Search Results (11)

To fulfill the vibration damping requirements of plate structures under complex conditions, additional damping structures with entangled metallic wire material (EMWM) are proposed based on the excellent physical properties of EMWM. A batch of specimens with different filament diameters, densities, and thicknesses are prepared. The stiffness and loss factors are taken as the evaluation indexes, and orthogonal tests are conducted to obtain the tensile, shear, and compression properties. The results show that the optimal parameter combinations can be obtained through orthogonal tests. For the specimens with optimal parameter combinations, the mechanical tests under different loading rates and loading displacements are carried out. With the increase in loading rate, the tensile and shear forces appear to display fracture failure in advance, and the compression performance is stable without significant changes. The change rule under each mechanical test is explored using the stiffness and loss factor evaluation index. It provides a reference for the analysis of the preparation parameters of subsequent additional damping structures with EMWM. Full article

Entangled metallic wire material (EMWM) can be utilized as a novel elastic element in vibration isolation devices for mechanical actuators. This paper presents a vibration experiment aimed at investigating the degradation behavior of mechanical performance in EMWM under a cyclic compressive environment. An electric vibration testing system, coupled with an isolation structure, is employed to apply compressive loads to the EMWM specimens. Through visual observations and quasi-static compression tests, the variations in geometric morphology and mechanical properties are studied, considering different relative densities and vibrational stress amplitudes. The results indicate a significant reduction in the compressed dimension of the specimens as the number of cycles increases, without any wire fractures or wear. The mechanical properties exhibit an increasing secant modulus and a decreasing loss factor. These variations ultimately lead to a gradual deviation of the vibration characteristics of the isolation structure from its design state, including resonance frequency and transmission rate. To forecast the mechanical property degradation of EMWM, prediction models are proposed, incorporating its dimensions, modulus, and damping by fitting the experiment results. This research provides valuable experimental data and presents an effective method to determine the operational lifespan of vibration isolators utilizing EMWM. Full article

In this paper, the response characteristics of wave propagation in entangled metallic wire materials (EMWMs) are investigated by acoustic emission. The frequency, amplitude of wave emission, and the pre-compression force of the specimen can be adjusted in the experimental setup. EMWM specimens fabricated from stainless steel wires and with different design parameters are tested in this work. The results show that waves of different amplitudes propagate in EMWMs with approximate linear characteristics and the fluctuation coefficient of wave passing ratios is calculated below 15%. The response spectrum of passing waves shows a distinct single-peak characteristic, with the peak response at approximately 14 kHz. The parameters of pre-compression force, porosity, wire diameter, helix diameter, specimen height, and the layered structure of specimens have no significant effect on the frequency characteristics but moderately affect the wave passing ratios. Notably, EMWMs exhibit a lower wave passing ratio (ranging from 0.01 to 0.18) compared to aluminum alloy and natural rubber. The characteristics of response spectrums can be successfully reproduced by the finite element simulation. This work demonstrates EMWMs’ potential as an acoustic frequency vibration isolation material, offering excellent performance and engineering design convenience. Full article

Nanocomposite materials have recently attracted great attention for their wide range of applications, such as in smart materials, flexible electronics, and deformation sensing applications. Such materials make it possible to combine a polymer with functional fillers. In this study, flexible artificial leathers, exhibiting insulating properties and containing 1.5 or 2wt.% of graphene oxide (GO) in the polyurethane (PU) layer, were electrically activated via CO₂ laser irradiation to obtain conductive paths at the surface exposed to the laser beam. As the material retained its insulating properties out of the irradiation areas, the laser scribing method allowed, at least in principle, a printed circuit to be easily and quickly fabricated. Combining a variety of investigation methods, including scanning electron microscopy (SEM), optical profilometry, IR and Raman spectroscopies, and direct current (DC) and alternate current (AC) electrical measurements, the effects of the laser irradiation were investigated, and the so-obtained electrical properties of laser-activated GO/PU regions were elucidated to unveil their potential use in both static and dynamic mechanical conditions. In more detail, it was shown that under appropriate CO₂ laser irradiation, GO sheets into the GO/PU layer were locally photoreduced to form reduced-GO (RGO) sheets. It was verified that the RGO sheets were entangled, forming an accumulation path on the surface directly exposed to the laser beam. As the laser process was performed along regular paths, these RGO sheets formed electrically conductive wires, which exhibited piezoresistive properties when exposed to mechanical deformations. It was also verified that such piezoresistive paths showed good reproducibility when subjected to small flexural stresses during cyclic testing conditions. In brief, laser-activated GO/PU artificial leathers may represent a new generation of metal-free materials for electrical transport applications of low-current signals and embedded deformation sensors. Full article

Particular attention has been given to the complexity of the elastic-porous sandwich structure with entangled metallic wire mesh (EMWM), which is a novel rigid-flexible heterogeneous and symmetrical material. The orthogonal experiment design for vacuum brazing was adopted for sensitivity analysis of the key fabrication process on the performances of an EMWM sandwich structure. The shear behaviors of the sandwich structures with different vacuum brazing parameters (e.g., heating rate, brazing temperature, and holding time) were analyzed by mechanical experiments and an interfacial microstructure. The results indicated that the failure behavior of the sandwich structure could be divided into four stages in the mode-I experiment. In addition, the joint quality of the different vacuum brazing process could be shown by the mode-II experiment, and the failure behaviors involves three stages. Additionally, the failure behaviors of the sandwich structure were mainly associated with the deformation of the EMWM core and the strength of the brazing joint. In addition, the relationship between the joint strength and the shear performance of the sandwich structure was revealed through the interfacial microstructure. Furthermore, the importance of the optimized vacuum brazing parameters to fabricate the novel sandwich structure with the best joint performance was demonstrated in this work. Full article

