Recent Advances on Smart Lightweight Carbon Fiber/Aluminum Hybrid Composite Structures

Due to the growing demand for lightweight materials in different industries, the selection and hybridization of engineering fibers and metals is becoming a promising solution as it combines the outstanding mechanical, thermal, and weathering-resistance properties from both materials. Due to their lightweight and strong mechanical properties, carbon fiber/aluminum hybrid composite-based structures have become the most dominant materials used by engineers and researchers in the recent two decades. In the present chapter, the recent development on the processing techniques and mechanical performances of these hybrid structures are reviewed in detail. In addition, the applications of these kinds of structural materials in the various industrial sectors including, automobile, aerospace, design of industrial robots, and fire protection are summarized.

Artificial Weathering Resistance Test Methods for Building Performance Assessment of Profiles Made of Natural Fibre-Reinforced Polymer Composites

A growing popularity of profiles made of natural fibre-reinforced polymer composites in civil engineering encourages determining test methods relevant for building performance assessment. Weathering resistance is among the key aspects that condition the durability of building structures. The paper includes a comparative analysis of two artificial weathering resistance test methods. Polyvinyl chloride and wood flour composite profiles were tested. They were subjected to UV and spraying (X-exposure) and UV, spraying and wetting by condensation (F-exposure), both at different exposure times. The influence of the applied weathering procedures on the composite’s microstructure and its mechanical characteristics were analysed. No changes in the microstructure of brittle fractures were observed. However, surface morphology changes were revealed, noticeably greater following X-exposure than F-exposure. F-exposure exerted significant influence on the mechanical properties of brushed profile, including, but not limited to, flexural modulus. Whereas X-exposure exerted more influence on the mechanical properties of non-brushed profile.

Petrophysical Properties of Limestones - Influence On Behaviour Under Different Environmental Conditions And Applications

Limestones have wide variety, namely by differences in the process of formation, mineralogical composition, grain size and texture. Such variability leads to differences in weathering characteristics and behaviour under different environmental conditions and applications. Therefore, detailed studies are mandatory to assess the main factors controlling the physical-mechanical properties and the durability to propose the best applications for the limestones. This study presents the petrographic and petrophysical data of eleven selected Portuguese limestones. Texture, mineralogy and porosity were identified as key parameters for the durability of limestones. Two main groups were identified regarding the texture/petrography and weathering resistance; the compact micritic limestones and with the sparitic grainstones. For the first time an outstanding bowing behaviour was identified in a limestone, probably related with clay swelling minerals and iron oxides present in the micrite groundmass around or in the stylolitic planes.

Novel Engineered Materials: Epoxy Resin Nanocomposite Reinforced with Modified Epoxidized Natural Rubber and Fibers for Low-Speed Wind Turbine Blades

The objective of this study was to investigate nanocomposite materials with good outdoor resistance for wind turbine blade application. The nanocomposites based on epoxy resin with 5% of epoxidized natural rubber (ENR 50), 3% of nanofiller, and glass fibers, were subjected to experiments. The weathering resistance of nanocomposites was evaluated from the change in mechanical properties caused by accelerated aging, induced by UVB radiation in a weathering chamber. The accelerated aging improved tensile strength by about 35% at 168 h of exposure to UVB, via a curing effect. The nanocomposites were optimized for all the parts of wind turbine blades (Savonius and Darrieus types) that are generally designed for high strength, low weight, weathering resistance, and low rotational speed (2 m/s). A tree wind turbine with nanocomposite blades produced 5 kW power output when tested. Based on the findings in this work, the innovative nanocomposites have potential in manufacturing wind turbines to generate electricity.

Enhancing Weathering Resistance of Wood—A Review

Wood is a truly sustainable and aesthetically pleasant material used in indoor and outdoor applications. Every material, including wood, is expected to have long-term durability and to retain its original appearance over time. One of the major disadvantages of wood is the deterioration of its surface when exposed outdoors, known as weathering. Although weathering is primarily a surface phenomenon, it is an important issue for wood products as it affects their appearance, service life, and wood-coating performance. To encourage the use of wood as a material for joinery and other building components, the results of research into increasing the weathering resistance of wood are extremely significant. The development of weathering protection methods is of great importance to reduce the maintenance requirements for wood exposed outdoors and can have a major environmental impact. There are various methods of protecting wood surfaces against weathering. This paper provides a literature survey on the recent research results in protecting wood from weathering. The topics covered include surface treatments of wood with photostabilizers; protection with coatings; the deposition of thin film onto wood surfaces; treatments of wood with inorganic metal compounds and bio-based water repellents; the chemical modification of wood; the modification of wood and wood surfaces with thermosetting resins, furfuryl alcohol, and DMDHEU; and the thermal modification of wood.