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1
Bento, Rodrigo Teixeira, André Ferrus Filho, and Marco Antonio Fumagalli. "Structural Design and Stress Analysis of a High-Speed Turbogenerator Assembly Supported by Hydrodynamic Bearings." International Journal of Manufacturing, Materials, and Mechanical Engineering 10, no. 1 (January 2020): 54–67. http://dx.doi.org/10.4018/ijmmme.2020010104.
Повний текст джерелаАнотація:
Turbine and bushing bearing are the most critical components of high-speed machines. This article describes the design of a high-speed turbine supported by hydrodynamic bearings. The mathematical dimensioning and the FEM analysis are presented to validate the mechanical strength of the turbine and the bushing bearing models. Fatigue life and factor of safety were also determined. The simulations showed that the maximum Von Mises stress values obtained are associated to the centrifugal force generated by the system rotational movement. The results variation was mainly due to the properties of the materials proposed. For the turbine, 7075-T6 aluminum alloy and SAE 4340 steel obtained satisfactory behavior under a constant operating speed of 30,000 RPM. For the hydrodynamic bearing, the TM23 bronze alloy exhibited excellent results, without fracture, and low mechanical deformation. The models exhibited a great potential employment in several applications, such as biogas systems to generate electrical energy, and educational test bench for thermodynamic and tribological simulations.
2
HARLOW, D. GARY. "PARTICLE STATISTICS IN ALUMINUM ALLOYS." International Journal of Reliability, Quality and Safety Engineering 13, no. 04 (August 2006): 379–95. http://dx.doi.org/10.1142/s021853930600232x.
Повний текст джерелаАнотація:
Pitting corrosion and fatigue crack growth are primary degradation mechanisms that affect the durability and integrity of structures made of aluminum alloys, and they are concerns for commercial transport and military aircraft. The heterogeneous nature of aluminum alloys is the reason that these are operative damage mechanisms. Typically, there are about 2,000 constituent particles per mm2on polished surfaces. Corrosion pits commence at the constituent particles and evolve into severe pits by sustained growth through clusters of particles. The severe pits are nucleation sites for subsequent fatigue crack growth. Even when the environment is not as deleterious, fatigue cracks nucleate from clusters of particles. Thus, the role of heterogeneous clusters of constituent particles is critical to the damage evolution of aluminum alloys. To formulate stochastic models that can serve as part of structural reliability analyses for the damage evolution in aluminum alloys, it is essential that quantitative descriptions of the spatial statistics of the particles and particle clusters, including their location, size, and density are developed. The primary purpose of this effort is to estimate statistically the distribution functions of the key geometrical properties of constituent particles in aluminum alloys and their role in damage evolution.
3
Lee, Jungsub, Sang-Youn Park, and Byoung-Ho Choi. "Evaluation of Fatigue Characteristics of Aluminum Alloys and Mechanical Components Using Extreme Value Statistics and C-Specimens." Metals 11, no. 12 (November 27, 2021): 1915. http://dx.doi.org/10.3390/met11121915.
Повний текст джерелаАнотація:
In this study, the fatigue characteristics of aluminum alloys and mechanical components were investigated. To evaluate the effect of forging, fatigue specimens with the same chemical compositions were prepared from billets and forged mechanical components. To evaluate the cleanliness of the aluminum alloys, the cross-sectional area of specimens was observed, and the maximum inclusion sizes were obtained using extreme value statistics. Rotary bending fatigue tests were performed, and the fracture surfaces of the specimens were analyzed. The results show that the forging process not only elevated the fatigue strength but also reduced the scatter of the fatigue life of aluminum alloys. The fatigue characteristics of C-specimens were obtained to develop finite-element method (FEM) models. With the intrinsic fatigue properties and strain–life approach, the FEM analysis results agreed well with the test results.
4
Ma, Shuai, Zhibo Zhang, Zhuming Huang, Dongfu Song, Yiwang Jia, Nan Zhou, Kai Wang, Kaihong Zheng, and Huijing Du. "Prediction of Grain Size in Cast Aluminum Alloys." Crystals 12, no. 4 (March 29, 2022): 474. http://dx.doi.org/10.3390/cryst12040474.
Повний текст джерелаАнотація:
Grain refinement of cast alloys, especially aluminum–silicon and magnesium-based alloys, is an effective approach to improve the strength of alloys. Grain size is the most representative parameter used to characterize grain refinement in the industry, thereby attracting increasing attention for developing accurate grain size prediction models. In this paper, several important grain size prediction models under different adaptation conditions are reviewed. These models are obtained either by regression of experimental data or by physical/mathematical inference under certain assumptions of specified cases, focusing on the effects of alloy composition, solidification temperature gradient, grain growth rate, and fining agent composition, among others. The trends of grain size prediction models were also discussed. The results revealed machine learning as an effective tool to establish a data-driven prediction model of grain size in cast aluminum alloys.
5
Golod, V. M., and L. Yu Dobosh. "DIAGNOSTICS OF DENDRITE STRUCTURE OF MULTICOMPONENT ALUMINUM ALLOYS." Litiyo i Metallurgiya (FOUNDRY PRODUCTION AND METALLURGY), no. 1 (April 6, 2018): 55–62. http://dx.doi.org/10.21122/1683-6065-2018-1-55-62.
Повний текст джерелаАнотація:
Stages of system analysis and mathematical models for predicting the dendritic structure of multicomponent aluminum alloys are considered. Computer diagnostics of nonequilibrium crystallization is realized by the joint use of the apparatus of computational thermodynamics and means of computational heat transfer for solving problems of computational materials science. The results of modeling the evolution of the dendritic structure are presented with a change in the diffusion intensity in the solid phase from equilibrium conditions to complete suppression.
6
Kang, Hong-Tae, and Sai Boorgu. "Fatigue Life Prediction of Self-Piercing Rivet Joints Between Magnesium and Aluminum Alloys." MATEC Web of Conferences 165 (2018): 10004. http://dx.doi.org/10.1051/matecconf/201816510004.
Повний текст джерелаАнотація:
Various light materials including aluminum alloys and magnesium alloys are being used to reduce the weight of vehicle structures. Joining of dissimilar materials is always a challenging task to construct a solid structure. Self-piercing rivet (SPR) joint is one of various joining methods for dissimilar materials. Front shock tower structures were constructed with magnesium alloy (AM60) joined to aluminum alloy (Al6082) by SPR joints. To evaluate the durability performance of the SPR joints in the structures, fatigue tests of the front shock tower structures were conducted with constant amplitude loadings. Furthermore, this study investigated fatigue life prediction method of SPR joints and compared the fatigue life prediction results with that of experimental results. For fatigue life prediction of the SPR joints in the front shock tower structures, lap-shear and cross-tension specimens of SPR joint were constructed and tested to characterize the fatigue properties of the SPR joint. Then, the SPR joint was represented with area contact method (ACM) in finite element (FE) models. The load-life curves of the lap-shear and cross-tension specimens were converted to a structural stress-life (S-N) curve of the SPR joints. The S-N curve was used to predict fatigue life of SPR joints in the front shock tower structures. The test results and the prediction results were well correlated.
7
Zakharchenko, Kirill, Vladimir Kapustin, Alexey Larichkin, and Yaroslav Lukyanov. "Influence of Technology of Hot Forming of Plates from Aluminum Alloys Al-Cu-Li-Zn and Al-Zn-Mg-Cu on Resistance to Fatigue Fracture." Metal Working and Material Science 22, no. 4 (December 8, 2020): 94–109. http://dx.doi.org/10.17212/1994-6309-2020-22.4-94-109.
