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Welded components are highly vulnerable to fatigue failures due to stress concentrations and material imperfections. This study develops an analytical framework that predicts both high‐cycle (HCF) and low‐cycle (LCF) fatigue lives of welded joints using a structural strain parameter. By employing a linear hardening model, the method effectively translates structural stress into structural strain, providing a reliable metric for assessing fatigue life, especially in LCF conditions. Validated against experimental data from 62 longitudinal gusset joints, the approach proves both reliable and practical. This simplified method facilitates easier fatigue assessments, encouraging its wider use and potential standardization in engineering, thus improving the predictability of welded structures' performance. Highlights: An analytical framework is presented to assess the fatigue behavior of welded structures.The linear hardening law is introduced to capture the material hardening behavior.The analytical solutions for plane stress and plane strain conditions are provided.The method is applied to analyze 62 weldment fatigue data in both HCF and LCF regime. [ABSTRACT FROM AUTHOR]

High-strength advanced steel and welded structure are key for service safety and life. Static and dynamic compressive mechanical behavior of high-strength 22SiMn2TiB armor steel and welded structure is investigated, which are carried out by using universal testing machine and split Hopkinson pressure bar. The studied materials are obtained from high-strength steel matrix, welded seam and mix of them with interface, respectively. The strain rate in experiments covers the range of 0.001/s to 6000/s. The mechanical data involve stress-strain relations and strain rate dependencies of mechanical properties. The cracking behavior as well as the corresponding microstructures are characterized at different length scales from millimeter to micron scale by optical microscope and scanning electron microscope. The results show that static (0.001/s) and dynamic (5000/s) yield strengths are 1600 MPa and 2400 MPa for high-strength steel matrix, 400 MPa and 1200 MPa for welded seam, 950 MPa and 1600 MPa for mix of them with interface, respectively. Under dynamic loading, shearing occurs and results in the fracture. Along the interface of steel matrix and welded seam, cracks are firstly initiated and propagated. The relations of mechanical properties and fracture features are analyzed, where strain rate effect is mentioned. This work will guide the design and application for engineering structure.

Copyright of China Mechanical Engineering is the property of Editorial Board of China Mechanical Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The prediction of fatigue life and the assessment of resistance in welded structures are crucial aspects in the field of structural and mechanical engineering, especially in the design of vehicle structures. In this paper, a three-dimensional numerical model was developed using the ANSYS software to investigate the static and fatigue behavior of a simplified quarter vehicle model subjected to damped loads. Static load applied to the chassis, structure thickness, weld bead thickness, spring stiff-ness, and speed bump amplitude have a significant impact on the durability of our welded design, which represents the vehicle chassis. The objective of this study is to validate and compare the numerical results with experimental tests through parametric studies. We aim to evaluate the influence of various parameters on the reliability and durability of the welded structure. To achieve this, a scaled-down test bench was designed and constructed to measure the rigidity and durability of the structures under static and dynamic loads. The experimental results obtained align well with the developed models, exhibiting an error rate below 10%. [ABSTRACT FROM AUTHOR]

Copyright of China Mechanical Engineering is the property of Editorial Board of China Mechanical Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Purpose: This paper aims to present an engineering computational method for fatigue life evaluation of welded structures on large-scale equipment under random vibration load. Design/methodology/approach: Based on a case study of the traction transformers, virtual fatigue test (VFT) was proposed via numerical simulation approach. Static analysis was conducted to identify the risky zone and then dynamic response of the risky welds under random vibration load was calculated based on frequency-domain structural stress method (FDSSM) theory, life distribution and associated survivability at various locations of the structure were obtained. Structural modification was finally performed according to the evaluation results. Moreover, experimental test was carried out and compared with the virtual test result. Findings: By applying the virtual test, fatigue life of the complex welded structures on large-scale equipment can be accurately and efficiently obtained considering dynamic effect under random vibration load. Meanwhile, risky welds can be directly determined and targeted modification scheme can be accordingly concluded. Validity of the VFT result was proved by comparing with the experimental test. Originality/value: The proposed method can help obtain equivalent structural stress and fatigue life distribution of the welded structure at any position with various survivability and make quantitative evaluation on the life-extending effect of the structural modification. This method shows significant cost and efficiency advantages over experimental test during design stage of the large-scale structures in numerous manufacturing industries. [ABSTRACT FROM AUTHOR]

