Vibration Isolation Research on the Metal Rubber Damping Rod of Payload Attach Fitting

2011 ◽  
Vol 391-392 ◽  
pp. 467-473 ◽  
Author(s):  
Zhan Ji Wei ◽  
Dong Xu Li ◽  
Rui Xu
Keyword(s):  
High Frequency ◽  
Vibration Isolation ◽  
Resonant Peak ◽  
Vibration Load ◽  
Equivalent Damping ◽  
Damping Characteristics ◽  
Metal Rubber ◽  
Vibration Parameters ◽  
Stiffness And Damping ◽  
Damping Model

In order to reduce the vibration load transmitted from the launch vehicle to the spacecraft during the launching stage, a whole-spacecraft vibration isolating method is advanced by modifying ordinary payload attach fitting (PAF). The core component of the PAF is a kind of damping rod produced by composite material encapsulating metal rubber (MR). In this paper, nonlinear equivalent damping model of the damping rod is built up. By using the model, the stiffness, damping and the transmissibility of the damping rod is studied attentively. Simulation results demonstrate that there exist nonlinear relationships between vibration parameters and the stiffness and damping characteristics of the damping rod. The damping rod can isolate high-frequency vibration as well as restrain the resonant peak effectively.

Research on Stiffness and Damping Characteristics of Fixed Oily Porous Materials Joint Interface

2011 ◽  
Vol 422 ◽  
pp. 575-579
Author(s):  
Chong Nian Qu ◽  
Liang Sheng Wu ◽  
Jian Feng Ma ◽  
Yi Chuan Xiao
Keyword(s):  
Porous Material ◽  
Porous Materials ◽  
Parallel Plate ◽  
Joint Interface ◽  
Force Model ◽  
Equivalent Stiffness ◽  
Contact State ◽  
Damping Characteristics ◽  
Stiffness And Damping ◽  
Damping Model

In this document, using the anti-squeezed force model in the narrow parallel plate when fluid is squeezed, the equivalent stiffness and damping model is derived. It is further verified that it can increase the stiffness and damping while there are oil between the joint interfaces theoretically. Because the contact state of oily porous material can divide into liquid and solid parts, the document supposes that it is correct and effective to think the stiffness and damping of the two parts as shunt connection.

Shock and Vibration Isolation Using Dynamic Mounts With Internal Damping

2018 ◽  
Author(s):  
Theresa Blandino ◽  
Aldo Ferri
Keyword(s):  
Vibration Isolation ◽  
Optimal Level ◽  
Internal Damping ◽  
Damping Characteristics ◽  
Isolation Systems ◽  
Different Response ◽  
High Level ◽  
Stiffness And Damping ◽  
Isolation Performance

Shock isolation systems are often modeled as having lumped stiffness and damping characteristics. However, the isolation performance may be improved if the isolation mount is allowed to have internal dynamics. Previous work has considered several different ways of disrupting the disturbance as it propagates along the length of a multi-degree-of-freedom mount. In this paper, the role of internal damping of the mount is re-examined. Furthermore, the damping model is extended to allow different levels of damping in different response regimes. Through simulation of the shock response, the findings show that the optimal level of internal damping depends on the magnitude of the input shock. For small shocks, performance is best for a relatively high level of damping, but for larger shocks, the best damping value drops to a much lower value. The effect on isolation performance of having different damping levels in different response regimes is shown to be fairly modest, and is shown to depend on the input excitation level.

Experimental Evaluation of Magnetorheological Damper Characteristics for Vibration Analysis

2018 ◽  
Vol 10 (1) ◽  
Author(s):  
S. Siva Kumar ◽  
K.S. Raj Kumar ◽  
Navaneet Kumar
Keyword(s):  
Vibration Isolation ◽  
Mr Damper ◽  
Magnetorheological Damper ◽  
Damping Force ◽  
Mr Fluid ◽  
Damping Characteristics ◽  
Fluid Damper ◽  
Mr Fluid Damper ◽  
Stiffness And Damping ◽  
Theoretical Results

Magnetorheological (MR) fluid damper has been designed, fabricated and tested to find the stiffness and damping characteristics. Experimentally the MR damper has been tested to analyse the behaviour of MR fluid as well as to obtain the stiffness for varying magnetic field. MR damper mathematical model has been developed for evaluating dynamic response for experimentally obtained parameters. The experimental results show that the increase of applied electric current in the MR damper, the damping force will increase remarkably up to the saturation value of current. The numerical simulation results that stiffness of the MR damper can be varied with the current value and increase the damping forces with the reduced amplitude of excitation. Experimental and theoretical results of the MR damper characteristics demonstrate that the developed MR damper can be used for vibration isolation and suppression.

