Search Results (252)

This study presents the development and performance evaluation of a rock asphalt-modified damping asphalt binder tailored for interlayer applications in photovoltaic pavement systems. A series of composite binders was formulated by incorporating Qingchuan rock asphalt, crumb rubber powder, and SBS polymer into base asphalt using an orthogonal design approach. The effects of different modifiers and their interactions were systematically assessed through conventional physical tests, DSR, BBR and damping ratio measurements. Furthermore, full-scale specimens (30 cm × 30 cm) were subjected to both single-pass and 24 h sustained loading tests to simulate real-world stress conditions. The results revealed that rock asphalt (RA) significantly enhanced the high-temperature stiffness and rutting resistance, while SBS improved ductility and low-temperature flexibility. Rubber powder (RP) notably increased the damping ratio, demonstrating superior energy dissipation potential. Among the nine formulations, the ternary blend of SBS, RA, and RP (denoted as L5) exhibited the most balanced and optimal performance, with G*/sinδ exceeding 5.0 kPa at 64 °C, a ductility of 132 cm, and damping ratios above 0.14. Load testing confirmed the material’s capacity for both instantaneous deformation resistance and delayed elastic recovery. These findings suggest that the L5 formulation is well suited for use in smart pavements where both mechanical durability and vibration attenuation are required. Full article

Fiber-reinforced composite materials exhibit orthotropic behavior, characterized by complex orthotropic engineering constants such as Young’s modulus, Poisson’s ratio, and shear modulus. It is widely recognized that basalt fibers possess superior resistance to elevated temperatures compared to glass fibers. However, the behavior of these fibers within composites at typical operational temperatures for automotive and consumer goods applications has not been thoroughly investigated. A novel measurement setup based on the non-destructive impulse excitation method has been developed for the automated identification of complex orthotropic engineering constants as a function of temperature. This study provides a comparative analysis of the identified engineering constants of bidirectionally fabric-reinforced glass and basalt composites with an epoxy matrix, across a temperature range from −20 °C to 60 °C. The results reveal only minimal differences in stiffness and damping behavior between the examined glass and basalt samples. Full article

Concrete structures increasingly face dynamic loading conditions, such as seismic events, vehicular traffic, and environmental vibrations, necessitating enhanced energy dissipation capabilities. The damping ratio, a critical parameter quantifying a material’s ability to dissipate vibrational energy, is typically low in conventional concrete, prompting extensive research into strategies for improvement. This review comprehensively explores the impact of advanced concrete types—such as Engineered Cementitious Composites (ECCs), Ultra-High-Performance Concrete (UHPC), High-Performance Concrete (HPC), and polymer concrete—on enhancing the damping behavior. Additionally, key mix design innovations, including fiber reinforcement, rubber powder incorporation, and aggregate modification, are evaluated for their roles in increasing energy dissipation. External factors, particularly curing conditions, are also discussed for their influence on the damping performance. The findings consolidate experimental and theoretical insights into how material composition, mix design, and external treatments interact to optimize dynamic resilience. To guide future research, this paper identifies critical gaps including the need for multi-scale numerical simulation frameworks, standardized damping test protocols, and long-term performance evaluation under realistic service conditions. Advancing work in material innovation, optimized mix design, and controlled curing environments will be essential for developing next-generation concretes with superior vibration control, durability, and sustainability. These insights provide a strategic foundation for applications in seismic-prone and vibration-sensitive infrastructure. Full article

In engineering structures, damping materials are an effective way to improve vibration characteristics, but they can significantly increase the weight and cost of the structure. In this study, based on the variable density topology optimization algorithm, combined with finite element simulation and experimental validation, the vibration damping performance of a composite structure with steel plate and damping material is optimized. With the objective of minimizing the resonance response and the constraint of damping material volume, the material distribution of the damping layer is optimized, and the amount of damping material used is successfully reduced by 31.2%. By building a test rig and comparing the vibration responses under the three working conditions of no damping, full damping coverage, and optimized damping, the effectiveness of the optimization strategy is verified, and a significant reduction in vibration response is achieved. This study provides an innovative solution for lightweight design and cost control in engineering. Full article

