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Browsing by Author "Bendeich, PJ"

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Comprehensive numerical analysis of a three-pass bead-in-slot weld and its critical validation using neutron and synchrotron diffraction residual stress measurements
(Pergamon-Elsevier Science LTD, 2012-05-01) Muránsky, O; Smith, MC; Bendeich, PJ; Holden, TM; Luzin, V; Martins, RV; Edwards, L
The current paper presents a finite element simulation of the residual stress field associated with a three pass slot weld in an AISI 316LN austenitic stainless steel plate. The simulation is split into uncoupled thermal and mechanical analyses which enable a computationally less expensive solution. A dedicated welding heat source modelling tool is employed to calibrate the ellipsoidal Gaussian volumetric heat source by making use of extensive thermocouple measurements and metallographic analyses made during and after welding. The mechanical analysis employs the Lemaitre-Chaboche mixed hardening model. This captures the cyclic mechanical response which a material undergoes during the thermo-mechanical cycles imposed by the welding process. A close examination of the material behaviour at various locations in the sample during the welding process, clearly demonstrates the importance of defining the correct hardening and high temperature softening behaviour. The simulation is validated by two independent diffraction techniques. The well-established neutron diffraction technique and a very novel spiral slit X-ray synchrotron technique were used to measure the residual stress-strain field associated with the three-pass weld. The comparison between the model and the experiment reveals close agreement with no adjustable parameters and clearly validates the used modelling procedure. Crown Copyright (C) 2011 Elsevier Ltd.
Computational model development for additive manufacturing (AM) based laser cladding structural repairs of high strength metallic aerospace components
(Department of Defence, Defence Science and Technology Organisation, 2019-03) Walker, K; Cooper, T; Muránsky, O; Bendeich, PJ
Additive manufacturing is a revolutionary new technology with the potential to dramatically change the way aircraft structures and components are designed and manufactured. The technology is widely becoming a popular method to manufacture new and replacement parts, and it also offers a rapid and effective repair technology for military aircraft components. The supply lead time and/or cost of replacement for aircraft components can be substantial and additive manufacturing can provide a solution to both of these problems. DST Group is currently working with University and industry partners to develop additive manufacturing based solutions for the repair and manufacture of a range of Australian military aircraft components. Currently, there are two types of repair categories used. The first is where the repair damage is such that static and fatigue strength margins remain within accepted limits so as to restore the component geometry, function and surface finish properties (i.e. non-fracture critical). The second is where the damage is more significant and the repair itself carries load and is essential to restore static and fatigue strength margins. Advanced and high-fidelity numerical modelling is an essential element required for the design, substantiation and certification of structural repairs. This presentation describes recent work to develop that advanced computational modelling capability, particularly for predicting the residual stress profile in laser cladding repairs of high strength martensitic steel materials as used in high value, critical landing gear components.
Crack initiation and crack growth assessment of a high pressure steam chest
(Elsevier, 2011-01) Payten, WM; Wei, T; Snowden, KU; Bendeich, PJ; Law, M; Charman, D
Extensive cracking had occurred in a number of high pressure steam chests. An assessment was undertaken based on the R5 British Energy methodology to assess the components for both creep–fatigue damage initiation and crack growth analysis to determine fitness for purpose. The analysis determined that the remaining base rupture endurance life of the component was greater then 1 million hours, however, due to the start-up and shutdown ramp rates, creep–fatigue damage greater then unity has occurred leading to crack initiation in a number of locations. These cracks were confirmed during internal inspection of the steam chest. A subsequent crack growth analysis determined that the component could safely be returned to service for the expected future life of the station. © 2011, Elsevier Ltd.
