scholarly journals Characterising Modal Behaviour of a Cantilever Beam at Different Heating Rates for Isothermal Conditions

2021 ◽  
Vol 11 (10) ◽  
pp. 4375
Author(s):  
Khangamlung Kamei ◽  
Muhammad A. Khan ◽  
Kamran A. Khan
Keyword(s):  
Cantilever Beam ◽  
Structural Response ◽  
Effect Of Temperature ◽  
Slow Heating ◽  
Modal Parameters ◽  
Limited Information ◽  
Heating Rates ◽  
Isothermal Conditions ◽  
Modal Amplitude ◽  
Rate Of Heating

The effect of temperature on structural response is a concern in engineering applications. The literature has highlighted that applied temperature loads change the system vibration behaviour. However, there is limited information available about temperature impacting the dynamic response. This paper investigated the heating rates effects on modal parameters for both with crack and without crack conditions in a cantilever beam. A beam subjected to three heating rates was considered: 2, 5, and 8 °C/min. The first one was assumed as a slow heating rate while the others were assumed as moderate and high, respectively. This controlled rate of heating was achieved by using a proportional-integral-derivative (PID) temperature controller. The results showed that heating at different rates has little impact on modal parameters. While this effect is minimal at lower temperatures and more evident at higher temperatures. The results of temperature ramped at 2, 5, and 8 °C/min were compared with the numerical and analytical results only for all the isothermal conditions. It was observed that the beam natural frequency and its modal amplitude decrease with the increase in temperatures and crack depths. Therefore, it is concluded that the rate of heating can make a slight impact on the dynamics response of any mechanical system.

Influence of Rate of Heating to Aging Temperature on Precipitation Hardening in a Metastable β Titanium Alloy

2014 ◽  
Vol 1025-1026 ◽  
pp. 445-450 ◽  
Author(s):  
Ashwary Pande ◽  
Salil Sainis ◽  
Santhosh Rajaraman ◽  
Geetha Manivasagam ◽  
M. Nageswara Rao
Keyword(s):  
Mechanical Properties ◽  
Titanium Alloy ◽  
Heating Rate ◽  
Aging Temperature ◽  
Alpha Phase ◽  
Slow Heating ◽  
Precipitation Reaction ◽  
Heating Rates ◽  
Rate Of Heating ◽  
Reduction In Area

A comparison between slow heating to aging temperature and direct charging at aging temperature on the microstructure and mechanical properties obtained after the aging was established for the metastable beta (β) titanium alloy Ti-15V-3Cr-3Al-3Sn. The alloy was subjected to two single aging (SA) and two duplex aging (DA) conditions, with two heating rates to aging temperature: (i) low heating rate of 5 oC/min (ii) direct charging into a furnace heated to aging temperature. The microstructure analysis was carried out using Field Emission Scanning Electron Microscopy. Mechanical Testing was carried to evaluate Ultimate Tensile Strength (UTS), 0.2% Yield Strength (YS), % Elongation (%El.), % Reduction in area (%RA) and hardness. In the case of SA samples aged at 500 °C for 8 h and 500 °C for 10 h, heating rate of 5 °C/min to aging temperature resulted in a finer microstructure but did not help in achieving better strength-ductility combination compared to direct charging. Lower rate of heating allows enough dwell time in the temperature range 250-300 oC for pre-precipitation reaction to occur which aids in fine scale precipitation of alpha phase during aging. In the case of DA samples aged at 250 oC for 24 h followed by 500 oC for 8 h and 300 oC for 10 h followed by 500 oC for 10 h, no tangible difference between lower rate of heating and direct charging was observed in mechanical properties or microstructure. This is believed to be due to the pre-aging steps 250 oC/24 h or 300 oC/10h in the two DA treatments, which create finely distributed precursors thereby leaving no scope for the heating rate to play a role.

scholarly journals Effect of Environmental Conditions on the Modal Response of a 10-Story Reinforced Concrete Tower