Medical phantoms are essential to imaging calibration, clinician training, and the validation of therapeutic procedures. However, most ultrasound phantoms prioritize acoustic realism while neglecting the viscoelastic and anisotropic properties of fibrous soft tissues. This gap limits their effectiveness in modeling realistic biomechanical behavior, especially in wave-based diagnostics and therapeutic ultrasound. Current materials like gelatine and agarose fall short in reproducing the complex interplay between the solid and fluid components found in biological tissues. To address this, we developed a soft, anisotropic composite whose dynamic mechanical properties resemble fibrous biological tissues such as skin and skeletal muscle. This material enables wave propagation and vibration studies in controllably anisotropic media, which are rare and highly valuable. We demonstrate the tunability of damping and stiffness aligned with fiber orientation, providing a versatile platform for modeling soft-tissue dynamics and validating biomechanical simulations. The phantoms achieved Young’s moduli of 7.16–11.04 MPa for skin and 0.494–1.743 MPa for muscles, shear wave speeds of 1.51–5.93 m/s, longitudinal wave speeds of 1086–1127 m/s, and sound absorption coefficients of 0.13–0.76 dB/cm/MHz, with storage, loss, and complex moduli reaching 1.035–6.652 kPa, 0.1831–0.8546 kPa, and 2.138–10.82 kPa. These values reveal anisotropic response patterns analogous to native tissues. This novel natural fibrous composite system affords sustainable, low-cost ultrasound phantoms that support both mechanical fidelity and acoustic realism. Our approach offers a route to next-gen tissue-mimicking phantoms for elastography, wave propagation studies, and dynamic calibration across diverse clinical and research applications. Full article

Magnetorheological (MR) foams represent a class of smart materials with unique tunable viscoelastic properties when subjected to external magnetic fields. Combining porous structures with embedded magnetic particles, these materials address challenges such as leakage and sedimentation, typically encountered in conventional MR fluids while offering advantages like lightweight design, acoustic absorption, high energy harvesting capability, and tailored mechanical responses. Despite their potential, challenges such as non-uniform particle dispersion, limited durability under cyclic loads, and suboptimal magneto-mechanical coupling continue to hinder their broader adoption. This review systematically addresses these issues by evaluating the synthesis methods (ex situ vs. in situ), microstructural design strategies, and the role of magnetic particle alignment under varying curing conditions. Special attention is given to the influence of material composition—including matrix types, magnetic fillers, and additives—on the mechanical and magnetorheological behaviors. While the primary focus of this review is on MR foams, relevant studies on MR elastomers, which share fundamental principles, are also considered to provide a broader context. Recent advancements are also discussed, including the growing use of artificial intelligence (AI) to predict the rheological and magneto-mechanical behavior of MR materials, model complex device responses, and optimize material composition and processing conditions. AI applications in MR systems range from estimating shear stress, viscosity, and storage/loss moduli to analyzing nonlinear hysteresis, magnetostriction, and mixed-mode loading behavior. These data-driven approaches offer powerful new capabilities for material design and performance optimization, helping overcome long-standing limitations in conventional modeling techniques. Despite significant progress in MR foams, several challenges remain to be addressed, including achieving uniform particle dispersion, enhancing viscoelastic performance (storage modulus and MR effect), and improving durability under cyclic loading. Addressing these issues is essential for unlocking the full potential of MR foams in demanding applications where consistent performance, mechanical reliability, and long-term stability are crucial for safety, effectiveness, and operational longevity. By bridging experimental methods, theoretical modeling, and AI-driven design, this work identifies pathways toward enhancing the functionality and reliability of MR foams for applications in vibration damping, energy harvesting, biomedical devices, and soft robotics. Full article

Traditional magnetorheological elastomers (MREs) often suffer from limited modulus tunability and insufficient energy dissipation, which restrict their applications. This study prepared a novel composite material by an MR gel (MRG) embedded within the MRE, called the MRE encapsulating MRG, to synergistically enhance these properties. Annular and radial MRE encapsulating MRG configurations were fabricated using 3D-printed molds, and their dynamic mechanical performance was characterized under varying magnetic fields (0–1 T) via a rheometer. The results revealed that the composite materials demonstrated significantly improved magnetic-induced modulus and magnetorheological (MR) effects compared to conventional MREs. Specifically, the annular MRE encapsulating MRG exhibited a 238.47% increase in the MR effect and a 51.35% enhancement in the magnetic-induced modulus compared to traditional MREs. Correspondingly, the radial configuration showed respective improvements of 168.19% and 27.03%. Furthermore, both the annular and radial composites displayed superior energy dissipation capabilities, with loss factors 2.68 and 2.03 times greater than those of pure MREs, respectively. Dynamic response tests indicated that composite materials, particularly the annular MRE encapsulating MRG, achieve faster response times. These advancements highlight the composite’s potential for high-precision damping systems, vibration isolation, and adaptive control applications. Full article

