To see the other types of publications on this topic, follow the link: Crack Propagation (Material Science).
Journal articles on the topic 'Crack Propagation (Material Science)'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 journal articles for your research on the topic 'Crack Propagation (Material Science).'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse journal articles on a wide variety of disciplines and organise your bibliography correctly.
1
Bi, Yueqi, Xiaoming Yuan, Mingrui Hao, Shuai Wang, and He Xue. "Numerical Investigation of the Influence of Ultimate-Strength Heterogeneity on Crack Propagation and Fracture Toughness in Welded Joints." Materials 15, no. 11 (May 27, 2022): 3814. http://dx.doi.org/10.3390/ma15113814.
Full textAbstract:
The mechanical properties of dissimilar metal-welded joint materials are heterogeneous, which is an obstacle to the safety evaluation of key welded structures. The variation of stress–strain conditions at the crack tip caused by mismatch of material mechanical properties in dissimilar metal-welded joints is an important factor affecting crack propagation behavior. To understand the influence of uneven distribution of ultimate strength of the base metal and the welded metal on the crack propagation path, fracture toughness, as well as the mechanical field at the crack tip in the small-scale yield range, the user-defined field variable subroutine method is used to express continuous variation characteristics of welded joint ultimate strength in finite element software. In addition, the J-integral during crack propagation is calculated, and the effect of the ultimate strength on the J-integral and the stress field at the crack tip are analyzed. The results show that as the crack propagation direction is perpendicular to the direction of ultimate strength, the gradient of ultimate strength increases from |Gy|= 50 to |Gy|= 100 MPa/mm, the crack deflection angle increases by 0.018%, and the crack length increases by 1.46%. The fracture toughness of the material decreased slightly during crack propagation. Under the condition that the crack propagation direction is the same as the direction of ultimate strength, the crack propagation path is a straight line. As the gradient of ultimate strength increases from Gx = 50 to Gx = 100 MPa/mm, the crack propagation length decreases by 5.17%, and the slope of fracture toughness curve increases by 51.63%. On the contrary, as the crack propagates to the low ultimate strength side, the crack propagation resistance decreases, the ultimate strength gradient increases from Gx = −100 to Gx = −50 MPa/mm, and the slope of the fracture toughness curve decreases by 51.01%. It is suggested to consider the relationship between crack growth behavior and ultimate strength when designing and evaluating the structural integrity of cracks at the material interface of dissimilar metal-welded joints.
2
Yang, Fu-qiang, He Xue, Ling-yan Zhao, and Xiu-rong Fang. "Effects of Welded Mechanical Heterogeneity on Interface Crack Propagation in Dissimilar Weld Joints." Advances in Materials Science and Engineering 2019 (February 3, 2019): 1–10. http://dx.doi.org/10.1155/2019/6593982.
Full textAbstract:
The stress and strain status associated with the material properties is one of the main factors affecting stress corrosion cracking (SCC) of structural components in nuclear power plants (NPPs). In many SCC prediction models, the stress intensity factor calculated with homogeneous materials is used to characterize the crack tip stress state. However, the mechanical and material properties in weld joints are heterogeneous, which will produce the discontinuous distribution of stress and strain nearby crack tip and affect the crack propagation. To understand the material mechanical heterogeneity effects on interface crack propagation, the specimens with ultimate tensile strength mismatch and elastic modulus mismatch were studied by using an extended finite element method (XFEM). The results indicate that the interface crack extension is easy to occur in the specimens with larger ultimate tensile strength mismatch, while the elastic modulus mismatch has little effects on crack extension. The different interface cracks in the dissimilar metal weld joints of the reactor pressure vessel used in NPPs tend to deviate from the initial direction into alloy 182, and the interface crack propagation path fluctuation is small.
3
Han, Du, Hongwei Fan, Chengzeng Yan, Tie Wang, Yu Yang, Sajid Ali, and Gang Wang. "Heat Conduction and Cracking of Functionally Graded Materials Using an FDEM-Based Thermo-Mechanical Coupling Model." Applied Sciences 12, no. 23 (November 30, 2022): 12279. http://dx.doi.org/10.3390/app122312279.
Full textAbstract:
In this paper, the steady-state and transient heat transfer processes of functionally graded materials (FGMs) are analyzed using a coupled thermo-mechanical model in a GPU parallel multiphysics finite–discrete element software, namely MultiFracS. First, the coupled model to handle the heat transfer problem of heterogeneous materials is verified. Then, the advantages and disadvantages of FGMs and composite materials in response to thermal shock loads are compared and the results indicate that FGMs can overcome extreme environments better than composite materials. Finally, the influence of the geometric distribution characteristics of the double-edge cracks in the gradient material plate on the crack propagation is analyzed. The simulation results show that the interaction between the cracks affects the crack propagation path under the thermal load. The inclination angle and spacing of double-edge cracks greatly influence crack propagation. Specifically, a larger inclination angle and spacing can lead to a smaller crack propagation angle. The approach in this paper provides a new quantitative tool for investigating the thermal, elastic, and cracking of functionally graded materials.
4
Li, Tong, Zhenting Yang, Chenghui Xu, Xinsheng Xu, and Zhenhuan Zhou. "A Phase Field Approach to Two-Dimensional Quasicrystals with Mixed Mode Cracks." Materials 16, no. 10 (May 9, 2023): 3628. http://dx.doi.org/10.3390/ma16103628.
Full textAbstract:
Quasicrystals (QCs) are representatives of a novel kind of material exhibiting a large number of remarkable specific properties. However, QCs are usually brittle, and crack propagation inevitably occurs in such materials. Therefore, it is of great significance to study the crack growth behaviors in QCs. In this work, the crack propagation of two-dimensional (2D) decagonal QCs is investigated by a fracture phase field method. In this method, a phase field variable is introduced to evaluate the damage of QCs near the crack. Thus, the crack topology is described by the phase field variable and its gradient. In this manner, it is unnecessary to track the crack tip, and therefore remeshing is avoided during the crack propagation. In the numerical examples, the crack propagation paths of 2D QCs are simulated by the proposed method, and the effects of the phason field on the crack growth behaviors of QCs are studied in detail. Furthermore, the interaction of the double cracks in QCs is also discussed.
5
Liu, Taoying, Mengyuan Cui, Qing Li, Shan Yang, Zhanfu Yu, Yeshan Sheng, Ping Cao, and Keping Zhou. "Fracture and Damage Evolution of Multiple-Fractured Rock-like Material Subjected to Compression." Materials 15, no. 12 (June 18, 2022): 4326. http://dx.doi.org/10.3390/ma15124326.
Full textAbstract:
Multiple compression tests on rock-like samples of pre-existing cracks with different geometries were conducted to investigate the strength properties and crack propagation behavior considering multi-crack interactions. The progressive failure process of the specimens was segmented into four categories and seven coalescence modes were identified due to different crack propagation mechanisms. Ultimately, a mechanical model of the multi-crack rock mass was proposed to investigate the gradual fracture and damage evolution traits of the multi-crack rock on the basis of exploring the law of the compression-shear wing crack initiation and propagation. A comparison between theory and experimental results indicated that the peak strength of the specimens with multiple fractures decreased initially and subsequently increased with the increase in the fissure inclination angles; the peak strength of specimens decreased with the increase in the density of fissure distribution.
6
Gao, Ruipeng, Mengmeng Liu, Bing Wang, Yiran Wang, and Wei Shao. "Influence of Stress Intensity Factor on Rail Fatigue Crack Propagation by Finite Element Method." Materials 14, no. 19 (September 30, 2021): 5720. http://dx.doi.org/10.3390/ma14195720.
Full textAbstract:
Wheel rail rolling contact fatigue is a very common form of damage, which can lead to uneven rail treads, railhead nuclear damage, etc. Therefore, ANSYS software was used to establish a three-dimensional wheel–rail contact model and analyze the effects of several main characteristics, such as the rail crack length and crack propagation angle, on the fatigue crack intensity factor during crack propagation. The main findings were as follows: (1) With the rail crack length increasing, the position where the crack propagated by mode I moved from the inner edge of the wheel–rail contact spot to the outer edge. When the crack propagated to 0.3–0.5 mm, it propagated to the rail surface, causing the rail material to peel or fall off and other damage. (2) When the crack propagation angle was less than 30°, the cracks were mainly mode II cracks. When the angle was between 30 and 70°, the cracks were mode I–II cracks. When the angle was more than 70°, the cracks were mainly mode I cracks. When the crack propagation angle was 60°, the equivalent stress intensity factor reached the maximum, and the rail cracks propagated the fastest.
