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Sabrina Vantadori - One of the best experts on this subject based on the ideXlab platform.
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Novel non-linear relationship to evaluate the Critical Plane orientation
International Journal of Fatigue, 2019Co-Authors: Ashish Aeran, Sabrina Vantadori, Andrea Carpinteri, Sudath C. Siriwardane, Daniela ScorzaAbstract:Abstract Damage in offshore structures is mainly due to fatigue multiaxial stress state at structural joints, and fatigue strength assessment of such joints through the Critical-Plane criterion is well-accepted by the scientific community. A novel relationship to estimate the Critical Plane orientation is proposed in the present paper. Such a relationship is implemented in the stress-based Critical-Plane criterion by Carpinteri et al., which is applicable to any metallic material under multiaxial constant amplitude fatigue loading. Fatigue life of specimens made of different metallic materials is herein evaluated by using such a criterion. The experimental fatigue life of each specimen examined is compared with the analytical one. The relationship above seems to be a useful tool for estimations of fatigue life under multiaxial loading.
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Hot-spot localisation according to the Critical Plane-based approach
International Journal of Fatigue, 2018Co-Authors: Sabrina Vantadori, Giovanni Fortese, Felipe Giordani, Ignacio IturriozAbstract:Abstract The tubular welded joints in H-shaped structural components of agricultural sprayers are responsible for failure and the localisation of hot-spots is very important in multiaxial fatigue assessment of such components. Therefore, the purpose of the present paper is to develop a novel approach both to localize hot-spots in tubular welded joints and to estimate the initial crack growth direction. Such an approach is based on the application of the hot-spot stress approach together with the multiaxial Critical Plane-based criterion proposed by Carpinteri et al. Comparison between experimental data and numerical results has shown a satisfactory agreement in terms of both hot-spots localisation and initial crack growth direction evaluation.
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early fretting crack orientation by using the Critical Plane approach
International Journal of Fatigue, 2018Co-Authors: Sabrina Vantadori, Giovanni Fortese, Gabriel Magalhaes Juvenal Almeida, Geovana Callasans Veras Pessoa, J.a. AraújoAbstract:Abstract In the present paper, the novel Critical direction method by Araujo et al. and the multiaxial Critical Plane-based criterion by Carpinteri et al. are combined together to estimate early crack orientation in configurations involving high stress gradients, as fretting fatigue configurations. More precisely, the first method is used to compute the input data for the second one, in terms of normal and shear stresses over a line with a characteristic length. The experimental data herein analysed are related to an Al7050 T7451 aluminium alloy, the fretting tests related to a cylinder-on-Plane configuration being performed by the Research Group of Fatigue, Fracture and Materials at the University of Brasilia. Results show that the estimated values of the crack initiation Plane fall in the interval defined by the mean experimental values and the standard deviation for each test configuration examined.
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estimation of fatigue life under multiaxial loading by varying the Critical Plane orientation
International Journal of Fatigue, 2017Co-Authors: Andrea Carpinteri, Marta Kurek, Tadeusz łagoda, Sabrina VantadoriAbstract:Abstract Fatigue life of different metallic materials under multiaxial loading is evaluated by employing the Critical Plane-based criterion proposed by some of the present authors. According to such a criterion, the multiaxial fatigue strength is assessed through an equivalent stress expressed by a linear combination of the normal stress amplitude and the shear stress amplitude acting on the Critical Plane. The Critical Plane orientation is determined by a novel expression, which is a non-linear function of the ratio between the fully reversed stress fatigue limits (τaf,−1/σaf,−1), and such an expression can be employed for any value of this ratio. Some experimental fatigue life data related to smooth specimens under combined normal loading (tension or bending) and torsion loading are compared with the theoretical estimations deduced through the above criterion.
