Song Yichi, Magmanlac Doneill J, Tagarielli Vito L
Department of Aeronautical Engineering, Imperial College London, London, SW7 2AZ, UK.
Sci Rep. 2022 Jan 10;12(1):472. doi: 10.1038/s41598-021-04452-9.
We propose and assess a procedure to measure the damage evolution in solids as a function of the applied strain, by conducting stiffness-sensing mechanical tests. These tests consist in superimposing to a monotonically increasing applied strain numerous, low-amplitude unloading/reloading cycles, and extracting the current stiffness of the specimens from the slope of the stress-strain curve in each of the unloading/reloading cycles. The technique is applied to a set of polymeric and metallic solids with a wide range of stiffness, including CFRP laminates loaded through the thickness, epoxy resins, injection-moulded and 3D printed PLA and sintered Ti powders. The tests reveal that, for all the materials tested, damage starts developing at the very early stages of deformation, during what is commonly considered an elastic response. We show that the test method is effective and allows enriching the data extracted from conventional mechanical tests, for potential use in data-driven constitutive models. We also show that the measurements are consistent with the results of acoustic and resistive measurements, and that the method can be used to quantify the viscous response of the materials tested.
我们提出并评估了一种通过进行刚度传感力学试验来测量固体材料损伤演化与所施加应变关系的方法。这些试验包括在单调增加的外加应变上叠加大量低振幅的卸载/再加载循环，并从每个卸载/再加载循环的应力-应变曲线斜率中提取试样的当前刚度。该技术应用于一系列具有广泛刚度的聚合物和金属固体材料，包括沿厚度方向加载的碳纤维增强塑料（CFRP）层压板、环氧树脂、注塑成型和3D打印的聚乳酸（PLA）以及烧结钛粉。试验表明，对于所有测试材料，损伤在变形的非常早期阶段就开始发展，即在通常认为的弹性响应阶段。我们表明该测试方法是有效的，并且能够丰富从传统力学试验中提取的数据，可用于数据驱动的本构模型。我们还表明，测量结果与声学和电阻测量结果一致，并且该方法可用于量化所测试材料的粘性响应。
