A Novel Nondestructive Procedure for Tire Tread Viscoelastic Characterization

2021 ◽  
Author(s):  
A. Genovese ◽  
S. R. Pastore
Keyword(s):  
Vehicle Dynamics ◽  
Testing Procedure ◽  
Portable Instrument ◽  
Instrumented Indentation ◽  
Processing Procedure ◽  
Application Fields ◽  
Stiffness And Damping ◽  
Great Portion ◽  
Time Assessment

ABSTRACT Vehicle dynamics is largely influenced by the phenomena occurring in the tire-road interface, and a great portion of these phenomena is mainly conditioned by the viscoelastic properties of the tire tread compound. It is not surprising that the possibility of obtaining the viscoelastic response of a compound by means of a nondestructive procedure is a growing research topic that affects application fields ranging from monitoring of the material performance during its entire life cycle to the quantitative analysis of product quality and repeatability of production processes. In this article, a novel nondestructive procedure for the viscoelastic characterization of tire tread compound is proposed. A portable instrument, based on instrumented indentation, was designed and prototyped with the aim to allow a real-time assessment of moduli directly on site. The testing procedure adopted to perform the test on three different compounds was described. A signal-processing procedure was developed for the identification of compound stiffness and damping parameters from which viscoelastic moduli were estimated. The results were also compared with the DMA characterization showing the same relative ranking between the compounds with a different trend in temperature due to the amount of the tests' indentation depth.

Characteristics in Response Integration and Bifurcation of a Forced Duffing Oscillator

2007 ◽  
Author(s):  
Jang-Der Jeng ◽  
Yuan Kang ◽  
Yeon-Pun Chang ◽  
Shyh-Shyong Shyr
Keyword(s):  
Applied Sciences ◽  
Phase Plane ◽  
Duffing Oscillator ◽  
High Order ◽  
Chaotic Motions ◽  
Integration Algorithm ◽  
High Order Harmonic ◽  
Stiffness And Damping

The Duffing oscillator is well-known models of nonlinear system, with applications in many fields of applied sciences and engineering. In this paper, a response integration algorithm is proposed to analyze high-order harmonic and chaotic motions in this oscillator for modeling rotor excitations. This method numerically integrates the distance between state trajectory and the origin in the phase plane during a specific period and predicted intervals with excitation periods. It provides a quantitative characterization of system responses and can replace the role of the traditional stroboscopic technique (Poincare´ section method) to observe bifurcations and chaos of the nonlinear oscillators. Due to the signal response contamination of system, thus it is difficult to identify the high-order responses of the subharmonic motion because of the sampling points on Poincare´ map too near each other. Even the system responses will be made misjudgments. Combining the capability of precisely identifying period and constructing bifurcation diagrams, the advantages of the proposed response integration method are shown by case studies. Applying this method, the effects of the change in the stiffness and the damping coefficients on the vibration features of a Duffing oscillator are investigated in this paper. From simulation results, it is concluded that the stiffness and damping of the system can effectively suppress chaotic vibration and reduce vibration amplitude.

Modeling and Identification of Elastomeric Bearing Characteristics for Large-Scale Simulations

1998 ◽  
Vol 120 (1) ◽  
pp. 63-73 ◽  
Author(s):  
K. N. Morman ◽  
E. Nikolaidis ◽  
J. Rakowska ◽  
S. Seth
Keyword(s):  
Large Scale ◽  
Dynamic Stiffness ◽  
Testing Procedure ◽  
Nonlinear Dependence ◽  
Model Parameters ◽  
Elastomeric Bearing ◽  
Nonlinear Viscoelastic ◽  
Component Test ◽  
Differential Type ◽  
Stiffness And Damping

A constitutive equation of the differential type is introduced to model the nonlinear viscoelastic response behavior of elastomeric bearings in large-scale system simulations for vibration assessment and component loads prediction. The model accounts for the nonlinear dependence of dynamic stiffness and damping on vibration amplitude commonly observed in the behavior of bearings made of particle-reinforced elastomers. A testing procedure for the identification of the model parameters from bearing component test data is described. The experimental and analytical results for predicting the behavior of four (4) different car bushings are presented. In an example application, the model is incorporated in an ADAMS simulation to study the dynamic behavior of a car rear suspension.

Rotordynamic characterization of tilting-pad bearings with eight pads in vertical rotors

2021 ◽  
pp. 1-20
Author(s):  
David J Rondon ◽  
Gudeta Berhanu Benti ◽  
Jan-Olov Aidanpää ◽  
Rolf Gustavsson
Keyword(s):  
Stokes Equations ◽  
Forced Response ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Mean Values ◽  
Stationary Coordinate System ◽  
Tilting Pad ◽  
Tilting Pad Bearings ◽  
Stiffness And Damping

Abstract It has been documented that stiffness and damping for a four-pad bearing are dependent not only the magnitude of the load but also on the position of the rotor in the bearing. However, 8-pad bearings are not commonly employed on horizontal turbines, and the presence of several pads in the bearing will decisively affect the dynamics of the system. This paper evaluates the stiffness and damping coefficients of tilting-pad bearings with eight pads and explore the main frequencies acting on the forced response of a vertical rotor. The bearing properties were modeled as a function of eccentricity and position in the stationary coordinate system by Navier-Stokes equations whose results are taken from commercial software. The simulated unbalanced response is compared to experimental results; the changing position of the shaft produces a periodic stiffness and damping, which is dependent on the number of pads. Cross-coupled coefficients influence is discussed, showing that their absence makes an accurate model for the mean values. The results indicate that simulation of vertical rotors with 8-pad bearings can be simplified which allow more effective simulations and dynamic analysis.

