To improve electromagnetic wave (EMW) absorption performance, a novel nano-laminated Dy₃Si₂C₂ coating was successfully in situ coated on the surface of SiC whisker (SiC_w/Dy₃Si₂C₂) using a molten salt approach. A labyrinthine three-dimensional (3D) net was constructed by the one-dimensional (1D) SiC_w coated with the two-dimensional (2D) Dy₃Si₂C₂ layer with a thickness of ~100 nm, which significantly improved the EMW absorption properties of SiC_w. Compared to pure SiC_w with the minimum reflection loss (RL_min) value of −10.64 dB and the effective absorption bandwidth (EAB) of 1.04 GHz for the sample with a thickness of 4.5 mm, SiC_w/Dy₃Si₂C₂ showed a significantly better EMW absorption performance with RL_min of −32.09 dB and wider EAB of 3.76 GHz for thinner samples with a thickness of 1.76 mm. The enhancement of the EMW absorption performance could be ascribed to the improvement of impedance matching, enhanced conductance loss, interfacial polarization as well as multiple scattering. The SiC_w/Dy₃Si₂C₂ can be a candidate for EMW absorber applications due to its excellent EMW absorption performance and wide EAB for relatively thin samples, light weight, as well as potential oxidation and corrosion resistance at high temperatures. Full article

Concern about the harmful effects that ultraviolet (UV) rays have on the skin of people who are routinely exposed to solar radiation has driven the industry of skin protection creams, sunglasses and clothing. Spanish Navy personnel are subject to different levels of exposure depending on their rank and function. The objective of this research is to analyze the behavioral variables associated to the effects on the skin caused by UV rays, denoted by the combined effects of perceived susceptibility and perceived severity, on their decision to purchase and wear uniforms with UV protection. A confirmatory analysis using a structural equation modeling (SEM) was performed on a sample of 100 respondents. The model results revealed a strong mediating characteristic of the intention to use, variable associated with the exogenous variables. Attitude towards the use of clothing and social influence, as well as the exogenous variable clothing action planning, on the sun protective clothing use during tactical maneuvers. These relationships were significant with p-values close to zero. However, exogenous variables related to perceived susceptibility and perceived severity in exposure to sunlight did not represent a significant influence when mediated by self-efficacy in use. The results revealed the consequence of awareness about the importance of protecting oneself and the influence that usage habits can have on the military with respect to the decision to purchase uniforms with UV protection. Full article

Thermo-responsive shape memory materials were developed based on recycled ethylene-propylene-diene (EPDM) rubber shred and thermoplastic elastomers (TPE). Ethylene-1-octene TPEs (Engage 8180, 8411, 8452) with varying degrees of crystallinity and Mooney viscosity were used to prepare the composite materials. To avoid the deterioration of static mechanical properties after mixing recycled EPDM rubber shred (RS) with thermoplastic elastomers, they were partially cured using dicumyl peroxide. The peroxide curing was the most effective for a rubber shred/Engage 8180 blend, where the highest cure rate index (CRI), 1.88 dNm⋅min⁻¹, was observed. The curing caused an approximately 4-fold increase of tensile strength (TS) values for EPDM rubber shred/thermoplastic elastomer blend to the level acceptable for the rubber industry compared with an uncured blend. The incorporation of EPDM rubber shred changed thermoplastic elastomers’ viscoelastic behavior, increasing the values of storage (G′) and loss (G″) modulus. The lowest viscosity of molten Engage 8411 during mixing led to higher compatibility of rubber shred RS/8411 blend, as confirmed by analysis of Cole-Cole plots and the blend morphology. All rubber shred RS/TPE blends showed the shape memory behavior. For the RS/Engage 8452 blend, the highest shape fixity (F) value (94%) was observed, while the shape recovery (RR) was 87%. Studies confirmed that the intelligent materials with shape memory effect could be obtained via selectively chosen thermoplastic elastomers; ethylene-1-octene as a binder for recycled EPDM. Prepared recycled TPE/rubber shred blends can be successfully reused due to their viscoelastic and mechanical properties. Therefore, such a concept can be potentially interesting for the rubber industry. Full article