Повний текст джерелаАнотація:
Introduction. One of the primary objectives in the development of promising aircraft products is to reduce the weight of the aircraft structure. This problem can be solved by applying new low density materials such as aluminum alloys alloyed with lithium (for example, Al-Cu-Li-Zn) in the design of parts. The use of these materials in aircraft construction is limited by the processing technology, which must be such as not to damage the material and not reduce its strength properties. Such technologies include processing by pressure with heating, when creep processes are activated and the material passes into a state close to superplasticity. The purpose of the work: assessment of the effect of pressure shaping of aluminum alloys Al-Cu-Li-Zn and Al-Zn-Mg-Cu in creep mode on strength. The paper investigates the influence of the technology of pressure shaping of aluminum alloys Al-Cu-Li-Zn and Al-Zn-Mg-Cu on the resistance to fatigue failure. The work uses a method that allows to determine the ultimate stresses using diagrams of the accumulation of irreversible deformations; method of forming thick plates (40 mm) in the creep mode. The previously selected optimum temperatures for forming the plates are used. A non-contact coordinate measuring system is used to perform surface inspection after shaping. Fractography of the fracture of samples of alloy Al-Cu-Li-Zn and Al-Zn-Mg-Cu after fatigue failure is performed. Mathematical modeling of the deformation process of plates in creep mode is carried out in the MSC.Marc package. As a result, a conservative evaluation of the endurance limit for aluminum alloys Al-Cu-Li-Zn and Al-Zn-Mg-Cu is obtained. The shaping of thick plates in the creep mode is carried out. More than 80% of the board surface is formed with a deviation of less than 1 mm from the target size. Fatigue tests of samples made of molded panels of alloys Al-Cu-Li-Zn and Al-Zn-Mg-Cu are carried out, fatigue curves are plotted. The fractography of the surface of the fatigue fracture showed the presence of oxides in the samples of alloy Al-Cu-Li-Zn, in contrast to alloy Al-Zn-Mg-Cu. The results of fatigue tests are discussed, showing that the characteristics of the technological process of shaping and heat treatment do not deteriorate the fatigue properties of the investigated alloys. Comparative tests show that alloy Al-Cu-Li-Zn has higher fatigue characteristics. Mathematical modeling show that the use of the Boyle-Norton steady-state creep law is not enough to describe the process of plate forming. The necessity of setting the inverse problem of creep age forming is noted, where the coordinates of the punches of the loading device should act as boundary conditions.
8
Zahran, B. "Using Neural Networks to Predict the Hardness of Aluminum Alloys." Engineering, Technology & Applied Science Research 5, no. 1 (February 8, 2015): 757–59. http://dx.doi.org/10.48084/etasr.529.
Повний текст джерелаАнотація:
Aluminum alloys have gained significant industrial importance being involved in many of the light and heavy industries and especially in aerospace engineering. The mechanical properties of aluminum alloys are defined by a number of principal microstructural features. Conventional mathematical models of these properties are sometimes very complex to be analytically calculated. In this paper, a neural network model is used to predict the correlations between the hardness of aluminum alloys in relation to certain alloying elements. A backpropagation neural network is trained using a thorough dataset. The impact of certain elements is documented and an optimum structure is proposed
9
Chausov, Mykola, Andrii Pylypenko, Pavlo Maruschak, and Abdellah Menou. "Phenomenological Models and Peculiarities of Evaluating Fatigue Life of Aluminum Alloys Subjected to Dynamic Non-Equilibrium Processes." Metals 11, no. 10 (October 13, 2021): 1625. http://dx.doi.org/10.3390/met11101625.
Повний текст джерелаАнотація:
Physical-mechanical models for predicting the fatigue life of aluminum alloys D16ChATW and 2024-T351 are proposed and tested. Damage accumulation patterns are established for these alloys in the initial state and after dynamic non-equilibrium processes (DNP) of different intensity that occur at maximum cycle stresses σmax from 340 to 440 MPa, cycle asymmetry coefficients R = 0.1 and load frequency f = 110 Hz. The main model parameters are the initial alloy hardness HV and the limiting parameters of scatter of hardness values m. These parameters are evaluated in the process of cyclic loading with fixed maximum stresses of the cycles. Relative values me are also considered. For the alloys in the initial state, the proposed models are shown to be in good agreement with the experimental results. Conversely, structural changes taking place in alloys after DNP complicate the prediction of their fatigue life.
10
DebRoy, T., A. De, H. K. D. H. Bhadeshia, V. D. Manvatkar, and A. Arora. "Tool durability maps for friction stir welding of an aluminium alloy." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 468, no. 2147 (July 25, 2012): 3552–70. http://dx.doi.org/10.1098/rspa.2012.0270.
Повний текст джерелаАнотація:
Friction stir welding is not used for hard alloys because of premature tool failure. A scheme is created that exploits the physical three-dimensional heat and mass flow models, and implements them into a fast calculation algorithm, which, when combined with damage accumulation models, enables the plotting of tool durability maps that define the domains of satisfactory tool life. It is shown that fatigue is an unlikely mechanism for tool failure, particularly for the welding of thin plates. Plate thickness, welding speed, tool rotational speed, shoulder, and pin diameters and pin length all affect the stresses and temperatures experienced by the tool. The large number of these variables makes the experimental determination of their effects on stresses and temperatures intractable and the use of a well-tested, efficient friction stir welding model a realistic undertaking. An artificial neural network that is trained and tested with results from a phenomenological model is used to generate tool durability maps that show the ratio of the shear strength of the tool material to the maximum shear stress on the tool pin for various combinations of welding variables. These maps show how the thicker plates and faster welding speeds adversely affect tool durability and how that can be optimized.
11
Rusnak, Cameron R., and Craig C. Menzemer. "Fatigue Behavior of Nonreinforced Hand-Holes in Aluminum Light Poles." Metals 11, no. 8 (July 30, 2021): 1222. http://dx.doi.org/10.3390/met11081222.
Повний текст джерелаАнотація:
Hand-holes are present within the body of welded aluminum light poles. They are used to provide access to the electrical wiring for both installation and maintenance purposes. Wind is the main loading on these slender aluminum light poles and acts in a very cyclic way. In the field, localized fatigue cracking has been observed. This includes areas around hand-holes, most of which are reinforced with a cast insert welded to the pole. This study is focused on an alternative design, specifically hand-holes without reinforcement. Nine poles with 18 openings were fatigue tested in four-point bending at various stress ranges. Among the 18 hand-holes tested, 17 failed in one way or another as a result of fatigue cracking. Typically, fatigue cracking would occur at either the 3:00 or 9:00 positions around the hand-hole and then proceed to propagate transversely into the pole before failure. Finite element analysis was used to complement the experimental study. Models were created with varying aspect ratios to see if the hand-hole geometry had an effect on fatigue life.
12
Golestaneh, Amirreza Fahim, Aidy Ali, and Mehdi Bayat. "Analytical and Numerical Investigation of Fatigue Crack Growth in Aluminum Alloy." Key Engineering Materials 462-463 (January 2011): 1050–55. http://dx.doi.org/10.4028/www.scientific.net/kem.462-463.1050.
Повний текст джерелаАнотація:
The work presents a summary of previous studies on fatigue crack propagation within various Aluminum alloys. The effective characteristics on crack growth are first highlighted and the influence of surface engineering such as polishing, shot peening and skimming to enhance the failure resistance are discussed. Several different existing developed models for predicting the rate of crack propagation are compared in terms of incorporated effective parameters. Finally numerical and computational analyses as the accurate, fast and cheap methods which have attracted the Engineers’ interest are reviewed and compared with other methods.
13
Al-Hadrayi, Ziadoon M. R., Ahmed Naif Al-Khazraji, and Ahmed Adnan Shandookh. "Investigation of Fatigue Behavior for Al/Zn Functionally Graded Material." Materials Science Forum 1079 (December 26, 2022): 49–56. http://dx.doi.org/10.4028/p-8umjsp.
Повний текст джерелаАнотація:
This paper presented an experimental and numerical study of functionally graded materials made by the permanent casting method and in three models with different mixing ratios between aluminum and zinc alloys (FGM1, FGM2, and FGM3) as in figure 1. In the permanent casting process, three models of the functionally graded material were produced and mechanical tests were conducted on them such as tensile and hardness tests, and the behavior of tensile strength, yield strength, elastic modulus, and fatigue was analyzed on them. The fatigue test was conducted at six levels of load and at room temperature. Simulations were carried out for the three models and a simulated fatigue test for the functionally graded material into the Ansys program. The results of the fatigue test showed an apparent effect of the different mixing ratios of the functional-grade material. As well as the numerical results were, close to the experimental results. There was an improvement in the fatigue life compared to FGM3, by 23% to FGM2. In addition, the fatigue life of the FGM3 of 11% higher than from the FGM1 model. In addition to that, which is important, the improvement in the fatigue life characteristics of the third type was 36% compared to the alloys from which the functionally graded materials were made.