In the present paper, a three‐dimensional numerical model has been built using ANSYS code to analyze the static and fatigue behavior of a welded design based on four rectangular profiles under damped loads for automotive application. The fatigue of the proposed design is generally influenced by a number of factors. The aim of this study is to investigate the effect of the load level, the stress ratio, the mean stress theory, the geometry size, the weld bead height, the temperature of the weld bead on the durability (P1), and the maximum of von Mises stress (P2) at the critical areas in the welded structure. As well as the length and the stiffness of the spring have been furtherly investigated. For this purpose, the application of the Taguchi method with computational simulation was performed for the target to determine the optimum operating parameters conditions. The results indicated that the optimum levels yielding a higher performance for P1 and P2 were (L1, L2, L2, L3, L1, L1, L3, and L3) and (L2, L3, L3, L3, L3, L3, L3, and L2), respectively. Thus, it revealed that the weld temperature was the predominant parameter influencing P1 and the mean stress theory factor was the most significant parameter influencing P2. This study led to defining a regression equation relating the output parameters with the selected factors. Consequently, the percentage error between regression equation calculations and computational outputs of fatigue life and maximum von Mises stress corresponding to the most optimal combinations obtained from Taguchi calculations was 0.92% and 0.63%, respectively. In fact, several parameters have been employed in this durability assessment to characterize the behavior of welded rectangular profiles prototype to predict the overall behavior of the suspension system of the automotive. [ABSTRACT FROM AUTHOR]

The overall stiffness and modal frequency of the car body of a rapid box car are reduced by the design of the full-side open movable side door structure. The vibration fatigue performance of the welded structure in this car body needs to be verified. The rigid-flexible coupling model of the rapid box wagon was established first, and the model was verified by modal test data. By the application of the virtual iteration method on this model, the displacement excitation loads of this vehicle were acquired. The effectiveness of the load reverse obtaining technology was verified through the comparison between calculated data and the experimental data. Based on the rigid-flexible coupling model and the load obtained by reverse engineering, the fatigue life of the welded structure in the car body was evaluated through the modal structural stress method. The calculated results show that the car body structure obtains obvious modal vibration, which leads to short fatigue life in several weld lines. According to the application requirements of this wagon, the local improvement scheme was proposed, and the effect of the improvement program was evaluated. In this paper, a new fatigue evaluation technology based on the load reverse method of test data was proposed, which provides a theoretical basis for the structural design and program improvement of railway vehicles. [ABSTRACT FROM AUTHOR]

In this paper, a new fatigue life evaluation method, namely augmented-reverse notch equivalent stress method, is proposed for titanium alloy welded structures with stress singularities. First, a new three-parameter power function model is proposed in this paper, and the notch stress equivalent value method with correction factor is deduced. Combining the two, the theoretical framework of the augmented-reverse notch equivalent stress method is obtained. Within this framework, the fatigue test data of four titanium alloy welded joints with the same grade were used for analysis, and a new three-parameter power function model of titanium alloy welded structure was established. According to the calculation method of the notch equivalent stress correction factor, the correction factor suitable for the titanium alloy welded structure was obtained. Finally, the fatigue test data, different from the above titanium alloy welded structure, are used to verify the augmented-reverse notch equivalent stress method. The verification results show that the augmented-reverse notch equivalent stress method improves the effectiveness and accuracy of fatigue life evaluation and establishes a new life evaluation method for titanium alloy welded structures with stress singularities. [ABSTRACT FROM AUTHOR]

With the increase in material and labour costs, the optimization of welded steel structures is gradually becoming a necessity. Precise cost calculation methods are a prerequisite for the optimization process; they enable the designers to differentiate between product variations and select the best one. However, while the calculation of the material cost is simple, the calculation of fabrication costs, which include the costs of cutting, handling, welding, and surface preparation, is harder to define. Thus, in this paper, two available cost calculation methods are compared by observing two specific welded structures: a welded I beam and a gearbox housing. Both the total and the partial costs were compared. Based on the results, it was concluded that the methods are in agreement considering the total cost values and that both methods can differentiate between the design variations comparably. On the other hand, partial costs of process segments differed, mostly due to variations in the predefined scope of each process (e.g., one method included handling in the material costs, while the other included it in the welding costs). [ABSTRACT FROM AUTHOR]

