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Modern defect assessment procedures assume flaws that cannot be considered as a reduction in section are a sharp crack, a conservative assumption that can result in pessimistic evaluations. These may result in a defect prematurely failing a structural integrity assessment due to worst case assumptions about material properties, structure geometry and defect size. This study has developed an engineering assessment approach to estimate the resistance to fracture of structures containing non-sharp defects. The new procedure builds on a two-parameter constraint-based approach used to assess low constraint sharp defects. The new methodology has been developed and validated using testing and finite element analysis. An S355J2+N structural steel was used for the experimental work composing of a large test programme of Single Edge Notch Bend (SEN(B)) specimens with deep sharp cracks and U-shaped notches. These were used to measure the increase in effective fracture toughness that accompanies increasing notch tip radius. Additional tests of SEN(B) specimens with shallow sharp cracks were used to quantify the standard constraint behaviour of the material. In comparison to the methodology used to allow for constraint in fracture assessments in BS 7910/R6, a notch corrected constraint method based on a J-Q approach is proposed. A notch constraint relationship is defined between the level of notch constraint loss due to increasing crack tip acuity and resulting increase in fracture toughness. The approach is validated using notched C(T) experimental data from open literature for the same material. A two-parameter Weibull model is used to describe the crack and notch toughness probability of failure to incorporate different confidence levels into the analysis. The methodology shows to be a promising method for assessment of non-sharp defects where benefit may be taken from resolving crack tip acuity.

In today's industry, complex parts made of steel are a reality thanks to the introduction of additive manufacturing, which offers technological improvements in conventional and large manufacturing industries that rely on molds and dies for mass production. However, the rapid solidification, remelting and reheating during the process and the uneven properties of the parts might present some difficulties in expanding its application in some sectors. For example, H13 tool steel offers exceptional properties, but finding the correct post-heating treatment for additively manufactured parts with reliable and repeatable properties is still a challenge., This work was supported by the São Paulo Research Foundation (FAPESP) grants #2018/06045-0 and #2019/06276-4, Brazilian National Council for Scientific and Technological Development (CNPq) grant #305446/2020-7, and the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior – Brasil (CAPES). The authors thank the Brazilian Nanotechnology National Laboratory (LNNano) for technical support during TEM work (proposals SEM-C1-26018, TEM-C1-27145, and TEM-FT-20232430). Fabiano Emmanuel Montoro, Dr. Gisele Maria Leite Dalmonico, and Dr. Vishnu Mogili are acknowledged for the operation of FIB-SEM and TEM. The Laboratory of Structure Characterization at the Federal University of São Carlos (LCE/UFSCar) is acknowledged for support during EBSD analyses. We acknowledge DESY (Hamburg, Germany), a member of the Helmholtz Association HGF, for the provision of experimental facilities. Parts of this research were carried out at PETRA III (proposal I-20230101 EC) and we would like to thank Dr. Guilherme Abreu Faria and Dr. Marc-André Nielsen for assistance in using beamline P61A. The authors thank Prof. Helio Goldenstein and Dr. Giovani G. Ribamar for the dilatometry experiments. Julian Avila is a Serra Hunter fellow and a CNPq fellow., Postprint (published version)

Most serious weldment failures have catastrophic consequences in terms of damage to other equipment, loss of production, and risks to worker health and safety. For the above reasons, there is a tendency to find the line between safety and disaster, and this requires a guarantee of the integrity of the welded structure even if a crack is present. The structural and mechanical heterogeneity of a welded joint affects its resistance to cracking in both the elastic and plastic regions. Therefore, it is important to define the test method and the position of the fatigue crack. The behavior of an elasto-plastic material, during stable crack growth can be described by the J-  a diagram. As the crack propagates, a point on the curve is defined, which represents the critical value of the Jintegral. The aim of this experiment is to determine JIC value and the procedure is reflected in the determination of the R curve, i.e. the J‒a curve, which consists of the value of the J integral for uniform crack increments a. In this paper, two SEN(B) specimens with the fatigue crack in the parent material (PM) and weld metal (WM) were tested according to standard ASTM E1820 at room temperature (RT) as well as three specimens with the fatigue crack in the weld metal (WM) at RT, -20 0C, -30 0C.

In this work, the essential work of fracture (EWF) method is introduced for a peridynamic (PD) material model to characterize fracture toughness of ductile materials. First, an analytical derivation for the path-independence of the PD J-integral is provided. Thereafter, the classical J-integral and PD J-integral are computed on a number of analytical crack problems, for subsequent investigation on how it performs under large scale yielding of thin sheets. To represent a highly nonlinear elastic behavior, a new adaptive bond stiffness calibration and a modified bond-damage model with gradual softening are proposed. The model is employed for two different materials: a lower-ductility bainitic-martensitic steel and a higher-ductility bainitic steel. Up to the start of the softening phase, the PD model recovers the experimentally obtained stress-strain response of both materials. Due to the high failure sensitivity on the presence of defects for the lower-ductility material, the PD model could not recover the experimentally obtained EWF values. For the higher-ductility bainitic material, the PD model was able to match very well the experimentally obtained EWF values. Moreover, the J-integral value obtained from the PD model, at the absolute maximum specimen load, matched the corresponding EWF value., Validerad;2023;Nivå 2;2023-08-18 (marisr);License fulltext: CC-BY

In this work, the essential work of fracture (EWF) method is introduced for a peridynamic (PD) material model to characterize fracture toughness of ductile materials. First, an analytical derivation for the path-independence of the PD J-integral is provided. Thereafter, the classical J-integral and PD J-integral are computed on a number of analytical crack problems, for subsequent investigation on how it performs under large scale yielding of thin sheets. To represent a highly nonlinear elastic behavior, a new adaptive bond stiffness calibration and a modified bond-damage model with gradual softening are proposed. The model is employed for two different materials: a lower-ductility bainitic-martensitic steel and a higher-ductility bainitic steel. Up to the start of the softening phase, the PD model recovers the experimentally obtained stress-strain response of both materials. Due to the high failure sensitivity on the presence of defects for the lower-ductility material, the PD model could not recover the experimentally obtained EWF values. For the higher-ductility bainitic material, the PD model was able to match very well the experimentally obtained EWF values. Moreover, the J-integral value obtained from the PD model, at the absolute maximum specimen load, matched the corresponding EWF value., Validerad;2023;Nivå 2;2023-08-18 (marisr);License fulltext: CC-BY

To evaluate the behavior of a homogeneous material in the presence of a crack-type defect, the value of the critical stress-intensity factor, KIc, was determined as a measure of the fracture toughness of the tested steel under the conditions of a plane stress state, at two test temperatures, 20 C and 540 C. The experiments were carried out using the method of testing one specimen with successive partial unloading, which aims to r occurs during the test. In addition to the experimental analysis, a numerical simulation of the behavior of the specimens under static and dynamic loading was performed. The numerical analysis is based on the experimentally obtained yield strength and tensile strength values of the investigated steel, and was done in Ansys Workbench R21 software package, which relies on finite element method, FEM. The results obtained by numerical analysis showed good agreement with the experimentally obtained results of the J-integral for specimens tested at room and elevated temperature. Good agreement with the experimental results was shown, confirming the use of FEM for the load cases considered.

