含裂纹锆合金包壳管氢致多场耦合行为的数值模拟研究

考虑氢化物应力再取向，给出了锆合金包壳管氢致多场耦合行为的理论模型。建立了相应的多场耦合计算方法，编程获得了有限元程序。针对内压作用下的含轴向裂纹包壳管，建立了有限元模型，对其氢致多场耦合行为进行了计算分析。研究结果表明：对于含大量固溶氢原子的含裂纹包壳管，只有裂纹尖端区域析出较多的氢化物，这主要是由于此处存在很大的静水应力梯度和氢原子浓度梯度，并具有较低的氢原子固溶度；裂纹尖端析出的氢化物绝大部分沿包壳管径向，致使包壳管易于产生径向开裂，威胁其安全性；内压施加完成后，因氢化物析出膨胀，裂纹尖端区域的环向应力、径向应力、静水应力及其梯度均随时间而降低，导致氢化物析出逐渐减速。

Numerical Simulation on Hydrogen-diffusion-induced Multi-field Coupling Behavior in Zircaloy Cladding Tube with Crack

With the stress-reorientation of hydrides considered, the theoretical models were given for the hydrogen-diffusion-induced multi-field coupling behaviors in zircaloy cladding tubes. The corresponding multi-field coupling computational methods were developed and the finite element procedures were obtained. For an axially-cracked cladding tube subjected to internal pressures, the finite element model was established to calculate and analyze the hydrogen-diffusion-induced multi-field coupling behaviors. The research results indicate that for a cracked cladding tube initially containing plenty of hydrogen atoms in solid solution, only considerable amount of hydrides precipitate around the crack tip, which mainly results from the high hydrostatic stress gradients and concentration gradients of hydrogen in solid solution there, together with lower terminal solid solubility; The majority of hydrides at the crack tip precipitate along the radial orientation, which will induce occurrence of radial cracking of cladding tubes to threaten their safety; After applying the internal pressures, due to the expansion strains induced by hydride precipitation, the hoop stress, the radial stress, the hydrostatic stress and its gradient will decrease with time, which results in a lower velocity of hydride precipitation.