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Estimation of fatigue strength under multiaxial cyclic loading by varying the Critical Plane orientation
Fracture and Structural Integrity, 2016Co-Authors: Marta Kurek, Andrea Carpinteri, Tadeusz Agoda, Sabrina VantadoriAbstract:The main purpose of this paper is to examine the influence of the Critical Plane orientation on the estimated fatigue strength of metals under multiaxial loading. The algorithm employed to evaluate fatigue strength implements the criterion of maximum normal and shear stress on a suitable damage Plane (Critical Plane). The angle beta defining the Critical Plane orientation is measured with respect to the direction that maximises the applied normal stress. Eleven (11) structural materials under combined bending and torsion cyclic loading are examined. For each analysed material, the value of beta angle is selected so that the value of the scatter, defined by a root-mean-square value, is minimum. On the basis of such a calculation, an empirical expression for beta is proposed, that takes into account the values of bending and torsion fatigue strengths at a reference number of loading cycles. According to such an expression, beta is constant for a given material.
Andrea Carpinteri - One of the best experts on this subject based on the ideXlab platform.
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Novel non-linear relationship to evaluate the Critical Plane orientation
International Journal of Fatigue, 2019Co-Authors: Ashish Aeran, Sabrina Vantadori, Andrea Carpinteri, Sudath C. Siriwardane, Daniela ScorzaAbstract:Abstract Damage in offshore structures is mainly due to fatigue multiaxial stress state at structural joints, and fatigue strength assessment of such joints through the Critical-Plane criterion is well-accepted by the scientific community. A novel relationship to estimate the Critical Plane orientation is proposed in the present paper. Such a relationship is implemented in the stress-based Critical-Plane criterion by Carpinteri et al., which is applicable to any metallic material under multiaxial constant amplitude fatigue loading. Fatigue life of specimens made of different metallic materials is herein evaluated by using such a criterion. The experimental fatigue life of each specimen examined is compared with the analytical one. The relationship above seems to be a useful tool for estimations of fatigue life under multiaxial loading.
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Multiaxial Fatigue Damage Assessment of Welded Connections in Railway Steel Bridge using Critical Plane Approach
Procedia Engineering, 2018Co-Authors: Praveen K R, Andrea Spagnoli, S.s. Mishra, Prasad Babu, Andrea CarpinteriAbstract:Abstract As the number of heavy railway traffic load increased, concern over the accurate and actual fatigue damage of the bridge is intensified. Especially for bridges which were designed for light traffic load. The fatigue damage assessment of steel bridge connections is usually based on notion of uniaxial S-N curves given in the codes of practice. Until now, there is no consensus on a method which can precisely consider non-proportional multiaxial loading. The objective of this paper is to examine the applicability and appropriateness of the Critical Plane approach-based C-S criterion to perform the fatigue damage assessment in welded connections in railway steel bridge. A regular U trough railway steel bridge is analyzed using finite element software ANSYS 17.2 for standard railway traffic. The averaged principal stress directions determined through appropriate weight functions are used to orient the Critical Plane. Prediction of fatigue damage is performed through an equivalent stress represented by a quadratic combination of the normal and the shear stress components acting on the Critical Plane. Applicability of the C-S criterion is studied by assessing the fatigue damage of Critical welded connections and comparing with the λ - coefficient and cumulative damage method calculated according to Eurocode EN1993-1-9.
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estimation of fatigue life under multiaxial loading by varying the Critical Plane orientation
International Journal of Fatigue, 2017Co-Authors: Andrea Carpinteri, Marta Kurek, Tadeusz łagoda, Sabrina VantadoriAbstract:Abstract Fatigue life of different metallic materials under multiaxial loading is evaluated by employing the Critical Plane-based criterion proposed by some of the present authors. According to such a criterion, the multiaxial fatigue strength is assessed through an equivalent stress expressed by a linear combination of the normal stress amplitude and the shear stress amplitude acting on the Critical Plane. The Critical Plane orientation is determined by a novel expression, which is a non-linear function of the ratio between the fully reversed stress fatigue limits (τaf,−1/σaf,−1), and such an expression can be employed for any value of this ratio. Some experimental fatigue life data related to smooth specimens under combined normal loading (tension or bending) and torsion loading are compared with the theoretical estimations deduced through the above criterion.
