Ratchet Limits for a Crack in a Welded Pipe Subjected to a Cyclic Temperature Load and a Constant Mechanical Load

2011 ◽  
Author(s):  
Tianbai Li ◽  
Haofeng Chen ◽  
Weihang Chen ◽  
James Ure
Keyword(s):  
Yield Stress ◽  
Mechanical Load ◽  
Maximum Temperature ◽  
Limit Loads ◽  
Axial Tension ◽  
Temperature Load ◽  
Cyclic Temperature ◽  
Temperature Ranges ◽  
Welded Pipe ◽  
Symmetric Crack

This paper presents the ratchet limit analysis of a pipe with a symmetric crack in a mismatched weld by using the extended Linear Matching Method (LMM). Two loading conditions are considered: i) a cyclic temperature load and a constant internal pressure; and ii) a cyclic temperature load and a constant axial tension. Individual effects of i) the geometry of the Weld Metal (WM), ii) the size of the crack, iii) the location of the crack and iv) the yield stress of WM on the ratchet limits, maximum temperature ranges to avoid ratchetting and limit loads are investigated. Influence functions of the yield stress of WM on the maximum temperature ranges and limit loads are generated. The results confirm the applicability of the extended LMM to the cracked welded pipe.

scholarly journals On the Ratchet Analysis of a Cracked Welded Pipe

2011 ◽  
Vol 134 (1) ◽  
Author(s):  
Tianbai Li ◽  
Haofeng Chen ◽  
Weihang Chen ◽  
James Ure
Keyword(s):  
Yield Stress ◽  
Maximum Temperature ◽  
Limit Loads ◽  
Axial Tension ◽  
Circumferential Crack ◽  
Temperature Load ◽  
Cyclic Temperature ◽  
Temperature Ranges ◽  
Welded Pipe ◽  
Linear Matching Method

This paper presents the ratchet limit analysis of a pipe with an axisymmetric circumferential crack in a mismatched weld by using the extended linear matching method (LMM). Two loading conditions are considered: (i) a cyclic temperature load and a constant internal pressure and (ii) a cyclic temperature load and a constant axial tension. Individual effects of (i) the geometry of the Weld Metal (WM), (ii) the size of the crack, (iii) the location of the crack, and (iv) the yield stress of WM on the ratchet limits, maximum temperature ranges to avoid ratchetting, and limit loads are investigated. Influence functions of the yield stress of WM on the maximum temperature ranges and limit loads are generated. The results confirm the applicability of the extended LMM to the cracked welded pipe.

scholarly journals Quantifying sea surface temperature ranges of the Arabian Sea for the past 20 000 years

2011 ◽  
Vol 7 (4) ◽  
pp. 1337-1349 ◽  
Author(s):  
G. M. Ganssen ◽  
F. J. C. Peeters ◽  
B. Metcalfe ◽  
P. Anand ◽  
S. J. A. Jung ◽  
...  
Keyword(s):  
Arabian Sea ◽  
Isotope Composition ◽  
Planktonic Foraminifera ◽  
Sediment Cores ◽  
Maximum Temperature ◽  
Physical Parameters ◽  
Seasonal Temperature ◽  
Mean Values ◽  
The Past ◽  
Temperature Ranges

Abstract. The oxygen isotopic composition of planktonic foraminifera tests is one of the widest used geochemical tools to reconstruct past changes of physical parameters of the upper ocean. It is common practice to analyze multiple individuals from a mono-specific population and assume that the outcome reflects a mean value of the environmental conditions during calcification of the analyzed individuals. Here we present the oxygen isotope composition of individual specimens of the surface-dwelling species Globigerinoides ruber and Globigerina bulloides from sediment cores in the Western Arabian Sea off Somalia, inferred as indicators of past seasonal ranges in temperature. Combining the δ18O measurements of individual specimens to obtain temperature ranges with Mg/Ca based mean calcification temperatures allows us to reconstruct temperature extrema. Our results indicate that over the past 20 kyr the seasonal temperature range has fluctuated from its present value of 16 °C to mean values of 13 °C and 11 °C for the Holocene and LGM, respectively. The data for the LGM suggest that the maximum temperature was lower, whilst minimum temperature remained approximately constant. The rather minor variability in lowest summer temperatures during the LGM suggests roughly constant summer monsoon intensity, while upwelling-induced productivity was lowered.

