Determination of dynamic properties of flax fibres reinforced laminate using vibration measurements

2017 ◽  
Vol 57 ◽  
pp. 219-225 ◽  
Author(s):  
A. El-Hafidi ◽  
P.B. Gning ◽  
B. Piezel ◽  
M. Belaïd ◽  
S. Fontaine
Keyword(s):  
Dynamic Properties ◽  
Vibration Measurements ◽  
Flax Fibres

Experimental evaluation of a test base for ship engines

1995 ◽  
Vol 32 (6) ◽  
pp. 1048-1059
Author(s):  
Francisco de Rezende Lopes ◽  
Mariza Gomes Ribeiro
Keyword(s):  
Key Words ◽  
Experimental Evaluation ◽  
Dynamic Properties ◽  
Heavy Industry ◽  
Foundation Soil ◽  
Vibration Measurements ◽  
Resonant Frequencies ◽  
Test Base

During the test and running-in of some ship engines in a heavy industry, severe vibrations, of a magnitude that impeded precision work in other areas of the industry, were observed. Vibration measurements were carried out during the test of an engine that confirmed previous suspicions that resonance occurred during the test of some engine models. These measurements led to the determination of dynamic properties of the foundation soil, which allowed the computation of the resonant frequencies of other engine models, so as to avoid these frequencies during their tests. Key words : dynamics, foundations, instrumentation, analysis.

Automation of selected brazes' dynamic properties in high-temperatures' measurement process

2013 ◽  
Vol 18 (2-3) ◽  
pp. 33-41
Author(s):  
Dominik Sankowski ◽  
Marcin Bakala ◽  
Rafał Wojciechowski
Keyword(s):  
Surface Tension ◽  
High Temperatures ◽  
Dynamic Properties ◽  
Automatic Measurement ◽  
Measurement Methodology ◽  
Joining Process ◽  
Wetting Force ◽  
Research Grant

Abstract The good quality of several manufactured components frequently depends on solidliquid interactions existing during processing. Nowadays, the research in material engineering focuses also on modern, automatic measurement methods of joining process properties, i.a. wetting force and surface tension, which allows for quantitative determination of above mentioned parameters. In the paper, the brazes’ dynamic properties in high-temperatures’ measurement methodology and the stand for automatic determination of braze’s properties, constructed and implmented within the research grant nr KBN N N519 441 839 - An integrated platform for automatic measurement of wettability and surface tension of solders at high temperatures, are widely described

Applications of Thermal Analytical Procedures in the Study of Elastomers and Elastomer Systems

1980 ◽  
Vol 53 (3) ◽  
pp. 437-511 ◽  
Author(s):  
D. W. Brazier
Keyword(s):  
Thermal Analysis ◽  
Dynamic Properties ◽  
Evolved Gas Analysis ◽  
Gas Analysis ◽  
International Standards ◽  
New Technique ◽  
Heating Rates ◽  
Single Experiment ◽  
Rubber Compounds

Abstract An attempt has been made to review the development of thermoanalytical procedures as they have been applied to elastomers and elastomer systems over the past 10 years. For all rubber industry products, temperature and its effects, either alone or in conjunction with the chemical environment, play an important role from the production stage through to the final failure of the product in the field. It is thus not surprising that thermal analysis, in which temperature is the prime variable, has found such diverse applications in elastomer studies. The identification and quantitative analysis of rubber formulations have received most attention. Such formulations produce characteristic “fingerprints” when studied in DTA, DSC, TG, or TMA. In DSC, the determination of the glass transition characteristics, the observation and determination of crystallinity, the detection of cyclization reactions, and the monitoring of thermal and oxidative degradation characteristics can all be observed in a single experiment covering the temperature range from −150 to +600°C. At normal heating rates, e.g., 20°C/min, such information is available in 40 min. TG/DTG analysis can yield the elastomer or elastomers content, oil and plasticizer, carbon black (level and often type), and inorganic ash in less than 60 min. Processing and curing can also be studied. Blend compatibility can be assessed on the basis of both Tg and crystallinity measurements and the data used to determine optimum mixing times. Sulfur vulcanization and peroxide curing of elastomers is readily monitored by DSC and can be used for confirmation analysis of the presence of curatives. Limitations in such analysis exist, but as understanding and ability to interpret cure exotherms increase, valuable information about the mechanism and the nature of the cured network will be obtained. The testing of rubber compounds involves many hours of labor by current procedures. The rapidity of thermal analysis promises to offer some relief. In addition to DSC and TG, TMA, a relatively new technique, offers a rapid approach to low-temperature testing. Dynamic mechanical analysis (DMA) offers a rapid route to determining dynamic properties, but as yet, relatively little has been published on the application of this new technique to elastomers. As environmental concern increases, techniques such as evolved gas analysis (EGA) and combined techniques such as TG/gas chromatography are predicted to play an important role. As for the future, it is readily apparent that the principles of the methods have been established and, in several cases, it now remains to reduce them to a practical level. In some areas, such as vulcanization studies, much remains to be undertaken to improve our interpretive skills. Although there is some indication that certain industries have produced “in-house” standards for the analysis of rubber compounds by DSC and TG/DTG, it will only be when national and international standards organizations study and produce standard procedures, that the techniques will be generally adopted. Maurer's prediction in 1969 of increased applications of DTA and TG in elastomer studies has undoubtedly proved correct, and with the proliferation of reliable commercial instrumentation, significant developments can be anticipated in the next decade.

