Yevgen Gorash

University of Strathclyde

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Donald Mackenzie

University of Strathclyde

Tugrul Comlekci

University of Strathclyde

William Dempster

University of Strathclyde

Holm Altenbach

Otto-von-Guericke University Magdeburg

Ali A. Anwar

University of Strathclyde

Haofeng Chen

University of Strathclyde

Robert Hamilton

Dartmouth–Hitchcock Medical Center

Konstantin Naumenko

Otto-von-Guericke University Magdeburg

Volodymyr Okorokov

University of Strathclyde

Ralph van Rijswick

Delft University of Technology

Cooperative Institutions

University of Strathclyde

National Technical University "Kharkiv Polytechnic Institute"

University of Edinburgh

Weir Advanced Research Centre

Otto-von-Guericke University Magdeburg

University Hospital Magdeburg

Martin Luther University Halle-Wittenberg

University of the West of Scotland

Sanden (Japan)

Joint European Torus

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Frequency Effects in Ultrasonic Fatigue Testing (UFT) of Q355B Structural Steel

Procedia Structural Integrity (2022)

Lewis Milne Yevgen Gorash Tugrul Comlekci Donald Mackenzie

Ultrasonic Fatigue Testing (UFT) is an accelerated fatigue testing method, capable of running at 20 kHz. This increased test frequency can have significant influence on the results produced for ferritic steels due to the strain rate sensitivity of the deformation mechanisms and internal heat dissipation. The aim of this investigation was to evaluate the frequency effect for the structural steel Q355B. To achieve this, the fatigue performance of the material was evaluated at 20 Hz and at 20 kHz using a test method designed to reduce the variables between the tests to just the load frequency. The discrepancy between the SN curves produced at the two frequencies was evaluated and found to match well with similar steels in literature. The effect of the ferrite content on the frequency sensitivity was evaluated, and the heat generation and fracture origin within the samples was discussed. The observations for each of these matched similar observations in literature.

10.1016/j.prostr.2022.12.079

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Citations (8)

The implications of constitutive model selection in hyperelastic parameter identification

CRC Press eBooks (2019)

Stephen John Connolly Donald Mackenzie Yevgen Gorash

Hyperelastic constitutive models are investigated and compared on their ability to predict the elastic, isothermal and rate-independent response of rubber. Constitutive model parameters are identified in an optimization problem by minimizing the difference between homogeneous experimental data and their analytical solutions. The results are presented for ten hyperelastic constitutive models over four case studies where varying extents of experimental data are used. The choice of constitutive model is found to determine how accurately experimental data is fitted, though this has different implications depending on the extent of available experimental data. With a complete data set, an accurate fit generally indicates an overall accurate prediction of the material's response. However, an accurate fit to a reduced set of experimental data may not indicate an accurate prediction of the overall response. With reduced data, accurate predictions are obtained only if the constitutive model is capable of predicting unfitted deformations and the appropriate experimental data is used.

Hyperelastic material

Identification

Ogden

10.1201/9780429324710-58

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Citations (1)

Comparative Study of FE-models and Material Data for Fatigue Life Assessments of Welded Thin-walled Cross-beam Connections

Procedia Engineering (2015)

Yevgen Gorash Tugrul Comlekci Donald Mackenzie

This paper investigates the effects of fatigue material data and finite element types on accuracy of residual life assessments under high cycle fatigue conditions. The bending of cross-beam connections is simulated in ANSYS Workbench for three different combinations of structural member shapes: RHS-RHS, RHS-angle and RHS-Channel. The weldments are made of the structural steel grades C350LO and C450LO according to the Australian Standard AS3678. The stress analysis of each weldment having specific profile dimensions under specific cyclic loading is implemented using solid and shell elements considering linear material and geometric response. The stress results are transferred to the fatigue code nCode DesignLife for the residual life prediction. For both variants of FE-mesh, the nominal stress in the weld toes is extracted by splitting the total stress into membrane and bending components and filtering out non-linear component. Considering the effects of mean stress, bending and thickness according to BS7608, failure locations and fatigue life are predicted using the Volvo method and stress integration rules from ASME Boiler & Pressure Vessel Code. Three different pairs of S-N curves (stiff for pure tension and flexible for pure bending) are considered in this work including generic seam weld curves from nCode DesignLife and FE-Fatigue and curves for the Japanese steel JIS G3106- SM490B, which is an equivalent with properties in between C350LO and C450LO. The numerical predictions are compared to the available experimental results highlighting the most preferable fatigue data input and FE-model formulation.