14
SILACHAI, Anuak, and Suriya PRASOMTHONG. "Optimized parameter of dissimilar joining between Al6061-T6 and height-strength steel with friction stir spot welding process (FSSW)." Journal of Metals, Materials and Minerals 32, no. 4 (December 26, 2022): 118–27. http://dx.doi.org/10.55713/jmmm.v32i4.1538.
Повний текст джерелаАнотація:
High-strength steel and aluminum alloys are used to manufacture modern vehicles. The objective was to reduce the weight and fuel consumption of the vehicles. In this study the optimum parameters for the friction stir spot welding (FSSW) process between Al6061-T6 aluminum alloy and HSS590 high-strength steel were determined. Response surface methodology based on central composite design (CCD) with three parameters, five levels, and 19 runs was used to conduct experiments and develop mathematical regression models. The three joint parameters were tool speed, welding feed, and dwell time. Analysis of variance was then performed to examine the adequacy of the developed models. Finally, the effects of the process parameters on the mechanical properties were investigated using mathematical models. In addition, the distribution of the chemical composition and fracture characteristics of the joints was examined using scanning electron microscopy (SEM). The investigation found that the optimum welding parameters were a tool speed of 1576 rpm, welding feed rate of 45 mm∙min-1, and dwell time of 10 s. Furthermore, the results confirmed that the mathematical models and experiments were consistent.
15
Zafar, Muhammad Hamza, Hassaan Bin Younis, Majad Mansoor, Syed Kumayl Raza Moosavi, Noman Mujeeb Khan, and Naureen Akhtar. "Training Deep Neural Networks with Novel Metaheuristic Algorithms for Fatigue Crack Growth Prediction in Aluminum Aircraft Alloys." Materials 15, no. 18 (September 6, 2022): 6198. http://dx.doi.org/10.3390/ma15186198.
Повний текст джерелаАнотація:
Fatigue cracks are a major defect in metal alloys, and specifically, their study poses defect evaluation challenges in aluminum aircraft alloys. Existing inline inspection tools exhibit measurement uncertainties. The physical-based methods for crack growth prediction utilize stress analysis models and the crack growth model governed by Paris’ law. These models, when utilized for long-term crack growth prediction, yield sub-optimum solutions and pose several technical limitations to the prediction problems. The metaheuristic optimization algorithms in this study have been conducted in accordance with neural networks to accurately forecast the crack growth rates in aluminum alloys. Through experimental data, the performance of the hybrid metaheuristic optimization–neural networks has been tested. A dynamic Levy flight function has been incorporated with a chimp optimization algorithm to accurately train the deep neural network. The performance of the proposed predictive model has been tested using 7055 T7511 and 6013 T651 alloys against four competing techniques. Results show the proposed predictive model achieves lower correlation error, least relative error, mean absolute error, and root mean square error values while shortening the run time by 11.28%. It is evident through experimental study and statistical analysis that the crack length and growth rates are predicted with high fidelity and very high resolution.
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Ahmed, Mohamed M. Z., Mohamed I. A. Habba, Nabil Jouini, Bandar Alzahrani, Mohamed M. El-Sayed Seleman, and Ahmed El-Nikhaily. "Bobbin Tool Friction Stir Welding of Aluminum Using Different Tool Pin Geometries: Mathematical Models for the Heat Generation." Metals 11, no. 3 (March 7, 2021): 438. http://dx.doi.org/10.3390/met11030438.
Повний текст джерелаАнотація:
In this work, three mathematical models for the heat generation during bobbin tool friction stir welding (BT-FSW) of aluminum using three tool pin geometries have been proposed. The models have utilized and updated the available models for the heat generation during the conventional tool friction stir welding (CT-FSW). For the validation of the models, BT-FSW experiments have been carried out for aluminum alloy AA1050 using three different pin geometries (cylindrical, square, and triangular), at different welding speeds of 200, 400, 600, 800, and 1000 mm/min and a constant tool rotation speed of 600 rpm. The welding temperatures during BT-FSW have been measured to be compared with that calculated from the models at the same parameters. It has been found that the calculated welding temperatures from the models and that measured during BT-FSW are in good agreement at all the investigated welding speeds especially in case of the square and cylindrical pins, proving the validity of the developed models for the predication of the heat generation as well as the welding temperatures. This will allow proper designing of the BT-FSW parameters and avoiding the conditions that can deteriorate the joint quality and properties.
17
Luo, Ji Xiang, and Chun Tang. "Fretting Fatigue Behavior of Riveted Al 6XXX Components." Applied Mechanics and Materials 34-35 (October 2010): 1388–92. http://dx.doi.org/10.4028/www.scientific.net/amm.34-35.1388.
Повний текст джерелаАнотація:
The riveting is widely used for fitting together two or more elements of structure in the same or different materials. In these assemblies the stress field is complex, we have to consider the effect of the geometrical discontinuity, the contact, the tightening, the material properties and the applied load. The current work focus on the study of fretting fatigue crack formation in common 6XXX aluminum alloys, used in land transportation equipments, and uncovering characteristic origins of crack by experimental and numerical methods based on multi-axial fatigue life models. 3D finite element models were validated by the experimental results obtained with strain gauges. The influences of the contact friction coefficient at the fretting surface, the fastening forces and the remote stress applied in the fretting fatigue experiments on the crack origins are discussed by the comparison of the different numerical results.
18
Nourian-Avval, Ahmad, and Ali Fatemi. "Characterization and Analysis of Porosities in High Pressure Die Cast Aluminum by Using Metallography, X-Ray Radiography, and Micro-Computed Tomography." Materials 13, no. 14 (July 9, 2020): 3068. http://dx.doi.org/10.3390/ma13143068.
Повний текст джерелаАнотація:
Mechanical performance of cast aluminum alloys is strongly affected by the defects formed during solidification. For example, fractography studies of the fatigue specimens have shown that fatigue failure in aluminum castings containing defects is almost always initiated from defects, among which pores are most detrimental. However, elimination of these pores is neither always economically nor technically possible. This work characterizes defects in high pressure die cast aluminum alloy as an illustrative material, but the methods used can be applicable to other types of castings and defects. The defects were evaluated using metallography as well as micro-computed tomography techniques. The variability of defects between the specimens of two sizes as well as different porosity levels are studied statistically. The distributions of defects based on location within the specimens are also analyzed. Moreover, the maximum defect size within the specimens are estimated using extreme value statistics, which can be used as an input to fatigue life prediction models. Extreme value statistics is applied on both 2D and 3D defect data. The accuracy of each approach is verified by comparing the estimated maximum defect size within the specimens with the maximum observed defects on fracture surfaces of fatigue specimens.
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Neerukatti, Rajesh Kumar, Aditi Chattopadhyay, Nagaraja Iyyer, and Nam Phan. "A hybrid prognosis model for predicting fatigue crack propagation under biaxial in-phase and out-of-phase loading." Structural Health Monitoring 17, no. 4 (August 15, 2017): 888–901. http://dx.doi.org/10.1177/1475921717725019.
Повний текст джерелаАнотація:
A hybrid prognosis model has been developed to predict the crack propagation in aluminum alloys subject to biaxial in-phase and out-of-phase fatigue loading conditions. The novel methodology combines physics-based modeling with machine learning techniques to predict crack growth in aluminum alloys. Understanding the failure mechanisms under these complex loading conditions is critical to developing reliable prognostic models. Therefore, extensive fatigue tests were conducted to study the failure modes of carefully designed cruciform specimens. Energy release rate was used as the physics-based parameter and Gaussian process was used to model the complex nonlinear relationships in the prognosis framework. The methodology was used to predict crack propagation in Al7075-T651 under a range of loading conditions. The predictions from the prognosis model were validated using the data obtained from the biaxial tests. The results indicate that the algorithm is able to accurately predict the crack propagation under proportional, non-proportional, in-phase, and out-of-phase loading conditions.
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Arifeen, S., G. Potirniche, A. Elshabini, and F. Barlow. "Modeling of Failure in Aluminum Alloy Braze for a High Temperature Thermoelectric Assembly." International Symposium on Microelectronics 2013, no. 1 (January 1, 2013): 000957–63. http://dx.doi.org/10.4071/isom-2013-thp63.