The pressing issue of global warming has prompted industries to seek sustainable and renewable materials that can reduce the use of petroleum-based products. Natural fibers, as bio-based and environmentally friendly materials, offer a promising solution. In this study, ramie fiber, which is one of the strongest natural fibers, is used as reinforcement, and the mechanical properties of natural rubber composites are evaluated. The composites were fabricated using a vulcanizing technique at 150 °C, and the fibers were cut into different lengths (5 mm, 10 m, and 15 mm) and weights (15 g, 30 g, and 60 g). Mechanical performance tests, including tensile and tear strength and hardness, were conducted. The results showed that as fiber concentration increased, so did the curing time. Moreover, the composites with higher fiber concentration had higher strength. The composite with a 10 mm fiber length and 60 g weight showed the highest tensile strength (10.35 MPa). Maximum tear strength (52.51 kN/m) was achieved with 5 mm fiber length and 60 g weight. Hardness values reached up to 88 Shore A (10 mm fiber length and 60 g weight), indicating excellent wear resistance. The specimen with the highest tensile strength was subjected to scanning electron microscope analysis. The SEM analysis revealed that the composite had a ductile type of fracture with appreciable plastic deformation, confirming good fiber–matrix interaction. These findings underscore the potential of ramie fiber–reinforced natural rubber composites as sustainable, high-performance alternatives to petroleum-based materials in structural and vibration-damping applications. Full article

Concerning building acoustics, the impact of sound propagation in the building structure can be considered one of the most relevant problems. Floating floors are an efficient solution, composed of a rigid walking surface above a resilient material. Functioning as a spring, the resilient layer must have adequate damping properties and compressive strength against permanent and imposed loads to guarantee its performance over time. In this context, this study aims to completely evaluate the impact sound reduction of composite lightweight floating floors formed by ceramic tiles and recycled rubber mats when subjected to prolonged loads, from material characterization to their application in a hypothetical scenario. This study was based on the dynamic stiffness (ISO 9052-1) and compressive creep (ISO 16534) of the resilient layer and the physical characterization of the ceramic tiles, predicting the present and future (15 years) impact sound reductions and their application in a hypothetical room, considering direct and indirect transmissions paths (ISO 12354-2). The results showed that the lightweight floating floor compositions lost their damping capability to a degree that can reduce their weighted reduction in the impact sound pressure level by up to 2 dB over prolonged periods (15 years). Howsoever, the compositions had considerable initial impact sound insulation capability and adequate performance maintenance over time. Full article

Composite sandwich structures play a significant role in various engineering applications due to their excellent strength-to-weight ratio, durability, fatigue life, acoustic performance, damping characteristics, stealth performance, and energy absorption capabilities. The optimization of these structures results in enhancing their mechanical performance, weight reduction, cost-effectiveness, and sustainability. This review provides a comprehensive analysis of recent advancements in the optimization techniques applied in the case of composite sandwich structures, focusing on structural configuration, facesheets, and innovative cores design, loading conditions, analysis methodologies, and practical applications. Various optimization procedures, single- and multi-objective algorithms, Genetic Algorithms (GAs), Particle Swarm Optimization (PSO), and Machine Learning (ML)-based optimization frameworks, as well as Finite Element (FE)-based numerical simulations, are discussed in detail. It highlights the role of core material and geometry, face sheet material selection, and manufacturing limitations in achieving optimal performance under static, dynamic, thermal, and impact loads under various boundary conditions. Furthermore, challenges such as computational efficiency, experimental validation, and trade-offs between structural weight and performance are examined. The findings of this review offer insights into the recent and future research directions of optimizing sandwich constructions, emphasizing the integration of advanced numerical techniques for analysis and efficient structural optimization. Full article

This study explores the vibrational behavior of Thermoformed Magneto-Piezoelectrets (TMPs), multifunctional materials consisting of thermoformed piezoelectrets with open tubular channels integrated with an additional magnetic layer. The inverse piezoelectric effect was characterized using laser vibrometry analysis, measuring the mechanical response of TMPs subjected to electrical excitation over a frequency range of 0–20 kHz. Vibrational analysis was conducted at 144 spatial points, enabling the construction of detailed three-dimensional (3D) maps of the vibration operational modes and the spatial distribution of the piezoelectric coefficient ($d_{33}$). The results demonstrated significant frequency-dependent behavior, with open channels exhibiting pronounced resonance peaks, whereas valleys displayed smoother and more uniform responses due to enhanced damping effects. The observed heterogeneity in vibrational behavior is attributed to structural variations, material composition, and anisotropic coupling between the piezoelectric and magnetic properties. The findings presented in this research provide a comprehensive understanding of the development and utilization of TMPs, offering parameters for enhancing their application and supporting new discoveries in studies related to the fabrication of novel thermoformed piezoelectric sensors. Full article