In order to investigate the material properties of the welded structure in the airship and the effect of the welded structure on the membrane strength,the test specimens and schemes were designed for uniaxial tensile test,uniaxial cyclic test,and biaxial tensile test according to the airship engineering experience and structural stress distribution. The method of digital image correlation was adopted in the experiment. The test results show that the strength of welded structure is more than membrane and the fracture location is the membrane where the two materials meet. The strength of membrane with welded structure is smaller than the membrane itself,which is reduced by about 12% under uniaxial tensile condition and reduced by about 36% under biaxial tensile condition with ratio 2 ∶1. This paper can provide experimental support for the strength prediction of the airship structure.

To calculate the fatigue strength of complex handle welded structure under cyclic loading,the stress time history of handle component under cyclic loading was solved using transient modal dynamic analysis method,and the fatigue life of welded structure was calculated using mesh-size insensitive Battlle structural stress approach.It was found that the fatigue strength of original handle welded structure is insufficient because the ear plate connection structure is inconsistent,which results in stress concentration.The transition plate was added to the improved welded structure and the calculation result shows the maximum structural stress near the weld lines is 44.9% lower than that of the original structure,and the stress is relatively uniform.The fatigue life of the improved one was estimated to be 4 years and 5 months.The weld failure of improved welded structure has not occurred for more than 3 years in service in two equipments,which meets the application requirements.For large welded structures which are difficult to conduct physical tests,the numerical calculation based on Battlle structural stress approach can provide a basis for structural design.

Whilst verifying the quality of welded joints in railway bridges in Poland, it was found that many of them contained cracks of technological, fracture and fatigue origin. This problem is associated with early welded bridge structures, in which many technological imperfections were discovered. General data for x‐ray testing on approximately 200 bridges in service are given. The tests were carried out over the period 1967–1990. The number of joints tested was 15 875 and the number of cracks discovered in the joints was 437 in the 34 bridges tested. Repeated tests on the joints containing cracks in time intervals of 5–8 years neither demonstrated further growth in the cracks nor the formation of new cracks. All the cracks discovered were formed during welding operations where there was no service loading. An analysis of the stress levels necessary for the development of crack growth was carried out via fatigue laboratory tests on three butt splice models which were similar to the joints in the bridges tested. Concurrently, the probable stress level near to the cracks was determined analytically. The calculated and measured stresses under service loadings did not exceed empirically assessed weld endurance limits for these joints and confirmed no crack growth. Hot cracks and other welding imperfections in welded joints in structures are permissible if there is neither growth in service nor resistance or rigidity loss of the structure. [ABSTRACT FROM AUTHOR]

This paper proposes an effective numerical method to predict welding distortion for large welded structures. To predict welding distortions, inherent strain-based methods are computationally efficient and widely used in engineering fields. However, there are some drawbacks such as the generation of undesirable longitudinal forces and the use of vector-type input variables. Equivalent loads are derived through finite element formulation considering orthotropic thermal expansion conditions. Unlike previous methods, the proposed method predicts transverse shrinkage and angular distortion accurately, removing the undesirable longitudinal forces. In addition, scalar-type input variables are employed, which results in a convenient design procedure. The performance of the proposed method is verified through various examples including complex and large welded structures. [ABSTRACT FROM AUTHOR]

In keeping with DSTU ISO 9001:2015 standard, an organization should develop, document, introduce and maintain in the working condition a system of quality management, and should constantly improve its effectiveness, in keeping with the requirements of the actual standard. [ABSTRACT FROM AUTHOR]

