Lightweight Properties Research Articles

MECHANICAL AND MICROSTRUCTURAL BEHAVIOR OF ZE41 MAGNESIUM ALLOY REINFORCED WITH INCONEL FOR HIGH-PERFORMANCE APPLICATIONS

Abstract Magnesium alloys are known for their lightweight and desirable properties, as they hold significant potential for innovative engineering applications. The present study investigated the mechanical and microstructural characteristics of a magnesium alloy (ZE41) reinforced with Inconel ceramic particulates. The Magnesium Metal Matrix Composites (MMMC) were fabricated using the stir casting method, with varying weight percentages (wt. %) of Inconel (0, 2, 4, 6, 8, 10, 12 wt. %). The microstructural examinations of the MMMC specimens were performed using SEM, SEM+EDS analyses, and Optical Microscopy (OM), which revealed a strong interfacial bond well-defined between the Magnesium matrix and the Inconel particulates. This uniform distribution of reinforcement particulates significantly enhanced the mechanical properties of the composite materials. The tensile tests showed that the Ultimate Tensile Strength (UTS) improved progressively with up to 8% Inconel reinforcement, achieving a maximum UTS of 202.56 MPa, a 24.47% improvement compared to the base Magnesium alloy. However, the UTS decreased beyond 8% Inconel due to increased brittleness. Hardness tests indicated that the highest hardness value of 76.1 HV was achieved for the composite containing 12 wt.% Inconel, marking an 18.85% increase over the base alloy. Additionally, the wear rate decreased with increasing Inconel reinforcement, demonstrating improved wear resistance. Specifically, the wear rate dropped from 2.58 × 10-7 g/mm at 0% Inconel to 0.84 × 10-7 g/mm at 12% Inconel, showing a 67.44% reduction in wear rate compared to the pure AA6082 matrix. The findings from the present work, indicate the potential of Inconel-reinforced ZE41 composites towards achieving optimized strength and hardness levels for applications requiring high-performance materials. The present research is a contribution to the body of knowledge on the development of magnesium composites and highlights the importance of reinforcement compositions for enhancing their mechanical and microstructural characteristics.

Dynamic analysis of porous fiber‐reinforced sandwich composite panel with variable angle

AbstractDamped sandwich composite structures are increasingly used in the aerospace, automotive and energy sectors due to their high damping and lightweight properties. Here, a novel porous fiber‐reinforced sandwich composite structure is proposed, by punching holes in fiber cloth with impregnated damping solution, and resin flows through the holes during the formation of the composite structure, connecting the upper and lower prepreg layers. This paper focuses on the theoretical study of the free vibration behavior of simply supported composite porous multilayer fiber‐reinforced sandwich composite structures with arbitrary delamination angles. The vibrational differential equation including the orientation angle was established and solved using Rayleigh‐Ritz method and Navier method. Subsequently, the Abaqus finite element method and modal test analysis were used to evaluate the dynamic performance of the structure with different orientation angles, verify the proposed theoretical model and solution strategy, and perform structural optimization based on a genetic algorithm. The results show that the panel with the area ratio of the damping layer of 94.854% and a fiber orientation angle of multiples of 45° has excellent dynamic performance. This model has significant advantages in improving structural stiffness and provides a theoretical basis for practical engineering applications.Highlights A dynamic model of porous multilayer damping plate is established. The effect of different fiber orientation angle on porous plate is studied. An experimental platform is constructed to corroborate the theoretical accuracy. Structural optimization of porous plate is conducted using a genetic algorithm. The influence of structural parameters on the porous plate is analyzed.

Experimental and numerical analysis of pGFRP and wood cross-arm in latticed tower: a comprehensive study of mechanical deformation and flexural creep