2018 ◽  
Vol 2018 ◽  
pp. 1-16 ◽  
Author(s):  
Marco Regni ◽  
Davide Arezzo ◽  
Sandro Carbonari ◽  
Fabrizio Gara ◽  
Daniele Zonta
Keyword(s):  
Reinforced Concrete ◽  
Wind Velocity ◽  
Natural Frequencies ◽  
Structural Response ◽  
Low Noise ◽  
Effect Of Temperature ◽  
Modal Parameters ◽  
Reinforced Concrete Frame ◽  
Torsional Mode ◽  
Concrete Frame

We analyse the effect of temperature and wind velocity on the natural frequencies and modal damping ratios of the Faculty of Engineering Tower at the Università Politecnica delle Marche, a 10-story reinforced concrete frame building, permanently monitored with low-noise accelerometers. The data recorded over the first 5 months of monitoring demonstrate that temperature variations and wind intensity have a clear effect on the first three natural frequencies and the corresponding damping ratios. Temperature is positively correlated to the first and second frequencies, corresponding to shear displacement modes and negatively correlated to the third frequency, corresponding to a torsional mode. All frequencies are positively correlated to wind velocity and changes in damping ratios are inversely correlated to any change in frequency. A mechanical explanation of these phenomena is offered, based on a critical review of literature case studies. These results suggest that using changes in modal parameters for damage detection always requires accurate knowledge of the correlation between modal parameters and environmental quantities (temperature, humidity, and wind velocity), an information which is only available through long-term continuous monitoring of the structural response.

scholarly journals Pyrolysis and Oxidation of PAN in Dry Air. Thermoanalytical Methods

1970 ◽  
Vol 17 (1) ◽  
pp. 38-42
Author(s):  
Anna BIEDUNKIEWICZ ◽  
Pawel FIGIEL ◽  
Marta SABARA
Keyword(s):  
Temperature Increase ◽  
Heating Rates ◽  
Linear Change ◽  
Dry Air ◽  
Isothermal Conditions ◽  
Gaseous Products ◽  
Heterogeneous Processes ◽  
Temperature Ranges ◽  
Higher Temperature ◽  
Kinetics Of

The results of investigations on pyrolysis and oxidation of pure polyacrylonitrile (PAN) and its mixture with N,N-dimethylformamide (DMF) under non-isothermal conditions at linear change of samples temperature in time are presented. In each case process proceeded in different way. During pyrolysis of pure PAN the material containing mainly the product after PAN cyclization was obtained, while pyrolysis of PAN+DMF mixture gave the product after cyclization and stabilization. Under conditions of measurements, in both temperature ranges, series of gaseous products were formed.For the PAN-DMF system measurements at different samples heating rates were performed. The obtained results were in accordance with the kinetics of heterogeneous processes theory. The process rates in stages increased along with the temperature increase, and TG, DTG and HF function curves were shifted into higher temperature range. This means that the process of pyrolysis and oxidation of PAN in dry air can be carried out in a controlled way.http://dx.doi.org/10.5755/j01.ms.17.1.246

Influence of Heating Rates On the Toxicity of Evolved Combustion Products: Results and a System for Research

1983 ◽  
Vol 1 (6) ◽  
pp. 465-479 ◽  
Author(s):  
Shayne Cox Gad ◽  
Ann C. Smith
Keyword(s):  
Decomposition Rate ◽  
High Density Polyethylene ◽  
Combustion Products ◽  
Douglas Fir ◽  
High Density ◽  
Heating Rates ◽  
Decomposition Products ◽  
Sample Heating ◽  
Rate Of Heating

The significance of the rate of heating of materials to the nature and toxi cologic consequences of combustion products formed by natural and man-made products was evaluated using a system designed to allow exact control and reproducibility of this variable. Using this system, the decomposition products of Douglas Fir, Hem Fir, and a high density polyethylene were characterized in terms of gases evolved, lethality, and ability to incapacitate at sample heating rates of 20, 30, 40, and 50 °C per minute. For all three materials, the rate of heating was found to have marked influences on both the decomposition prod ucts and their toxicologic impact. This influence was not such as to be ex plainable as just a decomposition rate phenomenon.