Fracture mechanics, as a scientific discipline dealing with the study of cracks in welded structures, has defined parameters and introduced new test methods in order to better determine the tendency to crack growth, critical conditions for rapid fracture development, material resistance to rapid crack propagation and better definition of other parameters for assessing the behaviour of the material and the safety of the structure in the presence of cracks. In this paper, the focus is on determination of the parameter of elastic-plastic mechanics of J-integral, more precisely, on examination of the critical value of J-integral (JIc) of the welded joint of HSLA steel. The position of the tip of the fatigue crack and the properties of the region where fracture propagation occurs are main indicators of influence of the heterogeneity of the NN-70 welded structure and mechanical properties. Resistance to cracking in the welded joint shows that the heterogeneity has a major impact on the resistance to crack initiation and propagation, in elastic as well as in the plastic region.

In this paper is presented the 1-point method for material behaviour prediction, in terms of fracture toughness, of the ferritic steel EN 1.6310 in the transition temperature regime (-60°C and -90°C). Experiments were carried out at two different temperatures, representing two studies joined in one. Experimental testing was perfomed according to ASTM 1820 standard. This 1-point method is based on statistical processing (of 2-parameters Weibull statistics) of obtained experimental results, i.e. scattered J-integral values, of C(T) specimens with different geometries. Fixing value of one Weibull parameter and taking into account size-dependence of second one, fracture probabilities in the function of J-integral for large C(T)100 and C(T)200 were determined based on testing of C(T)50 specimen size. This research pointed out the sensitivty of proposed method on statistical sample size. One of the aims of proposed method was reducing the cost and price of laboratory tests in overall by predicting material behaviour and testing smaller C(T) specimen size. This research represents an upgrade of the Landes and Heerens works, and it is dedicated to their efforts in understanding and characterisation of transition temperature regime of ferritic steels.

Fracture mechanics, as a scientific discipline dealing with the study of cracks in welded structures, has defined parameters and introduced new test methods in order to better determine the tendency to crack growth, critical conditions for rapid fracture development, material resistance to rapid crack propagation and better definition of other parameters for assessing the behaviour of the material and the safety of the structure in the presence of cracks. In this paper, the focus is on determination of the parameter of elastic-plastic mechanics of J-integral, more precisely, on examination of the critical value of J-integral (JIc) of the welded joint of HSLA steel. The position of the tip of the fatigue crack and the properties of the region where fracture propagation occurs are main indicators of influence of the heterogeneity of the NN-70 welded structure and mechanical properties. Resistance to cracking in the welded joint shows that the heterogeneity has a major impact on the resistance to crack initiation and propagation, in elastic as well as in the plastic region.

Fracture mechanics, as a scientific discipline dealing with the study of cracks in welded structures, has defined parameters and introduced new test methods in order to better determine the tendency to crack growth, critical conditions for rapid fracture development, material resistance to rapid crack propagation and better definition of other parameters for assessing the behaviour of the material and the safety of the structure in the presence of cracks. In this paper, the focus is on determination of the parameter of elastic-plastic mechanics of J-integral, more precisely, on examination of the critical value of J-integral (JIc) of the welded joint of HSLA steel. The position of the tip of the fatigue crack and the properties of the region where fracture propagation occurs are main indicators of influence of the heterogeneity of the NN-70 welded structure and mechanical properties. Resistance to cracking in the welded joint shows that the heterogeneity has a major impact on the resistance to crack initiation and propagation, in elastic as well as in the plastic region.

This paper aims to investigate the effects of offset distance of crack stop hole (CSH) on steel plate with respect to its loading point. Laboratory tests and finite element simulations were performed to estimate the effect of offset distance from the midpoint of the specimens. The experimental study was performed in segments of rectangular plate stresses with a cyclic flexural load which applied through a mid-plane of the top surface of the specimen. 5 Hz frequency and 2 kN constant amplitude fatigue test were performed in the low cycle fatigue (LCF) range up to 10,000 cycles. Also, crack stop holes of 16 mm diameter were placed at the different offset distance from midpoint up to 100 mm in the range of 20 mm, and their effectiveness in Yield strength was evaluated by using laboratory test and test results were validated using a cyclic J-integral option using the ABAQUS FEM technique. The results of laboratory test as well as numerical analysis were synonymous. The offset distance of the CSH indicated a significant variation in the yield strength which in the range of 26.5–56.8% compared to the CSH at midpoint. This investigation reported a significant yield strength variation in the range of 19.3–42.1% with respect to CSH placed at mid-point of the specimen.

Due to its superior strength at high temperatures P/T91 steel is often applied in the chemical, petrochemical and fossil-fired power generation industries. The high strength is achieved by a suitable martensitic microstructure after appropriate heat treatment procedure. Welding is the most important process of joining the components in such plants, and the heat-affected zone is often the weakest part of these structures. Having in mind that the welded joint is the weakest area, it is necessary to know its properties and assess the level of its degradation. It was found that the life-limiting factor in case of P/T91 steel welded structures are the cracks located in the heat affected zones, more precisely in its intercritical region. In present paper the results of the fracture toughness measurement carried out on simulated P91 steel ICHAZ specimens produced using a weld simulator has been presented. The tests were done on two types of simulated specimens, those subjected to the subsequent PWHT and with those left untreated (without PWHT), at room temperature and 600 degrees C. For the J-integral estimation pin-loaded SEN(T) specimens were tested in plane stress conditions using the unloading compliance method of deriving a single specimen resistance curve and the eta-method.