Managing Flow Induced Vibration in Subsea Jumpers

2021 ◽  
Author(s):  
Rakshith Naik ◽  
Yetzirah Urthaler ◽  
Scot McNeill ◽  
Rafik Boubenider
Keyword(s):  
Dynamic Properties ◽  
Fatigue Analysis ◽  
Management Program ◽  
Measured Data ◽  
Operating Conditions ◽  
Valuable Insight ◽  
Fe Model ◽  
Flow Induced Vibration ◽  
Vibration Measurements

Abstract Certain subsea jumper design features coupled with operating conditions can lead to Flow Induced Vibration (FIV) of subsea jumpers. Excessive FIV can result in accumulation of allowable fatigue damage prior to the end of jumper service life. For this reason, an extensive FIV management program was instated for a large development in the Gulf of Mexico (GOM) where FIV had been observed. The program consisted of in-situ measurement, modeling and analysis. Selected well and flowline jumpers were outfitted with subsea instrumentation for dedicated vibration testing. Finite Element (FE) models were developed for each jumper and refined to match the dynamic properties extracted from the measured data. Fatigue analysis was then carried out using the refined FE model and measured response data. If warranted by the analysis results, action was taken to mitigate the deleterious effects of FIV. Details on modeling and data analysis were published in [5]. Herein, we focus on the overall findings and lessons learned over the duration of the program. The following topics from the program are discussed in detail: 1. In-situ vibration measurement 2. Overall vibration trends with flow rate and lack of correlation of FIV to flow intensity (rho-v-squared); 3. Vibration and fatigue performance of flowline jumpers vs. well jumpers 4. Fatigue analysis conservatism Reliance on screening calculations or predictive FE analysis could lead to overly conservative operational limits or a high degree of fatigue life uncertainty in conditions vulnerable to FIV. It is proposed that in-situ vibration measurements followed by analysis of the measured data in alignment with operating conditions is the best practice to obtain a realistic understanding of subsea jumper integrity to ensure safe and reliable operation of the subsea system. The findings from the FIV management program provide valuable insight for the subsea industry, particularly in the areas of integrity management of in-service subsea jumpers; in-situ instrumentation and vibration measurements and limitations associated with predictive analysis of jumper FIV. If learnings, such as those discussed here, are fed back into design, analysis and monitoring guidelines for subsea equipment, the understanding and management of FIV could be dramatically enhanced compared to the current industry practice.

scholarly journals Determination of the Vibration Within a Squeeze-Film Damper Under Rotational Unbalance Conditions From Externally Mounted Sensors

2019 ◽  
Author(s):  
Ghaith Ghanim Al-Ghazal ◽  
Philip Bonello ◽  
Sergio G. Torres Cedillo
Keyword(s):  
Nonlinear Response ◽  
Squeeze Film ◽  
Training Procedure ◽  
Vibration Measurements ◽  
Squeeze Film Damper ◽  
Identification Process ◽  
Operational Conditions ◽  
Validation Tests ◽  
Future Work

Abstract Recently, there has been a focus on the use of inverse problem techniques in order to monitor rotor unbalance, and obtain a balancing solution, from vibration measurements on the casing and prior knowledge of the rotor-casing structure. In certain practical configurations that use nonlinear bearings like the squeeze-film damper (SFD) bearing, an inverse model of the bearing is an important part of the unbalance identification process. The inverse bearing model is used to estimate the journal vibration from casing vibration measurements, thus acting as a substitute for internal instrumentation in applications where the rotor is not accessible under operational conditions. Previous research has shown that an inverse bearing model can be identified using a trained Recurrent Neural Network (RNN) from experimental input/output data. However, the RNN was both trained and validated under simulated rotational conditions, wherein the motion was driven by two orthogonally-phased perpendicular shakers. In this paper, a RNN of an inverse bearing model that is identified from experimental data generated under simulated rotational conditions is validated under actual rotational (i.e. unbalance-driven) vibration conditions. The necessary modifications to the test rig are presented, together with the identification/training procedure. The results of the validation tests show that the RNN is capable of predicting the frequency spectrum of the dynamic nonlinear response of the journal with reasonable accuracy. This inverse SFD bearing model can be thus used in a future work to identify rotor unbalance.

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