A Study of Pounding to Simulate Impact and Determine the Impact Damping Ratio

2015 ◽  
Author(s):  
H. Naderpour ◽  
R.C. Barros ◽  
S.M. Khatami
Keyword(s):  
Damping Ratio ◽  
The Impact ◽  
Impact Damping

scholarly journals Effective Formula for Impact Damping Ratio for Simulation of Earthquake-induced Structural Pounding

Geosciences ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 347 ◽  
Author(s):  
Seyed Mohammad Khatami ◽  
Hosein Naderpour ◽  
Rui Carneiro Barros ◽  
Anna Jakubczyk-Gałczyńska ◽  
Robert Jankowski
Keyword(s):  
Kinetic Energy ◽  
Impact Force ◽  
Damping Ratio ◽  
Dissipated Energy ◽  
Force Model ◽  
Single Collision ◽  
Structural Pounding ◽  
Impact Forces ◽  
The Impact ◽  
Impact Damping

Structural pounding during earthquakes may cause substantial damage to colliding structures. The phenomenon is numerically studied using different models of collisions. The aim of the present paper is to propose an effective formula for the impact damping ratio, as a parameter of the impact force model used to study different problems of structural pounding under seismic excitations. Its accuracy has been verified by four various approaches. Firstly, for the case of collisions between two structural elements, the dissipated energy during impact has been compared to the loss of kinetic energy. In the second stage of verifications, the peak impact forces during single collision have been analyzed. Then, the accuracy of different equations have been verified by comparing the impact force time histories for the situation when a concrete ball is dropped on a rigid concrete surface. Finally, pounding between two structures during earthquakes has been studied. The results of the analysis focused on comparison between dissipated and kinetic energy show relatively low errors between calculated and assumed values of the coefficient of restitution when the proposed equation is used. In addition, the results of the comparison between experimentally and numerically determined peak impact forces during single collision confirm the effectiveness of the approach. The same conclusion has been obtained for the whole impact time history for collision between a ball and a rigid surface. Finally, the results of the comparative analysis, conducted for pounding between two structures during an earthquake, confirm the simulation accuracy when the proposed approach is used. The above conclusions indicate that the proposed formula for impact damping ratio, as a parameter of impact force model for simulation of earthquake-induced structural pounding, is very effective and accurate in numerical simulations in the case of different scenarios.

scholarly journals Inversion for Damping Ratio of Flat Blade Based on BP Neural Network

Proceedings ◽  
2018 ◽  
Vol 2 (8) ◽  
pp. 547
Author(s):  
Xiamei Zhang ◽  
Shudan Xia
Keyword(s):  
Neural Network ◽  
Decay Time ◽  
Bp Neural Network ◽  
Damping Ratio ◽  
Drop Test ◽  
Analysis Model ◽  
Bp Network ◽  
The Real ◽  
Neural Network Inversion ◽  
The Impact

Aero engine is impacted by foreign objects frequently during daily usage, including runway gravel, birds, fuselage components and so on, so the fan and compressor may damage, resulting in serious air crash. Thus, simulating the impact of blades and establishing the numerical analysis model of dynamic response demand immediate attention. In the analysis model, damping coefficient is one of the most important physical parameters of the blade structure and cannot be directly measured. Rayleigh damping is widely applied and can be converted to direct modal damping in ABAQUS. BP neural network is a multi-layer feedforward neural network using back propagation algorithm to adjust the network weights. It can be proved that there exists a three-layer BP network to realize the mapping of arbitrary continuous functions with arbitrary precision. In this study, a novel method for obtaining the damping ratio of the flat blade which applies BP neural network inversion is proposed. In order to demonstrate this method, a simplified experiment was conducted. Firstly, fix a section of aluminum plate and then conduct two set of drop tests on different positions with different impact velocities by a steel ball. At the same time, vibration response was recorded by displacement sensor. Secondly, establish a finite element model using ABAQUS to simulate the drop test. Adopt twenty groups of models with different damping ratio and then obtain their amplitudes and decay time, respectively. Thirdly, train a BP neural network using MATLAB program and then establish the mapping relationship between amplitude, decay time and damping ratio. Fourth, a set of experimental amplitude and decay time is substituted into the previously obtained BP neural network mapping model, and then the real damping ratio is obtained by inference. Finally, the real damping ratio is applied to the flat blade impact simulation of the other set of drop test for validation. The numerical results are consistent with the experimental data, which indicates that the damping ratio obtained by BP neural network inversion is reasonable and reliable.

scholarly journals Assessing the Impact of DFIG Synthetic Inertia Provision on Power System Small-Signal Stability

