Allowable Stress Design of Rupture Strength Based on Confidence Level of 9Cr-1Mo Steel

2012 ◽  
Vol 155-156 ◽  
pp. 1107-1111
Author(s):  
Ji Bin Pei ◽  
Yun Feng Zhao ◽  
Shao Ping Yu ◽  
Jie Zhao
Keyword(s):  
Safety Factor ◽  
Rupture Strength ◽  
Creep Rupture ◽  
Parameter Method ◽  
Allowable Stress ◽  
Reliability Design ◽  
Factor Method ◽  
Z Parameter ◽  
Rupture Data ◽  
Allowable Stress Design

The scattering of creep rupture data was represented by Z-parameter method based on Larson-Miller method. It was verified that the values of Z were supported by normal distribution. After obtained the distribution characteristics of creep rupture data using Z-parameter, reliability design for rupture allowable stress was carried out according to design life. Safety factor method is used for safety guarantee in conventional rupture allowable stress design and minimum rupture strength method is used in some standard. In comparison with safety factor method and minimum rupture strength method, it can be seen that reliability design based on Z-parameter is more agree with experimental data than other methods. Reliability design provides more precise results by considering the real distribution of creep rupture property and provides more flexible choice for design due to the need of safety and economy.

Reliability Design for Allowable Stress of Creep Rupture Strength of 4Cr25Ni35 Steel

2012 ◽  
Vol 476-478 ◽  
pp. 2552-2555
Author(s):  
Ji Bin Pei ◽  
Yun Feng Zhao ◽  
Shao Ping Yu ◽  
Jie Zhao
Keyword(s):  
Experimental Data ◽  
Statistical Analysis ◽  
Rupture Strength ◽  
Creep Rupture ◽  
Parameter Method ◽  
Allowable Stress ◽  
Creep Rupture Strength ◽  
Reliability Design ◽  
Z Parameter ◽  
Rupture Data

Creep rupture data plays vital role in life prediction and safety assessment of high temperature components. In order to describe the scattering of the data, a statistical analysis of creep rupture data for 4Cr25Ni35 steel was performed by Z-parameter method. With the application of Z-parameter, reliability design for allowable stress of creep rupture strength was carried out according to design life. It is found that Manson-Haferd method appears better correlation results with experimental data. Statistical analysis shows that the scattering of Z-parameter for 4Cr25Ni35 steel is supported by normal distribution. Compared with safety factor method, the method based on Z-parameter can perform reliability design for allowable stress of creep rupture strength by considering the dispersibility of the rupture data. Reliability design based on Z-parameter is more agree with experimental data.

Reliability Design for Creep Rupture Strength of 2.25Cr-1Mo Steel

2011 ◽  
Vol 675-677 ◽  
pp. 507-510
Author(s):  
Ji Bin Pei ◽  
Yun Feng Zhao ◽  
Dong Ming Li ◽  
Jie Zhao ◽  
Lai Wang
Keyword(s):  
Rupture Strength ◽  
Creep Rupture ◽  
Parameter Method ◽  
Allowable Stress ◽  
Creep Rupture Strength ◽  
Reliability Design ◽  
Design Life ◽  
Real Distribution ◽  
Z Parameter ◽  
Rupture Data

A statistical analysis of creep rupture data for 2.25Cr-1Mo steel was performed. The scattering of creep rupture data was represented by Z-parameter method based on Manson-Haferd method. With the application of Z-parameter, reliability design for allowable stress of creep rupture strength was carried out according to design life. The higher the value of confidence level, the lower the allowable stress. In comparison with safety factor method and minimum rupture strength method, it can be seen that reliability design based on Z-parameter is more agree with experimental data than other methods. Reliability design provides more precise results by considering the real distribution of creep rupture property and provides more flexible choice for design due to the need of safety and economy.