Current state of international and state technical regulation was analyzed. Ukraine is taking a number of important steps, in order to bring Ukrainian legislation in the field of technical regulation to the level of international requirements. Proceeding from analysis of normative documents, it was determined, which welded products are covered by technical regulations, harmonized with European Directives, which are mandatory for application. Orders of the respective Ministries are indicated, which determine the lists of standards, compliance with which confirm the correspondence to requirements of technical regulations. It is defined that assessment of the compliance of critical welded products is performed with application of a combination of modules, a component of which is certification of quality management system. The field of normative documents was analyzed in terms of specific requirements to quality management system that apply in different industries. The plan of action was determined for welding production plants, which has the objective to introduce measures to ensure product compliance with the requirements of technical regulations. 6 Ref., 1 Tabl. [ABSTRACT FROM AUTHOR]

• Examination of the application of an FEM-based numerical method for obtaining fatigue parameters. • Simulation-based fatigue assessment of welded joints using the 4R method. • Simulation of welding-induced residual stresses and deformations of a welded joint. The increased tensile strength capacity of high-strength steels (HSS) can be utilized fully in static loads, for fluctuating loads, however, more detailed analysis of design and manufacturing is needed. This study presents a framework for investigating utilization of the finite element method (FEM) in multiparametric 4R method-based fatigue evaluation. More specifically, the aim of the current study is to produce a concept for determining the parameters of the 4R method using FEM, thus providing a tool for evaluating fatigue strength related factors numerically. The study examines gas metal arc welded (GMAW) longitudinal gusset joints made of HSS S700MC Plus. The simulation is carried out as a sequentially coupled welding analysis that includes material condition changes in the HAZ and the fluctuating response as a restart analysis. Experimental measurement is performed for comparison with the results of the numerical model in the intermediate stages of the analysis process, and in the final stage as regards fatigue life. The experimental and simulated sub-results are consistent, and the estimated fatigue lives are in relatively good agreement with the experimental fatigue results. The numerical method thus provides a tool to predict fatigue related factors considered in 4R to evaluate fatigue life of welded joints. [ABSTRACT FROM AUTHOR]

In this paper, a new fatigue life evaluation method, namely augmented-reverse notch equivalent stress method, is proposed for titanium alloy welded structures with stress singularities. First, a new three-parameter power function model is proposed in this paper, and the notch stress equivalent value method with correction factor is deduced. Combining the two, the theoretical framework of the augmented-reverse notch equivalent stress method is obtained. Within this framework, the fatigue test data of four titanium alloy welded joints with the same grade were used for analysis, and a new three-parameter power function model of titanium alloy welded structure was established. According to the calculation method of the notch equivalent stress correction factor, the correction factor suitable for the titanium alloy welded structure was obtained. Finally, the fatigue test data, different from the above titanium alloy welded structure, are used to verify the augmented-reverse notch equivalent stress method. The verification results show that the augmented-reverse notch equivalent stress method improves the effectiveness and accuracy of fatigue life evaluation and establishes a new life evaluation method for titanium alloy welded structures with stress singularities.

Welding is a consolidated technology used to manufacture/assemble large products and structures. Currently, welding design issues are tackled downstream of the 3D modeling, lacking concurrent development of design and manufacturing engineering activities. This study aims to define a method to formalize welding knowledge that can be reused as a base for the development of an engineering design platform, applying design for assembly method to assure product manufacturability and welding operations (design for welding (DFW)). The method of ontology (rule-based system) is used to translate tacit knowledge into explicit knowledge, while geometrical feature recognition with parametric modeling is adopted to couple geometrical information with the identification of welding issues. Results show how, within the design phase, manufacturing issues related to the welding operations can be identified and fixed. Two metal structures (a jack adapter of a heavy-duty prop and a lateral frame of a bracket structure) fabricated with arc welding processes were used as case studies and the following benefits were highlighted: (i) anticipation of welding issues related to the product geometry and (ii) reduction of effort and time required for the design review. In conclusion, this research moves forward toward the direction of concurrent engineering, closing the gap between design and manufacturing. [ABSTRACT FROM AUTHOR]

In this paper, we describe the concept of setting the base of large-sized parts with a diameter of up to 8300 mm and a mass of up to 120 tons, such as a bandage of a rotating cement kiln during machining using a mobile robotic machine. The issue of controlled cutting to ensure accurate shaping of a large-sized part with a thickness of the removed metal layer up to 6 mm is considered. Processing is conducted by the method of power grinding using a special tool: an abrasive belt. Rigidity in the "part–tool" system is ensured by the local method of rigid support. [ABSTRACT FROM AUTHOR]