Energy-based approach for the evaluation of low cycle fatigue behaviour of 2.25Cr-1Mo steel at elevated temperature
(Elsevier, 2010-08-20) Callaghan, MD; Humphries, SR; Law, M; Ho, M; Bendeich, PJ; Li, HJ; Yeung, WY
The energy-based approach for the evaluation of low cycle fatigue behaviour of 2.25Cr–1Mo steel at elevated temperature has been investigated and detailed analyses discussed. Plastic strain energy was determined per cycle and found to characterise both crack initiation and propagation to failure regimes. At cyclic stabilisation, average plastic strain energy may be used as a suitable damage parameter and correlations between experimental and predicted data determined. The fatigue toughness to failure of the material was established and the development of a fatigue toughness to crack propagation analysis is presented. © 2010, Elsevier Ltd.
High temperature remaining life cost assessment
(9th International Conference and Exhibition 2009 Operating Pressure Equipment Incorporating the AINDT Biennial Conference, 2009-08-26) Payten, WM; Bendeich, PJ; Snowden, KU
The impact of axi-symmetric boundary conditions on predicted residual stress and shrinkage in a PWR nozzle dissimilar metal weld
(American Society of Mechanical Engineers (ASME), 2012-07-15) Bendeich, PJ; Muránsky, O; Hamelin, CJ; Smith, MC; Edwards, L
Simulation of a dissimilar metal weld (DMW) in a pressurised water reactor (PWR) nozzle was performed to predict both axial distortion and hoop residual stresses in the weld. For this work a computationally efficient axi-symmetric finite element (FE) simulation was carried out rather than a full 3D analysis. Due to the 2-dimensional nature of the analysis it was necessary to examine the effect of structural restraint during welding of the main dissimilar metal weld (DMW). Traditionally this type of analysis is set up to allow one end of the structure, in this case the safe-end forging, to be unrestrained in the axial direction during welding. In reality axial expansion and subsequent contraction of deposited weld metal at the current torch position is restrained by solidified material both ahead and behind the torch. Thus the conventional axi-symmetric analysis is under-restrained in the axial direction at least during the early weld passes. The significance of this was examined by repeating the current simulation with the safe-end forging fixed to limit expansion during the heat up cycle. Contraction was however, allowed during cooling cycle. This modified boundary control method provided a significantly improved prediction of the axial distortion across the weld as well as improved prediction of through wall axial and hoop residual stresses. Copyright © 2012 The American Society of Mechanical Engineers
Investigating optimal cutting configurations for the contour method of weld residual stress measurement
(Elsevier, 2018-07) Muránsky, O; Hosseinzadeh, F; Hamelin, CJ; Traore, Y; Bendeich, PJ
The present work examines optimal cutting configurations for the measurement of weld residual stresses (WRS) using the contour method. The accuracy of a conventional, single-cut configuration that employs rigid clamping is compared with novel, double-embedded cutting configurations that rely on specimen self-constraint during cutting. Numerical analyses examine the redistribution of WRS and the development of cutting-induced plasticity (CIP) in a three-pass austenitic slot weld (NeT TG4) during the cutting procedure for each configuration. Stress intensity factor (SIF) analyses are first used as a screening tool; these analyses characterise lower stress intensities near the cutting surface when double-embedded cutting configurations are used, relative to SIF profiles from a single-cut process. The lower stress intensities indicate the development of CIP – which will ultimately affect back-calculated WRS – is less likely to occur when using an embedded configuration. The improvements observed for embedded cutting approaches are confirmed using three-dimensional finite element (FE) cutting simulations. The simulations reveal significant localised plasticity that forms in the material ligaments located between the pilot holes and the outer edges of the specimen. This plasticity is caused by WRS redistribution during the cutting process. The compressive plasticity in these material ligaments is shown to reduce the overall tensile WRS near the weld region before this region is sectioned, thereby significantly reducing the amount of CIP when cutting through the weld region at a later stage of the cutting procedure. Further improvements to the embedded cutting configuration are observed when the equilibrating compressive stresses in material ligaments are removed entirely (via sectioning) prior to sectioning of the high WRS region in the vicinity of the weld. All numerical results are validated against a series of WRS measurements performed using the contour method on a set of NeT TG4 benchmark weld specimens. © 2017 Elsevier Ltd.