Characterization of Anisotropy of Strength in API-X80 Line Pipe Welds Through Instrumented Indentation

2020 ◽  
Vol 9 (6) ◽  
pp. 884-894
Author(s):  
A. R. H. Midawi ◽  
N. Huda ◽  
C. H. M. Simha ◽  
A. P. Gerlich
Keyword(s):  
Instrumented Indentation ◽  
Line Pipe

scholarly journals Novel Benchtop Magnetic Particle Spectrometer for Process Monitoring of Magnetic Nanoparticle Synthesis

Nanomaterials ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 2277
Author(s):  
Norbert Löwa ◽  
Dirk Gutkelch ◽  
Ernst-Albrecht Welge ◽  
Roland Welz ◽  
Florian Meier ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Magnetic Nanoparticles ◽  
Process Monitoring ◽  
Magnetic Nanoparticle ◽  
Magnetic Particle ◽  
Nanoparticle Synthesis ◽  
Separation Processes ◽  
Magnetic Detector ◽  
Application Fields

Magnetic nanoparticles combine unique magnetic properties that can be used in a variety of biomedical applications for therapy and diagnostics. These applications place high demands on the magnetic properties of nanoparticles. Thus, research, development, and quality assurance of magnetic nanoparticles requires powerful analytical methods that are capable of detecting relevant structural and, above all, magnetic parameters. By directly coupling nanoparticle synthesis with magnetic detectors, relevant nanoparticle properties can be obtained and evaluated, and adjustments can be made to the manufacturing process in real time. This work presents a sensitive and fast magnetic detector for online characterization of magnetic nanoparticles during their continuous micromixer synthesis. The detector is based on the measurement of the nonlinear dynamic magnetic response of magnetic nanoparticles exposed to an oscillating excitation at a frequency of 25 kHz, a technique also known as magnetic particle spectroscopy. Our results underline the excellent suitability of the developed magnetic online detection for coupling with magnetic nanoparticle synthesis based on the micromixer approach. The proven practicability and reliability of the detector for process monitoring forms the basis for further application fields, e.g., as a monitoring tool for chromatographic separation processes.

Expedited Testing Program for Performance Characterization of Asphalt Mixtures

2019 ◽  
Vol 2673 (12) ◽  
pp. 225-233
Author(s):  
Intikhab Haidar ◽  
Charles W. Schwartz ◽  
Sadaf Khosravifar
Keyword(s):  
Permanent Deformation ◽  
Performance Testing ◽  
Testing Procedure ◽  
Test Methods ◽  
Asphalt Mixtures ◽  
Test Specifications ◽  
Research Grade ◽  
Repeated Load ◽  
Lengthy Process

The past two decades have seen significant efforts to standardize a series of simplified test methods to characterize the dynamic modulus (DM) and repeated load permanent deformation (RLPD) performance characteristics of asphalt mixtures using the asphalt mixtures performance tester (AMPT). While the current AASHTO T 79 test specifications for the AMPT are faster and easier to perform than their preceding research grade test protocols, there is still reluctance among highway agencies and industry to conduct performance testing using the AMPT. One significant reason is the lengthy process of sample preparation and testing for the DM and RLPD tests. Two studies to expedite this process are reported here. First, the potential for abbreviating the DM testing procedure was examined. It provides the option to fully exclude testing at 40°C by adding an additional frequency of 0.01 Hz at 20°C. This approach reduces time for testing as well as for sample conditioning at high temperature. Second, the possibility of reducing the total number of required specimens was evaluated. The variation of the DM under repetitive testing and the appropriateness of performing the RLPD test on samples already tested for DM were evaluated. The results showed that specimen damage or densification because of DM testing is insignificant. As a consequence, DM test specimens can be re-used for RLPD testing, reducing the required number of samples from 12 to 9.

Microstructural Characterization of Ornamental Rock Samples: Cariri Rocks

2016 ◽  
Vol 869 ◽  
pp. 159-163
Author(s):  
Danúbia Lisbôa da Costa ◽  
Ingrid Mayara Medeiros Fernandes ◽  
Aluska Nascimento Simões Braga ◽  
Rosiane Maria da Costa Farias ◽  
Romualdo Rodrigues Menezes ◽  
...  
Keyword(s):  
Chemical Analysis ◽  
Microstructural Characterization ◽  
Magnesium Carbonate ◽  
X Ray Diffraction ◽  
X Ray ◽  
Mineral Sector ◽  
Microstructural Heterogeneity ◽  
Calcium And Magnesium ◽  
Application Fields

Ornamental rocks are among the most promising business areas of the mineral sector, raising the necessity for, besides beauty, investments in quality, safety and characterization in the various application fields of these rocks. So, this work aims at the microstructural characterization of the class of these rocks: the Cariri Rocks, also known the limestone, which are calcareous rocks mainly formed by calcium and magnesium carbonate, possibly presenting variations due to their origins. For characterization, we studied four samples, being two from Chapada do Apodi and two from Chapada do Araripe, characterized physically and micro-structurally through chemical analysis, X-ray diffraction, optical micrography and porosimetry tests. The results prove that the limestones are calcitic and dolomitic, and present porosity varying from 5 to 15%, with pores concentration between 100nm and 10μm, besides the high microstructural heterogeneity.

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