Output-Only Analysis for Modal Parameters Estimation of an Elastically Scaled Ship

2008 ◽  
Vol 52 (01) ◽  
pp. 45-56
Author(s):  
Giuliano Coppotelli ◽  
Daniele Dessi ◽  
Riccardo Mariani ◽  
Marcello Rimondi
Keyword(s):  
Life Prediction ◽  
Structural Response ◽  
Random Excitation ◽  
Parameters Estimation ◽  
Elastic Response ◽  
Modal Parameters ◽  
Practical Application ◽  
Scaled Model ◽  
Output Only ◽  
Ship Speed

The study of the ship structural response assumes an increasing importance as soon as the structures, characterized by much more lightness, are designed and built for faster vessels. This requisite implies a greater flexibility of the structures themselves, the elastic response of which has to be evaluated with accuracy in order to predict the dynamic behavior. In the present paper, a methodology for the identification of the modal parameters from the measurement of only the responses of a vibrating structure has been developed and applied to an elastically scaled model. This output-only technique is successfully applied to the segmented model of a real ship towed in the INSEAN linear basin. The broadband random excitation, provided by the loads exerted by an irregular sea pattern, induces a stochastic response of the model, which is monitored with accelerometers. The obtained results not only outline the parametric dependence of the modal properties on the ship speed, but also suggest a possible practical application of this technique for on-board structural monitoring and fatigue-life prediction.

FOAM TEMPERATURES DURING VAT PASTEURIZATION OF MILK PRODUCTS

1971 ◽  
Vol 34 (3) ◽  
pp. 133-139
Author(s):  
R. W. Dickerson ◽  
R. B. Read
Keyword(s):  
Milk Fat ◽  
Liquid Surface ◽  
Liquid Product ◽  
Ice Cream ◽  
Microbial Pathogens ◽  
Slow Heating ◽  
Milk Product ◽  
Heating Rates ◽  
Holding Period ◽  
Foam Thickness

Heating rates of foam during vat pasteurization were investigated to determine whether shorter holding times and higher processing temperatures would be feasible from a public health standpoint. A rake of 19 thermocouples, spaced 0.5 inch apart, was installed vertically in a 300-gal vat pasteurizer and the rake was adjusted to measure the temperature of the heated airspace, foam, and liquid product. With 200 gal of ice cream mix (16% milk fat), an 11-inch foam was generated on the liquid surface. The minimum temperature in the ice cream mix foam was below pasteurization temperature for 27 min of the 30-min holding period despite satisfactory temperatures as indicated by the product and airspace thermometers. When a 7-inch foam was generated above 218 gal of chocolate milk, the minimum foam temperature was below pasteurization temperature for the first 14 min of the holding period. Attempts to generate foams on milk were unsuccessful. Because of the slow heating rates of milk-product foams, holding times shorter than 30 min cannot ensure the inactivation of microbial pathogens in the foam, and, consequently, they are not recommended. Some foams should be held longer than 30 min to ensure pasteurization, and additional holding time needed may be computed from known values of foam thickness, airspace temperature , and heating rate of the liquid.

Study on the residual performance of RC beams exposed to processed temperatures and fire

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Sachin Vijaya Kumar ◽  
N. Suresh
Keyword(s):  
Failure Modes ◽  
Elevated Temperatures ◽  
Slow Heating ◽  
Maximum Temperature ◽  
Rc Beams ◽  
Heating Rates ◽  
Fast Heating ◽  
Content Type ◽  
Temperature Increment ◽  
Residual Performance

