Crack Initiation Research Articles

Dynamics of localized accelerated corrosion in reinforced concrete: Voids, corrosion products, and crack formation

A comprehensive 3D imaging analysis was conducted to investigate the corrosion process in reinforced concrete (RC) samples at various stages of the accelerated galvanostatic corrosion process. A state-of-the-art X-ray computed tomography (CT) scan technology was utilized to collect high-resolution 3D images of the specimen. The CT imaging was complemented and validated using a multi-faceted approach utilizing Scanning electron microscopy (SEM) and Raman spectrometry techniques. The distribution and evolution of voids, corrosion products, and cracks were investigated. A localized corrosion was observed that has some similarity to pitted corrosion but not as wide spread along the bar. The micro-scale imaging investigations revealed a gradual increase in the diameter of voids as the time of corrosion increased, especially after 8 days of accelerated corrosion process at which a significant decrease in small-sized voids (≤0.11 mm) accompanied by an increase in other void sizes was observed. At 10 and 12 days of accelerated corrosion process, the volume of larger-sized voids (≥0.35 mm) continued to increase, indicating a rapid corrosion progress and the formation of corrosion-induced cracks. In addition, a thorough X-ray CT analysis allowed us to differentiate between various categories of corrosion products. Notably, iron oxides and iron hydroxides were found to dominate the corrosion products. Understanding the composition and distribution of these corrosion products is essential as they play a significant role in the degradation and deterioration of the concrete structure. The coexistence of iron oxides and iron hydroxides in the region of corrosion products were confirmed using Raman spectroscopy analysis. The CT scan images captured the evolution of cracks at different time intervals, revealing a strong correlation between the initiation of cracks and the presence of corrosion products. Subsequently, during the cracking in the matrix, while the propagation of corrosion products within the matrix contributed to the expansion of cracks. SEM images and elemental analysis confirmed that these cracks were filled with corrosion products.

Dynamic fracture toughness and crack propagation mechanism of a heterogeneous heterostructured material under combined strengthening mechanisms

Developing fracture-resistant high-strength steels is an attractive prospect for various structural applications. In this work, a combination of carburizing heat treatment (CHT) and shot peening (SP) was used to develop combined strengthening (CS) mechanisms and to improve the mechanical strength and dynamic fracture toughness of 18CrNiMo7-6 alloy steel. Standard tensile tests and split Hopkinson pressure bar tests were conducted to investigate the strength and dynamic fracture toughness of the 18CrNiMo7-6 alloy steel. The crack initiation and propagation of samples were studied using scanning electron microscopy and transmission electron microscopy. Microstructure characterization and molecular dynamic simulations indicated that the excellent dynamic fracture toughness of the CS samples could be attributed to the grain refinement after strengthening and the formation of numerous slip bands at the crack tips, reducing the stress concentration at the crack tips. The Cr23C6 precipitates have a positive effect on the strength improvement of 18CrNiMo7-6 alloy steel. The results showed that this research can be used to guide the design of steels with high-strength and high-dynamic fracture toughness.

Fatigue life predictions for welded boiler water walls

Boiler water walls experience in-phase thermo-mechanical loading during start-ups and shut-downs, leading to low cycle fatigue (LCF) failure. This study aims at establishing an FEA-based failure prediction method for estimating the fatigue performance and service life of the welded water walls. The developed model is validated for predicting failure in the defect-free uniaxial fatigue specimens. Stress-mechanical strain hysteresis loops and accumulated inelastic strain energy density per cycle parameters are extracted from fatigue tests at 0.4%, 0.6%, and 0.7% strains. A combination of cyclic plasticity and continuous damage mechanics (CDM) theory is utilized to predict fatigue crack initiation sites and estimate the specimen fatigue life. Accumulated damage has been calculated for the life cycle of each specimen. FEA model predicted failure and service life agrees well with the experimental results. The established failure analysis parameters are then transferred from the specimen level to the water wall component level, thereby estimating the service life of defect-free water walls at 750 cycles.