7
Smith, B. J., and A. R. Marder. "Corrosion-Fatigue (Circumferential) Cracking in Cr-Mo Low Alloy Boiler Tube Steels: Part 1—Initiation and Propagation." Journal of Engineering Materials and Technology 114, no. 3 (July 1, 1992): 265–69. http://dx.doi.org/10.1115/1.2904171.
Full textAbstract:
The metallurgical mechanism responsible for the initiation and propagation of circumferentially oriented, fireside cracks on waterwall boiler tubes was investigated. The materials studied were Cr-Mo low alloy steels in the as-received and post-service (exhibited cracking) condition. It was determined that cracks were initiated by a corrosion/fatigue interactive mechanism at the fireside tube surface. The corrosion mechanism is sulfidation while the material fatigue degradation occurs due to thermal stress cycles. Crack propagation occurs by an environmentally assisted thermal fatigue crack propagation mechanism.
8
Zhang, Yongpeng, Guangchun Xiao, Chonghai Xu, Tingting Zhou, Mingdong Yi, and Zhaoqiang Chen. "Cohesive Element Model for Fracture Behavior Analysis of Al2O3/Graphene Composite Ceramic Tool Material." Crystals 9, no. 12 (December 11, 2019): 669. http://dx.doi.org/10.3390/cryst9120669.
Full textAbstract:
The microstructure model of Al2O3/graphene (AG) composite ceramic tool material is established based on Voronoi tessellation. The cohesive element method was used to simulate the crack growth of AG. The effect of cohesive parameters at the grain boundary of Al2O3 and graphene on the crack propagation was investigated. The results show that the grain strength of graphene is too high, the crack propagation to graphene grains will be hindered and cannot propagate forward. Cracks tend to spread along the paths where the crack propagation drive force was high and the resistance was low. When the interface strength between Al2O3 and graphene was at the weak interface, the crack propagation path and length were relatively straight and short. The average energy release rate G C is 1.042 × 10−3 J/m2, which is 2.4% higher than that of single-phase Al2O3 ceramic tool materials. However, if the interface strength between Al2O3 and graphene was at the strong interface, the crack propagated along graphene particles for a short distance, consuming a large amount of fracture energy. Furthermore, the crack will deflect around graphene grains, which increases the crack propagation length. The average energy release rate G C is 1.039 × 10−3 J/m2, which is 2% higher than that of single-phase Al2O3 ceramic tool materials.
9
Wünsche, Michael, Jan Sladek, Vladimir Sladek, Chuanzeng Zhang, and Miroslav Repka. "Dynamic Wave Propagation in Fiber Reinforced Piezoelectric Composites with Cracks." International Journal of Computational Methods 16, no. 06 (May 27, 2019): 1840021. http://dx.doi.org/10.1142/s0219876218400212.
Full textAbstract:
This paper presents the transient dynamic analysis of micro-cracks of arbitrary shape in two-dimensional, linear piezoelectric fiber reinforced composite materials. Interface cracks between fiber and matrix as well as cracks inside the matrix and fibers are investigated. For this purpose, a symmetric Galerkin time-domain boundary element method in conjunction with a multi-domain technique is developed. The time-domain fundamental solutions for linear piezoelectric materials are applied. The time discretization is performed by a collocation method. An explicit time-stepping scheme is obtained to compute the discrete boundary data including the generalized crack-opening-displacements (CODs). Iterative solution algorithms are implemented to solve the nonlinear semi-permeable electrical crack-face boundary conditions and for a crack-face contact analysis at time-steps when a physically unacceptable crack-face intersection occurs. Several numerical examples are presented to reveal the influences of the micro-cracks, the material combinations and the transient dynamic loading on the intensity factors and the scattered wave fields.
10
Sohel, Shamsul Huda, Md Al Amin Hossain, Debashis Datta, and Md Fazlul Huq. "Probabilistic Assessment of Crack Failure of Reactor Pressure Vessel (RPV) Cladding Material." Journal of Bangladesh Academy of Sciences 41, no. 2 (January 29, 2018): 237–45. http://dx.doi.org/10.3329/jbas.v41i2.35501.
Full textAbstract:
To design a Reactor Pressure Vessel (RPV), material property like crack must be considered as it is an unavoidable property of materials. Presence of crack in materials must be kept within limit to prevent material’s failure. So, crack propagation must be analyzed and observed. In this paper, crack propagation due to stress and materials fracture toughness of reactor pressure vessel cladding has been observed to estimate cumulative probability of crack failure using Probabilistic Fracture Mechanics (PFM). Average crack size is guessed as 3 mm and geometry factor is considered as 1.12 to analyze edge crack. Final crack analysis range has been found to be 1.8 mm with crack propagation rate of ± 30% of its average size. Variation of critical crack size and crack initiation point for several design stresses and fracture toughness has been investigated with probabilistic fracture mechanics technique. The observed crack propagation by calculating final crack size and the cumulative crack failure probability of the reactor pressure vessel materials are presented in this work.Journal of Bangladesh Academy of Sciences, Vol. 41, No. 2, 237-245, 2017
11
Zheng, Lulin, Hao Liu, Yujun Zuo, Quanping Zhang, Wei Lin, Qing Qiu, Xiaorong Liu, and Ziqi Liu. "Fractal Study on the Failure Evolution of Concrete Material with Single Flaw Based on DIP Technique." Advances in Materials Science and Engineering 2022 (February 4, 2022): 1–15. http://dx.doi.org/10.1155/2022/6077187.
Full textAbstract:
Crack inclination and material heterogeneity have important effects on the meso-mechanical mechanism and macroscopic mechanical behavior of rock-like materials. In order to study the failure characteristics of shotcrete body during the process of using shotcrete bolt mesh support in the deep fractured rock mass of Lannigou Gold Mine, this paper combined the Digital Image Processing Technique (DIP) and RFPA2D (Rock Failure Process Analysis System) to establish a real meso-structure numerical model of concrete with different inclination angle cracks, simulating its crack propagation law and failure process, and studied the influence of crack geometry distribution and meso-heterogeneity on the effect of concrete structure. The findings reveal that the crack inclination angle has a substantial impact on concrete materials' compressive strength and elastic modulus, and both of them all show a nonlinear increase with the increase of crack angle; Because of the inhomogeneity of the materials, the inclination and propagation pathways of wing cracks are random, and the aggregate inhibits crack initiation and propagation. The wing crack's initiation position moves closer to the tip as the crack inclination angle increases, and the length gets shorter; Acoustic emission(AE) evolution characteristics are similar in samples with varying dip angles. In the early stages of loading, the AE energy is minimal, and increases rapidly when approaching the peak stress. The fractal dimension was used to describe the damage evolution process inside the material, and a damage variable index (ω) based on the fractal theory was proposed. The more the ω, the greater the material's degree of degradation. The proposed index provided a new method for quantitative study of the damage evolution characteristics of rock-like materials. It has guiding significance for the research on the stability of wet shotcrete in the deep fractured rock mass of Lannigou Gold Mine.
12
Ozelo, R. R. M., P. Sollero, and A. L. A. Costa. "An Alternative Technique to Evaluate Crack Propagation Path in Hyperelastic Materials." Tire Science and Technology 40, no. 1 (March 1, 2012): 42–58. http://dx.doi.org/10.2346/1.3684484.