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Estimation of fatigue strength under multiaxial cyclic loading by varying the Critical Plane orientation
Fracture and Structural Integrity, 2016Co-Authors: Marta Kurek, Andrea Carpinteri, Tadeusz Agoda, Sabrina VantadoriAbstract:The main purpose of this paper is to examine the influence of the Critical Plane orientation on the estimated fatigue strength of metals under multiaxial loading. The algorithm employed to evaluate fatigue strength implements the criterion of maximum normal and shear stress on a suitable damage Plane (Critical Plane). The angle beta defining the Critical Plane orientation is measured with respect to the direction that maximises the applied normal stress. Eleven (11) structural materials under combined bending and torsion cyclic loading are examined. For each analysed material, the value of beta angle is selected so that the value of the scatter, defined by a root-mean-square value, is minimum. On the basis of such a calculation, an empirical expression for beta is proposed, that takes into account the values of bending and torsion fatigue strengths at a reference number of loading cycles. According to such an expression, beta is constant for a given material.
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Critical Plane Orientation Influence on Multiaxial High-Cycle Fatigue Assessment
Physical Mesomechanics, 2015Co-Authors: Andrea Carpinteri, Daniela Scorza, C. Ronchei, Sabrina VantadoriAbstract:In the present paper, the multiaxial fatigue lifetime of structural components failing in the high-cycle fatigue regime is evaluated by employing the modified Carpinteri-Spagnoli (C-S) multiaxial fatigue criterion based on the Critical Plane approach. In the above criterion, the Critical Plane position is linked to averaged principal stress directions through an off-angle 8. Then, the fatigue damage parameter used is determined by a nonlinear combination of an equivalent normal stress amplitude and the shear stress amplitude acting on the Critical Plane. In the present paper, some modifications of the original expression for the off-angle 8 are implemented in the modified Carpinteri-Spagnoli criterion. In particular, modified expressions recently proposed by Lagoda et al. are in accordance with the assumption originally developed by Carpinteri and co-workers, that is, the off-angle is a function of the ratio between the fatigue limit under fully reversed shear stress and that under fully reversed normal stress. Such expressions can be employed for metals ranging from mild to very hard fatigue behaviour. Some experimental data available in the literature are compared with the theoretical estimations and, only for materials with hard and very hard fatigue behaviour, the modified 8 relationships are shown to yield fatigue lifetime results slightly better than those determined through the original 8 expression.
Andrea Spagnoli - One of the best experts on this subject based on the ideXlab platform.
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Multiaxial Fatigue Damage Assessment of Welded Connections in Railway Steel Bridge using Critical Plane Approach
Procedia Engineering, 2018Co-Authors: Praveen K R, Andrea Spagnoli, S.s. Mishra, Prasad Babu, Andrea CarpinteriAbstract:Abstract As the number of heavy railway traffic load increased, concern over the accurate and actual fatigue damage of the bridge is intensified. Especially for bridges which were designed for light traffic load. The fatigue damage assessment of steel bridge connections is usually based on notion of uniaxial S-N curves given in the codes of practice. Until now, there is no consensus on a method which can precisely consider non-proportional multiaxial loading. The objective of this paper is to examine the applicability and appropriateness of the Critical Plane approach-based C-S criterion to perform the fatigue damage assessment in welded connections in railway steel bridge. A regular U trough railway steel bridge is analyzed using finite element software ANSYS 17.2 for standard railway traffic. The averaged principal stress directions determined through appropriate weight functions are used to orient the Critical Plane. Prediction of fatigue damage is performed through an equivalent stress represented by a quadratic combination of the normal and the shear stress components acting on the Critical Plane. Applicability of the C-S criterion is studied by assessing the fatigue damage of Critical welded connections and comparing with the λ - coefficient and cumulative damage method calculated according to Eurocode EN1993-1-9.