Life assessment methodologies for high temperature branch pieces
(Australian Institute for Non-Destructive Testing (AINDT), 2009-08-27) Bendeich, PJ; Payten, WM
Branch pieces in high temperature steam circuits are a common feature of power generating plants both conventional and nuclear. A simple inverse code methodology based on BS1113 [1-3] exists for estimating base rupture life in cylinder to cylinder configurations (branches) under constant pressure and temperature. This does not cover the complex issue of estimating the mixed creep-fatigue effects of cycling which can have a significant influence on damage especially under the current practice of multi-shifting as utilities follow fluctuating energy markets. The current work is primarily aimed at extending the inverse code methodology for base rupture to include cycled loading due to startups and shutdowns. This is achieved under the guidelines of the R5 assessment code by the use of an analytical expression for metastable thermal stresses [4,5] and mapped thermal stress response. System loads are not considered in this work other than by the simple method suggested using the inverse code method. Only 90° non protruding branches are considered in the current work. Examples of 90° branches are examined showing the significance of cyclic loading on a variety of branch configurations. It was observed that base rupture dominates most configurations up to a "cliff edge" in thermal ramp rate followed by rapid accumulation of creep-fatigue damage at higher rates. The results are a useful aid when assessing the optimal operating conditions for individual power stations. © 2009, Australian Institute for Non-Destructive Testing (AINDT)
Neutrons for structural integrity applications of engineering components
(Australian Institute of Nuclear Science and Engineering, 2016-11-29) Paradowska, AM; Garbe, U; Reid, M; Bendeich, PJ; Law, M
The Australian Nuclear Science and Technology Organisation (ANSTO) at Lucas Heights, have two neutron instruments: KOWARI and DINGO that can be useful tool in modern welding assessment. Both instruments provide non-destructive characterisation techniques for modern materials, engineering and structural integrity investigations. The primary function of the KOWARI instrument is the determination of residual stresses within the interior of bulk engineering components and test samples, in particular for the development of modern engineering welding processes as well as post processing (e.g. post weld heat treatment, peening) and variety of structural integrity investigations. DINGO is a neutron radiography and imaging beamline used to assessing defects and dimensional tolerance of internal features engineering components well suited for thick and complex’s weldments. In this paper an overview of possibilities and recent developments on both instruments are presented.
Numerical analysis of retained residual stresses in C(T) specimen extracted from a multi-pass austenitic weld and their effect on crack growth
(Elsevier, 2014-08) Muránsky, O; Smith, MC; Bendeich, PJ; Hosseinzadeh, F; Edwards, L
Small scale fracture mechanics test specimens of austenitic stainless steel weld and heat affected zone material are often extracted from non-heat-treated weldments, which contain significant weld residual stresses. Although these stresses are substantially relaxed by the process of specimen extraction, they may still reach levels that can affect subsequent testing if the applied loads are low and deformation is elastic. Long-term creep crack growth testing is one such case, where failure to take account of retained residual stresses could result in unrealistically high measurements of creep crack growth at applied load levels equivalent to those in operating plant. This paper describes a research programme to predict the start-of-creep-test levels of retained residual stress and residual stress intensity factor in compact tension C(T) specimen blanks extracted from non-post heat-treated AISI 316 weldments. The simulations were validated using neutron diffraction and slitting residual stress measurements and stress intensity factor measurement. A pass-by-pass finite element simulation of the original weldment is performed first, and followed by extraction of the C(T) specimen blank. The predicted retained residual stresses in the specimen are compared with residual stress measurements made on similar blank using neutron diffraction, and slitting techniques. The elastic stress intensity factor due to residual stress is then evaluated on the crack plane of the C(T) specimen and compared with experimental measurements made using the slitting method. Good agreement is achieved between measurement and simulation, providing validated basis for future modelling of long term creep crack growth tests. © 2014, Elsevier Ltd.