Full textAbstract:
Abstract REFERENCE: R. R. M. Ozelo, P. Sollero, and A. L. A. Costa, “An Alternative Technique to Evaluate Crack Propagation Path in Hyperelastic Materials,” Tire Science and Technology, TSTCA, Vol. 40, No. 1, January–March 2012, pp. 42–58. ABSTRACT: The analysis of crack propagation in tires aims to provide safety and reliable life prediction. Tire materials are usually nonlinear and present a hyperelastic behavior. Therefore, the use of nonlinear fracture mechanics theory and a hyperelastic material constitutive model are necessary. The material constitutive model used in this work is the Mooney–Rivlin. There are many techniques available to evaluate the crack propagation path in linear elastic materials and estimate the growth direction. However, most of these techniques are not applicable to hyperelastic materials. This paper presents an alternative technique for modeling crack propagation in hyperelastic materials, based in the J-Integral, to evaluate the crack path. The J-Integral is an energy-based parameter and is applicable to nonlinear materials. The technique was applied using abaqus software and compared to experimental tests.
13
Pang, Yong, Dingyu Li, Xin Li, Ruzhuan Wang, and Xiang Ao. "Phase-Field Simulation of Temperature-Dependent Thermal Shock Fracture of Al2O3/ZrO2 Multilayer Ceramics with Phase Transition Residual Stress." Materials 16, no. 2 (January 11, 2023): 734. http://dx.doi.org/10.3390/ma16020734.
Full textAbstract:
Compared with single-phase ceramics, the thermal shock crack propagation mechanism of multiphase layered ceramics is more complex. There is no experimental method and theoretical framework that can fully reveal the thermal shock damage mechanism of ceramic materials. Therefore, a multiphase phase-field fracture model including the temperature dependence of material for thermal shock-induced fracture of multilayer ceramics is established. In this study, the effects of residual stress on the crack propagation of ATZ (Al2O3-5%tZrO2)/AMZ (Al2O3-30%mZrO2) layered ceramics with different layer thickness ratios, layers, and initial temperatures under bending and thermal shock were investigated. Simulation results of the fracture phase field under four-point bending are in good agreement with the experimental results, and the crack propagation shows a step shape, which verifies the effectiveness of the proposed method. With constant thickness, high-strength compressive stress positively changes with the layer thickness ratio, which contributes to crack deflection. The cracks of the ceramic material under thermal shock have hierarchy and regularity. When the layer thickness ratio is constant, the compressive residual stress decreases with the increase in the layer number, and the degree of thermal shock crack deflection decreases.
14
GHERIB, SAMIA, HAMID SATHA, JEAN MARC PELLETIER, LAURENT CHAZEAU, and DJAMEL FRIHI. "CRACKING BEHAVIOR OF CARBON BLACK FILLED ELASTOMERS." International Journal of Nanoscience 09, no. 06 (December 2010): 557–61. http://dx.doi.org/10.1142/s0219581x10007241.
Full textAbstract:
The study of crack propagation in rubber has a very high economic significance but is still not well understood. For this purpose the main objective of this work is to study the fracture behavior of two types of rubber: the NR, which crystallizes under stress and the noncrystallizing SBR. To study the cracking behavior of materials we have made tests of cracking follow-up. The mode of crack propagation has been studied in terms of fillers ratio and traction speed. The unfilled SBR and NR showed simple lateral propagation independently of the test speed, whereas the mode of cracking of filled materials was very influenced by the parameters mentioned previously. The filled SBR can present important deviations of the crack when the fillers ratio is sufficiently high; this deviation is even more pronounced when the speed increases. On the other hand, the natural rubber which crystallizes under stress showed particular mode of propagation characterized by the appearance of longitudinal cracks. This mode of cracking is much more important at low speeds than at the high speeds. It is proposed that the fillers increase the breaking strength of a noncrystallizing material and allows that the crack takes a deviated way if the fillers ratio is sufficiently high. But if it is a material which crystallize like the NR, crystallization and fillers will act simultaneously and the material will be much more resistant which gives rise to a particular mechanism which is the appearance of the longitudinal cracks before the catastrophic rupture.
15
Shen, Qingqing, Qiuhua Rao, Quan Zhang, Zhuo Li, Dongliang Sun, and Wei Yi. "A New Method for Predicting Double-Crack Propagation Trajectories of Brittle Rock." International Journal of Applied Mechanics 13, no. 02 (March 2021): 2150026. http://dx.doi.org/10.1142/s1758825121500265.
Full textAbstract:
Multi-crack propagation is investigated mainly by experimental measurement and little by theoretical prediction. The classical fracture criteria can better predict tensile fracture under arbitrary loading conditions (pure tensile, pure shear and mixed-mode), but have difficulty in predicting shear fracture. In this paper, Mode I and Mode II SIFs of branch-cracks initiated by the original cracks were calculated by the complex function and superposition method, and a new theory of multi-crack propagation was established based on the criterion of maximum tensile-shear SIF ratio. Theoretical results of two collinear cracks under uniaxial compression show that the cracks initiate more easily at [Formula: see text] (the crack inclination angle) than other angles. Coalescence of branch-crack only occurs at [Formula: see text] with the maximum crack propagation length. Peak stress [Formula: see text] reaches minimum when [Formula: see text] (inner friction angle of rock), and the larger the [Formula: see text], the closer to the compressive strength of rock the [Formula: see text]. Mechanism of the crack initiation and propagation are all Mode I under uniaxial compression. Uniaxial compressive test results of red sandstone (the rock material is assumed to be homogeneous) pre-cracked specimens agree well with predicted results of the crack initiation, stable and unstable propagation, which can prove the validity of the new multi-crack propagation prediction method.
16
Sallaba, Finn, Franziska Rolof, Sören Ehlers, Carey Leroy Walters, and Moritz Braun. "Relation between the Fatigue and Fracture Ductile-Brittle Transition in S500 Welded Steel Joints." Metals 12, no. 3 (February 23, 2022): 385. http://dx.doi.org/10.3390/met12030385.
Full textAbstract:
The formation and propagation of cracks occur through irreversible dislocation movements at notches, material defects, and grain boundaries. Since this process is partly thermally controlled, the resistance to dislocation movements at low temperatures increases. This slows both fatigue initiation and fatigue crack propagation. From recent experimental data, it can be seen that fatigue crack growth is accelerated below the fatigue transition temperature (FTT) that correlates with the ductile-brittle transition temperature (DBTT) found by well-known fracture mechanics tests, i.e., Charpy impact, fracture toughness, and CTOD. Hence, this study investigates the relation between FTT and DBTT in S500 high-strength steel base material and welded joints at low temperatures using fatigue crack growth, fracture toughness tests as well as scanning electron microscopy. From the tests, an almost constant decrease in fatigue crack propagation rate is determined with decreasing test temperature even below the DBTT. At −100 °C, the fatigue crack propagation rate is about half of the rate observed at room temperature for both base material and weld metal.
17
Cook, Robert F. "Crack propagation thresholds: A measure of surface energy." Journal of Materials Research 1, no. 6 (December 1986): 852–60. http://dx.doi.org/10.1557/jmr.1986.0852.
Full textAbstract:
Crack propagation thresholds in brittle materials are explained by consideration of the work done by the applied loading and that needed to create new surfaces as a crack propagates. The threshold mechanical energy release rate is shown to be a measure of the equilibrium surface energy of the material, dependent on the chemical environment. For applied loadings greater than those needed to maintain equilibrium the surface energy term introduces nonlinearities into the crack propagation characteristics. Any surface force or lattice trapping behavior at the crack tip will not influence the observed threshold provided the crack tip remains invariant on crack extension. A simple indentation/strength technique is demonstrated that permits the surface energy in the equilibrium state to be estimated. The technique is applied to the propagation of cracks in sapphire and the surface energy in water estimated as 1.42 J m−2, suggesting that the surfaces in water are stabilized by interactions stronger than van der Waals forces or hydrogen bonding alone.
18
Goanță, Viorel, Corneliu Munteanu, Sinan Müftü, Bogdan Istrate, Patricia Schwartz, Samuel Boese, Gehn Ferguson, Ciprian-Ionuț Morăraș, and Adrian Stefan. "Evaluation of the Fatigue Behavior and Failure Mechanisms of 4340 Steel Coated with WIP-C1 (Ni/CrC) by Cold Spray." Materials 15, no. 22 (November 16, 2022): 8116. http://dx.doi.org/10.3390/ma15228116.
