Research on the Conversion Relationship for Three-Point Bending Specimen With Fixed Constraints in the Large Deformation Stage

2019 ◽  
Vol 141 (6) ◽  
Author(s):  
Hai-Yang Yu ◽  
Guo-Yan Zhou ◽  
Fa-Kun Zhuang
Keyword(s):  
Large Deformation ◽  
Creep Test ◽  
Geometric Parameters ◽  
Test Method ◽  
Three Point Bending ◽  
Deformation Stage ◽  
Creep Stress ◽  
Uniaxial Creep ◽  
Conversion Coefficients ◽  
Beam Bending

Abstract In this study, based on the rod tensile model, a conversion relationship between three-point bending specimen with fixed constraints (TPBSF) and uniaxial creep data in the large deformation stage is defined by the reference stress method. Using finite element method, conversion coefficients are determined. Then it is verified by the creep test data of A7N01 at 350 °C (Zhuang, F. K., 2014, “Research on Creep Test Method of Small Specimen Based on Beam Bending Theory,” Ph.D. thesis, East China University of Science and Technology, Shanghai, China). The results show that creep stress exponent n is the same, but creep constant B obtained by rod tensile model is much closer to uniaxial creep than beam bending model. Finally, effects of geometric parameters and friction on conversion coefficients are investigated. On this basis, the specimen cross section aspect ratio greater than 1 and the indenter radius larger than 1 mm are recommended to minimize the influence of TPBSF geometric parameters on conversion coefficients. The influence of friction on conversion coefficients can be negligible.

Analysis and Design of a Small, Two-Bar Creep Test Specimen

2013 ◽  
Vol 135 (4) ◽  
Author(s):  
Tom H. Hyde ◽  
Balhassn S. M. Ali ◽  
Wei Sun
Keyword(s):  
Finite Element ◽  
Creep Strain ◽  
Creep Test ◽  
Test Specimen ◽  
Test Method ◽  
Finite Element Analyses ◽  
Analysis And Design ◽  
Specimen Type ◽  
Reference Stress ◽  
Uniaxial Creep

In this paper, a new small-sized (two-bar) specimen type, which is suitable for use in obtaining both uniaxial creep strain and creep rupture life data, is described. The specimen has a simple geometry and can be conveniently machined and loaded (through pin-connections) for testing. Conversion relationships between the applied load and the corresponding uniaxial stress, and between the measured load-line deformations and the corresponding uniaxial minimum creep strain rate, have been obtained, based on the reference stress method (RSM), in conjunction with finite element analyses. Using finite element analyses the effects of the specimen dimensions on reference stress parameters have been investigated. On this basis, specimen dimension ratio ranges are recommended. The effects of friction, between the loading pins and the specimen surfaces, on the specimen failure time, are also investigated. Test results obtained from two-bar specimen tests and from corresponding uniaxial specimen tests, for a P91 steel at 600 °C, are used to validate the test method. These results demonstrated that the specimen type is capable of producing full uniaxial creep strain curves. The advantages of this new, small, creep test specimen, for determining uniaxial creep data, are discussed and recommendations for future research are given.

Creep Properties Assessment of Materials by a Small Cantilever Beam Specimen

2018 ◽  
Author(s):  
Fakun Zhuang ◽  
Shantung Tu ◽  
Guoshan Xie ◽  
Shanshan Shao ◽  
Luowei Cao
Keyword(s):  
Cantilever Beam ◽  
Creep Test ◽  
Uniaxial Stress ◽  
Test Method ◽  
Creep Model ◽  
Beam Specimen ◽  
Secondary Creep ◽  
Creep Tests ◽  
Creep Properties ◽  
Uniaxial Creep

Small specimen creep test techniques have been widely applied in the creep properties assessment of materials for the equipment in-service. In order to acquire the creep data accurately and conveniently, the creep test method with small cantilever beam specimens is proposed. On the basis of Norton-Bailey creep law, analytical creep model for the cantilever beam specimen is derived. With this model, the load can be converted to equivalent uniaxial stress and the displacement rate can be converted to equivalent uniaxial strain rate. The creep properties of Cr-Mo steel are assessed by the cantilever beam specimens creep tests. And the creep parameters are evaluated, which are compared to the uniaxial creep parameters. The results show that parameters obtained from the cantilever beam tests correspond reasonably well with those from uniaxial tests. It proves that the primary and secondary creep properties can be assessed by the cantilever beam specimen tests.

A Basis for Selecting the Most Appropriate Small Specimen Creep Test Type

2014 ◽  
Vol 136 (2) ◽  
Author(s):  
T. H. Hyde ◽  
C. J. Hyde ◽  
W. Sun
Keyword(s):  
Creep Test ◽  
Nuclear Power ◽  
Bulk Material ◽  
Operating Conditions ◽  
Test Method ◽  
Small Ring ◽  
Test Type ◽  
Advantages And Disadvantages ◽  
Uniaxial Creep ◽  
Aero Engines

Many components in conventional and nuclear power plant, aero-engines, chemical plant etc., operate at temperatures which are high enough for creep to occur. These include plain pipes, pipe bends, branched pipes etc., the manufacture of such components may also require welds to be inserted in them. In most cases, only nominal operating conditions (i.e., pressure, temperatures, system load, etc.) are known and hence precise life predictions are not possible. Also, the proportion of life consumed will vary from position to position within a component and the plant. Hence, nondestructive techniques are adopted to assist in making decisions on whether to repair, continue operating or scrap certain components. One such approach is to use scoop samples removed from the components to make small creep test specimens, i.e., sub-size uniaxial creep test specimens, impression creep test specimens, small punch creep test specimens, and small ring (circular or elliptical) creep test specimens. Each specimen type has its own unique advantages and disadvantages and it may not be obvious which one is the most appropriate test method to use. This paper gives a brief description of each specimen and associated test type and describes their practical limitations. The suitability of each of the methods for determining “bulk” material properties is described and it is shown that an appropriate test type can be chosen.

