Excellent Damping Research Articles

Twinning damping interface design and synergistic internal friction behavior in FeMnCrCo high-entropy alloys

Vibration and noise reduction has always been important problem to be solved in the fields of rail transit, aerospace, marine engineering, and so on. In this paper, a novel Fe65-XMn20Cr15CoX (X = 5, 10, 15, 20) dual-phase high-entropy damping alloy with excellent properties were prepared by vacuum melting. The dependence of the alloy damping behavior on the twin interface, magnetic properties and phase interface was emphatically analysed. The effects of Co content on its microstructure, damping behavior and magnetic properties were investigated. The results show that with the increase of Co content, ε martensite gradually transforms to γ austenite, and the number of twins increases gradually. The peak damping (Q−1) increased from 0.0442 to 0.0595, an increase of 34.6%. The coupled effects of magneto-mechanical hysteresis, twin interface motion, and phase interface motion provide the alloy's excellent damping properties. The alloy has a higher damping internal friction peak of around 200 °C, which is due to the phase transition from ε to γ at the temperature. By adjusting the Co content, the phase content and twinning and other microstructures of the alloy can be regulated, and multiple damping mechanisms can be coupled to achieve higher damping performance.

Experimental investigation for novel hybrid journal bearing with hydrostatic squeeze film and metal mesh damper in series

PurposeThis study aims to present a novel hydrostatic squeeze film-metal mesh journal bearing (HS-MMJB), which uses both hydrostatic squeeze film damper (HSFD) and metal mesh damper (MMD), to suppress the vibration of rotor-bearing systems.Design/methodology/approachThe lubrication equations were introduced to calculate the dynamic characteristics of HS-MMJB, and the response analyses of rotor systems were carried out. Experiments were conducted to study the vibration reduction of a rotor system with HS-MMJB. In addition, experiments for different oil supply pressures in the HS-MMJB were conducted.FindingsThe theoretical and experimental results show that the HS-MMJB exhibits excellent damping and vibration attenuation characteristics. Moreover, the stability of the rotor system can be improved by controlling the oil supply pressure.Originality/valueThere is a dearth of research on vibration characteristics of rotor system support by journal bearing combining HSFD and MMD. Moreover, the active oil pressure control is implemented to improve the stability of rotor system.

Energy Dissipation and Performance Assessment of the Connected Structure with a One-Side Damping Layer

Due to aesthetic demands and the necessity for multi-functionality, a unique structure with one or multiple links connecting adjacent buildings has attracted the attention of researchers. In order to improve vibration control, this study investigates the seismic mitigation performance of a connected structure with a one-side damping layer. The simplified shear model is employed to derive the structure’s motion equation. Based on the Kanai-Tajimi filtered spectrum model, the seismic response variances are calculated using the Lyapunov equation. To investigate the seismic energy distribution and mitigation performance, three models of the connected structure with a damping layer are analyzed using the index of the mean kinetic energy. The results shows that the stiffness and damping coefficient affects the vibration energy, while the excessive stiffness of the damping layer is shown to be detrimental to the damping effects. In sum, the novel connected structure shows excellent damping ability and effectively reduces the vibration energy. Damping layers placed at a lower position with a stiffer structure are shown to enhance the damping effect and lead to more energy dissipation through the damping layer. Thus, this study concludes that the introduction of a One-Side damping layer into the connected structure is an excellent alternative strategy for adjusting the energy distribution of the connected structure and meeting the design requirements.

Stability of damping capacity and mechanical properties of high-Zn-concentration Al–Zn–Mg–Sc alloy