The adoption of pultruded glass fibre-reinforced polymer (pGFRP) composites as a substitute for traditional wooden cross-arms in high transmission towers represents a relatively novel approach. These materials were selected for their high strength-to-weight ratio and lightweight properties. Despite various studies focusing on structures improvement, there still have a significant gap in understanding the deformation characteristics of full-scale cross-arms under actual operational loads. Existing study often concentrate on small coupon scale and laboratory condition, leaving a gap in understanding how the cross-arm behavior in full-scale acting on actual weather condition. This study aims to investigate the load-deflection and long-term creep behavior of a pGFRP cross-arm installed in a 132 kV transmission tower. The pGFRP cross-arm was load-tested on a customized rig in an open environment. Using the cantilever beam concept, deflection was analyzed and compared to wood cross-arms. Finite element analysis validated results, and long-term deformation under high-stress loads was assessed. The pGFRP cross-arms showed lower deflection at working loads compared to Balau wood, due to the latter’s higher elastic modulus and flexibility specifically at Point Y3, the critical issues necessitated reinforcement strategies. pGFRP cross-arms withstood higher bending stress, showing 32% less deflection under normal conditions and 15% less under broken wire conditions than Balau wood. Additionally, the creep strength of wood was 34% lower than that of pGFRP cross-arms. Besides that, the pGFRP cross-arm have highest elastic modulus than Balau-wood, shows that the composite cross-arm have better structural strength, resisting deformation and higher flexibility materials. Finite element analysis (FEA) confirmed these results with the relative error between them less than 1%. Consequently, the investigation into pGFRP cross-arm deformation behavior in this paper serves as a foundational framework for future research endeavors specifically for high transmission tower and other structural application.

Preparation and Application of Nature-inspired High-performance Mechanical Materials.

Natural materials are valued for their lightweight properties, high strength, impact resistance, and fracture toughness, often outperforming human-made materials. This paper reviews recent research on biomimetic composites, focusing on how composition, microstructure, and interfacial characteristics affect mechanical properties like strength, stiffness, and toughness. It explores biological structures such as mollusk shells, bones, and insect exoskeletons that inspire lightweight designs, including honeycomb structures for weight reduction and impact resistance. The paper also discusses the flexibility and durability of fibrous materials like arachnid proteins and evaluates traditional and modern fabrication techniques, including machine learning. The development of superior, multifunctional, and eco-friendly materials will benefit transportation, mechanical engineering, architecture, and biomedicine, promoting sustainable materials science. STATEMENT OF SIGNIFICANCE: Natural materials excel in strength, lightweight, impact resistance, and fracture toughness. This review focuses on biomimetic composites inspired by nature, examining how composition, microstructure, and interfacial characteristics affect mechanical properties like strength, stiffness, and toughness. It analyzes biological structures such as shells, bones, and exoskeletons, emphasizing honeycomb strength and lightness. The review also explores the flexibility and durability of fibrous materials like arachnid proteins and discusses fabrication techniques for biomaterials. It highlights impact-resistant materials that combine soft and hard components for enhanced strength and toughness, as well as lightweight, wear-resistant biomimetic materials that respond uniquely to cyclic stress. The article aims to advance sustainable materials science by exploring innovations in multifunctional and eco-friendly materials for various applications.

Timber Bridges in Modern Japan

In Japan, timber has been used for not only traditional building but also bridge construction since olden times. At least until the 1950s, various types of bridge were in service, including trestle, truss, suspension, etc. for forest railways. However such timber bridges were replaced with concrete or steel bridges, which were thought to be, and were called, “permanent bridges” in those days. Government policy represented by the Five-Year Plan for Road Construction in 1954 facilitated the replacements, and a large percentage of timber bridges disappeared from Japan. Since the late 1980s, new types of timber bridge, so-called “modern timber bridges”, began to be constructed in Japan. The development of materials such as glulam (glue-laminated timber) with a large section, curved glulam, etc. treated with preservative made it possible to construct roadway bridges with several ten-metre spans. The longest span bridge in Japan is Karikobozu Bridge, which was completed in 2003 and has three king post truss spans (the longest span being 48 m). Construction of modern timber bridges reached its peak around 2000 and decreased significantly after that. As budget allocations for public works projects were decreasing, it became difficult to construct symbolic timber road bridges with higher costs. From the 2010s onwards, new approaches have been tried for timber bridges, utilizing the lightweight properties and easy workability of timber but avoiding high-specification road bridge requiring higher costs. Typical examples are illustrated and recent directions discussed.

