scholarly journals Dropping Shock Characteristics of the Suspension Cushioning System with Critical Components

2017 ◽  
Vol 2017 ◽  
pp. 1-12 ◽  
Author(s):  
Hui Li ◽  
Anjun Chen ◽  
Ningning Duan
Keyword(s):  
Frequency Ratio ◽  
Dynamic Properties ◽  
Damping Ratio ◽  
Boundary Surface ◽  
Boundary Curve ◽  
Suspension System ◽  
Numerical Results ◽  
Shock Response ◽  
Response Peak ◽  
Critical Components

Dimensionless dropping shock dynamic equations of suspension nonlinear packaging system with critical components were obtained. The numerical results of shock response were gained using Runge-Kutta method. To evaluate the dropping shock characteristics of critical components, the dropping damage boundary curve was established, where the system parameter and the dimensionless shock velocity were selected as two coordinate parameters. Then, the frequency ratio and the system damping ratio were taken as third basic parameters of the dropping damage boundary surface, respectively. To study dynamic properties of the suspension system with critical components, the shock response acceleration, shock response displacements, and dropping damage boundary were analyzed. Based on the numerical results, the effects of the relevant parameters on dropping shock response and damage boundary of critical component were investigated. It is demonstrated that both a higher frequency ratio and a system damping ratio in the specific range can exert a positive effect on the product protection and should be selected in design process of the suspension system. Furthermore, with the decrease of suspension angle, the acceleration response peak decreases, the displacement response peak increases, and the safety zone enlarges.

scholarly journals The Dynamic Evaluation of Tilted Support Spring Nonlinear System with Critical Components under the Action of a Rectangular Pulse

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Ningning Duan ◽  
Shuang Song ◽  
Anjun Chen
Keyword(s):  
Nonlinear System ◽  
Pulse Duration ◽  
Frequency Ratio ◽  
Three Dimensional ◽  
Response Spectra ◽  
Rectangular Pulse ◽  
Numerical Results ◽  
Dynamical Equations ◽  
Shock Response ◽  
Critical Components

Dimensionless nonlinear dynamical equations of a tilted support spring nonlinear system with critical components were obtained under the action of a rectangular pulse, and the numerical results of the shock response were studied using Runge-Kutta method. To evaluate the dynamic characteristics of critical components, a new concept of three-dimensional shock response spectra was proposed, where the ratio of the maximum shock response acceleration of critical components to the peak pulse acceleration, the pulse duration, and the frequency ratio were three basic parameters of three-dimensional shock response spectra. Based on the numerical results, the effects of the angle, the peak pulse acceleration, the mass ratio, the frequency ratio, and the pulse duration on the shock response spectra were discussed.

scholarly journals The Shock Characteristics of Tilted Support Spring Packaging System with Critical Components

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
An-Jun Chen
Keyword(s):  
Frequency Ratio ◽  
Response Spectrum ◽  
Three Dimensional ◽  
Frequency Parameter ◽  
Mass Ratio ◽  
Packaging System ◽  
Parameter Ratio ◽  
Shock Response ◽  
Shock Response Spectrum ◽  
Critical Components

The nonlinear dynamical equations of tilted support spring packaging system with critical components were obtained under the action of half-sine pulse. To evaluate the shock characteristics of the critical components, a new concept of three-dimensional shock response spectrum was proposed. The ratio of the maximum shock response acceleration of the critical components to the peak pulse acceleration, the dimensionless pulse duration, and the frequency parameter ratio of system or the angle of tilted support spring system were three basic parameters of the three-dimensional shock response spectrum. Based on the numerical results, the effects of the peak pulse acceleration, the angle of the tilted support spring, the frequency parameter ratio, and the mass ratio on the shock response spectrum were discussed. It is shown that the effects of the angle of the tilted support spring and the frequency ratio on the shock response spectrum are particularly noticeable, increasing frequency parameter ratio of the system can obviously decrease the maximum shock response acceleration of the critical components, and the peak of the shock response of the critical components can be decreased at low frequency ratio by increasing mass ratio.

scholarly journals Damage Evaluation of Critical Components of Tilted Support Spring Nonlinear System under a Rectangular Pulse

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Ningning Duan ◽  
Meng Hao ◽  
Anjun Chen
Keyword(s):  
Nonlinear System ◽  
Damping Ratio ◽  
Damage Zone ◽  
Boundary Surface ◽  
Rectangular Pulse ◽  
Frequency Parameter ◽  
Mass Ratio ◽  
Dynamical Equations ◽  
Parameter Ratio ◽  
Critical Components