Design of Rupture Strength Based on Confidence Level of HK40 Steel

2012 ◽  
Vol 499 ◽  
pp. 123-126
Author(s):  
Ji Bin Pei ◽  
Yun Feng Zhao ◽  
Shao Ping Yu ◽  
Jie Zhao
Keyword(s):  
Rupture Strength ◽  
Statistical Processing ◽  
Creep Rupture ◽  
Parameter Method ◽  
Allowable Stress ◽  
Creep Rupture Strength ◽  
Reliability Design ◽  
Strength Based ◽  
Z Parameter ◽  
High Temperature Components

The strength of high temperature components is designed according to creep rupture strength. A statistical processing of creep rupture data of HK40 steel was performed by Z-parameter method based on Larson-Miller method. The data has been studied to evaluate the distribution under different temperature and stress. And the distribution of Z-parameter was investigated. With the application of Z-parameter, reliability design for allowable stress of creep rupture strength was carried out according to design life. The results show that the distribution of Z-parameter is supported by normal distribution. In comparison with allowable stress designed by conventional safety factor method, reliability design based on Z-parameter is more agree with experimental data.

A New Approach of Reliability Design for Creep Rupture Property

2009 ◽  
Author(s):  
Jie Zhao ◽  
Dong-ming Li ◽  
Yuan-yuan Fang ◽  
Shi-jie Zhu
Keyword(s):  
Parametric Method ◽  
Stress Rupture ◽  
Creep Rupture ◽  
Parameter Method ◽  
Reliability Design ◽  
Safety Coefficient ◽  
Real Distribution ◽  
Z Parameter ◽  
Rupture Data ◽  
Temperature Time

It has been noted that the use of safety coefficient can deal with uncertainties existed in practical structures, while reliability concept provides more precise results by considering the real distribution of creep rupture property. Generally, creep rupture data of a heat-resistant steel can be compressed into a narrow band by using a temperature-time parametric method such as Larson-Miller or Manson-Haferd method. In order to describe the scattering of the data, the current paper proposes a “Z parameter” method to represent the magnitude of the deviation of the rupture data to master curve. Statistical analysis shows that the scattering of Z parameter for several types of steels is supported by normal distribution. Using this method, it is possible to achieve unified analysis of the creep rupture data in various temperature and stress conditions. Stress-TTP-Reliability curves (σ-TTP-R curves), Stress-Rupture time-Reliability curves (σ-tr-R curves) and Allowable stress-Temperature-Reliability curves ([σ]-T-R curves) are proposed which could embrace reliability concept into creep rupture property design.

A New Approach of Reliability Design For Creep Rupture Property

2010 ◽  
Vol 132 (6) ◽  
Author(s):  
Jie Zhao ◽  
Dong-ming Li ◽  
Yuan-yuan Fang ◽  
Shi-jie Zhu
Keyword(s):  
Parametric Method ◽  
Stress Rupture ◽  
Creep Rupture ◽  
Parameter Method ◽  
Heat Resistant Steel ◽  
Reliability Design ◽  
Z Parameter ◽  
Rupture Data ◽  
Temperature Parameter ◽  
Temperature Time

Generally, creep rupture data of a heat-resistant steel can be compressed into a narrow band by using a temperature-time parametric method such as the Larson–Miller or Manson–Haferd method. In order to describe the scattering of the data, the current paper proposes a “Z parameter” method to represent the magnitude of the deviation of the rupture data to master curve. Statistical analysis shows that the scattering of the Z parameter for several types of steels is supported by normal distribution. Using this method, it is possible to achieve unified analysis of the creep rupture data in various temperature and stress conditions. Stress-time temperature parameter-reliability curves (σ-TTP-R curves), stress-rupture time-reliability curves (σ-tr-R curves), and allowable stress-temperature-reliability curves ([σ]-T-R curves) are proposed, which could embrace the reliability concept into creep rupture property design.