Fracture toughness is one of the most important properties of a material. Being able toaccurately estimate the energy that goes into forming new crack surfaces is essential for the development of new materials, quality assurance, structural monitoring and failure analysis. Fracture toughness parameters are routinely determined by mechanical testing and are often used in numerical tools. Furthermore, fracture toughness is a common property in material specification. Numerical simulation of fracture toughness can reduce the need of mechanical testing and is sometimes the only viable alternative when mechanical testing is not an option, for example in component optimisation and in the assessment of operational structural components. However, complex fracture is a challenge in material modelling, which comes from that a material body is assumed to remain continuous in classical continuum mechanics. Classical continuum mechanics is formulated assuming a continuous body and that spatial derivatives are defined. However, this is not the case at cracks and other dis­ continuities. Complementing continuum mechanics with supplementary procedures for modelling discontinues can also add further challenges. Besides, the assumption of locality, that each material point only interacts with is immediate neighbouring points, becomes invalid for nanoscale geometries. Thus, fracture cannot easily be modelled. An alternative is therefore of interest. Peridynamics is a nonlocal extension of continuum mechanics with the constitutive model formulated as an integro-differential equation. The advantages of using an integral expression are foremost that long-range forces can be handled and that the theory is valid even in the presence of discontinuities, such as cracks, allowing unguided modelling of fracture. Since damage is introduced to the constitutive model of peridynamics, there is no requirement of supplementary procedures that can add further complications. Due to its nonlocal formu

Fracture toughness is one of the most important properties of a material. Being able toaccurately estimate the energy that goes into forming new crack surfaces is essential for the development of new materials, quality assurance, structural monitoring and failure analysis. Fracture toughness parameters are routinely determined by mechanical testing and are often used in numerical tools. Furthermore, fracture toughness is a common property in material specification. Numerical simulation of fracture toughness can reduce the need of mechanical testing and is sometimes the only viable alternative when mechanical testing is not an option, for example in component optimisation and in the assessment of operational structural components. However, complex fracture is a challenge in material modelling, which comes from that a material body is assumed to remain continuous in classical continuum mechanics. Classical continuum mechanics is formulated assuming a continuous body and that spatial derivatives are defined. However, this is not the case at cracks and other dis­ continuities. Complementing continuum mechanics with supplementary procedures for modelling discontinues can also add further challenges. Besides, the assumption of locality, that each material point only interacts with is immediate neighbouring points, becomes invalid for nanoscale geometries. Thus, fracture cannot easily be modelled. An alternative is therefore of interest. Peridynamics is a nonlocal extension of continuum mechanics with the constitutive model formulated as an integro-differential equation. The advantages of using an integral expression are foremost that long-range forces can be handled and that the theory is valid even in the presence of discontinuities, such as cracks, allowing unguided modelling of fracture. Since damage is introduced to the constitutive model of peridynamics, there is no requirement of supplementary procedures that can add further complications. Due to its nonlocal formu

Due to its superior strength at high temperatures P/T91 steel is often applied in the chemical, petrochemical and fossil-fired power generation industries. The high strength is achieved by a suitable martensitic microstructure after appropriate heat treatment procedure. Welding is the most important process of joining the components in such plants, and the heat-affected zone is often the weakest part of these structures. Having in mind that the welded joint is the weakest area, it is necessary to know its properties and assess the level of its degradation. It was found that the life-limiting factor in case of P/T91 steel welded structures are the cracks located in the heat affected zones, more precisely in its intercritical region. In present paper the results of the fracture toughness measurement carried out on simulated P91 steel ICHAZ specimens produced using a weld simulator has been presented. The tests were done on two types of simulated specimens, those subjected to the subsequent PWHT and with those left untreated (without PWHT), at room temperature and 600 degrees C. For the J-integral estimation pin-loaded SEN(T) specimens were tested in plane stress conditions using the unloading compliance method of deriving a single specimen resistance curve and the eta-method.

Due to its superior strength at high temperatures P/T91 steel is often applied in the chemical, petrochemical and fossil-fired power generation industries. The high strength is achieved by a suitable martensitic microstructure after appropriate heat treatment procedure. Welding is the most important process of joining the components in such plants, and the heat-affected zone is often the weakest part of these structures. Having in mind that the welded joint is the weakest area, it is necessary to know its properties and assess the level of its degradation. It was found that the life-limiting factor in case of P/T91 steel welded structures are the cracks located in the heat affected zones, more precisely in its intercritical region. In present paper the results of the fracture toughness measurement carried out on simulated P91 steel ICHAZ specimens produced using a weld simulator has been presented. The tests were done on two types of simulated specimens, those subjected to the subsequent PWHT and with those left untreated (without PWHT), at room temperature and 600 degrees C. For the J-integral estimation pin-loaded SEN(T) specimens were tested in plane stress conditions using the unloading compliance method of deriving a single specimen resistance curve and the eta-method.

This work concerns detailed numerical modelling of injection fracturing in chalk formations under 2–3 km burial. The conditions and properties are chosen to resemble field conditions as typically found in oil fields subject to water injection in the Central Graben in the North Sea off-shore Denmark, Norway and the UK, but the studied phenomena are general to injection fracturing irrespective of geographical location and technological application. The complexity of reality is a challenging factor when mathematical models of hydraulic fractures in the subsurface are formulated. To this end the finite element method and a multi physics approach is instrumental, and data from fields developed and operated under conditions prudent for modelling are equally important. In the present study, a poroelastic finite element model is applied and used under plane strain conditions for a linear fracture mechanics investigation. This approach is suitable for analysing fracturing in arrays of parallel and horizontal wells as can be found in many oil fields undergoing water-flooding. Based on realistic field data, e.g. reservoir properties and rate and pressure scenarios representative for typical fields in the North Sea region, fracture initiation and fracture growth are analysed in details in a realistic field setting. Using a formulation of the J-integral, that includes Functionally Graded Material and poroelastic effects, it is demonstrated that formation fracture toughness determines fracture initiation and fracture height. The fracture propagation speed is controlled by continuity, e.g. the injection rate must balance the leak-off from the fracture wall. By combining the fields of geotechnical engineering, petroleum engineering and mechanical engineering with realistic data measurements, this study provides a novel realistic study of how the producer and injector pressure influence the fracturing process for induced hydraulic fractures in a line drive.