Dimensionless nonlinear dynamical equations of a tilted support spring nonlinear packaging system with critical components were obtained under a rectangular pulse. To evaluate the damage characteristics of shocks to packaged products with critical components, a concept of the damage boundary surface was presented and applied to a titled support spring system, with the dimensionless critical acceleration of the system, the dimensionless critical velocity, and the frequency parameter ratio of the system taken as the three basic parameters. Based on the numerical results, the effects of the frequency parameter ratio, the mass ratio, the dimensionless peak pulse acceleration, the angle of the system, and the damping ratio on the damage boundary surface of critical components were discussed. It was demonstrated that with the increase of the frequency parameter ratio, the decrease of the angle, and/or the increase of the mass ratio, the safety zone of critical components can be broadened, and increasing the dimensionless peak pulse acceleration or the damping ratio may lead to a decrease of the damage zone for critical components. The results may lead to a thorough understanding of the design principles for the tilted support spring nonlinear system.

scholarly journals Evaluation of Dynamic Properties of Sodium-Alginate-Reinforced Soil Using A Resonant-Column Test

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2743
Author(s):  
Seongnoh Ahn ◽  
Jae-Eun Ryou ◽  
Kwangkuk Ahn ◽  
Changho Lee ◽  
Jun-Dae Lee ◽  
...  
Keyword(s):  
Shear Modulus ◽  
Sodium Alginate ◽  
Shear Failure ◽  
Dynamic Properties ◽  
Damping Ratio ◽  
Reinforced Soil ◽  
Resonant Column ◽  
Column Test ◽  
Alginate Solution ◽  
Resonant Column Test

Ground reinforcement is a method used to reduce the damage caused by earthquakes. Usually, cement-based reinforcement methods are used because they are inexpensive and show excellent performance. Recently, however, reinforcement methods using eco-friendly materials have been proposed due to environmental issues. In this study, the cement reinforcement method and the biopolymer reinforcement method using sodium alginate were compared. The dynamic properties of the reinforced ground, including shear modulus and damping ratio, were measured through a resonant-column test. Also, the viscosity of sodium alginate solution, which is a non-Newtonian fluid, was also explored and found to increase with concentration. The maximum shear modulus and minimum damping ratio increased, and the linear range of the shear modulus curve decreased, when cement and sodium alginate solution were mixed. Addition of biopolymer showed similar reinforcing effect in a lesser amount of additive compared to the cement-reinforced ground, but the effect decreased above a certain viscosity because the biopolymer solution was not homogeneously distributed. This was examined through a shear-failure-mode test.

scholarly journals Identification of Dynamic Parameters of Pedestrian Walking Model Based on a Coupled Pedestrian–Structure System

2021 ◽  
Vol 11 (14) ◽  
pp. 6407
Author(s):  
Huiqi Liang ◽  
Wenbo Xie ◽  
Peizi Wei ◽  
Dehao Ai ◽  
Zhiqiang Zhang
Keyword(s):  
Negative Correlation ◽  
Dynamic Properties ◽  
Damping Ratio ◽  
Field Testing ◽  
The Body ◽  
Structural Vibration ◽  
Pedestrian Dynamics ◽  
Structure Interaction ◽  
Mass Spring ◽  
Stiffness And Damping

As human occupancy has an enormous effect on the dynamics of light, flexible, large-span, low-damping structures, which are sensitive to human-induced vibrations, it is essential to investigate the effects of pedestrian–structure interaction. The single-degree-of-freedom (SDOF) mass–spring–damping (MSD) model, the simplest dynamical model that considers how pedestrian mass, stiffness and damping impact the dynamic properties of structures, is widely used in civil engineering. With field testing methods and the SDOF MSD model, this study obtained pedestrian dynamics parameters from measured data of the properties of both empty structures and structures with pedestrian occupancy. The parameters identification procedure involved individuals at four walking frequencies. Body frequency is positively correlated to the walking frequency, while a negative correlation is observed between the body damping ratio and the walking frequency. The test results further show a negative correlation between the pedestrian’s frequency and his/her weight, but no significant correlation exists between one’s damping ratio and weight. The findings provide a reference for structural vibration serviceability assessments that would consider pedestrian–structure interaction effects.