Full textAbstract:
Fatigue behavior of standardized 4340 steel samples uniformly coated with WIP-C1 (Ni/CrC) by cold spray was investigated. In particular, when a crack appeared at the interface between the base material and the coating, the cause of it as well as its shape and size were investigated. Fatigue loading was applied by alternating symmetrical cycles. Scanning electron microscopy was used to study the onset of failure and the subsequent propagation of cracks. The interface between the two materials performed well—in all samples, the initial crack propagation occurred on the surface of the base material, continuing into the coating material and in the interior of the base material. The fatigue durability curve of stress vs. number of cycles (S-N) presented a conventional form for a metallic alloy and the coating material had an influence only on the damage on the surface of the base material.
19
Wang, Minqing, Jinhui Du, and Qun Deng. "The Mechanism of Creep during Crack Propagation of a Superalloy under Fatigue–Creep–Environment Interactions." Materials 13, no. 19 (October 4, 2020): 4418. http://dx.doi.org/10.3390/ma13194418.
Full textAbstract:
In this study, we examine the mechanism of fatigue-crack propagation in 718Plus superalloy at 704 °C under fatigue–creep–environment interactions, in this case, a new turbine disc material used in aero-engines at high temperatures. The effect of creep on the fatigue-crack propagation of the superalloy at high temperature was also researched. There was an unusual inhibitory effect on the propagation of fatigue cracks in 718Plus alloy, in which the propagation rate of fatigue cracks decreased with the increase of creep time through exploration of dwell-fatigue-crack growth (DFCG) test with different creep times. In particular, under lower stress intensity factor range (ΔK) conditions, the fatigue-crack growth rate with a 90 s hold-time was one order of magnitude lower than that with a 5 s hold-time. Conversely, the gap between the two DFCGs gradually decreased with the increase of ΔK and the creep effect became less apparent. The mechanism of crack propagation in 718Plus alloy under two creep conditions was investigated from a viewpoint of the microstructure, oxidation rate at high temperature and crack path morphology under different conditions.
20
Wang, Fei, Yu’e Ma, Yanning Guo, and Wei Huang. "Study on Thermally Induced Crack Propagation Behavior of Functionally Graded Materials Using a Modified Peridynamic Model." Advances in Materials Science and Engineering 2020 (January 25, 2020): 1–17. http://dx.doi.org/10.1155/2020/1317965.
Full textAbstract:
Peridynamic (PD) theory is used to study the thermally induced cracking behavior of functionally graded materials (FGMs). A modified thermomechanical peridynamic model is developed. The thermal crack propagation of a ceramic slab in quenching is calculated to validate the modified PD model. The results predicted by the modified PD model agree with previously published numerical and experimental ones. Compared with the original PD model, the calculation accuracy of the modified PD model for thermal cracking is improved. The thermal cracking in FGMs is also simulated. The effects of material shape, initial temperature, and ceramic fracture toughness on thermal crack propagation behaviors are studied. It can be found that the thermal cracks in FGMs are still in periodical and hierarchical forms. The metal materials in FGMs can prevent crack initiation and arrest the long cracks. The crack number tends to be increased with the increasing initial temperature, while the strengthened ceramic fracture toughness can decrease it.
21
Yang, Bing, Zhen Liao, Shoune Xiao, Guangwu Yang, Tao Zhu, and Xiangning Zhang. "Study on Short Fatigue Crack Behaviour of LZ50 Steel Under Non-Proportional Loading." Materials 13, no. 2 (January 8, 2020): 294. http://dx.doi.org/10.3390/ma13020294.
Full textAbstract:
The low cycle fatigue tests using the replica technique for LZ50 steel under non-proportional cyclic loading were carried out, and eight groups of effective test data were obtained. The evolution behaviour of short cracks was studied based on the effective short cracks criterion. The results show that short cracks generally originate in the grain or along the grain boundary. At the microstructural short crack stage, the crack propagation is influenced strongly by the microstructure of the material, and the growth rate of the short crack slows down several times according to the number of obstacles encountered. At the physical short crack stage, the crack propagation breaks through the banded structure of pearlite. Thus, the dominant effective short fatigue crack is formed, and the crack growth rate increases rapidly. Based on the modified parameters of the uniaxial short crack model, an approach is presented to calculate the growth rate of short cracks under multi-axial non-proportional loadings, and the new model can consider the non-proportional factor F. The fitting results of the multi-axial microstructural obstacles model are compared with test data. The comparison results show that this model can reflect the trend of short fatigue crack propagation rate under non-proportional loadings.
22
Sadeghipour, Keyanoush, George Baran, Hanqing Zhang, and Wei Wu. "Modeling of Fatigue Crack Propagation During Sliding Wear of Polymers." Journal of Engineering Materials and Technology 125, no. 2 (April 1, 2003): 97–106. http://dx.doi.org/10.1115/1.1543967.
Full textAbstract:
The propagation of a crack initiating at the surface was analyzed to simulate the fatigue wear behavior of glassy polymer materials. A crack in a material half plane was assumed to propagate along a predefined path as a result of contact loading by a cylinder sliding on the polymer surface. The crack path consisted of a vertical straight-line segment and a declined straight line originating at a branch point on the vertical crack segment. The stress intensity factors KI and KII along the crack path were computed by using finite element methods, and their values utilized in the Paris law to determine crack propagation rates. Because this process simulates surface pitting, component fatigue life is assumed to be proportional to the time needed for the propagating declined crack to intersect a neighboring vertical crack, a condition known to lead to pitting. This fatigue life is estimated by integrating the Paris law. Numerical results show that the branch point where the declined crack path originates can effectively hinder crack propagation, and that the rate limiting step in fatigue is crack propagation along a small segment of the declined crack near the branch point. Some important factors that affect the reliability of numerically predicted fatigue life cycles are discussed. Experimental crack propagation paths and lifetimes are shown.
23
Fageehi, Yahya Ali. "Fatigue Crack Growth Analysis with Extended Finite Element for 3D Linear Elastic Material." Metals 11, no. 3 (March 1, 2021): 397. http://dx.doi.org/10.3390/met11030397.
Full textAbstract:
This paper presents computational modeling of a crack growth path under mixed-mode loadings in linear elastic materials and investigates the influence of a hole on both fatigue crack propagation and fatigue life when subjected to constant amplitude loading conditions. Though the crack propagation is inevitable, the simulation specified the crack propagation path such that the critical structure domain was not exceeded. ANSYS Mechanical APDL 19.2 was introduced with the aid of a new feature in ANSYS: Smart Crack growth technology. It predicts the propagation direction and subsequent fatigue life for structural components using the extended finite element method (XFEM). The Paris law model was used to evaluate the mixed-mode fatigue life for both a modified four-point bending beam and a cracked plate with three holes under the linear elastic fracture mechanics (LEFM) assumption. Precise estimates of the stress intensity factors (SIFs), the trajectory of crack growth, and the fatigue life by an incremental crack propagation analysis were recorded. The findings of this analysis are confirmed in published works in terms of crack propagation trajectories under mixed-mode loading conditions.
24
Herrmann, Christoph, Daniel Schneider, Ephraim Schoof, Felix Schwab, and Britta Nestler. "Phase-Field Model for the Simulation of Brittle-Anisotropic and Ductile Crack Propagation in Composite Materials." Materials 14, no. 17 (August 30, 2021): 4956. http://dx.doi.org/10.3390/ma14174956.
Full textAbstract:
In this work, a small-strain phase-field model is presented, which is able to predict crack propagation in systems with anisotropic brittle and ductile constituents. To model the anisotropic brittle crack propagation, an anisotropic critical energy release rate is used. The brittle constituents behave linear-elastically in a transversely isotropic manner. Ductile crack growth is realised by a special crack degradation function, depending on the accumulated plastic strain, which is calculated by following the J2-plasticity theory. The mechanical jump conditions are applied in solid-solid phase transition regions. The influence of the relevant model parameters on a crack propagating through a planar brittle-ductile interface, and furthermore a crack developing in a domain with a single anisotropic brittle ellipsoid, embedded in a ductile matrix, is investigated. We demonstrate that important properties concerning the mechanical behaviour of grey cast iron, such as the favoured growth of cracks along the graphite lamellae and the tension–compression load asymmetry of the stress–strain response, are covered by the model. The behaviour is analysed on the basis of a simulation domain consisting of three differently oriented elliptical inclusions, embedded in a ductile matrix, which is subjected to tensile and compressive load. The material parameters used correspond to graphite lamellae and pearlite.