Повний текст джерелаАнотація:
The objective of this work is to design a commercially viable thermoelectric generator (TEG) assembly that can be used in passenger vehicles to be able to withstand extreme environmental conditions. Since the operating temperatures of the TEGs can reach temperature levels higher than 500 °C, aluminum braze alloys offer a good high temperature solution for die attach. However, the evolution of fatigue damage in the aluminum braze must be understood in order to ensure an acceptable reliability of the TEG. In this paper, the proposed design of TEG package assembly was evaluated under extreme temperature conditions. Three-dimensional models of full scale TEG were analyzed using finite element analysis (FEA). The failures of aluminum alloy based braze (high temperature form of solder) material in the TEG application was investigated. Low cycle fatigue using direct cyclic approach was considered for the reliability analysis. Continuum damage mechanics approach was used to study the fatigue failure due to power cycling. Different TEG assembly designs were investigated and compared to determine the best possible solution for the extreme environment application.
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da Silva Gonçalves, Roberto, and Carlos E. Chaves. "Fatigue Life Estimation of Aeronautical Joints Based on Stress Severity Factor." Advanced Materials Research 1135 (January 2016): 128–39. http://dx.doi.org/10.4028/www.scientific.net/amr.1135.128.
Повний текст джерелаАнотація:
The goal of the present work is to investigate the validity limits and safe application range of Stress Severity Factor methodology in estimating fatigue life of aircraft fuselage joints. Fatigue tests were conducted and recorded data from aluminum alloys joints was subjected to analytical evaluation. FE models were created to obtain fasteners load distribution and determine normal stress due to secondary bending. Severity Factor method conservatively estimated fatigue life of 74% for the analyzed joints. Its robustness was verified for lap joints fatigue life estimative, but for almost all single strap joints, secondary bending effect were significant. Thus for this kind of joints, a term accounting for bending stress was added to the original severity factor formulation to increase level of safety in fatigue life estimates.
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Kecsmar, J., and R. A. Shenoi. "Some Notes on the Influence of Manufacturing on the Fatigue Life of Welded Aluminum Marine Structures." Journal of Ship Production 20, no. 03 (August 1, 2004): 164–75. http://dx.doi.org/10.5957/jsp.2004.20.3.164.
Повний текст джерелаАнотація:
Designers are constantly looking for ways to reduce the structure weight to lower the overall displacement and hence the cost of fast ferries and other high-speed vessels. The easiest option for the designer is to choose a lightweight material. Aluminum has become the adopted choice of material for high-speed vessels owing to its high strength to weight characteristics. Unlike steel, aluminum is more prone to fatigue cracking and has no fatigue limit. In order to minimize weight, the designer will make use of finite element methods to optimize the scantlings and perform fatigue checks against established codes. This can lead to a structure that has the empirical margins of safety reduced owing to the accuracy of mathematical modeling. However, what is often overlooked is the effect the manufacturing process has on the fatigue life of the fabricated structure. This aspect is excluded from the designer's fatigue calculations, which assist in reducing the scantlings. Currently, there is no guidance for fatigue life reduction for the designer that establishes good and bad workshop practice, other than experience, or the implications of basic shipyard fabrication. It is shown that whereas strain-hardened alloys improve mechanical strength, they reduce ductility. This has consequences when forming the hull plate by potentially introducing crack like flaws into the alloy matrix if the plater overrolls the plate. If there is misalignment or there is too much gap between the plates, the weld will create localized stress concentrations. If the welder has poor joint preparation or gas shielding, porosity can be introduced into the weld. Porosity has a significant effect on the fatigue life of the weldment. This paper brings together a collection of data on such issues that the designer needs to be aware of to prevent an unwanted fatigue failure in the fabrication process.
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Rutecka, A., L. Dietrich, and Zbigniew L. Kowalewski. "Evaluation of the Heat Treatment Role for Light Aluminum Alloys Subjected to Creep and Low Cycle Fatigue." Materials Science Forum 638-642 (January 2010): 455–60. http://dx.doi.org/10.4028/www.scientific.net/msf.638-642.455.
Повний текст джерелаАнотація:
The AlSi8Cu3 and AlSi7MgCu0.5 cast aluminium alloys of different composition and heat treatment were investigated to verify their applicability as cylinder heads in the car engines [1]. Creep tests under the step-increased stresses at different temperatures, and low cycle fatigue (LCF) tests for a range of strain amplitudes and temperatures were carried out. The results exhibit a significant influence of the heat treatment on the mechanical properties of the AlSi8Cu3 and AlSi7MgCu0.5. An interesting fact is that the properties strongly depend on the type of quenching. Lower creep resistance (higher strain rates) and lower stress response during fatigue tests were observed for the air quenched materials in comparison to those in the water quenched. Cyclic hardening/softening were also observed during the LCF tests due to the heat treatment applied. The mechanical properties determined during the tests can be used to identify new constitutive equations and to verify existing numerical models.
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Dai, Yi Chun, De Shuang Zou, Lun Fu Tian, Ye Qing Shen, and Jin Fang Yang. "Evaluation of the Uncertainty of Determination Zinc in Cast Aluminum Alloy Ingots by Photoelectric Direct Reading Spectrometry." Applied Mechanics and Materials 427-429 (September 2013): 1301–5. http://dx.doi.org/10.4028/www.scientific.net/amm.427-429.1301.
Повний текст джерелаАнотація:
According to JJF 1059.1-2012 of Evaluation and Expression of Uncertainty, the uncertainty of determination zinc in cast aluminum alloys ingots samples by photoelectric direct reading spectrometry was evaluated. The uncertainty sources were analyzed and the relevant mathematical models were established. The influential factors of precision were dissected. Each of the standard uncertainty, the combined standard uncertainty, the expanded uncertainty and the confidence interval were anatomized.
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Abd Elnabi, Mohamed Mohamed, Tarek Abd Elsadek Osman, Alaa Eldeen El Mokadem, and Abou Bakr Elshalakany . "Modeling and Optimization of Friction Stir Welding Parameters for Joining Dissimilar Aluminum Alloys." Advanced Journal of Graduate Research 4, no. 1 (April 4, 2018): 1–14. http://dx.doi.org/10.21467/ajgr.4.1.1-14.
Повний текст джерелаАнотація:
The objectives of this work are to optimize the process parameters on the mechanical properties (ultimate tensile strength (UTS) and ductility) of dissimilar joints between AA5454 and AA7075 produced by friction stir welding and to determine which of them is significant by using Taguchi L16 optimization method. Seven parameters at two levels were selected in this study. The selected parameters are tool rotational speed, traverse speed, pin profile (based on taper angle), D/d ratio, tool tilt angle, plunge depth, and base metal location. Then, mathematical models are built as function of significant parameters/ interactions using Response Surface Methodology. The results of this work showed that the rotational speed, traverse speed, D/d ratio and plunge depth are significant parameters in determining UTS (Mean, Signal to noise ratio (S/N)) at different confidence levels, but pin profile, location of base metal and tool tilt angle are insignificant parameters at any confidence levels. The traverse speed has the highest contribution to the process for UTS about 18.577 % and 16.943 % for S/N ratio and mean, respectively. The accuracy of the models according to the UTS is 97.678 % and 99.56 %for mean and S/N ratio, respectively. The maximum joint efficiency, compared to the strength of the AA5454, is 85.3%.
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Konda, Nithin, Raviraj Verma, and Rengaswamy Jayaganthan. "Machine Learning Based Predictions of Fatigue Crack Growth Rate of Additively Manufactured Ti6Al4V." Metals 12, no. 1 (December 27, 2021): 50. http://dx.doi.org/10.3390/met12010050.
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The present work focusses on machine learning assisted predictions of the fatigue crack growth rate (FCGR) of Ti6Al4V (Ti64) processed through laser powder bed fusion (L-PBF) and post processing. Various machine learning techniques have provided a flexible approach for explaining the complex mathematical interrelationship among processing-structure-property of the materials. In the present work, four machine learning (ML) algorithms, such as K- Nearest Neighbor (KNN), Decision Trees (DT), Random Forests (RF), and Extreme Gradient Boosting (XGB) algorithms are implemented to analyze the Fatigue Crack growth rate (FCGR) of Ti64 alloy. After tuning the hyper parameters for these algorithms, the trained models were found to estimate the unseen data as equally well as the trained data. The four tested ML models are compared with each other over the training as well as testing phase, based on their mean squared error and R2 scores. Extreme Gradient Boosting has performed better for the FCGR predictions providing least mean squared errors and higher R2 scores compared to other models.
