Design and evaluation of vibration reducing seat suspension based on negative stiffness structure

2020 ◽  
Vol 234 (21) ◽  
pp. 4171-4189
Author(s):  
Ehsan Davoodi ◽  
Pedram Safarpour ◽  
Mahdi Pourgholi ◽  
Mostafa Khazaee
Keyword(s):  
Design Procedure ◽  
Vertical Vibration ◽  
Negative Stiffness ◽  
Transfer Path ◽  
Seat Suspension ◽  
Suspension Parameters ◽  
Payload Capacity ◽  
Simulation Results ◽  
Iso 2631 ◽  
Isolation Performance

The vibration transmitted to helicopter aircrew is the main health risk, specifically at low excitation frequencies. In this paper, to improve the vibration environment for aircrew, a seat suspension using a negative stiffness structure has been proposed. The main feature of the proposed system is the negative stiffness structure along with a traditional positive stiffness structure. Here, the dynamic model of the proposed system is derived and the design procedure for the seat suspension parameters is presented in order to mitigate the vibration transmitted to occupant and at the same time preserving payload capacity of the system. Then, the vibration transmitted to seat as well as the transmissibility of the proposed system at the steady state are evaluated using ISO-2631 and conventional criteria. To verify the validity of the simulation results, the reproduced signal of the cabin floor of the Bell-412 helicopter is applied. Results reveal that the isolation performance of the proposed system based on the negative stiffness structure is well-suited so that the values of root mean square and vibration dose value for seat’s vertical vibration in this structure are 0.0789 and 0.1254, respectively. It showed an almost 90% reduction of amplitude with respect to the cabin floor’s vibration. Also, according to the ISO-2631 standard, the level of comfort is improved from uncomfortable to not uncomfortable that represents the promotion of riding quality and improvement of vibration environment for aircrew. As well as results display that the frequency spectrum of the cabin floor and the seat are similar to each other and actually frequency modulation does not happen in the vibration transfer path between the cabin floor and over the seat.

Optimal Seat Suspension Design Based on Minimum “Simulated Subjective Response”

1997 ◽  
Vol 119 (4) ◽  
pp. 409-416 ◽  
Author(s):  
Y. Wan ◽  
J. M. Schimmels
Keyword(s):  
Vibration Isolation ◽  
Optimization Procedure ◽  
Vertical Vibration ◽  
Whole Body ◽  
Subjective Response ◽  
Seat Suspension ◽  
Suspension Parameters ◽  
Sensitivity Standard ◽  
Selection Of

This work addresses a method for improving vertical whole body vibration isolation through optimal seat suspension design. The primary thrusts of this investigation are: (1) the development of a simple model that captures the essential dynamics of a seated human exposed to vertical vibration, (2) the selection and evaluation of several standards for assessing human sensitivity to vertical vibration, and (3) the determination of the seat suspension parameters that minimize these standards to yield optimal vibration isolation. Results show that the optimal seat and cushion damping coefficients depend very much on the selection of the vibration sensitivity standard and on the lower bound of the stiffnesses used in the constrained optimization procedure. In all cases, however, the optimal seat damping obtained here is significantly larger (by than a factor of 10) than that obtained using existing seat suspension design methods or from previous optimal suspension studies. This research also indicates that the existing means of assessing vibration in suspension design (ISO 7096) requires modification.

The design of negative stiffness spring for precision vibration isolation using axially magnetized permanent magnet rings

2019 ◽  
Vol 25 (19-20) ◽  
pp. 2667-2677 ◽  
Author(s):  
Zhenhua Zhou ◽  
Shuhan Chen ◽  
Dun Xia ◽  
Jianjun He ◽  
Peng Zhang
Keyword(s):  
Vibration Isolation ◽  
Dynamic Stiffness ◽  
Low Frequency ◽  
Design Procedure ◽  
Air Gap ◽  
Negative Stiffness ◽  
Linear Component ◽  
Vibration Isolator ◽  
Stiffness Characteristic ◽  
Isolation Performance

A negative stiffness element is always employed to generate high-static–low-dynamic stiffness characteristic of the vibration isolator, reduce the resonance frequency of the isolator, and improve the vibration isolation performance under low and ultra-low frequency excitation. In this paper, a new compact negative stiffness permanent magnetic spring (NSPMS) that is composed of two axial-magnetized permanent magnetic rings is proposed. An analytical expression of magnetic negative stiffness of the NSPMS is deduced by using the Coulombian model. After analyzing the effect of air-gap width, air-gap position, height difference between the inner ring and outer ring on the negative stiffness characteristic, a design procedure is proposed to realize the negative stiffness characteristic with a global minimum linear component and uniformity stiffness near the equilibrium position. Finally, an experimental prototype is developed to validate the effectiveness of the NSPMS. The experimental results show that combining a vibration isolator with the NSPMS in parallel can lower the natural frequency and improve the isolation performance of the isolator.

scholarly journals Theoretical Modeling and Vibration Isolation Performance Analysis of a Seat Suspension System Based on a Negative Stiffness Structure

