Experimental Study on the Performance of the Laminated Steel Isolators

2013 ◽  
Vol 423-426 ◽  
pp. 1603-1607
Author(s):  
Yao Guo Xie ◽  
Ping He ◽  
Xian Qiang Qu ◽  
Hong Bin Cui
Keyword(s):  
Experimental Study ◽  
Vibration Isolation ◽  
Dynamic Stiffness ◽  
Damping Ratio ◽  
Dynamic Performance ◽  
Performance Testing ◽  
Stiffness Ratio ◽  
Static Stiffness ◽  
Comparison Of The Results

Through the analysis and comparison of the results of static and dynamic performance testing of a series of laminated steel pieces isolators used in the vibration isolation of warships, in the number and thickness of laminated steel pieces of the same circumstances, laminated steel arc and preload of test samples had a certain impact on the values ​​of static stiffness, dynamic stiffness, damping ratio as well as dynamic and static stiffness ratio.

scholarly journals A Full-Scale Experimental Study of the Vertical Dynamic and Static Behavior of the Pier-Cap-Pile System

2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Jianlei Liu ◽  
Meng Ma ◽  
Flavio Stochino
Keyword(s):  
Experimental Study ◽  
Bearing Capacity ◽  
Dynamic Stiffness ◽  
Soil Layer ◽  
Low Frequency ◽  
Full Scale ◽  
Single Pile ◽  
Static Stiffness ◽  
Loading Test ◽  
Test Technique

The bearing capacity evaluation of bridge substructures is difficult as the static loading test (SLT) cannot be employed for the bridges in services. As a type of dynamic nondestructive test technique, the dynamic transient response method (TRM) could be employed to estimate the vertical bearing capacity when the relationship between static stiffness and dynamic stiffness is known. The TRM is usually employed to evaluate single piles. For the pier-cap-pile system, its applicability should be investigated. In the present study, a novel full-scale experimental study, including both TRM test and SLT, was performed on an abandoned bridge pier with grouped pile foundation. The test included three steps: firstly, testing the intact pier-cap-pile system; then, cutting off the pier and testing the cap-pile system; finally, cutting off the cap and testing the single pile. The TRM test was repeatedly performed in the above three steps, whereas the SLT was only performed on the cap-pile system. Based on the experimental results, the ratio of dynamic and static stiffness of the cap-pile system was obtained. The results show that (1) in the low-frequency range (between 10 and 30 Hz in this study), the dynamic stiffness of the whole system is approximately four times of that of a single pile; (2) the ratio of dynamic and static stiffness of the cap-pile system tested in the study is approximately 1.74, which was similar to other tested values of a single pile; (3) to evaluate the capacity of similar cap-pile system and with similar soil layer conditions by TRM, the value of Kd/Ks tested in the study can be used as a reference.

scholarly journals Measurement Research of Motorized Spindle Dynamic Stiffness under High Speed Rotating

2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
Author(s):  
Xiaopeng Wang ◽  
Yuzhu Guo ◽  
Tianning Chen
Keyword(s):  
High Speed ◽  
Production Efficiency ◽  
Dynamic Stiffness ◽  
Damping Ratio ◽  
Dynamic Performance ◽  
Machining Accuracy ◽  
Motorized Spindle ◽  
Response Curves ◽  
Tool Technology ◽  
High Speed Machine

High speed motorized spindle has become a key functional unit of high speed machine tools and effectively promotes the development of machine tool technology. The development of higher speed and more power puts forward the stricter requirement for the performance of motorized spindle, especially the dynamic performance which affects the machining accuracy, reliability, and production efficiency. To overcome the problems of ineffective loading and dynamic performance measurement of motorized spindle, a noncontact electromagnetic loading device is developed. The cutting load can be simulated by using electromagnetic force. A new method of measuring force by force sensors is presented, and the steady and transient loading force could be measured exactly. After the high speed machine spindle is tested, the frequency response curves of the spindle relative to machine table are collected at 0~12000 rpm; then the relationships between stiffness and speeds as well as between damping ratio and speeds are obtained. The result shows that not only the static and dynamic stiffness but also the damping ratio declined with the increase of speed.

