scholarly journals Design and evaluation of a quasi-zero-stiffness isolator using flexibly supported negative stiffness mechanism

2021 ◽  
Vol 233 ◽  
pp. 03052
Author(s):  
Yu Lou ◽  
Peng Zhou
Keyword(s):  
Parametric Analysis ◽  
Design Method ◽  
External Disturbance ◽  
Cost Effective ◽  
Negative Stiffness ◽  
Equivalent Model ◽  
Isolation System ◽  
Flexible Support ◽  
Negative Stiffness Mechanism ◽  
Effective Design

In traditional quasi-zero-stiffness (QZS) isolation system, the negative stiffness part is usually fixed rigidly, lacking of effective amplifying mechanism. For reaching a quasi-zero state, the value of negative stiffness need to be very large to offset the positive stiffness of the structure. This paper proposes a novel isolator incorporating a flexible support to magnify negative stiffness part for effective realization of quasi-zero state. First, the concept and formulation of the innovative quasi-zero isolator are presented. Equivalent model for the flexibly supported negative stiffness part is established, followed by a parametric analysis to reveal the amplification effect. Thereafter, a design method is developed and numerical simulation is performed to verify the isolating performance. The results show that a flexible support enlarges the negative stiffness remarkably, thereby resulting in a cost-effective design. The optimized QZS isolator is capable of isolating external disturbance significantly.

scholarly journals Vibration Isolation System with Kalman Filter Estimated Acceleration Feedback: An Approach of Negative Stiffness Control

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Mhia Md Zaglul Shahadat ◽  
Takeshi Mizuno ◽  
Masaya Takasaki ◽  
Fazlur Rashid ◽  
Yuji Ishino
Keyword(s):  
Kalman Filter ◽  
Vibration Isolation ◽  
Ground Vibration ◽  
Negative Stiffness ◽  
Isolation System ◽  
Vibration Isolation System ◽  
Acceleration Feedback ◽  
Low Stiffness ◽  
Negative Stiffness Mechanism ◽  
Isolation Systems

This paper presents the isolation of vibration through the acceleration feedback of the Kalman filter. In this paper, vibration isolation was analyzed both analytically and experimentally through the estimation of the Kalman filter (KF). A negative stiffness mechanism was used to reduce the level of vibration for the developed dynamic system. The technique of negative stiffness can provide stiffness of infinite level to low stiffness as well as disturbance generated by the ground vibration directly. The performance of an isolation system through a mechanism of negative stiffness was improved by the addition of acceleration feedback. Acceleration was measured using a microelectromechanical (MEMS) type accelerometer instead of traditional servo type accelerometers due to lower cost. However, the output of a microelectromechanical (MEMS) type accelerometer is usually noisy. To avoid this difficulty, an acceleration that was estimated by a Kalman filter was considered in the acceleration feedback instead of directly measured acceleration. The dynamic behaviors of the system were compared for both the Kalman-filtered acceleration and the directly measured acceleration feedback. It is observed that the former has a significant effect on the improvement of the characteristics of the vibration isolation systems than later.

Design and analysis of a vibration isolation system with cam–roller–spring–rod mechanism

2021 ◽  
pp. 107754632110005
Author(s):  
Yonglei Zhang ◽  
Guo Wei ◽  
Hao Wen ◽  
Dongping Jin ◽  
Haiyan Hu
Keyword(s):  
Vibration Isolation ◽  
Dynamic Stiffness ◽  
Experimental Studies ◽  
Excitation Amplitude ◽  
Isolation System ◽  
Vibration Isolation System ◽  
Stiffness Characteristic ◽  
Negative Stiffness Mechanism ◽  
Isolation Systems ◽  
Vibration Isolation Performance

The vibration isolation system using a pair of oblique springs or a spring-rod mechanism as a negative stiffness mechanism exhibits a high-static low-dynamic stiffness characteristic and a nonlinear jump phenomenon when the system damping is light and the excitation amplitude is large. It is possible to remove the jump via adjusting the end trajectories of the above springs or rods. To realize this idea, the article presents a vibration isolation system with a cam–roller–spring–rod mechanism and gives the detailed numerical and experimental studies on the effects of the above mechanism on the vibration isolation performance. The comparative studies demonstrate that the vibration isolation system proposed works well and outperforms some other vibration isolation systems.

Price structures for electricity supply and potential consequences for building services systems

2021 ◽  
pp. 014362442199081
Author(s):  
Roger Hitchin
Keyword(s):  
Cost Effective ◽  
Building Design ◽  
Electricity Supply ◽  
Cooling Systems ◽  
Price Structure ◽  
Heating And Cooling ◽  
Future System ◽  
The Cost ◽  
Supply Systems ◽  
Effective Design

Policies to reduce carbon emissions are leading to substantial changes in the demand for electricity and to the structure of electricity supply systems, which will alter the cost structure of electricity supply. This can be expected to result in corresponding changes to the price structure faced by customers. This note is an initial exploration of how possible new price structures may impact on HVAC system and building design and use. Changes in the price structure of electricity supply (separately from changes in price levels) can significantly affect the cost-effective design and operation of building services systems; especially of heating and cooling systems. The nature and implications of these changes can have important implications for future system design and operation.

scholarly journals Co-Design of CVT-Based Electric Vehicles

Energies ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1825
Author(s):  
Caiyang Wei ◽  
Theo Hofman ◽  
Esin Ilhan Caarls
Keyword(s):  
Cooling System ◽  
Design Method ◽  
Low Cost ◽  
Cost Effective ◽  
Speed Ratio ◽  
Air Flow Rate ◽  
Cost Of Ownership ◽  
Variable Transmission ◽  
Primary Focus ◽  
Design Freedom

For an electric vehicle (EV) with a continuously variable transmission (CVT), a novel convex programming (CP)-based co-design method is proposed to minimize the total-cost-of-ownership (TCO). The integration of the electric machine (EM) and the CVT is the primary focus. The optimized system with co-design reduces the TCO by around 5.9% compared to a non-optimized CVT-based EV (based on off-the-shelf components) and by around 2% compared to the EV equipped with a single-speed transmission (SST). By taking advantage of the control and design freedom provided by the CVT, the optimal CVT, EM and battery sizes are found to reduce the system cost. It simultaneously finds the optimal CVT speed ratio and air-flow rate of the cooling system reducing the energy consumption. The strength of co-design is highlighted by comparing to a sequential design, and insights into the design of a low-power EV that is energy-efficient and cost-effective for urban driving are provided. A highly integrated EM-CVT system, which is efficient, low-cost and lightweight, can be expected for future EV applications.

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