Contact Stresses in Dovetail Attachments: Finite Element Modeling

Sinclair, G. B.; Cormier, N. G.; Griffin, J. H.; Meda, G.

doi:10.1115/1.1391429

Cited by 68 publications

(21 citation statements)

References 15 publications

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“…Further demonstrations of the application of the present procedure to contact problems are available as follows: for frictionless contact with high stress concentrations and comparable indentor pro"le to that in the analytical solution of Steuermann [39], in [40]; and for contact with friction for the dovetail attachment of Figure 1, in [38]. The procedure realizes similar levels of e!ectiveness for both of these contact problems to that demonstrated here on the application in Section 4.…”

Section: Discussionsupporting

confidence: 53%

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Aggressive submodelling of stress concentrations

Cormier

Smallwood

Sinclair

et al. 1999

Int. J. Numer. Meth. Engng.

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For some "nite element analyses of stresses in engineering components, low-order elements can be preferred. This choice, however, results in slow convergence, especially at key stress concentrations. To overcome this di$culty, submodelling of stress concentrators can be employed. With submodelling, a subregion within the original global con"guration and centred on the stress concentrator of interest is analysed by itself, with a consequent reduction in computation. The more aggressive the submodelling, the smaller the subregion and the greater the computational savings. To realize such savings in actuality, it is necessary that appropriate boundary conditions be applied to the subregion. Some of these boundary conditions must be drawn from a global analysis of the original con"guration: then it is essential to ensure that such boundary conditions are determined su$ciently accurately. This paper describes a procedure for being reasonably certain that such is the case. The procedure is evaluated on a series of test problems and demonstrated on a contact application. Results show that good engineering estimates of peak stresses can be obtained even in regions of unusually high stress gradients. Furthermore, these estimates can be obtained in return for quite moderate levels of computational e!ort.R Domain decomposition is a related technique where the mesh is broken apart and sent to separate processors: see e.g. Farhat et al. [7] S There is also an approach where the region of interest is not broken out of the global grid but remeshed with a "ner mesh. This is sometimes referred to as submodelling, but really is grid gradation application. Similar experience with non-linear spring elements has lead ANSYS to make the same recommendation for problems including these elements.There are several approaches in the literature that can increase the e$ciency of "nite element analysis so that such challenges can be met. We brie#y review some of these approaches.One is to use multigrid techniques. With these techniques, a coarse grid is solved and then used as an initial guess for an iterative procedure for reducing the sti!ness matrices. An explanation of the method can be found in [2]. Some solid mechanics applications are given in [3,4]. This technique naturally combines with adaptive re"nement. In adaptive re"nement, the "nite element mesh transitions from a coarse mesh in the far "eld to a "ner mesh around the region of interest. A recent example of this combination is given in [5].Another approach is to use substructuring. In substructuring, symmetries of the mesh are exploited to reduce the size of sti!ness matrices. An explanation of the method is presented in [6, Chapter 10].R Reviews of the approach are provided in [8,9]. An example of a recent application is given in [10].A further approach, and the one of principal concern here, is submodelling. In this technique, a global grid is run and the region of greatest interest is broken out as a submodel and analysed separately with a "ner mesh. &Boundary' conditions are...

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Section: Discussionsupporting

confidence: 53%

“…Thus while there may be signi"cant stress concentrations at the edge of contact, there are no stress singularities there (see, e.g. [38]). This is so in a "nite element analysis provided one polices the contact inequalities (21) and (22).…”

Section: Applicationmentioning

confidence: 99%

Aggressive submodelling of stress concentrations

Cormier

Smallwood

Sinclair

et al. 1999

Int. J. Numer. Meth. Engng.

Self Cite

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show abstract

“…This means that it is difficult to evaluate the contact behaviour accurately with a finite element (FE) mesh of reasonable density. Sinclair et al [9] have shown that, for dovetail geometries, a local element size of 1 per cent of the corner radius is required to achieve 5 per cent stress accuracy. Hence a very fine FE model is required in order to achieve reasonable accuracy.…”

Section: Introductionmentioning

confidence: 99%

“…One of the ways in which this problem can be reduced to a manageable size is by employing a submodelling or global-local approach [10]. Computational savings with this approach are very significant and run time can be two orders of magnitude less than that of an equivalent global model [9]. In the submodelling approach, a complete model of the geometry (the global model) is analysed with relatively coarse elements, sufficient to give convergence except in the region of the stress concentration of interest (in this case the contact).…”

Section: Introductionmentioning

confidence: 99%

“…In the case of frictional contact it turns out that in many cases it may not be possible to satisfy this condition at all and it is this issue which will be addressed in the paper. Submodelling has been applied to contact problems [9], but unfortunately there appears to be very little discussion in the literature of the steps required to ensure that the outcome is successful [13].…”

Section: Introductionmentioning

confidence: 99%

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On the finite element analysis of contacting bodies using submodelling

Rajasekaran

Nowell

2005

The Journal of Strain Analysis for Engineering Design

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The implication of selecting different contact algorithms in solving a contact problem by a submodelling approach is highlighted using the example of a partial slip Cattaneo-Mindlin problem. It is shown that, by employing a penalty formulation, the state of partial slip can be incorrectly predicted as full sliding whereas a Lagrange formulation predicts the correct slipstick behaviour. The displacements along the centre-line of contact are calculated by analytical approach and compared with finite element results. It is found that the Lagrange multiplier approach predictions match the analytical results well, but prediction by the penalty formulation is sensitive to the slip tolerance selected. It is concluded that care should be exercised while using the penalty formulation for displacement-controlled problems.

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Uncertainty and global sensitivity analysis of bladed disk statics with material anisotropy and root geometry variations

Rajasekharan

Petrov

2019

Engineering Reports

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Monocrystalline blades used in gas turbines exhibit material anisotropy, and the orientation of the anisotropy axis affects the deformation of the bladed disk. Considering the orientation of the anisotropy axis as a random design parameter, the uncertainty and sensitivity analysis for static blade deformations are presented for the first time. The following two cases are analyzed using a realistic bladed disk model with friction contacts: (i) deformation of the tuned bladed disks considering the uncertainty in anisotropy orientation and variations in fir tree root geometry and (ii) deformation of mistuned bladed disks with uncertain blade crystal orientations. For efficient uncertainty and sensitivity analysis, the applicability of the following surrogate models are explored: (i) an ensemble of regression trees (random forest) and (ii) gradient‐based polynomial chaos expansion. Faster convergence in statistical characteristics has been obtained using a surrogate model compared to that obtained from finite element model based Monte Carlo simulation. From sensitivity analysis, it has been inferred that the uncertainty in static displacements of a blade in a bladed disk is primarily due to the uncertainty in anisotropy angles of that blade itself and secondarily due to the interaction of different blade anisotropy angles.

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Contact Stresses in Dovetail Attachments: Finite Element Modeling

Cited by 68 publications

References 15 publications

Aggressive submodelling of stress concentrations

Aggressive submodelling of stress concentrations

On the finite element analysis of contacting bodies using submodelling

Uncertainty and global sensitivity analysis of bladed disk statics with material anisotropy and root geometry variations

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