Production Methods of Cold Working Joints Subjected to Fretting for Improvement of Fatigue Strength

2009 ◽  
pp. 99-99-13
Author(s):  
K. T. Waters
Keyword(s):  
Fatigue Strength ◽  
Cold Working ◽  
Production Methods

Effects of the Interference Level on the Residual Stresses in a Cold-Working Expansion Method

2013 ◽  
Vol 577-578 ◽  
pp. 329-332
Author(s):  
Marco Giglio ◽  
M. Lodi ◽  
L. Giudici
Keyword(s):  
Fatigue Strength ◽  
Residual Stresses ◽  
Fatigue Resistance ◽  
Cold Working ◽  
Expansion Method ◽  
Calculation Algorithm ◽  
Interference Level ◽  
Inner Radius ◽  
The Difference ◽  
Good Agreement

The cold-working expansion methods are extensively used in the aerospace and mechanical industry to obtain forced couplings of steel bushings into holes made on mechanical components, by means of the passage of an oversized mandrel. This work describes a calculation algorithm, able to correlate the selected interference level, as the difference between the maximum radius of the mandrel and the inner radius of the bushing, to the residual stresses expected on the hole surface. The designer, taking into account the different design choices already made, can choose the optimal interference, estimating the uncoupling resistance and the fatigue strength of forced components. Two original and different systems bushing-mandrel, in low and high interference, have been tested for determining the characteristics of fatigue resistance in the finite life part of the Wohlers diagram.The results have been compared with previously estimated data, getting a good agreement of the series. The increase of the adopted interference value determine a corresponding increase of residual stresses on the hole, both in the radial than in the circumferential direction, and an appreciable and predictable improvement of the fatigue strength of components.

Evaluation of the Fatigue Limit for Notched Parts Considering the Influences of Work Hardening and Residual Stress by Cold Working

2006 ◽  
Vol 306-308 ◽  
pp. 145-150
Author(s):  
Sheng Wu Wang ◽  
Ai Ling Wen ◽  
Shinichi Nishida ◽  
Nobusuke Hattori
Keyword(s):  
Residual Stress ◽  
Fatigue Strength ◽  
Work Hardening ◽  
Cold Working ◽  
Structural Components ◽  
Notched Specimen ◽  
Mechanical Parts ◽  
Die Pressing ◽  
Method Of Evaluation ◽  
Good Agreement

Nearly 90% of failures of machines and mechanical parts are caused at the area of stress concentrated in the structural components [1]. Hence, it is important to investigate the method of improving fatigue strength for notched parts, and method of evaluation the fatigue strength of notched parts for mechanical engineering. In this paper, the tests were carried out for improving the fatigue strength of specimens, with the hole notches that have been chamfered by die-pressing. The fatigue strength of notched part is enhanced to around 100% by die-pressing, comparing with notched specimen without die-pressing. Based on the above results, the new method for evaluation the fatigue strength with both the effects of work hardening and residual stress caused by the cold working. The estimated results by the method revealed good agreement with the tested results.

The effect of residual stresses and cold working on fatigue strength

1976 ◽  
Vol 8 (5) ◽  
pp. 529-531 ◽  
Author(s):  
S. I. Ivanov ◽  
V. F. Pavlov
Keyword(s):  
Fatigue Strength ◽  
Residual Stresses ◽  
Cold Working

The Effects of Post-Weld Cold Working Processes on the Fatigue Strength of Low Carbon Steel Resistance Spot Welds

2005 ◽  
Vol 127 (4) ◽  
pp. 718-723 ◽  
Author(s):  
R. Spitsen ◽  
D. Kim ◽  
B. Flinn ◽  
M. Ramulu ◽  
E. T. Easterbrook
Keyword(s):  
Fatigue Strength ◽  
Carbon Steel ◽  
Cold Working ◽  
Low Carbon Steel ◽  
Low Carbon ◽  
Spot Welds ◽  
Working Process ◽  
Resistance Spot ◽  
Resistance Spot Welds ◽  
Spot Welded

The investigation on the use of a post-weld cold working process to improve fatigue strength of low carbon steel resistance spot welds is presented. The cold working process generates uniform and consistent large zones of compressive residual stresses in resistance spot-welded low carbon steel structures using a specially designed indentation device. The effect of the indentation process parameters on the mechanical properties of the resistance spot weld was investigated. Comparisons of the mechanical properties and qualitative results between the as-resistance spot-welded specimens and the post-weld cold worked resistance spot-welded specimens have been made in this investigation. Fatigue testing was also conducted to evaluate the effect of post-weld cold working process on the fatigue characteristics of resistance spot welds. Results showed that a significant improvement in the fatigue strength has been achieved through the post-weld cold working process.

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