Parameters optimization of dynamic vibration absorber based on grounded stiffness, inerter, and amplifying mechanism

2021 ◽  
pp. 107754632110382
Author(s):  
Peng Sui ◽  
Yongjun Shen ◽  
Shaopu Yang ◽  
Junfeng Wang
Keyword(s):  
Analytical Solution ◽  
Vibration Isolation ◽  
Damping Ratio ◽  
Vibration Absorber ◽  
Primary System ◽  
Vibration Absorbers ◽  
Stiffness Ratio ◽  
Dynamic Vibration Absorber ◽  
Dynamic Vibration ◽  
Dynamic Vibration Absorbers

In the field of dynamics and control, some typical vibration devices, including grounded stiffness, inerter and amplifying mechanism, have good vibration isolation and reduction effects, especially in dynamic vibration absorber (DVA). However, most of the current research studies only focus on the performance of a single device on the system, and those DVAs are gradually becoming difficult to meet the growth of performance demand for vibration control. On the basis of Voigt dynamic vibration absorber, a novel dynamic vibration absorber model based on the combined structure of grounded stiffness, inerter, and amplifying mechanism is presented, and the analytical solution of the optimal design formula is derived. First, the motion differential equation of the system is established, and the normalized amplitude amplification factor of the displacement is calculated. It is found that the system has three fixed points unrelated to the damping ratio. The optimal frequency ratio is obtained based on the fixed-point theory. In order to ensure the stability of the system, it is found that inappropriate inerter coefficient will cause the system instable when screening optimal grounded stiffness ratio. Accordingly, the best working range of inerter is determined. Finally, optimal grounded stiffness ratio and approximate optimal damping ratio are also obtained. The influence of inerter coefficient and magnification ratio on the response of the primary system is analyzed. The correctness of the derived analytical solution is verified by numerical simulation. Compared with other dynamic vibration absorbers, it is verified that presented model has superior vibration absorption performance and provides a theoretical basis for the design of a new type of dynamic vibration absorbers.

Modal Analysis of Linear Guide Way Junction Surface

2013 ◽  
Vol 380-384 ◽  
pp. 105-108
Author(s):  
Sheng Le Ren ◽  
Tian Yu Cheng ◽  
Ye Dai
Keyword(s):  
Damping Ratio ◽  
Dynamic Performance ◽  
Surface Characteristics ◽  
Test Method ◽  
Joint Surface ◽  
Small Scale ◽  
Static Stiffness ◽  
Element Analysis ◽  
Scale Test ◽  
The Many

Rails is an affordable, fixed, direct the mobile device. Among the many factors that affect performance, the rail surface is a very important factor. This article use test method gets the static stiffness of joint surface and the top five bands of the natural frequency and damping ratio for small linear guides. Test access to the static stiffness will be important in finite element analysis of input parameters. In the course of the study, analysis of dynamic performance of small - scale test guide, Study on Effect of surface characteristics on the structure of the component. By comparing the small guide the results of the analysis and the experimental results to verify the validity and accuracy of the analysis method.

RESEARCH ON THE INFLUENCE OF SPRING STIFFNESS IN AN ER ISOLATOR

2005 ◽  
Vol 19 (07n09) ◽  
pp. 1635-1640
Author(s):  
JUAN WANG ◽  
SHAOHUA ZHANG
Keyword(s):  
Electric Field ◽  
Vibration Isolation ◽  
Dynamic Properties ◽  
Structural Parameters ◽  
Dynamic Stiffness ◽  
Dynamic Performance ◽  
Spring Stiffness ◽  
Isolation System ◽  
Tunable Range ◽  
Working Principle

In this paper, the problem of Electrorheological(ER) technology's application in the vibration isolation system is empirically studied. Based on the particular characteristics of the Electrorheological Fluids (ERF) tunable damping, a metal-spring ER isolator was designed and its working principle is mainly discussed. By theoretical analysis of its simplified physical model, the dynamic response of an ER isolator is frequency- and amplitude- dependent and sensitive to structural parameters. The controllable parameters here can be the system equivalent spring stiffness K and damping coefficient C of ERF. With experiment, the exertion of ER effect was controlled through the change of K and C. Consequently, the system dynamic stiffness, which is used to describe the dynamic properties of system isolation performance, can be changed obviously. According to the dynamic performance tests, the result confirmed that applying different electric field strength could change the dynamic peculiarity of the metal-spring ER isolator. The configuration design of the ER equipment, such as stiffness ratio of two fluid chambers and the size of the electric field, which are important factors for the tunable range of ER isolator.

