Innovative Fusion Strategy for MEMS Redundant-IMU Exploiting Custom 3D Components.

In recent years, the overall performances of inertial Micro-Electro Mechanical Sensors (MEMSs) exhibited substantial improvements to values very close or similar to so-called tactical-grade sensors. However, due to their high costs, numerous researchers are currently focusing on the performance enhancement of cheap consumer-grade MEMS inertial sensors for all those applications (as an example, small unmanned aerial vehicles, UAVs), where cost effectiveness is a relevant request; the use of redundancy proves to be a feasible method for this purpose. In this regard, the authors propose, hereinafter, a suitable strategy aimed at fusing raw measurements provided by multiple inertial sensors mounted on a 3D-printed structure. In particular, accelerations and angular rates measured by the sensors are averaged according to weights associated with the results of an Allan variance approach; the lower the noise figure of the sensors, the greater their weight on the final averaged values. On the other hand, possible effects on the measurements due to the use of a 3D structure in reinforced ONYX (a material capable of providing better mechanical specifications for avionic applications with respect to other solutions for additive manufacturing) were evaluated. The performance of a prototype implementing the considered strategy is compared with that of a tactical-grade inertial measurement unit in stationary conditions, exhibiting differences as low as 0.3 degrees in heading measurements. Moreover, the reinforced ONYX structure does not significantly affect the measured values in terms of both thermal and magnetic field while assuring better mechanical characteristics with respect to other 3D printing materials, thanks to a tensile strength of about 250 MPa and a specific stacking sequence of continuous fibers. Finally, a test conducted on an actual UAV highlights performance very close to that of a reference unit, with root-mean-square error in heading measurements as low as 0.3 degrees in observation intervals up to 140 s.

Effect of Vegetable Oil on the Properties of Asphalt Binder Modified with High Density Polyethylene.

Economic development results in increased traffic and higher traffic loads that often cause serious asphalt pavement problems, such as permanent deformation, fatigue cracking, and reduced lifetime. Polymers are seen as viable asphalt additives to minimize these problems. However, their incorporation reduces the workability of the material due to the increase in the viscosity of the blend. This study evaluates the effect of the addition of soybean oil on the physical, rheological, and thermal properties of high-density polyethylene (HDPE)-modified asphalt binder. The HDPE was kept at 5 wt.% and the soybean oil the asphalt was varied from 1 to 7 wt.%. A series of tests was conducted to evaluate the binders, comprising conventional tests (penetration, softening point, and ductility) rheological performance tests (dynamic viscosity and short-term aging (RTFO), and thermogravimetric analysis (TGA). The addition of HDPE reduced the penetration and increased the softening point and viscosity. The oil reduced steadily the viscosity, improved the workability and the thermal susceptibility of the modified asphalt up to 3 wt.% of oil, and reduced about 92% mass gain after aging. Hence, the oil is considered a good modifier agent for the improvement of polymer-modified asphalt's workability under service conditions.

Influence of Fibre Fill Pattern and Stacking Sequence on Open-Hole Tensile Behaviour in Additive Manufactured Fibre-Reinforced Composites.

Additive manufacturing has revolutionised the field of manufacturing, allowing for the production of complex geometries with high precision and accuracy. One of the most promising applications of additive manufacturing is in the production of composites, which are materials made by combining two or more substances with different properties to achieve specific functional characteristics. In recent years, the use of Continuous Filament Fabrication (CFF) in additive manufacturing has become increasingly popular due to its ability to produce high-quality composite parts which have fibres with a complex orientation and high curvature. This paper aims to investigate the influence of fill pattern and stacking sequence on the open-hole tensile strength of composites manufactured using CFF and made of an innovative matrix composed of nylon and short carbon fibres, i.e., Onyx, and with continuous carbon fibre as reinforcement. By systematically varying the fill pattern and stacking sequence, we aim to identify the optimal combination that can achieve the highest open-hole tensile strength in these composites. The results of this study will provide valuable insights into the design and manufacture of high-strength composites using additive manufacturing. Open-hole strength and elastic properties are strongly influenced by the infill strategy and stacking sequences adopted, and show different failure modes. The results also point out a technological issue characterising the process and indicate some guidelines for designing and manufacturing 3D printing composites.

Effectiveness of Mesoporous Silica Nanoparticles Functionalized with Benzoyl Chloride in pH-Responsive Anticorrosion Polymer Coatings.

Smart polymer coatings embedding stimuli-responsive corrosion inhibitor nanocarriers are commonly exploited, in the literature, for the development of high-performance active coatings. In this work, high-surface-area amino-functionalized mesoporous silica nanoparticles (MSN-NH2) were developed with a one-step synthesis process and then functionalized with benzoyl chloride (MSN-BC) through a reaction with amino groups. MSN-BC are able to release benzoic acid (BA) in acid and alkaline conditions as a result of the hydrolysis of the pH-sensitive amide bond. MSN-BC were embedded in polymer coatings to exploit the pH-dependent release of corrosion-inhibiting BA. After an in-depth characterization of the developed functional nanoparticles and of their pH-dependent release kinetics of BA, MSN-BC were embedded in an acrylic matrix, realizing coatings for the corrosion protection of aluminum AA2024 alloys. Results demonstrate the effectiveness of the nanoparticles' porous structure for a high loading of the anticorrosive active agent BA and the long-lasting efficiency of the coating for the corrosion protection of aluminum alloys, as validated by morphological and electrochemical impedance spectroscopy (EIS) measurements. EIS experiments were carried out with up to 21 days of exposure to a corrosive environment, revealing the potentialities of the acrylic coatings embedding MSN-BC for the protection of aluminum alloys.

