Zuccarello Bernardo, Bongiorno Francesco, Militello Carmelo
Department of Engineering, University of Palermo, Viale Delle Scienze, 90128 Palermo, Italy.
Polymers (Basel). 2024 Nov 28;16(23):3341. doi: 10.3390/polym16233341.
Within the range of composite laminates for structural applications, sandwich laminates are a special category intended for applications characterized by high flexural stresses. As it is well known from the technical literature, structural sandwich laminates have a simple configuration consisting of two skins of very strong material, to which the flexural strength is delegated, between which an inner layer (core) of light material with sufficient shear strength is interposed. As an example, a sandwich configuration widely used in civil, naval, and mechanical engineering is that obtained with fiberglass skins and a core of various materials, such as polyurethane foam or another lightweight material, depending on the application. Increasingly stringent regulations aimed at protecting the environment by reducing harmful emissions of carbon dioxide and carbon monoxide have directed recent research towards the development of new composites and new sandwiches characterized by low environmental impact. Among the various green composite solutions proposed in the literature, a very promising category is that of high-performance biocomposites, which use bio-based matrices reinforced by fiber reinforcements. This approach can also be used to develop green sandwiches for structural applications, consisting of biocomposite skins and cores made by low-environmental impact or renewable materials. In order to make a contribution to this field, a structural sandwich consisting of high-performance sisal-epoxy biocomposite skins and an innovative renewable core made of balsa wood laminates with appropriate lay-ups has been developed and then properly characterized in this work. Through a systematic theoretical-experimental analysis of three distinct core configurations, the unidirectional natural core, the cross-ply type, and the angle-ply type, it has been shown how the use of natural balsa gives rise to inefficient sandwiches, whereas performance optimization is fully achieved by considering the angle-ply core type [±45/90]. Finally, the subsequent comparison with literature data of similar sandwiches has shown how the optimal configuration proposed can be advantageously used to replace synthetic glass-resin sandwiches widely used in various industrial sectors (mechanical engineering, shipbuilding, etc.) and in civil engineering.
在用于结构应用的复合材料层压板范围内，夹层层压板是一类特殊的层压板，适用于以高弯曲应力为特征的应用。从技术文献中可知，结构夹层层压板具有简单的结构，由两层非常坚固的材料蒙皮组成，弯曲强度由这两层蒙皮承担，两层蒙皮之间夹有一层具有足够剪切强度的轻质材料内层（芯层）。例如，在土木、船舶和机械工程中广泛使用的一种夹层结构是由玻璃纤维蒙皮和各种材料的芯层组成，芯层材料可以是聚氨酯泡沫或其他轻质材料，具体取决于应用。旨在通过减少二氧化碳和一氧化碳有害排放来保护环境的法规日益严格，这促使近期的研究朝着开发具有低环境影响的新型复合材料和新型夹层材料方向发展。在文献中提出的各种绿色复合材料解决方案中，一个非常有前景的类别是高性能生物复合材料，它使用由纤维增强材料增强的生物基基体。这种方法也可用于开发用于结构应用的绿色夹层材料，其由生物复合材料蒙皮和由低环境影响或可再生材料制成的芯层组成。为了在这一领域做出贡献，本文开发了一种结构夹层材料，它由高性能剑麻 - 环氧树脂生物复合材料蒙皮和由具有适当铺层的轻木层压板制成的创新可再生芯层组成，并对其进行了适当的表征。通过对三种不同芯层配置（单向天然芯层、正交铺层类型和斜交铺层类型）进行系统的理论 - 实验分析，结果表明使用天然轻木会导致夹层材料效率低下，而通过考虑斜交铺层芯层类型[±45/90]可完全实现性能优化。最后，与类似夹层材料的文献数据进行后续比较表明，所提出的最佳配置可有利地用于替代在各个工业领域（机械工程、造船等）和土木工程中广泛使用的合成玻璃 - 树脂夹层材料。