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Life estimation by varying the Critical Plane orientation in the modified Carpinteri-Spagnoli criterion
Fracture and Structural Integrity, 2015Co-Authors: Camilla Ronchei, Sabrina Vantadori, Andrea Carpinteri, Marta Kurek, Andrea Spagnoli, Giovanni Fortese, Tadeusz AgodaAbstract:The modified Carpinteri-Spagnoli (C-S) criterion is a multiaxial high-cycle fatigue criterion based on the Critical Plane approach. According to such a criterion, the orientation of the Critical Plane is linked to both the averaged directions of the principal stress axes and the fatigue properties of the material. The latter dependence is taken into account through a rotational angle, ?. Then, the multiaxial fatigue strength estimation is performed by computing an equivalent stress amplitude on the Critical Plane. In the present paper, some modifications of the original ? expression are implemented in the modified C-S criterion. More precisely, such modified expressions of ? depend on the ratio between the fatigue limit under fully reversed shear stress and that under fully reversed normal stress (in accordance with the original expression), and can be employed for metals ranging from mild to very hard fatigue behaviour. Some experimental data available in the literature are compared with the theoretical results in order to verify if the modified ?expressions are able to improve the fatigue strength estimation capability of the modified C-S criterion.
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Critical Plane criterion for fatigue life calculation time and frequency domain formulations
Procedia Engineering, 2015Co-Authors: Andrea Carpinteri, Daniela Scorza, Andrea Spagnoli, Camilla Ronchei, Sabrina VantadoriAbstract:Abstract A frequency-domain Critical Plane criterion is here employed to estimate fatigue life of smooth metallic structural components under multiaxial random loading. The procedure set out in the present paper consists of the following three steps: (i) definition of the Critical Plane; (ii) PSD evaluation of an equivalent normal stress; (iii) determination of fatigue life. The criterion is theoretically developed and numerically validated by employing experimental fatigue results for structural steel subjected to combined bending and torsion.
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reformulation in the frequency domain of a Critical Plane based multiaxial fatigue criterion
International Journal of Fatigue, 2014Co-Authors: Andrea Carpinteri, Andrea Spagnoli, Sabrina VantadoriAbstract:Abstract In the present paper, a new computationally-efficient frequency domain formulation of the Critical Plane-based Carpinteri–Spagnoli (C–S) criterion is proposed to evaluate the fatigue lives of smooth metallic structures subjected to multiaxial random loading. The Critical Plane orientation is here proposed to depend on the Power Spectral Density (PSD) matrix of the stress tensor. Then, the PSD function of an equivalent normal stress is defined by considering a linear combination of the PSD functions of the normal stress and the projected shear stress along the direction of maximum variance, with such stresses acting on the Critical Plane. Such an equivalent PSD function allows us to apply the Tovo–Benasciutti method to estimate the fatigue life of the structural components. The present frequency domain formulation of the C–S criterion is applied to some relevant fatigue tests related to smooth specimens under non-proportional bending and torsion random loading.
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A Strain-based Multiaxial Fatigue Criterion Connected to the Critical Plane Approach
Procedia Engineering, 2014Co-Authors: Andrea Carpinteri, Andrea Spagnoli, Camilla Ronchei, Sabrina VantadoriAbstract:Abstract A Critical Plane-based high-cycle multiaxial fatigue criterion, known as the Carpinteri-Spagnoli (C-S) criterion, is here extended to evaluate the fatigue lifetime of plain metallic components under constant amplitude loading in the low/medium-cycle regime. An equivalent strain amplitude, computed through a quadratic combinations of strain components in the Critical Plane, is taken as the fatigue damage parameter. A validation by experimental data pertaining the biaxial fatigue of plain steel specimens under both proportional and non-proportional loadings is performed.
Tadeusz łagoda - One of the best experts on this subject based on the ideXlab platform.
