Optimal Shape Design of Axisymmetric Shells for Crack Initiation and Propagation Under Cyclic Loading

Баничук, Н. В.; Ivanova, S. Yu.; Макеев, Е. В.; Sinitsin, Alexander

doi:10.1081/sme-2000118709

Cited by 26 publications

(3 citation statements)

References 18 publications

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“…This is also reflected in the work of Banichuk and his co-researchers, who performed extensive structural optimisation studies taking into account the presence of cracks (Banichuk 1998;Banichuk et al 2005). They proposed some measures to address the associated uncertainties and incomplete design inputs (Banichuk and Neittaanmaki 2007).…”

Section: Introductionmentioning

confidence: 91%

“…In such cases the initially anticipated optimal rework profile (assuming no cracks) may not be optimum due to the presence of initial flaws. However, little attention has been paid to consider the effect of existing initial flaws on optimal shapes (Banichuk 1998;Banichuk et al 2005;Das et al 2005Das et al , 2006Banichuk and Neittaanmaki 2007;Das et al 2007;Das and Jones 2009a,b).…”

Section: Introductionmentioning

confidence: 99%

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Designing cutouts for optimum residual strength in plane structural elements

Das

Jones

2009

Int J Fract

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The paper presents a new approach for shape optimisation of structures with residual strength as the design objective. It must be emphasized that flaws are inevitably present in most structures, and hence the influence of cracks on optimised shapes needs to be investigated. Numerical simulation of cracks using the finite element method requires a very fine mesh to model the singularity at crack tip. This makes fracture calculations computationally intensive. Furthermore, for a damage tolerance based optimisation numerous cracks are to be considered along the structural boundary, and fracture analysis needs to be repeated for each crack at every iteration, thus making the whole process extremely computationally expensive for practical purpose. Moreover, the lack of information concerning crack size, orientation, and location makes the formulation of the optimisation problem difficult. As a result, little attention has been paid to date to consider fracture parameters in the optimisation objective. To address this, the paper presents a methodology for the shape optimisation of structures with strength and durability as the design objectives. In particular, the damage tolerance optimisation is illustrated via the problem of optimal design of a 'cutout in a rectangular R. Das (B) CSIRO Mathematical and Information Sciences, block under biaxial loading'. A parametric shape representation has been used to describe the problem geometry. Damage tolerance based optimisation was performed using nonlinear programming algorithms, and NE-NASTRAN was used for finite element analysis. The first order mathematical programming algorithms, viz: the Broydon-Fletcher-Goldfarb-Shanno (BFGS) and the Fletcher-Reeves (Conjugate Direction) Methods were evaluated as the potential algorithms for optimising the residual strength in the presence of flaws. Another recently developed Sequential Unconstrained Minimisation Technique (SUMT), based on an exterior penalty function method and especially suited for large problems, was also investigated for fracture based optimisation. The effects of the orientation and the number of boundary cracks on the optimal solutions were also studied. It has been shown that the residual strength optimised shapes can be different from the corresponding and commonly adopted stress optimised solution. This emphasises the need to explicitly consider residual strength as the design objective. In all cases a significant reduction in the maximum stress intensity factor was achieved with the generation of a 'near' uniform fracture critical surface. The design space near the optimal region was found to be relatively flat. This is beneficial as a significant structural performance enhancement is important rather than precise identification of the local/global optimum solution. The optimal solutions obtained using the nonlinear programming algorithms were compared against those obtained in the literature using a heuristic optimisation 123 130 R. Das, R. Jones method (Biological algorithm). The results obtained using the ...

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Section: Introductionmentioning

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Designing cutouts for optimum residual strength in plane structural elements

Das

Jones

2009

Int J Fract

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“…Optimization problems of such shells in the membrane stress state were discussed by Biezeno (1922), Struble (1956), Brown (1962) (shape of a dome with a constant thickness), Mansfield (1981), Stadler and Krishnan (1989) (natural structural shapes of shells) and Banichuk et al (2006) (constant and cyclic loadings).…”

Section: Introductionmentioning

confidence: 99%

Optimization of the geometry of thin-walled uniform-strength pressure vessel end closures

Krużelecki

Proszowski

2014

Engineering Optimization

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In this article the problem of shape and thickness optimization of uniform-strength thin-walled pressure vessel heads subjected to internal pressure is investigated. The optimal geometry of a closure, which minimizes the design objective containing both depth and capacity or both depth and volume of the material of a closure (two variants), is sought in the class of uniform-strength structures under geometrical constraints. Three types of optimization problem are considered: the optimal shape of the middle surface is sought for a prescribed wall thickness, the optimal wall thickness is sought for a prescribed shape of a closure, and the most general case when looking for both shape functions. The meridian is approximated either by the convex Bézier polynomial or by functions with free parameters. Both two-and one-arc domes are considered. The optimal solutions are obtained using the simulated annealing algorithm.

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Gravity Forces and Snow Loading

Баничук

Neittaanmäki

2009

Structural Optimization With Uncertainties

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Optimal Shape Design of Axisymmetric Shells for Crack Initiation and Propagation Under Cyclic Loading

Cited by 26 publications

References 18 publications

Designing cutouts for optimum residual strength in plane structural elements

Designing cutouts for optimum residual strength in plane structural elements

Optimization of the geometry of thin-walled uniform-strength pressure vessel end closures

Gravity Forces and Snow Loading

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