Study on strength properties of lightweight foamed composite with 0.6% volume fraction treated kenaf fibre

The Lightweight Foamed Composite (LFC) exhibits inherent limitations in mechanical strength due to its porous structure, hindering its wider application. This study presents a novel approach to enhancing LFC's mechanical strength properties by incorporating Treated Kenaf Fibre (TKF), a domestically available high-yield crop in Malaysia, offering a green and effective solution for “Sustainable Composite Reinforcement.” To optimize fibre incorporation, raw kenaf fibres were pre-treated with a 1.5 M NaOH solution for 12 hours. Subsequently, a 0.6% TKF by Volume Fraction (Vf) was integrated into the LFC mix. The fresh and hardened density of Treated Kenaf Fibre Lightweight Foamed Composite (TKFLFC) was controlled within 1200 ± 5% kg/m3. Next, the mechanical properties evaluation of TKFLFC involved compressive, flexural, and splitting tensile strength tests. By the 28-day mark, the compressive strength of LFC-TKF 0.6 showed a moderate improvement of 4%, while the flexural and splitting tensile strengths significantly increased by 56% and 62%, respectively, compared to LFC-Control. A performance index evaluation emphasizes the contribution of TKF in enhancing LFC's mechanical strength at the same densities. These findings demonstrate the potential for utilizing TKF in LFC as a green, sustainable civil construction material, offering valuable insights and opportunities for innovation.

Innovative modular systems for high-rise buildings

This paper presents the advancements in modular construction, highlighting steel and concrete modular systems, alongside an innovative lightweight and long span steel-concrete composite approach. It emphasizes the constructability, strength, and robustness of these systems, with steel modular systems leveraging lightweight properties for swift assembly and structural integrity through corner support systems, while concrete modular systems prioritize durability and fire resistance employing composite structural wall systems. The proposed lightweight steel-concrete composite system integrates the benefits of both materials, offering extended spans, durability, flexibility, and ease of assembly. Robust fast joining techniques coupled with lightweight steel fibre-reinforced slim floor system ensure expedited installation and global stability. The integration of automation and prefabrication techniques revolutionizes construction practices, enhancing productivity, efficiency, and quality. Additionally, this paper suggests further research directions to develop even more efficient, sustainable building solutions, unlocking new possibilities for the construction industry to improve productivity and resolve site installation challenges.

Experimental investigation, modeling and optimization of wire EDM process parameters for machining AA2024-B4C self-lubricating composite

Abstract Metal matrix composites (MMCs) are increasingly used across various manufacturing sectors, including automotive, defense, and aerospace, due to their exceptional strength-to-weight ratio, lightweight properties, high strength, and appreciable hardness when combined with suitable reinforcing materials. MMCs reinforced with carbide particles not only enhance the mechanical properties, but also exhibit self-lubricating characteristics, providing exceptional wear resistance. The self-lubricating properties of MMCs contribute significantly to minimizing the maintenance requirements, reducing operational costs, and advancing sustainability goals, rendering them indispensable for sectors such as aerospace, automotive, medical equipment, and energy. The present work addresses the challenges associated with machining advanced composite materials and proposes optimal machining parameters to overcome these difficulties. Here in the current investigation, aluminium alloy (AA2024) + 10 wt% B4C composite was selected as the workpiece material, and it was machined using a wire electric discharge machine. Response surface methodology was employed to develop predictive models for the output responses, namely surface roughness (R a ) and material removal rate (MRR). The accuracy of the predictive models was found to be 98.78% for R a and 93.54% for MRR, demonstrating their reliability. To optimize the machining performance, both single-objective and multi-objective optimization approaches were used. Taguchi’s signal-to-noise (S/N) ratio analysis was applied for single-objective optimization, while Pareto optimal fronts generated using the genetic algorithm facilitated the multi-objective optimization to maximize MRR and minimize R a effectively.

Advancements and Challenges of Lithium Battery Technology in Electric Aircraft

The demand for sustainable energy solutions has heightened the focus on electric aircraft as an effective approach to reduce reliance on fossil fuels and mitigate environmental issues like global warming. Among various battery technologies, lithium-ion batteries (LIBs) have emerged as a key contender for powering electric aircraft due to their high energy density, lightweight properties, and superior electrochemical performance. Lithium's low electrochemical potential and high electropositivity allow these batteries to deliver greater voltage, energy density, and charge/discharge efficiency compared to traditional lead-acid and nickel-metal hydride batteries. Additionally, LIBs exhibit fast charging, low self-discharge rates, and long operational lifespans, making them ideal for use in electric vehicles and other high-performance applications. However, the challenges of battery safety, energy density limitations, and environmental concerns regarding their production and recycling must be addressed to unlock their full potential in aviation. Continued advancements in these areas are crucial to achieving sustainable, high-performance electric aircraft.