PurposeThe Reinforced Concrete(RC) elements are known to perform well during exposure to elevated temperatures. Hence, RC elements are widely used to resist the extreme heat developing from accidental fires and other industrial processes. In both of the scenarios, the RC element is exposed to elevated temperatures. However, the primary differences between the fire and processed temperatures are the rate of temperature increase, mode of exposure and exposure durations. In order to determine the effect of two heating modalities, RC beams were exposed to processed temperatures with slow heating rates and fire with fast heating rates.Design/methodology/approachIn the present study, RC beam specimens were exposed to 200 °C, to 800 °C temperature at 200 °C intervals for 2 h' duration by adopting two heating modes; Fire and processed temperatures. An electrical furnace with low-temperature increment and a fire furnace with standard time-temperature increment is adapted to expose the RC elements to elevated temperatures.FindingsIt is observed from test results that, the reduction in load-carrying capacity, first crack load, and thermal crack widths of RC beams exposed to 200 °C, and 600 °C temperature at fire is significantly high from the RC beams exposed to the processed temperature having the same maximum temperature. As the exposure temperature increases to 800 °C, the performance of RC beams at all heating modes becomes approximately equal.Originality/valueIn this work, residual performance, and failure modes of RC beams exposed to elevated temperatures were achieved through two different heating modes are presented.

The Effect of Temperature, Thickness, and Working Time on Adhesive Properties

2018 ◽  
Author(s):  
Nicholas Aerne ◽  
John P. Parmigiani
Keyword(s):  
Cantilever Beam ◽  
Design Process ◽  
Working Time ◽  
Effect Of Temperature ◽  
Control Group ◽  
Mode I ◽  
Mode Ii ◽  
Adhesive Properties ◽  
Loading Modes ◽  
Mode Ii Loading

The need for lightweight components and non-destructive fastening techniques has led to the growth of adhesive use in many industries. Modeling the behavior of adhesives in fastening joints can help in the design process to make an optimized joint. To optimize joints in the design process, the loading conditions, environmental conditions of service, thickness of bond, and bonding procedures all need to be refined for the adhesive of interest. However, in available technical data sheets of adhesives provided by manufactures there is a gap in what is sufficient to accurately model and predict the behavior of real-world adhesive conditions. This body of research presents the results of the effects of temperature, thickness, and working time on adhesive properties. These effects can be observed with test specimens from the loading modes of interest. The loading modes of interest are mode I and mode II loading for the current study. The specimen for mode I loading is the Double Cantilever Beam, and for mode II loading is the Shear Loaded Dual Cantilever Beam. The effect of temperature will be tested by testing each specimen at −20°C, 20°C, and 40°C. Two bond thicknesses for adhesive thickness effects were tested. The working time had a control group bonded in the recommended working time and an expired working time group where the specimens were not joined until 10 minutes had passed from the recommended working time. Triplicates of each specimen at the respective conditions were tested. The adhesive selected for this research was Plexus MA832. The results of the experiment show that adhesive factors such as temperature, thickness, and working time can have degrading effects on adhesive performance in mode I and mode II.

Isoconversional Kinetic Analysis of Pyrolysis of Malt Waste

2017 ◽  
Vol 899 ◽  
pp. 107-112
Author(s):  
Beatriz Cristina Silvério ◽  
Pedro Ivo Brandão e Melo Franco ◽  
Carolina Moreno de Freitas ◽  
Kássia Graciele dos Santos ◽  
Nelson Roberto Antoniosi Filho
Keyword(s):  
Low Cost ◽  
Estimation Methods ◽  
Slow Heating ◽  
Brewing Industry ◽  
Heating Rates ◽  
Spent Grain ◽  
Exponential Factors ◽  
Isoconversional Kinetic Analysis ◽  
Malt Waste ◽  
Energy Activation

Locally available malt waste or brewers' spent grain, a by-product of brewing industry, was found to be a low cost and promising biomass for pyrolysis. A kinetic studied of pyrolysis of malt waste was investigated by non-isothermal thermogravimetric analyses (TG-DTG), applying slow heating rates, 10, 15, 30 and 50 K/min, and well-defined conditions. Activation energies and Arrhenius exponential factors were inferred by different estimation methods: Kissinger, Ozawa, Starink, K-A-S and. The methods presented energy activation values of 214 - 238.23 kJ/mol. The Literature studies found activations energies values similar to those found for sugarcane bagasse pyrolysis and other types of biomasses with predominance of hemicelluloses, cellulose and lignin, respectively.

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