The increase in the number of revision surgeries after a total knee replacement surgery reaches 19%. One of the reasons for the majority of revisions relates to the debris of the ultra-high molecular weight polyethylene that serves to facilitate the sliding between the femoral and tibial components. This paper addresses the biomechanical properties of ULTEM^TM 1010 in a totally new knee replacement design, based on one of the commercial models of the Stryker manufacturer. It is designed and produced through additive manufacturing that replaces the tibial component and the polyethylene in such a way as to reduce the pieces that are part of the prosthetic assembly to only two: the femoral and the tibial (the so-called “two-component knee prosthesis”). The cytotoxicity as well as the live/dead tests carried out on a series of biomaterials guarantee the best osteointegration of the studied material. The finite element simulation method guarantees the stability of the material before a load of 2000 N is applied in the bending angles 0°, 30°, 60°, 90°, and 120°. Thus, the non-metallic prosthetic material and approach represent a promising alternative for metal-allergic patients. Full article

The textile sector produces yearly great quantities of cotton byproducts, and the major part is either incinerated or landfilled, resulting in serious environmental risks. The use of such byproducts in the composite sector presents an attractive opportunity to valorize the residue, reduce its environmental impact, and decrease the pressure on natural and synthetic resources. In this work, composite materials based on polypropylene and dyed cotton byproducts from the textile industry were manufactured. The competitiveness of the resulting composites was evaluated from the analyses, at macro and micro scales, of the flexural modulus. It was observed that the presence of dyes in cotton fibers, also a byproduct from the production of denim items, notably favored the dispersion of the phases in comparison with other cellulose-rich fibers. Further, the presence of a coupling agent, in this case, maleic anhydride grafted polypropylene, enhanced the interfacial adhesion of the composite. As a result, the flexural modulus of the composite at 50 wt.% of cotton fibers enhanced by 272% the modulus of the matrix. From the micromechanics analysis, using the Hirsch model, the intrinsic flexural modulus of cotton fibers was set at 20.9 GPa. Other relevant micromechanics factors were studied to evaluate the contribution and efficiency of the fibers to the flexural modulus of the composite. Overall, the work sheds light on the potential of cotton industry byproducts to contribute to a circular economy. Full article

In this study, experimental analysis on the compressive strength of multi-leaf thin-tile masonry is presented. A compressive strength test was carried out on thin-tile, mortar and 48 specimens with two- and three-leaf thin-tile masonry. The results obtained were compared with literature on brick masonry loaded parallel to a bed joint. Based on the results of this study, the failure mode presented the first crack in the vertical interface; this crack grew until the leaf was detached. From this point until collapse, lateral buckling of the leaves was generally observed. Therefore, the detachment compressive strength value was considered relevant. Up to this point, both masonries exhibit similar stress–strain behavior. The experimental values of the detachment compressive strength were compared with the values calculated from the equation generally used in the literature to evaluate the compressive strength of brick masonry. From the results obtained, the following conclusion can be drawn: This equation is only suitable for tree-leaf thin-tile masonry but with more relevant influence on the compressive strength of the mortar. This study concluded that only three-leaf specimens behave similarly to brick masonry loaded parallel to a bed joint. Finally, whether the failure mode was due to shear or tensile stresses in the vertical thin-tile-mortar interface cannot be identified. Full article

This paper presents an experimental study investigating the corrosion damage of carbon-steel fibre reinforced concrete (SFRC) exposed to wet–dry cycles of chlorides and carbon dioxide for two years, and its effects on the mechanical performance of the composite over time. The results presented showed a moderate corrosion damage at fibres crossing cracks, within an approximate depth of up to 40 mm inside the crack after two-years of exposure, for the most aggressive exposure conditions investigated. Corrosion damage did not entail a significant detriment to the mechanical performance of the cracked SFRC over the time-scales investigated. Corrosion damage to steel fibres embedded in uncracked concrete was negligible, and only caused formation of rust marks at the concrete surface. Overall, the impact of fibre damage to the toughness variation of the cracked composite over the time-scale investigated was secondary compared to the toughness variation due to the fibre distribution. The impact of fibre corrosion to the performance of the cracked composite was subject to a size-effect and may only be significant for small cross-sections. Full article