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Ahmed, Naveed, Madiha Rafaqat, Kashif Ishfaq, Ateekh Ur Rehman, Adeel Hassan, Usama Umer, Adham Ezzat Ragab, and Ayoub Al-Zabidi. "Comparison of Laser Milling Performance against Difficult-To-Cut Alloys: Parametric Significance, Modeling and Optimization for Targeted Material Removal." Materials 12, no. 10 (May 23, 2019): 1674. http://dx.doi.org/10.3390/ma12101674.
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During laser milling, the objective is not always to maximize the material removal rate (MRR). Milling of new material with targeted MRR is challenging without prior knowledge and established sets of laser parameters. The laser milling performance has been evaluated for three important aerospace alloys, i.e., titanium alloy, nickel alloy and aluminum alloy using the response surface method experimental plan (54 experiments for each alloy). Parametric effects of five important laser parameters, statistical analysis (main effects, interaction effects, strength and direction of effects), mathematical modeling and optimality search is conducted for the said alloys. Under the non-optimized laser parameters, the actual MRR significantly varies from the targeted MRR. Variation in the aluminum alloy is at the top as compared to the other two alloys. Among other significant terms, three terms have the largest effect on MRR in the case of TiA, two terms in the case of NiA, and five terms in the case of AlA. Under the optimized sets of laser parameters, the actual material removal highly close to the desired level (100%) can be achieved with minimum variation in all the three alloys. Mathematical models proposed here have the capability to well predict material removal prior to the actual machining of Ti6Al4V, Inconel 718 and AA 2024.
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Crawford, Bruce R., Chris Loader, Qian Chu Liu, Timothy J. Harrison, P. Khan Sharp, and Gunnar Härkegård. "Experimental and Modeling Study of the Effect of Corrosion Pitting on Fatigue Failure Locations in Aircraft Components." Advanced Materials Research 891-892 (March 2014): 236–41. http://dx.doi.org/10.4028/www.scientific.net/amr.891-892.236.
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It is well established that corrosion pits reduce the fatigue life and structural integrity of aluminum alloy aircraft components. A great deal of research has been conducted in this area in the last 20 years. This problem is not unique to aluminum alloys or aircraft however. Similar problems have been observed in the steel components of other engineered structures such as steel pipelines and steam turbine blades. However the effect of pitting corrosion on the probable location of fatigue failures has been overlooked. This is problematic as corrosion pits have caused fatigue failures in locations and components where they were unexpected, such as the trailing edge flap lug of the F/A 18 fighter aircraft. DSTO have called this problem ‘Corrosion Criticality’. This paper reports the development of Monte-Carlo models of how pitting corrosion affects the location of fatigue failures in two fatigue specimen geometries that have different stress concentration factors (kt). These specimens are a low-kt fatigue life specimen and a high-kt fatigue life specimen with three holes arranged along its centerline. The modeling results for the low-kt specimen are then compared with experimental results for that specimen. The low-kt model produces good estimates of fatigue life and of the probability of fatigue failure at any given location in the specimen’s gauge section. The process that will be followed to develop the high-kt model is outlined. The paper includes a discussion of using the Corrosion Criticality models to reduce the cost of corrosion maintenance by (i) identifying areas in which corrosion inspections are critical and (ii) identify aircraft components for which pitting corrosion will not be a threat to airworthiness during the life of an aircraft.
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Liu, Binchao, Rui Bao, Yamei Niu, Songsong Lu, and Kai Wang. "Peridynamic Simulation of Fatigue Crack Growth Behaviour with the Effect of Microstructure." MATEC Web of Conferences 165 (2018): 04003. http://dx.doi.org/10.1051/matecconf/201816504003.
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The purpose of this paper is to explore the influences of microstructures on crack growth behaviour in 2324-T39 aluminum alloy based on peridynamic(PD) theory. The microelastic bond-based peridynamic constitutive is modified as microplastic to describe the plasticity of aluminum alloys. A new method to establish polycrystalline models based on metallographs is adopted, and grains are reflected in simulations by setting transgranular and intergranular pairwise force in the corresponding bonds. Two kinds of microstructures are modeled according to metallographs, and a special kind of crack branch resulted from the link-up of the secondary crack with the main crack and the growth of the branched crack is successfully captured. The PD simulations reveal that microstructure orientation characteristics have an impact on crack propagation paths and crack growth modes, and it is easier for the secondary-crack resulted macroscopic crack branching to appear if grain boundaries locate not too close to the leading crack tip but within the crack tip plastic zone. The numerical results are verified by experiments and fractographic analysis.
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Karash, E. T., H. M. Ali, and A. F. Hamid. "Mathematical Model for the Temperature Distribution on The Surface of Two Aluminum Alloys Welded by Friction Stir Welding." Annals of Dunarea de Jos University of Galati. Fascicle XII, Welding Equipment and Technology 33 (December 15, 2022): 47–58. http://dx.doi.org/10.35219/awet.2022.04.
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The aim of this study was to predict the temperatures on all surfaces of three-dimensional models using the ANSYS 15.0 program. Firstly, the temperatures from the welding centre to the edges of the models of two aluminium alloys (AA-7075 & AA-2024) welded by friction stir welding process were perceived. Secondly, the distribution of temperatures from the start of the welding process to its end and the derivation of equations to predict the distribution of temperatures with the time spent in the welding process, along with the distribution of temperatures with the distance from the centre of the welding process were observed at different travel speeds of the welding cart (TS = 20, 40, 60, 100 mm/sec) and different speeds of the welding tool (TRS=900, 1050, 1200 rpm). The results indicate that the temperature increases with the increase in the rotational speed of the welding tool, while the temperature decreases with the increase in the travel speed of the welding cart. Another result is that the temperature distribution is not symmetrical. The highest values are in the welding centre and decrease significantly as the welding centre is moved away, and the highest temperatures can be reached between (75 – 80%) in the welding centre from the melting point of the two aluminium alloys welded together. It was also found that the temperatures increase significantly twenty seconds after the beginning of the welding process and, afterwards, the increase is small, and three equations were derived to predict the temperature distribution.
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Zakharchenko, Kirill, Vladimir Kapustin, and Alexey Larichkin. "Enhanced assessment of technological factors for Ti-6Al-4V and Al-Cu-Mg strength properties." Metal Working and Material Science 23, no. 4 (December 13, 2021): 125–39. http://dx.doi.org/10.17212/1994-6309-2021-23.4-125-139.
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Introduction. The strength of construction materials when used under cyclic loads is of great importance in design engineering. A significant number of factors that affect the fatigue resistance have predetermined the creation of numerous methods that consider such influence. Nondestructive methods that are based on the connection of the physical degradation of material with strain properties enable evaluating experimentally the fatigue properties of materials. Purpose of study: the analysis of the processes of energy dissipation and strain accumulation during the inelastic cyclic strain of samples, using the VT6 (Ti-6Al-4V) titanium alloy and the D16 (Al-Cu-Mg) aluminum alloy before and after the technological impact. The work experimentally investigates the physical processes of degradation of the VT6 and D16 alloy samples that accompany the process of fatigue failure in materials with homogeneous and inhomogeneous stress-strain states in the concentrator (in the form of a hole and a weld). Typical modes are used to reach the fatigue testing that determine the critical stress in a material sample – the stress at which physical properties (temperature, strain) change without reaching the fatigue failure of samples. Critical stress amplitudes in the cycle, based on the data obtained during the experiment and the results of mathematical simulation, are compared. The effect of stress concentrators on critical loads that a detail can withstand after a unit operation is estimated by the finite-element method (FEM). As a result, the effect of the operational and technological factors on critical stress determined by strain and temperature is estimated. Comparative tests of the VT6 and D16 alloy samples with and without stress concentrators showed that the amplitudes of critical stress decrease by more than 30% in comparison with the ones that are without stress concentrators. The low-cycle fatigue tests of the D16 alloy samples are carried out. Mathematical simulation of the cyclic strain of the samples is carried out using MSC.Marc package. The results of the cyclic loading tests, which show that the characteristics of the technological process reduce the amplitudes of the critical stress of the VT6 and D16 alloys and affect the fatigue properties of the D16 aluminum alloy, are discussed. Mathematical simulation corresponded positively to the experimental data. Such correspondence indicates the possibility of conducting qualitative numerical assessments of the beginning of the inelastic strain accumulation process in structures with stress concentrators under the cyclic stress and the increasing stress amplitude, using the typical sample made of hardening elastoplastic material.
