Efficient estimate of residual stress variance using complex variable finite element methods

<p>This paper describes changes observed in bearing steel due to roller burnishing. Hydrostatic roller burnishing was selected as the most suitable method for performing roller burnishing on hardened bearing steel. The hydrostatic roller burnishing operation was applied as an additional operation after standard finishing operations. All tests were performed on samples of 100Cr6 material (EN 10132-4), and changes in the surface layer of the workpiece were then evaluated. Several simulations using finite element methods were used to obtain the best possible default parameters for the tests. The residual stress and the plastic deformation during roller burnishing were major parameters that were tested.</p>

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Simulation of Quenching in Aluminium and Comparison With Neutron Diffraction Measurements

Volume 6: Materials and Fabrication, Parts A and B ◽

10.1115/pvp2008-61491 ◽

2008 ◽

Author(s):

R. J. Dennis ◽

S. Phillips ◽

C. E. Truman ◽

A. Stiles ◽

R. Plant

Keyword(s):

Heat Treatment ◽

Residual Stress ◽

Finite Element ◽

Neutron Diffraction ◽

Residual Stresses ◽

Finite Element Methods ◽

Test Specimen ◽

Internal Diameter ◽

Linear Finite Element ◽

Quenching Process

The through life integrity of engineering components are routinely assessed using complex finite element methods. A critical input to such an assessment is an understanding of the operating environment, including service loading and temperature. Significant effort is expended identifying and understanding the effect of service loads on component integrity however there are many cases where service loading in isolation cannot account for premature failure of components during testing or in-service. A key assumption is that components in the as-built condition are often treated as stress and defect free and of nominal dimensions. This approach can however be inadequate and there are many documented cases where residual stress has influenced the in-service integrity of components. In this paper the magnitude and distribution of residual stresses are investigated in a quenched Aluminium 2014A TB test specimen. The test specimen has been specifically designed to contain design features representative of pressurised aerospace components which are quenched during manufacture. The specimen has two sections, one cylindrical (65mm internal diameter) and one oval (125mm largest internal diameter). The outer wall thickness is 10mm and the overall specimen length is 200mm with the two sections joined by a 30mm bridge section. The specimen has been subject to solution heat treatment at 505°C for five hours. Following heat treatment the specimen is rapidly quenched in cold water at 10°C with the cylindrical end entering the water first. Non-linear finite element methods have been developed to simulate the quenching process making use of user defined subroutines to enhance the standard features available in the finite element code. The accuracy of the predicted residual stresses has been assessed by comparison with neutron diffraction measurements at a range of critical locations. The work provides an extremely useful insight into how non-linear finite element methods can be successfully used to predict the residual stresses that are generated as a result of the quenching process. Where residual stresses are a potential integrity concern an understanding of the magnitude and spatial distribution of residual stress can be used to influence both the design and in-service operation of components.

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Equilibrium Profile of Modern Belted Radial Ply Tires: Its Determination and Performance Benefits

Tire Science and Technology ◽

10.2346/tire.13.410203 ◽

2013 ◽

Vol 41 (2) ◽

pp. 127-151

Author(s):

Rudolf F. Bauer

Keyword(s):

Finite Element ◽

Aspect Ratio ◽

Finite Element Methods ◽

Mathematical Analysis ◽

Internal Stresses ◽

Stress Concentrations ◽

Equilibrium Profiles ◽

Equilibrium Profile ◽

And Performance ◽

Beneficial Property

ABSTRACT The benefits of a tire's equilibrium profile have been suggested by several authors in the published literature, and mathematical procedures were developed that represented well the behavior of bias ply tires. However, for modern belted radial ply tires, and particularly those with a lower aspect ratio, the tire constructions are much more complicated and pose new problems for a mathematical analysis. Solutions to these problems are presented in this paper, and for a modern radial touring tire the equilibrium profile was calculated together with the mold profile to produce such tires. Some construction modifications were then applied to these tires to render their profiles “nonequilibrium.” Finite element methods were used to analyze for stress concentrations and deformations within all tires that did or did not conform to equilibrium profiles. Finally, tires were built and tested to verify the predictions of these analyses. From the analysis of internal stresses and deformations on inflation and loading and from the actual tire tests, the superior durability of tires with an equilibrium profile was established, and hence it is concluded that an equilibrium profile is a beneficial property of modern belted radial ply tires.

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