0
Research Papers: NDE

A Fully Implicit, Lower Bound, Multi-Axial Solution Strategy for Direct Ratchet Boundary Evaluation: Theoretical Development

[+] Author and Article Information
Alan Jappy

e-mail: alan.jappy@strath.ac.uk

Donald Mackenzie

e-mail: d.mackenzie@strath.ac.uk

Haofeng Chen

e-mail: haofeng.chen@strath.ac.uk

Department of Mechanical and Aerospace
Engineering,
University of Strathclyde,
Glasgow G1 1XQ, UK

Contributed by the Pressure Vessel and Piping Division of ASME for publication in the Journal of Pressure Vessel Technology. Manuscript received August 20, 2012; final manuscript received April 9, 2013; published online August 26, 2013. Assoc. Editor: Wolf Reinhardt.

J. Pressure Vessel Technol 135(5), 051202 (Aug 26, 2013) (11 pages) Paper No: PVT-12-1132; doi: 10.1115/1.4024449 History: Received August 20, 2012; Revised April 09, 2013

Ensuring sufficient safety against ratchet is a fundamental requirement in pressure vessel design. Determining the ratchet boundary can prove difficult and computationally expensive when using a full elastic–plastic finite element analysis and a number of direct methods have been proposed that overcome the difficulties associated with ratchet boundary evaluation. Here, a new approach based on fully implicit finite element methods, similar to conventional elastic–plastic methods, is presented. The method utilizes a two-stage procedure. The first stage determines the cyclic stress state, which can include a varying residual stress component, by repeatedly converging on the solution for the different loads by superposition of elastic stress solutions using a modified elastic–plastic solution. The second stage calculates the constant loads which can be added to the steady cycle while ensuring the equivalent stresses remain below a modified yield strength. During stage 2 the modified yield strength is updated throughout the analysis, thus satisfying Melan's lower bound ratchet theorem. This is achieved utilizing the same elastic plastic model as the first stage, and a modified radial return method. The proposed methods are shown to provide better agreement with upper bound ratchet methods than other lower bound ratchet methods, however limitations in these are identified and discussed.

FIGURES IN THIS ARTICLE
<>
Copyright © 2013 by ASME
Topics: Stress , Cycles
Your Session has timed out. Please sign back in to continue.

References

Figures

Grahic Jump Location
Fig. 1

Bree diagram with inset stress–strain responses

Grahic Jump Location
Fig. 2

Elastic residual and loaded stress vectors below yield

Grahic Jump Location
Fig. 3

Elastic residual and loaded stress vectors above yield

Grahic Jump Location
Fig. 4

Calculation of the maximum allowable constant equivalent stress

Grahic Jump Location
Fig. 5

Pictorial representation of stage 2, X ≤ 1

Grahic Jump Location
Fig. 6

Pictorial representation of stage 2, X > 1

Grahic Jump Location
Fig. 10

Residual stress, |p¯|, at a cyclic temperature (Δθ/100) = 0.5

Grahic Jump Location
Fig. 11

Residual stress, |p¯|, at a cyclic temperature (Δθ/100) = 1.0

Grahic Jump Location
Fig. 12

Residual stress, |p¯|, at a cyclic temperature (Δθ/100) = 2.5

Grahic Jump Location
Fig. 8

Ratchet boundary plate with hole

Grahic Jump Location
Fig. 9

Modified yield strength (Δθ/100 = 0.5): left method 2; right hybrid method

Tables

Errata

Discussions

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In