In this work two approaches to the description of short fatigue crack growth rate under large-scale yielding condition were comprehensively tested: (i) plastic component of the J-integral and (ii) Polak model of crack propagation. The ability to predict residual fatigue life of bodies with short initial cracks was studied for stainless steels Sanicro 25 and 304L. Despite their coarse microstructure and very different cyclic stress-strain response, the employed continuum mechanics models were found to give satisfactory results. Finite element modeling was used to determine the J-integrals and to simulate the evolution of crack front shapes, which corresponded to the real cracks observed on the fracture surfaces of the specimens. Residual fatigue lives estimated by these models were in good agreement with the number of cycles to failure of individual test specimens strained at various total strain amplitudes. Moreover, the crack growth rates of both investigated materials fell onto the same curve that was previously obtained for other steels with different properties. Such a "master curve" was achieved using the plastic part of J-integral and it has the potential of being an advantageous tool to model the fatigue crack propagation under large-scale yielding regime without a need of any additional experimental data.

J-integral is a fracture mechanic parameter that can be used to characterize elastic-plastic fracture mechanic (EPFM) behavior. The path independent characteristic in J-integral is proposed by Rice [1], and it is widely used in a lot of research. Another approach is the load-displacement approach, where the J-integral is calculated by the area under the load-displacement curve. However, the validity of the J-integral value by load-displacement approach is yet to be confirmed. This paper is aimed to investigate the effect of crack length ratio of CT specimen to J-integral value by two approaches: path-integral approach and load-displacement approach. Finite element analysis of compact tension (CT) model with crack length ratio a/W between 0.2 to 0.5 was carried out under displacement δ between 0.2 to 1.0 mm using ANSYS parametric design language (APDL). The J value by path integral approach, Jpath is compared to the value calculated from load-displacement approach, Jp-d. It was found that path independency occurs for J value evaluated from path integral approach. A correction factor needs to be introduced since the load-displacement approach cannot be used for shallow crack cases.

Welding is one of the most common process in industrial or production engineering practice for components joining. Its main advantages are high speed in manufacturing combined with low costs and, usually, a high degree of flexibility, integrity and reliability. Nevertheless, welding is a highly complex metallurgical process and, therefore, weldments are susceptible to cracking, flaws and residual stresses which may lead to structural failure and life time reduction. Welded structures have wide range of applications in many industries. Steel grade DIN 15NiMoCrB4-5, which is a low-carbon microalloyed steel alloyed with Nickel and Molybdenum, which is used in line pipes for transporting oil and natural gas has been investigated. Its yield stress is 668 MPa and the UTS are close to 820 MPa. Catastrophic structure failure made of this steel grade due to fatigue is reported to cause sudden damage and loss to human-lives, as well as property. Hence, from end application point of view, knowledge on fracture toughness is of immense importance. Several tests were conducted on the welded joints. Fracture mechanics toughness testes using three point bending specimens were done. Obtained results of the applied force and CMOD were processed in order to determine the value of KIC, CTOD or J-integral. The pre-crack was created using fatigue and the crack propagation was measured using the unloading compliance method. Calculation of critical values ��� are compared with the values obtained by using FEM. The FEM model was defined on the basis of experimental condition in program Ansys. The goal of this research was to determine effect of welded joint geometry (different zone sizes) and crack location on fatigue life. First welded joints were made using the MIG procedure and investigated in terms of mechanical and fatigue properties. The focus of this study was on experimental and numerical analysis, with special focus on the heat-affected zone., Zavarivanje je jedan od najčešćih procesa spajanja komponenata u industrijskoj ili proizvodnoj praksi. Njegove glavne prednosti su brzina izrade kombinovana sa niskom cenom i obično sa visokim stepenom fleksibilnosti, integriteta i pouzdanosti. Bez odzira na to, zavarivanje je izuzetno složen metalurški postupak i prema tome, zavareni spojevi su osetljivi na stvaranje prslina, grešaka i zaostale napone, što može dovesti do otkaza konstrukcije i skraćenja veka. Zavarene konstrukcije imaju široku primenu u mnogim granama industrije. U ovom radu je ispitan čelik 15NiMoCrB4-5 čvrstoće popuštanja 668 MPa i zatezne čvrstoće blizu 820 MPa. Ovaj materijal je niskougljenični mikrolegirani čelik legiran niklom i molibdenom, koji se koristi za izradu cevovoda za transport nafte i prirodnog gasa. U takvoj primeni, katastrofalni lom izazvan zamorom uzrokuje iznenadna oštećenja imovine i pogibiju ljudi. Stoga je, sa stanovišta krajnje primene, poznavanje žilavosti loma od ogromne važnosti. Urađena su eksperimentalna ispitivanja na zavarenim spojevima. Od ispitivanja mehanike loma urađeno je ispitivanje žilavosti loma na epruvetama za savijanje u tri tačke. Obrađeni su rezultati izmerene primenjene sile i CMOD da bi se utvrdila vrednost KIC, CTOD ili J-integrala. Stvaranje zamorne prsline i propagacija prsline su merene metodom popuštanja. Izračunate kritične vrednosti, JIC, su upoređene sa vrednostima dobijenim pomoću MKE. Model MKE je definisan na bazi eksperimentalnih uslova u programu Ansys. Cilj ovog istraživanja je bio da se utvrdi uticaj geometrije zavarenih spojeva (različite veličine zona) i položaja prsline na zamorni vek. Najpre su zavareni spojevi napravljeni MIG postupkom i ispitani su u pogledu mehaničkih osobina i osobina zamora. Fokus izučavanja je bio na eksperimentalnoj i numeričkoj analizi, sa posebnim osvrtom na zonu pod uticajem toplote.