Enhancing the damping capacity of concrete structures is crucial for improving their resilience under dynamic loading conditions such as earthquakes, vehicular impacts, and industrial vibrations. This study presents a comprehensive review of how material properties—specifically fiber reinforcement, ductility, and toughness—affect the damping behavior of concrete. Various types of fiber reinforcements, including steel, polypropylene, and glass fibers, are analyzed in terms of their contribution to energy dissipation mechanisms such as crack bridging, fiber pullout, and frictional sliding. The role of the ductility index and toughness in augmenting the damping ratio is also discussed, demonstrating that higher ductility and toughness directly correlate with enhanced energy dissipation. Furthermore, the interrelationships between material properties and structural performance under cyclic loading are critically evaluated. The findings highlight that optimizing fiber content and improving the mechanical properties of concrete can significantly increase its damping capacity, thereby offering strategic pathways for designing safer and more durable infrastructure, especially in seismic-prone regions. This review aims to consolidate the current understanding and provide recommendations for future research focused on developing high-damping concrete composites. Full article

Both synthetic and natural rubber-like elastomers are widely employed in industrial applications (such as tires, seals, protective gloves, and damping absorbers) as well as in the food and animal husbandry industries. These materials should be regularly checked for contamination and the associated infectious risk since they frequently come into contact with food, animals, and people. Additionally, they could act as vehicle of microbes and, as a result, diseases. This pilot study investigates the antibacterial efficacy of novel elastomer formulations against Salmonella enterica subsp. enterica serovar Enteritidis and Legionella pneumophila, with possible applications in drinking water distribution systems (DWDSs). This study aims to evaluate the antimicrobial activity of two rubber and five silicone patented elastomers with antibacterial additives. Two microbiological concentrations (10³ and 10⁴ CFU/mL) were used to compare the efficacy of the elastomers. The results showed a significant decrease in bacterial load in several silicone formulations, with two of them showing the strongest bactericidal efficacy against L. pneumophila (0% and 3% survival rates for VMQ105 and VMQ500L formulations, respectively), despite the wide variations in S. Enteritidis inhibition. One rubber elastomer performed better than the other in terms of reducing bacterial survival for both pathogens (NBRCA) while NBROM showed a 0% survival rate only for L. pneumophila. The findings suggest that certain elastomer compositions might lessen the potential infectious risks in water systems or contaminated matrices. Future research may investigate in situ applications, particularly in hospitals or dental offices where these pathogens pose major health risks. Full article

The behavior of structural elements, which is very important in structural engineering, can be determined non-destructively using ambient vibration tests. Composite elements used in structures can be formed by combining elements of different materials. It is much more difficult to predict the structural behavior of composite elements because they are made of different materials. Ambient vibration tests are one of the most important methods used to determine the dynamic characteristics of composite elements. In this study, composite cantilever beams were formed by combining wood and steel profiles in various combinations. The dynamic characteristics of these beams (natural frequency, mode shape, modal damping ratio) were determined by both the numerical method and operational modal analysis (OMA) method. Firstly, the initial analytical models of the beams were modeled using the finite element program. The natural frequencies and mode shapes of the models were determined using the modal analysis method. While creating the initial analytical model, the material properties of the beams were entered by taking into account the standard values in the literature. Then, the dynamic characteristics of the beams were determined using an experimental modal analysis method (operational modal analysis test). The dynamic characteristics obtained from tests and the analysis of the initial analytical models were compared. The analytical models were calibrated according to the test results. In this way, the modeled beams were provided with a more realistic dynamic behavior. Numerical models were modeled using the SAP2000 program. As a result of the analysis, the dynamic characteristics and structural properties of composite cantilever beams were compared. As the elasticity modules and cross-sections of the profiles used in the beams increase, the stiffness of the beams also increases. It was determined that the natural frequencies of the composite beams increase with the increase in their stiffness. When the frequencies of the first modes of the least rigid wood (W) beam and the most rigid steel–wood–steel (S-W-S) beam were compared, an increase of 47% was detected. Full article

This study investigates the fatigue durability of Plexus MA300 methacrylic adhesive, which is employed in structural joints of metals, plastics, and composites. Cast adhesive specimens were subjected to cyclic tensile loads at a frequency of 5 Hz with a stress ratio R = 0.1. Six load levels were tested. Hysteresis loops were recorded during testing and analyzed in detail. Significant differences in fatigue fracture characteristics were observed depending on load level. Specimens subjected to high loads exhibited a characteristic radial structure with a distinct crack initiation point, whereas specimens tested at lower loads showed more uniform, matte fracture surfaces. Hysteresis loop analysis revealed phenomena typical for polymers: creep and damping causing energy dissipation. Various fatigue approaches were compared: stress-based, strain-based, energy-based, and stiffness-based. The highest coefficient of determination (R²) was obtained for the model based on strain energy density, indicating its superior utility in predicting the fatigue life of the tested adhesive. The obtained results contribute to the understanding of the fatigue behavior of methacrylic adhesives and provide practical data for structural joint design involving this material class. Full article