The microstructure, damping capacity, mechanical properties, and the performance stability of high-Zn-concentration Al–Zn–Mg–Sc alloys after annealing treatment were studied. The Al–20Zn–0.5 Mg–0.5Sc alloy contained fine grains, a high number of solution atoms, Zn phases, Al 3 Sc phases, and high-density fine η and η' phases. Decreasing the Zn content led to the disappearance of the Zn phases and the decrease of intragranular η phases density and solution atom number. Increasing the Mg content did not increase the number of solution atoms but increased the size of the intragranular η phases. The Al–20Zn–0.5 Mg–0.5Sc alloy exhibited higher internal friction value and higher strength than the other two alloys because of its satisfactory grain boundaries and Al/Zn interface sliding ability at high temperature, as well as its high solid solution and second phase strengthening effects at room temperature. All annealed Al–Zn–Mg–Sc alloys exhibited excellent damping capacity and mechanical properties stability during the DMA test at the highest temperature of 360 °C due to their high structural stability. • A novel Al alloy with excellent damping capacity, mechanical properties, and performances stability was obtained. • The satisfactory GB and Al/Zn interface sliding ability led to the Al–Zn–Mg–Sc alloy exhibited well damping capacity. • The high solid solution and second phase strengthening effects led to the Al–Zn–Mg–Sc alloy exhibited high strength. • Sc addition and annealing led to the Al–Zn–Mg–Sc alloy exhibited excellent structural and properties stabilit.

Characterization of (B4C+Ti) Hybrid Reinforced Mg and AZ91D Composites

Ceramic hybrid particulate reinforced magnesium matrix composites have attracted much attention in recent years, owing to their light weight, high specific strength and stiffness, excellent wear and damping properties, and have very wide popularization and application prospects in the automotive and aerospace fields. A simple and novel technique, in situ reactive infiltration technique, was utilized to prepare (B4C+Ti) hybrid reinforced Mg and AZ91D composites. The microstructure, produced phases, wear, compression and bending performance were characterized and analyzed in depth. The results showed that extending the holding time for preparing the composites and magnesium alloy as the matrix were both beneficial for the generation of interpenetrating networks within the composites, which means more sufficient and complete in situ reactions between B4C and Ti particles. More sufficient and complete reactions facilitate stronger interfacial bonding, leading to an improvement of the wear, compression and bending performance of the composites. The wear mechanisms for both kinds of composites were abrasive and delamination wear. (B4C+Ti)/AZ91D composites exhibit better compression performance and this can be attributed to the microstructure of the composites and work-hardening and softening during compression.

Investigation of buckling of laminated composites repaired by resin injection using acoustic emission and cohesive zone simulation method

Due to their low weight ratio, excellent damping behavior, and high strength characteristics, composite materials are widely used in different industries, including aerospace. Despite the excellent mechanical behavior, most of these materials suffer from damages such as delamination when undergoing low-energy impacts. In the present study, repairing the composite structures using the resin injection into the damaged zone is analyzed. In some samples, initial delamination is included during the manufacturing process using the Teflon film, while the other samples are left to be intact. Furthermore, the delamination inside the composite sample has been simulated using the cohesive zone method (CZM) using ABAQUS software. The samples with delamination were repaired with the resin injection method. Finally, all samples underwent the buckling test, and the buckling process of the samples was monitored using the acoustic emission method. The amounts of damage mechanisms of delamination growth, fiber breakage, and matrix cracking were calculated using the wavelet method. The results show a good agreement between the experimental results with both the finite element method (FEM) and the acoustic emission results. Besides, the restoration percentages of compressive strength in samples repaired with stacking sequence [0]8, [90]8, and [0/90]8 were 88%, 87%, and 91.7%, respectively.

Structure, Martensitic Transformation, and Damping Properties of Functionally Graded NiTi Shape Memory Alloys Fabricated by Laser Powder Bed Fusion.

Besides the unique shape memory effect and superelasticity, NiTi alloys also show excellent damping properties. However, the high damping effect is highly temperature-dependent, and only exists during cooling or heating over the temperature range where martensitic transformation occurs. As a result, expanding the temperature range of martensite transformation is an effective approach to widen the working temperature window with high damping performance. In this work, layer-structured functionally graded NiTi alloys were produced by laser powder bed fusion (L-PBF) alternating two or three sets of process parameters. The transformation behavior shows that austenite transforms gradually into martensite over a wide temperature range during cooling, and multiple transformation peaks are observed. A microstructure composed of alternating layers of B2/B19′ phases is obtained at room temperature. The functionally graded sample shows high damping performance over a wide temperature range of up to 70 K, which originates from the gradual formation of the martensite phase during cooling. This work proves the potential of L-PBF to create NiTi alloys with high damping properties over a wide temperature range for damping applications.