Computational analysis of temperature distribution in microwave-heated potatoes

2020 ◽  
Vol 26 (6) ◽  
pp. 465-474
Author(s):  
Deepak Singh ◽  
Dhananjay Singh ◽  
Sattar Husain
Keyword(s):  
Mathematical Model ◽  
Temperature Distribution ◽  
Computational Analysis ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Maximum Temperature ◽  
Bacterial Inactivation ◽  
Food Material ◽  
Drying Time ◽  
Temperature Ranges

This research article reports the computational analysis of temperature distribution in microwave-heated convenience food such as potato. The detailed study of temperature (because temperature is a function of bacterial inactivation) and microwave powers along with drying time for the preservation of food material has been presented. Therefore, a mathematical model for potato sample is developed to predict the behavior of temperature distribution at each possible point and different shapes (slab, cylindrical, and spherical) of food material. The developed mathematical model is programmed by MATLAB software. Another parameter, microwave power is also a function of temperature. The ranging values of various microwave powers (125 W, 375 W, 625 W, 875 W, and 1250 W) along with different values of drying time (0 to 10 minutes) have been used for computation. The obtained results show the uniformity of temperature distribution throughout the whole product in the form of a three-dimensional structure. The model provides the minimum and maximum temperature ranges in specimens without performing an experiment which depicts the condition of bacterial inactivation.

scholarly journals Mechanical Properties of the Ternary L12 Compound Co3(Al,W) in Single and Polycrystalline Forms

2011 ◽  
Vol 278 ◽  
pp. 1-6 ◽  
Author(s):  
Haruyuki Inui ◽  
Takashi Oohashi ◽  
Norihiko L. Okamoto ◽  
Kyosuke Kishida ◽  
Katsushi Tanaka
Keyword(s):  
Mechanical Properties ◽  
Yield Stress ◽  
Elastic Constants ◽  
Solid Solution Hardening ◽  
Anomalous Increase ◽  
Thermally Activated ◽  
Cauchy Pressure ◽  
Slip Planes ◽  
Temperature Ranges ◽  
L12 Structure

The mechanical properties of Co3(Al,W) with the L12 structure have been investigated both in single and polycrystalline forms. The values of all the three independent single-crystal elastic constants and polycrystalline elastic constants of Co3(Al,W) experimentally determined by resonance ultrasound spectroscopy at liquid helium temperature are 15~25% larger than those of Ni3(Al,Ta) but are considerably smaller than those previously calculated. When judged from the values of Poisson’s ratio, Cauchy pressure and ratio of shear modulus to bulk modulus (Gh/Bh), the ductility of Co3(Al,W) is expected to be sufficiently high. In the yield stress-temperature curve, a rapid decrease and an anomalous increase in yield stress is observed in the low and intermediate (1000-1100 K) temperature ranges, respectively. The former is concluded to be due to the solid-solution hardening effect while the latter is attributed to thermally activated cross-slip of APB-coupled a/2<110> superpartial dislocations from octahedral to cube slip planes.

Temperature Spectrums of an Automotive Environment for Fatigue Reliability Analysis

1994 ◽  
Vol 37 (6) ◽  
pp. 19-25
Author(s):  
Jimmy Hu ◽  
Ken Salisbury
Keyword(s):  
Heat Dissipation ◽  
Sun Exposure ◽  
Maximum Temperature ◽  
Fatigue Reliability ◽  
Temperature Spectrum ◽  
Electronic Products ◽  
Automotive Components ◽  
Thermal Fatigue Life ◽  
Temperature Ranges ◽  
Nominal Temperature

The temperature spectrum of an automotive environment is a necessary input to predict thermal fatigue life, to estimate product reliability, and to specify accelerated thermal cycle testing for automotive components. This paper investigates the temperature profiles of electronic products located in the engine compartment (EC), the engine-mounted (EM) area, and the passenger/luggage (P/L) compartment, and develops the nominal temperature spectrums for these vehicle locations. The daily climatic temperatures of various geographical areas in the U.S. are analyzed. The effects of sun exposure and operational heat dissipation on the maximum temperature in three vehicle compartments are investigated. Due to the proportionality of mechanical stress/strain ranges and temperature ranges, the temperature spectrums are constructed by using the rainflow method for fatigue cycle counting.