25
Hizhar, Yul, and Nusyirwan Nusyirwan. "Metode Peningkatan Ketahanan Retak Resin Polyester Terhadap Penambahan Serat Sekam Padi." Jurnal Teknik Mesin 16, no. 1 (June 1, 2023): 72–77. http://dx.doi.org/10.30630/jtm.16.1.1097.
Full textAbstract:
Polymer materials have been widely developed as alternative materials to replace metal materials due to various advantages such as having low density and an easy manufacturing process. Still, polymers have many disadvantages, including not having high mechanical strength, easy to crack when hit by impact. One of the materials studied is an unsaturated polyester polymer widely used for composite matrices in vehicle structural components, aircraft and ship bodies, and vehicle components. One of the studied fibers is rice husk particle fiber. The study of cracks is essential because it causes the material to no longer be able to support the load according to the previous plan and causes failure to occur more quickly. One way to overcome material failure due to cracks in the composite material is to prevent crack propagation by adding reinforcing material. In this study, a composite material was made using rice husk fiber to increase the crack resistance of the polyester composite matrix. From the results of crack testing, there is a tendency to increase the percentage of rice husks by 5%, 10%, 15%, and 20%. The value expected to be obtained for determining the crack resistance of the material is the value of the stress intensity factor (K1). The most significant K1 value was obtained at a 15% rice husk percentage variable of 1,558 MPa.m0.5. This price could increase the value of the pure polyester stress intensity factor K1 by 0.667 MPa.m0.5, indicating an increase of 233.58%.
26
Azinpour, Erfan, Jose Cesar de Sa, and Abel Dias dos Santos. "Micromechanically-motivated phase field approach to ductile fracture." International Journal of Damage Mechanics 30, no. 1 (August 16, 2020): 46–76. http://dx.doi.org/10.1177/1056789520948933.
Full textAbstract:
Utilization of the phase-field diffusive crack approach in prediction of crack evolution in materials containing voids is investigated herein. It has been established that the ductile failure occurs predominantly due to nucleation, growth and coalescence of micro-voids and micro-cavities, which lead to initiation and propagation of cracks till final material collapse. This study is an attempt to model the material internal degradation with the Rousselier pressure-dependent plasticity law, assisted with the phase field diffusive crack approach for the first time, in order to account for the post-critical softening regime. Such treatment requires the utilization of a damage evolution law and a crack initiation criterion which triggers the succeeding crack propagation, whereby a modified crack driving force based on the sequence of internal damage is employed. In numerical terms, the proposed model is integrated within a fully-staggered framework for the mechanical and diffusive fields and is implemented via the finite element method. The verification tests on the model is processed by several examples with the focus on both qualitative monitoring of pathological crack patterns and the quantitative analysis on the material response, particularly in the post-critical range, complemented by relevant comparisons with the existing data from literature.
27
Han, Zhichao, Caifu Qian, and Huifang Li. "Investigation of the Enhancement Interactions between Double Parallel Cracks on Fatigue Growth Behaviors." Materials 13, no. 13 (July 1, 2020): 2952. http://dx.doi.org/10.3390/ma13132952.
Full textAbstract:
In this paper, interactions of double parallel cracks were studied by performing experiments and numerical simulations. Fatigue crack propagation tests were carried out to measure crack growth rates in the specimens with double parallel cracks or a single crack. Finite element method was adopted to calculate stress intensity factors at the crack tips. Results show that the double parallel cracks at different positions present a shielding effect or enhancement effect on crack growth rates and stress intensity factors. When the double parallel cracks are offset, crack interactions mostly behave as enhancement effects. Empirical formulas were obtained to calculate the stress intensity factor at the “dangerous” crack tip of the double parallel cracks. By modifying the material parameters in Paris equation of the single crack, the double parallel cracks are simplified into a single crack with the same crack growth rates.
28
Sun, Xizhen, Fanbao Meng, Ce Zhang, Xucai Zhan, and He Jiang. "Progressive Failure and Acoustic Emission Characteristics of Red Sandstone with Different Geometry Parallel Cracks under Uniaxial Compression Loading." Advances in Materials Science and Engineering 2021 (March 11, 2021): 1–11. http://dx.doi.org/10.1155/2021/5569091.
Full textAbstract:
The geometric distribution of initial damages has a great influence on the strength and progressive failure characteristics of the fractured rock mass. Initial damages of the fractured rock were simplified as parallel cracks in different geometric distributions, and then, the progressive failure and acoustic emission (AE) characteristics of specimens under the uniaxial compression loading were analyzed. The red sandstone (brittle materials) specimens with the parallel preexisting cracks by water jet were used in the tests. The energy peak and stress attenuation induced by the energy release of crack initiation were intuitively observed in the test process. Besides, three modes of rock bridge coalescence were obtained, and wing crack was the main crack propagation mode. The wing crack and other cracks were initiated in different loading stages, which were closely related to the energy level of crack initiation. The propagation of wing crack (stable crack) consumed a large amount of energy, and then, the propagation of shear crack, secondary crack, and anti-wing crack (unstable crack) was inhibited. The relationship between the crack propagation mode and the geometric distribution of existing cracks in the specimen was revealed. Meanwhile, the strength characteristic and failure mode of fractured rock with the different geometric distributions of preexisting crack were also investigated. The energy evolution characteristics and crack propagation were also analyzed by numerical modeling (PFC2D).
29
Chen, Y. P., and J. D. Lee. "Material force for dynamic crack propagation in multiphase micromorphic materials." Theoretical and Applied Fracture Mechanics 43, no. 3 (July 2005): 335–41. http://dx.doi.org/10.1016/j.tafmec.2005.03.004.
Full text
30
Falkenberg, Rainer. "Modelling of environmentally assisted material degradation in the crack phase-field framework." Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications 233, no. 1 (March 22, 2018): 5–12. http://dx.doi.org/10.1177/1464420718761220.
Full textAbstract:
The simulation of crack propagation was conducted with a diffusive crack model in a variational framework. More, the physically sound introduction of mass transport and coupling mechanisms due to environmentally assisted effects could be realised in this framework. The objective consists of the application of the phase-field approach towards the simulation of environmentally assisted material degradation with the advantage of a non-required predefined crack path and a mesh-independent non-local formulation that facilitates the damage evolution with respect to material softening. The sharp crack is regularised by the introduction of a phase-field order parameter leading to a diffusive crack formulation. Besides the equations originating from the linear momentum balance an additional evolution equation for the crack phase-field is introduced. Furthermore, mass transport is simulated by a diffusion equation. The description delivered by the variational phase-field framework is able to simulate crack propagation according to published numerical test cases. Additionally, the calculation of stress intensity factors is possible as well as crack resistance curves that describe stable crack propagation.
31
Alrayes, Omar, Carsten Könke, and Khader M. Hamdia. "A Numerical Study of Crack Mixed Mode Model in Concrete Material Subjected to Cyclic Loading." Materials 16, no. 5 (February 25, 2023): 1916. http://dx.doi.org/10.3390/ma16051916.
Full textAbstract:
In quasi-brittle materials such as concrete, numerical methods are frequently used to simulate the crack propagation for monotonic loading. However, further research and action are required to better understand the fracture properties under cyclic loading. For this purpose, in this study, we present numerical simulations of mixed-mode crack propagation in concrete using the scaled boundary finite element method (SBFEM). The crack propagation is developed based on a cohesive crack approach combined with the thermodynamic framework of a constitutive concrete model. For validation, two benchmark crack-mode examples are modelled under monotonic and cyclic loading conditions. The numerical results are compared against the results from available publications. Our approach revealed good consistency compared to the test measurements from the literature. The damage accumulation parameter was the most influential variable on the load-displacement results. The proposed method can provide a further investigation of crack growth propagation and damage accumulation for cyclic loading within the SBFEM framework.
32
Gomez, Quriaky, Benjamin Goument, and Ioan R. Ionescu. "A Lagrangian DG-Method for Wave Propagation in a Cracked Solid with Frictional Contact Interfaces." Mathematics 10, no. 6 (March 9, 2022): 871. http://dx.doi.org/10.3390/math10060871.