The article characterises the sea-going vessel hull assembly processes and then reviews the existing assembly methods of mechanisms and welded ship structures. Classification of these methods is done with respect to selected criteria of their applicability to hull assembly. Selected methods are used for calculations performed on a model structure and exemplary database. The analysed aspects include the performance of calculation algorithms and the quality of the obtained solutions. Particular attention is paid to the need for reduction of experts’ participation in the planning process due to strong search space explosion effect. The performed analyses have enabled the authors to formulate assumptions for models which would be applicable in real assembly planning in shipyards, as well as to indicate areas of further research which would make it possible to better consider the specificity of production of large-size welded structures.

Copyright of Journal of Architecture & Civil Engineering is the property of Chang'an Daxue Zazhishe and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Chinese Journal of Computational Mechanics / Jisuan Lixue Xuebao is the property of Chinese Journal of Computational Mechanics Editorial Office, Dalian University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In keeping with mandatory requirements of technical procedures to technical documents for critical products of welding fabrication, the technical documentation should allow assessment of product compliance with regulatory requirements and should include a description of performance and results of proper analysis and assessment of risk (risks). At present there is no reliable method for assessing the welded structure risk. The paper identifies the features of risk occurrence during the product life cycle. The algorithm of occurrence of components of risk in welded structure operation, which is the aggregate of both the risks connected with deviations of the processes of design, manufacture, and operation (in other words, those connected with the processes of product life cycle), and the risks associated with dangers, which arise from impacts on the structures and the probability of the structure operation outside its application limits. It is noted that the risk in operation is the probability that the structure will reach the limit state during the specified period of operation. The limit states are divided into two groups. The fi rst group includes limit states, the transition through which leads to complete unsuitability of the object. The second group includes those that complicate the normal operation of the object or shorten its service life, compared to the specified term. During operation, the welded metal building structure is exposed, first of all, to mechanical and corrosion impacts. References to the theory and formulas are given that determine the probabilities of a metal structure failure. It is recommended to use the Bayesian formula to calculate the total value of operational risk. 17 Ref., 8 Tabl., 4 Fig. [ABSTRACT FROM AUTHOR]

Accidents occurring on railway track of 1520 nun are often associated with the fracture of cast load-carrying elements of three-element freight car trucks. The level of quality and endurance of such truck elements as side frame and truck bolster, which are traditionally manufactured by casting technology, are insufficient, so it is advisable to use welding technology to manufacture the mentioned parts of sheet rolled metal in order to increase the fatigue resistance characteristics. The development of a new all-welded structure of side frame of a three-element freight car truck with an axial load of 23.5 tc was carried out on the basis of widespread use of mathematical modelling to determine the stress-strain state of welded elements of the truck under the action of a regulated range of loads and to evaluate the strength according to the valid standards and modem global approaches. The technology of assembly and welding, as well as the appropriate specialized equipment for manufacture of a developed design of welded side frame were created. Two test specimens were manufactured and accelerated fatigue tests were carried out. the results of which showed a significant increase in endurance and vitality under operational cyclic loads as compared to designs of existing cast side frames. Taking into account high values of reliability, availability and manufacturability, ability of a significant reduction in unsprung weight and increase in dimensional accuracy, the welded structure of the side frame of a three-element freight car truck is very promising for its implementation on railway track of 1520 mm. [ABSTRACT FROM AUTHOR]