Magnets for High Energy Physics applications built to date are generally superconducting magnets, which operate at cryogenic temperatures. The reliability and safety of the applications are entirely dependent on good design which in turn rely heavily on predictable materials performance. Where at these low temperatures the fracture toughness is of importance to be known (alongside mechanical properties such yield and tensile strength). At CERN at the materials and engineering department (EN-MME-MA) a testing facility is being commissioned for the measurement of mechanical at cryogenic temperatures. A tensile test facility has been realised, yet no such set-up is available for fracture toughness measurement. The aim of this thesis was to develop a test set-up for the measurement of the fracture toughness in order to realise a universal cryogenic testing system, which can be used for both tensile tests and fracture toughness test at low temperatures. A design for a set-up is proposed for the measurement of the fracture toughness which can be employed within the current cryostat. The design of the tooling and cryostat have been extensively verified using numerical methods taking into account thermal effects (such as conduction and contraction) and the varying material properties at these low temperatures. A modified C(T) specimen is proposed for more robust and reliable set-up. For this modified specimen it is shown with numerical methods that the modification are expected to have a negligible impact on the fracture toughness measurements. Tests have been performed using the proposed design with four specimen fabricated from two different materials (SS316L and Ti6Al4V), at both room temperature and at 4 K (using liquid helium). The set-up is shown to provide sufficient data for the characterisation of the fracture toughness for both Linear Elastic Fracture Mechanics tests as well as Elastic Plastic Fracture mechanics tests., Mechanical Engineering

Cracks are one of the main problems that plague road workers. A correct understanding of the internal crack propagation mechanism of asphalt pavement will help road workers evaluate the road’s working status more comprehensively and make more reasonable decisions in design, construction, and maintenance work. This paper established a three-dimensional asphalt pavement layered model using the software ABAQUS and fracture mechanics theory and the extended finite element method were used to explore the mechanical response of the pavement base layer’s preset reflective cracks. This paper investigated the influence of the modulus of each layer, vehicle load on the principal stress, shear stress, J-integral, and two stress intensity factors (K1, K2) during the pre-determined crack propagation process of the pavement base layer, and the entropy method was used to analyze the above-mentioned mechanical response. The results show that the main factor affecting the propagation of reflective cracks on asphalt pavements is the modulus of the bottom surface layer. However, from a modeling perspective, the effect of increasing load on crack growth is obvious. Therefore, in terms of technical feasibility, the prevention of reflective cracks should still be achieved by controlling the driving load and prohibiting overloading., Pavement Engineering

In the present study, three-point bending tests are carried out using single-edge notched beam specimens of bitumen and mastic to quantify healing. Experiments are conducted at a controlled displacement rate of 1 mm per minute at -15 degrees C. After the crack propagation, samples are given a rest period of 2 h at 10 degrees C to promote healing before retesting them. Two different analysis approaches appealing to linear elastic fracture mechanics and viscoelastic fracture mechanics are compared. In order to perform analysis based on viscoelastic fracture mechanics, the elastic-viscoelastic correspondence principle is used. The amount of healing after the rest period is quantified using various healing indices based on the recovery of stiffness, peak load, fracture toughness, fracture energy, and J-integral. From the analysis performed on bitumen and mastic samples, the study illustrates that the quantum of healing is different when comparing different healing indices. While the stiffness-based healing index demonstrated the healing ability of bitumen, other healing indices used in the study confirmed the higher healing potential of mastic. The healing based on critical value of J-integral shows a distinct difference in the healing of bitumen and mastic. The study emphasizes that the quantification of healing capacity when using different healing indices should be closely linked to its measured conditions., QC 20220309

The purpose of this study aimed to examine how build orientation and heat treatments affect microstructure, and consequently, the mechanical properties obtained from tensile and fracture toughness tests of additively manufactured AlSi10Mg samples. Samples were manufactured in several orientations using a laser-based powder bed fusion (L-PBF) additive manufacturing (AM) process, following which they were subjected to three separate heat treatments: (i) stress relief at 300 °C for 2 h (SR); (ii) homogenization at 540 °C for 2 h followed by artificial aging at 170 °C for 8 h (HA-1); (iii) homogenization at 540 °C for 6 h followed by artificial aging at 170 °C for 14 h (HA-2). Tensile tests showed that the AB samples presented the highest mechanical strength; however, low ductility was also observed. Therefore, a model for crack propagation during tensile testing was proposed for L-PBF typical microstructure. Samples subjected to fracture toughness tests showed sensitivity to porosity and microstructure. The crack-tip opening displacement (CTOD) of the AB and HA-2 samples showed similar average values of approximately 10 µm in all three orientations. The SR samples showed the best fracture toughness behavior with average values ranging from 19 µm to 32 µm. The HA-1 samples presented average values between 13 µm and 22 µm. The fracture toughness values reported in the J-integral ranged from 6.0 to 8.4 kJ.m-2, 10.4 to 15.5 kJ.m-2, 5.5 to 7.8 kJ.m-2, and 4.6 to 5.7 kJ.m-2, respectively, for the AB, SR, HA-1, and HA-2 heat treatments., Peer Reviewed, Postprint (author's final draft)

In this work two approaches to the description of short fatigue crack growth rate under large-scale yielding condition were comprehensively tested: (i) plastic component of the J-integral and (ii) Polak model of crack propagation. The ability to predict residual fatigue life of bodies with short initial cracks was studied for stainless steels Sanicro 25 and 304L. Despite their coarse microstructure and very different cyclic stress-strain response, the employed continuum mechanics models were found to give satisfactory results. Finite element modeling was used to determine the J-integrals and to simulate the evolution of crack front shapes, which corresponded to the real cracks observed on the fracture surfaces of the specimens. Residual fatigue lives estimated by these models were in good agreement with the number of cycles to failure of individual test specimens strained at various total strain amplitudes. Moreover, the crack growth rates of both investigated materials fell onto the same curve that was previously obtained for other steels with different properties. Such a "master curve" was achieved using the plastic part of J-integral and it has the potential of being an advantageous tool to model the fatigue crack propagation under large-scale yielding regime without a need of any additional experimental data.

In this work two approaches to the description of short fatigue crack growth rate under large-scale yielding condition were comprehensively tested: (i) plastic component of the J-integral and (ii) Polak model of crack propagation. The ability to predict residual fatigue life of bodies with short initial cracks was studied for stainless steels Sanicro 25 and 304L. Despite their coarse microstructure and very different cyclic stress-strain response, the employed continuum mechanics models were found to give satisfactory results. Finite element modeling was used to determine the J-integrals and to simulate the evolution of crack front shapes, which corresponded to the real cracks observed on the fracture surfaces of the specimens. Residual fatigue lives estimated by these models were in good agreement with the number of cycles to failure of individual test specimens strained at various total strain amplitudes. Moreover, the crack growth rates of both investigated materials fell onto the same curve that was previously obtained for other steels with different properties. Such a "master curve" was achieved using the plastic part of J-integral and it has the potential of being an advantageous tool to model the fatigue crack propagation under large-scale yielding regime without a need of any additional experimental data.

