Structures with chiral, antichiral, or metachiral configurations are prominent examples of mechanical metamaterials. Different methods have been introduced to increase the tunability of such structures. However, they are usually limited in the range of achievable mechanical properties. Herein, we present a method to expand the achievable properties significantly by exploring various node-strut connection configurations. Advancing from conventional chiral-based metamaterials, all possible combinations of strut connections to circular nodes with three and four tangentially attached struts were generated and analyzed. Additionally, each structure was investigated with four different node diameters. In this way, a wide range of Young’s moduli, shear moduli and Poisson’s ratios can be achieved. Overall, 294,912 unique unit cell geometries were created. All structures were analyzed by means of numerical homogenization simulations to obtain the full stiffness tensor of each geometry. In this study, we particularly focus on the relationship between the Young’s modulus and its corresponding Poisson’s ratio of orthotropic structures. Selected full-size geometries were also created and simulated with a displacement-controlled extension load case to visualize the deformation behavior.
The controlled integration of multiple immiscible elements into Pt alloy nanoparticles (NPs) to develop novel electrocatalysts presents significant potential for advancing sustainable energy technologies. In this study, we use a simple method for mixing diverse metal elements from their precursor salt solutions to form alloy NPs. The synthesis was carried out by subjecting a mixture of precursor metal salts supported on carbon paper (CP) to thermal shock, rapidly increasing the temperature to similar to 1600 K. By modulating the types and numbers of metal elements, we synthesized multicomponent metal NPs with tailored chemical compositions and sizes. To validate the practical application of this catalyst, we evaluated its hydrogen evolution reaction (HER) activity during water splitting under acidic conditions. The synthesized CP-PtNiRu electrocatalyst demonstrates an overpotential of 30.5 mV at a current density of 10 mA/cm(2), comparable to that of commercial Pt/C electrodes, significantly enhancing the utilization efficiency of Pt-based electrocatalysts.
The prospect of cost reduction, enhanced performance, and improved sustainability has been driving innovation in the development of new backsheet materials for photovoltaic (PV) modules. Among the materials of interest, polypropylene (PP) has emerged as a promising alternative to fluoropolymer backsheets. As backsheets serve as a barrier providing electrical insulation and protection for the sensitive electrical components of PV modules, comprehensive understanding of the durability of PP-based backsheets is essential to ensure module reliability in the field. In this study, free-standing coextruded PP backsheets were subjected to artificial weathering to elucidate the degradation behavior. The UV exposure was performed on the NIST Simulated Photodegradation via High Energy Radiant Exposure (SPHERE) under three environmental conditions: 75 degrees C and 50 % relative humidity (RH), 75 degrees C and 20 % RH, and 65 degrees C and 20 % RH. The total UV dose (295 nm to 400 nm) for each film was approximate to 1710 MJ/ m2, or approximate to 50 years in Arizona, assuming 10 % albedo. Chemical, optical, and physical changes were monitored throughout exposure. Peak-resolving analysis was applied to attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectra to obtain functional group concentrations with respect to exposure. The greatest chemical and physical changes are seen after initial exposure (100 MJ/m2 to 220 MJ/m2), followed by a saturation point. Spectroscopic results indicate minor accumulation of oxidation products and additive migration. Raman spectroscopy showed a slight increase in crystallinity of the surface layers of the backsheets. Mechanical testing revealed low cracking propensity, with shallow cracks occurring under high strains.
Reliable and esthetically pleasing lightweight photovoltaic modules for building integration are expected to grow interest in the consumer market, especially for retrofitting older buildings and storehouses that are not structurally designed to withstand additional dead‐weight. The present work reveals the design of a novel module architecture attaining a total weight <6 kg/m 2 . The approach uses a highly transparent polymeric foil as the front pane and as an encapsulant to maintain optical coupling between the cell and the incident solar radiation, while the mechanical rigidity of module is maintained by the use of a composite backsheet, which consists of a polypropylene‐based honeycomb sandwiched between two layers of fiber reinforced skins. Two polypropylene skin variants were evaluated, with fiber densities of 820 and 660 g/m 2 . For esthetical improvement of the lightweight PV modules, a colored interlayer foil was used. Reliability testing included flexural bending and static mechanical load tests, environmental tests like, damp‐heat, ultraviolet radiation, thermal cycling, and humidity freeze. Several other critical tests, like hail‐impact test and fire‐ignition test, were also performed to check the potential of these architectures for building integration. The fiber density in skins of composite backsheets impacted the performance of modules against mechanical loads.
This review synthesizes recent progress in femtosecond (fs) laser drilling of epoxy composites, focusing on three interconnected themes critical for industrial scalability: ablation threshold dynamics, multiscale modeling, and adaptive process control. It quantifies how incubation effects reduce multi-pulse ablation thresholds, enabling precise material removal with minimal heat-affected zones. A unified multiscale simulation framework is presented, integrating continuum models, molecular dynamics, and plasma simulations to capture ultrafast energy deposition and stress evolution across vast spatiotemporal scales. To overcome throughput limitations, advanced process control strategies leveraging multimodal diagnostics and machine learning are discussed, demonstrating sub-micron precision and enhanced efficiency. The review concludes by identifying key challenges, such as the need for standardized characterization methods and low-latency feedback systems, and outlines a roadmap for future research, emphasizing the potential for femtosecond laser drilling in high-precision manufacturing applications.