Surface integrity and accuracy based aspects in EDM of Cu-based SMA: an experimental investigation with microstructural analysis

ABSTRACT The need for innovative materials has increased in the current era of research and technology. Advanced materials such as shape memory alloys are in great supply in the industrial and commercial sectors. It is a unique and very uncommon metal alloy that can regain its original shape after being subjected to extremely low temperatures. SMAs may be classified as NiTi-based, Cu-based, or Fe-based depending on the metal-combination. Alloys based on copper have excellent elasticity and damping properties that allow them to withstand a broad variety of temperatures. Using the EDM method, this research investigates the effects of Ton, Toff, Ip, and GV on SR and dimensional deviation. 8.87 mm and 4.79 mm are the greatest and lowest values of SR that can be found, respectively. The dimensional deviation ranges from 0.03 mm to 0.28 mm, with a minimum value of 0.03 mm. Ton and Ip have a greater influence on surface roughness than Toff and GV. Images from SEM of workpiece samples show the production of micro-cracks as-well-as macro-ridges on the surface of the sample during EDM operations. SEM micrographs depicted the deviation in the dimensions of the workpiece samples after EDM operations on Cu-based SMA samples.

Bio-based polyurethane/hindered phenol AO-80 composites for room temperature high damping properties

Elastomeric damping materials are essential in modern life. Apart from natural rubber, conventional elastomers are mostly based on petroleum-based sources. Moreover, elastomers exhibit excellent damping properties in the glass transition region, the glass transition temperature (Tg) of elastomers is lower than room temperature, resulting in poor damping properties at room temperature. However, because of limited and unsustainable petrochemical resources and environmental pollution, sustainable development and green environmental protection have become important principles in the design of damping materials, and most damping materials are used at room temperature. Therefore, designing bio-based materials with high damping properties at room temperature to replace conventional cross-linked rubber materials is crucial. Herein, we prepared bio-based millable polyurethane (bio-MPU)/hindered phenol 3,9-bis-{1,1-dimethyl-2[β-(3-tert-butyl-4-hydroxy-5-methylphenyl-)propionyloxy]ethyl}-2,4,8,10-tetraoxaspiro (Wang et al., 2016; Wang et al., 2016) [5,5]-undecane (AO-80) composites to overcome the challenge of sustainable development and high damping properties at room temperature. Bio-MPU samples with high Tg were synthesized from bio-based modified polylactic acid-based polyols, 4, 4′-diphenylmethane diisocyanate, and unsaturated chain extender 3-allyloxy-1, 2-propanediol. AO-80 was mixed with bio-MPU to further increase the Tgand enhance the damping properties of the bio-MPU/AO-80 composites. The properties of the bio-MPUs and bio-MPU/AO-80 composites were systematically evaluated. This study proposes a strategy to design high damping properties from bio-based raw materials and reduce our dependence on fossil resources.

A High-Performance MEMS Accelerometer with an Improved TGV Process of Low Cost.

High-performance MEMS accelerometers usually use a pendulum structure with a larger mass. Although the performance of the device is guaranteed, the manufacturing cost is high. This paper proposes a method of fabricating high-performance MEMS accelerometers with a TGV process, which can reduce the manufacturing cost and ensure the low-noise characteristics of the device. The TGV processing relies on laser drilling, the metal filling in the hole is based on the casting mold and CMP, and the packaging adopts the three-layer anodic bonding process. Moreover, for the first time, the casting mold process is introduced to the preparation of MEMS devices. In terms of structural design, the stopper uses distributed comb electrodes for overload displacement suppression, and the gas released by the packaging method provides excellent mechanical damping characteristics. The prepared accelerometer has an anti-overload capability of 10,000 g, the noise density is less than 0.001°/√Hz, and it has ultra-high performance in tilt measurement.

Morphological Evolution and Damping Properties of Dynamically Vulcanized Butyl Rubber/Polypropylene Thermoplastic Elastomers.

