Zuccarello B, Militello C, Bongiorno F
Department of Engineering, University of Palermo, Viale delle Scienze, 90128 Palermo, Italy.
Polymers (Basel). 2024 Sep 18;16(18):2630. doi: 10.3390/polym16182630.
In recent decades, in order to replace traditional synthetic polymer composites, engineering research has focused on the development of new alternatives such as green biocomposites constituted by an eco-sustainable matrix reinforced by natural fibers. Such innovative biocomposites are divided into two different typologies: random short fiber biocomposites characterized by low mechanical strength, used for non-structural applications such as covering panels, etc., and high-performance biocomposites reinforced by long fibers that can be used for semi-structural and structural applications by replacing traditional materials such as metal (carbon steel and aluminum) or synthetic composites such as fiberglass. The present research work focuses on the high-performance biocomposites reinforced by optimized sisal fibers. In detail, in order to contribute to the extension of their application under fatigue loading, a systematic experimental fatigue test campaign has been accomplished by considering four different lay-up configurations (unidirectional, cross-ply, angle-ply and quasi-isotropic) with volume fraction = 70%. The results analysis found that such laminates exhibit good fatigue performance, with fatigue ratios close to 0.5 for unidirectional and angle-ply (±7.5°) laminates. However, by passing from isotropic to unidirectional lay-up, the fatigue strength increases significantly by about four times; higher increases are revealed in terms of fatigue life. In terms of damage, it has been observed that, thanks to the high quality of the proposed laminates, in any case, the fatigue failure involves the fiber failure, although secondary debonding and delamination can occur, especially in orthotropic and cross-ply lay-up. The comparison with classical synthetic composites and other similar biocomposite has shown that in terms of fatigue ratio, the examined biocomposites exhibit performance comparable with the biocomposites reinforced by the more expensive flax and with common fiberglass. Finally, appropriate models, that can be advantageously used at the design stage, have also been proposed to predict the fatigue behavior of the laminates analyzed.
近几十年来，为了取代传统的合成聚合物复合材料，工程研究集中在开发新的替代品上，例如由天然纤维增强的生态可持续基体构成的绿色生物复合材料。这种创新的生物复合材料分为两种不同类型：随机短纤维生物复合材料，其机械强度较低，用于非结构应用，如覆盖板等；高性能生物复合材料，由长纤维增强，可通过替代传统材料（如金属（碳钢和铝））或合成复合材料（如玻璃纤维）用于半结构和结构应用。目前的研究工作集中在由优化剑麻纤维增强的高性能生物复合材料上。具体而言，为了有助于扩展其在疲劳载荷下的应用，通过考虑四种不同的铺层配置（单向、正交铺层、斜交铺层和准各向同性），体积分数 = 70%，完成了系统的实验疲劳试验。结果分析发现，这种层压板表现出良好的疲劳性能，单向和斜交铺层（±7.5°）层压板的疲劳比接近0.5。然而，从各向同性铺层转变为单向铺层时，疲劳强度显著提高约四倍；在疲劳寿命方面有更高的提高。在损伤方面，已经观察到，由于所提出的层压板质量高，在任何情况下，疲劳失效都涉及纤维失效，尽管可能会发生二次脱粘和分层，特别是在正交各向异性和正交铺层中。与经典合成复合材料和其他类似生物复合材料的比较表明，在所研究的生物复合材料的疲劳比方面，其性能与由更昂贵的亚麻增强的生物复合材料以及普通玻璃纤维相当。最后，还提出了可在设计阶段有利使用的适当模型，以预测所分析层压板的疲劳行为。