scholarly journals Dynamic Performance of Laminated High-Damping and High-Stiffness Composite Structure Composed of Metal Rubber and Silicone Rubber

Materials ◽  
2021 ◽  
Vol 14 (1) ◽  
pp. 187
Author(s):  
Xiaoyuan Zheng ◽  
Zhiying Ren ◽  
Liangliang Shen ◽  
Bin Zhang ◽  
Hongbai Bai
Keyword(s):  
Silicone Rubber ◽  
Composite Structure ◽  
Dynamic Stiffness ◽  
Damping Properties ◽  
Damping Characteristics ◽  
Vibration Excitation ◽  
Metal Rubber ◽  
Damping Materials ◽  
Stiffness And Damping ◽  
Laminated Structures

In this study, a laminated composite damping structure (LCDS) with metal rubber (MR) as matrix and silicone rubber (SR) as reinforcement has been designed. The embedded interlocking structure formed by the multi-material interface of the LCDS can effectively incorporate the high damping characteristics of traditional polymer damping materials and significantly enhance the adjustable stiffness of the damping structure. Based on the periodic cyclic vibration excitation, dynamic tests on different laminated structures were designed, and the damping performance and fatigue characteristics under periodic vibration excitation of the LCDS, based on MR and SR, were explored in depth. The experimental results exhibited that, compared to single-compound damping structures, the LCDS with SR as reinforcement and MR as matrix has excellent stiffness and damping characteristics. The incorporation of the silicon-based reinforcement can significantly improve the performance of the entire structure under cyclic fatigue vibration. In particular, the effects of material preparation and operating parameters on the composite structure are discussed. The effects of MR matrix density, operating frequency, amplitude, and preload on the stiffness and damping properties of the MR- and SR-based LCDS were investigated by the single factor controlled variable method. The results demonstrated that the vibration frequency has little effect on the LCDS damping performance. By increasing the density of the MR matrix or increasing the structural preload, the energy dissipation characteristics and damping properties of the LCDS can be effectively improved. With the increase in vibration excitation amplitude, the energy consumption of the LCDS increases, and the average dynamic stiffness changes at different rates, resulting in the loss factor decreasing first and then increasing. In this study, a damping structure suitable for narrow areas has been designed, which overcomes the temperature intolerance and low stiffness phenomena of traditional polymer rubber materials, and provides effective guidance for the design of damping materials with controllable high damping and stiffness.

Improved Vibration Isolating Seat Suspension Designs Based on Position-Dependent Nonlinear Stiffness and Damping Characteristics

2003 ◽  
Vol 125 (3) ◽  
pp. 330-338 ◽  
Author(s):  
Yi Wan ◽  
Joseph M. Schimmels
Keyword(s):  
Vibration Isolation ◽  
Weighted Average ◽  
Coupled System ◽  
Lumped Parameter Model ◽  
Design Parameters ◽  
Seat Suspension ◽  
Damping Characteristics ◽  
Nonlinear Mechanical ◽  
Nonlinear Force ◽  
Stiffness And Damping

The design of seat suspensions having linear stiffness and damping characteristics involves a tradeoff between three performance measures. These measures are: (1) suspension range of motion, (2) improved average vibration isolation (weighted average across a wide exposure spectrum), and (3) improved isolation at the frequency of peak transmissibility. To overcome the limitations associated with this tradeoff, nonlinear mechanical properties are used here in the design of a seat suspension. From the infinite number of possible nonlinear mechanical characteristics, several possibilities that showed promise in previous studies were selected. The selected nonlinear force-deflection relationship (stiffness) of the seat is described by a combination of cubic and linear terms. The selected damping behavior of the seat is described by a combination of a linear term and a position-dependent term. A lumped parameter model (linear-human/nonlinear-seat) of the human/seat-suspension coupled system and a robust direct search routine are used to obtain pseudo-optimal values of the seat design parameters (mass, stiffness, and damping) via simulation in the time domain. Results indicate that the optimal nonlinear seat suspension is significantly better than the optimal linear seat suspension in overall vibration isolation characteristics.