scholarly journals Multi-Scale Study of The Small-Strain Damping Ratio of Fiber-Sand Composites

Polymers ◽  
2021 ◽  
Vol 13 (15) ◽  
pp. 2476
Author(s):  
Haiwen Li ◽  
Sathwik S. Kasyap ◽  
Kostas Senetakis
Keyword(s):  
Dynamic Properties ◽  
Wide Spectrum ◽  
Damping Ratio ◽  
Polypropylene Fiber ◽  
Small Strain ◽  
Treatment Method ◽  
Fiber Content ◽  
Polypropylene Fibers ◽  
Test Results ◽  
Fiber Reinforced

The use of polypropylene fibers as a geosynthetic in infrastructures is a promising ground treatment method with applications in the enhancement of the bearing capacity of foundations, slope rehabilitation, strengthening of backfills, as well as the improvement of the seismic behavior of geo-systems. Despite the large number of studies published in the literature investigating the properties of fiber-reinforced soils, less attention has been given in the evaluation of the dynamic properties of these composites, especially in examining damping characteristics and the influence of fiber inclusion and content. In the present study, the effect of polypropylene fiber inclusion on the small-strain damping ratio of sands with different gradations and various particle shapes was investigated through resonant column (macroscopic) experiments. The macroscopic test results suggested that the damping ratio of the mixtures tended to increase with increasing fiber content. Accordingly, a new expression was proposed which considers the influence of fiber content in the estimation of the small-strain damping of polypropylene fiber-sand mixtures and it can be complementary of damping modeling from small-to-medium strains based on previously developed expressions in the regime of medium strains. Additional insights were attempted to be obtained on the energy dissipation and contribution of fibers of these composite materials by performing grain-scale tests which further supported the macroscopic experimental test results. It was also attempted to interpret, based on the grain-scale tests results, the influence of fiber inclusion in a wide spectrum of properties for fiber-reinforced sands providing some general inferences on the contribution of polypropylene fibers on the constitutive behavior of granular materials.

scholarly journals Effect of Grain Refinement on the Dynamic, Mechanical Properties, and Corrosion Behaviour of Al-Mg Alloy

Metals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1825
Author(s):  
Haitham M. Ahmed ◽  
Hussin A. M. Ahmed ◽  
Mohammed Hefni ◽  
Essam B. Moustafa
Keyword(s):  
Mechanical Properties ◽  
Grain Refinement ◽  
Corrosion Behaviour ◽  
Cast Alloy ◽  
Dynamic Properties ◽  
Damping Ratio ◽  
Xrd Analysis ◽  
Optical Microscope ◽  
Mg Alloy ◽  
Resonance Frequencies

In this investigation, aluminium Al-2.5% Mg cast alloy was modified by adding 0.5 Ti and 0.1 B wt % modifiers to investigate their impact on the dynamic behaviour, as well as the mechanical and microstructure properties. The dynamic properties were analysed experimentally using a free vibration impact test and predicted using finite element methods. This study used a high-resolution polarised optical microscope to analyse the microstructure of the studied alloys and X-ray Powder Diffraction (XRD) analysis to determine the developed phases. Microstructure and mechanical properties were mostly enhanced as a result of grain refining during solidification and through the metal segregation process. The microstructure analysis of the modified alloy showed a significant improvement in the grain refinement; hence, the grains were 10 times finer than the cast alloy. The modified Al-2.5% Mg/Ti-B alloy demonstrated reduced inter-granular corrosion (IGC) than the Al-2.5% Mg standard cast alloy. By incorporating Ti-B modifiers into the composition of the cast Al-Mg alloy, the ultimate tensile strength (UTS), strain (ε), and hardness values (HV) were increased by 30.5%, 100%, and 18.18%, respectively. The dynamic properties of the modified alloy showed an enhancement in the resonant (fn) and damping ratio (ζ) by 7% and 68%, respectively. The predicted resonance frequencies of the investigated alloys showed results close to the experimental dynamic tests.

