Conventional diaphragm compressors are fundamentally limited by the low displaced volume and poor fatigue life of their flat metal diaphragms. This study presents a comprehensive, numerical and experimental investigation of the design, manufacturing, and performance of pre-formed, bistable dome-shaped membranes to overcome these limitations. A complete process chain was modeled using the finite element method (FE), simulating the hydroforming process, subsequent elastic springback, and the operational folding cycle. The model was based on the characterization of the anisotropic material properties of high-strength stainless steel foil made of 1.4310 in a spring-hard condition. To validate the simulation, prototypes were manufactured via hydroforming and their final geometries were analyzed using an optical 3D scanning system, showing improved results using the anisotropic material model compared the isotropic. X-ray diffraction (XRD) analysis was applied to quantify induced martensite transformation as part of the material hardening behavior. Subsequent, fatigue life testing was performed on the manufactured membranes to assess their durability under cyclic loading. The results demonstrate that the hydroforming process yields a robust component with superior performance. The optimized hydroformed diaphragm successfully endured over 5 million cycles without failure and enabled an increase of 60% in displaced volume compared to a conventional flat membrane. This integrated design and validation methodology provides a clear pathway for developing next-generation, high-performance diaphragm compressors.

This paper innovatively proposes a combined process combining ultrasonic vibration (abbreviated UV) with creep age forming (abbreviated CAF), named UVCAF, for high-quality forming of dissimilar 7055-T6/2197-T8 FSWed T-stiffened plates. And based on this, a multi-objective optimization quality comprehensive evaluation model of the AMOGA-EWM algorithm is proposed, obtaining the optimal process parameter solution combination as [164.8 °C, 9.2 h, 9.6 μm]. The reliability and feasibility of the above evaluation model in improving the forming rate and mechanical properties for the T-stiffened plates are verified. Meanwhile, through comparative analysis of the experimental results of UVCAF under the optimal process parameters, it is found that the forming rate, tensile strength, and elongation of T-stiffened plates under UVCAF are 5.4%, 12.3 MPa, and 0.82% higher than those under CAF. In addition, the microscopic analysis results indicate that the fracture mode of the specimens under CAF and UVCAF is a ductile fracture, and the weld nugget zone of the specimens under CAF and UVCAF is the combined reinforcement of the T 1 and η phase. However, the introduction of UV through the strengthening effect of fine grains makes the η phase more abundant in UVCAF specimens, thereby improving the forming accuracy and performance of the specimens.

This review traces the evolution of low-density steels (LDS) and highlights the key mechanisms that link processing routes to microstructural evolution and performance. Beyond fabrication methods, the article emphasizes the fundamental insights that have emerged, particularly the roles of metal carbide/intermetallic network control, segregation mitigation, and grain refinement that govern the unique behavior of LDS across processing routes in achieving superior mechanical behavior. A key insight from the literature is the exceptional potential of mechanical alloying combined with spark plasma sintering to produce ultrafine and highly homogeneous LDS microstructures that are unattainable through traditional melting routes. The review also identifies the emerging role of near-net-shape casting and additive manufacturing as transformative technologies capable of overcoming longstanding challenges related to defects, compositional inhomogeneity, and geometric limitations. Overall, the review emphasizes that optimized processing strategies and parameter control will be crucial to enhance efficiency, unlocking superior mechanical properties and realizing the full lightweight potential of LDS in advanced engineering applications.

With the development of wearable exoskeletons, people's demand for wearable exoskeletons is no longer limited to functionality alone. The aesthetics and symbolic meanings of wearable exoskeletons have also become a focus of attention. This paper aims to propose a method for designing the form of active wearable upper-limb exoskeletons based on product semantics, in order to enhance their form design to meet workshop scenarios and satisfy the physical and mental needs of users. Firstly, it analyzes product symbols and uncovers the appearance semantics, function semantics, symbolic semantics, and market semantics of wearable exoskeletons based on the product semantics. Then, the design process for the form design of active wearable upper-limb exoskeletons based on product semantics is proposed. Finally, design verification is implemented through design proposals of active wearable upper-limb exoskeletons used in logistics handling, fully considering the intrinsic connection between exoskeletons and their product semantics without interfering with the key technical structure of the exoskeleton and effectively integrating refined product semantic symbols into design practice. This can improve the functional utility of exoskeletons, enhance user experience, endow them with rich sociocultural and emotional connotations, and increase market competitiveness.

Hierarchical honeycombs are particularly useful in aerospace industries because of their capability to overcome challenges related to bend-dominated behaviour. These structures are ideal for aeronautical applications because of their capacity to integrate lightweight design, good mechanical properties, and efficient load distribution. However, the efficacy under applied loads is influenced by the type of polygon cell typically introduced to the parent hollow structure. The current literature has gaps in knowledge regarding the highest order of hierarchy that can practically be achieved for hierarchical honeycombs with different cell shapes at the vertices or for the walls. This review paper documents work carried out on hierarchical honeycombs to examine their mechanical behaviour and how they can be efficiently designed. The first section of the paper highlights the deformation behaviour of hierarchical honeycombs in use today. The next section contains a discussion on the constraints in determining the order of hierarchy attainable for hierarchical honeycombs, particularly the geometric parameters. This is followed by a review of relevant applications for hierarchically built honeycomb parts in aerospace industries. The efficacy, as well as challenges related to using additive manufacturing in building hierarchical honeycombs, are then highlighted. Alternatives for future studies and advances in hierarchical honeycombs applied in the aerospace sector are addressed in the last section of the paper.