In this work two approaches to the description of short fatigue crack growth rate under large-scale yielding condition were comprehensively tested: (i) plastic component of the J-integral and (ii) Polak model of crack propagation. The ability to predict residual fatigue life of bodies with short initial cracks was studied for stainless steels Sanicro 25 and 304L. Despite their coarse microstructure and very different cyclic stress-strain response, the employed continuum mechanics models were found to give satisfactory results. Finite element modeling was used to determine the J-integrals and to simulate the evolution of crack front shapes, which corresponded to the real cracks observed on the fracture surfaces of the specimens. Residual fatigue lives estimated by these models were in good agreement with the number of cycles to failure of individual test specimens strained at various total strain amplitudes. Moreover, the crack growth rates of both investigated materials fell onto the same curve that was previously obtained for other steels with different properties. Such a "master curve" was achieved using the plastic part of J-integral and it has the potential of being an advantageous tool to model the fatigue crack propagation under large-scale yielding regime without a need of any additional experimental data.

The fracture represents the final phase of crack propagation, and the causes of their occurrence or partial crack propagation in the real constructions made of ferritic steels can be different. Along with cracks, influences such as stress concentration and low temperature contribute to fracture being “faster” and have an impact on the fracture mechanics parameters, as well as on the fact that fracture is more likely to occur due to cleavage. The parameters discussed in this study are Jc and rc (parameter, i.e. distance between fatigue crack tip and cleavage initiation site) by testing of C(T)50 specimen in the transition temperature region. Grooved C(T) specimens were made of reactor steel 20MnMoNi 55 with two thickness values, since an additional goal of this study was to present the influence of thickness of tested specimens. Along with it, other parameters that have influence on the understanding of transition temperature region and fracture in this region of ferritic steel are presented.

This paper presents the results and methods used for determining of probability of cleavage fracture toughness of ferritic reactor steel in transition temperature area. The steel tested in this study is steel know as 20MnMoNi 55 by DIN standard, typically used for structures working at low temperatures. In addition, the effect of test specimen geometry, temperature and fatigue crack initiation rate on fracture toughness was investigated in order to predict the fracture behaviour and probability of cleavage fracture. Two main studies joined in on one are presented in this paper. Testing in both studies were performed according to ASTM 1820 standard and the Weibull distribution with regression analysis, which includes fitting the experimental results in a logarithmic coordinate system, was used to predict the Jc values. Cleavage fracture probabilities in the function of Jc for large test specimen, C(T)100 and C(T)200 were determined based on the results obtained by testing of small C(T)50 specimens, for the purpose of direct savings and decreased costs of specimen testing. Cleavage fracture probability, represented by using Weibull distribution of experimental data will provide a clear insight into material behaviour at different temperatures. The influence of Delta K values during fatigue pre-cracking procedure on the fracture toughness scatter was also presented and discussed.

Due to its superior strength at high temperatures P/T91 steel is often applied in the chemical, petrochemical and fossil-fired power generation industries. The high strength is achieved by a suitable martensitic microstructure after appropriate heat treatment procedure. Welding is the most important process of joining the components in such plants, and the heat-affected zone is often the weakest part of these structures. Having in mind that the welded joint is the weakest area, it is necessary to know its properties and assess the level of its degradation. It was found that the life-limiting factor in case of P/T91 steel welded structures are the cracks located in the heat affected zones, more precisely in its intercritical region. In present paper the results of the fracture toughness measurement carried out on simulated P91 steel ICHAZ specimens produced using a weld simulator has been presented. The tests were done on two types of simulated specimens, those subjected to the subsequent PWHT and with those left untreated (without PWHT), at room temperature and 600 degrees C. For the J-integral estimation pin-loaded SEN(T) specimens were tested in plane stress conditions using the unloading compliance method of deriving a single specimen resistance curve and the eta-method.

Cracks are one of the main problems that plague road workers. A correct understanding of the internal crack propagation mechanism of asphalt pavement will help road workers evaluate the road’s working status more comprehensively and make more reasonable decisions in design, construction, and maintenance work. This paper established a three-dimensional asphalt pavement layered model using the software ABAQUS and fracture mechanics theory and the extended finite element method were used to explore the mechanical response of the pavement base layer’s preset reflective cracks. This paper investigated the influence of the modulus of each layer, vehicle load on the principal stress, shear stress, J-integral, and two stress intensity factors (K1, K2) during the pre-determined crack propagation process of the pavement base layer, and the entropy method was used to analyze the above-mentioned mechanical response. The results show that the main factor affecting the propagation of reflective cracks on asphalt pavements is the modulus of the bottom surface layer. However, from a modeling perspective, the effect of increasing load on crack growth is obvious. Therefore, in terms of technical feasibility, the prevention of reflective cracks should still be achieved by controlling the driving load and prohibiting overloading., Pavement Engineering

Magnets for High Energy Physics applications built to date are generally superconducting magnets, which operate at cryogenic temperatures. The reliability and safety of the applications are entirely dependent on good design which in turn rely heavily on predictable materials performance. Where at these low temperatures the fracture toughness is of importance to be known (alongside mechanical properties such yield and tensile strength). At CERN at the materials and engineering department (EN-MME-MA) a testing facility is being commissioned for the measurement of mechanical at cryogenic temperatures. A tensile test facility has been realised, yet no such set-up is available for fracture toughness measurement. The aim of this thesis was to develop a test set-up for the measurement of the fracture toughness in order to realise a universal cryogenic testing system, which can be used for both tensile tests and fracture toughness test at low temperatures. A design for a set-up is proposed for the measurement of the fracture toughness which can be employed within the current cryostat. The design of the tooling and cryostat have been extensively verified using numerical methods taking into account thermal effects (such as conduction and contraction) and the varying material properties at these low temperatures. A modified C(T) specimen is proposed for more robust and reliable set-up. For this modified specimen it is shown with numerical methods that the modification are expected to have a negligible impact on the fracture toughness measurements. Tests have been performed using the proposed design with four specimen fabricated from two different materials (SS316L and Ti6Al4V), at both room temperature and at 4 K (using liquid helium). The set-up is shown to provide sufficient data for the characterisation of the fracture toughness for both Linear Elastic Fracture Mechanics tests as well as Elastic Plastic Fracture mechanics tests., Mechanical Engineering

J-integral is a fracture mechanic parameter that can be used to characterize elastic-plastic fracture mechanic (EPFM) behavior. The path independent characteristic in J-integral is proposed by Rice [1], and it is widely used in a lot of research. Another approach is the load-displacement approach, where the J-integral is calculated by the area under the load-displacement curve. However, the validity of the J-integral value by load-displacement approach is yet to be confirmed. This paper is aimed to investigate the effect of crack length ratio of CT specimen to J-integral value by two approaches: path-integral approach and load-displacement approach. Finite element analysis of compact tension (CT) model with crack length ratio a/W between 0.2 to 0.5 was carried out under displacement δ between 0.2 to 1.0 mm using ANSYS parametric design language (APDL). The J value by path integral approach, Jpath is compared to the value calculated from load-displacement approach, Jp-d. It was found that path independency occurs for J value evaluated from path integral approach. A correction factor needs to be introduced since the load-displacement approach cannot be used for shallow crack cases.