Mechanical and microstructural characterization of titanium gr.5 parts produced by different manufacturing routes.

Since a few decades, the aircraft industry has shifted its preference for metal parts to titanium and its alloys, such as the high-strength titanium grade 5 alloy. Because of titanium grade 5 limited formability at ambient temperature, forming operations on this material requires high temperatures. In these conditions, a peculiar microstructure evolves as a result of the heating and deformation cycles, which has a significant impact on formability and product quality. On the other hand, additive manufacturing technologies, such as selective laser melting and electron beam melting, are increasingly being used and are replacing more traditional approaches such as machining and forging. Fundamental part characteristics such as mechanical and microstructural properties, geometric accuracy, and surface quality strongly depend on the selection of the manufacturing method. The authors of this paper seek to identify the strengths and limitations imposed by the intrinsic characteristics of different manufacturing alternatives for the production of parts of aeronautical significance, providing guidelines for the choice of the most appropriate manufacturing route for a given application and part design.

Effect of microneedles shape on skin penetration and transdermal drug administration.

Microneedle (MN) patches are highly efficient and versatile tools for transdermal drug administration, in particular for pain-free, self-medication and rapid local applications. Diffraction ultraviolet (UV) light lithography offers an advanced method in fabricating poly(ethylene glycol)-based MNs with different shapes, by changing both the UV-light exposure time and photomask design. The exposure time interval is limited at obtaining conical structures with aspect ratio < 1:3, otherwise MNs exhibit reduced fracture load and poor indentation ability, not suitable for practical application. Therefore, this work is focused on a systematic analysis of the MN's base shapes effects on the structural characteristics, skin penetration and drug delivery. Analyzing four different base shapes (circle, triangle, square and star), it has been found that the number of vertices in the polygon base heavily affects these properties. The star-like MNs reveal the most efficient skin penetration ability (equal to 40 % of -their length), due to the edges action on the skin during the perforation. Furthermore, the quantification of the drug delivered by the MNs through ex-vivo porcine skin shows that the amounts of small molecules released over 24 h by star-like MNs coated by local anesthetic (Lidocaine) and an anti-inflammatory (Diclofenac epolamine) drugs are 1.5× and 2× higher than the circular-MNs, respectively.

Effect of Fibre Orientation on Novel Continuous 3D-Printed Fibre-Reinforced Composites.

Among the several additive manufacturing techniques, fused filament fabrication (FFF) is a 3D printing technique that is fast, handy, and low cost, used to produce complex-shaped parts easily and quickly. FFF adds material layer by layer, saving energy, costs, raw material costs, and waste. Nevertheless, the mechanical properties of the thermoplastic materials involved are low compared to traditional engineering materials. This paper deals with the manufacturing of composite material laminates obtained by the Markforged continuous filament fabrication (CFF) technique, using an innovative matrix infilled by carbon nanofibre (Onyx), a high-strength thermoplastic material with an excellent surface finish and high resistance to chemical agents. Three macro-categories of samples were manufactured using Onyx and continuous carbon fibre to evaluate the effect of the fibre on mechanical features of the novel composites and their influence on surface finishes. SEM (Scanning Electron Microscopy) analysis and acquisition of roughness profile by a confocal lens were conducted. Tensile and compression tests, thermogravimetric analysis and calorimetric analysis using a DSC (differential scanning calorimeter) were carried out on all specimen types to evaluate the influence of the process parameters and layup configurations on the quality and mechanical behaviour of the 3D-printed samples.

Effect of Different Surface Treatments on Titanium Dental Implant Micro-Morphology.

BACKGROUND: Titanium dental implants are today widely used with osseointegration mainly dependently on the implant surface properties. Different processing routes lead to different surface characteristics resulting, of course, in different in situ behaviors of the implants. MATERIALS: The effect of different treatments, whether mechanical or chemical, on the surface morphology of titanium implants were investigated. To this aim, various experimental methods, including roughness analysis as well scanning electron microscope (SEM) observations, were applied. RESULTS: The results showed that, in contrast to the mechanical treatments, the chemical ones gave rise to a more irregular surface. SEM observations suggested that where commercial pure titanium was used, the chemical treatments provided implant surfaces without contaminations. In contrast, sandblasted implants could cause potential risks of surface contamination because of the presence of blasting particles remnants. CONCLUSIONS: The examined implant surfaces showed different roughness levels in relation to the superficial treatment applied. The acid-etched surfaces were characterized by the presence of deeper valleys and higher peaks than the sandblasted surfaces. For this reason, acid-etched surfaces can be more easily damaged by the stress produced by the peri-implant bone during surgical implant placement.

Profilometric and standard error of the mean analysis of rough implant surfaces treated with different instrumentations.

PURPOSE: This study evaluated, in vitro, the effects of different instrumentations used in the treatment of peri-implantitis on implant surfaces coated with hydroxyapatite or titanium plasma spray (TPS). MATERIALS AND METHODS: There were 14 cylindrical rough implants used, including 7 hydroxyapatite and 7 TPS coated. Split in 2 parts for a total of 24 experimental surfaces, implants were treated with a stainless-steel curette, plastic curette, ultrasonic scaler tip, and air-powder-water spray. There was 1 hydroxyapatite and 1 TPS implant used as controls. Profilometry and scanning electron microscopy were used to examine instrumented surfaces for variations in surface topography. RESULTS: All experimental procedures determined changes on tested rough implant surfaces. Such alterations were related to the implant coating material, and the procedure consisting in coating removal and/or leveling of surface roughness. CONCLUSION: Although a plastic curette and air-powder-water spray induced less implant surface alterations, these instrumentations left deposits on the surface that may affect, in vivo, the tissue healing process.