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Kang, Jidong, W. Steven Johnson, and David A. Clark. "Three-Dimensional Finite Element Analysis of the Cold Expansion of Fastener Holes in Two Aluminum Alloys." Journal of Engineering Materials and Technology 124, no. 2 (March 26, 2002): 140–45. http://dx.doi.org/10.1115/1.1448922.
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A three-dimensional finite element analysis is developed for the cold expansion process in two aluminum alloys, 2024-T351 and 7050-T7451. The entire cold working process including hole expansion, elastic recovery, and finish reaming is simulated. Both isotropic hardening and kinematic hardening models are considered in the numerical calculations. The results suggest that a three-dimensional nature exists in the residual stress fields surrounding the hole. There are significant differences in residual stresses at different sections through the thickness. However, residual stress at the surface is shown to remain the same for the different plastic hardening models after the hole has recovered and finish reaming has been performed. The reaming of the material around the hole has slight effect on the maximum value and distribution of residual stresses. A comparison has been drawn between the FEA of average through thickness strain and a previous experimental investigation of strain that utilized neutron diffraction and modified Sachs boring on a 7050 aluminum specimen containing a cold expanded hole. The different methods show very good agreement in the magnitude of strain as well as the general trend. The conclusions obtained here are beneficial to the understanding of the phenomenon of fatigue crack initiation and growth at the perimeter of cold worked holes.
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Savkin, A. N., R. Sunder, A. V. Andronik, and A. A. Sedov. "Effect of Overload on the Near-Threshold Fatigue Crack Growth Rate in a 2024-T3 Aluminum Alloy: III. Analysis of the Efficiency of the Fatigue Crack Growth Models Used to Predict the Fatigue Life under Alternating Loading." Russian Metallurgy (Metally) 2020, no. 3 (March 2020): 193–97. http://dx.doi.org/10.1134/s0036029520030106.
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Churyumov, A. Yu, A. V. Mikhailovskaya, A. D. Kotov, A. I. Bazlov, and V. K. Portnoi. "Development of mathematical models of superplasticity properties as a function of parameters of aluminum alloys of Al-Mg-Si system." Physics of Metals and Metallography 114, no. 3 (March 2013): 272–78. http://dx.doi.org/10.1134/s0031918x1303006x.
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Guo, Ran, En Qiang Lin, Rui Chun Duan, Gerard Mesmacque, and Abdelwaheb Amrouche. "Study of Fretting Fatigue Crack Initiation For Riveted Al 6xxx Components." Advanced Materials Research 33-37 (March 2008): 243–48. http://dx.doi.org/10.4028/www.scientific.net/amr.33-37.243.
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Riveting is a procedure widely used for fitting together two or more elements of a structure, that could be of the same or different material. In these assemblies the stress field is complex and a number of parameters, including effect of the geometrical discontinuities, contact between elements, tightening, material properties and applied load must be considered. The current work focuses on the study of fretting fatigue crack formation in common 6XXX aluminum alloys, used in land transportation equipments, and the determination of the characteristic crack initiation sites by means of both experimental and numerical methods. 3D finite element models were validated by the experimental results obtained with strain gauges. The influence of the contact friction coefficient at the fretting surface and fastening forces on the initiation of cracks, are discussed by the comparison of the different numerical results.
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Ganiev, Izatullo N., Suhrob E. Otajonov, Nasim F. Ibrohimov, and M. Mahmudov. "Temperature dependence of the heat capacity and change in the thermodynamic functions of strontium-alloyed AK1M2 alloy." Modern Electronic Materials 4, no. 3 (September 1, 2018): 119–24. http://dx.doi.org/10.3897/j.moem.4.3.38763.
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The temperature dependence of the specific heat capacity and change in the thermodynamic functions of strontium-alloyed ultrahigh-purity aluminum base AK1M2 alloy have been studied in “cooling” mode over the 298.15–900 K range. Mathematical models describing the evolution of these properties of the alloys in the abovementioned temperature range with change in alloying addition concentration have been obtained. The heat capacity, enthalpy and entropy of the alloys increase with temperature, decrease with an increase in the alloying addition concentration to 0.5 wt.% and grow with a further increase in the alloying addition concentration. The Gibbs energy of the alloys has an inverse dependence: it decreases with an increase in temperature and grows with an increase in the alloying addition concentration to 0.5 wt.%.
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Tynchenko, Vadim, Sergei Kurashkin, Valeriya Tynchenko, Vladimir Bukhtoyarov, Vladislav Kukartsev, Roman Sergienko, Viktor Kukartsev, and Kirill Bashmur. "Mathematical Modeling of Induction Heating of Waveguide Path Assemblies during Induction Soldering." Metals 11, no. 5 (April 24, 2021): 697. http://dx.doi.org/10.3390/met11050697.
Повний текст джерелаАнотація:
The waveguides used in spacecraft antenna feeders are often assembled using external couplers or flanges subject to further welding or soldering. Making permanent joints by means of induction heating has proven to be the best solution in this context. However, several physical phenomena observed in the heating zone complicate any effort to control the process of making a permanent joint by induction heating; these phenomena include flux evaporation and changes in the emissivity of the material. These processes make it difficult to measure the temperature of the heating zone by means of contactless temperature sensors. Meanwhile, contact sensors are not an option due to the high requirements regarding surface quality. Besides, such sensors take a large amount of time and human involvement to install. Thus, it is a relevant undertaking to develop mathematical models for each waveguide assembly component as well as for the entire waveguide assembly. The proposed mathematical models have been tested by experiments in kind, which have shown a great degree of consistency between model-derived estimates and experimental data. The paper also shows how to use the proposed models to test and calibrate the process of making an aluminum-alloy rectangular tube flange waveguide by induction soldering. The Russian software, SimInTech, was used in this research as the modeling environment. The approach proposed herein can significantly lower the labor and material costs of calibrating and testing the process of the induction soldering of waveguides, whether the goal is to adjust the existing process or to implement a new configuration that uses different dimensions or materials.
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Awd, Mustafa, Jan Johannsen, Shafaqat Siddique, Claus Emmelmann, and Frank Walther. "Qualification of selective laser-melted Al alloys against fatigue damage by means of measurement and modeling techniques." MATEC Web of Conferences 165 (2018): 02001. http://dx.doi.org/10.1051/matecconf/201816502001.
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Aluminum alloys processed through selective laser melting possess unique features of microstructure, defect morphology and mechanical properties. Constitution of fine cellular dendrites results from the high-cooling rate of the melt pool during the consolidation process. Investigation of the microstructure by scanning electron microscopy identifies supersaturation of Si particles as a secondary strengthening mechanism. On the contrary, platform heating that induces coarser microstructure leads to migration of Si particles from the Al matrix to the eutectic phase. As a result, tensile strength is reduced by ~3%, while fracture strain is increased by ~17%. Fine-grained structures exhibit a lower amount of plastic damage accumulation as well as delayed crack initiation as determined by the applied measurement techniques. Finite element models of the investigated configurations are obtained using scans of computed tomography under consideration of process-induced defects. Comparison of modeling and experimental results concluded that dominant fatigue damage mechanisms are related to the loading regime from low-cycle (LCF) to very-high-cycle fatigue (VHCF). Thus, process-inherent features of microstructure and porosity have different quantitative effects concerning the applied load. In VHCF, a material configuration with platform heating possesses an improved fatigue strength by ~33% at 1E9 cycles, concerning the material configuration without platform heating.
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Li, Haoran, Jiadong Wang, Juncheng Wang, Ming Hu, and Yan Peng. "Lifetime Assessment for Multiaxial High-Cycle Fatigue Using Twin-Shear Unified Yield Criteria." Metals 11, no. 8 (July 24, 2021): 1178. http://dx.doi.org/10.3390/met11081178.
