scholarly journals Enhancing Vibration Reduction on Lightweight Lower Control Arm

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Alessandro Messana ◽  
Alessandro Ferraris ◽  
Andrea G. Airale ◽  
Alessandro Fasana ◽  
Massimiliana Carello
Keyword(s):  
Mechanical Performance ◽  
Dynamic Properties ◽  
Damping Ratio ◽  
Vibration Reduction ◽  
Design Procedure ◽  
Test Results ◽  
Hybrid Lca ◽  
Original Solution ◽  
Lower Control Arm ◽  
Real Behavior

This paper describes the design procedure to enhance the damping properties of a multimaterial lightweight suspension arm for a C-segment vehicle. An innovative viscoelastic material has been used to join carbon fiber with steel that has a function of passive constrained layer damper and adhesive simultaneously. Therefore, the hybrid technology applied has been focused on reducing the LCA mass, diminishing the steel thickness, and adding a CFRP tailored cover without compromising the global mechanical performance. Particular attention has been paid to the investigation of the dynamic response in terms of vibration reduction, especially in the range of structure-borne frequencies of 0–600 Hz. Two different viscoelastic materials have been evaluated in such a way to compare their stiffness, damping, and dynamic properties. The experimental test results have been virtually correlated with a commercial FEM code to create the respective material card and predict the real behavior of the LCAs (original and hybrid). The experimental modal analysis has been performed and compared on both the arms highlighting a very good correlation between virtual and experimental results. In particular, the hybrid LCA allows an interesting improvement of damping ratio, about 3,5 times higher for each eigenmode than in the original solution.

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.

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.

Vibration reduction of a flexible robot link using a frictional damper

2020 ◽  
pp. 107754632093609
Author(s):  
Hamed Biglari ◽  
Masoud Golmohammadi ◽  
Sajad Hayati ◽  
Siroos Hemmati
Keyword(s):  
Damping Ratio ◽  
Vibration Reduction ◽  
Flexible Manipulator ◽  
Test Results ◽  
The Finite Element Method ◽  
Flexible Robot ◽  
Nsga Ii ◽  
Modal Test ◽  
Realistic Situation ◽  
Euler Bernoulli Beam

One of the most important factors reducing flexible manipulator efficiency is the residual vibration occurrence. In this research, vibration reduction of flexible manipulators is investigated using an internal frictional damper. At first, the vibration equation of a manipulator is obtained using the finite element method with the Euler–Bernoulli beam element to study its vibrations in a reciprocal motion. In addition, an analytical model is developed to investigate the effect of the frictional damper on robot link vibrations. Using particle swam optimization, ICA, NSGA-II, and GWO methods, the optimal structure for the damper is obtained to maximize its effect. The optimally damped link is fabricated, and its dynamic characteristics are extracted from a modal test experiment. The modal test results show a considerable improvement in the damping ratio of the damped link in comparison with a simple link. The fabricated link samples are then tested in a realistic situation. The experimental results are in coincidence with the simulation results, certifying the performance of the proposed plan in vibration reduction of a robot link.

scholarly journals Mechanical and Damping Properties of Recycled Aggregate Concrete Modified with Air-Entraining Agent and Polypropylene Fiber

Materials ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 2004 ◽  
Author(s):  
Chonggang Zhou ◽  
Xingwang Pei ◽  
Wenlong Li ◽  
Yijun Liu
Keyword(s):  
Mechanical Performance ◽  
Dynamic Properties ◽  
Damping Ratio ◽  
Polypropylene Fiber ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Favorable Effect ◽  
Damping Properties ◽  
Aggregate Concrete ◽  
Negative Effect

In this study, recycled aggregate concrete (RAC) modified with polypropylene fiber (PP) and air-entraining agent (AGA) was prepared, and the effects of PP and AGA on the static (compressive strength, Young’s modulus, and splitting tensile strength) and dynamic properties (dynamic modulus of elasticity and damping ratio) of RAC were investigated. The experimental results showed that the addition of an AGA and PP had a favorable effect on the damping ratio of the concrete, however, the addition of the AGA had a slightly negative effect on the mechanical performance of the concrete. The AGA and PP contents required to achieve the optimum damping ratio of the concrete with the least reduction in the mechanical performance were 0.02% and 0.10%, respectively. Furthermore, the addition of AGA was more effective than that of PP in improving the damping property of the concrete.

Experimental Study on Lateral Stiffness and Dynamic Properties of Steel Drive-in Storage Racks

2013 ◽  
Vol 351-352 ◽  
pp. 730-733
Author(s):  
Bo Cheng ◽  
Zhen Yu Wu
Keyword(s):  
Load Transfer ◽  
Dynamic Properties ◽  
Damping Ratio ◽  
Single Point ◽  
Lateral Stiffness ◽  
Test Results ◽  
Static Test ◽  
Vibration Tests ◽  
Storage Racks ◽  
Deformation Modes

The static and free vibration tests were carried out to investigate the initial lateral stiffness and dynamic properties of steel drive-in storage racks. The bracing configuration and friction between pallets and rail beams were taken into consideration. The static test results indicate that the tested storage racks show sideways and torsional deformation modes under the single-point horizontal force. Both top plan bracings and back spine bracings can change the load transfer through the rack framework, strengthen the initial lateral stiffness of racks, but only back spine bracings can affect the natural frequency and damping ratio of racks. The friction force between pallets and rail beams makes pallets act as links to connect adjacent rack columns, so the pallets are beneficial factors to increase the lateral stiffness of storage racks. Compared with unload racks, the natural frequencies of loaded racks are smaller.