Influence of Data Analysis Method and Allowable Stress Criterion on Allowable Stress of Gr.122 Heat Resistant Steel

2006 ◽  
Vol 129 (3) ◽  
pp. 449-453 ◽  
Author(s):  
Kouichi Maruyama ◽  
Kyosuke Yoshimi
Keyword(s):  
Data Analysis ◽  
Rupture Strength ◽  
Rupture Life ◽  
Creep Rupture ◽  
Allowable Stress ◽  
Short Term ◽  
Rupture Data ◽  
Asme Code ◽  
Term Creep

Long-term creep rupture life is usually evaluated from short-term data by a time-temperature parameter (TTP) method. The allowable stress of Gr.122 steel listed in the ASME code has been evaluated by this method and is recognized to be overestimated. The objective of the present study is to understand the causes of the overestimation and propose appropriate methodology for avoiding the overestimation. The apparent activation energy Q for rupture life of the steel changes from a high value of short-term creep to a low value of long-term creep. However, the decrease in Q is ignored in the conventional TTP analyses, resulting in the overestimation of rupture life. A multiregion analysis of creep rupture data is employed to avoid the overestimation; in the analysis creep rupture data are divided into a couple of regions so that the Q value is unique in each divided region. The multiregion analysis provides a good fit to the data and the lowest value of 105h creep rupture strength among the three ways of data analysis examined. A half of 0.2% proof stress cannot provide an appropriate boundary for dividing data to be used in the multiregion analysis. In the 2001 edition of the ASME code an F average concept has been proposed as a substitution for the safety factor of 2∕3 for average rupture stress. The allowable stress of Gr.122 steel changes significantly depending on the allowable stress criteria as well as the methods of rupture data analysis: i.e., from 74MPato48MPa.

scholarly journals ANALISIS KEKUATAN STRUKTUR HYDRAULIC LIFTING MACHINE DENGAN MENGGUNAKAN METODE ELEMEN HINGGA

SIMETRIS ◽  
2020 ◽  
Vol 14 (2) ◽  
pp. 39-45
Author(s):  
Ahmat Saebudin ◽  
Hendri Suryanto ◽  
Eva Hertnacahyani Herraprastanti
Keyword(s):  
Safety Factor ◽  
Allowable Stress ◽  
Von Mises ◽  
Allowable Stress Design

Hydraulic Lifting Machine merupakan jenis alat angkat yang didesain untuk memindahan barang ditempat yang relatif sempit. Dalam mendesain suatu alat selain fungsi dan kegunaannya kekuatan struktur merupakan salah satu aspek yang sangat penting untuk diperhatikan. Struktur tersebut haruslah mampu untuk menanggung beban yang timbul saat beroperasi dan memberikan keamanan bagi penggunanya dari kegagalan struktur. Oleh sebab itu tujuan dari penelitian ini adalah untuk menganalisis kekuatan struktur Hydraulic Lifting Machine dengan menggunakan metode elemen hingga. Berdasarkan hasil dari simulasi yang telah dilakukan dimana nilai tegangan resultan dan defleksi maksimum yang timbul pada struktur Hydraulic Lifting Machine yaitu pada beban kerja 100 kg tegangan resultannya sebesar 90,62 MPa dengan defleksi maksimum 4,39 mm, pada beban kerja 250 kg tegangan resultannya sebesar 218,51 MPa dengan defleksi 10,71 mm, pada beban kerja 500 kg tegangan resultannya sebesar 431,68 MPa dengan defleksi 21,25 mm, pada beban kerja 750 kg tegangan resultannya sebesar 644,84 MPa dengan defleksi 31,79 mm, dan pada beban kerja maksimal 1000 kg tegangan resultannya sebesar 858 MPa dengan defleksi 42,33 mm. Berdasarkan pada peraturan BS-5950 Structure Use of Steelwork in Building, nilai batas defleksi maksimumnya tidak boleh lebih dari 7,778 mm. Sedangkan untuk batas tegangan resultannya berdasarkan peraturan Allowable Stress Design (ASD) untuk dinyatakan aman adalah sebesar 149,7 MPa. Sehingga dapat disimpulkan bahwa struktur Hydraulic Lifting Machine layak digunakan dengan beban kerja maksimal 100 kg dengan angka safety factor 2,5.   Kata kunci : Crane, Metode Elemen Hingga, Tegangan Von Mises.

