Interlaminar delamination damage is a common and typical defect in the context of structural damage in carbon fiber-reinforced resin matrix composites. The technology to identify such damage is crucial for improving the safety and reliability of structures. In this paper, we fabricated carbon fiber-reinforced composite laminates with different degrees of delamination damage, conducted static load experiments on them and used femtosecond fiber Bragg grating sensors (fsFBG) to determine their structural state to investigate the effects of delamination damage on their performance. We constructed a model to identify damage based on the deep residual shrinkage network, and used experimental data to enable it to identify varying degrees of delamination damage to carbon fiber-reinforced composites with an accuracy of 97.98%.

Natural sepiolite has great potential for application in wound healing, haemostasis and medicines. This paper introduces a versatile solid-state sintering technique for preparing sepiolite-based nanocomposites with enhanced antibacterial properties, and the physical, structural, rheological and antibacterial properties of which were determined to be enhanced. The incorporation of nanosized Ag and metal oxides into sepiolite composites results in a notable improvement in their antibacterial efficacy against Escherichia coli and Staphylococcus aureus in comparison to the unmodified sepiolite. With a low silver content of just 5%, the sepiolite–Ag composite achieves an antibacterial rate of ~100%. Furthermore, the rheological properties exhibited by the sepiolite composites are noteworthy, suggesting their suitability for use in wound-dressing applications due to their exceptional workability. The methodology employed in this research has the potential to offer a viable substitute for the production of economical and effective natural antibacterial nanocomposites.

This paper studies the aeroelasticity of a stiffened cantilever plate using composite material and novel structural layouts. A comprehensive parametric study is conducted to determine the influence of different design parameters on the aeroelastic boundaries. Design parameters include plate sweep angle, ply orientation, stringer cross-section and stringer sweep angle. Nastran is used to run the aeroelastic analysis, and the process is automated using ${\rm{Matla}}{{\rm{b}}^{}}$. The structure of the plate is modelled using laminate elements whereas the stringers are modelled using the Euler-Bernoulli beam elements. The unsteady aerodynamic loads are modelled using doublet-lattice method (DLM) and the structural and aerodynamic meshes are connected using an infinite plate surface (IPS) spline. A mesh sensitivity analysis is conducted to ensure fine meshes for the aerodynamics and structure. The study’s findings demonstrate the benefits of employing forward swept (Fw) stringers since it increases flutter speed by almost 38% compared to the unswept stringers case and prevents divergence. Moreover, the static aeroelastic analysis illustrates that the utilisation of Fw swept stringers can reduce the average tip displacement and tip twist effectively. T-shaped stringers are recommended to stiffen the plate due to their lower impact on the total mass of the plate. In some configurations, the structural layout has a much higher effect on the aeroelastic instabilities when compared to the material effect (ply orientation). However, results suggest combining both for some cases to get balanced washin and washout effects.

In order to extend the application of magadiite to optical fields (rather than the usual focus on adsorption, catalysis, ion exchange, etc.), a magadiite-CdS (Mag-CdS) composite was synthesized from Na-magadiite by ion exchange. Various techniques were used to characterize the composite. X-ray diffraction results indicated that the Mag-CdS composite retained the host magadiite structure in spite of decrease in the intensity of the X-ray diffraction peak of the host magadiite. The analytical results confirmed the formation of the Mag-CdS composite, along with the modification of the optical properties of CdS by the host magadiite.

Truss structures are a stiff, economical, and efficient lightweight design, the limiting factor of these structures are usually the load transfer elements. This paper presents an analytical design method for optimized adhesive tubular lap joints between CFRP tubes and aluminium inserts. The analytically optimized design agrees very well with the numerical simulations and experimental results. Although the experiments show a highly non-linear behaviour, where a linear elastic correlation is expected, the total load capacity is only reached when the adhesive is fully plasticised.

This paper presents the design, manufacturing and experimental assessment of a morphing element consisting of a composite corrugated panel that hosts a diffused actuation system based on Shape Memory Alloy (SMA) actuators. The characterisation of the SMA actuators is reported and the system performance is predicted through an analytical model and finite element analyses. Two versions of the actuated system are proposed, with different methods for the physical integration of the SMA wires into the composite part. Manufacturing and testing of specimens with different wire densities are reported. Correlation with experiments validates the analytical and numerical approaches adopted for the design and analyses. The results confirm the potential of the concept proposed for developing corrugated panels that can be contracted in a predefined direction by a load-bearing actuation system, but still retain high stiffness and strength properties in other directions.

