Probabilistic Design and Analysis of Pressure Measuring Probes for Creep Behavior

2017 ◽  
Author(s):  
Dattatraya Parle
Keyword(s):  
Creep Behavior ◽  
Probabilistic Approach ◽  
Operating Conditions ◽  
Model Complexity ◽  
Creep Model ◽  
Operating Parameters ◽  
Secondary Creep ◽  
Operating Pressure ◽  
Probabilistic Design ◽  
Input Parameters

Pressure probes are typically used to measure the pressure of a fluid stream. These probes are designed to serve for 25 years life under operating pressure and temperature conditions. Therefore, such pressure probes are also designed for safe creep behavior. Typically creep is time dependent phenomenon and it can be classified as Primary, Secondary and Tertiary creep. In the literature, the creep phenomenon is studied analytically and numerically. Literature review reveals that creep analysis requires special material models and its selection depends on operating conditions. This work presents FEA based probabilistic design and analysis of pressure measuring probes using ANSYS which has several creep models depending on type of creep phenomenon. Probes in this study are subjected to primary and secondary creep. Therefore, this work proposes combined time hardening creep model. Combined time hardening model has 7 coefficients. This further increases the complexity of the model. Apart from the model complexity, there are various other design and operating parameters which further complicates the creep behavior. Some of the important design and operating parameters are length, diameter and tip dimensions along with pressure and temperature. Thus there are around 16 parameters which controls the creep behavior of pressure measuring probe. Traditional design process of probe is based on deterministic analysis which involves the use of safety factors as a way of accounting for uncertainty in design input parameters. This can often results in overly conservative designs. Moreover, to understand optimal creep behavior of probes under several uncertainties in input parameters becomes a challenging. Therefore, this work presents probabilistic approach as opposed to a deterministic approach to understand the combined effect of several uncertain parameters on creep behavior of probes. This work not only determines probability of probe failure more accurately but also determines the sensitivity of each parameter during creep phenomenon using FEA.

Effect of the operating parameters on the separation of metal chelates using low pressure reverse osmosis membrane (LPROM)

2000 ◽  
Vol 41 (10-11) ◽  
pp. 135-142 ◽  
Author(s):  
Z. Ujang ◽  
G.K. Anderson
Keyword(s):  
Factorial Design ◽  
Metal Removal ◽  
Feed Solution ◽  
Metal Chelates ◽  
Operating Conditions ◽  
Operating Parameters ◽  
Operating Pressure ◽  
Permeate Flux ◽  
Experimental Conditions ◽  
Central Composite

This paper describes an investigation on the effect of operating parameters on the separation of metal chelates using LPROM. The objective of this study was to optimise the process of metal chelates removal by a LPROM using statistical factorial design. Factorial experiment by statistical design was applied, in which a central composite factorial design (half replicate) was used, then followed up by a star design to give a central composite factorial design. A bench-scale spiral wound configuration of sulphonated polysulphone LPROM was used at various operating conditions, i.e. operating conditions, solute concentrations, EDTA, pH and temperature. It has been shown experimentally that the effect of pressure is non-linear with respect to percentage of metal removal at different concentrations of metal ions in the feed solution. Observation of the response surface implies that the operating pressure was not the significant parameter in determining the percentage of zinc removal in the LPROM. The operating pressure, temperature and concentration of EDTA in the feed solution were the most significant parameters for permeate flux variation. It can also be concluded that for a given set of feed and experimental conditions, permeate flux increased linearly with operating pressure and temperature. The other parameters, i.e. the concentration of zinc in the feed solution and pH, were not statistically significant.

Creep-Relaxation Modeling of HDPE and Polyvinyl Chloride Bolted Flange Joints

2020 ◽  
Vol 142 (5) ◽  
Author(s):  
Rahul Palaniappan Kanthabhabha Jeya ◽  
Zijian Zhao ◽  
Abdel-Hakim Bouzid
Keyword(s):  
Polyvinyl Chloride ◽  
Creep Behavior ◽  
Creep Property ◽  
Dissimilar Materials ◽  
Operating Conditions ◽  
Relaxation Behavior ◽  
Polymer Materials ◽  
Creep Model ◽  
Tension And Compression ◽  
Bolted Flange

