A simplified technique for shakedown limit load determination

Abdalla, Hany F.; Megahed, M.M.; Younan, Maher Y. A.

doi:10.1016/j.nucengdes.2006.09.033

Cited by 44 publications

(26 citation statements)

References 10 publications

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“…The fuel can is modeled as a cylindrical pressure vessel subject to constant internal pressure and a cyclic thermal gradient through the wall thickness. Data points represent FE calculations of the shakedown limit reported in [Abdalla et al 2007]. …”

Section: Construction Of Bree Diagramsmentioning

confidence: 99%

“…Although Bree diagrams can be constructed for simple geometries and loading conditions using analytical models [Bree 1967], numerical techniques are generally required [AbdelKarim 2005]. In the present study, finite element analysis (FEA) is used to apply a methodology initially reported in [Abdalla et al 2007]. The approach yields an estimate of the shakedown limit in accordance with Melan's lower bound theorem 2 .…”

Section: Construction Of Bree Diagramsmentioning

confidence: 99%

“…where σ E and C ref are the stress tensor and cyclic load amplitude for the elastic analysis and σ EP,n and C n are the corresponding values for the stress tensor and cyclic load amplitude resulting from the n-th trial calculation in the elastic-plastic analysis [Abdalla et al 2007]. If the effective (von Mises) residual 1 Subsequently, the effects of alternative loading sequences (e.g., in-phase versus out-of-phase) were also investigated [Ng and Moreton 1983].…”

Section: Construction Of Bree Diagramsmentioning

confidence: 99%

“…The computations are repeated for other load combinations until the full shakedown boundary is obtained over the domain of interest. Results obtained in [Abdalla et al 2007] for the classic Bree problem are reported in Figure 3.…”

Section: Implications Of Shakedown For Design Of Actively Cooled Thermentioning

confidence: 99%

“…The rationale is that allowing the stresses to locally exceed the yield strength of the material upon the first few cycles, with fully elastic response thereafter (shakedown), can result in substantially lighter designs. For this purpose, a simplified technique [Abdalla et al 2007] is used to conduct numerical Breelike analysis [Bree 1967] of prospective geometries and determine shakedown limits, defined by critical combinations of thermal and mechanical stresses. The geometries selected for numerical analysis are obtained from previous optimizations based on yield-limited design [Valdevit et al 2008].…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Implications of shakedown for design of actively cooled thermostructural panels

Vermaak¹,

Valdevit²,

Evans³

et al. 2011

J. Mech. Mater. Struct.

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Propulsion systems in future hypersonic vehicles will require use of actively cooled structures that can withstand extreme thermomechanical loads. Candidate designs and materials for such structures have previously been identified through conventional yield-based design principles. The present article outlines an approach that utilizes concepts of localized plasticity and shakedown under cyclic loading in the design process. For this purpose, an established computational technique is used to determine shakedown limits for prototypical cooled structures. The results are employed in a design sensitivity study. The study demonstrates that, by allowing for shakedown, structures with areal densities significantly lower than those obtained from yield-limited design can be obtained. The magnitude of the benefits depends on the specific geometry of interest, the thermomechanical boundary conditions and the constraints placed on the design.

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Section: Construction Of Bree Diagramsmentioning

confidence: 99%

Section: Construction Of Bree Diagramsmentioning

confidence: 99%

Section: Construction Of Bree Diagramsmentioning

confidence: 99%

Section: Implications Of Shakedown For Design Of Actively Cooled Thermentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Implications of shakedown for design of actively cooled thermostructural panels

Vermaak¹,

Valdevit²,

Evans³

et al. 2011

J. Mech. Mater. Struct.

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A generalised method for ratchet analysis of structures undergoing arbitrary thermo‐mechanical load histories

Lytwyn

Chen

Ponter

2015

Numerical Meth Engineering

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This version is available at https://strathprints.strath.ac.uk/52828/ Strathprints is designed to allow users to access the research output of the University of Strathclyde. Unless otherwise explicitly stated on the manuscript, Copyright © and Moral Rights for the papers on this site are retained by the individual authors and/or other copyright owners. Please check the manuscript for details of any other licences that may have been applied. You may not engage in further distribution of the material for any profitmaking activities or any commercial gain. You may freely distribute both the url (https://strathprints.strath.ac.uk/) and the content of this paper for research or private study, educational, or not-for-profit purposes without prior permission or charge.Any correspondence concerning this service should be sent to the University of Leicester, Leicester, LE1 7RH, UK AbstractA novel approach is presented based upon the Linear Matching Method framework in order to directly calculate the ratchet limit of structures subjected to arbitrary thermo-mechanical load histories. Traditionally, ratchet analysis methods have been based upon the fundamental premise of decomposing the cyclic load history into cyclic and constant components respectively, in order to assess the magnitude of additional constant loading a structure may accommodate before ratcheting occurs. The method proposed in this paper, for the first time, accurately and efficiently calculates the ratchet limit with respect to a proportional variation between the cyclic primary and secondary loads, as opposed to an additional primary load only. The method is a strain based approach and utilises a novel convergence scheme in order to calculate an approximate ratchet boundary based upon a predefined target magnitude of ratchet strain per cycle. The ratcheting failure mechanism evaluated by the method leads to less conservative ratchet boundaries compared to the traditional Bree solution. The method yields the total and plastic strain ranges as well as the ratchet strains for various levels of loading between the ratchet and limit load boundaries. Two example problems have been utilised in order to verify the proposed methodology.

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