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estimation of fatigue life under multiaxial loading by varying the Critical Plane orientation
International Journal of Fatigue, 2017Co-Authors: Andrea Carpinteri, Marta Kurek, Tadeusz łagoda, Sabrina VantadoriAbstract:Abstract Fatigue life of different metallic materials under multiaxial loading is evaluated by employing the Critical Plane-based criterion proposed by some of the present authors. According to such a criterion, the multiaxial fatigue strength is assessed through an equivalent stress expressed by a linear combination of the normal stress amplitude and the shear stress amplitude acting on the Critical Plane. The Critical Plane orientation is determined by a novel expression, which is a non-linear function of the ratio between the fully reversed stress fatigue limits (τaf,−1/σaf,−1), and such an expression can be employed for any value of this ratio. Some experimental fatigue life data related to smooth specimens under combined normal loading (tension or bending) and torsion loading are compared with the theoretical estimations deduced through the above criterion.
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a correction in the algorithm of fatigue life calculation based on the Critical Plane approach
International Journal of Fatigue, 2016Co-Authors: Aleksander Karolczuk, Krzysztof Kluger, Tadeusz łagodaAbstract:Abstract The paper presents the algorithm for calculating the fatigue life taking into account the variability of coefficients occurring in the multiaxial fatigue criterion depending on the number of cycles to failure. The algorithm has been analysed under uniaxial cyclic loads and a combination of bending and torsion for four structural materials. Significant increase of convergence of calculated and experimental fatigue life using the new algorithm as compared to the classical approach for five selected multiaxial fatigue criteria based on a Critical Plane has been demonstrated.
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lifetime of semi ductile materials through the Critical Plane approach
International Journal of Fatigue, 2014Co-Authors: Karolina Walat, Tadeusz łagodaAbstract:Abstract This paper presents the results of fatigue strength estimation depending on the variable orientation of the Critical Plane for proportional and non-proportional bending and torsion with regard to specimens made of aluminium alloy 2017A. The algorithm applied for the fatigue strength evaluation is based on the Carpinteri–Spagnoli proposal and its subsequent modifications in accordance with the ideas developed by the authors. The objective of this paper is to search for a model which offers the best possible results of fatigue strength estimation for materials with properties which are intermediate between elastic-brittle and elastic–plastic, such as aluminium alloys, and a further insight into them with regard to their fatigue strength.
Ewald Macha - One of the best experts on this subject based on the ideXlab platform.
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verification of fatigue Critical Plane position according to variance and damage accumulation methods under multiaxial loading
International Journal of Fatigue, 2014Co-Authors: Zbigniew Marciniak, Dariusz Rozumek, Ewald MachaAbstract:Abstract The paper presents a comparison of fracture Plane position gained from experimental tests of specimens under multiaxial loading and theoretical ones from calculation according to variance and damage accumulation methods. In the variance method it is assumed that the Plane in which the maximum variance of the equivalent stress appears is Critical for a material and the fatigue fracture should be expected in this Plane. In the damage accumulation method the fatigue Critical Plane is assumed to be the Plane which suffered the greatest damage during service loading. For both methods the equivalent stress is calculated according to the multiaxial fatigue failure criteria of (i) maximum normal stresses, (ii) maximum shear stresses as well as (iii) maximum normal and shear stresses in the Critical Plane.
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Fatigue Fracture Planes and the Critical Plane Orientations in Multiaxial Fatigue Failure Criteria
2013Co-Authors: Aleksander Karolczuk, Ewald MachaAbstract:This paper deals with the problem of the Critical Plane determination formultiaxial fatigue failure criteria. Experimental results from multiaxial proportional,non-proportional cyclic loading and variable-amplitude bending and torsion were usedto determine the macroscopic fracture Plane orientations and the fatigue lives. Someknown multiaxial Critical Plane criteria were verified based on the fracture Planeorientations and experimental fatigue lives. It was concluded that frequently the Criticaland fracture Plane orientations do not coincide. However, the morphology of fracturePlanes is a key for an appropriate choice of the fatigue failure criterion for the fatiguelife estimation.