Fatigue limit

10.1016/j.proeng.2015.12.612

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Citations (14)

Influence of material data input on accuracy of fatigue assessments for beam weldments

PAMM (2016)

Yevgen Gorash Tugrul Comlekci Donald Mackenzie

Abstract This numerical study investigates the effects of fatigue material data and finite element types on accuracy of residual life assessments under HCF conditions. The bending of cross‐beam connections is simulated in ANSYS Workbench for three different combinations of beam profiles. The weldments are made of the high‐strength steel grades C350LO and C450LO according to AS3678. The stress analysis of weldments is implemented with solid and shell elements using linear material and geometry consideration. The stress distributions are transferred to the embedded fatigue code nCode DesignLife. For both variants of FE‐mesh, the nominal stress in the weld toes is extracted by splitting the total stress into membrane and bending components and filtering out non‐linear component. Considering the effects of bending, size and mean stress, failure locations and fatigue life are predicted using the Volvo method and rules from ASME BPV Code. Three different pairs of experimental S‐N curves (stiff and flexible) are used as material data input for fatigue analysis. The obtained numerical predictions are compared to the experimental results for shell FE‐models. The predictions using the S‐N curves for an equivalent steel demonstrate the best accuracy proving the fact that specific material data input is more effective than a generic data. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Workbench

Fatigue limit

10.1002/pamm.201610052

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Modelling of metal-to-metal seals in a pressure relief valve using advanced FE-analysis

WIT transactions on engineering sciences (2015)

Yevgen Gorash William Dempster William D. Nicholls Robert Hamilton

This study investigates the behaviour of the contact faces in the metal-tometal seal of a typical pressure relief valve.The valve geometry is simplified to an axisymmetric problem.A cylindrical nozzle, which has a valve seat on top, contacts with a disk, which is preloaded by a compressed linear spring.All the components are made of the steel AISI type 316N(L) defined using the multilinear kinematic hardening material model based on monotonic and cyclic tests at 20 • C. Analysis considerations include the effects of the Fluid Pressure Penetration (FPP) across the valve seat which exists at two different scales.There is certain limited fluid leakage through the valve seat at operational pressures, which is caused by the fluid penetrating into surface asperities at the microscale.At the macroscale, non-linear FEanalysis using the FPP technique available in ANSYS revealed that there is also a limited amount of fluid penetrating into gap.Accurate prediction of the fluid pressure profile over the valve seat is addressed in this study by considering the FPP interaction on both scales.The shape of this pressure profile introduces an additional component of the spring force, which needs to be considered to provide a reliable sealing.The analysis showed that the evolution of the profile, which is caused by the isotropic softening of the material, is significant during the cyclic operation of the valve.

Valve seat

Microscale chemistry

Relief valve

10.2495/secm150221

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Citations (5)

On cyclic yield strength in definition of limits for characterisation of fatigue and creep behaviour

Open Engineering (2017)

Yevgen Gorash Donald Mackenzie

Abstract This study proposes cyclic yield strength as a potential characteristic of safe design for structures operating under fatigue and creep conditions. Cyclic yield strength is defined on a cyclic stress-strain curve, while monotonic yield strength is defined on a monotonic curve. Both values of strengths are identified using a two-step procedure of the experimental stress-strain curves fitting with application of Ramberg-Osgood and Chaboche material models. A typical S-N curve in stress-life approach for fatigue analysis has a distinctive minimum stress lower bound, the fatigue endurance limit. Comparison of cyclic strength and fatigue limit reveals that they are approximately equal. Thus, safe fatigue design is guaranteed in the purely elastic domain defined by the cyclic yielding. A typical long-term strength curve in time-to-failure approach for creep analysis has two inflections corresponding to the cyclic and monotonic strengths. These inflections separate three domains on the long-term strength curve, which are characterised by different creep fracture modes and creep deformation mechanisms. Therefore, safe creep design is guaranteed in the linear creep domain with brittle failure mode defined by the cyclic yielding. These assumptions are confirmed using three structural steels for normal and high-temperature applications. The advantage of using cyclic yield strength for characterisation of fatigue and creep strength is a relatively quick experimental identification. The total duration of cyclic tests for a cyclic stress-strain curve identification is much less than the typical durations of fatigue and creep rupture tests at the stress levels around the cyclic yield strength.