Effect of limestone powder on mechanical properties of concrete based on Griffith’s microcracking theory

In order to reveal the influence mechanism of limestone powder on the mechanical properties of concrete, the manufactured sand concrete with a water-cement ratio of 0.45 was taken as the research object. The effects of different limestone powder contents (0 %, 5 %, 10 %, 15 %, and 20 %) on the compressive strength of concrete were explored based on Griffith’s microcracking theory. The nano-indentation, ultra-depth-of-field microscopy, LF NMR, and other methods were used for testing. The test results show that with the increase of limestone powder content, the elastic modulus of the Interfacial Transition Zone (ITZ) and the paste increases first and then decreases, the thickness of the ITZ decreases first and then increases, and the total porosity of the paste decreases first and then increases. The microstructure of the ITZ and the paste is the densest, corresponding to the maximum compressive strength of the concrete as the limestone content is 10 %. It is found that the thickness of ITZ can be regarded as the initial crack of concrete. The compressive strength of concrete calculated by Griffith’s microcracking theory formula is the same as the measured value. The research results provide a theoretical reference for the influence mechanism of limestone powder on the mechanical properties of concrete.

The Effect of Canal Curvature and Different Manufacturing Processes of Five Different NiTi Rotary Files on Cyclic Fatigue Resistance

Abstract Objectives The aim of this study was to evaluate the cyclic fatigue resistance of ProTaper Universal, ProTaper Next, E-FLEX EDGE, E-FLEX ONE, and ZenFlex nickel-titanium (NiTi) rotary files in 60 and 90 degrees of simulated canal curvature. Materials and Methods ProTaper Universal, ProTaper Next, E-FLEX EDGE, E-FLEX ONE, and ZenFlex were used in this study. Each system was divided into two groups testing in simulated canals with 60 and 90 degrees of curvature. Both groups were set to rotate under a controlled temperature at 37°C until fracture. The number of cycles to fracture (NCF) was recorded and two fractured files from each group were randomly selected to analyze the fractographic pattern using scanning electron microscopy (SEM). Statistical Analysis The NCF between the two groups was analyzed statistically using the Mann–Whitney U test. The statistical differences between each system at the same degree of artificial canal curvature were analyzed using the Kruskal–Wallis test. A significant difference was set at p < 0.05. Results E-FLEX ONE showed the highest mean NCF (p < 0.05) when performed in 60- and 90-degree curvatures. In addition, the file tested in a 60-degree curvature exhibited higher resistance to cyclic fatigue than the one tested in a 90-degree curvature in the mutual NiTi system (p < 0.05). The SEM micrographs exhibited a similar crack initiation area, which is the feature of cyclic fatigue failure. Conclusion E-FLEX ONE showed the greatest resistance to cyclic fatigue in both 60 and 90 degrees of curvature. This study implies that E-FLEX ONE is appropriate for severely curved canals.

Advancing the hydrogen tolerance of ultrastrong aluminum alloys via nanoprecipitate modification

Ultrastrong metallic alloys, possessing unparalleled load-bearing abilities, are coveted in many sectors, thus attracting growing research efforts. However, these alloys encounter persistent usability challenges posed by hydrogen embrittlement, which causes unpredictable fracture through crack initiation. Due to complex hydrogen-microstructure interactions and their exacerbation under high stress, advances in hydrogen resistance in ultrastrong materials are sparse throughout their long history. Herein, we report a quantum-mechanics-informed strategy for hydrogen tolerance enhancement in ultrafine-grain-hardened Al-Zn-Mg-Cu alloys, approaching their current strength limit of approximately 1 GPa. This method involves the incorporation of hydrogen-absorbing T-phase precipitates into nanograins, to substantially reduce hydrogen coverage at potential crack initiation sites. We demonstrate, via synchrotron radiation X-ray micro-/nano-tomography, scanning transmission electron microscopy and atom probe tomography, that nanoprecipitates successfully withstand shear strains exceeding 1000 and are exploitable essentials for ultra strength-hydrogen synergy, contrasting their often-assumed secondary roles in nanocrystalline alloys due to possible strain-induced dissolution, which has intuitively excluded exploring them as central elements. Our approach potentially inspires new hydrogen-resisting alloys across a broad strength-composition space.

Experimental study on the shear behaviors of inverted castellated T-steel reinforced UHPC (ICTSRU) beams with hollow section

