Papers by Keyword: Damping Material

Abstract: In blast field test, strong mechanical shock and vibration affect the output of blast pressure sensors. To avoid this phenomenon, a pressure sensor vibration reduction installation structure was designed for the measurements of ground reflection pressure. The damping material was used in the installation structure. And certain blast field test had been carried out. The data from the field blast test was compared to transducers with vibration reduction and transducers without vibration reduction. The results show that the obvious effect of the vibration reduction can eliminate vibration interference. And it is suitable for the measurements of shock wave over-pressure in blast field test.

Abstract: A novel vibration damping structure is designed based on the existing package structure of MEMS vector hydrophone. It is desirable that this novel structure can isolate the vibration noise caused by working platform so as to improve the anti-noise ability of hydrophone. This novel structure is made of “dow corning” damping silicone rubber which is manufactured with a certain proportion because of its small Young’s Modulus. The hydrophone is fabricated in the form of original packaging structure firstly and then in vibration-isolation packaging structure. Laboratory tests by means of the shaking table test and standing-wave tube test are performed to validate the theoretical results. The test results prove that the vibration damping structure can effectively isolate the interference signal produced by working platform without affecting the sensitivity of hydrophone obviously.

Abstract: The dynamic response of a floating structure subjected to underwater explosion is greatly complicated by the explosion of a high explosive, propagation of shock wave, complex fluid–structure interaction phenomena, and the dynamic behavior of the floating structures. A numerical investigation has been carried out to examine the behavior of stiffened steel plates subjected to shock loads resulting from an Underwater Explosion (UNDEX). The aim of this work is to obtain the optimal configuration to resist underwater shock loading. A non-linear dynamic numerical analysis of the underwater explosion phenomena associated with different geometrical stiffened steel plates is performed using the ABAQUS/Explicit finite element program. Special emphasis is focused on the evolution of mid-point displacements. Further investigations have been performed to study the effect of including material damping and the rate-dependant material properties at different shock loads. The results indicate that stiffener configurations and shock loads affect greatly the overall performance of steel plates and sensitive to the material data.

Abstract: The paper mainly concerns about how relative density and pre-compression quantity of metal rubber shock absorber (MRSA) affect acceleration transmissibility, natural frequency and other parameters of MRSA. In order to study the influence law, sine wave sweep experiment was conducted on different MRSA, and the final data was processed. The influence law could provide reference for practical application of MRSA.

Abstract: Metal rubber material is a mesh structure woven by wire (metal rubber called MR), a new type of isolated-vibrated material with elastic rubber property ^{[1, 2]}. Static mechanical properties of MR are discussed in this paper. First of all, this paper introduces load-displacement function of micro element spring. And a constitutive model of MR is proposed. Secondly, this paper discusses how different parameters such as wire diameter and relative density influence energy dissipation. Also, compared the theoretical results with the experimental results in order to test the accuracy of the theory.

Abstract: Predicting the dynamic response of a floating and submerged structure subjected to underwater explosion is greatly complicated by the explosion of a high explosive, propagation of shock wave, bubble-pulse, complex fluid-structure interaction phenomena and the dynamic behavior of the floating structures. A numerical simulation has been carried out to examine the behavior of elliptical submersible pressure hull to non-contact underwater explosion (UNDEX) and take the effect of bubble-pulse. The finite element package ABAQUS was used to model the UNDEX and the fluid-structure interaction (FSI) phenomena. The pressure wave resulting from an UNDEX was assumed to be a spherical wave. Plastic strain and the time histories of the wet-surface displacement, velocity and von Mises stress are presented. The analytical results are valuable for designing underwater vehicles to resist UNDEX.

Abstract: Acceleration signals at the mounts of an excavator cab are collected and analyzed, on the basis of which causes of peak values in the sound pressure level (SPL) at the drivers right ear (DRE) are discussed. A damping material layer made up of chlorobutyl rubber is arranged to the cabs panels by simulations according to results of panel acoustical contribution analysis, which indicates a great decline of the SPL peak values.

Abstract: A theoretical study on damping properties of multi-layered hybrid materials was presented with the aim to obtain good damping materials with a broad and high damping range. The value of the multi-layered organic hybrid materials consisting of polarized polymers and small molecules was evaluated via the correspondence principle. Similarly, the damping properties of the multi-layered organic hybrid materials were predicted according to our previous work. With increasing the number of the layers of multi-layered hybrids, the temperature dependence of could be improved and it was almost rectangular transition range with values for the area under the linear curve. Therefore, it could be considered to be a new approach to improve the temperature dependence of the damping materials and obtain good damping materials with a broad and high damping range.

Abstract: In the emulsion system, styrene, acrylate monomers and montmorillonite (Mt) were used to prepare interpenetrating polymer network/montmorillonite (IPN/Mt) nano-composite. X-ray diffraction (XRD), transmission electron microscopy (TEM) and dynamic mechanical analysis (DMA) were used to characterize the structure and damping property of the new material. Results of XRD and TEM showed that the layer structure of Mt was destroyed and Mt dispersed in the polymer matrix by single layer. The result of DMA indicated that the damping property of Styrene-Acrylic IPN/Mt was much better than that of Styrene-Acrylic IPN. Damping value of the Styrene-Acrylic IPN/Mt was well improved and the maximum of tanδ increased from 0.621 to 0.739, with a broad damping domain ranging from -41°C to 140+°C. All these findings indicated that styrene-acrylate IPN /Mt nano-composite of broad damping temperature range and high damping value was successfully prepared.

Abstract: The hydrogen-induced internal friction and mechanical strength of the Ti-rich Ti34Zr11Cu47Ni8 and (Ti34Zr11Cu47Ni8)98Si2 hydrogenated glassy alloys have been investigated. It is found that the tensile strength is more than 0.8 GPa at room temperature when the hydrogen content is below about 20 at% for both alloys. The frequency dependence of peak temperature of the hydrogen-induced internal friction of (Ti34Zr11Cu47Ni8)98Si2-17.3 at%H hydrogenated glassy alloys has been clarified. Activation energy and pre-exponential factor are estimated to be 0.35 eV and 1.3x10-12, respectively. Compared with these values with those of Zr40Cu49Al10Si1 hydrogenated glassy alloys which show an internal friction peak around 300 K at about 300 Hz, it is found that the activation energy is much smaller than that of the latter although the pre-exponential factor is almost the same. Considering their similar composition and different component (Al), it is suggested that the component Al of the latter glassy alloys is effective for the higher activation energy which results in the increase of the peak temperature.