2021 ◽  
Vol 11 (15) ◽  
pp. 6928
Author(s):  
Xin Liao ◽  
Ning Zhang ◽  
Xiaofei Du ◽  
Wanjie Zhang
Keyword(s):  
Vibration Isolation ◽  
Vibration Suppression ◽  
Ride Comfort ◽  
Dynamic Stiffness ◽  
Suspension System ◽  
Negative Stiffness ◽  
Nonlinear Dynamic Model ◽  
Seat Suspension ◽  
Vibration Isolation Performance ◽  
Isolation Performance

In this study, to improve the vibration isolation performance of a cab seat and the ride comfort of the driver, we propose a mathematical model for a seat suspension system of a construction machinery cab based on a negative stiffness structure (NSS). First, a static analysis of a seat suspension system is conducted and the different parameters and their influences on the dynamic stiffness are discussed. Thereby, the ideal configuration parameter range of the suspension system is obtained. Moreover, the nonlinear dynamic model of the designed seat suspension system is established. The frequency response and the stability are analyzed by using the HBM method and numerical simulation. The vibration transmissibility characteristics and vibration suppression effects of the seat suspension system are presented in detail. The results show that, as compared with a quasi-zero-stiffness system, the QZS-IE system has higher vibration suppression advantages under large excitation and small damping, as well as lower transmissibility and a wider vibration isolation frequency range. In addition, an inerter element with a larger mass ratio and relatively shorter distance ratio is better for vibration isolation performance of the QZS-IE system in a practical engineering application. The results of this study provide a scientific basis for the design and improvement of a seat suspension system.

scholarly journals Design of cab seat suspension system for construction machinery based on negative stiffness structure

2021 ◽  
Vol 13 (8) ◽  
pp. 168781402110449
Author(s):  
Xin Liao ◽  
Xiaofei Du ◽  
Shaohua Li
Keyword(s):  
Vibration Isolation ◽  
Ride Comfort ◽  
Suspension System ◽  
Negative Stiffness ◽  
Construction Machinery ◽  
Seat Suspension ◽  
Vibration Transmissibility ◽  
Suspension Structure ◽  
Vibration Isolation Performance ◽  
Isolation Performance

In order to improve the vibration isolation performance of cab seat and ride comfort of the driver, a seat suspension structure of construction machinery cab is proposed based on negative stiffness structure (NSS) in this paper. The influences of different parameters of suspension system on dynamic stiffness are analyzed. The configuration parameter range of suspension system is obtained. Then, the nonlinear dynamic equation of the seat suspension system is established and the NSS optimization model is proposed. The vibration transmissibility characteristics of suspension structure are analyzed by different methods. The results show that the displacement and acceleration amplitude of optimized seat suspension system are obviously reduced, and the VDV and RMS in the vertical vibration direction for the seat are respectively decreased by 87% and 86%. The vibration transmissibility rate SEAT and the Ttrans are both decreased. Moreover, the peak frequencies of the vibration transmitted to the driver are not near the key frequency values which are easy to cause human discomfort. It indicates that the design of seat suspension system has no effect on the health condition of the driver after being vibrated. The advantages of vibration isolation performance of the designed NSS suspension system are demonstrated, improving the driver’s ride comfort and the working environment.

scholarly journals Improving Low Frequency Isolation Performance of Optical Platforms Using Electromagnetic Active-Negative-Stiffness Method

2020 ◽  
Vol 10 (20) ◽  
pp. 7342
Author(s):  
Yamin Zhao ◽  
Junning Cui ◽  
Junchao Zhao ◽  
Xingyuan Bian ◽  
Limin Zou
Keyword(s):  
Root Mean Square ◽  
Dynamic Stiffness ◽  
Low Frequency ◽  
Laser Interferometry ◽  
Relative Displacement ◽  
Negative Stiffness ◽  
Mean Square ◽  
Electromagnetic Actuators ◽  
Micro Vibration ◽  
Isolation Performance

To improve the low-frequency isolation performance of optical platforms, an electromagnetic active-negative-stiffness generator (EANSG) was proposed, using nano-resolution laser interferometry sensors to monitor the micro-vibration of an optical platform, and precision electromagnetic actuators integrated with a relative displacement feedback strategy to counteract the positive stiffness of pneumatic springs within a micro-vibration stroke, thereby producing high-static-low-dynamic stiffness characteristics. The effectiveness of the method was verified by both theoretical and experimental analyses. The experimental results show that the vertical natural frequency of the optical platform was reduced from 2.00 to 1.37 Hz, the root mean square of displacement was reduced from 1.28 to 0.69 μm, and the root mean square of velocity was reduced from 14.60 to 9.33 μm/s, proving that the proposed method can effectively enhance the low frequency isolation performance of optical platforms.

scholarly journals Ride Comfort Control System Considering Physiological and Psychological Characteristics: Effect of Masking on Vertical Vibration on Passengers