Theoretical and Experimental Investigation on Nonlinear Characterization of Metal Rubber

2011 ◽  
Author(s):  
Jie Hong ◽  
Bin Zhu ◽  
Yanhong Ma
Keyword(s):  
Engineering Application ◽  
Theoretical Method ◽  
Nonlinear Stiffness ◽  
Space Technology ◽  
Material Parameters ◽  
Damping Characteristics ◽  
Manufacture Process ◽  
Metal Rubber ◽  
Rubber Component ◽  
Stiffness And Damping

Metal Rubber (MR) can be widely used in many aspects such as damping of blade and support, pipe and equipment in air space technology, vehicle and ship. A theoretical method was performed to describe hysteretic properties and nonlinear stiffness and damping characteristics of Metal Rubber component. Spiral wire was considered as the micro-element structure of MR material by analyzing the manufacture process of MR component. Based on the material mechanics and coulomb friction theory, a mechanical model of spiral wire was established which is combined with the cylindrical compression coil spring theory. It was easy to explain the mechanism of hysteresis loop and the nonlinear stiffness and damping characteristic of MR component by means of analyzing contact conditions of micro-element. The quasi-static experiments were conducted to MR component with different material parameters. The influencing laws of material parameters on the performance of MR component were studied. The research was valuable for the analysis of the material mechanics and the design of MR component. It provides theoretical support for the further engineering application of MR material in the field of vibration reduction.

Dynamic characteristics of squeeze-type mount using magnetorheological fluid

2005 ◽  
Vol 219 (1) ◽  
pp. 27-34 ◽  
Author(s):  
Y K Ahn ◽  
J-Y Ha ◽  
Y-H Kim ◽  
B-S Yang ◽  
M Ahmadian ◽  
...  
Keyword(s):  
Dynamic Characteristics ◽  
Experimental Analysis ◽  
Vibration Isolation ◽  
Dynamic Behaviour ◽  
Electrical Current ◽  
Magnetorheological Fluid ◽  
Test Set ◽  
Mr Fluid ◽  
Set Up ◽  
Stiffness And Damping

This paper presents an analytical and experimental analysis of the characteristics of a squeeze-type magnetorheological (MR) mount which can be used for various vibration isolation areas. The concept of the squeeze-type mount and details of the design of a squeeze-type MR mount are discussed. These are followed by a detailed description of the test set-up for evaluating the dynamic behaviour of the mount. A series of tests was conducted on the prototype mount built for this study, in order to characterize the changes occurring as a result of changing electrical current to the mount. The results of this study show that increasing electrical current to the mount, which increases the yield stress of the MR fluid, will result in an increase in both stiffness and damping of the mount. The results also show that the mount hysteresis increases with increase in current to the MR fluid, causing changes in stiffness and damping at different input frequencies.

Rotordynamic Performance of a Rotor Supported on Bump Type Foil Gas Bearings: Experiments and Predictions

2006 ◽  
Vol 129 (3) ◽  
pp. 850-857 ◽  
Author(s):  
Luis San Andrés ◽  
Dario Rubio ◽  
Tae Ho Kim
Keyword(s):  
High Speed ◽  
Critical Speed ◽  
Load Capacity ◽  
Test System ◽  
Foil Bearings ◽  
Rotor Imbalance ◽  
Synchronous Motion ◽  
Damping Characteristics ◽  
Rotor Surface ◽  
Stiffness And Damping

Gas foil bearings (GFBs) satisfy the requirements for oil-free turbomachinery, i.e., simple construction and ensuring low drag friction and reliable high speed operation. However, GFBs have a limited load capacity and minimal damping, as well as frequency and amplitude dependent stiffness and damping characteristics. This paper provides experimental results of the rotordynamic performance of a small rotor supported on two bump-type GFBs of length and diameter equal to 38.10mm. Coast down rotor responses from 25krpm to rest are recorded for various imbalance conditions and increasing air feed pressures. The peak amplitudes of rotor synchronous motion at the system critical speed are not proportional to the imbalance introduced. Furthermore, for the largest imbalance, the test system shows subsynchronous motions from 20.5krpm to 15krpm with a whirl frequency at ∼50% of shaft speed. Rotor imbalance exacerbates the severity of subsynchronous motions, thus denoting a forced nonlinearity in the GFBs. The rotor dynamic analysis with calculated GFB force coefficients predicts a critical speed at 8.5krpm, as in the experiments; and importantly enough, unstable operation in the same speed range as the test results for the largest imbalance. Predicted imbalance responses do not agree with the rotor measurements while crossing the critical speed, except for the lowest imbalance case. Gas pressurization through the bearings’ side ameliorates rotor subsynchronous motions and reduces the peak amplitudes at the critical speed. Posttest inspection reveal wear spots on the top foils and rotor surface.

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