The accidents occurring on railway track of 1520 mm are often associated with the fracture of cast load-carrying elements of three-element freight car bogies. The level of quality and endurance of such bogie elements as side frame and bogie bolster, which are traditionally manufactured by casting technology, are insufficient, so it is advisable to use welding technology to manufacture the mentioned parts of sheet rolled metal in order to increase the fatigue resistance characteristics. The development of a new all-welded structure of side frame of a three-element freight car bogie with an axial load of 23.5 ts was carried out on the basis of widespread use of mathematical modelling to determine the stress-strain state of welded elements of the bogie under the action of a regulated range of loads and to evaluate the strength according to the valid standards and modem global approaches. The technology of assembly and welding, as well as the appropriate specialized equipment for manufacture of a developed design of welded side frame were created. Two test specimens were manufactured and accelerated fatigue tests were carried out, the results of which showed a significant increase in endurance and vitality under operational cyclic loads as compared to designs of existing cast side frames. Taking into account high values of reliability, availability and manufacturability, ability of a significant reduction in unsprung weight and increase in dimensional accuracy, the welded structure of the side frame of a three-element freight car bogie is very promising for its implementation on railway track of 1520 mm. [ABSTRACT FROM AUTHOR]

The objective of this review regarding the catastrophic failure of an important welded structure, the Alexander L. Kielland platform, was to indicate that the investigation team should have comprised and involved an experienced welding engineer. Lack of involvement of the welding engineer can lead to misinterpretation of the evidence which results in the incorrect identification of the cause of failure. In this case, the Alexander L. Kielland platform, only the mechanism of failure, which was by fatigue, was correctly identified by the investigation team, this review by the author has correctly identified the true causes that lead to catastrophic failure. Derived from identification of the true causes, i.e. a need for more appropriate design criteria and suitable welding protocols, then by the rectification of these causes, we can suppress the vulnerability of the structure to these modes of fatigue failure operating. The result of this review should therefore be welcomed by anyone concerned with design, construction and the health and safety of operation of these types of welded structure. [ABSTRACT FROM AUTHOR]

There is a growing interest in developing upconversion nanocrystals at the forefront of promising applications. However, insufficient energy transfer between lanthanide ions still limited the practical application. In this work, a new class of welded-structure upconversion nanoparticles which emits bright green emission upon 980 nm near-infrared (NIR) laser excitation is presented. Importantly, this unique welded-structure arrangement enables the high-efficient energy transfer between different nanocrystals, leading to 65-folds enhancement for green upconversion emission. A continuous wave 980 nm laser is used to reduce interparticle distance followed by structure welding. The experiment findings show that the controlling distance of nanosheets enables readily manipulation the intensity ration of green and red emission, thereby allowing us to achieve the emission color purity tuning from pea green to bright green. And the green and red ratio achieved 11 folds enhancement, leading to a purer green light emission. The result not only provide an upfront experimental design for constructing welded-nanostructures with efficient energy transfer and color purity tunability, but also suggests a new pathway to build high-efficiency upconversion systems. In this work, the irradiation time-dependent upconversion emission was achieved via controlling the interparticles distance. This unique structure arrangement simultaneously enables the high-efficient energy transfer between different nanocrystals and achieves readily manipulation of the color purity, leading to 65-folds enhancement for green upconversion emission. Image 1 • Laser triggered controllable interparticle distance and structure welding. • Unique structure arrangement enables the high-efficient energy transfer. • Controlling distance enables readily manipulation tunable UC colors. • Simultaneous enhancing UC intensity, lifetime, and color purity. [ABSTRACT FROM AUTHOR]

Welded high-strength bolts are recently being applied to automobile part fixations, and it is important to clarify their fatigue behaviours and to carry out the fatigue strength designs for preventing fatigue failures. Using the spot and full-circled welded bracket samples in four kinds of weld shapes, bending fatigue strength properties of welded high-strength bolt structures were examined. Factors affecting fatigue to failure, such as weld bead shapes and metal structures, were identified through local stress measurements with strain gauges and X-ray diffractions, microscope observations and chemical composition analyses, as well as stress concentrations of finite element method computational simulation. Differences of bending fatigue strengths at 2 × 105 cycles in welded bolt structure samples when based on nominal stress are 15% to 60% compared with the bolt itself. Fatigue strengths corresponded to four kinds of fracture modes and did not decline greatly in the full-circled welded structure. The spot P sample, in which the connecting line between the two centres of the weld beads was perpendicular to the load direction, has higher strength due to the crack initiating from the weld zone of the gap between the plate and the bolt flange which has hard mixed phases of ferrite + martensite + bainite with high fatigue resistance, and its strength divided by weld length does not deteriorate. The strengths and fracture modes were analysed from the viewpoints of the shape effect relating to the stress concentration and residual stress and the material effect relating to the microstructure of the weld as well. [ABSTRACT FROM AUTHOR]