Research Progress of Silicon/Carbon Anodes in Lithium-Ion Batteries

Lithium-ion batteries (LIBs) have garnered attention because of their high energy density and lightweight properties. However, LIBs typically use graphite for the anode material, which shows a relatively low specific capacity that can hardly meet the growing energy storage demands. Compared with traditional graphite anodes, silicon anodes have already been proven to possess higher specific capacities. Additionally, silicon is abundant and relatively inexpensive. Nonetheless, silicon anodes undergo significant volume expansion during the charge-discharge process, generating mechanical stress that can lead to potential cracking and capacity loss. Moreover, they exhibit relatively low initial coulombic efficiency, causing a considerable amount of lithium to be irreversibly consumed during the initial cycles. To address these issues, various nanotechnology-based strategies have been developed, including silicon/carbon (Si/C) composite anodes and the development of other nanostructured materials. These approaches aim to optimize interface structure, particle structure, and composite structure design to enhance battery performance and durability. This paper provides a comprehensive review of the application of nanotechnology in silicon anodes, focusing on the advancements in silicon/carbon composites and their effects on mitigating volume expansion, improving initial coulombic efficiency, and maintaining capacity retention. Additionally, it analyzes the impact of different nanostructure designs on battery performance.

A comparative study on mechanical properties of PLA, PETG, and carbon fiber prepared by fused deposition modeling

3D printing technology is a highly promising fast prototyping method. It is a technology that is rapidly being utilized for mass customization and manufacture of open-source designs in industries such as agriculture, healthcare, automobile, locomotive, aviation, and others. FDM is an additive manufacturing (AM) technology that creates a 3D physical object directly from a computer-assisted design (CAD) model by layering the feedstock, which is polymer filament material ejected through a nozzle. The test samples were made using Olivetti S2 3D printer and according to standard testing sizes like ASTM D638, ASTM D790, and ASTM D256. Mechanical properties: Three distinct materials, polylactic acid (PLA), carbon fiber-reinforced PLA, and carbon fiber-reinforced polyethylene terephthalate glycol (PETG) are evaluated through tensile test, flexural test, and impact test by varying the process parameters such as feed rate and infill pattern. PLA is a popular biodegradable biopolymer known for its high biocompatibility and sustainability. PETG material is a kind of chemical utilized in a variety of industrial processes due to its great durability, impact strength, and outstanding formability. It is preferred over various filaments because of its superior layer adherence and odorlessness. Carbon fiber-reinforced filament enhances structural components by providing high modulus, good surface finish, dimensional stability, and lightweight properties. This study revealed that at lower print speeds tensile strength in PLA has increased, especially with line infill parallel to the load. Conversely, at higher speeds weakened PETG-CF with triangular infill. PLA also showed superior flexural properties at lower speeds with line infill.

Preparation and Performance Study of Novel Foam Vegetation Concrete.

Vegetation concrete is one of the most widely used substrates in ecological slope protection, but its practical application often limits the growth and nutrient uptake of plant roots due to consolidation problems, which affects the effectiveness of slope protection. This paper proposed the use of a plant protein foaming agent as a porous modifier to create a porous, lightweight treatment for vegetation concrete. Physical performance tests, direct shear tests, plant growth tests, and scanning electron microscopy experiments were conducted to compare and analyze the physical, mechanical, microscopic characteristics, and phyto-capabilities of differently treated vegetation concrete. The results showed that the higher the foam content, the more significant the porous and lightweight properties of the vegetation concrete. When the foam volume was 50%, the porosity increased by 106.05% compared to the untreated sample, while the volume weight decreased by 20.53%. The shear strength, cohesion, and internal friction angle of vegetation concrete all showed a decreasing trend with increasing foaming agent content. Festuca arundinacea grew best under the 30% foaming agent treatment, with germinative energy, germinative percentage, plant height, root length, and underground biomass increasing by 6.31%, 13.22%, 8.57%, 18.71%, and 34.62%, respectively, compared to the untreated sample. The scanning electron microscope observation showed that the pore structure of vegetation concrete was optimized after foam incorporation. Adding plant protein foaming agents to modify the pore structure of vegetation concrete is appropriate, with an optimal foam volume ratio of 20-30%. This study provides new insights and references for slope ecological restoration engineering.