We successfully prepared butyl rubber (IIR)/polypropylene (PP) thermoplastic vulcanizate (IIR/PP-TPV) for shock-absorption devices by dynamic vulcanization (DV) using octyl-phenolic resin as a vulcanizing agent and studied the morphological evolution and properties during DV. We found that the damping temperature region of the IIR/PP-TPV broadened with the disappearance of the glass transition temperature (Tg) in the PP phase, which is ascribed to the improvement of compatibility between the IIR and PP with increasing DV time. As DV progresses, the size of the dispersed IIR particles and the PP crystalline phase decreases, leading to the formation of a sea–island morphology. After four cycles of recycling, the retention rates of tensile strength and elongation at break of the IIR/PP-TPV reached 88% and 86%, respectively. The size of the IIR cross-linking particles in the IIR/PP-TPV becomes larger after melt recombination, and the continuous PP phase provides excellent recyclability. Significantly, the prepared IIR/PP-TPV exhibits excellent recyclability, high elasticity, and good damping property.

Enhancing damping capacity and mechanical properties of Al-Mg alloy by high strain rate hot rolling and subsequent cold rolling

The damping capacity of high Mg alloyed Al-Mg alloy (Al-9.2Mg-0.8Mn-0.2Zr-0.15Ti) prepared by high strain rate hot rolling (HSRR) and subsequent cold rolling (CR) are carefully studied. Both the strain amplitude dependent internal friction (ADIF) at room temperature and the temperature dependent internal friction (TDIF) at elevated temperature are detected by a dynamic mechanical analyzer (DMA). The results indicate that the subsequent cold rolling can significantly improve the damping capacity of the alloy. The as-CRed alloy exhibits higher strength and better damping capacity than the as-HSRRed alloy, with the ultimate tensile strength (UTS) of 606 ± 6 MPa, the elongation to rupture of 11.6 ± 0.6% and the Q-1 value of 0.019 at room temperature with the strain of 1 × 10-3 and the frequency of 1 Hz. The room temperature damping of the as-CRed alloy is mainly ascribed to the low stacking fault energy (SFE), the high dislocation density and the finer broken second phase particles. Moreover, the as-CRed alloy also presents excellent high temperature damping, with the maximum Q-1 value of 0.212 ± 0.003 at 361 ℃ with the frequency of 1 Hz. The relatively high damping capacity of the cold rolled sheet for a given frequency and temperature can be attributable to the special microstructure characteristics including the high dislocation density, the elongated lamellar grains with shear bands and the high fraction of LAGBs.

Bio-Based Polyurethane and Its Composites towards High Damping Properties.

The operation of mechanical equipment inevitably generates vibrations and noise, which are harmful to not only the human body but also to the equipment in use. Damping materials, which can convert mechanical energy into thermal energy, possess excellent damping properties in the glass transition region and can alleviate the problems caused by vibration and noise. However, these materials mainly rely on petroleum-based resources, and their glass transition temperatures (Tg) are lower than room temperature. Therefore, bio-based materials with high damping properties at room temperature must be designed for sustainable development. Herein, we demonstrate the fabrication of bio-based millable polyurethane (BMPU)/hindered phenol composites that could overcome the challenges of sustainable development and exhibit high damping properties at room temperature. BMPUs with a high Tg were prepared from modified poly (lactic acid)-based polyols, the unsaturated chain extender trimethylolpropane diallylether, and 4,4′-diphenylmethane diisocyanate, and 3,9-Bis-{1,1-dimethyl-2[β-(3-tert-butyl-4-hydroxy-5-methylphenyl-)propionyloxy]ethyl}-2,4,8,10-tetraoxaspiro [5,5]-undecane (AO-80) was added to prepare BMPU/AO-80 composites. Finally, the properties of the BMPUs and BMPU/AO-80 composites were systematically evaluated. After adding 30 phr of AO-80, the Tg and maximum loss factor (tan δmax) of BMPU/AO-80 composites increased from 7.8 °C to 13.5 °C and from 1.4 to 2.0, respectively. The tan δmax showed an improvement of 43%. Compared with other polyurethanes, the prepared BMPU/AO-80 composites exhibited higher damping properties at room temperature. This study proposes a new strategy to reduce society’s current dependence on fossil resources and design materials featuring high damping properties from sustainable raw materials.