Electrophoretic deposition consisting of bioglass (BG)–chitosan (CS)–iron oxide nanoparticles (Fe3O4 NPs) on the Ti–13Nb–13Zr substrate was described. The bioactive coating was embedded in a CS matrix. The Fe3O4 NPs collected using the co-precipitation method varied at three different levels (1, 3, and 5 wt%) in the BG coating. The formulated coatings exhibited a hydrophilic character due to higher surface roughness values. The pull-off tape test was performed to check the adhesion strength of coatings. The composite coatings displayed adhesion strength of 5B class. The corrosion behavior was evaluated in Ringer's solution by the electrochemical test. The corrosion results showed that the composite coatings were more impressive as compared to pure BG and Fe3O4 coatings. The hemocompatibility results showed a hemolytic ratio (<5%), which validates them as favorable blood compatible nature of the deposited coatings. The findings exhibited that the BG–Fe3O4–CS coating can be widely employed as a favorable material for orthopedic applications.

Nano-sized TiN-reinforced Ti metal matrix composites were fabricated by powder metallurgical route, which includes high-energy ball milling pretreatment and subsequent hot-press sintering treatment. The phase composition and microstructure of the sintered samples were characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. Results showed that N2 was absorbed and solubilized into TiH2 by milling pretreatment, and TiN was formed during sintering process and was fine to a grain size of 20–100 nm. The final phase composition of the composites was αTi, βTi, and TiN with solution N in matrix. Mechanical tests showed that with increasing milling time, the hardness of the composites increased by 31, 58, 93, and 101% compared with pure Ti. The compressive strength initially increased and later decreased to 2440 and 2120 MPa when milled for 1.5 and 2 h, respectively.

There is increased interest in the use of cellulose nanomaterials for the mechanical reinforcement of composites due to their high stiffness and strength. However, challenges remain in accurately determining their distribution within composite microstructures. We report the use of a range of techniques used to image aggregates of cellulose nanocrystals (CNCs) greater than 10 µm2 within a model thermoplastic polymer. While Raman imaging accurately determines CNC aggregate size, it requires extended periods of analysis and the limited observable area results in poor reproducibility. In contrast, staining the CNCs with a fluorophore enables rapid acquisition with high reproducibility, but overestimates the aggregate size as CNC content increases. Multi-channel spectral confocal laser scanning microscopy is presented as an alternative technique that combines the accuracy of Raman imaging with the speed and reproducibility of conventional confocal laser scanning microscopy, enabling the rapid determination of CNC aggregate distribution within composites.

Effects of varying volume fractions of SiC nanoparticle (SiCNP) reinforcement on microstructure and mechanical properties of dissimilar AA2024-T351 and AA7075-T651 joints by friction stir welding (FSW) have been investigated experimentally. A rectangular section edge groove was prepared at the adjoining surfaces of the two plates with the butt configuration before FSW. Initially, four fractional volumes with 0, 5, 8, and 13% of SiCNP are reinforced into the grooves of width, 0, 0.2, 0.3, and 0.5 mm and the FSW was performed with the first and second pass to obtain metal matrix nanocomposite (MMNC) at the weld nugget zone (WNZ). The characterization of microstructure specimens was investigated using optical microscopy (OM), scanning electron microscopy (SEM) and X-ray diffraction technique (XRD). The FSW joint specimen produced with 5 vol% fraction of SiCNP for second pass processing observes a defect-free, homogeneous distribution of SiCNP with a mean grain size of about 2–3 µm at the WNZ and weld joints higher in tensile strength, 411 MPa, yield strength, 252 MPa, and percentage elongation, 14.3. The result shows that varying volume fractions (5, 8, 13%) of the SiCNP after the FSW second pass led to significant grain refinement at the WNZ and higher mechanical properties compared with FSW specimens prepared without SiCNP. Higher hardness of 150 Hv was observed in the WNZ for specimen produced with 13 vol% fraction SiCNP.

The rotorcraft industry needs Virtual Engineering first to ensure decisions made early in the life-cycle, at the requirements capture and preliminary design phases for example, are reliably informed. Later, in design, development and qualification, Virtual Prototypes can become the centre of attention for critical reviews and, ultimately, certification itself. A significant challenge is to ensure that model fidelity is good enough, not only for supporting design decisions but also in establishing requirements based on sufficiently mature technologies. This international conference, Rotorcraft virtual engineering; supporting life-cycle engineering through design and development, test and certification and operations and co-sponsored by the RAeS/AHS/A3F/DGLR/AIDAA addressed these themes and this paper reviews and assesses the value of the various contributions.