Boosting High Electric Breakdown Strength for Excellent Energy Storage Performance in Bi0.5Na0.5TiO3-Based Lead-Free Ceramics via a High Entropy Strategy.

High-performance dielectric capacitors featuring large recoverable energy storage density (Wrec) and high discharge efficiency (η) are beneficial to realize the device miniaturization, lightweight property, and sustainability of advanced pulse power systems. The obtainment of a high electric breakdown strength (Eb) is crucial for improving the energy storage performance of dielectric materials. However, as for Bi0.5Na0.5TiO3 (BNT) lead-free relaxor ferroelectric ceramics, the relatively lower Eb directly limits their electrical performance improvement and practical applications. Herein, a popular high entropy strategy was employed to rationally design and prepare the (Bi0.5Na0.5)x(Sr0.25Ba0.25La0.25K0.25)(1-x)TiO3 (BNSLBKT-x) lead-free relaxor ferroelectric ceramics based on the BNT matrix. Encouragingly, the BNSLBKT-0.2 high-entropy ceramic exhibits a high Eb of 510 kV/cm, and this can be ascribed to the refined grains and enhanced activation energy. Moreover, it is confirmed that the polar nanoregions (PNRs) exist in the BNSLBKT-0.2 ceramic by the piezoresponse force microscopy (PFM) and transmission electron microscopy (TEM) characteristics, further strengthening relaxation behaviors and decreasing remanent polarization (Pr). It is anticipated that a high Wrec of 4.6 J/cm3 and a good η of 86% are obtained in this BNSLBKT-0.2 high-entropy ceramic. More importantly, the BNSLBKT-0.2 ceramic displays excellent frequency stability of capacitive energy storage at 10-1000 Hz and good temperature stability at 20-140 °C. The fast discharge rate (τ0.9 = 0.26 μs) and the high PD of 49.2 MW/cm are also achieved in this BNSLBKT-0.2 ceramic. The findings demonstrate that this high entropy design is an effective strategy for developing dielectrics with excellent energy storage capability to meet the requirements of modern dielectric capacitor applications.

On secondary recycling of high-density polyethylene with reinforcement of stubble powder by a material extrusion process for construction applications

In the past two decades, several studies have been reported using agricultural waste as reinforcement in thermoplastic matrices for lightweight and tunable mechanical properties. However, the recycling of thermoplastic with reinforcement of agricultural waste has constraints in the form of the volume of recycled material to support the concept of a circular economy. One of the solutions for bulk consumption of such agricultural and thermoplastic waste is its use in construction applications. In the present study, high-density polyethylene (HDPE) was secondary (2°) recycled by reinforcement of stubble waste powder (SWP) through the material extrusion (MEX) process for possible applications in the construction industry. The melt flow index (MFI) investigation suggested the maximum loading of 15% SWP with the recycled HDPE matrix in the present case study. Further, the filament was prepared by using the design of experiment (DoE) with input parameters (heat treatment (pre-heat treatment (PreHT) and post-heat treatment (PostHT), barrel temperature (170–180°C) and screw speed (3–5 RPM) on single screw extruder). The results suggest that the combination of PreHT, 170°C-barrel temperature and 4 RPM screws speed resulted in a maximum Young’s modulus (E) of 1386.57 MPa. The PreHT has promoted the recrystallization of the HDPE-SWP blend, which has significantly increased E. The differential scanning calorimetry (DSC) reveals that the HDPE-SWP composite was more thermally stable after each thermal cycle. In addition, the results of this study were also supported and correlated with the observation of scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), thermogravimetric analysis (TGA), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), surface profiling and 3D printability with MEX.