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In this paper, a life prediction model associated with maximum principal stress and equivalent shear amplitude based on twin-shear unified yield criterion for multiaxial high-cycle fatigue is proposed. The equivalent shear amplitude is the normalized format of the equivalent shear amplitude based on clusters of yield criteria embodying Tresca and the linearization of Huber-von Mises, extending the application to metallic materials. Simultaneously, the effect of mean stress on multiaxial high-cycle fatigue is considered in the proposed model. As an assessment of the new prediction model, the criterion is compared with experimental data of aluminum alloy LY12CZ and carbon structural steel SM45C published in the relevant literature, which shows that most of the data are located within an error range of less than two times the data and are in good agreement with the experiment. Moreover, the proposed model is also compared with other models, such as McDiarmid, Liu, and Freitas, to validate its competitiveness.
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Raja, Allavikutty, Sai Teja Chukka, and Rengaswamy Jayaganthan. "Prediction of Fatigue Crack Growth Behaviour in Ultrafine Grained Al 2014 Alloy Using Machine Learning." Metals 10, no. 10 (October 9, 2020): 1349. http://dx.doi.org/10.3390/met10101349.
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The present work investigates the relationship between fatigue crack growth rate (da/dN) and stress intensity factor range (∆K) using machine learning models with the experimental fatigue crack growth rate (FCGR) data of cryo-rolled Al 2014 alloy. Various machine learning techniques developed recently provide a flexible and adaptable approach to explain the complex mathematical relations especially, non-linear functions. In the present work, three machine algorithms such as extreme learning machine (ELM), back propagation neural networks (BPNN) and curve fitting model are implemented to analyse FCGR of Al alloys. After tuning of networks with varying hidden layers and number of neurons, the trained models found to fit well to the tested data. The three tested models are compared with each other over the training as well as testing phase. The mean square error for predicting the FCG of cryo-rolled Al 2014 alloy by BPNN, ELM and curve fitting methods are 1.89, 1.84 and 0.09 respectively. While the ELM models outperform the rest of models in terms of training time, curve fitting model showed best performance in terms of accuracy over testing data with least mean square error (MSE). In terms of local optimisation, back propagation neural networks excel the other two models.
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Dudareva, N. Yu, E. I. Ustimova, and R. F. Gallyamova. "Corrosion Resistance of MAO Coatings on Al-Si Alloys." Solid State Phenomena 299 (January 2020): 749–54. http://dx.doi.org/10.4028/www.scientific.net/ssp.299.749.
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The paper presents the results of an experimental study of the influence of micro-arc oxidation (MAO) on the parameters and the corrosion resistance of MAO-treated surfaces on a high-silicon aluminum alloy, M244 (Si ~ 25 %). The article describes the study methodology, comprising forming a coating on the surface of laboratory samples by means of MAO at different process modes and the study of their parameters, properties, and corrosion resistance. The experiments were conducted in accordance with the 23 full factorial experiment design theory. The MAO process was carried out using a silicate-alkaline electrolyte. MAO factors were as follows: the concentration of the electrolyte components (potassium hydroxide – KOH and liquid glass – Na2SiO3) and electrical parameters of the process, determined by the capacitor capacitance of the processing unit. The samples were tested to define thickness, porosity and micro-hardness of the MAO layer. Being corroded in a corrosive solution for 144 hours, their corrosion resistance was estimated by a mass corrosion rate. The data obtained made it possible to form mathematical models, based on the dependence of corrosion resistance, thickness, porosity and micro-hardness on the process factors. A verification of the obtained models was carried out to determine adequacy and their analysis. Conclusions on the extent of the MAO effect on the corrosion resistance of the samples were drawn. MAO modes were stated to have a significant impact on the corrosion resistance of the samples. MAO should be carried out using low electrolyte concentrations and a low-capacity processing unit for improved corrosion-protective properties of the coating on the M244 (Mahle) aluminum alloy. It is necessary to increase the concentration of the electrolyte components and the processing unit capacity, to obtain a thicker coating with low micro-hardness and porosity.
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Jiang, Yanyao, and Peter Kurath. "An Investigation of Cyclic Transient Behavior and Implications on Fatigue Life Estimates." Journal of Engineering Materials and Technology 119, no. 2 (April 1, 1997): 161–70. http://dx.doi.org/10.1115/1.2805989.
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Current research focuses on proportional cyclic hardening and non-Massing behaviors. The interaction of these two hardenings can result in the traditionally observed overall softening, hardening or mixed behavior exhibited for fully reversed strain controlled fatigue tests. Proportional experiments were conducted with five materials, 304 stainless steel, normalized 1070 and 1045 steels, and 7075-T6 and 6061-T6 aluminum alloys. All the materials display similar trends, but the 304 stainless steel shows the most pronounced transient behavior and will be discussed in detail. Existing algorithms for this behavior are evaluated in light of the recent experiments, and refinements to the Armstrong-Frederick class of incremental plasticity models are proposed. Modifications implemented are more extensive than the traditional variation of yield stress, and a traditional strain based memory surface is utilized to track deformation history. Implications of the deformation characteristics with regard to fatigue life estimation, especially variable amplitude loading, will be examined. The high-low step loading is utilized to illustrate the effect of transient deformation on fatigue life estimation procedures, and their relationship to the observed and modeled deformation.
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Lados, Diana A., and Diran Apelian. "The effect of residual stress on the fatigue crack growth behavior of Al-Si-Mg cast alloys—Mechanisms and corrective mathematical models." Metallurgical and Materials Transactions A 37, no. 1 (January 2006): 133–45. http://dx.doi.org/10.1007/s11661-006-0159-y.
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Volkov, I. A,, L. A. Igumnov, D. N. Shishulin, and A. A. Belov. "EVALUATION OF THE RESOURCE CHARACTERISTICS OF POLYCRYSTALLINE STRUCTURAL ALLOYS UNDER CYCLIC THERMOMECHANICAL LOADING." Problems of Strength and Plasticity 83, no. 4 (2021): 481–504. http://dx.doi.org/10.32326/1814-9146-2021-83-4-481-504.
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The main physical regularities of complex thermoviscoplastic deformation and accumulation of damage in structural materials (metals and their alloys) under various modes of cyclic combined thermomechanical loading and mathematical models of these processes are considered. A mathematical model of the mechanics of a damaged medium has been developed, which makes it possible to simulate the cyclic viscoelastoplastic behavior and determine the resource characteristics of polycrystalline structural alloys under the combined action of degradation mechanisms that combine material fatigue and creep. The model is based on the joint integration of equations describing the kinetics of the stress-strain state and damage accumulation processes. The final relation to the model is the strength criterion, the fulfillment of which corresponds to the formation of a macrocrack. The plasticity equations are based on the basic principles of the flow theory. To describe the creep process in the stress space, a family of equipotential creep surfaces of the corresponding radius and having a common center is introduced. The relationship between the creep equations and the thermoplasticity equations describing “instantaneous” plastic deformations is carried out at the loading stage through the stress deviator and the corresponding algorithm for determining and at the loading stage by means of certain relationships between “temporary” and “instantaneous” scalar and tensor quantities. At the stage of development of damage scattered throughout the volume, the effect of damage on the physical and mechanical characteristics of the material is observed. This influence can be taken into account by introducing effective stresses. In the general case, stresses, plastic strains, and creep strains are determined by integrating the thermal creep equations by the four-point Runge-Kutta method with correction of the stress deviator and subsequent determination of stresses according to the thermoplasticity equations, taking into account the average creep strain rate at a new time. The relationships that simulate the accumulation of damage are based on the energy approach to determining the resource characteristics. The kinetics of fatigue damage accumulation is based on the introduction of a scalar parameter of damage to a structural material and a unified model form for representing the degradation mechanism under fatigue and creep conditions. The influence of scattered damage on the physical and mechanical characteristics of the material is taken into account by introducing effective stresses. The results of numerical simulation of cyclic thermoplastic deformation and accumulation of fatigue damage in heat-resistant alloys (Haynes188) under combined thermomechanical loading are presented. Particular attention is paid to the issues of modeling the processes of cyclic thermoplastic deformation and the accumulation of fatigue damage for complex deformation processes accompanied by the rotation of the main areas of stress and strain tensors.
