Design rules for autofrettage of an aluminium valve body

Sellen, Stephan; Maas, Stefan; Andreas, Thomas; Plapper, Peter; Zürbes, Arno; Becker, Daniel

doi:10.1111/ffe.12328

Cited by 8 publications

(13 citation statements)

References 23 publications

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“…These initial cracks were arrested during propagation due to a barrier of compressive residual stresses induced by autofrettage. Similar crack arrest effects were also observed in studies of diesel‐engine injection tubes . Accurate determination of crack propagation time in the presence of these phenomena requires application of fracture mechanics methods.…”

Section: Introductionsupporting

confidence: 63%

High cycle fatigue analysis in the presence of autofrettage compressive residual stress

Okorokov

Mackenzie

Gorash

et al. 2018

Fatigue Fract Eng Mat Struct

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An experimental and numerical investigation of the effect of residual compressive stress on the high cycle fatigue life of notched low carbon steel test specimens is presented. Experimentally determined cyclic stress strain curves for S355 low carbon steel are utilized in a finite element analysis plasticity modelling framework incorporating a new cyclic plasticity material model representative of cyclic hardening and softening, cyclic mean stress relaxation, and ratcheting behaviors. Fatigue test results are presented for standard tensile fatigue test specimens and novel double notch specimens. Double notch specimens are tested with and without compressive residual stress prior‐induced through tensile overload. It is shown that cyclic plasticity phenomena have a significant influence on the induced residual stress distribution and also on material behavior when fatigue tested in the high cycle regime. It is observed that higher initial compressive residual stresses magnitude does not necessarily lead to a longer fatigue life. Finite element analysis using the new cyclic plasticity material model shows this behavior is due to combined residual stress redistribution under fatigue test cyclic loading and cyclic hardening effects. A fatigue life methodology based on the stress‐life approach augmented by a critical distance method is proposed and shown to give good agreement with experimental results for test specimens with no induced residual stress. The results obtained for specimens with induced residual stress are more conservative, but the degree of conservatism is significantly lower than that in the conventional stress life approach. The proposed methodology is therefore suitable for analysis and design assessment of components with pre‐service induced compressive residual stress, such as autofrettaged pressure components.

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Section: Introductionsupporting

confidence: 63%

High cycle fatigue analysis in the presence of autofrettage compressive residual stress

Okorokov

Mackenzie

Gorash

et al. 2018

Fatigue Fract Eng Mat Struct

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show abstract

“…A complete plasticity model and the superposition method for crack propagation did not show any significant difference in the calculated results, which were verified by experiments. Sellen et al 19 showed how the autofrettage process of an aluminium (EN AW 6082 T6) valve body can improve the fatigue life of a 90°‐bore intersection. This design methodology is applied and tested in these experiments.…”

Section: State Of the Artmentioning

confidence: 99%

“…Using linear fracture mechanics, Greuling et al 8,21 and Schön and Seeger 5 described the crack closure effect, and Sellen et al 19 used it to define the crack growth limit of an aluminium component. In linear elastic fracture mechanics, macroscopic crack growth is not given under cyclic load if the effective cyclic threshold stress intensity range Δ K eff is equal or less than the theoretical threshold stress intensity range Δ K th .…”

Section: State Of the Artmentioning

confidence: 99%

Numerical determination and experimental verification of the optimum autofrettage pressure for a complex aluminium high‐pressure valve to foster crack closure

Repplinger

Sellen²,

Kędziora

et al. 2020

Fatigue Fract Eng Mat Struct

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The determination of the optimum autofrettage pressure enables a clear improvement of the fatigue life for an internally highly pressurized component. The autofrettage process induces residual compressive stress after the release of a single static overload pressure, leading to plastic deformation at the inner wall whereas the outer part is only elastically stressed. This autofrettage pressure is clearly above the subsequent pulsating operating pressure range. Due to the complex geometry of the aluminium valve body, a detailed elastic–plastic finite element analysis is used to determine the critical area and the optimum autofrettage pressure. Based on an experimental stress–strain curve, three important load steps are simulated in a non‐linear way. The FKM guideline is used to assess fatigue life and crack initiation with detailed subsequent experimental verification. Even if small cracks occur, residual compressive stresses prohibit crack growth (nonpropagating crack), which can be analytically verified by fracture mechanical considerations (crack closure effect).

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“…The study has shown the new method of the estimation of the optimum autofrettage pressure for geometrically complex parts. The procedure is less sensitive for a biassed assessment, as presented by the author [10]. The method can be automated, as shown in the presented example of ANSYS Workbench and nCode.…”

Section: Discussionmentioning

confidence: 94%

“…A recent study [10] has been conducted using the nonlinear finite element method for the automotive hydrogen valve, and the author used iterative method for estimation of the autofrettage pressure for an aluminum valve body.…”

Section: Review Of Literaturementioning

confidence: 99%

Optimum Autofrettage Pressure of Hydrogen Valve Using Finite Element and Fatigue Analysis

Kędziora

Cao²

2020

ENG

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The presented article shows an estimation method of optimum autofrettage pressure taking into consideration subsequent cyclic loading. An autofrettage process is used in pressure vessel applications for strength improvement. The process relies on applying massive pressure that causes internal portions of the part to yield plastically, resulting in internal compressive residual stresses when pressure is released. Later applied working pressure (much lower than autofrettage pressure) creates stress reduced by the residual compressive stress improving the structural performance of the pressure vessels. The optimum autofrettage pressure is a load that maximizes the fatigue life of the structure at the working load. The estimation method of that pressure of a hydrogen valve is the subject of the presented work. Finite element and fatigue analyses were employed to investigate the presented problem. An automated model was developed to analyze the design for various autofrettage pressures. As the results of the procedure, the optimum autofrettage pressure is determined. The research has shown that the developed method can profitably investigate the complex parts giving the autofrettage load that maximizes the fatigue life. The findings suggest that the technique can be applied to a large group of products subjected to the autofrettage process.

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Design rules for autofrettage of an aluminium valve body

Cited by 8 publications

References 23 publications

High cycle fatigue analysis in the presence of autofrettage compressive residual stress

High cycle fatigue analysis in the presence of autofrettage compressive residual stress

Numerical determination and experimental verification of the optimum autofrettage pressure for a complex aluminium high‐pressure valve to foster crack closure

Optimum Autofrettage Pressure of Hydrogen Valve Using Finite Element and Fatigue Analysis

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