To reduce the production costs of steel reinforced UHPC composite beams and fully utilize the material strength of steel, this paper introduced an innovative prefabricated composite beam comprising a reinforced ultra-high performance concrete beam and an internal castellated inverted T-steel, forming an inverted castellated T-steel reinforced UHPC (ICTSRU) composite beam. Investigating the shear behavior of ICTSRU beams is the primary objective of this research. Seven composite beams were loaded under simply supported four-point loading conditions, and the effects of key parameters such as the shear span-depth ratio, steel fiber volume fraction, and stirrup ratio were studied. The findings from the test indicated that the ICTSRU beams demonstrated superior deformation ability and significant residual shear strength after the peak load. The shear span-to-depth ratio significantly influenced the failure modes and carrying capacity of the ITSRU beams. As the span-to-depth ratio increased from 1.1 to 1.6 and 2.1, the failure mode developed from shear failure to flexural failure and the shear resistance decreased by 19 % and 48 %, respectively. Enhancing the steel fiber volume fraction and the stirrup ratio can mitigate the initiation and propagation of diagonal cracks, thereby augmenting the shear strength and ductility of ICTSRU beams. Following a comprehensive analysis of the experimental results, a predictive model for the shear strength of the ICTSRU beam is proposed. This model posits that the shear capacity of the ICTSRU beam comprises the shear resistance contributions from the UHPC matrix, stirrups, steel web, and steel fibers. A comparative analysis of the computed values and the test results showed that the proposed calculation method has a high accuracy in predicting the ultimate shear strength of ICTSRU beams.

A data‐assisted physics‐informed neural network (DA‐PINN) for fretting fatigue lifetime prediction

AbstractIn this study, we present for the first time the application of physics‐informed neural network (PINN) to fretting fatigue problems. Although PINN has recently been applied to pure fatigue lifetime prediction, it has not yet been explored in the case of fretting fatigue. We propose a data‐assisted PINN (DA‐PINN) for predicting fretting fatigue crack initiation lifetime. Unlike traditional PINN that solves partial differential equations for specific problems, DA‐PINN combines experimental or numerical data with physics equations as part of the loss function to enhance prediction accuracy. The DA‐PINN method, employed in this study, consists of two main steps. First, damage parameters are obtained from the finite element method by using critical plane method, which generates a data set used to train an artificial neural network (ANN) for predicting damage parameters in other cases. Second, the predicted damage parameters are combined with the experimental parameters to form the input data set for the DA‐PINN models, which predict fretting fatigue lifetime. The results demonstrate that DA‐PINN outperforms ANN in terms of prediction accuracy and eliminates the need for high computational costs once the damage parameter data set is constructed. Additionally, the choice of loss‐function methods in DA‐PINN models plays a crucial role in determining its performance.

Analysis of failure properties of red sandstone with structural plane subjected to true triaxial stress paths

In order to study the mechanical behavior and failure characteristics of rock mass with the structural plane in complex deep stress environment, the QKX-YB200 true triaxial rockburst test system, acoustic emission, and digital video recorder were adopted to conduct true triaxial loading and unloading indoor tests on the red sandstone cube specimens. The results show that: (1) Under true triaxial loading conditions, all specimens propagate in the form of anti-wing crack, and the dip angle of the structural plane is linearly related to the average value of the anti-wing crack propagation angle; under true triaxial unloading conditions, the specimens with structural plane dip angles of 30°, 45°, and 60° propagate in the form of wing crack, while those with a 90° angle propagate anti-wing cracks, and the closure of structural plane is related to the the crack type at the tips of structural plane. (2) The unstable failure stages in the stress–strain curve under true triaxial unloading are longer and exhibit more pronounced fluctuations; the peak strength of the specimens under the conditions of true triaxial loading and unloading decrease first and then increase with the increase of the dip angle, reaching the lowest at 45°. (3) During the true triaxial unloading tests, the rockburst degree of the intact rock specimens is more violent than that of the specimens with a structural plane. Additionally, the dip angle of the structural plane influences the severity of rockbursts under the same stress path. (4) The crack propagation mechanism and the closure degree of structural planes under different true triaxial stress paths and dip angles are discussed. It is observed that the crack initiation mode around the structural plane tips and the crack mode near free surface are closely related to the stress environment in different areas of the specimens. (5) Based on the indoor test results and previous experimental data, the differences in peak strength characteristics between open structural planes and closed structural planes are preliminarily analyzed and compared.

Flexural behavior of concrete reinforced with micro basalt fibers and BFRP minibars