The relationship between lower-body stiffness and dynamic performance

2014 ◽  
Vol 39 (10) ◽  
pp. 1144-1150 ◽  
Author(s):  
Elizabeth C. Pruyn ◽  
Mark Watsford ◽  
Aron Murphy
Keyword(s):  
Physical Performance ◽  
Female Athletes ◽  
Dynamic Stiffness ◽  
Dynamic Performance ◽  
Medial Gastrocnemius ◽  
Lower Body ◽  
Static Stiffness ◽  
Lateral Gastrocnemius ◽  
Performance Variables ◽  
The Relationship

Greater levels of lower-body stiffness have been associated with improved outcomes for a number of physical performance variables involving rapid stretch-shorten cycles. The aim of this study was to investigate the relationship between several measures of lower-body stiffness and physical performance variables typically evident during team sports in female athletes. Eighteen female athletes were assessed for quasi-static stiffness (myometry) for several isolated muscles in lying and standing positions. The muscles included the medial gastrocnemius (MedGast), lateral gastrocnemius, soleus, and Achilles tendon. Dynamic stiffness during unilateral hopping was also assessed. Participants were separated into relatively stiff and compliant groups for each variable. A number of significant differences in performance were evident between stiff and compliant subjects. When considering the quasi-static stiffness of the MedGast in lying and standing positions, relatively stiff participants recorded significantly superior results during agility, bounding, sprinting, and jumping activities. Stiffness as assessed by hopping did not discriminate between performance ability in any test. Relationships highlighted by MedGast results were supported by further significant differences in eccentric utilisation ratio and drop jump results between stiff and compliant groups for the lateral gastrocnemius and soleus in lying and standing positions. Higher levels of lower-body stiffness appear to be advantageous for females when performing rapid and (or) repeated stretch-shorten cycle movements, including sprinting, bounding, and jumping. Further, the stiffness of the MedGast is of particular importance during the performance of these activities. It is important for practitioners working with athletes in sports that rely upon these activities for success to consider stiffness assessment and modification.

Kinematics analysis and performance testing of 6-RR-RP-RR parallel platform with offset RR-hinges based on Denavit-Hartenberg parameter method

2021 ◽  
pp. 095440622097843
Author(s):  
Yang Zhang ◽  
Ha-si-ao-qi-er Han ◽  
Zhen-bang Xu ◽  
Chun-yang Han ◽  
Yang Yu ◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Dynamic Stiffness ◽  
Performance Testing ◽  
Simulation Method ◽  
Parameter Method ◽  
Parallel Mechanisms ◽  
Static Stiffness ◽  
Leg Length ◽  
Parallel Platform ◽  
Adjustment System

A six degrees-of-freedom parallel platform in a 6-RR-RP-RR configuration with high accuracy, high stiffness and a large working stroke is studied for application to the sub-mirror adjustment system of a large-aperture telescope. To meet the performance requirements, the parallel platform adopts a self-centering and well-designed offset universal hinge. The two hinge axes of the offset hinge do not intersect but have a specific offset in space, which makes the kinematics more complex than that with a common universal hinge. Therefore, to solve this complex kinematics problem, this paper innovatively introduces the Denavit–Hartenberg (D-H) parameter method that is used for series mechanisms. The method has a simple modeling process, strong applicability and continuity, providing a new tool for the analysis and application of the parallel mechanisms. A kinematics model of the parallel platform can be constructed and solved using a numerical iteration method. The accuracy of the numerical kinematics solution is verified using a co-simulation method. This paper analyses the passive derivative motion and the leg length error is compensated. Finally, test studies of the motion resolution, the repetitive positioning accuracy, the motion stroke, the static stiffness of the legs, and the static stiffness and dynamic stiffness of the entire machine were also carried out to verify the platform’s performance.