Glass fibre is the most widely used material for reinforcing thermoplastic matrices presently and its use continues to grow. A significant disadvantage of glass fibre, however, is its impact on the environment, in particular, due to the fact that glass fibre-reinforced composite materials are difficult to recycle. Polyamide 6 is an engineering plastic frequently used as a matrix for high-mechanical performance composites. Producing polyamide monomer requires the use of a large amount of energy and can also pose harmful environmental impacts. Consequently, glass fibre-reinforced Polyamide 6 composites cannot be considered environmentally friendly. In this work, we assessed the performance of a road cycling pedal body consisting of a composite of natural Polyamide 11 reinforced with lignocellulosic fibres from stone-ground wood, as an alternative to the conventional glass fibre-reinforced Polyamide 6 composite (the most common material used for recreational purposes). We developed a 3D model of a pedal with a geometry based on a combination of two existing commercial choices and used it to perform three finite-element tests in order to assess its strength under highly demanding static and cyclic conditions. A supplementary life cycle analysis of the pedal was also performed to determine the ecological impact. Based on the results of the simulation tests, the pedal is considered to be mechanically viable and has a significantly lower environmental impact than fully synthetic composites. Full article

In this study, the human-induced dynamic performance of modern footbridges equipped with either classical reinforced concrete (RC) or innovative glass fiber-reinforced polymer (GFRP) composite deck slabs were investigated and compared. The numerical studies were carried out for two bridges: a three-span cable-stayed footbridge and a three-span continuous beam structure. Two variants of both bridges were taken into consideration: the footbridges equipped with traditional RC slabs and the structures benefitted with GFRP slabs. The risk of resonance as well as the vibration serviceability and the comfort criteria assessment of the footbridges with different slab materials were assessed. The investigation revealed that the footbridges, both cable-stayed and beam, benefitted with the GFRP slabs had higher fundamental frequency than those with the traditional RC slabs. The footbridges with the GFRP slabs were less exposed to the resonance risk, having fundamental frequencies above the limit of the high risk of resonance. The effect of shifting up the natural frequencies by introducing GFRP slabs was more remarkable for the lightweight beam structure than for the cable-stayed footbridge and resulted in a more significant reduction of the resonance risk. The calculated maximum human-induced accelerations of the footbridges benefitted with the GFRP slabs were meaningfully higher than those obtained for the footbridges with the RC slabs. The study proved that, with the same GFRP slab, meeting vibration serviceability and comfort criteria limits in the case of very lightweight beam structures may be more problematic than for cable-stayed footbridges with more massive structural systems. In the research, particular attention was paid to examining the impact of higher harmonics of the moving pedestrian force on the structures benefitted with the GFRP composite slabs. It occurred that in the case of footbridges, both cable-stayed and beam, equipped with the RC slabs higher harmonics of human force did not play any role in the dynamic performance of structures. However, in the case of the footbridges benefitted with the GFRP slabs, the impact of higher harmonics of the pedestrian force on the dynamic behavior of structures was clearly visible. Higher harmonics excited accelerations comparable to those executed by the first harmonic component. This conclusion is of great importance for footbridges equipped with GFRP slabs. The fundamental frequency may place a footbridge in the low or even negligible risk resonance range and the higher frequencies corresponding to vertical modes may be located above the limit of 5 Hz that ensures avoiding resonance. Nevertheless, the fact that fundamental modes are so responsive to higher harmonics significantly increases the risk of resonance. The amplification of the dynamic response may occur due to frequencies related to second or third harmonics (i.e., being half or a third of the natural frequencies). In such cases, full dynamic analysis of a footbridge at the design stage seems to be of crucial importance. Full article