In Sweden, spent nuclear fuel is planned to be disposed off by placing it in canisters which are made of oxygen free copper alloyed with 50 ppm phosphorus. The canisters are expected to stay intact for thousands of years. During the long term disposal, the canisters will be exposed to mechanical pressure from the surroundings at temperatures up to 100 °C and this will result in creep. To investigate the role of the complex stress conditions on the canisters, creep tests under multiaxial stress state are needed. In the present work, creep tests under multiaxial stress state with three different notch profiles (acuity 0.5, 2, and 5, respectively) at 75 °C with net section stresses ranging from 170 MPa to 245 MPa have been performed.

To interpret the experimental results, finite element computations have been conducted. With the help of the reference stress, the rupture lifetime in the multiaxial tests was estimated. The prediction was more precise for the higher acuities than for the lower one. In order to predict the creep deformation of the canisters for the long service period, fundamental creep models are considered. Previously developed basic models are used to compute the creep deformation in the multiaxial tests. Although the scatter is large, the agreement with the experiments is considered as acceptable, indicating that the basic models which have been successfully developed for uniaxial creep tests can also be used to describe multiaxial creep tests. Notch strengthening was observed for copper.

在瑞典，计划将乏核燃料放到由碳含量为50 ppm的无氧铜制成的碳罐中进行处理。预计这些罐将完好无损地保存数千年。在长期处置过程中，碳罐将承受高达100°C的高温环境下的机械压力，这将导致蠕变。为了研究罐上复杂应力条件的作用，需要在多轴应力状态下进行蠕变测试。在目前的工作中，已经在多轴应力状态下在75°C下以三种不同的缺口轮廓（分别为0.5、2和5的锐度）进行了蠕变测试，净截面应力范围为170 MPa至245 MPa。

为了解释实验结果，进行了有限元计算。借助于参考应力，估算了多轴试验中的断裂寿命。对于较高的敏锐度的预测比对于较低敏锐度的预测更为精确。为了预测罐在长期使用期间的蠕变变形，考虑了基本蠕变模型。先前开发的基本模型用于在多轴测试中计算蠕变变形。尽管散点很大，但与实验的一致性被认为是可以接受的，这表明已成功开发出用于单轴蠕变试验的基本模型也可以用于描述多轴蠕变试验。观察到铜的缺口增强。