Analysis and Experiments on the Plastic Limit Load of Elbows under Combined Pressure and In-Plane Closing Bending Moment

Abstract:

This paper discusses the plastic limit load of elbows without defects and with local thinned area (LTA) in the extrados under combined pressure and in-plane closing bending moment. Finite element analysis (FEA) and experiments have been used. The results of FEA show that, for the elbows without defects, when the ratio of pressure to the limit pressure (P/PL) is smaller than 0.469, the limit moment of elbows increases with the increasing pressure; when the ratio (P/PL) is bigger than 0.469, the limit moment of elbow decreases with the increasing pressure. For the elbows with LTA, the FEA results show that with different LTA the variation of the limit load of elbows to the pressure is different. Perhaps, the limit moment of elbows always decreases with the increasing pressure. It is also likely that the limit moment of elbows increases with the increasing pressure and then decreases with the increasing pressure. The results of FEA are consistent with the experimental results. By fitting the results of FEA, the safety assessment figure for elbows under combined pressure and in-plane closing bending moment is drawn.

• Periodical: Advanced Materials Research (Volumes 774-776)
• Pages: 1090-1097
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.774-776.1090
• Online since: September 2013
• Authors: Zhi Xiang Duan, Kun Shi
• Keywords: Elbow, Experiment, Finite Element Analysis (FEA), Limit Load, Local Thinned Area, Safety Assessment

References

[1] GUO Chaxiu. Plastic Limit Loads for Surface Defect Pipes and Bends under Combined Loads of Tension, Bending, Torsion and Internal Pressure. East China University of Science and Technology. (1999).

[2] HAN Liang-hao, LIU Zeng-dian. Limit Load Analysis for Local Wall-Thinning Pipeline under Internal Pressure. PRESSURE VESSEL TECHNOLOGY, 1998, 15(4): 1-4.

[3] WANG Yan, SUN Liang, FAN De-shun. Plastic limit load analysis of elbow with local thinning. JOURNAL OF BEIJING UNIVERSITY OF CHEMICAL TECHNOLOGY, 2005, 32(1): 62-65.

[4] ASME Boiler and Pressure Vessel Code, 1992, Section III, Division 1, Nuclear Power Plant Components, ASME, New York, NY.

DOI: 10.1016/0029-5493(87)90002-1

[5] ZHEN Yi-xiang. The Study on Limit Load for a Piping with Defect of Local Wall-thining . Nanjing University of Technology, (2001).

[6] DUAN Zhi-xiang, SHEN Shi-ming. Analysis and Experiments on the Plastic Limit Load of Elbows Under In-plane Closing Bending Moments. PETRO-CHEMICAL EQUIPMENT. 2005, 34 (2): 8-10.

DOI: 10.4028/www.scientific.net/amr.774-776.1090

[7] Kitching, Zarrabi & Moore. Limit Moment for Smooth Pipe Bend under In-plane Bending. Int. J. Mech. Sci., 1979, 21: 731-738.

DOI: 10.1016/0020-7403(79)90053-5

[8] DUAN Zhi-xiang, SHEN Shi-ming. Analysis and Experiments on the Plastic Limit Load of Elbows under Internal Pressure . PRESSURE VESSEL TECHNOLOGY, 2004, 21 (8) : 1-4.

[9] Goodall, I.W. Lower Bound Limit Analysis of Curved Tubes Loaded by Combined Internal Pressure and In-Plane Bending Moment . RD/B/N4360, CEGB, (1978).