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Estimation of the fatigue life of high strength steel under variable-amplitude tension with torsion: Use of the energy parameter in the Critical Plane
European Structural Integrity Society, 2007Co-Authors: Tadeusz Łagoda, Ewald Macha, Adam Niesłony, Franck MorelAbstract:Abstract The paper concerns application of the energy parameter, being a sum of the elastic and plastic strain energy density in the Critical Plane, for describing experimental data obtained in fatigue tests of 35NCD16 steel, subjected to constant amplitude tension-compression, torsion and variable amplitude tension-compression, torsion and combined proportional tension with torsion. It has been shown that the normal strain energy density in the Critical Plane is a suitable parameter for correlation of fatigue lives of 35NCD16 steel under considered kinds of loading. The Critical Plane is the Plane where the normal strain energy density reaches its maximum value.
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A Review of Critical Plane Orientations in Multiaxial Fatigue Failure Criteria of Metallic Materials
International Journal of Fracture, 2005Co-Authors: Aleksander Karolczuk, Ewald MachaAbstract:The paper presents a review of multiaxial fatigue failure criteria based on the Critical Plane concept. The criteria have been divided into three groups, according to the fatigue damage parameter used in the criterion, i.e. (i) stress, (ii) strain and (iii) strain energy density criteria. Each criterion was described mainly by the Critical Plane orientation. Multiaxial fatigue criteria based on the Critical Plane concept usually apply different loading parameters in the Critical Plane whose orientation is determined by (a) only shear loading parameters (crack Mode II or III), (b) only normal loading parameters (crack Mode I) or sometimes (c) mixed loading parameters (mixed crack Mode). There are also criteria based on few Critical Plane orientations and criteria based on Critical Plane orientations determined by a weighted averaging process of rotating principal stress axes.
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A review of Critical Plane orientations in multiaxial fatigue failure criteria of metallic materials
International Journal of Fracture, 2005Co-Authors: Aleksander Karolczuk, Ewald MachaAbstract:The paper presents a review of multiaxial fatigue failure criteria based on the Critical Plane concept. The criteria have been divided into three groups, according to the fatigue damage parameter used in the criterion, i.e. (i) stress, (ii) strain and (iii) strain energy density criteria. Each criterion was described mainly by the Critical Plane orientation. Multiaxial fatigue criteria based on the crit-ical Plane concept usually apply different loading parameters in the Critical Plane whose orientation is determined by (a) only shear loading parameters (crack Mode II or III), (b) only normal loading parameters (crack Mode I) or sometimes (c) mixed loading parameters (mixed crack Mode). There are also criteria based on few Critical Plane orientations and criteria based on Critical Plane orienta-tions determined by a weighted averaging process of rotating principal stress axes. Nomenclature Loading parameters J Jintegral R stress ratio R = σ min /σ max T a generalised shear stress amplitude W strain energy density W II,A , W II,B strain energy density for Mode II of cases A and B cracks, respectively χ angle determining the shear direction in the Critical Plane described by ζ , ξ angles ε normal strain γ shear strain ρ * stabilised stress tensor σ ,τ normal stress and shear stress, respectively ζ , ξ angles in spherical coordinate system describing the normal direction to the Critical Plane in relation to the basic Cartesian coordinate system Oxyz Material coefficients b, c fatigue strength exponent and fatigue ductility exponent, respec-tively E, G Young's modulus and Kirchhoff's modulus, respectively 268 Aleksander Karolczuk and Ewald Macha n , K exponent and coefficient of cyclic hardening, respectively γ f shear fatigue ductility coefficient ε f fatigue ductility coefficient ν Poisson's ratio σ f fatigue strength coefficient σ y , σ u yield stress and ultimate strength, respectively τ f shear fatigue strength coefficient General N f number of cycles to failure t time Subscripts and others a amplitude b bending af fatigue limit c Critical value e, p elastic, plastic eff, eq effective and equivalent, respectively h hydrostatic ij (i, j = x, y, z) components in the Cartesian coordinate system Oxyz m, max, min mean, maximum and minimum value in time domain, respec-tively n in the Plane with normal vector n ns along direction s on the Plane with normal vector n oct octahedral s along direction s µ microscopic I, II, III, ou crack Mode I, Mode II, Mode III and mixed Mode, respec-tively range
