Sensing Technology (ST) plays a key role in Structural Health-Monitoring (SHM) systems. ST focuses on developing sensors, sensory systems, or smart materials that monitor a wide variety of materials’ properties aiming to create smart structures and smart materials, using Embedded Sensors (ESs), and enabling continuous and permanent measurements of their structural integrity. The integration of ESs is limited to the processing technology used to embed the sensor due to its high-temperature sensitivity and the possibility of damage during its insertion into the structure. In addition, the technological process selection is dependent on the base material’s composition, which comprises either metallic or composite parts. The selection of smart sensors or the technology underlying them is fundamental to the monitoring mode. This paper presents a critical review of the fundaments and applications of sensing technologies for SHM systems employing ESs, focusing on their actual developments and innovation, as well as analysing the challenges that these technologies present, in order to build a path that allows for a connected world through distributed measurement systems.

No abstract

There are increasing environmental and economic demands for the production of chemicals of industrial interest from renewable resources. Among the renewable products, short‐chain carboxylic acids (C1‐C6) stand out due to their importance in many sectors of the economy. Within this class, a wide variety of acids are industrially valuable as the precursors of many other chemicals for different applications, technological solutions, and markets. This makes it difficult to identify the most promising from a technical and economic standpoint. In this work, data on scientific papers and patents published between 2008 to 2017, related to the main bio‐based carboxylic acids, are used to identify the acids that are generating growing scientific and industrial interest. The biochemical processes in patents associated with the production of such acids are evaluated using a multicriteria approach that integrates valuation patent criteria. The results of this study show that acids that are of substantial commercial interest, such as acetic, citric, lactic, acrylic, and methacrylic acids, have the highest growth rate both in scientific papers and patents. In terms of biochemical processes, the multicriteria decision analysis showed that the most relevant processes described in patents were associated with ‘drop‐in’ acids such as methacrylic, adipic, maleic, acrylic, and glutaric acids. There is also a clear indication of the emergence of studies on low volume acids such as acetoacetic, acetolactic, muconic, and levulinic acids. In conclusion, the analysis shows that emerging scientific and technological production is conservative, focusing on acids with established markets, especially for the substitution of petrochemicals for immediate demand. © 2020 Society of Industrial Chemistry and John Wiley & Sons Ltd

Structural parts’ integrity should remain as specified and designed, although it can change due to ageing and use by environmental action and accidental events. Structural parts design is carried out considering certain service conditions that can be different from operating conditions. These parts often experience dynamic solicitations that change in amplitude and frequency over time, which may cause the part’s failure. The part’s real condition can be assessed by Structural Health Monitoring systems, which grant significant social, economic, and environmental impact, as they can reduce maintenance costs and ensure the integrity of the part and its surroundings. This can be performed with an integrated monitoring system comprising sensors, on the surface or embedded, into the components. However, surface sensors are subject to damage, from collisions and/or environmental action, and embedding sensors can be very challenging and may result in a weakened part. A Self-Sensing Material (SSM) was developed based on piezoelectric particles embedded in metal parts by a solid-state processing technology. The material can act as a sensor and continuously monitor its condition. The SSM's generates an electrical voltage signal when subject to strain stimulus. Moreover, the solid-state processing technology employed promotes mechanical properties enhancement in the processed zone, not only by the grain size reduction but also due to the incorporation of the piezoelectric particles. The response to a set of dynamic loads was assessed and was found to be coherent with the solicitations applied.

Surface metal matrix composites offer an excellent solution for applications where surface properties play a crucial role in components’ performance and durability, such as greater corrosion resistance, better wear resistance, and high formability. Solid-state processing techniques, such as friction surfacing and friction stir welding/processing, offer several advantages over conventional liquid-phase processing methods. This research investigated the feasibility of producing surface composites of aluminium-based dissimilar alloys reinforced with functional microparticles through experimental validation, determined the process parameters that resulted in a more homogeneous distribution of the particles in the surface composites, and enhanced the understanding of Upward Friction Stir Processing (UFSP) technology. The production of aluminium-based dissimilar alloys (AA 7075-T651 and AA 6082-T651) surface composites reinforced with SiC particles was studied, and it was concluded that the macrography and micrography analyses, scanning electron microscopy (SEM) analysis, microhardness measurements, and eddy currents technique reveal an extensive and homogeneous incorporation of SiC particles. In the stirred zone, a decrease of approximately 20 HV 0.5 in hardness was observed compared to the base material. This reduction is attributed to the weakening effect caused by low-temperature annealing during UFSP, which reduces the strengthening effect of the T651 heat treatment. Additionally, the presence of particles did not affect the surface composite hardness in the stirred zone. Furthermore, despite the presence of significant internal defects, SEM analyses revealed evidence of the lower alloy merging with the upper zone, indicating that the lower plate had a role beyond being merely sacrificial. Therefore, the production of bimetallic composites through UFSP may offer advantages over composites produced from a monometallic matrix. The results of the eddy currents testing and microhardness measurements support this finding and are consistent with the SEM/EDS analyses.