Full textAbstract:
We developed a discontinuous Galerkin (DG) numerical scheme for wave propagation in elastic solids with frictional contact interfaces. This type of numerical scheme is useful in investigations of wave propagation in elastic solids with micro-cracks (cracked solid) that involve modeling the damage in brittle materials or architected meta-materials. Only processes with mild loading that do not trigger crack fracture extension or the nucleation of new fractures are considered. The main focus lies on the contact conditions at crack surfaces, including provisions for crack opening and closure and stick-and-slip with Coulomb friction. The proposed numerical algorithm uses the leapfrog scheme for the time discretization and an augmented Lagrangian algorithm to solve the associated non-linear problems. For efficient parallelization, a Galerkin discontinuous method was chosen for the space discretization. The frictional interfaces (micro-cracks), where the numerical flux is obtained by solving non-linear and non-smooth variational problems, concerns only a limited number the degrees of freedom, implying a small additional computational cost compared to classical bulk DG schemes. The numerical method was tested through two model problems with analytical solutions. The proposed Lagrangian approach of the nonlinear interfaces had excellent results (stability and high accuracy) and only required a reasonable additional amount of computational effort. To illustrate the method, we conclude with some numerical simulations on the blast propagation in a cracked material and in a meta-material designed for shock dissipation.
33
Wang, Jinnan, Yunbo Chen, Lingli Zuo, Haiyan Zhao, and Ninshu Ma. "Evaluation of Thermal Fatigue Life and Crack Morphology in Brake Discs of Low-Alloy Steel for High-Speed Trains." Materials 15, no. 19 (October 1, 2022): 6837. http://dx.doi.org/10.3390/ma15196837.
Full textAbstract:
Effective braking in high-speed trains is one of the major bottlenecks in expediting the technology and possibilities to improve speed. Although substantial progress has been made to increase operating speed, perhaps, thermal fatigue cracking in brake discs is a primary constraint so far. Thermal fatigue cracking is the major cause of brake disc failure in high-speed trains, especially trains with a speed of 350 km/h or above. In this study, new material composition is proposed for brake discs of high-speed trains. A comprehensive investigation is presented based on fatigue crack initiation and propagation, along with wear and micro-hardness characterization. Thermal fatigue tests at various thermal cycles between 20 ℃ and 700 ℃ were performed and the experimental results are compared with fatigue properties of a commercial brake disc material. An experimental trial revealed that thermal cracks normally initiate and propagate along the oxidized grain boundaries; nevertheless, crack propagation is restricted by the fine precipitates and lath structure of martensitic. Moreover, crack length at the initiation and propagation stage is predicted through crack growth rate and favorable grain size in the crack vicinity. Thermal fatigue life can be improved by dictating the microstructure and precipitate morphology of cast steel by tailoring the alloying composition.
34
Wu, Hao, and Qiuying Lu. "Analysis on the Behavior of Nonpropagating Fatigue Cracks under Steep Stress Gradients." Advances in Materials Science and Engineering 2014 (2014): 1–7. http://dx.doi.org/10.1155/2014/487410.
Full textAbstract:
A mechanism for the formation of nonpropagating fatigue cracks ahead of a notch root is presented. The stress gradients near the elongated notch root along with the propagation of short crack and the resulting nonpropagating crack lengthsanpcare estimated. The local stress which is higher than the unnotched material fatigue limitS0initiates the crack from a notch root and local steep stress gradient as a very important element leads to the nonpropagating crack. The value ofanpcdepends on the material properties, and specimen geometry as well as applied loading. The characteristic size of the short cracka0which depends on the material properties associates with the fatigue stress concentration factorKf. The estimated values ofanpcare in fairly good agreement with the experimental values available.
35
Xue, Bingshuang, Binbin Xu, Weihua Lu, and Yongxing Zhang. "Performance Review of Strain-Hardening Cementitious Composites in Structural Applications." Materials 16, no. 15 (August 4, 2023): 5474. http://dx.doi.org/10.3390/ma16155474.
Full textAbstract:
Strain-hardening cementitious composites (SHCC) are an attractive construction material with obvious advantages of large strain capacity and high strength, as well as excellent workability and easy processing using conventional equipment. Moreover, SHCC can be designed with varied mix proportions in order to satisfy various requirements and expectations to overcome the shortages of existing construction materials. However, the behavior of SHCC in the structural application is varied from that of SHCC material, which is reviewed and presented in this paper, focusing on the flexural and shear behavior of the SHCC member and the SHCC layer used for strengthening reinforced concrete (RC). The reviewed results demonstrate that both the zero-span tensile behavior of the stress concentration and the uniaxial tensile behavior of the bending effect can influence the crack propagation patterns of multiple fine cracks in the SHCC strengthening layer, in which the crack distribution within the SHCC layer is limited near the existing crack in the RC substrate member in the zero-span tensile behavior. Moreover, the crack propagation patterns of the SHCC strengthening layer are changed with varied layer thicknesses, and the SHCC strengthening layer, even with a small thickness, can significantly increase the shear load carrying capacity of the shear strengthened RC member. This work provides the foundations for promoting SHCC material in the structural application of repairing or retrofitting concrete structures.
36
Zhao, Shijun, and Qing Zhang. "Dynamic Crack Propagation and Fracture Behavior of Pre-cracked Specimens under Impact Loading by Split Hopkinson Pressure Bar." Advances in Materials Science and Engineering 2019 (June 23, 2019): 1–11. http://dx.doi.org/10.1155/2019/2383861.
Full textAbstract:
Deformation and fracture of brittle materials, especially crack propagation, have drawn wide attention in recent years. But dynamic crack propagation under impact loading was not well understood. In this paper, we experimentally tested Brazilian disk (BD) fine sandstone specimens containing pre-cracks under cyclic impact loading by the Φ 74 mm diameter split Hopkinson pressure bar (SHPB) test device. The pre-cracked specimens were named central straight through crack flattened Brazilian disk (CSCFBD). By using the low air-pressure loading conditions (0.1 MPa, equal to the impact velocity of 3.76 m/s), a series of dynamic impact tests were detected successfully, and the effects of pre-cracks on dynamic properties were analyzed. Experimental results show that the multiple cracks mostly initiate at/or near the pre-crack tips and then propagate in different paths and directions varying by inclination angles, leading to the ultimate failure. Compared to static or quasi-static loading, dynamic crack propagation and fracture behavior are obviously different. Furthermore, we characterized the crack propagation paths, directions, and fracture patterns and discussed the influences of the pre-cracks during the breakage process. We concluded that the results obtained are significant in investigating the failure mechanism and mechanical properties of brittle materials under impact loading.
37
Peng, Zeng, Shanglei Yang, Zhentao Wang, and Zihao Gao. "Fatigue Property and Small Crack Propagation Mechanism of MIG Welding Joint of 6005A-T6 Aluminum Alloy." Materials 15, no. 13 (July 4, 2022): 4698. http://dx.doi.org/10.3390/ma15134698.
Full textAbstract:
In this study, metal inert gas welding (MIG) was applied to 4 mm thick 6005A-T6 aluminum alloy welding. Compared with other parts, the hardness of the weld zone (WZ) was the lowest, about 67 HV. There was the Softening in WZ, which might make WZ the weakest zone. Then, fatigue tests were carried out on MIG welded joints. All the fatigue specimens fractured at the weld toe of the lap joint, and the fracture was characterized by a cleavage fracture. Crack closure induced by oxide was observed during the steady propagation of the fatigue crack. Impurities hindered crack propagation, changed the direction of crack propagation, and appeared in stepped fatigue strip distribution morphology; in the process of the main crack propagation, the initiation and propagation of small cracks were easily restricted and hindered by the main crack, which slowed down the propagation rate and even stopped the propagation directly.
38
Alshoaibi, Abdulnaser M., and Yahya Ali Fageehi. "Numerical Analysis of Fatigue Crack Growth Path and Life Predictions for Linear Elastic Material." Materials 13, no. 15 (July 30, 2020): 3380. http://dx.doi.org/10.3390/ma13153380.