High-Cycle Fatigue Behaviour and Structural Robustness of Glass Fibre-Reinforced Polymer Tiled Web-Core Sandwich Panel Unit Cells in Load-Bearing Structures

This paper explores the fatigue behaviour and robustness of tiled web-core sandwich panels used in glass fibre-reinforced polymer bridges, which are increasingly favoured for their lightweight and corrosion-resistant properties. Fatigue tests are conducted on unit cell specimens with manually induced crack initiation, simulating accidental damage scenarios in glass fibre-reinforced polymer bridge components. The objective is to assess the integrity of individual unit cells when subjected to a localized force at the top flange after damage initiation. The fatigue tests reveal three phases in the behaviour of a tiled unit cell. Initially, there is a substantial rapid stiffness degradation with crazing crack appearance within the cross-section. Subsequently, a plateau phase occurs, with limited stiffness degradation and stable crazing cracks, the duration of which depends on the applied fatigue load. Lastly, rapid stiffness degradation with substantial crack growth leads to ultimate failure within roughly a thousand cycles. Further analysis using digital image correlation reveals strain concentrations at the location of crazing cracks and crack propagation occurring interlaminarly but not through the plies of the top and bottom flanges, ensuring a robust design. This research enhances the understanding of the tiled sandwich panels, offering prospects for resilient load-bearing structures in glass fibre-reinforced polymer bridges and structural engineering applications.

An investigation of recycled rubber composites reinforced with micro glass bubbles: an experimental and numerical approach

ABSTRACT Recycled rubber is widely used for its lightweight and cost-effective properties but often has limited mechanical strength, restricting its applications. This study enhances the mechanical performance of devulcanised recycled rubber by reinforcing it with micro glass bubbles (GBs) featuring a density of 0.65 g/cm³ and an elastic modulus of 3.5 GPa, offering a high strength-to-density ratio. Uniaxial compression tests were conducted on samples with GB volume fractions of 5%, 10%, and 15%. Results were validated through finite element analysis (FEA) in ABAQUS/Standard, incorporating randomised GB distributions. A 2D representative volume element (RVE) with randomly distributed GBs was modelled, applying periodic boundary conditions to simplify the composite into an equivalent homogeneous material. Numerical simulations assessed the effects of GB diameters (30, 40, and 50 µm) and inclusion size ranges (20–50 µm and 10–60 µm), finding minimal impact on results. The RVE, sized at 238 µm, accurately represented macroscale composite behaviour. Stress-strain behaviour was analysed using average stress and strain tensors. The strong agreement between experimental and numerical results validates the proposed method, demonstrating its accuracy in predicting the mechanical behaviour of the reinforced composite material.

Integration of PVA Solar Cells in Automobiles: An Eco-Friendly Energy Alternative

This research paper describes the use of polyvinyl alcohol (PVA) solar cells in the automobile industry as a renewable energy solution. PVA solar cells have become more popular because of its lightweight and flexible properties, and can be easily integrated into vehicle surfaces to utilize solar energy. PVA solar cell technology gives numerous benefits to the user, including reduced reliance on fossil fuels, enhanced energy efficiency, and lower carbon emissions. The paper gives insights of the mechanisms of energy generation through these coatings, the environmental advantages of using biodegradable materials, and the potential for improved vehicle performance. Paper also addresses the challenges of durability, efficiency, and market acceptance. Eventually, the integration of PVA solar cells represents a promising step towards a more sustainable and eco-friendly automotive industry.