Energies ◽  
2019 ◽  
Vol 12 (18) ◽  
pp. 3440 ◽  
Author(s):  
Edgar Lucas ◽  
David Campos-Gaona ◽  
Olimpo Anaya-Lara
Keyword(s):  
Power System ◽  
Large Scale ◽  
Damping Ratio ◽  
System Stability ◽  
Electrical Network ◽  
Small Signal ◽  
Small Signal Stability ◽  
Signal Stability ◽  
Electromechanical Modes ◽  
The Impact

Synthetic inertia provision through the control of doubly-fed induction generator (DFIG) wind turbines is an effective means of providing frequency support to the wider electrical network. There are numerous control topologies to achieve this, many of which work by making modifications to the DFIG power controller and introducing additional loops to relate active power to electrical frequency. How these many controller designs compare to one-another in terms of their contribution to frequency response is a much studied topic, but perhaps less studied is their effect on the small-signal stability of the system. The concept of small-signal stability in the context of a power system is the ability to maintain synchronism when subjected to small disturbances, such as those associated with a change in load or a loss of generation. Amendments made to the control system of a large-scale wind farm will inevitably have an effect on the system as a whole, and by making a DFIG wind turbine behave more like a synchronous generator, which synthetic inertia provision does, may incur consequences relating to electromechanical oscillations between generating units. This work compares the implications of two prominent synthetic inertia controllers of varying complexity and their effect on small-signal stability. Eigenvalue analysis is conducted to highlight the key information relating to electromechanical modes between generators for the two control strategies, with a focus on how these affect the damping ratios. It is shown that as the synthetic inertia controller becomes both more complex and more effective, the damping ratio of the electromechanical modes is reduced, signifying a decreased system stability.

The Impact of Road Construction Materials Dynamic Modulus Parameters on Road Surface Shearing Stress

2012 ◽  
Vol 178-181 ◽  
pp. 1183-1187
Author(s):  
Er Yong Chuo ◽  
De Qun Wang ◽  
Guo Rui Deng
Keyword(s):  
Surface Layer ◽  
Asphalt Pavement ◽  
Damping Ratio ◽  
Construction Materials ◽  
Road Surface ◽  
Shearing Stress ◽  
Wave Load ◽  
Layer Material ◽  
Driving Speed ◽  
The Impact

At the beginning,we used the ABAQUS to establish a two-dimensional finite element model of typical asphalt pavement, and analysised the changing axiom of road surface shearing stress under the half sine wave load. Also, we studied on the impact of damping ratio and the driving speed on shearing stress. Finally, by using SPSS13.0 software to compare the impact of speed, the surface layer material damping ratio, lower modulus ratio, the thickness of the surface layer and the thickness of the subbase. The results show that, to reduce the cracking damage caused by oversized shearing stress in asphalt pavement, we should first consider the damping ratio of surface layer material, and the most effective method is to use the road-building material of high damping ratio to prevent cracks, at the same time we should raise the driving speed.

Experimental study of passive vibration suppression using absorber with spherical ball impact damper

2016 ◽  
Vol 231 (17) ◽  
pp. 3193-3201 ◽  
Author(s):  
Riadh Chaari ◽  
Fathi Djemal ◽  
Fakher Chaari ◽  
Mohamed Slim Abbes ◽  
Mohamed Haddar
Keyword(s):  
Vibration Suppression ◽  
Industrial Applications ◽  
Design Parameters ◽  
Particle Impact ◽  
Ball Impact ◽  
Impact Damper ◽  
Ball Size ◽  
Wide Range ◽  
The Impact ◽  
Impact Damping

Impact dampers are efficient in many industrial applications with a wide range of frequencies. An experimental analysis of the impact damping of spherical balls is investigated to simplify the particle impact damping design and improve the vibration suppression. The objective of the study is to analyze some of the design parameters of impact damper using spherical balls. The experimental investigation consists to test the effect of the ball size for each mass level, the number of balls for each size level and different exciting force levels on vibrations of the main structure. The parametric study provided useful information to understand and optimize Particle Impact Damping design.

scholarly journals Dynamic Characteristics of Rubber Powder Modified Cement Asphalt Mortar

2012 ◽  
Vol 5 ◽  
pp. 243-246 ◽  
Author(s):  
Yun Liang Li ◽  
Yang Jian Ou ◽  
Yi Qiu Tan ◽  
Ming Yu Lu
Keyword(s):  
High Speed ◽  
Damping Ratio ◽  
Beam Specimen ◽  
Rubber Powder ◽  
Cement Asphalt Mortar ◽  
Track System ◽  
Vibration Attenuation ◽  
Vibration Tests ◽  
The Impact ◽  
Asphalt Mortar

Cement asphalt mortar (CA) is mainly applied in track system of high-speed railways for vibration attenuation. The impact on dynamics performance of CA with the admixture of rubber powder was studied. The beam specimen made of CA was manufactured for analyzing its vibration frequency and damping characteristics by free attenuation vibration tests. Results showed that there was no big change for fundamental frequency after admixture of rubber powder. However, high order frequency and structural damping increased with the increase of admixture amount. Damping ratio of CA was increased by admixing rubber powder, which can be better for energy absorption and vibration attenuation.