This paper numerically investigates inelastic behavior of sandstone for better understanding of hydraulic fracture propagation in georeservoirs. Although many numerical, theoretical, and experimental studies investigated hydraulic fracturing, not enough emphasis has been given to the inelastic behavior of rock prior and during the hydraulic fracture propagation. Current practice widely uses linear elastic fracture mechanics (LEFM) principles for prediction of hydraulic fracturing in weak sandstone. However, discrepancies between LEFM models and filed or laboratory results indicate presence of plastic deformation, such as are for example micro-cracks or acoustic emission cloud data. Therefore, this study uses J-integral for obtaining hydraulic fracture propagation criteria under the elastic-plastic stress-strain state. J-integral is calculated on the path around a DEM model in two-dimensions. A synthetic rock mass modeled in DEM has an advantage of time-stepping and stress-strain redistribution which leads to micro-cracks represented by broken bonds between DEM particles, and therefore models well elastoplastic behavior. The relationship between far-field stress magnitudes and breakdown pressures, process zone length and calculated J-integral values are presented. The relationship between crack driving forces and applied stresses is investigated to better understand the plasticity effects. The influence of stiffness of sandstone on breakdown pressures and J-integral values are also studied. Overall, results show that LEFM is not applicable for describing fracture propagation at higher confinement stresses. Inelastic J-integral increases dramatically with rock confinement, especially its plastic portion.

Most of the serious weldment failures lead to catastrophic consequences in terms of damage of other equipment, loss of production, and risks to workers' health and safety. Hence, there is motivation to find margin between safety and disaster. This necessitates guaranteeing the integrity of a welded structure even if a crack is present. Therefore, influence of the material inhomogeneity and residual stresses on deformation and fracture behavior needs to be described precisely. Fracture mechanics parameters J - integral and CTOD have attracted great interest in recent years. Two three point bending specimens of base metal (BM) and weld metal (WM) were tested according to standard BS EN ISO 15653. Than, a two dimensional finite element analysis was performed in Ansys Workbench software to calculate J-integral, and compare with experimental results. The aim of this work is to explore the possibility of using the test results in the reliable prediction of weldment fracture.

The concept of ‘contact stress’, as introduced by Cauchy, is a special case of a nonlocal stress tensor. In this work, the nonlocal stress tensor is derived through implementation of the bond-based formulation of peridynamics that uses an idealised model of interaction between points as bonds. The method is sufficiently general and can be implemented to study stress states in problems containing stress concentration, singularity, or discontinuities. Two case studies are presented, to study stress concentration around a circular hole in a square plate and conventionally singular stress fields in the vicinity of a sharp crack tip. The peridynamic stress tensor is compared with finite element approximations and available analytical solutions. It is shown that peridynamics is capable of capturing both shear and direct stresses and the results obtained correlate well with those obtained using analytical solutions and finite element approximations. A built-in MATLAB code is developed and used to construct a 2D peridynamic grid and subsequently approximate the solution of the peridynamic equation of motion. The stress tensor is then obtained using the tensorial product of bond force projections for bonds that geometrically pass through the point. To evaluate the accuracy of the predicted stresses near a crack tip, the J-integral value is computed using both a direct contour approximation and the equivalent domain integral method. In the formulation of the contour approximation, bond forces are used directly while the proposed peridynamic stress tensor is used for the domain method. The J-integral values computed are compared with those obtained by the finite element package Abaqus 2018. The comparison provides an indication on the accurate prediction of the state of stress near the crack tip.

In this paper, the parameters of fatigue crack growth rate for Q355J2 steel exposed to air and seawater were presented using the “Paris' law” based on the stress intensity factor (SIF), J-integral, crack tip opening displacement (CTOD) and crack tip opening angle (CTOA). The residual stress of a compact tension specimen is analysed by modelling of the welding process based on subsequently thermal mechanical stress analysis. Effect of the residual stresses on the fatigue crack growth rate is investigated by considering the numerically predicted residual stress distribution due to welding. The fatigue crack growth rate based on the parent material considering residual stress effects is compared with welds and the heat affected zone (HAZ)., Steel & Composite Structures

This paper numerically investigates inelastic behavior of sandstone for better understanding of hydraulic fracture propagation in georeservoirs. Although many numerical, theoretical, and experimental studies investigated hydraulic fracturing, not enough emphasis has been given to the inelastic behavior of rock prior and during the hydraulic fracture propagation. Current practice widely uses linear elastic fracture mechanics (LEFM) principles for prediction of hydraulic fracturing in weak sandstone. However, discrepancies between LEFM models and filed or laboratory results indicate presence of plastic deformation, such as are for example micro-cracks or acoustic emission cloud data. Therefore, this study uses J-integral for obtaining hydraulic fracture propagation criteria under the elastic-plastic stress-strain state. J-integral is calculated on the path around a DEM model in two-dimensions. A synthetic rock mass modeled in DEM has an advantage of time-stepping and stress-strain redistribution which leads to micro-cracks represented by broken bonds between DEM particles, and therefore models well elastoplastic behavior. The relationship between far-field stress magnitudes and breakdown pressures, process zone length and calculated J-integral values are presented. The relationship between crack driving forces and applied stresses is investigated to better understand the plasticity effects. The influence of stiffness of sandstone on breakdown pressures and J-integral values are also studied. Overall, results show that LEFM is not applicable for describing fracture propagation at higher confinement stresses. Inelastic J-integral increases dramatically with rock confinement, especially its plastic portion.

Most of the serious weldment failures lead to catastrophic consequences in terms of damage of other equipment, loss of production, and risks to workers' health and safety. Hence, there is motivation to find margin between safety and disaster. This necessitates guaranteeing the integrity of a welded structure even if a crack is present. Therefore, influence of the material inhomogeneity and residual stresses on deformation and fracture behavior needs to be described precisely. Fracture mechanics parameters J - integral and CTOD have attracted great interest in recent years. Two three point bending specimens of base metal (BM) and weld metal (WM) were tested according to standard BS EN ISO 15653. Than, a two dimensional finite element analysis was performed in Ansys Workbench software to calculate J-integral, and compare with experimental results. The aim of this work is to explore the possibility of using the test results in the reliable prediction of weldment fracture.

