2024-03-29T05:15:36Z
https://www.fracturae.com/index.php/index/oai
oai:ojs.www.fracturae.com:article/2147
2019-08-28T06:53:26Z
fis:IGF2018
Numerical modelling of residual stress redistribution induced by TIG-dressing: TIG-dressing numerical modelling
Ferro, Paolo
Berto, Filippo
Bonollo, Franco
Montanari, Roberto
Numerical modelling
Welding
TIG-dressing
Residual stress
Microstructure
Phase transformation
TIG-dressing is a technique used to improve the fatigue strength of welded joints by a remelting of the weld toe region that promotes both a smoother transition between the plate and the weld crown and a residual stress redistribution. These effects are very hard to be quantified by numerical simulation since a highly coupled thermo-fluid-mechanical analysis is required. However, if the final weld toe geometry is supposed to be known or a-posteriori measured, a simplified numerical method can be used to simulate the residual tress redistribution that uses the activation-deactivation function of elements. This technique is applied to a real steel weldment and results, in terms of phases proportions and residual stress redistribution, were found in good agreement both with data coming from metallurgical analysis and the improved fatigue strength observed on welded joints after the TIG-dressing operation.
Gruppo Italiano Frattura (IGF)
2018-12-03
info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
application/pdf
https://www.fracturae.com/index.php/fis/article/view/2147
Frattura ed Integrità Strutturale; Vol. 13 No. 47 (2019): January 2019; 221-230
Frattura ed Integrità Strutturale; V. 13 N. 47 (2019): January 2019; 221-230
1971-8993
eng
https://www.fracturae.com/index.php/fis/article/view/2147/2294
https://www.fracturae.com/index.php/fis/article/view/2147/2295
Copyright (c) 2019 Paolo Ferro, Filippo Berto, Franco Bonollo, Roberto Montanari
oai:ojs.www.fracturae.com:article/2165
2019-08-28T06:57:14Z
fis:IGF2018
Ductile damage evolution law for proportional and non-proportional loading conditions
Fincato, Riccardo
Tsutsumi, Seiichiro
Momii, Hideto
Ductile damage
Elastoplasticity
Non-proportional loading
Damage Subloading Surface model
The characterization of ductile damage evolution, and its description, have been the object of extensive research in the continuum damage mechanic field. Many different models have been developed since the pioneering works carried out a few decades ago. In detail, the stress triaxiality and the Lode angle parameters have been identified as the two main variables that affect the material ductility. The literature offers a great number of investigations under monotonic loading conditions, however, a proper characterization of the damage evolution under cyclic loading or non-proportional loading is still missing.
In this paper, an unconventional coupled elastoplastic and damage constitutive model with a Mohr-Coulomb failure criterion is presented. The novelty of this study is represented by the modification of the ductile damage law in order to consider the damage evolution under non-proportional loading conditions. Therefore, the idea is to investigate the structural response of a steel bridge column subjected to a cyclic non-proportional loading, showing how, a different approach in the description of the ductile damage evolution, is necessary for a realistic description of the pier behavior.
Gruppo Italiano Frattura (IGF)
2018-12-03
info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
application/pdf
https://www.fracturae.com/index.php/fis/article/view/2165
Frattura ed Integrità Strutturale; Vol. 13 No. 47 (2019): January 2019; 231-246
Frattura ed Integrità Strutturale; V. 13 N. 47 (2019): January 2019; 231-246
1971-8993
eng
https://www.fracturae.com/index.php/fis/article/view/2165/2299
https://www.fracturae.com/index.php/fis/article/view/2165/2297
Copyright (c) 2019 Riccardo Fincato, Seiichiro Tsutsumi, Hideto Momii
oai:ojs.www.fracturae.com:article/2173
2019-08-28T06:56:40Z
fis:IGF2018
Analytical and numerical study of the stress field in a circular semi- ring under combined diametral compression and bending
Kourkoulis, Stavros K
Pasiou, Ermioni D.
Markides, Christos F.