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Gariboldi, Elisabetta, Marco Verani, and Christian Riva. "Modelling of Phase Evolution during Aluminizing Processes." Advanced Materials Research 278 (July 2011): 228–33. http://dx.doi.org/10.4028/www.scientific.net/amr.278.228.
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Aluminizing processes are a well-known set of techniques industrially adopted to enrich in aluminum the surface layers of Ni-based alloys, thus improving their resistance to environmental interactions at high temperature. The results of aluminizing are described in terms of the presence, compositions and thickness of the sequence of the resulting surface diffusion layers. A combination of difficulties arising both from the mathematical and the material side restricted the number of available user-friendly models and their applicability to specific alloys or process conditions. The aim of the research work here presented is to overcome part of these difficulties. A synthesis of some well-established models was implemented in a robust numerical algorithm, that automatically prevents instabilities and convergence problems. Such numerical algorithm has been experimentally validated by comparing the results to the experimentally measured composition of profiles obtained for a set of vapor-phase aluminized samples of commercially pure Ni. The model was then applied to predict the effects of the process temperature and of the chemical composition of the surface.
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da Silva, Andre Luiz Nunis, Celia Aparecida Lino dos Santos, Rogério de Melo Riberio de Araújo, Dominic Feldhaus, Bernd Friedrich, Fernando José Gomes Landgraf, and Roberto Guardani. "Model and Mechanism of Anode Effect of an Electrochemical Cell for Nd or (Nd, Pr) Reduction." Metals 12, no. 3 (March 15, 2022): 498. http://dx.doi.org/10.3390/met12030498.
Повний текст джерелаАнотація:
The anode effect can occur during neodymium and didymium oxide electrowinning, causing a surge in the electrochemical cell voltage, interrupting the process, and increasing the greenhouse gas emissions. In this work, we develop a mathematical model, based on the mass balance of gas bubbles evolving from the anode, to understand the influence of some process parameters on the anode effect. The anode effect occurs due to bubble coverage and limitations on the mass transfer of the oxide species. Variables such as current density, oxide content, viscosity, and electrolyte composition play an important role in the anodic process. Finally, we propose a mechanism for the occurrence of the anode effect during Nd or Di (Nd–Pr) oxide electrolytic reduction based on models used in aluminum electrolysis.
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Si-Jian, Lin, Long Wei, Tian Da-Qing, and Liao Jun-Bi. "A new fatigue damage accumulation model considering loading history and loading sequence based on damage equivalence." International Journal of Damage Mechanics 27, no. 5 (March 27, 2017): 707–28. http://dx.doi.org/10.1177/1056789517701531.
Повний текст джерелаАнотація:
In this study, a new nonlinear fatigue damage accumulation model is proposed to consider the effects of loading history and loading sequence under multi-level stress loading based on the Miner–Palmgren rule and S-N curve. By using damage equivalence, the new model is simplified and another form of the model is given. This model improves the application of the traditional Miner–Palmgren rule, by considering not only the loading sequence effect but also the loading history effect. The methods for calculating the degree of safety of specimens and cumulative damage of low-amplitude loads are also presented. Applicability of the new model is validated by predicting the fatigue life of 16Mn and 45 steel specimens under two-level stress loading. Further validation is carried out for the case of 41Cr4 and Aluminum alloys 6082 T6 under multi-level stress loading, and the strengthening and damaging effect of low-amplitude loads is considered. Comparing with the Miner–Palmgren rule and some new models, this new model gives more accurate and reliable prediction.
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Калінін, Борис Петрович. "Оцінка втомної міцності при асиметричному циклі навантаження". Aerospace technic and technology, № 1 (24 лютого 2022): 51–56. http://dx.doi.org/10.32620/aktt.2022.1.06.
Повний текст джерелаАнотація:
The object of study in the article is the individual parts of aircraft units, applied to loads that change over time. The subject of study is models that describe fatigue resistance under asymmetric loads. The goal is to develop a fairly simple engineering technique for detecting parts of aircraft units operating under an asymmetric loading cycle. Tasks: general analysis of many approaches to design cycles before the destruction of parts of aircraft units, production with an asymmetric loading cycle; select calculations acceptable for practical calculations, determine the endurance limit under a symmetrical loading cycle for steels and aluminum alloys used in aircraft units; select a calculation to calculate the maximum amount of asymmetric cycle. Methods used engineering analysis of methods for constructing a fatigue curve for an asymmetric speed change cycle; calculation of the endurance limit for a symmetrical cycle of change depending on the properties of materials based on the results of experimental selection and calculation of the endurance limit of materials to calculate the endurance limits of materials; the finite element method for counting and increasing dimensions in parts in the Simulation software package in Solidworks packages. The obtained results are obtained: an equation is chosen for the structure of the curve with an asymmetric cycle of stress change, given mechanical properties of the material; selections are selected for calculation with acceptable accuracy according to the specified properties of the endurance limits of materials with a symmetrical loading cycle of steels and aluminum alloys used in aircraft units; calculations were selected to calculate the limiting value of the asymmetric oscillation of the cycle; a method for determining the constants of the Weibull distribution for the fatigue curve under an asymmetric load cycle is proposed. Conclusion: an engineering technique has been developed for determining the resistance of parts of aircraft units operating under loads that change over time according to an asymmetric cycle.
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Xue, Fei, Diqiu He, and Haibo Zhou. "Effect of Ultrasonic Vibration in Friction Stir Welding of 2219 Aluminum Alloy: An Effective Model for Predicting Weld Strength." Metals 12, no. 7 (June 28, 2022): 1101. http://dx.doi.org/10.3390/met12071101.
Повний текст джерелаАнотація:
Friction stir welding (FSW) is today used as a premier solution for joining non-ferrous metals, although there are many limitations in its application. One of the objectives of this study was to propose an innovative welding technique, namely ultrasonic-assisted friction stir welding (UAFSW) with longitudinal ultrasonic vibration applied to the stirring head. In this paper, UAFSW mechanical properties and microstructure analysis were performed to demonstrate that the fluidity of the weld area was improved and the strengthened phase organization was partially preserved, due to the application of ultrasonic vibration. The addition of 1.8 kW of ultrasonic vibration at 1200 rpm and 150 mm/min welding parameters resulted in a 10.5% increase in the tensile strength of the weld. The ultimate tensile strength of 2219 aluminum alloy UAFSW was analyzed and predicted using mathematical modeling and machine learning techniques. A full factorial design method with multiple regression, random forest, and support vector machine was used to validate the experimental results. In predicting the tensile behavior of UAFSW joints, by comparing the evaluation metrics, such as R2, MSE, RMSE, and MAE, it was found that the RF model was 22% and 21% more accurate in the R2 metric compared to other models, and RF was considered as the best performing machine learning method.
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Maglić, Leon, Dejan Marić, Tomislav Šolić, and Ivan Samardžić. "Optimization of Synchropulsed MIG Welding Process Parameters for Welding of AW 5083 Sheets." Materials 15, no. 9 (April 23, 2022): 3078. http://dx.doi.org/10.3390/ma15093078.
Повний текст джерелаАнотація:
Metal inert gas (MIG) welding is one of the processes most commonly used for joining metals, especially for joining aluminum and its alloys. The application of a pulsed current in an electric arc allows better controllability of the molten droplets and the arc transition, which subsequently leads to welds with characteristic flaky joints of better quality. In this paper, the optimization of parameters for welding aluminum alloys using the synchropulse welding process is investigated. By observing the input variables that have the greatest influence on the change in appearance of the welding current characteristics (delta wire feed from 0.1 to 6.0 m/min, frequency F from 0.5 to 3 Hz, duty cycle from 10% to 90%), it is possible to perform an optimization to achieve the desired output values. The output variables of the experiments are defined as insufficient/excessive throat thickness (mm), depth of penetration (mm), and weld width (mm); and for the desired quality of the welded joint the most acceptable range of its values is selected, the numerical optimization implementation. The experiment has shown that the delta wire feed has the greatest effect on the observed properties, while the influence of frequency F and duty cycle is somewhat smaller, but the factors responsible for the observed output properties are still significant. From all this, it is possible to select specific values of these input variables to define the best possible observed properties and to determine the characteristics of the defined mathematical models.