Actuators ◽  
2018 ◽  
Vol 7 (3) ◽  
pp. 42 ◽  
Author(s):  
Keigo Ikeda ◽  
Ayato Endo ◽  
Ryosuke Minowa ◽  
Takayoshi Narita ◽  
Hideaki Kato
Keyword(s):  
Heart Rate ◽  
Heart Rate Variability ◽  
Ride Comfort ◽  
Control Method ◽  
Vertical Vibration ◽  
Psychological Characteristics ◽  
Psychological State ◽  
Vibration Acceleration ◽  
Seat Suspension ◽  
Vibration Stress

Active seat suspension has been proposed to improve ride comfort for ultra-compact mobility. Regarding the ride comfort of passengers due to vertical vibration, the authors have confirmed from biometry measurements that reduction of the vibration acceleration does not always produce the best ride comfort for passengers. Therefore, heart rate variability that can quantitatively reflect stress is measured in real time, and a control method was proposed that feeds back to active suspension and confirms its effectiveness by fundamental verification. In this paper, we will confirm the influence of the vibration stress on the psychological state of the occupant by the masking method.

Novel dual-band multistrip monopole antenna with defected ground structure for WLAN/IMT/BLUETOOTH/WIMAX applications

2013 ◽  
Vol 6 (1) ◽  
pp. 93-100 ◽  
Author(s):  
Jaswinder Kaur ◽  
Rajesh Khanna ◽  
Machavaram Kartikeyan
Keyword(s):  
Wireless Local Area Network ◽  
Local Area Network ◽  
Design Procedure ◽  
Monopole Antenna ◽  
Dual Band ◽  
Impedance Bandwidth ◽  
Area Network ◽  
Defected Ground Structure ◽  
Ground Structure ◽  
Simulation Results

In the present work, a novel multistrip monopole antenna fed by a cross-shaped stripline comprising one vertical and two horizontal strips has been proposed for wireless local area network (WLAN)/Industrial, Scientific, and Medical band (ISM)/International Mobile Telecommunication (IMT)/BLUETOOTH/Worldwide Interoperability for Microwave Access (WiMAX) applications. The designed antenna has a small overall size of 20 × 30 mm2. The goal of this paper is to use defected ground structure (DGS) in the proposed antenna design to achieve dual-band operation with appreciable impedance bandwidth at the two operating modes satisfying several communication standards simultaneously. The antenna was simulated using Computer Simulation Technology Microwave Studio (CST MWS) V9 based on the finite integration technique (FIT) with perfect boundary approximation. Finally, the proposed antenna was fabricated and some performance parameters were measured to validate against simulation results. The design procedure, parametric analysis, simulation results along with measurements for this multistrip monopole antenna using DGS operating simultaneously at WLAN (2.4/5.8 GHz), IMT (2.35 GHz), BLUETOOTH (2.45 GHz), and WiMAX (5.5 GHz) are presented.

Stiffness Performance Simulation and Testing of a New Type Integrated Suspension Strut

2012 ◽  
Vol 472-475 ◽  
pp. 2760-2765
Author(s):  
Hao Bin Jiang ◽  
Ying Jun Du ◽  
Shen Chen Ye
Keyword(s):  
Mathematical Model ◽  
Fluid Mechanics ◽  
Vertical Vibration ◽  
Bench Test ◽  
Test Results ◽  
Performance Simulation ◽  
Body Roll ◽  
New Type ◽  
Simulation Results ◽  
Stiffness Characteristics

The design scheme of a new type strut was put forward, whose stiffness characteristics can undertake linkage control. The structure and basic principle of this new suspension component were introduced. According to fluid mechanics and thermodynamics, a mathematical model for the stroke dependent stiffness characteristics of the strut was established, and the stiffness characteristics were analyzed by using software SIMULINK. Then the stiffness performance bench test of the strut specimen was carried out for verification. Results show that the test results agree well with the simulation results. It is verified that the established mathematical model is correct and the stiffness of this strut shows nonlinear changes vary with the displacement of piston. When the suspension is largely impacted, the stiffness of this strut increases quickly which could restrain the wheel bouncing, body roll and vertical vibration.

Proportional Control of Dissolved Oxygen Concentration of Sewage Water Treatment in Oil Field

2013 ◽  
Vol 421 ◽  
pp. 798-802
Author(s):  
Chao Xie
Keyword(s):  
Water Treatment ◽  
Dissolved Oxygen ◽  
Activated Sludge ◽  
Design Procedure ◽  
Sewage Water ◽  
Oil Field ◽  
Dissolved Oxygen Concentration ◽  
Proportional Control ◽  
Simulation Results ◽  
Sewage Water Treatment

Activated sludge method is mainly used to sewage water treatment of water injection system in oil field, dissolved oxygen of sewage pond plays a important role in the sewage water treatment process. The proportional control algorithm of dissolved oxygen concentration is developed based on a first time delay model, and the parameter values of the controller is determined by using stability margins design approach. Simulation results are provided to illustrate the design procedure and the effectiveness of the proposed methods. When applying to the wastewater treatment system based on activated sludge, this method can achieve a satisfied treating performance with robustness. Simulation results are given to demonstrate the design procedure and the effectiveness of the proposed methods.

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