Circular semi-ring
Brazilian-disc test
Tensile strength
Complex potentials
Finite element method
Stress field
The stress field developed in a circular semi-ring under the combined action of diametral compression and bending is explored both analytically and numerically. The analytic solution is implemented by means of the complex potentials technique as it was formulated by Muskhelishvili, while for the numerical study a finite element model, properly validated based on experimental data, is used. The analytic solution provided closed formulae for the stress field along strategic loci of the specimen, while the numerical model permitted thorough parametric investigation of the dependence of critical quantities on geometrical and loading factors. The idea behind the study is to assess the potentialities of the circular semi-ring as a possible substitute of the familiar Brazilian disc, in the direction of curing drawbacks of the latter. It was concluded that a circular semi-ring subjected to eccentric diametral compression provides reliable data for the tensile strength of very brittle materials, relieved from ambiguities characterizing the standardized Brazilian-disc test.
Gruppo Italiano Frattura (IGF)
2018-12-03
info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
application/pdf
https://www.fracturae.com/index.php/fis/article/view/2173
Frattura ed Integrità Strutturale; Vol. 13 No. 47 (2019): January 2019; 247-265
Frattura ed Integrità Strutturale; V. 13 N. 47 (2019): January 2019; 247-265
1971-8993
eng
https://www.fracturae.com/index.php/fis/article/view/2173/2300
https://www.fracturae.com/index.php/fis/article/view/2173/2301
Copyright (c) 2019 Stavros K Kourkoulis, Ermioni D. Pasiou, Christos F. Markides
oai:ojs.www.fracturae.com:article/2178
2019-08-28T06:58:08Z
fis:IGF2018
Mechanical and fracture properties of particleboard
Marsavina, Liviu
POP, Ion Octavian
LINUL, Emanoil
Particleboard
Fracture Toughness
Digital Image Correlation
Fracture toughness of wooden composites
Particleboard (PB) are wood-based composites with fine wood fibers bound together by a small amount of polymeric adhesive, widely used in furniture industry and civil engineering. PB plates can be painted, laminated or veneered, and have good dimensional stability and load bearing capacity when properly designed. However, the deformation and fracture of such elements create malfunctions of structures mad of MDF. This paper presents experimental results obtained for three point bending (TPB) tests, mode I and mode II fracture toughness. The bending tests were carried on rectangular specimens, while the fracture toughness tests were performed on Single Edge Notched Bend (SENB) specimen for mode I, respectively on Compact Shear (CS) specimens for mode II loading. Digital Image Correlation techique allow the determination of Crack Relative Displacement Factor and estimation of Energy Release Rate.
Gruppo Italiano Frattura (IGF)
2018-12-03
info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
application/pdf
https://www.fracturae.com/index.php/fis/article/view/2178
Frattura ed Integrità Strutturale; Vol. 13 No. 47 (2019): January 2019; 266-276
Frattura ed Integrità Strutturale; V. 13 N. 47 (2019): January 2019; 266-276
1971-8993
eng
https://www.fracturae.com/index.php/fis/article/view/2178/2341
https://www.fracturae.com/index.php/fis/article/view/2178/2303
Copyright (c) 2019 Liviu Marsavina, Ion Octavian POP, Emanoil LINUL
oai:ojs.www.fracturae.com:article/2180
2019-08-28T06:59:02Z
fis:IGF2018
A numerical model based on ALE formulation to predict crack propagation in sandwich structures
Funari, Marco Francesco
Greco, Fabrizio
Lonetti, Paolo
Spadea, Saverio
Moving Mesh Method;
Crack Propagation
Sandwich Structures
ALE
Finite Element Method
Debonding Mechanisms
A numerical model to predict crack propagation phenomena in sandwich structures is proposed. The model incorporates shear deformable beams to simulate high performance external skins and a 2D elastic domain to model the internal core. Crack propagation is predicted in both core and external skin-to-core interfaces by means of a numerical strategy based on an Arbitrary Lagrangian–Eulerian (ALE) formulation. Debonding phenomena are simulated by weak based connections, in which moving interfacial elements with damage constitutive laws are able to reproduce the crack evolution. Crack growth in the core is analyzed through a moving mesh approach, where a proper fracture criterion and mesh refitting procedure are introduced to predict crack tip front direction and displacement. The moving mesh technique, combined with a multilayer formulation, ensures a significant reduction of the computational costs. The accuracy of the proposed approach is verified through comparisons with experimental and numerical results. Simulations in a dynamic framework are developed to identify the influence of inertial effects on debonding phenomena arising when different core typologies are employed. Crack propagation in the core of sandwich structures is also analyzed on the basis of fracture parameters experimentally determined on commercially available foams.