Abstract Similar to many polymer materials, high-density polyethylene (HDPE) and polyvinyl chloride (PVC) show a clear creep behavior, the rate of which is influenced by temperature, load, and time. Most bolted flange joints undergo relaxation under compression, which is caused by the creep of the material. However, the creep property of the two polymers is different under tension and compression loading. Since the sealing capacity of a flanged gasketed joint is impacted by the amount of relaxation that takes place, it is important to properly address and predict the relaxation behavior due to flange creep under compression and thereby reducing the chances of leakage failure of HDPE and PVC bolted flange joints. The main objective of this study is to analyze the compressive creep behavior of HDPE and PVC flanges under normal operating conditions. This is achieved by developing a respective creep model for the two materials, based on their short-term experimental creep test data. Both numerical and experimental simulations of the polymeric flange relaxation behavior are conducted on an NPS 3 class 150 bolted flange joint of dissimilar materials, where one of the flanges is made of HDPE or PVC material and the other one is made of steel SA105. The study also provides a clear picture on how the compression creep data of ring specimen may be utilized for predicating the flange bolt load relaxation over time at the operating temperatures.

Gas Turbine Blade Stress and Temperature Sensitivity to Turbine Inlet Profile and Cooling Flow

2012 ◽  
Author(s):  
Beom Soo Kim ◽  
Bum Shin Kim ◽  
Woosung Choi ◽  
Grant O. Musgrove ◽  
John McFarland ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Gas Flow ◽  
Probabilistic Approach ◽  
Geographic Location ◽  
Operating Conditions ◽  
Operating Parameters ◽  
Internal Cooling ◽  
Cooling Flow ◽  
Turbine Inlet ◽  
Range Of Values

Actual operating conditions in the hot section of a gas turbine vary from the design condition due to factors such as geographic location, component wear, and fuel composition. Turbine design practices typically use a conservative approach that requires checking the sensitivity of operating parameters such as turbine inlet profiles, cooling flows, and heat transfer correlations on component temperatures and stresses. In most cases, a sensitivity check is limited to analyzing the bounds of a range of values for only a few input parameters, whereby the inputs that produce the most conservative results are carried through the remainder of the analysis. For flow path components, however, multiple inputs must be evaluated over a range of values due to the interaction of the hot gas flow field and internal cooling systems. The study presented in this paper uses a probabilistic approach to develop surrogate models to evaluate the sensitivity of a set of operating parameters on the predicted blade temperatures and stresses. Commercially available software is utilized to predict blade temperatures and stresses for the first two stages of an industrial gas turbine. The operating parameters define the blade cooling flow and the shape and values of the turbine inlet profiles of total temperature and total pressure. The results of the study show the spatially resolved sensitivity of the operating parameters on blade temperature and stress distributions.

Creep Modeling of Polyvinyl Chloride Bolted Flange Joints

2017 ◽  
Author(s):  
Zijian Zhao ◽  
Rahul Palaniappan Kanthabhabha Jeya ◽  
Abdel-Hakim Bouzid
Keyword(s):  
Polyvinyl Chloride ◽  
Creep Behavior ◽  
Compressive Load ◽  
Dissimilar Materials ◽  
Operating Conditions ◽  
Relaxation Behavior ◽  
Creep Model ◽  
Compression Creep ◽  
Material Creep ◽  
Bolted Flange

Alike other polymer material, PolyVinyl Chloride (PVC) shows a clear creep behavior, the rate of which is influenced by temperature, load and time. Polyvinyl chloride bolted flange joints undergo relaxation under compression for which the material creep properties are different than those under tension. Since the sealing capacity of a flanged gasketed joint is impacted by the amount of relaxation that takes place, it is important to properly address and predict the relaxation behavior due to flange creep under compression and reduce the chances of leakage failure of PVC flange joints. The main objective is study the creep behavior of PVC flanges under the influence of normal operating conditions. This is achieved by developing a PVC creep model based on creep test data under various compressive load, temperature and time. A simulation of a PVC flange relaxation behavior bot numerically and experimentally is conducted on an NPS 3 class 150 bolted flange joint of dissimilar materials one made of PVC material and the other one by steel SA105. The study also provides a clear picture on how the compression creep data on Ring specimen may be utilized for predicating the flange performance under various operating temperatures with time.