Numerical analysis of the effect of weld-induced residual stress and plastic damage on the ballistic performance of welded steel plate
(Elsevier, 2012-06-01) Flores-Johnson, EA; Muránsky, O; Hamelin, CJ; Bendeich, PJ; Edwards, L
The current paper presents numerical analyses that elucidate the effects of post-weld residual stress and associated plastic damage on the ballistic performance of 316L austenitic steel plate. Impact simulations of an 18 mm thick plate with a centreline three-pass slot weld by hemispherical-nosed and flat-nosed projectiles are performed, with initial velocities in the range of 300-800 m/s. The numerical framework consists of three interdependent stages: (i) a weld model was developed in Abaqus/Standard and validated using two independent experimental data sets; (ii) a Johnson-Cook material model is calibrated and validated along with the shear failure fracture criterion available in Abaqus/Explicit for impact models; and (iii) the weld modelling results were transferred to an impact model built in Abaqus/Explicit, which employs the validated material and fracture models to predict the ballistic performance of welded plate. It is shown that the associated plastic strain damage accumulated during the welding process - and its distribution - has an adverse effect on the ballistic performance. It has also been determined that a fracture criterion that accounts for pre-existing damage in the weldment must be used for accurate impact analyses of welded structures. Crown Copyright (C) 2012 Published by Elsevier B.V.
Optimisation of mixed hardening material constitutive models for weld residual stress simulation using the NeT task group 1 single bead on plate benchmark problem.
(American Society of Mechanical Engineers (ASME), 2009-07-26) Smith, MC; Nadri, B; Smith, AC; Carr, DG; Bendeich, PJ; Edwards, L
A single weld bead deposited on a flat plate is a deceptively simple problem that is in practice a challenge for both measurement and prediction of weld residual stresses. Task Group 1 of the NeT collaborative network has examined this problem in an extensive programme of measurement and simulation extending from 2002 to 2008. As a result, the NeT bead on plate forms an ideal benchmark problem for the development of weld residual stress simulation techniques. One of the conclusions of NeT Task Group 1 is that the most accurate predictions of weld residual stresses in austenitic steels are achieved using mixed isotropic-kinematic material constitutive models. However, the use of these models can require both extensive materials data, and compromises in fitting either the monotonic or cyclic responses. This paper reports a detailed matrix of sensitivity studies aimed at optimising the behaviour of mixed hardening models in welding simulation, using the Lemaitre-Chaboche formulation in the ABAQUS finite element code. Predicted stresses and strains in the NeT bead on plate specimen are compared with the extensive database of residual stress measurements. Further studies examine sensitivity to the handling of high temperature inelastic strains, using a novel two-stage annealing functionality implemented within ABAQUS. The results show that, overall, the most accurate predictions are made if the Lemaitre-Chaboche parameters are optimised to fit the monotonic response over the first 2% of plastic strain. However, further improvements in prediction could be achieved if the constitutive model were capable of independently fitting both the monotonic and saturated cyclic response of the material.
Prediction and measurement of weld residual stresses in thermally aged girth-welded austenitic steel pipes
(American Society of Mechanical Engineers (ASME), 2012-07-15) Muránsky, O; Smith, MC; Bendeich, PJ; Hamelin, CJ; Edwards, L
The current paper describes finite element simulation of the complete manufacturing and service exposure history of girth-welded austenitic steel pipes fabricated from ESSHETE 1250 material for the STYLE Framework 7 project. The simulation campaign examines the impacts of prior quenching of pipe material, fabrication of closely adjacent welds, variation in mixed isotropic-kinematic hardening material constitutive models, and high temperature (650°C) service exposure (thermal ageing). The predicted residual stresses are validated using measurements made with the deep hole drilling (DHD) and incremental deep hole drilling (iDHD) techniques. Copyright © 2012 The American Society of Mechanical Engineers
Residual stresses in a welded zircaloy cold neutron source containment vessel
(Trans Tech Publications, 2014-02-01) Bendeich, PJ; Luzin, V; Law, M
Zirconium alloys are widely used in the nuclear industry because of their relative high strength, neutron transparency, resistance to high neutron-irradiation environment and corrosion resistance. One application for Zirconium alloy Zr-2.5Nb is the vacuum confinement vessel utilised in the cold neutron source of the OPAL research reactor at ANSTO. Having a total length of more the 3 meters, it is made of two sections joined using electron beam welding. The weld and the nearby regions are critical for the performance and integrity of the component and therefore understanding of the residual stresses development within the weld is important in connection to (i) evolution of fine dual phase α/b microstructure and crystallographic texture (ii) and stress-related radiation induced phenomena, such as grain growth, creep and sub-critical crack growth by delayed hydride cracking. The stresses were measured in and around an electron beam weld produced during the development of this component of the OPAL Cold Neutron Source. The effects of a large grain size in the weld were reduced by taking advantage of rotational symmetry and rotating the sample to increase the swept volume. Due to the heat-treatment after welding, the stresses were very low, less than 10% of the yield strength of the material, in both the hoop and axial directions. As a result of phase transformation effects during the welding process the final stresses are compressive in the weld, which reduces the likelihood of fracture or of hydride formation in this region. The highest stresses are in the parent material adjacent to the weld where the toughness is expected to be higher than in the weld material.