Gruppo Italiano Frattura (IGF)
2018-12-03
info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
application/pdf
https://www.fracturae.com/index.php/fis/article/view/2180
Frattura ed Integrità Strutturale; Vol. 13 No. 47 (2019): January 2019; 277-293
Frattura ed Integrità Strutturale; V. 13 N. 47 (2019): January 2019; 277-293
1971-8993
eng
https://www.fracturae.com/index.php/fis/article/view/2180/2304
https://www.fracturae.com/index.php/fis/article/view/2180/2305
Copyright (c) 2019 Marco F Funari, Fabrizio Greco, Paolo Lonetti, Saverio Spadea
oai:ojs.www.fracturae.com:article/2182
2019-08-28T06:59:46Z
fis:IGF2018
Comparison of tensile strength and fracture toughness under mode I and II loading of co-cured and co-bonded CFRP joints
Pirondi, Alessandro
Moroni, Fabrizio
Pernechele, Chiara
Gaita, Arturo
Vescovi, Luca
fracture toughness
Carbon-Fiber Reinforced Polymer
bonded joints
Adhesive bonding is the elective joining system between Carbon-Fiber Reinforced Polymer (CFRP) parts because, with respect to fastening, it allows a large connection area, no additional parts (hence weight saving) and no need to drill holes into the composite, that is always detrimental for the strength due to the possibility of developing damage. However, the choice of bonding CFRP should be evaluated as alternative to direct curing in terms of strength and durability, compared to cost and manufacturing time and complexity. In this work, a comparison between co-cured and co-bonded CFRP is done with respect to tensile strength and mode I and mode II fracture toughness, in order to understand whether co-bonding guarantees the same performance of a co-cured composite part.Adhesive bonding is the elective joining system between Carbon-Fiber Reinforced Polymer (CFRP) parts because, with respect to fastening, it allows a large connection area, no additional parts (hence weight saving) and no need to drill holes into the composite, that is always detrimental for the strength due to the possibility of developing damage. However, the choice of bonding CFRP should be evaluated as alternative to direct curing in terms of strength and durability, compared to cost and manufacturing time and complexity. In this work, a comparison between co-cured and co-bonded CFRP is done with respect to tensile strength and mode I and mode II fracture toughness, in order to understand whether co-bonding guarantees the same performance of a co-cured composite part.
Gruppo Italiano Frattura (IGF)
2018-12-12
info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
application/pdf
https://www.fracturae.com/index.php/fis/article/view/2182
Frattura ed Integrità Strutturale; Vol. 13 No. 47 (2019): January 2019; 294-302
Frattura ed Integrità Strutturale; V. 13 N. 47 (2019): January 2019; 294-302
1971-8993
eng
https://www.fracturae.com/index.php/fis/article/view/2182/2308
https://www.fracturae.com/index.php/fis/article/view/2182/2307
Copyright (c) 2019 Alessandro Pirondi, Fabrizio Moroni, Chiara Pernechele, Arturo Gaita, Luca Vescovi
oai:ojs.www.fracturae.com:article/2189
2019-08-28T07:00:27Z
fis:IGF2018
The effect of low-cycle fatigue on evolution of fracture mechanics parameters in residual stress field caused by cold hole expansion
Matvienko, Yury
Pisarev, Vladimir
Eleonsky, Svyatoslav
Cold expansion
Crack growth
Crack mouth opening displacement
Stress intensity factor
T-stress
Localized displacement measurements based on electronic speckle-pattern interferometry are used to obtain crack mouth opening displacement (CMOD), stress intensity factor (SIF) and T-stress values during crack growth around cold-expanded holes. The specimens with a central open hole are made from 2024 aluminium alloy. The expansion level is 5% of nominal interference. The results are obtained for the same stress range = 350 MPa, but different stress ratio R = –0.4 and R = –1.0. A sequence of narrow notches, inserted under the constant external load, serves for crack modelling at different stages of cyclic loading. Initial experimental data represent in-plane displacement component values measured in the vicinity of the crack tip. The transition from in-plane displacement components to SIF and T-stress values follows from the relationships of modified version of the crack compliance method. The crack length curves of CMOD, SIF and T-stress profiles are obtained for different stages of cyclic loading. These data provide the construction of dependencies of fracture mechanics parameters for cracks of fixed lengths from the loading cycle number.