Investigations on Creep Behavior of P91-Type Steel Using Combined Creep Damage Model

2013 ◽  
Author(s):  
Fujun Liu ◽  
Ping Tang ◽  
Shuai Kong ◽  
Zhangwei Ling ◽  
Muling Zheng ◽  
...  
Keyword(s):  
Constitutive Model ◽  
Creep Behavior ◽  
Power Plants ◽  
Damage Model ◽  
Creep Damage ◽  
Damage Function ◽  
Creep Model ◽  
Secondary Creep ◽  
Type Steel ◽  
Damage Theory

P91-type steel is widely used for the high-temperature pipe work components in advanced power plants. The creep behavior of the P91-type steel has been studied by many researchers during the past years. Since it is well known that the creep behavior of P91-type steel cannot be satisfactorily described by a simple, Arrhenius-type, power-law constitutive model. While Norton-Bailey creep is a deviatoric temperature-dependent creep model, furbished with a time-hardening creep model, which is the most common model for modeling primary and secondary creep together, and Kachanov-Rabotnov creep damage theory described with Norton creep model can be used to model tertiary creep. Both of them based on Norton creep constitutive equation. In this paper, based on the Norton-Bailey creep law and Kachanov-Rabotnov creep damage theory, a new combined constitutive model has been developed, in which the creep and damage function are both considered as nonlinear variables. The damage parameters in the model have clear physical meaning and can be determined from the benchmark experiment. The results indicated that this combined damage model was applicable to describe the full damage evolution for P91-type steel.

scholarly journals Creep Strain Analysis and an Improved Creep Model of Granite Based on the Ratio of Deviatoric Stress-Peak Strength under Different Confining Pressures

2021 ◽  
Author(s):  
Li Qian ◽  
Jianhai Zhang ◽  
Xianliang Wang ◽  
Yonghong Li ◽  
Ru Zhang ◽  
...  
Keyword(s):  
Elastic Modulus ◽  
Creep Behavior ◽  
Viscosity Coefficient ◽  
Deviatoric Stress ◽  
Peak Strength ◽  
Creep Model ◽  
Secondary Creep ◽  
Creep Tests ◽  
Underground Powerhouse ◽  
Confining Pressures

Abstract Creep refers to the deformation of rock with time under long-term applied stress, which occur in most underground engineering. The creep behavior of granite in Shuang jiangkou underground powerhouse in Western Sichuan Province, China, was studied by creep tests. Based on test results, a new parameter DPR, the ratio of deviatoric stress to peak strength, is proposed. DPR is found to be a key parameter to describe creep parameters such as instantaneous elastic modulus, creep elastic modulus, and viscosity coefficient of rock under different confining pressures. Creep tests show that instantaneous elastic modulus increases with the increase of DPR. Creep elastic modulus increases when DPR changes from 0.54 to 0.7004, but decreases when DPR is from 0.7004 to 0.88, indicating fractures in rock closes firstly and then new fractures are generated. The viscosity coefficient of the rock increases first and then decreases with the increase of DPR, and when DPR = 0.7171, viscosity coefficient is maximum, indicating the time for rock to reach stability is the longest in creep tests. By introducing DPR and confining pressure into creep model, which interconnect creep parameters in a unified expression, an improved generalized Kelvin creep model is proposed which can accurately describe the primary and the secondary creep behavior of granite under given deviatoric stresses and confining pressures.

Creep behavior of fine-grained frozen soils

1991 ◽  
Vol 28 (4) ◽  
pp. 489-502 ◽  
Author(s):  
H. Wijeweera ◽  
R. C. Joshi
Keyword(s):  
Water Content ◽  
Creep Behavior ◽  
Creep Model ◽  
Secondary Creep ◽  
Total Water Content ◽  
Total Water ◽  
Creep Tests ◽  
Frozen Soils ◽  
Fine Grained ◽  
Creep Stress

Uniaxial compressive creep tests were conducted on saturated samples of six fine-grained frozen soils. The creep behavior of the soils with respect to variation in the creep stress, temperature, and total water content is examined. The test results indicate existence of a unique relationship between the secondary creep rate, [Formula: see text], and the time to the onset of the secondary creep stage, ts, which is dependent only on the soil type. The values [Formula: see text], ts, and the initial strain rate are found to be directly related to the relative creep load (creep stress to peak strength ratio) acting on the soil. Results indicate these relationships to be independent of temperature. A method of analysis is presented whereby the creep behavior of a fine-grained frozen soil at various stresses, temperatures, and total water contents can be predicted, using data from a few creep tests conducted at only one reference temperature and total water content. A secondary creep model is introduced that predicts the creep behavior reasonably well in fine-grained frozen soils. The results obtained from this study are of importance to practicing engineers. Key words: fine grained, frozen soils, creep, load, temperature, water content, compressive strength, creep model.