Experimental study on dynamic performance of typical nonballasted track systems using a full-scale test rig

2016 ◽  
Vol 231 (4) ◽  
pp. 470-481 ◽  
Author(s):  
Mingze Wang ◽  
Chengbiao Cai ◽  
Shengyang Zhu ◽  
Wanming Zhai
Keyword(s):  
Experimental Study ◽  
Dynamic Stiffness ◽  
Dynamic Performance ◽  
Full Scale ◽  
Damping Coefficient ◽  
Full Scale Test ◽  
Test Rig ◽  
Scale Test ◽  
Stiffness And Damping Coefficient ◽  
Stiffness And Damping

This paper presents an experimental study on dynamic performance of China Railway Track System (CRTS) series track systems using a full-scale test rig. The test rig has been constructed based on 55.17 m long full-scale nonballasted tracks composed of four typical CRTS track elements in high-speed railways. First, the dynamic characteristics of different nonballasted tracks are investigated by conducting wheel-drop tests, where a wheel-drop testing vehicle with a dropping wheelset is devised to provide the wheel-drop load. The vibration levels of different track systems are assessed by the root-mean-square acceleration per one-third octave band, and the vibration transmission characteristics of the CRTS series tracks are evaluated by transfer functions. Further, a mathematical track model is used to extract the dynamic stiffness and damping coefficient of the four types of nonballasted track systems based on the wheel–rail impact response. The vibration characteristics, the dynamic stiffness, and damping coefficient of different nonballasted track systems under various wheel-drop heights are compared and discussed in detail.

Design and Analysis of a High-Static-Low-Dynamic Stiffness Isolator Using the Cam-Roller-Spring Mechanism

2020 ◽  
Vol 142 (2) ◽  
Author(s):  
Yuhui Yao ◽  
Xiaojian Wang ◽  
Hongguang Li
Keyword(s):  
Harmonic Balance ◽  
Vibration Isolation ◽  
Dynamic Stiffness ◽  
Damping Ratio ◽  
Harmonic Balance Method ◽  
Interaction Force ◽  
Linear Spring ◽  
Cam Profile ◽  
Force Transmissibility ◽  
Spring Mechanism

Abstract This paper presents a new design of a high-static-low-dynamic stiffness (HSLDS) isolator with an adjustable cam profile. The interaction force between the cam and roller provides the negative stiffness force and the linear spring provides the positive stiffness force in the HSLDS isolator. Unlike previous studies, the cam profile in this paper can be individually designed to meet different working conditions. Firstly, the harmonic balance method is used to acquire the dynamic response of the HSLDS isolator. Then, the effects of the damping ratio, stiffness ratio, and external force amplitude on the frequency response amplitude and force transmissibility are discussed. Finally, the frequency responses of four designed nonlinear HSLDS isolators and a linear isolator are acquired by the numerical method. The results show that the nonlinear isolator begins to achieve vibration isolation at 0.11 Hz and the linear one is 8.9 Hz. The proposed HSLDS isolator realizes lower vibration isolation frequency than the linear isolator.

Optimal Design of the Vertical Machining Center Based on Stiffness Analysis

2011 ◽  
Vol 50-51 ◽  
pp. 68-72
Author(s):  
Yan Min Zhao ◽  
Zhi Jun Wu ◽  
Jian Fu Zhang ◽  
Ping Fa Feng ◽  
Ding Wen Yu
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Dynamic Stiffness ◽  
Dynamic Performance ◽  
Static Stiffness ◽  
Element Analysis ◽  
Stiffness Analysis ◽  
Machining Center ◽  
Before And After ◽  
Machine Stiffness

Stiffness analysis plays an important role in the optimization of the machine tool. By analyzing the static stiffness, dynamic stiffness and natural frequency of the key components, we discussed how to improve static and dynamic performance of the whole machine. Through the finite element analysis method, weak parts of the vertical machining center are firstly identified based on static stiffness analysis. Due to the purposes of increasing the stroke in Y-direction, improving the whole machine stiffness and without increasing the whole machine weight, optimal designs are carried out mainly on the structures of the spindle box and the column. And the performance of the parts and the whole machine before and after optimization is compared by testing whether the stiffness is improved or not. We also conducted experiments, and the results are consistent with the results of finite element analysis.

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