Statistical Modeling of Creep Rupture Data

1999 ◽  
Vol 121 (3) ◽  
pp. 264-271 ◽  
Author(s):  
R. B. Davies ◽  
R. Hales ◽  
J. C. Harman ◽  
S. R. Holdsworth
Keyword(s):  
Statistical Modeling ◽  
Rupture Strength ◽  
Creep Rupture ◽  
Confidence Limits ◽  
Creep Rupture Strength ◽  
Statistical Research ◽  
Modeling Framework ◽  
Failure Times ◽  
Rupture Data ◽  
Model Improvement

A flexible statistical modeling framework for the analysis of creep rupture data is proposed, which offers an improvement on traditional methods of deriving creep rupture strength values and confidence limits. The paper reviews a family of models that can be used to represent the trend relationship between failure times about the trend line, and examines the reliability of extrapolations. Areas of statistical research which would lead to model improvement are discussed, such as variance heterogeneity, left censoring and allowance for the cluster (cast) structure of the data.

Evaluation of Long-Term Creep Strength of Welded Joints of ASME Grades 91, 92 and 122 Type Steels

2012 ◽  
Author(s):  
Masatsugu Yaguchi ◽  
Takuaki Matsumura ◽  
Katsuaki Hoshino
Keyword(s):  
Creep Strength ◽  
Welded Joints ◽  
Rupture Strength ◽  
Reduction Factor ◽  
Creep Rupture ◽  
Creep Rupture Strength ◽  
Strength Reduction Factor ◽  
Rupture Data ◽  
Term Creep

Creep rupture data of welded joints of ASME Grades 91, 92 and 122 type steels have been collected and long-term creep rupture strength of the materials has been evaluated. Similar study was conducted by the SHC Committee in 2004 and 2005, therefore, the evaluation of the creep rupture strength was conducted with emphasis on the long-term creep rupture data obtained after the previous study, in addition to discussion of the effects of product form, welding procedure and test temperature etc. on the creep strength. Almost the same results were obtained on the welded joint of Grade 92 as the previous study, however, the master creep life equations for the welded joints of Grades 91 and 122 were lower than the previous results, especially in the case of Grade 122. Furthermore, the creep strength reduction factor obtained from 100,000 hours creep strength of welded joints and base metal was given as a function of temperature.

A Proposal for Post-Assessment Test of Long-Term Creep Rupture Strength of Grade 91 Steel

2018 ◽  
Author(s):  
Kouichi Maruyama ◽  
Nobuaki Sekido ◽  
Kyosuke Yoshimi
Keyword(s):  
Rupture Strength ◽  
Creep Rupture ◽  
Rupture Data ◽  
Data Points ◽  
Grade 91 ◽  
Term Creep ◽  
Off Time ◽  
Term Data ◽  
Grade 91 Steel

Predictions as to 105 hrs creep rupture strength of grade 91 steel have been made recently. The predictions should be verified by some means, since they are based on certain assumptions. A formula for predicting long-term creep rupture lives should correctly describe long-term data points used in its formulation. Otherwise the formula cannot properly predict further longer-term creep rupture lives. On the basis of this consideration, the predictions are examined with long-term creep rupture data of the steel. In the predictions three creep rupture databases were used: data of tube products of grade 91 steel reported in NIMS Creep Data Sheet (NIMS T91 database), data of T91 steel collected in Japan, and data of grade 91 steel collected by an ASME code committee. Short-term creep rupture data points were discarded by the following criteria for minimizing overestimation of the strength: selecting long-term data points with low activation energy (multi-region analysis), selecting data points crept at stresses lower than a half of proof stress (σ0.2/2 criterion), and selecting data points longer than 1000 hrs (cut-off time of 1000 hrs). In the case of NIMS T91 database, a time-temperature parameter (TTP) analysis of a dataset selected by the multi-region analysis can properly describe the long-term data points. However, the TTP analyses of datasets selected by the σ0.2/2 criterion and by the cut-off time of 1000 hrs from the same database overestimate the long-term data points. The different criteria for data selection have more substantial effects on predicted values of the strength of the steel than difference of the databases.

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