Department of Mechanical Engineering, CEMMPRE, University of Coimbra, 3030-788 Coimbra, Portugal.
C-MAST, Department of Electromechanical Engineering, University of Beira Interior, Calçada Fonte do Lameiro, 6201-100 Covilhã, Portugal.
Molecules. 2021 Sep 11;26(18):5520. doi: 10.3390/molecules26185520.
Due to the enormous benefits inherent to composite materials, they have been widely used in the most diverse fields of engineering. Therefore, it is not surprising that in many of these applications they can be exposed to hostile environments, which can affect the mechanical performance of such materials. Therefore, the main goal of this work was to study the effect of immersion into different hostile solutions on the impact strength and, subsequently, to evaluate the residual fatigue life. For this purpose, the specimens were initially immersed into solutions of hydrochloric acid (HCl), sodium hydroxide (NaOH), sulphuric acid (HSO), diesel, distilled water, and seawater. Subsequently, the specimens were subjected to impact loads with an energy of 12 J and, finally, subjected to fatigue loads to assess the residual fatigue life. Seawater and NaOH solution provided the lowest impact strength. This was confirmed by the lower energy restored and impact bending stiffness (IBS), a parameter that allows evaluating the damage resistance of a composite. In terms of restored energy, for example, the seawater promoted a decrease around 30.4% in relation to the value obtained with non-immersed samples, while this value was 27.6% for the alkaline solution (NaOH). In terms of IBS, the lowest values were also obtained with these solutions (437.4 and 444.9 N/mm, respectively). Finally, the lowest residual fatigue life was also observed for these two solutions, and it was noticed that there was a direct relationship between the IBS and the residual fatigue life.
由于复合材料具有巨大的优势，它们已被广泛应用于工程学的各个领域。因此，在许多应用中，复合材料可能会暴露于恶劣环境中，这会影响到这些材料的力学性能，这并不奇怪。因此，这项工作的主要目的是研究浸入不同恶劣溶液对冲击强度的影响，然后评估残余疲劳寿命。为此，首先将试样浸入盐酸（HCl）、氢氧化钠（NaOH）、硫酸（HSO）、柴油、蒸馏水和海水中。随后，试样承受 12 J 能量的冲击载荷，最后承受疲劳载荷以评估残余疲劳寿命。海水和 NaOH 溶液提供了最低的冲击强度。这一点从恢复的能量较低和冲击弯曲刚度（IBS）得到了证实，IBS 是一个可以评估复合材料抗损伤能力的参数。例如，与未浸泡的样品相比，海水导致恢复的能量降低了约 30.4%，而碱性溶液（NaOH）则降低了 27.6%。在 IBS 方面，这两种溶液也得到了最低的值（分别为 437.4 和 444.9 N/mm）。最后，这两种溶液的残余疲劳寿命也最低，并且注意到 IBS 和残余疲劳寿命之间存在直接关系。