In order to improve the fatigue performance of a welded A-type frame in a heavy off-road mining truck, a novel method was presented to implement lifetime and weight collaborative optimization while considering uncertainties in geometry dimension, material properties, and bearing load. The mechanical and cyclic material parameters were obtained from experimental work to characterize the base metal and the weldment. The finite element model of a welded A-type frame was constructed to analyze stress distribution and predict fatigue life, the force time histories of which were acquired from multi-body dynamics simulation. The simulated failure position and fatigue life had a good agreement with the actual results. Then, both structural lifetime and weight were considered as optimization objectives. The thickness of main steel plates and elastic and cyclic material parameters were chosen as uncertain design variables as well as main loads at connection locations. The fifty sample points in the light of Latin hypercube sampling method and its responses calculated by finite element analysis were supposed to build the approximation model based on the Kriging approximation method. After its fitting precision was guaranteed, the non-dominated sorting genetic algorithm II (NSGA-II) was utilized to find the optimal solution. Finally, the fatigue life of a welded A-type frame was increased to 2.40 × 105 cycles and its mass was lessened by 8.2%. The optimized results implied that good fatigue performance of this welded A-type frame needs better welding quality, lower running speed for downhill and turning road surface, and thicker front plates. [ABSTRACT FROM AUTHOR]

The notch stress method（ NSM） is a local fatigue analysis method of welded structure,this method has high accuracy because it focus on the analysis of strain and stress of the fatigue weak area,such as weld toe and weld root. The article collected relevant literature of recent years,so the development history and basic principles of notch stress method had been reviewed; the similarities and differences of nominal stress method,structure stress method,and notch stress method were also summarized. Then latest research progress and development trend of this method were introduced from the following three aspects: the reasonable values of fictitious notch radii; the fatigue class assessment（ FAT） of notch; the slopes of notch fatiguelife curves. In the last but not least,the article showed some welded structures application examples of fatigue analysis with NSM in several industrial areas. Through the comprehensive introduction of notch stress method in this paper,it aims to provide beneficial reference for the domestic welded structure fatigue strength design.

In this paper, the influence of the residual stress on the fatigue performance of a welded structure under multiaxial loading modes is studied. First, the local stress state at weld toe is modified via introduction of the residual stress, and a new fatigue life estimation model considering the effect of the residual stress is established by modifying our recently proposed critical plane method. Second, the basic theory and procedure of the finite element simulation on the calculation of the welding residual stress are presented. Finally, a numerical simulation of an aluminum alloy flange-to-tube welding process is conducted, and the calculated residual stress is verified with X-ray diffraction measurement. Furthermore, the performance of the proposed fatigue life estimation model is verified by the experimental data obtained in the fatigue test under different loading modes. It confirms that the consideration of the residual stress is important, especially under the out-of-phase loading mode. [ABSTRACT FROM AUTHOR]

Abstract: In order to improve the fatigue performance of a welded A-type frame in a heavy off-road mining truck, a novel method was presented to implement lifetime and weight collaborative optimization while considering uncertainties in geometry dimension, material properties, and bearing load. The mechanical and cyclic material parameters were obtained from experimental work to characterize the base metal and the weldment. The finite element model of a welded A-type frame was constructed to analyze stress distribution and predict fatigue life, the force time histories of which were acquired from multi-body dynamics simulation. The simulated failure position and fatigue life had a good agreement with the actual results. Then, both structural lifetime and weight were considered as optimization objectives. The thickness of main steel plates and elastic and cyclic material parameters were chosen as uncertain design variables as well as main loads at connection locations. The fifty sample points in the light of Latin hypercube sampling method and its responses calculated by finite element analysis were supposed to build the approximation model based on the Kriging approximation method. After its fitting precision was guaranteed, the non-dominated sorting genetic algorithm II (NSGA-II) was utilized to find the optimal solution. Finally, the fatigue life of a welded A-type frame was increased to 2.40×105 cycles and its mass was lessened by 8.2%. The optimized results implied that good fatigue performance of this welded A-type frame needs better welding quality, lower running speed for downhill and turning road surface, and thicker front plates.