The use of basalt fibers as the reinforcement for concrete is an effective and eco-friendly solution to improve the ductile behavior and flexural toughness. For this purpose, an experimental investigation was conducted, where the concrete reinforced with micro basalt fibers or BFRP minibars were adopted. The morphologies of micro basalt fibers, straight, twisted and crimped BFRP minibars were analyzed for optimal enhancement effect. Also, the fiber length of 20 mm, 35 mm and 50 mm and fiber volume fraction of 0.5 %, 1 %, 2 % and 3 % were investigated. In addition, stiffer steel and softer polypropylene fibers were introduced to evaluate the effect of fiber modulus on concrete properties. The failure modes, load-deflection curves, fracture energy, flexural toughness and factor analysis were illustrated. The results show that the addition of micro basalt fibers with fiber lengths of 50 mm and volume fraction of 1 % increased the initial cracking strength by 28.8 %. Concrete reinforced with BFRP minibars with 50 mm in length and 1 % in volume fraction, has a flexural toughness ratio of 99.0 % of commercial steel fibers and a flexural toughness index (I5) of 113 % of commercial steel fibers. Based on the parametric analysis, the optimum length of BFRP minibars was 35 mm and the optimum fiber volume fraction was not more than 2 %. The prediction model for stress deflection response with high precision was proposed with regression coefficients ranging from 0.909 to 0.988. It was concluded that micro basalt fibers prevented the generation of microcracks through the bridging effect, whereas macrocracks and deep source cracks generated after concrete cracking were inhibited by BFRP minibars. The understanding of what exactly constitutes an optimal selection of fibers capable of producing maximum flexural properties of concrete was of great significance in engineering applications.

Observation and modeling of potential sub-threshold damage growth mechanism for nitinol in ultra-high cycle fatigue

Fatigue fracture of small nitinol components commonly used in medical devices is currently dominated by the initiation and/or growth of small cracks at non-metallic inclusions preceding conventional fatigue crack growth. Therefore, an understanding of the threshold and growth of small cracks is critical to inform fatigue performance of devices. In this paper, we conduct rotary bend fatigue experiments of nitinol wire to 2 billion cycles, measure the inclusion from which the crack initiated, and calculate the stress intensity threshold. Inclusion size is compared to the size of a unique feature observable with a scanning electron microscope which appears as a smooth area surrounding the inclusion and only on specimens that fractured after > 10 million cycles. The hypothesis presented is that the smooth feature around the inclusion is the growth of a small crack which continues until it reaches a size large enough to cause conventional fatigue crack growth. Relating inclusion size to that of the smooth feature creates a damage curve that can be written as a function of cycles to fracture. This damage curve may be useful to estimate the critical size of the largest allowable defect based on the design life and applied loading of the nitinol component.

Flexural Behaviour of Reinforced Shotcrete beams Comprehending Waste Plastic Fiber

Abstract Wet-mix shotcrete is often used as a placement method in tunnelling and ground support. However, to date, only a limited number of studies have been identified the roles of waste plastic fiber (WPF) on wet-mix shotcrete mixtures. This experimental study show the flexural performance of reinforced shotcrete concrete members (beams) having waste plastic fiber, which may be considered as a new study. In order to achieve that, a manufacturing of wet-mix shotcrete machine has been developed to product special wet-mix shotcrete that will be used to cast reinforced shotcrete concrete members containing waste plastic fiber. Extensive attempts were done in this project to generate a special wet-mix shotcrete combinations using locally sourced waste materials like beverage bottles. The qualities of WPF shotcrete concrete (SC) were investigated in terms of fresh, hardened, mechanical, and bending behaviour, with extensive results analysis. Five SC formulations (0.25, 0.5, 0.75, 1.0, and 1.25) percent WPF content, as well as the control shotcrete (SC0.00), were used in the experiments. In addition, the flexural behaviour of SC beams casted from the same waste materials was investigated. The results revealed that all SC beams had almost similar flexural behaviour when compared to the creation of crack patterns, as well as the ductility index and stiffness. The maximum ductility index was 2.29 for SC0.25, while the minimum stiffness was 1.31 for SC 1.25 beam. The flexural resistance of SC beams show in beams deflection state, the primary crack with presence the waste plastic fibers was small, because of the resistance of plastic fibers to tensile stresses happening at a moment of growth the crack. It also shows that adding WPFs to SC up to (Vf=1%) results in a rise in the loads that cause initial cracks when compared to beams made with reference mix.

Effect of over-ageing on the tensile and torsional fatigue properties of the AlSi7Cu0.5 Mg0.3 precipitation-hardened cast aluminium alloy

The objective of this work is to evaluate the influence of over-ageing on the high cycle fatigue behaviour of the AlSi7Cu0.5Mg0.3 cast aluminium alloy. It is generally accepted that over-ageing has a large influence on the behaviour of these materials, however its effect on the fatigue strength is less understood. This work provides an experimental investigation of the effect of over-ageing on high cycle fatigue strength in both tensile and torsional loading conditions. It is shown that the torsional fatigue strength is more sensitive to over-ageing when compared to the tensile fatigue strength and that the fatigue defect sensitivity is negligible for torsional loads, in contrast to tensile loading conditions. The experimental results indicate that this is due to a change in the crack initiation mechanism, going from initiation in the matrix for torsion loads to initiation from casting defects for tensile loads. An original two-steps approach is proposed to rationalise the effect of over-ageing on the fatigue strength, with particular emphasis on decoupling the respective contributions from defects and the mechanical properties. This approach is used to build normalised Kitagawa-Takahashi diagrams that highlights the reduced defect sensitivity under tensile loads for the most severe over-ageing condition.

