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Shota Urushadze - One of the best experts on this subject based on the ideXlab platform.

  • modelling and fatigue life assessment of orthotropic bridge deck details using fem
    International Journal of Fatigue, 2012
    Co-Authors: Mustafa Aygul, Mohammad Alemrani, Shota Urushadze
    Abstract:

    The fatigue life estimation of orthotropic steel bridge decks using the finite element method is most frequently associated with the application of the structural hot spot Stress Approach or the effective notch Stress Approach, rather than the traditional Nominal Stress Approach. The application of these Approaches to a welded joint with cut-out holes in orthotropic bridge decks, where it is not easy to distinguish the non-linear Stress caused by the notch at the weld toe from the Stress concentration effect emanating from the hole in the detail, was investigated. The results of the finite element calculations were compared with the results of the fatigue tests which were carried out on full-scale specimens. The results of the finite element analyses revealed that the structural hot spot Stresses obtained from the shell element models were unrealistically high when the welds were omitted. Moreover, the way in which the welds were represented had a substantial influence on the magnitude of the hot spot Stress. The results of the analysis when using the effective notch Stress Approach showed that the agreement between the estimated fatigue life using this Approach and the fatigue life obtained from the fatigue tests was good.

Berto Filippo - One of the best experts on this subject based on the ideXlab platform.

  • Local strain energy based fatigue assessment of cruciform welded joints: experimental data analysis and influence of hot-dip galvanization
    'EDP Sciences', 2018
    Co-Authors: Viespoli, Luigi Mario, Mutignani Francesco, Gulyas Gabor, Remes Heikki, Berto Filippo
    Abstract:

    Performing the fatigue assessment of a welded joint using the Notch Stress Intensity Factors [1] presents two major challenges. The first is the necessity of a precise reconstruction of the Stress field around the notch tip, thus needing an extremely refined discretization with an evident computational cost. The other, is that the dimensions of the N-SIFs and so their critical values, vary accordingly to the William’s solution [2] depending on the notch-opening angle. Consequence of this is that the mechanical properties necessary for the assessment vary as a function of the geometry treated. The research to overcome this issue has led to the use of the local Strain Energy Density [3]. The power of this parameter, used as a tool to perform fatigue assessment, consists of having a very low mesh refinement sensitivity [4], being the energy computed directly from nodal displacements and stiffness matrix [5], and having constant dimensions, so constant critical value for a given class of materials. In this paper, the local energetic method is applied to the analysis of the results of a series of tests performed on cruciform load carrying and non-load carrying specimens realized by S235 JRG2 structural steel plates. If load carrying, the fillet welded joints are made of S355 J2+N structural steel. The fatigue testing has been performed in atmosphere at room temperature in as welded condition both with and without the corrosion protective zinc layer. Particularly, the interest is focused on the influence of the zinc layer of the fatigue properties of the joint and on the capability of the local energetic Approach, confronted with the classic Nominal Stress Approach, to accurately predict the fatigue failure. To conclude, the investigation of the tests executed reveals no significant difference in the fatigue life for the coated samples, compared with the uncoated specimens and the predictions according to the IIW recommendations [6]

  • Local strain energy based fatigue assessment of cruciform welded joints
    'EDP Sciences', 2018
    Co-Authors: Viespoli, Luigi Mario, Mutignani Francesco, Gulyas Gabor, Remes Heikki, Berto Filippo
    Abstract:

    Performing the fatigue assessment of a welded joint using the Notch Stress Intensity Factors [1] presents two major challenges. The first is the necessity of a precise reconstruction of the Stress field around the notch tip, thus needing an extremely refined discretization with an evident computational cost. The other, is that the dimensions of the N-SIFs and so their critical values, vary accordingly to the William's solution [2] depending on the notch-opening angle. Consequence of this is that the mechanical properties necessary for the assessment vary as a function of the geometry treated. The research to overcome this issue has led to the use of the local Strain Energy Density [3]. The power of this parameter, used as a tool to perform fatigue assessment, consists of having a very low mesh refinement sensitivity [4], being the energy computed directly from nodal displacements and stiffness matrix [5], and having constant dimensions, so constant critical value for a given class of materials. In this paper,the local energetic method is applied to the analysis of the results of a series of tests performed on cruciform load carrying and non-load carrying specimens realized by S235 JRG2 structural steel plates. If load carrying, the fillet welded joints are made of S355 J2+N structural steel. The fatigue testing has been performed in atmosphere at room temperature in as welded condition both with and without the corrosion protective zinc layer. Particularly, the interest is focused on the influence of the zinc layer of the fatigue properties of the joint and on the capability of the local energetic Approach, confronted with the classic Nominal Stress Approach, to accurately predict the fatigue failure. To conclude, the investigation of the tests executed reveals no significant difference in the fatigue life for the coated samples, compared with the uncoated specimens and the predictions according to the IIW recommendations [6].Peer reviewe

  • Local strain energy based fatigue assessment of cruciform welded joints: experimental data analysis and influence of hot-dip galvanization
    EDP Sciences, 2018
    Co-Authors: Viespoli, Luigi Mario, Mutignani Francesco, Gulyas Gabor, Remes Heikki, Berto Filippo
    Abstract:

    Performing the fatigue assessment of a welded joint using the Notch Stress Intensity Factors [1] presents two major challenges. The first is the necessity of a precise reconstruction of the Stress field around the notch tip, thus needing an extremely refined discretization with an evident computational cost. The other, is that the dimensions of the N-SIFs and so their critical values, vary accordingly to the William’s solution [2] depending on the notch-opening angle. Consequence of this is that the mechanical properties necessary for the assessment vary as a function of the geometry treated. The research to overcome this issue has led to the use of the local Strain Energy Density [3]. The power of this parameter, used as a tool to perform fatigue assessment, consists of having a very low mesh refinement sensitivity [4], being the energy computed directly from nodal displacements and stiffness matrix [5], and having constant dimensions, so constant critical value for a given class of materials. In this paper, the local energetic method is applied to the analysis of the results of a series of tests performed on cruciform load carrying and non-load carrying specimens realized by S235 JRG2 structural steel plates. If load carrying, the fillet welded joints are made of S355 J2+N structural steel. The fatigue testing has been performed in atmosphere at room temperature in as welded condition both with and without the corrosion protective zinc layer. Particularly, the interest is focused on the influence of the zinc layer of the fatigue properties of the joint and on the capability of the local energetic Approach, confronted with the classic Nominal Stress Approach, to accurately predict the fatigue failure. To conclude, the investigation of the tests executed reveals no significant difference in the fatigue life for the coated samples, compared with the uncoated specimens and the predictions according to the IIW recommendations [6].publishedVersion© The Authors, published by EDP Sciences, 2018. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited

Tianjia Liu - One of the best experts on this subject based on the ideXlab platform.

  • assessment Approach for multiaxial fatigue damage of deck and u rib weld in steel bridge decks
    Construction and Building Materials, 2018
    Co-Authors: Yixun Wang, Tianjia Liu
    Abstract:

    Abstract Assessment Approach for multiaxial fatigue damage of deck and U-rib weld in steel bridge decks was studied. The orthotropic steel bridge deck was modelled to analyse the multiaxial Stress state of the weld under wheel load. A multiaxial fatigue loading experiment was carried out to assess the fatigue strength of deck and U-rib weld based on equivalent Stress and maximum principal Stress. The critical plane Approach which is suitable for deck-U rib welds was also established. The assessment results were then compared to those obtained by uniaxial fatigue Approach. Reasonable multiaxial fatigue principles were proposed for deck and U-rib welds in different positions. The results show that multiaxial fatigue Stress is observed in the deck-U rib weld. The shear Stress may exceed normal Stress and become the main reason for fatigue damage, thus a multiaxial fatigue Approach is necessary for fatigue damage assessment. The Nominal Stress Approach is suggested for fatigue assessment of deck and U-rib weld between diaphragms, which leads to conservative results and is more applicable to engineering practice. The critical plane Approach is suggested for fatigue assessment of deck and U-rib weld on the diaphragm considering multiaxial fatigue effects and non-proportional Stress in the weld.

Mustafa Aygul - One of the best experts on this subject based on the ideXlab platform.

  • modelling and fatigue life assessment of orthotropic bridge deck details using fem
    International Journal of Fatigue, 2012
    Co-Authors: Mustafa Aygul, Mohammad Alemrani, Shota Urushadze
    Abstract:

    The fatigue life estimation of orthotropic steel bridge decks using the finite element method is most frequently associated with the application of the structural hot spot Stress Approach or the effective notch Stress Approach, rather than the traditional Nominal Stress Approach. The application of these Approaches to a welded joint with cut-out holes in orthotropic bridge decks, where it is not easy to distinguish the non-linear Stress caused by the notch at the weld toe from the Stress concentration effect emanating from the hole in the detail, was investigated. The results of the finite element calculations were compared with the results of the fatigue tests which were carried out on full-scale specimens. The results of the finite element analyses revealed that the structural hot spot Stresses obtained from the shell element models were unrealistically high when the welds were omitted. Moreover, the way in which the welds were represented had a substantial influence on the magnitude of the hot spot Stress. The results of the analysis when using the effective notch Stress Approach showed that the agreement between the estimated fatigue life using this Approach and the fatigue life obtained from the fatigue tests was good.

Giuseppe Marulo - One of the best experts on this subject based on the ideXlab platform.

  • effects of plate stiffness on the fatigue resistance and failure location of pipe to plate welded joints under bending
    International Journal of Fatigue, 2016
    Co-Authors: Leonardo Bertini, Francesco Frendo, Giuseppe Marulo
    Abstract:

    Abstract A series of tests have been carried out using specimens made of a tube, having a thickness of t = 10  mm, joined to a plate by fillet welding. Two different kinds of specimen were employed, differing in the plate geometry (stiffness). Both kinds of specimen were tested under bending (prevalent load) and shear loading in as welded conditions. Different initiation regions for the fatigue cracks were found and significantly different fatigue resistances were obtained for the two geometries in terms of the Nominal Stress Approach (or in terms of applied load vs cycles to failure). Two local methods for the fatigue life assessment were then applied to independently analyse the experimental results: the fictitious notch rounding Approach proposed by Radaj, which is also recommended by some international standards and the more recently proposed peak Stress method, which is based on the NSIF concept. It is shown that the Nominal Stress method, which is by far the simplest method among those recommended in standards for analysing the joint under study, fails to explain the observed different endurances. On the other side, the methods based on local Stresses account for the different joint stiffness and provide a reduced scatter in the results. However, even if local Approaches, accounts for differences in the structural behaviour of the joint, the knowledge of the actual geometry of the weld need to be accounted for, in order to be able to identify the fatigue crack initiation region. For a design purpose, a safe prediction of the fatigue endurance of the joint can be obtained by all the analysed methods, if the corresponding recommended design curve is used.