scholarly journals Seismic and Wind Analysis of Regular and Irregular RC Structures with Tuned Mass Damper

2019 ◽  
Vol 8 (3) ◽  
pp. 2263-2269
Keyword(s):  
Damping Ratio ◽  
Time History ◽  
Tuned Mass Damper ◽  
Ground Movement ◽  
Building Structures ◽  
Rc Structures ◽  
Dynamic Forces ◽  
Mass Damper ◽  
Rc Building ◽  
The Impact

Latest trend in the development high rise structure demanding taller and lighter structures, which are progressively adaptable with very low damping ratio. As the structures developing vertically, they are ending up all the more affecting by powerful excitation forces, for example, wind and seismic forces. For the more safety of structure and inhabitant's solace, the vibrations of the tall structures become a major issue for both structural designers. So as to control the vibration, various methodologies are proposed out of the few systems accessible for vibration control. Out of numerous methods, TMD has been observed to be increasingly powerful in controlling the dynamic forces caused due to seismic and wind excitations. In this paper, the adequacy of TMD in controlling the dynamic reaction of structures and the impact of different ground movement parameters on the seismic viability of TMD is researched. Essentially, a TMD is a vibratory subsystem appended to a bigger scale host structure so as to lessen the dynamic reactions. The frequency of damper will tuned to essential structure's frequency, so when frequency is high, the damper will results to resonate out of phase along with structural movement. The objective of this work is to study the impact of TMD on the dynamic forces brought about by seismic tremor and wind excitations in standard just as unpredictable in tall RC building structures. For that three 22 story RC building structures are considered with a similar arrangement out of which one ordinary regular structure and the other two are irregular RC structures are demonstrated in Etabs. In irregular RC structures, Stiffness irregularity and torsional irregularity are considered. For assessing seismic and wind reactions of structures, time history analysis, and static analysis used, with and without the tuned mass damper in ETABS. The outcomes acquired from the investigation of three 22 story RC structures with and without tuned mass damper are compared

scholarly journals Investigation on Damping Characteristics of Hydrostatic Bearing Film by Using Scale Method

2021 ◽  
Author(s):  
Sheng-Yen Hu ◽  
Wen-Chou Chen ◽  
Chien-Hsun Wang ◽  
Hsin-Ming Fu ◽  
Yuan Kang
Keyword(s):  
Damping Ratio ◽  
Resonant Peak ◽  
Test Results ◽  
Scaling Method ◽  
Single Degree Of Freedom ◽  
Hydrostatic Bearing ◽  
Damping Characteristics ◽  
Mass Spring ◽  
The Impact

Abstract The resonant peaks can be suppressed by damping, those effects is dependent on damping ratio of system. In this paper, we propose a scaling method to evaluate the damping ratio of hydrostatic bearings for the data from model test. This method fits specifically for the overdamping of all hydrostatic bearing. This is direct and the easiest method to obtain the damping characteristics of oil film for the lowest band before the first resonant peak. The frequency responses of acceleration per force for a single-degree-of-freedom mass-spring-damper model is used to generate the evaluation scales for the damping ratios of the modal test results of worktable mounting on hydrostatic bearing. The case study for experimental results of the impact response are evaluated for damping ratio of the hydrostatic film by these method. Furthermore, using this scaling method, the influences of three types of compensations on the damping ratio of a hydrostatic bearing are compared. The results reveal that the constant flow has the largest damping ratio, and the capillary restrictor has the smallest one.

scholarly journals Experimental and Analytical Characterization of Drop Impact Behavior for a Mobile Haptic Actuator

2017 ◽  
Author(s):  
Byungjoo Choi ◽  
Jiwoon Kwon ◽  
Yongho Jeon ◽  
Moon Gu Lee
Keyword(s):  
High Speed ◽  
Damping Ratio ◽  
Free Fall ◽  
Element Model ◽  
Impact Behavior ◽  
Air Resistance ◽  
Impact Reliability ◽  
The Impact ◽  
The Finite Element Model

Impact characterization of linear resonant actuator (LRA) is studied experimentally by newly developed drop tester, which can control various experimental uncertainty such as rotational moment, air resistance, secondary impact and so on. The feasibility of this test apparatus was verified by comparison with free fall test. By utilizing a high-speed camera and measuring the vibrational displacement of spring material, the impact behavior was captured and the damping ratio of the system was defined. Based on the above processes, the finite element model was established and the experimental and analytical results were successfully correlated. Finally, the damage of the system from impact loading can be expected by developed model and as a result, this research can improve the impact reliability of LRA.

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