To improve the anti-corrosion and waterproof performance of marine vessel surfaces, many acrylic resin coating materials have been proposed, but many of them still have the problem of low anti-corrosion performance. To address this problem, nanocomposites based on modified multi-walled carbon nanotubes are proposed in the study with a view to improving the anticorrosive properties of acrylic resin coating materials. The study first examined the structure of the nanocomposite using relevant instruments. The results showed that the nanocomposite was able to mix SiO2, multi-walled carbon nanotubes, and 1H,1H,2H,2H-perfluorodecyltrimethoxysilane efficiently with good waterproofing and anticorrosion properties. Subsequently, the nanocomposites were applied to acrylic resin coating materials for experiments. The outcomes revealed that the coating material had a contact angle of 131.8° and an average impact strength of 58.3 kg·cm. The impedance value was much higher than 109 Ω·cm2 after immersion in 3.5 wt% NaCl solution for 8 days, and the impedance value was stable. The above results indicate that the nanocomposites based on modified multi-walled carbon nanotubes proposed in the study can improve the anticorrosive properties of acrylic resin coating materials. This study provides a scientific basis for improving the anticorrosion performance of marine vessel surfaces.

During the laser welding process of aluminum alloy, the high reflectivity of aluminum alloy to laser and the severe fluctuation of the keyhole lead to highly unstable energy absorption, which readily induces defects such as spatter and porosity. Furthermore, the multi-physical field coupled dynamic behaviors within the molten pool, involving heat transfer, fluid flow, phase transformation, and element evaporation, are difficult to capture and quantify, resulting in a lack of precise theoretical guidance for this process. To address these issues, a multiple-reflection laser absorption model for the keyhole in the aluminum alloy laser welding molten pool was established. Basic assumptions were applied to the laser welding process to simplify the calculation of the molten pool mathematical model. The governing equations for the laser welding molten pool were established. Finally, the laser welding molten pool process was simulated. Experimental results demonstrate that employing a laser incident angle of 30° reduces the molten pool flow velocity by approximately 40%, effectively suppressing the spatter phenomenon. When the welding speed is increased to 8.0 m/min, the escape efficiency of molten pool bubbles is enhanced by 50%, and the uniformity of element diffusion is significantly improved. The comprehensive optimization of parameters can improve weld formation quality by more than 35%. The study provides an effective numerical analysis tool for understanding keyhole dynamics and molten pool behavior in aluminum alloy laser welding, significantly enhancing the comprehension of defect formation mechanisms. The established models and optimization results can offer a theoretical basis and parameter design guidance for the development of high-quality and high-efficiency aluminum alloy laser welding processes.

This review provides a comprehensive analysis of interfacial reactions and the impact of surface metallization in high-temperature die-attach, which is critical for ensuring the reliability of interconnects and joints in power electronic module packaging and integration. With the emergence of high-temperature filler materials, distinctive features in interfacial interactions and microstructural evolution arise, necessitating detailed examination to select suitable surface finishes based on the filler metals and specific applications. Metallization does not always enhance joint quality and reliability, so cost-effectiveness and manufacturability must also be considered when metallization is deemed viable. The formation of intermetallic compounds (IMCs) during interfacial reactions is particularly important, although solid solution formation at interfaces also warrants attention. This review evaluates five commonly used high-temperature metal solder fillers—high-Pb solder, Au-based solder, Bi-Ag solder, Zn-Al solder, and nano Ag paste—focusing on their interactions with various metallized surfaces in die-attach bonding. The effects of metallization on interfacial reactions and bond formation are discussed, leading to recommendations for cost-effective and reliable metallizations suitable for these applications.

The mechanical behaviour and bio-corrosion properties of Zn-1.2Cu-xMn (x = 0.2, 0.4, and 0.6 wt%) alloys was investigated in this study. The alloy compositions were produced via liquid metallurgical processing and characterized using scanning electron microscopy (SEM), and X-ray diffractometry (XRD). The mechanical properties were evaluated using hardness, tensile properties, fracture toughness measurement while corrosion studies in Hank's solution was used to access the bio-corrosion behaviour. The results show that the tensile test of the studied Zn alloys increased in ultimate strength from 79.52 to 112.65 MPa, fracture toughness from 6.99 to 7.71 MPam1/2 and hardness from 10.59 to 18.80 Hv, but with significant reduction in ductility from 5.21% to 3.63%. The improved mechanical properties were attributed to solid solution and second phase strengthening. The alloys presented appropriate in vitro degradation rates of 25–73 µm/year in Hank's solution. Based on the results demonstrated by the studied Zn-Cu-Mn alloys with suitable mechanical properties and ideal degradation behavior, it is projected as a promising candidate for cardiovascular stent applications.

For processing the difficult-to-cut materials, TiAlSiN coatings have been widely applied to machining tools. Pulse magnetic field treatment, as a novel, fast, and environmentally friendly post-treatment method, can directly modify the finished TiAlSiN-coated tools without causing physical damage. This study investigates the wear resistance of pulse magnetic field-treated TiAlSiN-coated carbide samples under both dry and lubricated friction conditions. Results show that pulse magnetic field-treated TiAlSiN-coated samples exhibit improved wear resistance and friction reduction in both friction environments. In dry friction conditions, the coating's coefficient of friction decreased by 13.73%, resulting in a more stable friction process. In lubricated conditions, the coefficient of friction decreased by 23.46%. Due to the effects of the pulse magnetic field, the hardness of the coating and substrate increased by 6.58% and 3.7%, respectively. The bonding phase Co in the carbide substrate exhibited phase transformation and increased defect density, such as dislocations. These changes enhanced the bonding strength at the coating/substrate interface, thereby improving its mechanical performance and tribological behavior.