Residual stresses in Al7075 alloy laser cladded with Al-12Si alloy powder
(The Bragg Institute, Australian Nuclear Science and Technology Organisation, 2006-11-27) Durandet, Y; Bendeich, PJ; Ripley, MI; Liu, Q; Brandt, M
Compared to conventional arc-welding processes commonly used to repair aluminium (Al) components, laser-cladding involves narrower heat affected zones (HAZ), lower overall heat input and less part distortion. With the development of high power lasers, it has become an attractive technology for the refurbishment of high value added structural airframe components in commercial and military aircrafts, especially those made of hard-to-weld age hardenable Al 7xxx series alloys. Laser cladding of 6.35mm thick rolled plates of Al7075 alloy was performed at IRIS using a high power Nd:YAG Laser and an Al-128i alloy powder as the filler repair material. Residual stress profiles through the clad plate thickness were measured using neutron diffraction scattering at ANSTO. Results showed the laser cladding pattern on residual stress profiles in directions longitudinal and transverse to the plate rolling direction. © The Authors
The role of plasticity theory on the predicted residual stress field of weld structures
(Materials Science Forum, 2014-11) Muránsky, O; Hamelin, CJ; Smith, MC; Bendeich, PJ; Edwards, L
Constitutive plasticity theory is commonly applied to the numerical analysis of welds in one of three ways: using an isotropic hardening model, a kinematic hardening model, or a mixed isotropic-kinematic hardening model. The choice of model is not entirely dependent on its numerical accuracy, however, as a lack of empirical data will often necessitate the use of a specific approach. The present paper seeks to identify the accuracy of each formalism through direct comparison of the predicted and actual post-weld residual stress field developed in a three-pass 316LN stainless steel slot weldment. From these comparisons, it is clear that while the isotropic hardening model tends to noticeably over-predict and the kinematic hardening model slightly under-predict the residual post-weld stress field, the results using a mixed hardening model are quantitatively accurate. Even though the kinematic hardening model generally provides more accurate results when compared to an isotropic hardening formalism, the latter might be a more appealing choice to engineers requiring a conservative design regarding weld residual stress. © 2014, Trans Tech Publications.
Sensitivity of predicted weld residual stresses in the NeT task group 1 single bead on plate benchmark problem to finite element mesh design and heat source characteristics
(American Society of Mechanical Engineers (ASME), 2009-07-26) Bendeich, PJ; Smith, MC; Carr, DG; Edwards, L
A single weld bead deposited on a flat plate is a deceptively simple problem that is, in practice, a significant challenge for both measurement and prediction of weld residual stresses. Task Group 1 of the NeT collaborative network has examined this problem in an extensive programme of measurement and simulation extending from 2002 to 2008. Thus, the NeT bead on plate forms an ideal benchmark problem for the development of weld residual stress simulation techniques. It is often difficult to separate the influence of different analysis variables in a large collaborative study such as NeT Task Group 1. This paper examines sensitivity to mesh design, element type, and heat source characteristics in a closely controlled study using several different mesh designs, element types (both tetrahedral and hexahedral), and heat sources, but the same material constitutive model and finite element analysis code. It complements a companion paper that varies material constitutive models. A dedicated heat source modelling tool with a semi-automatic interface to the ABAQUS finite element code has been used to vary the heat source characteristics, thus facilitating rapid and controlled sensitivity studies without the need for bespoke heat source coding within ABAQUS.