This works deals with crack growth investigations of tire tread compounds in laboratory. These measurements are usually performed with the Tear Fatigue Analyzer. In the Tear Fatigue Analyzer notched strip samples are loaded dynamically and the resulting crack growth rate dc/dn is measured. This way the crack growth rate dc/dn in dependence of tearing energy T can be determined for a compound under specific loading condition. The tearing energy T describes the energy available for crack growth and can be calculated for different sample geometries. This energy depends particularly on the stored energy density that is caused by straining the sample. Thereby the crack growth rate depends on the used rubbers. Natural rubber, partially crystallizing under strain, shows clearly lower crack growth than the synthetic butadiene and styrene-butadiene rubbers. Using active fillers like carbon black leads to strongly decreased crack growth due to the multiple interactions between filler and polymer matrix. The crack growth in a polymer blend depends also on the morphology of the distinct polymer phases and the magnitude of the interphase. Also the filler distribution into the different polymer phases and the interphase is influencing the crack growth properties. The dynamic mechanical method used to determine the filler distribution is based on the increase of loss modulus due to the filler but the results are influenced by crystallization of the butadiene rubber. The theoretic description of tearing energy in dependence of crack velocity was developed for steady tearing at constant crack velocity. It can be demonstrated that these concepts can be transferred to the dynamic crack growth of unfilled rubber, partially also to the dynamic crack growth of filled rubber. When applying the tearing energy on elastomers it should be noticed that only a small fraction of this energy is reaching the process zone at the crack tip. The decrease of tearing energy towards the crack tip can be

The fracture toughness of four advanced high strength steel (AHSS) thin sheets is evaluated through different characterization methodologies, with the aim of identifying the most relevant toughness parameters to describe their fracture resistance. The investigated steels are: a Complex Phase steel, a Dual Phase steel, a Trip-Aided Bainitic Ferritic steel and a Quenching and Partitioning steel. Their crack initiation and propagation resistance is assessed by means of J-integral measurements, essential work of fracture tests and Kahn-type tear tests. The results obtained from the different methodologies are compared and discussed, and the influence of different parameters such as specimen geometry or notch radius is investigated. Crack initiation resistance parameters are shown to be independent of the specimen geometry and the testing method. However, significant differences are found in the crack propagation resistance values. The results show that, when there is a significant energetic contribution from necking during crack propagation, the specific essential work of fracture (we) better describes the overall fracture resistance of thin AHSS sheets than JC. In contrast, energy values obtained from tear tests overestimate the crack propagation resistance and provide a poor estimation of AHSS fracture performance. we is concluded to be the most suitable parameter to describe the global fracture behaviour of AHSS sheets and it is presented as a key property for new material design and optimization., Peer Reviewed, Postprint (author's final draft)

This paper presents the results and methods used for determining of fracture toughness of reactor steel, denoted as 20MnMoNi55, typically used for structures working at low temperatures, in transition temperature area. In addition, the effect of test specimen geometry and temperature on fracture toughness was investigated in order to predict the fracture behavior and probability of failure. Failure probabilities (i.e. cleavage fracture) in the function of J(c) for large test specimens, CT100 and CT200 were determined based on the results obtained by testing of small CT50 specimens, for the purpose of direct savings and decreased costs of specimen testing. Failure probability, represented using Weibull distribution of experimental data, will provide a clear insight into material behavior at different temperatures. Other factors affecting the obtained test results will also be discussed.

This paper is written on the occasion of J.R. Rice's 80th birthday. Basically, it presents two aspects of interface fracture mechanics, linear elastic and elasto-plastic, both of them reflecting the long experience of the two authors. Special attention has been focused on the seminal contribution of Jim Rice, still being a great inspiration to researchers in the field of fracture mechanics. Fundamentals that he developed enabled us to build versatile scientific and engineering tools that currently enable the solution of almost any problem related to cracks.

Most of the serious weldment failures lead to catastrophic consequences in terms of damage of other equipment, loss of production, and risks to workers' health and safety. Hence, there is motivation to find margin between safety and disaster. This necessitates guaranteeing the integrity of a welded structure even if a crack is present. Therefore, influence of the material inhomogeneity and residual stresses on deformation and fracture behavior needs to be described precisely. Fracture mechanics parameters J - integral and CTOD have attracted great interest in recent years. Two three point bending specimens of base metal (BM) and weld metal (WM) were tested according to standard BS EN ISO 15653. Than, a two dimensional finite element analysis was performed in Ansys Workbench software to calculate J-integral, and compare with experimental results. The aim of this work is to explore the possibility of using the test results in the reliable prediction of weldment fracture.

Most of the serious weldment failures lead to catastrophic consequences in terms of damage of other equipment, loss of production, and risks to workers' health and safety. Hence, there is motivation to find margin between safety and disaster. This necessitates guaranteeing the integrity of a welded structure even if a crack is present. Therefore, influence of the material inhomogeneity and residual stresses on deformation and fracture behavior needs to be described precisely. Fracture mechanics parameters J - integral and CTOD have attracted great interest in recent years. Two three point bending specimens of base metal (BM) and weld metal (WM) were tested according to standard BS EN ISO 15653. Than, a two dimensional finite element analysis was performed in Ansys Workbench software to calculate J-integral, and compare with experimental results. The aim of this work is to explore the possibility of using the test results in the reliable prediction of weldment fracture.

Most of the serious weldment failures lead to catastrophic consequences in terms of damage of other equipment, loss of production, and risks to workers' health and safety. Hence, there is motivation to find margin between safety and disaster. This necessitates guaranteeing the integrity of a welded structure even if a crack is present. Therefore, influence of the material inhomogeneity and residual stresses on deformation and fracture behavior needs to be described precisely. Fracture mechanics parameters J - integral and CTOD have attracted great interest in recent years. Two three point bending specimens of base metal (BM) and weld metal (WM) were tested according to standard BS EN ISO 15653. Than, a two dimensional finite element analysis was performed in Ansys Workbench software to calculate J-integral, and compare with experimental results. The aim of this work is to explore the possibility of using the test results in the reliable prediction of weldment fracture.