Mechanical Analysis of Different Composites Used in Automotive Chassis Design

Background: In the rapidly changing automobile sector, the necessity for lightweight yet durable chassis materials is essential. The incorporation of composite materials offers the benefit of decreasing the total weight of vehicles while preserving adequate load-bearing capacity. This research examines three materials: ASTM A148 Gr 80-50 steel, P100/6061 aluminum alloy, and Graphite Al GA 7–230 Metal Matrix Composite (MMC). These materials were chosen for their ability to improve vehicle performance by optimizing strength, flexibility, and impact resistance. Methods: The chosen materials underwent stringent mechanical testing to evaluate their appropriateness for chassis applications. The evaluated key mechanical parameters comprised tensile strength, flexural strength, elongation, and percentage area reduction. Tensile and flexural tests were conducted to assess the materials capacity to endure various stress types, while elongation and area reduction measurements offered insights into their ductility and deformation properties under load. Results: ASTM A148 Gr 80-50 Steel demonstrated significant load-bearing capacity, featuring a tensile strength of 390 MPa and a flexural strength of 810 MPa. It exhibited commendable ductility, with 22% elongation and a 35% reduction in cross-sectional area, signifying its appropriateness for heavy-duty chassis applications. P100/6061 Aluminum alloy provides a balance of strength and weight, featuring a tensile strength of 320 MPa and a flexural strength of 640 MPa. It exhibited improved ductility with 30% elongation and a 41% reduction in area, rendering it suitable for applications where weight sensitivity is paramount. Despite possessing inferior tensile (76.9 MPa) and flexural strengths (159 MPa), graphite aluminum GA 7–230 MMC demonstrated superior ductility with 51% elongation and 68% area reduction. These characteristics demonstrate superior energy absorption during deformation, rendering it appropriate for impact-resistant applications. Conclusion: This study emphasizes the unique benefits of each material for car chassis applications. ASTM A148 Gr 80-50 steel has shown to be a viable option for severe load-bearing applications owing to its superior strength and commendable ductility. The P100/6061 aluminum alloy demonstrated efficacy as a lightweight chassis design choice, achieving a balance between structural integrity and weight reduction. Graphite Al GA 7-230 MMC, albeit exhibiting reduced strength, showcased enhanced energy absorption properties, rendering it appropriate for applications necessitating impact resistance. Future study may investigate the application of hybrid composites or the further optimization of these materials to improve vehicle performance while reducing weight. Major Findings: The study compared three materials- ASTM A148 Gr 80–50 steel, P100/6061 aluminum alloy, and Graphite Al GA 7–230 MMC- for automotive chassis applications through rigorous mechanical testing. ASTM A148 Gr 80–50 exhibited superior strength and ductility, making it ideal for load-bearing applications. P100/6061 demonstrated a balance of strength and lightweight properties, suitable for weight-sensitive designs. Graphite Al GA 7–230 MMC showcased exceptional ductility and energy absorption, favoring impact-resistant applications. These findings underscore the materials' diverse advantages in enhancing chassis performance.

Design and characteristics of a double-layer gradient grid structure for broadband electromagnetic wave absorption

Grid structures are renowned for their lightweight and high-strength properties. When combined with wave absorption technology, they can form multifunctional broadband wave-absorbing structures. However, traditional grid wave-absorbing structures face challenges in impedance matching control, limiting their effectiveness over a broader frequency band. Additionally, conventional simulation optimization methods in the field of wave-absorbing structures are inefficient and yield suboptimal results. To address these issues, this study introduces a double-layer gradient grid absorber composite structure (DGGS) and employs a genetic algorithm optimization framework to adjust its structural parameters. By applying the principles of impedance matching and genetic optimization algorithms, the DGGS successfully reduces electromagnetic wave reflectivity, achieving significant absorption effects within the 2.45 to 18 GHz frequency range. Furthermore, the absorber is constructed from composite materials such as fiberglass, ensuring reliable strength and significant cost-effectiveness. The genetic algorithm has optimized the structural parameters to achieve the optimal impedance gradient and maximize absorption efficiency. This structure not only exhibits exceptional mechanical strength but also demonstrates excellent energy absorption performance, presenting broad application prospects.

Safety-enhanced control for a MuscleDrive waist-assistive exoskeleton

This study introduces the MuscleDrive Powered Waist-Assistive Exoskeleton (PWE), which is specifically designed with comprehensive safety features in both its hardware and software components. The hardware of the MuscleDrive PWE incorporates fluidic muscle actuators (FMAs) to improve mechanical compliance, taking advantage of their lightweight and elastic properties. The software component features an innovative control system that utilizes the PSTC-RLESO controller. This controller ensures precise and reliable torque trajectory tracking during normal operation and facilitates smooth, safe recovery from significant torque errors during abnormal interactions. Using the Lyapunov stability theorem, this study demonstrates that the closed-loop states of the MuscleDrive PWE with PSTC-RLESO are globally uniformly ultimately bounded (UUB). Experimental comparisons between PSTC-RLESO and a PID controller show that PSTC-RLESO significantly enhances safety during MuscleDrive PWE operation while maintaining efficient tracking performance. In the experiments, safety performance is assessed through damping injection by PSTC-RLESO. Additionally, tests conducted on seven healthy subjects indicate that the MuscleDrive PWE provides adequate torque assistance and ensures user safety, as evidenced by surface electromyography (sEMG) da ta and questionnaire responses.