Special testing equipment and validation of measurement methodologies for high temperature low cycle fatigue testing of miniature metallic specimens
(Springer Nature, 2016-02-25) Callaghan, MD; Humphries, SR; Law, M; Bendeich, PJ; Yeung, WY
A technique for high temperature low cycle fatigue testing of metallic materials has been developed, to determine fatigue behaviour through the testing of miniature specimens. The miniature specimen geometry was specifically designed, such that it could be manufactured from a small volume of material removed by chain-drilling extraction. An extensometry method to measure and control strain at the specimen shoulders during testing was adopted. This was undertaken to minimise the deleterious contact effects that can occur via extensometry attached at the gauge length of specimens, hence leading to premature failure and inaccurate fatigue data. By the application of this technique, the high temperature low cycle fatigue behaviour of 2.25Cr-1Mo steel was successfully characterised at 540 °C, under a fully reversed strain-controlled regime. The fatigue properties of the steel obtained from testing miniature specimens were shown to correlate well with existing literature for the material under comparable conditions, as determined by the testing of conventional standard-sized specimens. © 2016 Society for Experimental Mechanics
Synchrotron micro tomography reveals 3D shape of precipitates in cast magnesium alloy
(David Publishing Company, 2011-02-10) Liss, KD; Thibault, X; Li, HJ; Bendeich, PJ
Aim of the study is to compare the morphology of inclusions in magnesium alloy, investigated by both computed micro-tomography and light microscopy. Precipitates of denser material are found. The information of the light microscopic studies alone is by far insufficient to conclude on their three-dimensional shape. In contrast, the tomography reveals the full topology in all dimensions. The described inclusions are flake-like and can extend with high aspect ration into one, two or three dimensions. © 2011, David Publishing Company
Use of a simplified analytical expression for metastable thermal stress analysis and its application to creep-fatigue damage of a 2.25Cr 1Mo thick walled component
(Elsevier, 2010-02) Payten, WM; Snowden, KU; Bendeich, PJ
Thick walled pressure vessels are of considerable importance in a wide range of industries. The evaluation of stresses is necessary not only from a design point of view but also for fitness for service analysis of ageing infrastructure. The accumulation of creep–fatigue damage over time is the principal damage mechanism which will eventually lead to crack initiation in critical high temperature fossil plants. Many power stations are being subjected to two-shift operation due to changes in demand and competition from cheaper energy sources, and in the future from added carbon taxes. To assess high temperature components for creep–fatigue damage for example, under faster ramp rates and additional cycles, as a first pass it would be useful to explore the feasible operational envelope using simplified calculations. These are, however, generally not available and more complex finite element analysis is necessary. This paper uses a simplified closed form solution for metastable thermal stresses in thick walled pressure vessels. This form of solution can if necessary be used with either stress concentration factors or superposition of polynomials for more complex components derived from FEA analysis, such that the closed form solution can be used to estimate any ramp rate on the unit. In this case the ramp rates are considered to provide sufficient time to become metastable. Many existing units rely on heavy section 2.25Cr 1Mo steel (P22) pipe-work and tubing, and hence for two shifting can be subjected to high levels of cyclic strain. Based on the simplified expression developed, an operational envelope is explored for thick walled cylinders constructed using P22 steel. Creep–fatigue damage is calculated based on the R5 methodology. The analysis shows that for thick walled components with minimal stress concentrations, creep will dominate the life of the component. However, complex interaction between base rupture, onset of significant cycling, creep, and fatigue dictates the upper bound on feasible ramp rates, as a result it is possible to construct screening curves based on the effective elastic stress intensity range. © 2010, Elsevier Ltd.

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