Gruppo Italiano Frattura (IGF)
2018-12-05
info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
application/pdf
https://www.fracturae.com/index.php/fis/article/view/2189
Frattura ed Integrità Strutturale; Vol. 13 No. 47 (2019): January 2019; 303-320
Frattura ed Integrità Strutturale; V. 13 N. 47 (2019): January 2019; 303-320
1971-8993
eng
https://www.fracturae.com/index.php/fis/article/view/2189/2309
https://www.fracturae.com/index.php/fis/article/view/2189/2310
Copyright (c) 2019 Yury Matvienko, Vladimir Pisarev, Svyatoslav Eleonsky
oai:ojs.www.fracturae.com:article/2232
2019-08-28T07:01:07Z
fis:IGF2018
Numerical simulation of the de-bonding phenomenon of FRCM strengthening systems
Grande, Ernesto
Imbimbo, Maura
Marfia, Sonia
Sacco, Elio
FRCM
De-bonding
Analytical model
Interface
Aim of the paper is to present a one dimensional simple model for the study of the bond behavior of Fabric Reinforced Cementitious Matrix (FRCM) strengthening systems externally applied to structural substrates. The equilibrium of an infinitesimal portion of the reinforcement and the mortar layers composing the strengthening systems allows to derive the governing equations. An analytical solution is determined solving the system of differential equations. In particular, in the first part of the paper a nonlinear shear-stress slip law characterized by a brittle post-peak behavior with a residual shear strength in the post peak phase is introduced for either the lower reinforcement-mortar interface (approach 1) or both the lower and the upper interface (approach 2). In the latter approach, a calibration of the shear strength of the upper interface is proposed in order to implicitly account for the effect of the damage of the mortar on the bond behavior. In the second part of the paper it is presented the solution of the problem in the case of softening behavior by approximating the shear-stress slip law throughout a step function. Comparisons with experimental data, available in literature, are presented in order to assess the reliability of the proposed approach.
Gruppo Italiano Frattura (IGF)
2018-12-04
info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
application/pdf
https://www.fracturae.com/index.php/fis/article/view/2232
Frattura ed Integrità Strutturale; Vol. 13 No. 47 (2019): January 2019; 321-333
Frattura ed Integrità Strutturale; V. 13 N. 47 (2019): January 2019; 321-333
1971-8993
eng
https://www.fracturae.com/index.php/fis/article/view/2232/2311
https://www.fracturae.com/index.php/fis/article/view/2232/2312
Copyright (c) 2019 Ernesto Grande, Maura Imbimbo, Sonia Marfia, Elio Sacco
oai:ojs.www.fracturae.com:article/2320
2019-08-28T07:01:55Z
fis:IGF2018
Analysis of dissipated energy and temperature fields at severe notches of AISI 304L stainless steel specimens
Rigon, Daniele
Ricotta, Mauro
Meneghetti, Giovanni
Energy Distribution
Fatigue
Notch Effect
In the last years, a large amount of fatigue test results from plain and bluntly notched specimens made of AISI 304L stainless steel were synthetized in a single scatter band by adopting the specific heat loss per cycle (Q) as a damage parameter. During a fatigue test, the Q parameter can be evaluated measuring the cooling gradient at a point of the specimens after having suddenly stopped the fatigue test. This measurement can be done by using thermocouples; however, due to the high stress concentration at the tip of severely notched components analysed in the present paper, an infrared camera achieving a much improved spatial resolution was adopted. A data processing technique is presented to investigate the heat energy distribution close to the notch tip of hot-rolled AISI 304L stainless steel specimens, having notch tip radii equal to 3, 1 and 0.5 mm and subjected to constant amplitude cyclic loads. A thermal finite element analysis was also performed by assigning heat generation in the appropriate region close to the notch tip. Then the numerical temperature values were compared with the experimental measurement.
Gruppo Italiano Frattura (IGF)
2018-12-06
info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
application/pdf
https://www.fracturae.com/index.php/fis/article/view/2320
Frattura ed Integrità Strutturale; Vol. 13 No. 47 (2019): January 2019; 334-347
Frattura ed Integrità Strutturale; V. 13 N. 47 (2019): January 2019; 334-347
1971-8993
eng
https://www.fracturae.com/index.php/fis/article/view/2320/2331
https://www.fracturae.com/index.php/fis/article/view/2320/2332
Copyright (c) 2019 Daniele Rigon, Mauro Ricotta, Giovanni Meneghetti