Kumar Rajnish, Madsen Bo, Lilholt Hans, Mikkelsen Lars P
Division of Wind Energy Materials and Components, Department of Wind and Energy Systems, Technical University of Denmark, 4000 Roskilde, Denmark.
Materials (Basel). 2022 May 31;15(11):3911. doi: 10.3390/ma15113911.
This paper presents an analytical model that quantifies the stress ratio between two test specimens for the same probability of failure based on the Weibull weakest link theory. The model takes into account the test specimen geometry, i.e., its shape and volume, and the related non-constant stress state along the specimen. The proposed model is a valuable tool for quantifying the effect of a change of specimen geometry on the probability of failure. This is essential to distinguish size scaling from the actual improvement in measured strength when specimen geometry is optimized, aiming for failure in the gauge section. For unidirectional carbon fibre composites with Weibull modulus m in the range 10-40, it can be calculated by the model that strength measured with a straight-sided specimen will be 1-2% lower than the strength measured with a specific waisted butterfly-shaped specimen solely due to the difference in test specimen shape and volume.
本文提出了一个基于威布尔最弱链理论的分析模型，该模型可对具有相同失效概率的两个测试样本之间的应力比进行量化。该模型考虑了测试样本的几何形状，即其形状和体积，以及沿样本的相关非恒定应力状态。所提出的模型是量化样本几何形状变化对失效概率影响的一个有价值的工具。当优化样本几何形状以使其在标距段失效时，这对于区分尺寸缩放与实测强度的实际提高至关重要。对于威布尔模量m在10至40范围内的单向碳纤维复合材料，通过该模型可以计算出，仅由于测试样本形状和体积的差异，直边样本测得的强度将比特定腰形蝶形样本测得的强度低1%至2%。