Plastic Limit Loads for Slanted Through-Wall Cracks in Cylinder and Plate Based on Finite Element Limit Analyses

2014 ◽  
Vol 136 (3) ◽  
Author(s):  
Doo-Ho Cho ◽  
Young-Hwan Choi ◽  
Nam-Su Huh ◽  
Do-Jun Shim ◽  
Jae-Boong Choi
Keyword(s):  
Finite Element ◽  
Crack Opening ◽  
Limit Load ◽  
Correction Factors ◽  
Plastic Limit ◽  
Opening Displacement ◽  
Limit Loads ◽  
Axial Tension ◽  
Reference Stress ◽  
Plastic Limit Load

The plastic limit load solutions for cylinder and plate with slanted through-wall cracks (TWCs) are developed based on the systematic three-dimensional (3D) finite element (FE) limit analyses. As for loading conditions, axial tension, global bending, and internal pressure are considered for a cylinder with slanted circumferential TWC, whereas, axial tension and internal pressure are considered for a plate and a cylinder with slanted axial TWC. Then, the verification of FE model and analysis procedure employed in the present numerical work was confirmed by employing the existing solutions for both cylinder and plate with idealized TWC. Also, the geometric variables of slanted TWC which can affect plastic limit loads were considered. Based on the systematic FE limit analysis results, the slant correction factors which represent the effect of slanted TWC on plastic limit load were provided as tabulated solutions. By adopting these slant correction factors, the plastic limit loads of slanted TWC can be directly estimated from existing solutions for idealized TWC. Furthermore, the modified engineering estimations of plastic limit loads for slanted TWC are proposed based on equilibrium equation and von Mises yield criterion. The present results can be applied either to diverse structural integrity assessments or for accurate estimation of fracture mechanics parameters such as J-integral, plastic crack opening displacement (COD) and C*-integral for slanted TWC based on the reference stress concept (Kim, et al., 2002, “Plastic Limit Pressure for Cracked Pipes Using Finite Element Limit Analyse,” Int. J. Pressure Vessels Piping, 79, pp. 321–330; Kim, et al., 2001, “Enhanced Reference Stress-Based J and Crack Opening Displacement Estimation Method for Leak-Before-Break Analysis and Comparison With GE/EPRI Method,” Fatigue Fract. Eng. Mater. Struct., 24, pp. 243–254; Kim, et al., 2002, “Non-Linear Fracture Mechanics Analyses of Part Circumferential Surface Cracked Pipes,” Int. J. Fract., 116, pp. 347–375.)

scholarly journals Assessment of indoor thermal environment of Aceh house based on WBGT index

2021 ◽  
Vol 881 (1) ◽  
pp. 012023
Author(s):  
Muslimsyah ◽  
A Munir ◽  
Y Away ◽  
Abdullah ◽  
K Huda ◽  
...  
Keyword(s):  
Thermal Comfort ◽  
Natural Ventilation ◽  
Thermal Environment ◽  
Ventilation System ◽  
Vernacular Architecture ◽  
Maximum Temperature ◽  
Cooling Process ◽  
Temperature Index ◽  
Indoor Thermal Environment ◽  
Temperature Ranges

Abstract Thermal comfort is one of the standard assessments of building thermal environment. Air movement is an important parameter for in a naturally ventilated to achieve thermal comfort by accelerating the evaporative cooling process on the human body. Aceh House has a standard of thermal comfort with a vernacular architecture with a natural ventilation system. This vernacular architectural building has a fairly high harmonization of the environment because it has undergone a process of adaptation. In this study, observations were made at the Original House (OH), the Adaptive Reuse House (ARH), and the Aceh Modified House (AMH). By using the method of assessing changes in environmental comfort, using Wet Bulb Temperature Index (WBGT) method, the minimum and maximum temperature ranges are 25°C and 30°C. In the WBGT thermal rating, AMH has the higher thermal and is followed by ARH and OH respectively. Thus, OH has lower thermal compared to other Aceh houses.