To reduce the transmission of vibration energy from the ship’s pipeline to the bulkhead, a novel all-metal pipe element passing through the bulkhead with symmetrical elastic installation was proposed in this paper. A metal bellow, a multi-layer thin-walled symmetrical structure, was used as an elastic element and entangled metallic wire materials (EMWM) were used as a damping element. The insertion loss was adopted to evaluate the vibration damping performance. The results show that compared with the pipe element passing through the bulkhead with rigid installation, the vibration damping performance of the pipe element passing through bulkhead with symmetrical elastic installation can significantly isolate the vibration transition, and the maximum average insertion loss in each direction can reach 25.4 dB. A thermal-vibration joint test system of the pipe element passing through the bulkhead was built. A series of comparison experiments were carried out to investigate the influence of temperature, symmetrical measure points, and exciting directions on the vibration response transmitted to the bulkhead. Therefore, the vibration damping performance was verified. Full article

To reduce the vibration of a ship’s high-temperature pipeline, a long coated damping structure (LCDS) with entangled metallic wire material (EMWM) is proposed in this paper. The structural analysis of the long coated damping structure for pipelines is carried out. The theoretical analysis indicates that increasing the thickness of the damping layer in a particular range can improve the vibration attenuation effect of an LCDS. Additionally, experimental verification confirms this analysis after an experimental system for pipelines. From the results, it is observed that increasing the thickness of the coated layer can effectively improve the damping property of LCDS to a certain extent. The change of the coated length and the temperature has little effect on the vibration attenuation effect of an LCDS, indicating that the LCDS can work well in a high-temperature environment. Full article

In this paper, a symmetrically coated damping structure for entangled metallic wire materials (EMWM) of pipelines was designed to reduce the vibration of high temperature (300 °C) pipeline. A series of energy dissipation tests were carried out on the symmetrically coated damping structure at 20–300 °C. Based on the energy dissipation test results, the hysteresis loop was drawn. The effects of temperature, vibration amplitude, frequency, and density of EMWM on the energy dissipation characteristics of coated damping structures were investigated. A nonlinear energy dissipation model of the symmetrically coated damping structure with temperature parameters was established through the accurate decomposition of the hysteresis loop. The parameters of the nonlinear model were identified by the least square method. The energy dissipation test results show that the symmetrically coated damping structure for EMWM of pipelines had excellent and stable damping properties, and the established model could well describe the changing law of the restoring force and displacement of the symmetrically coated damping structure with amplitude, frequency, density, and ambient temperature. It is possible to reduce the vibration of pipelines in a wider temperature range by replacing different metal wires. Full article

In this paper, the dynamic compressive mechanical properties of entangled metallic wire material (EMWM) under low-velocity impact were investigated and the constitutive model for EMWM under low-velocity impact was established. The research in this paper is based on a series of drop-hammer tests. The results show that the energy absorption rate of EMWM is in the range from 50% to 85%. Moreover, the EMWM with a higher relative density would not plastically deform macroscopically and has excellent characteristics of repetitive energy absorption. With the increase in relative density, the maximum deformation of EMWM decreases gradually, and the impact force of EMWM increases gradually. With the increase in impact-velocity, the phenomenon of stiffness softening before reaching the maximum deformation of EMWM becomes more significant. A constitutive model for EMWM based on the Sherwood–Frost model was established to predict the dynamic compressive mechanical properties of EMWM. The accuracy of the model was verified by comparing the calculated results with the experimental data of the EMWM with different relative densities under different impact-velocities. The comparison results show that the established model can properly predict the dynamic compressive mechanical characteristics of EMWM under low-velocity impact loading. Full article

In this paper, the stiffness and damping property of entangled metallic wire materials (EMWM) under quasi-static and low-velocity impact loading were investigated. The results reveal that the maximum deformation of the EMWM mainly depends on the maximum load it bears, and that air damping is the main way to dissipate impact energy. The EMWM can absorb more energy (energy absorption rate is over 60%) under impact conditions. The EMWM has excellent characteristics of repetitive energy absorption. Full article

Entangled metallic wire material (EMWM) is a kind of porous damping material. To promote the engineering application of EMWM, it is necessary to establish the constitutive model of EMWM to estimate its mechanical properties. In this paper, a series of quasi-static compression experiments for plate-like EMWM specimens made of austenitic stainless steel wire (06Cr19Ni10) with different densities were carried out in the temperature range of 20–500 °C. It was found that the stiffness of the plate-like EMWM would increase with the increases in the ambient temperature. The non-linear characteristics of the force–displacement curve of the plate-like EMWM would be weakened. Taking the spatial structural characteristics of the plate-like EMWM and the influence of the thermal expansion of the structure into account, a new constitutive model for plate-like EMWM was presented by the combination of the Johnson–Cook model and the Sherwood–Frost constitutive framework model. The accuracy of the model was verified by the experimental data under different temperatures. The results show that the calculated results of the model are consistent with the experimental results. This model can provide an effective theoretical basis for predicting the mechanical properties of plate-like EMWM and guiding its design. Full article