Fatigue limit

Cyclic stress

Brittleness

10.1515/eng-2017-0019

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Citations (31)

Safe structural design for fatigue and creep using cyclic yield strength

Yevgen Gorash Donald Mackenzie

This study proposes cyclic yield strength (CYS, σ_cy) as a potential characteristic of safe design for structures operating under fatigue and creep conditions. CYS is defined on a cyclic stress-strain curve (SSC), while monotonic yield strength (MYS, σ_my) is defined on a monotonic SSC. Both values of σ_cy and σ_my are identified using a 2-step fitting procedure of the experimental SSCs using Ramberg-Osgood and Chaboche material models. A typical S-N curve in stress-life approach for fatigue analysis has a distinctive minimum stress lower bound, the fatigue endurance limit (FEL, σ_f-lim). Comparison of σ_cy and σ_f-lim reveals that they are approximately equal. Thus, safe fatigue design is guaranteed in the purely elastic domain defined by the σ_cy. A typical long-term strength (LTS) curve in time-to-failure approach for creep analysis has 2 inflections corresponding to the σ_cy and σ_my. These inflections separate 3 sections on a LTS curve, which are characterised by different creep fracture modes and creep deformation mechanisms. Thus, safe creep design is guaranteed in the linear creep domain with brittle failure mode defined by the σ_cy. These assumptions are confirmed using 3 structural steels for normal and high-temperature applications. The advantage of using σ_cy for characterisation of fatigue and creep strength is a relatively quick experimental identification. The total duration of cyclic tests for a cyclic SSC identification is much less than the typical durations of fatigue and creep rupture tests at the stress levels around the σ_cy.

Fatigue limit

Brittleness

Cyclic stress

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Citations (3)

Consideration of weld distortion throughout the identification of fatigue curve parameters using mean stress correction

Yevgen Gorash Xingguo Zhou Tugrul Comlekci Donald Mackenzie Jacob Bayyouk

The effect of weld angular distortion on fatigue test specimens cut from butt welded plates is investigated by experimental and numerical methods. The weld specimens are made of a structural steel equivalent to BS 4360 grade 50D. The SN curve obtained from experimental data is used with the fatigue post-processor nCode DesignLife for fatigue life prediction. Mean stress correction is applied using the FKM approach to address the component of bending stress induced by clamping the distorted specimen, which is constant during the fatigue test. A parameter identification procedure for the SN curve and mean stress correction is proposed. The weld SN curve evaluated using the procedure is compared to the generic weld SN curves provided in the material database of nCode DesignLife and discussed.

Distortion (music)

Curve fitting

Fatigue limit

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Application of the CEL Approach to Consider FSI for the Assessment of Leak Tightness for Elastomeric Seals

Yevgen Gorash A. Bickley Francisco Gozalo

Swellable elastomeric seal is a type of specifically engineered packer that swell upon contact with wellbore fluids. Assessment of leakage tightness is a fundamental aspect in the design of swellable packers, since they should guarantee a reliable sealing under extreme pressures of the downhole fluids. Numerical capability of the leakage pressure prediction would facilitate improvement in the packer design methodology. Previous work was focused on investigation of the non-parametric optimisation capability seeking for an optimal external shape with a goal to maximise the grip of a packer with a borehole. The verification of an optimised design was done with a dynamic FE-simulation of packer’s failure by extrusion under an excessive pressure. The downside of that verification analysis was that Abaqus/Explicit solver couldn’t implement a realistic adaptive pressure application due to changing packer disposition and contact conditions. This simulation challenge is addressed in this paper by application of the Coupled Eulerian-Lagrangian (CEL) approach in Abaqus/Explicit, which provides the ability to simulate a class of problems where the fluid-structure interaction is important.

Leakage (economics)

Solver

10.1115/pvp2018-84792

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Citations (1)

CREEP ANALYSIS FOR A WIDE STRESS RANGE BASED ON STRESS RELAXATION EXPERIMENTS

International Journal of Modern Physics B (2008)

Holm Altenbach Konstantin Naumenko Yevgen Gorash

Many materials exhibit a stress range dependent creep behavior. The power-law creep observed for a certain stress range changes to the viscous type creep if the stress value decreases. Recently published experimental data for advanced heat resistant steels indicates that the high creep exponent (in the range 5-12 for the power-law behavior) may decrease to the low value of approximately 1 within the stress range relevant for engineering structures. The aim of this paper is to confirm the stress range dependence of creep behavior based on the experimental data of stress relaxation. An extended constitutive model for the minimum creep rate is introduced to consider both the linear and the power law creep ranges. To take into account the primary creep behavior a strain hardening function is introduced. The material constants are identified for published experimental data of creep and relaxation tests for a 12% Cr steel bolting material at 500°C. The data for the minimum creep rate are well-defined only for moderate and high stress levels. To reconstruct creep rates for the low stress range the data of the stress relaxation test are applied. The results show a gradual decrease of the creep exponent with the decreasing stress level. Furthermore, they illustrate that the proposed constitutive model well describes the creep rates for a wide stress range.

Stress relaxation

Diffusion creep

Hardening (computing)

Exponent

10.1142/s0217979208050589

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Citations (27)