Shakedown Behavior of a Two-Layer Beam Considering Ductile Damage Under Thermo-Mechanical Loadings

2010 ◽  
Author(s):  
Xiao-Tao Zheng ◽  
Fu-Zhen Xuan
Keyword(s):  
Yield Stress ◽  
Kinematic Hardening ◽  
Engineering Application ◽  
Bending Moment ◽  
Ductile Damage ◽  
Hardening Material ◽  
Limit Loads ◽  
Stress Limit ◽  
Shakedown Limit ◽  
Temperature Loads

In this paper, the nonlinear kinematic hardening material based on Armstrong-Fredrick model coupled with ductile damage was used to estimate the shakedown behavior of a two-layer beam under constant bending moment and cyclic temperature loads. The shakedown limit loads were determined by the accumulation of plastic straining after enough cycles under various loads combination and presented by the Bree-type diagram. The results indicated that the twice yield stress limit of shakedown behavior was considerable conservative compared to the shakedown domain obtained by nonlinear kinematic hardening model without damage. However, shakedown limit loads considering ductile damage decreased remarkably compared with the undamaged material modal, In this case, the twice yield stress limit of shakedown behavior may be not safe for engineering application, especially when the thermal load is prominent.

Clamp Load Decay in Preloaded Dissimilar Lightweight-Material Joints due to Cyclic Temperature

2014 ◽  
Author(s):  
Sayed A. Nassar ◽  
Amir Kazemi ◽  
Mohamad Dyab
Keyword(s):  
Finite Element ◽  
Temperature Profile ◽  
Thermal Loading ◽  
Dissimilar Materials ◽  
Temperature Dependent ◽  
Element Analysis ◽  
Temperature Load ◽  
Cyclic Temperature ◽  
Material Creep ◽  
Aluminum And Magnesium Alloys

Experimental and Finite Element methods are used for investigating the effect of cyclic thermal loading on the clamp load decay in preloaded single-lap bolted joints that are made of dissimilar-materials. Joint material combinations include steel and lightweight materials such as aluminum and magnesium alloys, with various different thicknesses. The range of cyclic temperature profile varies between −20°C and +150°C. A computer-controlled environmental chamber is used for generating the desired cyclic temperature profile and duration. Real time clamp load data is collected using high-temperature load cells. Percent clamp load decay is investigated for various combinations of joint materials, initial preload level, and test specimen thicknesses. Thermal and material creep finite element analysis is performed using temperature-dependent mechanical properties. FEA result has provided insight into interesting experimental observations regarding model predictions and the experimental data is discussed.

scholarly journals Analysis of hydrometeorological variables over the transboundary Komadugu-Yobe basin, West Africa

2019 ◽  
Vol 11 (4) ◽  
pp. 1339-1354 ◽  
Author(s):  
O. E. Adeyeri ◽  
P. Laux ◽  
A. E. Lawin ◽  
S. O. Ige ◽  
H. Kunstmann
Keyword(s):  
Time Scales ◽  
Minimum Temperature ◽  
River Discharge ◽  
Kendall Test ◽  
Mitigation Measures ◽  
Maximum Temperature ◽  
Spatiotemporal Trends ◽  
Increasing Trend ◽  
Temperature Ranges ◽  
Positive Correlations

Abstract Spatiotemporal trends in daily observed precipitation, river discharge, maximum and minimum temperature data were investigated between 1971 and 2013 in the Komadugu-Yobe basin. Significant change points in time series are corrected using Adapted Caussinus-Mestre Algorithm for homogenizing Networks of Temperature series algorithm. Mann–Kendall test and Sen's slope are used to estimate the trend and its magnitude at dry, wet and annual season time scales, respectively. Preliminary results show an increasing trend of the observed variables. There is a latitudinal increase (decrease) in the basin temperature (precipitation) from lower to higher latitudes. The minimum temperature (0.05 °C/year) increases faster than the maximum temperature (0.03 °C/year). Overall, the percentage changes in minimum temperature range between 3 and 10% while that of maximum temperature ranges between 1 and 3%. Due to precipitation dependence on regional characteristics, the highest percentage change was recorded in precipitation with values between −5 and 97%. In all time scales, river discharge and precipitation have strong positive correlations while the correlation between river discharge and temperature is negative. It is imperative to advocate and support positive developmental practices as well as establishing necessary mitigation measures to cope with the effects of climate in the basin.

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