Full textAbstract:
The main objective of this work was to present a numerical modelling of crack growth path in linear elastic materials under mixed-mode loadings, as well as to study the effect of presence of a hole on fatigue crack propagation and fatigue life in a modified compact tension specimen under constant amplitude loading condition. The ANSYS Mechanical APDL 19.2 is implemented for accurate prediction of the crack propagation paths and the associated fatigue life under constant amplitude loading conditions using a new feature in ANSYS which is the smart crack growth technique. The Paris law model has been employed for the evaluation of the mixed-mode fatigue life for the modified compact tension specimen (MCTS) with different configuration of MCTS under the linear elastic fracture mechanics (LEFM) assumption. The approach involves accurate evaluation of stress intensity factors (SIFs), path of crack growth and a fatigue life evaluation through an incremental crack extension analysis. Fatigue crack growth results indicate that the fatigue crack has always been attracted to the hole, so either it can only curve its path and propagate towards the hole, or it can only float from the hole and grow further once the hole has been lost. In terms of trajectories of crack propagation under mixed-mode load conditions, the results of this study are validated with several crack propagation experiments published in literature showing the similar observations. Accurate results of the predicted fatigue life were achieved compared to the two-dimensional data performed by other researchers.
39
Alshoaibi, Abdulnaser M. "Fatigue Crack Growth Analysis under Constant Amplitude Loading Using Finite Element Method." Materials 15, no. 8 (April 18, 2022): 2937. http://dx.doi.org/10.3390/ma15082937.
Full textAbstract:
Damage tolerant design relies on accurately predicting the growth rate and path of fatigue cracks under constant and variable amplitude loading. ANSYS Mechanical R19.2 was used to perform a numerical analysis of fatigue crack growth assuming a linear elastic and isotropic material subjected to constant amplitude loading. A novel feature termed Separating Morphing and Adaptive Remeshing Technology (SMART) was used in conjunction with the Unstructured Mesh Method (UMM) to accomplish this goal. For the modified compact tension specimen with a varied pre-crack location, the crack propagation path, stress intensity factors, and fatigue life cycles were predicted for various stress ratio values. The influence of stress ratio on fatigue life cycles and equivalent stress intensity factor was investigated for stress ratios ranging from 0 to 0.8. It was found that fatigue life and von Mises stress distribution are substantially influenced by the stress ratio. The von Mises stress decreased as the stress ratio increased, and the number of fatigue life cycles increased rapidly with the increasing stress ratio. Depending on the pre-crack position, the hole is the primary attraction for the propagation of fatigue cracks, and the crack may either curve its direction and grow towards it, or it might bypass the hole and propagate elsewhere. Experimental and numerical crack growth studies reported in the literature have validated the findings of this simulation in terms of crack propagation paths.
40
Einav, Itai. "Fracture propagation in brittle granular matter." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 463, no. 2087 (August 28, 2007): 3021–35. http://dx.doi.org/10.1098/rspa.2007.1898.
Full textAbstract:
It is nearly a century since Alan Arnold Griffith developed his energy criterion for the fracture propagation of cracks in ‘near-continuous’ solids. Needless to say that his celebrated work has revolutionized the world of material science. In a very succinct way, Griffith connected between three important aspects of the fracture process: (i) the material, (ii) the stress level, and (iii) the geometry of the crack. Nothing similar was developed for brittle granular matter, although in these materials fracture propagates in the sense of comminution. Recently, I have developed an energy theory, called breakage mechanics, based on the concept of breakage. However, the analogy between the mechanics of breakage and fracture is missing. Here I establish this relation using energy principles and derive a critical comminution pressure for brittle granular materials. This critical pressure is surprisingly complementary to Griffith's critical tensile stress for near-continuous materials. This step enables for the first time to apply the principles of fracture mechanics to all disciplines dealing with confined particles comminution such as geophysics, geology, geotechnical engineering, mineral processing, agriculture and food industry, pharmaceutics and powder technology.
41
Chang, Haijun, Mengling Shen, Xiaohua Yang, and Junxia Hou. "Uncertainty Modeling of Fatigue Crack Growth and Probabilistic Life Prediction for Welded Joints of Nuclear Stainless Steel." Materials 13, no. 14 (July 17, 2020): 3192. http://dx.doi.org/10.3390/ma13143192.
Full textAbstract:
Welded joints are widely used in the pipeline connection of nuclear power plants. Defects in these joints are an important factor leading to the failure of welded joints. It is critical to study the fatigue crack growth and life prediction methods for the welded joints with defects, to reduce their likelihood. In this paper, we present our study of the uncertainty of fatigue crack propagation and probabilistic life prediction for welded joints of nuclear stainless steel. The standard compact tension (CT) specimens were fabricated according to the American Society for Testing and Materials (ASTM) standard. Fatigue crack propagation tests with different stress ratios were performed on CT specimens, using the Mei Te Si (MTS) fatigue test system. A fatigue crack propagation rate model considering the uncertainty of material parameters, and based on the Paris formula and crack propagation experimental data, was established. A probabilistic life prediction method based on Monte Carlo simulation was developed. The fatigue crack propagation prediction result of a CT specimen was compared with the actual tested result, to verify the effectiveness of the proposed method. Finally, the method was applied to an embedded elliptical crack in welded joints of nuclear stainless steel, to predict the fatigue crack growth life and evaluate the reliability.
42
Chen, Qingfeng, Min Huang, and Jingmin Duan. "Experimental Study on the Crack Initiation and Propagation of Unequal Cracks in Rock-Like Materials." Advances in Materials Science and Engineering 2022 (October 18, 2022): 1–15. http://dx.doi.org/10.1155/2022/7697952.
Full textAbstract:
The crack in the rock is a system that coexists with multiscale and interaction cracks, and it is necessary to evaluate the deformation, stability, and strength of rock mass in many engineering projects and the failure of rock are related to the distribution of cracks in the rock. Cracks of different lengths were set in rock-like materials, and uniaxial loading experiments were carried out under 30 test conditions by changing the length of the rock bridge and the short crack as well as the crack angle. During the experiment, a high-speed camera system was used to record the failure process of the specimens. The following conclusions were obtained: when the crack angle is in the range of 30°to 60° with the loading direction, the shorter cracks are more likely to propagate and coalesce. Most of the specimens initiate cracking from the outer tip of the longer crack and the key point of crack instability is the outer tip of the longer crack. The coalescence mode of the cracks is mainly related to the length of the rock bridge length and the crack angle.
43
Gabetta, G., and L. Torri. "CRACK NUCLEATION AND PROPAGATION IN BLADE STEEL MATERIAL." Fatigue & Fracture of Engineering Materials and Structures 15, no. 11 (November 1992): 1101–11. http://dx.doi.org/10.1111/j.1460-2695.1992.tb00036.x.
Full text
44
Mukhtar, Fariha, Faisal Qayyum, Hassan Elahi, and Masood Shah. "Studying the Effect of Thermal Fatigue on Multiple Cracks Propagating in an SS316L Thin Flange on a Shaft Specimen Using a Multi-Physics Numerical Simulation Model." Strojniški vestnik – Journal of Mechanical Engineering, no. 10 (October 15, 2019): 565–73. http://dx.doi.org/10.5545/sv-jme.2019.6073.
Full textAbstract:
After more than a decade of research on thermal fatigue cracking in nuclear reactor components, the science remains incomplete. It is essential to understand the crack propagation behaviour and the influence of multiple cracks on the fatigue life of a component due to thermal fatigue load. Accurate numerical simulation modelling can help in better understanding the influence of different factors on failure propagation. In this research, a finite element-based numerical simulation model has been developed using ABAQUS commercial software to obtain insight into crack propagation and crack arrest in an SS316L thin flange on shaft specimen; the assembly is cooled internally, and cyclic thermal loading is applied on the flange rim. The experiment was carried out on a specially designed rig using an induction coil for heating the outer rim. Thermocouples were attached radially on the rim to collect detailed temperature profiles. Real-time temperature-dependent elastic-plastic material data was used for modelling. The boundary conditions and thermal profile used for the numerical model were matched with experimental data. The stresses responsible for crack initiation, the effect of crack number and crack lengths on stresses, energy absorbed at the crack tip after every thermal cycle and the threshold values of cracks are evaluated in the current work. The obtained simulation results were validated by comparing experimental observations. The developed simulation model helps in better understanding the evolution of stresses and strains in uncracked and cracked SS316L discs mounted on a flange due to thermal cycling. It also helped in better understanding the crack propagation behaviour and the evolution of energy release at crack tips. Such a model can help future researchers in designing components undergoing thermal fatigue loading, for example, in nuclear power plants.