Seismic performance of reinforced concrete frame with lead viscoelastic damper under mainshock-aftershock sequences

This study proposes a strategy of utilizing novel lead viscoelastic damper (LVD) to improve the seismic performance of the weakened reinforced concrete (RC) frame under mainshock-aftershock sequences. The working mechanism and mechanical behavior of the LVD were experimentally investigated through cyclic loading tests. A six-story LVD frame was designed to have similar structural characteristics to the original RC frame and modeled in OpenSees. Incremental dynamic analyses were carried out on both RC frame and LVD frame under mainshock only scenario and mainshock-aftershock sequences. The mainshock and aftershock seismic performance of the LVD frame and RC frame was assessed at various damage states. Results show that the developed LVD characterizes by high effective stiffness, excellent damping capacity, low-frequency sensitivity, and stable hysteretic performance. Although with weakened RC components, the LVD frame still has about 25.1% higher median PGA demands than the RC frame at various mainshock damage states, indicating that the LVD system plays a significant role in enhancing the mainshock seismic performance of the RC frame. The aftershock IDA results confirm that thanks to the excellent damping capacity of the LVD, the weaker RC frame with LVD systems outperforms the original RC frame by about 21.08%, 10.59%, and 13.33% in median aftershock PGA demands, aftershock collapse capacity, and residual aftershock collapse capacity, respectively.

Gecko-inspired adhesive structures enable efficiently thermal conductance and vibration dissipation in a highly mismatched system

There is often a trade-off between thermal conductance and vibration dissipation of polymer-based thermal interface materials (TIMs). Achieving efficient thermal management requires a sufficiently high filler content, however, which in turn raises the storage modulus of TIMs and thus compromises their damping performances. Inspired by Nature’s climbers of geckos, we envisage that the abundant short dangling ends of the comb-brush copolymers, like the gecko feet-hairs structures, could comfort to the highly mismatched interfaces between constituent materials (TIMs/substrate) and inside composites (polymer/fillers). Control experiments reveal that the short molecular hair structures are typically positively correlated with thermal boundary conductance of polymer-based TIM composites, which is contrary to the usual understanding in pure polydimethylsiloxane systems. Tailoring the weight ratio of comb-brush copolymers offers the optimal thermal conductivity (4.9 ± 0.1 W·m−1·K−1) and contact thermal resistance (0.2 ± 0.05 K·cm2·W−1). Additionally, the dissociation of van der Waals interaction between polymer/fillers and the broadened relaxation spectrum efficiently dissipate the vibration energy, endowing TIMs with excellent damping capacity over a broad frequency range (＞0.5 Hz). This study points out a promising direction for next-generation high-performance TIMs, powering the development of intelligent connected vehicles.

Enhanced damping and thermal conductivity of hBN/silicone rubber composites via strong interfacial action

High integration and miniaturization of electronic systems require thermal conductivity and mechanical damping materials. In this study, hexagonal boron nitride (hBN) particles were modified by vinyltrimethoxysilane (V171) and hexadecyltrimethoxysilane (N3116) for comparing, and described as V171-hBN and N3116-hBN, respectively. The pristine and surface modified hBN were filled in vinylmethylpolysiloxane (VMQ), and then vulcanized to fabricate hBN/silicone rubber composites. The damping properties of V171-hBN/silicone rubber composites were significantly higher than that of pristine hBN/silicone rubber composites, while N3116-hBN/silicone rubber composites were in contrast. The strong interfacial action in V171-hBN/silicone rubber composites came from the chemical bond by vinyl groups on the surface of V171-hBN taking part in the vulcanization of VMQ. This strong interfacial action led the deformation of hBN, and the internal friction between layers of hBN significantly increased to dissipate more energy. As a result, V171-hBN/silicone rubber composites with excellent damping and thermal conductivity as well as good mechanical properties were obtained.

Investigation on dynamic characteristics of composite sandwich plates with co-cured damping core

The purpose of this paper is to investigate how to improve the damping performance of carbon laminates when novel viscoelastic layer is inserted into the structure. Viscoelastic layer is a rubber polymer with excellent damping property. In this study, the novel rubber polymer is prepared by orthogonal test method and co-curing theory. A parameter analysis method based on finite element simulation is proposed to explain how to enhance the damping performance of carbon laminates by arranging viscoelastic layers. The dynamic analytical model of the structure is established to determine damping characteristics of the co-curing damping sandwich composite structure according to the structural geometric equation and constitutive relation. Rayleigh-Ritz method is employed to derive the modal natural frequency and modal loss factor of structure. The results of finite element simulation, theoretical derivation and modal test are in good agreement, which verifies the validity of the theoretical model and experimental design. It provides a theoretical basis for the design and application of composite structures with large damping and high stiffness.

