Design of Pressure Vessels for Low-Cycle Fatigue

1962 ◽  
Vol 84 (3) ◽  
pp. 389-399 ◽  
Author(s):  
B. F. Langer
Keyword(s):  
Fatigue Strength ◽  
Pressure Vessel ◽  
Low Cycle Fatigue ◽  
Fatigue Curve ◽  
Pressure Vessels ◽  
Reduction Factor ◽  
Strength Reduction ◽  
Strength Reduction Factor ◽  
The Mean ◽  
Fatigue Evaluation

Methods are described for constructing a fatigue curve based on strain-fatigue data for use in pressure vessel design. When this curve is used, the same fatigue strength-reduction factor should be used for low-cycle as for high-cycle conditions. When evaluating the effects of combined mean and alternating stress, the fatigue strength-reduction factor should be applied to both the mean and the alternating component, but then account must be taken of the reduction in mean stress which can be produced by yielding. The complete fatigue evaluation of a pressure vessel can be a major task for the designer, but it can be omitted, or at least drastically reduced, if certain requirements can be met regarding design details, inspection, and magnitude of transients. Although the emphasis in this paper is on pressure vessel design, the same principles could be applied to any structure made of ductile metal and subjected to limited numbers of load cycles.

A Probabilistic Model of Size Effect in the Fatigue Strength of Rounds in Bending and Torsion

1980 ◽  
Vol 102 (1) ◽  
pp. 32-37
Author(s):  
C. R. Mischke
Keyword(s):  
Fatigue Strength ◽  
Probabilistic Model ◽  
Fatigue Tests ◽  
Reduction Factor ◽  
Strength Reduction ◽  
Probabilistic Design ◽  
Strength Reduction Factor ◽  
Design Procedures ◽  
Endurance Strength ◽  
The Mean

The use of a probabilistic premise to establish the relation of size to the attenuation of endurance strength in rounds, such as shafts subjected to bending or torsion is investigated. The method allows the designer to construct the appropriate expression for Marin fatigue strength reduction factor, kb, directly from fatigue tests that have been ordered. For probabilistic design procedures, the mean and standard deivation of the Marin fatigue strength reduction factor are required, and the method described allows these estimates to be made.

Tensile Plastic Instability of Axisymmetric Pressure Vessels

1998 ◽  
Vol 120 (1) ◽  
pp. 6-11 ◽  
Author(s):  
D. P. Updike ◽  
A. Kalnins
Keyword(s):  
Pressure Vessel ◽  
Detrimental Effect ◽  
Cylindrical Shells ◽  
Plastic Instability ◽  
Pressure Vessels ◽  
Reduction Factor ◽  
Test Results ◽  
Strength Reduction Factor ◽  
Burst Data ◽  
Longitudinal Welds

This paper examines the calculated pressure at a tensile plastic instability of a pressure vessel and its relationship to burst test results. It is proposed that the instability pressure be accepted as an upper bound to the pressure at which a vessel bursts, and that a strength reduction factor be used to predict the burst. The paper also presents a suitable mathematical model for the calculation of the instability pressures for thin-walled axisymmetric vessels. The proposition is tested by applying the model to a pressurized diaphragm, four cylindrical shells, and two torispherical heads, for which experimental burst data are available. It is found that the ratio of the test burst pressure to the calculated pressure at the tensile plastic instability, expressed in percent, ranges from 71 to 96 percent. The highest ratio occurs for a pressurized diaphragm with no significant defects. The lowest ratios occur for cylindrical shells with longitudinal welds, suggesting that the presence of the welds had a detrimental effect on the burst strength. These results may be useful when designing a pressure vessel with respect to its ultimate strength.

Fatigue life evaluation of an ultrafine-grained pure aluminum

2019 ◽  
Vol 234 (1) ◽  
pp. 90-104
Author(s):  
Alireza Babaei ◽  
Firooz Esmaeili-Goldarag ◽  
Hossein Jafarzadeh
Keyword(s):  
Fatigue Strength ◽  
Fatigue Behavior ◽  
Pure Aluminum ◽  
Reduction Factor ◽  
Strength Reduction ◽  
Strength Reduction Factor ◽  
Dislocation Dynamic ◽  
Constitutive Material Model ◽  
Ultrafine Grained ◽  
Cyclic Extrusion Compression

The aim of this study is an experimental and numerical investigation of the fatigue behavior of a notched ultrafine-grained pure aluminum processed by strip cyclic extrusion-compression method. In this regard, the fatigue experiments were conducted for the unprocessed and strip cyclic extrusion-compression processed specimens under various cyclic loads. In the numerical analyses, a dislocation dynamic constitutive material model which tracks the microstructure evolution was implemented for numerical estimation of the values of fatigue strength reduction factor via the volumetric approach. Considering the three-dimensional effect near the plate hole, the variation of the fatigue notch factor through the thickness of the plate was investigated and the obtained results showed that maximum fatigue strength reduction factor was occurred in the middle of the plate due to the symmetry of specimen geometry and loading condition. The investigation reveals a good agreement between the numerical and experimental lives. The results showed although the smooth processed specimens have higher fatigue strength in comparison of the unprocessed ones, the notched processed specimens have lower fatigue strength in comparison of the unprocessed ones.

346 Fatigue Strength Reduction Factor of Notched Plates subjected to Cyclic Bending Load

2001 ◽  
Vol 2001 (0) ◽  
pp. 323-324
Author(s):  
Yoshio FUKUDA ◽  
Masakazu KANOU ◽  
Satoshi SUKEGAWA ◽  
Kazuya WATANABE ◽  
Ryukichi KENJOU
Keyword(s):  
Fatigue Strength ◽  
Reduction Factor ◽  
Strength Reduction ◽  
Strength Reduction Factor ◽  
Cyclic Bending ◽  
Bending Load

Analytical Study on Fatigue Strength Reduction Factor of Small-Diameter Socket-Welded Pipe Joints

1998 ◽  
Vol 120 (2) ◽  
pp. 157-163 ◽  
Author(s):  
M. Higuchi ◽  
A. Nakagawa ◽  
K. Iida ◽  
M. Hayashi ◽  
T. Yamauchi ◽  
...  
Keyword(s):  
Residual Stress ◽  
Fatigue Strength ◽  
Welded Joints ◽  
Small Diameter ◽  
Large Change ◽  
Fatigue Tests ◽  
Reduction Factor ◽  
Strength Reduction ◽  
Strength Reduction Factor ◽  
Welded Pipe

Four-point bending and rotating bending fatigue tests were conducted on socket-welded joints made of carbon, stainless, and Cr-Mo steels for clarification of the effects of diameter, welding pass sequence and post-weld heat treatment (PWHT) on fatigue strength. The results were evaluated quantitatively. Fatigue strength of socket-welded joints was found to strongly depend on weld pass sequences in fillet welds, this being possibly due to large change in residual stress distribution at roots and toes. The effects of residual stress were thus examined quantitatively by comparison of fatigue strength of PWHT stress-free specimens with that of as-welded specimens. By the modified Goodman’s method, the lowest S-N curve corresponding to maximum tensile residual stress and the highest S-N curve corresponding to maximum compression residual stress were obtained for different steels and diameters. Conventional S-N data of socket-welded joints were situated between these two limiting curves. Based on the lowest curve, fatigue strength reduction factors of socket-welded joints were proposed.

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