45
Li, Xiang, Dongyang Chu, Yue Gao, and Zhanli Liu. "Numerical study on crack propagation in linear elastic multiphase composite materials using phase field method." Engineering Computations 36, no. 1 (December 3, 2018): 307–33. http://dx.doi.org/10.1108/ec-03-2018-0116.
Full textAbstract:
PurposeThe purpose of this paper is to develop an efficient numerical method to study the complex crack initiation and propagation in linear elastic multiphase composites.Design/methodology/approachA phase field method is developed to study the complex fracture behavior in multiphase composites. A damage threshold is introduced for referring crack initiation in the proposed method. The damage threshold is assigned as a material property so that different composite components possess different thresholds. In this manner, smooth transition from crack initiation to propagation is revealed.FindingsThe proposed method is used to investigate complex crack evolution in mesoscale cementitious composite, which consists of aggregates, matrix and void pores. From a mesoscale point of view, it is found that cracks prefer to evolve within the matrix phase. As a crack encounters an aggregate, it tends to bypass the aggregate and evolve along the interface. Cracks tend to avoid to penetrate through aggregates. Also, cracks tend to be attracted by void pores. From a mesoscale point of view, it is revealed that the elastic modulus and strength of concrete models are closely related to porosity.Originality/valueA criterion with a damage threshold is introduced to the proposed method. The criterions with and without a damage threshold are compared with each other in details. The proposed method is proven to be a useful tool to study mechanical behavior and crack evolution of brittle multiphase composites.
46
Solyaev, Yury. "Steady-State Crack Growth in Nanostructured Quasi-Brittle Materials Governed by Second Gradient Elastodynamics." Applied Sciences 13, no. 10 (May 22, 2023): 6333. http://dx.doi.org/10.3390/app13106333.
Full textAbstract:
The elastodynamic stress field near a crack tip propagating at a constant speed in isotropic quasi-brittle material was investigated, taking into account the strain gradient and inertia gradient effects. An asymptotic solution for a steady-state Mode-I crack was developed within the simplified strain gradient elasticity by using a representation of the general solution in terms of Lamé potentials in the moving framework. It was shown that the derived solution predicts the nonsingular stress state and smooth opening profile for the growing cracks that can be related to the presence of the fracture process zone in the micro-/nanostructured quasi-brittle materials. Note that similar asymptotic solutions have been derived previously only for Mode-III cracks (under antiplane shear loading). Thus, the aim of this study is to show the possibility of analytical assessments on the elastodynamic crack tip fields for in-plane loading within gradient theories. By using the derived solution, we also performed analysis of the angular distribution of stresses and tractions for the moderate speed of cracks. It was shown that the usage of the maximum principal stress criterion within second gradient elastodynamics allows us to describe a directional stability of Mode-I crack growth and an increase in the dynamic fracture toughness with the crack propagation speed that were observed in the experiments with quasi-brittle materials. Therefore, the possibility of the effective application of regularized solutions of strain gradient elasticity for the refined analysis of dynamic fracture processes in the quasi-brittle materials with phenomenological assessments on the cohesive zone effects is shown.
47
Li, Yue, Juhui Zhang, Zhongguo Guan, and Youliang Chen. "Experimental Study on the Correlation between Crack Width and Crack Depth of RC Beams." Materials 14, no. 20 (October 10, 2021): 5950. http://dx.doi.org/10.3390/ma14205950.
Full textAbstract:
The depth of cracks propagating inside reinforcement concrete (RC) components is barely able to be detected by visual inspection. Without any help from facilities, crack width can provide us with a proper way to explore the depth of cracks developing. Therefore, this paper tried to explore the correlation between crack width on the surface and crack depth. A static loading test was conducted on eight RC beams, considering the variation of concrete strength, cover, and reinforcement ratio. The test results indicate that concrete strength has a certain impact on cracking load and the propagation of cracks is mainly related to reinforcement ratio. The linear changes in load and crack width can be found. Originally, crack depth markedly increased with loading, but when restricted by compression zone of concrete and the height of beams, crack depth stopped extending finally. The correlation between crack width and crack depth was analyzed by studying work phases of a cross-section and experimental data. The fitting function achieved in this paper was determined to be a good agreement between the theoretical and the experimental relationship.
48
Wildeis, Anna, Hans-Jürgen Christ, and Robert Brandt. "Influence of Residual Stresses on the Crack Initiation and Short Crack Propagation in a Martensitic Spring Steel." Metals 12, no. 7 (June 24, 2022): 1085. http://dx.doi.org/10.3390/met12071085.
Full textAbstract:
The crack initiation and short crack propagation in a martensitic spring steel were investigated by means of in-situ fatigue testing. Shot peened samples as well as untreated samples were exposed to uniaxial alternating stress to analyze the impact of compressive residual stresses. The early fatigue damage started in both sample conditions with the formation of slip bands, which subsequently served as crack initiation sites. Most of the slip bands and, correspondingly, most of the short fatigue cracks initiated at or close to prior austenite grain boundaries. The observed crack density of the emerging network of short cracks increased with the number of cycles and with increasing applied stress amplitudes. Furthermore, the prior austenite grain boundaries acted as obstacles to short crack propagation in both sample conditions. Compressive residual stresses enhanced the fatigue strength, and it is assumed that this beneficial effect was due to a delayed transition from short crack propagation to long crack propagation and a shift of the crack initiation site from the sample surface to the sample interior.
49
Zhang, Yingtao, Zirong Tang, Lijuan Zhao, Benxiang Gong, Gang Wang, and Zhichao Li. "Effect of Initial Crack Position on Crack Propagation Behaviors of Heavy-Duty Transmission Gear." Materials 16, no. 17 (August 31, 2023): 5961. http://dx.doi.org/10.3390/ma16175961.
Full textAbstract:
The tooth bending fatigue fracture is caused by the alternating loads for the heavy-duty transmission gears. The crack initiation and propagation are the two major parts in the failure process. The crack propagation behavior is mainly affected by initial crack position except for the load and material properties. In this paper, the crack propagation model of a gear is established under the considering of crack initiation location by using extended finite element method (XFEM). The model accuracy is verified by testing results of strain and fractography by conducting the single-tooth bending fatigue experiment. The influence of crack initiation locations on subsequent crack propagation behavior is analyzed. The crack length in the tooth width direction and depth direction is faster when the initial crack is located in the middle of root surface. The crack growth rate is lower for the initial crack located in the surface close to the end surface of the gear.
50
Shehadeh, Mohamed, Ahmed Osman, Aly Abdelbaky Elbatran, John Steel, and Robert Reuben. "Experimental Investigation Using Acoustic Emission Technique for Quasi-Static Cracks in Steel Pipes Assessment." Machines 9, no. 4 (March 29, 2021): 73. http://dx.doi.org/10.3390/machines9040073.
Full textAbstract:
Acoustic emission (AE) is a phenomenon where transient waves of stress are generated during deformed material, which is applied to detect and monitor the cracks and cracks propagation. The majority of related literature studied simulated wave sources, which were utilized for a single point of a pipe and have been strictly controlled by temporal characteristics. Therefore, the realistic wave sources which do not have known temporal characteristics are studied in the present work. The realistic source is quasi-static crack propagation under three-point bending. The distortions of AE signals are experimentally evaluated by testing the AE signals of crack propagation using simulated sources. A variety of stress intensities are applied on a steel pipe to determine the effect of stress type and intensity on the characteristics of the source using time and frequency domains. Machines are mounted on the steel pipe to locate and reconstitute the features of time and frequency domain of the AE sources. It is concluded that the AE energy was sensitive to the crack size which was concerning to the transition of plane-stress to plane-strain. The potential of AE technique for identifying the nature, intensity and location of crack propagation is demonstrated.