While predicting the welding distortion for a complex welded structure like the guide blade carrier assembly of power generation turbine, the traditional thermo-mechanical models commonly utilized for geometrically simple welded butt and T joints may not be adequate. For large and complex welded structures,the thermo-mechanical elasto-plastic analysis can be computationally prohibitive. Other than simplistic butt and T joints, the aforementioned distortion prediction technique is not so suitable to provide reliable results when applied to large complex 3-D welded structures. Hence, inherent strain method is proposed here to predict distortion in an outer ringof GBC (Guide Blade Carrier) of a steam turbine. Such welded outer rings of GBC are large welded structures having many welded joints of different weld geometries at several planes. In the present study, inherent strain based technique was utilized for the aforementioned welded structure in elastic finite element analysis for the accurate prediction of 3-D distortion patterns with reduced computational time. The predicted and measured values of 3-D distortions of GBC were observed to be in good agreement with the ones provided from the shop floor, indicating the adequacy of inherent strain based method for the prediction of welding distortion in large and complex welded structures. As part of this investigation, a suitable welding fixture was also designed and welding sequence was modified, which were verified through inherent stain method to aid in minimizing the distortion of welded GBC. [ABSTRACT FROM AUTHOR]

This paper presents an experimental procedure to assess damages of welded beams, the weld being transversal to the longitudinal beam axis. It consists of comparing the natural frequencies in intact and damaged state, calculating the frequency shift due to damage and weigh the shifts against patterns derived a priori. [ABSTRACT FROM AUTHOR]

To simulate welding induced transient thermal stress and deformation of large scale FE models, an accelerated explicit method (ACEXP) and graphical processing units (GPU) parallel computing program of the finite element method (FEM) were developed. In the accelerated explicit method, a two-stage computation scheme is employed. The first computation stage is based on a dynamic explicit method considering the characteristics of the welding mechanical process by controlling both the temperature increment and time scaling parameter. In the second computation stage, a static equilibrium computation scheme is implemented after dynamic thermal loading to obtain a static solution of transient thermal stress and welding deformation. It has been demonstrated that the developed GPU parallel computing program has a good scalability for large-scale models of more than 20 million degrees of freedom. The validity of the accelerated explicit method is verified by comparing the transient thermal stress and deformation with those computed by an implicit FEM. Finally, welding deformation and residual stress in a structure model assembled from nine high-strength steel plates and 26 weld lines were efficiently analyzed by ACEXP and GPU parallel computing within 45 h. The computed welding deformation agreed well with measured results, and a good accuracy was obtained. [ABSTRACT FROM AUTHOR]

An energy-based fatigue damage model was used to estimate the fatigue life of a mining truck welded frame. Experimental work including monotonic and strain-controlled cyclic loading was conducted to characterize the base metal and the weld. A dynamic model was created for the whole truck in the ADAMS software to estimate the force histories applied to the frame in different maneuvers over a simulated road. A Finite element (FE) model was generated for the welded frame and the cyclic loading obtained from the dynamic model was applied to the FE model. The FE model was used to find the stress and strain responses, which were then used to calculate the strain energy and the fatigue life. The fatigue life predictions for the frame agreed well with observations of the truck's in-service failure. [ABSTRACT FROM AUTHOR]

The article presents the materials of calculations of circumferential stresses and radial displacements in the wall of two-layer spherical bottom. Three models of bottoms were considered, where different combinations of materials for manufacture of shell layers are used. The rational layer thicknesses, circumferential stresses and radial displacements were determined, which formed in them in the ranges of elastic deformations at different combinations of materials of shell layers. The determination of circumferential stresses was carried out by calculation method according to the analytical dependences and by the method of computer simulation. The application of material with higher strength properties in manufacture of the outer shell leads to the effective loading of their common wall, reduction in its thickness and, correspondingly, increase in its inner stresses and, eventually, in the rational loading. 10 Ref., 4 Tables, 3 Figures. [ABSTRACT FROM AUTHOR]