ANALYSIS OF DYNAMIC STRESS-STRAIN RELATIONSHIP OF LOESS

2008 ◽  
Vol 22 (31n32) ◽  
pp. 5559-5565
Author(s):  
HONGJIAN LIAO ◽  
ZHIGANG ZHANG ◽  
CHUNMING NING ◽  
JIAN LIU ◽  
LI SONG
Keyword(s):  
Residual Strain ◽  
Dynamic Stress ◽  
Dynamic Properties ◽  
Damping Ratio ◽  
Constitutive Relationship ◽  
Triaxial Tests ◽  
Stress And Strain ◽  
Test Results ◽  
Relationship Model ◽  
Strain Relationship

This paper aims to study dynamic properties of loess. This study is helpful to the subject on how to avoid or decrease the seismic disasters on loess ground. Dynamic triaxial tests are carried out with saturated remoulded soil samples taken form loess sites in Xi'an, China. Dynamic stress and strain relationship as well as the rule of the accumulated residual strain are obtained from the test results. Linear relationship between accumulated residual strain and vibration circle under constant amplitude circular loading is presented. A hypothesis about the accumulated residual strain is proposed. 1D dynamic constitutive relationship model which can well describe the real relationship between dynamic stress and strain under irregular dynamic loading is established. Numerical program with this model is developed and an example is tested. Numerical results of hysteresis loop, accumulated residual strain, amplitude of dynamic stress and damping ratio show good agreement with test results. It is indicated that the hypothesis of accumulated residual strain and the 1D dynamic constitutive relationship model can accurately simulate the dynamic triaxial tests of saturated remoulded loess.

scholarly journals Empirical Method for Evaluating Resilient Modulus of Saturated Silty Clay under Cyclic Loading

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Zhen Zhang ◽  
Yong Chen ◽  
Guanbao Ye ◽  
Peilin Xiang ◽  
Yan Xiao ◽  
...  
Keyword(s):  
Cyclic Loading ◽  
Stress Ratio ◽  
Resilient Modulus ◽  
Dynamic Properties ◽  
Damping Ratio ◽  
Empirical Method ◽  
Traffic Load ◽  
Triaxial Tests ◽  
Silty Clay ◽  
Test Results

Resilient modulus of soil is crucial for the design of a structure on a foundation subjected to a cyclic loading (e.g., traffic load or machine vibration load). This paper conducted a series of dynamic triaxial tests of saturated silty clay, considering the influence of the factors of cyclic stress ratio (CSR), static deviatoric stress ratio (SDR), and overconsolidation ratio (OCR) on the resilient modulus and dynamic damping ratio of the soil. A cyclic loading with a form of half sine wave was used to model the traffic loading. The results showed that the soil was prone to failure under a higher SDR, even though the applied CSR was less than the critical CSR. The saturated silty clay performed a strain softening behavior and its dynamic properties deteriorated significantly when higher CSR and SDR and lower OCR were involved. Based on the test results, an empirical method with a form of exponential function was proposed to evaluate the resilient modulus of the soil, considering the combined effects of CSR and SDR and OCR. The proposed method was verified through a comparison with the test results in this study and from literatures, and some recommendations for its application were offered.

scholarly journals Comparison between Ramberg-Osgood and Hardin-Drnevich soil models in Midas GTS NX

2021 ◽  
Author(s):  
Majd Ahmad ◽  
Richard Ray
Keyword(s):  
Dynamic Properties ◽  
Damping Ratio ◽  
Dynamic Shear Modulus ◽  
Resonant Column ◽  
Test Results ◽  
Material Models ◽  
Simple Shear Test ◽  
Finite Element Software ◽  
Loading Patterns ◽  
Irregular Loading

AbstractThis paper studies the two widely used material models for predicting the dynamic behavior of soils, the Ramberg-Osgood and Hadrin-Drnevich models. Resonant column and torsional simple shear test results on dry sand were used to calibrate and evaluate the model built in the finite element software Midas GTS NX. Both material models are already implemented by the software. This study estimates the ability and efficiency of both soil models coupled with the Masing criteria to predict the behavior of soil when subjected to irregular loading patterns, (e.g., earthquakes), and measure the two most important dynamic properties, the dynamic shear modulus, and the damping ratio.

scholarly journals Theoretical analysis and experimental research on multi-layer elastic damping track structure

2021 ◽  
Vol 13 (2) ◽  
pp. 168781402199497
Author(s):  
Guanghui Xu ◽  
Shengkai Su ◽  
Anbin Wang ◽  
Ruolin Hu
Keyword(s):  
Finite Element ◽  
Analytical Solution ◽  
Finite Element Simulation ◽  
Reaction Force ◽  
Vibration Reduction ◽  
Vertical Direction ◽  
Propagation Path ◽  
Track Structure ◽  
Test Results ◽  
Element Simulation

The increase of axle load and train speed would cause intense wheelrail interactions, and lead to potential vibration related problems in train operation. For the low-frequency vibration reduction of a track system, a multi-layer track structure was proposed and analyzed theoretically and experimentally. Firstly, the analytical solution was derived theoretically, and followed by a parametric analysis to verify the vibration reduction performance. Then, a finite element simulation is carried out to highlight the influence of the tuned slab damper. Finally, the vibration and noise tests are performed to verify the results of the analytical solution and finite element simulation. As the finite element simulation indicates, after installation of the tuned slab damper, the peak reaction force of the foundation can be reduced by 60%, and the peak value of the vertical vibration acceleration would decrease by 50%. The vibration test results show that the insertion losses for the total vibration levels are 13.3 dB in the vertical direction and 21.7 dB in the transverse direction. The noise test results show that the data of each measurement point is smoother and smaller, and the noise in the generating position and propagation path can be reduced by 1.9 dB–5.5 dB.

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