the content of supramolecular polymer was 10 wt%. Tensile tests showed that the mechanical properties of the modified epoxy resin containing the hydrogen-bonded supramolecular polymers are also improved compared with those of the neat epoxy resin.