A Basis for Selecting the Most Appropriate Small Specimen Creep Test Type

2012 ◽  
Author(s):  
T. H. Hyde ◽  
C. J. Hyde ◽  
W. Sun
Keyword(s):  
Creep Test ◽  
Nuclear Power ◽  
Bulk Material ◽  
Operating Conditions ◽  
Test Method ◽  
Small Ring ◽  
Test Type ◽  
Advantages And Disadvantages ◽  
Uniaxial Creep ◽  
Aero Engines

Many components in conventional and nuclear power plant, aero-engines, chemical plant etc, operate at temperatures which are high enough for creep to occur. These include plain pipes, pipe bends, branched pipes etc; the manufacture of such components may also require welds to be inserted in them. In most cases, only nominal operating conditions (i.e. pressure, temperatures, system load etc) are known and hence precise life predictions are not possible. Also, the proportion of life consumed will vary from position to position within a component and the plant. Hence, non-destructive techniques are adopted to assist in making decisions on whether to repair, continue operating or scrap certain components. One such approach is to use scoop samples removed from the components to make small creep test specimens, i.e., sub-size uniaxial creep test specimens, impression creep test specimens, small punch creep test specimens and small ring creep test specimens. Each specimen type has its own unique advantages and disadvantages and it may not be obvious which one is the most appropriate test method to use. This paper gives a brief description of each specimen and associated test type and describes their practical limitations. The suitability of each of the methods for determining “bulk” material properties is described and it is shown that an appropriate test type can be chosen.

Research on Creep Behavior of Three-Point Bending Specimen with Fixed Constraints at the Large Deformation Stage

2021 ◽  
Author(s):  
Xiao Han ◽  
Haiyang Yu ◽  
Guo-Yan Zhou ◽  
Fakun Zhuang ◽  
Shan-Tung Tu
Keyword(s):  
Aluminum Alloy ◽  
Large Deformation ◽  
Creep Deformation ◽  
Deformation Theory ◽  
Equivalent Stress ◽  
Small Deformation ◽  
Test Technique ◽  
Three Point Bending ◽  
Deformation Stage ◽  
General Deformation

Abstract Three-point bending specimen with fixed constraints (TPBSF) is a novel small specimen test technique, which can simultaneously obtain creep deformation and creep fracture data. However, the current researches are only focused on the small deformation theoretical analysis, which is contrary to the actual experiment results. In this study, the general deformation theory was introduced to analyze creep deformation behavior of TPBSF at the large deformation stage. Based on this theory, the equivalent stress and strain were analyzed. Then the feasibility and accuracy were verified by comparing with the experimental data of A7N01 aluminum alloy at 380 ?. The results show that the regressed creep parameters agree well with those from the uniaxial ones. It can be found that the equivalent stress obtained by the general deformation theory can be well used to life prediction analysis of A7N01 aluminum alloy.

Modelling and Data Interpretation of Small Punch Creep Testing

2011 ◽  
Author(s):  
R. Li ◽  
T. H. Hyde ◽  
W. Sun ◽  
B. Dogan
Keyword(s):  
Large Deformation ◽  
Test Data ◽  
Creep Test ◽  
Creep Model ◽  
Test Results ◽  
Creep Tests ◽  
Creep Properties ◽  
Small Punch ◽  
Draft Code ◽  
Uniaxial Creep

The small punch testing (SPT) technique has been proposed for use in determining the creep properties of materials for which only a very small volume of material is available. A draft code of practice on SPT has been produced. However it is not, as yet, generally accepted that the data obtained from small punch tests can be directly related to those which would be obtained from conventional uniaxial creep tests. For this reason, the development of techniques suitable for the interpretation of SPT data has become very important. In this paper, a set of uniaxial creep test data has been characterised in such a way as to gain an improved understanding of the correlation between the data from small punch tests and corresponding uniaxial creep tests. Finite element (FE) analyses of small punch creep tests, using a damage mechanics based creep model, have been performed. The effect of large deformation on the determination of material properties for a creep damage model, has been investigated to take into account the large deformation nature of small punch tests. An equivalent stress, σeq, proposed by the draft code, was used to relate the SPT results to the corresponding uniaxial creep test results. A preliminary assessment of the use of small punch test results, in determining creep properties, has been presented, which includes comparisons of the failure life and equivalent minimum strain rate results obtained from SPTs with the corresponding uniaxial creep test data. Future work related to the interpretation of SPT is briefly addressed.

A new Creep Test Method for Asphalt

2010 ◽  
Vol 11 (3) ◽  
pp. 969-991 ◽  
Author(s):  
Xiaoming Huang ◽  
yuqing Zhang
Keyword(s):  
Creep Test ◽  
Test Method
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