High-performance control of fast tool servos with robust disturbance observer and modified [formula omitted] control

Fast tool servo (FTS) is an effective technique for the generation of complicated surfaces in modern precision manufacture industry. In this paper, a novel three-degree-of-freedom (3-DOF) control scheme is proposed for the FTS to achieve good tracking and disturbance rejection performance. Specifically, the 3-DOF control scheme contains a hysteresis compensation term, a modified H∞ feedback control term, a robust disturbance observer (RDOB) term and a feedforward control term. Firstly, a hysteresis compensator is developed based on the modified Prandtl–Ishlinskii (MPI) model to eliminate the intrinsic hysteresis nonlinearity so as to identify the linear dynamic model of the FTS system. A modified mixed-sensitivity-based H∞ feedback control is then proposed to simultaneously provide an excellent damping and tracking performance with a deliberately designed input weighting function. A RDOB is designed for non-minimum phase (NMP) system based on all-pass factorization of the linear dynamics model and the standard H∞ control framework to compensate uncertain external disturbances as well as unmodeled dynamics while guaranteeing the robust stability of closed-loop system. To remove phase delay and enlarge control bandwidth, a closed-loop-inversion feedforward controller is synthesized by integrating a zero-phase error tracking control (ZPETC) with a finite impulse response (FIR) filter. A series of comparative experiments are conducted on a self-developed flux-biased normal-stressed electromagnetic actuated FTS. The experimental results consistently validate the effectiveness and superiority of the proposed scheme in terms of outstanding tracking performance and disturbance rejection.

Compressive Mechanics and Hyperelasticity of Ni-Ti Lattice Structures Fabricated by Selective Laser Melting

Additively manufactured Ni-Ti lattice structures have controllable bio/mechanical properties, as well as excellent large deformation and damping properties similar to those of natural bone. They have broad application prospects in the field of bone implantation. Triply Periodic Minimal Surface (TPMS) structures are believed to be the most potential and ideal bionic bone structures. In this work, Ni-Ti Gyroid-type TPMS lattice structures were fabricated by selective laser melting (SLM) and their manufacturing fidelity and compression properties were evaluated. By changing the maximum strain value, the hyperelastic recovery performance under cyclic stress was investigated. The results showed that the Ni-Ti Gyroid lattice structures fabricated by SLM had excellent manufacturability (relative density can reach 98.93%) and mechanical properties (elastic modulus is about 130.8 MPa, ultimate strength is about 2.7 MPa). The hyperelastic cycle testing showed that the elastic modulus, yield strength and ultimate strength of the lattice structures tended to stablilize gradually with increasing numbers of cycles. The residual strain increased with the number of cycles, and as the maximum strain increased from 4% to 8%, the residual strain also increased from 1% to 4%.

Improving the mechanical and damping properties of polymer/memory alloy composite by introducing nanotubes covered with nano-scale Ni particles

Ni@CNT reinforced polymer/memory alloy damping composites were successfully fabricated by filling a porous CuAlMn shape memory alloy skeleton structure using polyurethane/epoxy interpenetrating network matrix. As 4 wt% Ni@CNT is dispersed in the polymer matrix, the loss factor (ratio of loss modulus to storage modulus) of the composite is above 0.09, and the maximum value can reach 0.156, at the whole test frequency (0.1 ∼ 200 Hz) and temperature (-10 ∼ 100 ℃) range. Meanwhile, its elastic modulus can reach 1137.9 MPa and the density is only 2.04 g/cm3. Compared with polymer/memory alloy composite, the average loss factor and elastic modulus of the prepared composite increased by 40.1% and 33.4%, respectively. A triphase damping model and a mechanical model were used to investigate the damping mechanism and elastic properties of composites, respectively. Calculation and simulation results indicated that the damping capacity of the Ni@CNT/polymer/memory alloy composite is basically related to interfacial dissipation, which is significantly enhanced via introducing nanotubes covered with nano-scale Ni particles. Due to the light weight, certain strength, good deformation resistance and excellent damping performance, this nanocomposite has potential applications in the damping field of aerospace.