This study investigated the potential of halloysite nanotubes (HNTs) to improve the sustained release properties of chitosan (CS) microparticles cross-linked ionically with tripolyphosphate (TPP). Composite CS-HNTs microparticles were obtained by a simple and eco-friendly procedure based on a coaxial extrusion technique. Prior to encapsulation, a water-soluble model drug, verapamil hydrochloride (VH), was adsorbed successfully on HNTs. The microparticles were characterized by optical microscopy, Fourier transform infrared (FTIR) spectroscopy, differential thermal analysis/ thermogravimetric analysis (DTA/TG) and evaluated for encapsulation efficiency and drug-release properties. The composite particles had a slightly deformed spherical shape and micrometric size with average perimeters ranging from 485.4 ± 13.3 to 492.4 ± 11.9 μm. The results of FTIR spectroscopy confirmed non-covalent interactions between CS and HNTs within composite particle structures. The DTA and TG studies revealed increased thermal stability of the composite particles in comparison to the CS-TPP particles. Drug adsorption on HNTs prior to encapsulation led to an increase in encapsulation efficiency from 19.6 ± 2.9 to 84.3 ± 1.9%. In contrast to the rapid release of encapsulated model drug from CS-TPP microparticles, the composite CS-HNTs microparticles released drug in a sustained manner, showing the best fit to the Bhaskar model. The results presented here imply that HNTs could be used to improve morphology, encapsulation efficiency and sustained drug-release properties of CS microparticles cross-linked ionically with TPP.

In order to improve the optical properties and enhance the stability of Zn1–xCdxS nanoparticles, which are important optoelectrical materials, the ternary Zn1–xCdxS nanoparticles were enclosed in a layered octosilicate by a three-step process, namely (i) protonation of Naoctosilicate, (ii) ion-exchange in order to introduce Zn and Cd ions into the interlayer space, and (iii) addition of S2– to form Zn1–xCdxS particles in the interlayer space of the octosilicate. The basal spacing (~10 Å) of the final ZnCdS-Oct-n (n = 1, 2, 3, 4) composites noticeably increased in comparison with that of the precursor H-Oct (7.5 Å). This may be attributed to the incorporation of larger size Zn1–xCdxS particles into the interlayer space of H-Oct. The UV-visible spectra of the composites suggested that the transmission band-edges gradually shifted to low energy with increasing molar ratio of Cd/Zn. Moreover, the transmission band-edges of the composites are between those of layered Octosilicate, ZnS, and CdS. TEM observation confirmed that the size of Zn1–xCdxS nanoparticles enclosed in the layered silicate was about ~3–5 nm.

The paper analyzes the issues relating to the applicability of innovative material systems for flexible composite armors. The authors made several samplings of aramid fibers (Kevlar 49) by replacing the epoxy resin base, which is often described in the literature, with the thermoplastic matrix - polyethylene (HDPE) and polypropylene (PP). The samples were fired with .38 Special Full Metal Jacketed (FMJ) ammunition produced by the S&B Company, and then the process of firing was modeled in the ABAQUS program. The advantages and disadvantages of the new material system including the possibility of its use in the construction of hybrid composite armors have been presented on the basis of the results of numerical analyses and ballistic tests.

This article presents innovative work undertaken to evaluate the auxetic composite materials developed using weft-knitted fabrics with negative Poisson’s ratio (NPR) produced from high-tenacity filaments of para-aramid (p-AR) and polyamide. The aim of this study is to develop polymeric composite materials reinforced with auxetic knitted fabrics and to evaluate the degree of transference of the auxetic behavior from the fibrous reinforcement to the composite produced. The results show that the NPR values remained in the composites. Regardless of the type of resin used, either epoxy or polyester, the highest values were obtained for samples produced with p-AR auxetic knitted fabrics. The NPR composites developed within this work present great potential for applications in industrial areas, including personal protection products, such as bulletproof vests, helmets, knee, and elbow protectors, and in all other areas where energy absorption is a key factor to be considered.

The ever-changing battlefield environment, as well as the emergence of global command and control architectures currently used by armed forces around the globe, requires the use of robust and adaptive technologies integrated into a reliable platform. Unmanned Combat Aerial Vehicles (UCAVs) aim to integrate such advanced technologies while also increasing the tactical capabilities of combat aircraft. This paper provides a summary of the technical and operational design challenges specific to UCAVs, focusing on high-performance, and stealth designs. After a brief historical overview, the main technology demonstrator programmes currently under development are presented. The key technologies affecting UCAV design are identified and discussed. Finally, this paper briefly presents the main issues related to airworthiness, navigation, and ethical concerns behind UAV/UCAV operations.