scholarly journals Curve Fitting for Damage Evolution through Regression Analysis for the Kachanov–Rabotnov Model to the Norton–Bailey Creep Law of SS-316 Material

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5518
Author(s):  
Mohsin Sattar ◽  
Abdul Rahim Othman ◽  
Maaz Akhtar ◽  
Shahrul Kamaruddin ◽  
Rashid Khan ◽  
...  
Keyword(s):  
Creep Behavior ◽  
Creep Deformation ◽  
Curve Fitting ◽  
Elevated Temperatures ◽  
Creep Behaviour ◽  
Creep Damage ◽  
Tertiary Creep ◽  
Creep Model ◽  
Secondary Creep ◽  
Dog Bone

In a number of circumstances, the Kachanov–Rabotnov isotropic creep damage constitutive model has been utilized to assess the creep deformation of high-temperature components. Secondary creep behavior is usually studied using analytical methods, whereas tertiary creep damage constants are determined by the combination of experiments and numerical optimization. To obtain the tertiary creep damage constants, these methods necessitate extensive computational effort and time to determine the tertiary creep damage constants. In this study, a curve-fitting technique was proposed for applying the Kachanov–Rabotnov model into the built-in Norton–Bailey model in Abaqus. It extrapolates the creep behaviour by fitting the Kachanov–Rabotnov model to the limited creep data obtained from the Omega-Norton–Bailey regression model and then simulates beyond the available data points. Through the Omega creep model, several creep strain rates for SS-316 were calculated using API-579/ASME FFS-1 standards. These are dependent on the type of the material, the flow stress, and the temperature. In the present work, FEA creep assessment was carried out on the SS-316 dog bone specimen, which was used as a material coupon to forecast time-dependent permanent plastic deformation as well as creep behavior at elevated temperatures and under uniform stress. The model was validated with the help of published experimental creep test data, and data optimization for sensitivity study was conducted by applying response surface methodology (RSM) and ANOVA techniques. The results showed that the specimen underwent secondary creep deformation for most of the analysis period. Hence, the method is useful in predicting the complete creep behavior of the material and in generating a creep curve.

Effect of operating conditions on rejection of anionic pollutants in the water environment by nanofiltration especially in very low pressure range

1996 ◽  
Vol 34 (9) ◽  
pp. 149-156 ◽  
Author(s):  
C. Ratanatamskul ◽  
K. Yamamoto ◽  
T. Urase ◽  
S. Ohgaki
Keyword(s):  
Water Environment ◽  
Chloride Ions ◽  
Operating Conditions ◽  
Transmembrane Pressure ◽  
Operating Pressure ◽  
Nanofiltration Membranes ◽  
Single Solution ◽  
Crossflow Velocity ◽  
Membrane Type ◽  
New Generation

The recent development of new generation LPRO or nanofiltration membranes have received attraction for application in the field of wastewater and water treatment through an increasingly stringent regulation for drinking purpose and water reclamation. In this research, the application on treatment of anionic pollutants (nitrate, nitrite, phosphate, sulfate and chloride ions) have been investigated as functions of transmembrane pressure, crossflow velocity and temperature under very much lower pressure operation range (0.49 to 0.03 MPa) than any other previous research used to do. Negative rejection was also observed under very much low range of operating pressure in the case of membrane type NTR-7250. Moreover, the extended Nernst-Planck model was used for analysis of the experimental data of the rejection of nitrate, nitrite and chloride ions in single solution by considering effective charged density of the membranes.

Relationships between Population Dynamics and Operating Parameters in an Activated Sludge-Plant by Statistical Analysis

1992 ◽  
Vol 25 (4-5) ◽  
pp. 399-400 ◽  
Author(s):  
L. Cingolani ◽  
M. Cossignani ◽  
R. Miliani
Keyword(s):  
Population Dynamics ◽  
Statistical Analysis ◽  
Activated Sludge ◽  
Treatment Plant ◽  
Operating Conditions ◽  
Statistical Analyses ◽  
Operating Parameters ◽  
Aerobic Treatment

Statistical analyses were applied to data from a series of 38 samples collected in an aerobic treatment plant from November 1989 to December 1990. Relationships between microfauna structure and plant operating conditions were found. Amount and quality of microfauna groups and species found in activated sludge proved useful to suggest the possible causes of disfunctions.

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