A Study on Dynamic Properties of Cement-Stabilized Soils

2011 ◽  
Vol 243-249 ◽  
pp. 2050-2054 ◽  
Author(s):  
Pei Hsun Tsai ◽  
Sheng Huoo Ni
Keyword(s):  
Shear Modulus ◽  
Dynamic Properties ◽  
Damping Ratio ◽  
Confining Pressure ◽  
Test Results ◽  
Resonant Column Test ◽  
Stabilized Soil ◽  
Shearing Strain ◽  
Relationship Of ◽  
The Relationship

In this paper the dynamic property (shear modulus and damping ratio) of cement-stabilized soil is studied with using the resonant column test. The amount of cement admixed, the magnitude of confining pressure, and shearing strain amplitude are the parameters considered. Test results show that the maximum shear modulus of cement-stabilized soil increases with increasing confining pressure, the minimum damping ratio decreases with increasing confining pressure. The shear modulus of cement-stabilized soil decreases with increasing shearing strain while the damping ratio increases with increasing shearing strain. In the paper the relationship of shear modulus versus shearing strain is fitted into the Ramberg-Osgood equations using regression analysis.

scholarly journals Characterization of the Dynamic Properties of Clay–Gravel Mixtures at Low Strain Level

2020 ◽  
Vol 12 (4) ◽  
pp. 1616 ◽  
Author(s):  
Xianwen Huang ◽  
Aizhao Zhou ◽  
Wei Wang ◽  
Pengming Jiang
Keyword(s):  
Shear Modulus ◽  
Shear Strain ◽  
Mechanical Performance ◽  
Dynamic Properties ◽  
Damping Ratio ◽  
Confining Pressure ◽  
Strain Level ◽  
Dynamic Shear Modulus ◽  
Dynamic Shear ◽  
Gravel Content

In order to support the dynamic design of subgrade filling engineering, an experiment on the dynamic shear modulus (G) and damping ratio (D) of clay–gravel mixtures (CGMs) was carried out. Forty-two groups of resonant column tests were conducted to explore the effects of gravel content (0%, 10%, 20%, 30%, 40%, 50%, and 60%, which was the mass ratio of gravel to clay), gravel shape (round and angular gravels), and confining pressure (100, 200, and 300 kPa) on the dynamic shear modulus, and damping ratio of CGMs under the same compacting power. The test results showed that, with the increase of gravel content, the maximum dynamic shear modulus of CGMs increases, the referent shear strain increases linearly, and the minimum and maximum damping ratios decrease gradually. In CGMs with round gravels, the maximum dynamic shear modulus and the maximum damping ratio are greater, and the referent shear strain and the minimum damping ratio are smaller, compared to those with angular gravels. With the increase of confining pressure, the maximum dynamic shear modulus and the referent shear strain increase nonlinearly, while the minimum and maximum damping ratios decrease nonlinearly. The predicting equation for the dynamic shear modulus and the damping ratio of CGMs when considering confining pressure, gravel content, and shape was established. The results of this research may put forward a solid foundation for engineering design considering low-strain-level mechanical performance.

Shear modulus reduction and damping ratio curves for earth core materials of dams

2019 ◽  
Vol 56 (1) ◽  
pp. 14-22 ◽  
Author(s):  
DongSoon Park ◽  
Tadahiro Kishida
Keyword(s):  
Shear Modulus ◽  
Dynamic Properties ◽  
Damping Ratio ◽  
Empirical Relationship ◽  
Embankment Dams ◽  
In Situ Data ◽  
Earth Core ◽  
Dynamic Analyses ◽  
Modulus Reduction ◽  
Core Materials

It is essential to obtain shear modulus reduction and damping ratio curves to perform dynamic analyses of earth-cored embankment dams. Many studies have been performed for dynamic properties of clayey soils, but they have been limited for earth core materials of dams. This study conducted resonant column tests to obtain shear modulus reduction (G/Gmax) and damping ratio (D) curves for 31 specimens (17 undisturbed and 14 remolded specimens) from 13 earth-cored embankment dams. Empirical G/Gmax and D curves are proposed for dynamic properties of clayey earth core materials. Fitting curves are provided by using the functional forms of the Ramberg–Osgood and Darendeli models. The observation shows that the undisturbed earth cores yield relatively higher G/Gmax and lower D curves than the remolded cores. G/Gmax curves of compacted earth cores are relatively higher than those of Vucetic and Dobry curves for a similar level of plasticity index. Uncertainty and bias are calculated by performing residual analysis, which shows that there is no clear bias in predicting G/Gmax and the uncertainties between undisturbed earth core materials and natural deposits are at a similar level. A proposed empirical relationship of G/Gmax and D curves for earth core materials can be utilized for dynamic analyses of embankment dams for cases where there is insufficient in situ data.

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