Investigation of failure analysis on fatigue crack initiation influenced by critical resolved shear stress in X10CrMoVNb9-1 steel

This study investigates the influences of the critical resolved shear stress (CRSS) values on calculating the number of cycles for the fatigue crack initiation cycle of X10CrMoVNb9-1 (P91) under cyclic loading conditions at room temperature while considering varied surface roughness on microstructure models. The micropillar compression test was utilized to calculate the CRSS values, incorporating the Schmid factor, the Frank–Read source together with the Hall–Petch effect, measuring the diameter of the micropillar after compression, and the Mlikota and Schmauder equation. Two primary microstructure surface roughness – plane surface roughness (PS) and surface roughness (SR) with an average of 1 µm – were generated using the Voronoi Tessellation (VT) method. Finite Element Method (FEM) simulations were conducted to identify different stress distributions across these artificial microstructures. These stress distributions were subsequently analyzed using the physics-based Tanaka-Mura model (TMM) to estimate the number of cycles for fatigue crack initiation at several stress amplitudes and six types of microstructure. The number of cycles varies significantly at lower stress amplitudes and convergence at higher stress amplitudes. The study of the CRSS of steel P91 offers a significant advancement in fatigue research, particularly with implications for power plants.

Exploring microcrack formation in cyclic and dwell fatigue in MTR-lean Ti 6242 alloy

This study examines cyclic and dwell fatigue crack initiation and growth in well forged, low microtexture intensity Ti 6242 alloy. The statistics of crack occurrence have been explored in cross-sections of samples that failed in cyclic and dwell fatigue. Cracks are observed dominantly on the basal planes of the primary α grains with a high Schmid factor for basal slip in both cyclic and dwell fatigue and also in hard α grains in dwell fatigue. The crystallography of early crack initiation and extension is described. Electron channelling contrast imaging shows that basal slip dominates low strain behaviour in this alloy, leading to the observed crack formation.

Fatigue crack growth rate under mixed-mode loading conditions (I+III) of a carbide-free bainitic steel designed for rail applications

Carbide-free bainitic steel was designed for railway infrastructure application, focusing on high-speed and heavy-loaded freight tracks. Considering the complex state of stresses occurring on the rails running surface, mode III plays a significant role in the initiation and propagation of fatigue cracks of rails during service. Thus, the Fatigue Crack Growth Rate (FCGR) under mixed-mode loading conditions (I+III) was evaluated. It was revealed, that fatigue lifetime increases with loading angle modes. In the area of fatigue fracture, transgranular cracking mechanisms dominated. For the stable fatigue crack growth, a trend was observed related to the decrease in the fraction of intergranular fracture with the increasing loading angle modes (α). Secondary cracks indicated privileged cracking directions related to the crystallographic structure of bainite. The influence of the mechanical stability of retained austenite during mixed-mode FCGR requires further in-depth research. These studies contribute to understanding the factors influencing the reliability of railway tracks in terms of designing new materials and modeling the rate of crack growth to precise assessment of the life cycle of rails.

Hybrid finite element modeling of subsurface-originated spalling in flexible bearings with hoop stresses

The flexible bearing in a harmonic reducer undergoes structural deformation after being mounted on the cam, causing the bearing to operate under a complex stress state. A hybrid finite element model is developed to investigate crack initiation and propagation in flexible bearings with hoop stress under rolling contact fatigue loading. The model is coupled with continuum damage mechanics, and the damage evolution equation takes the maximum shear stress amplitude as the damage-causing stress since the hoop stress inevitably affects the fatigue life. The model is verified by comparison with the fatigue life of the inner ring without hoop stress. The crack initiation and spalling formation mechanisms in the inner ring assembled with the cam are analyzed in detail. Moreover, the effects of contact load and equivalent interference on the inner ring’s spalling morphology and fatigue life are studied.

Compression-induced failure characteristics of brittle flawed rocks: Mechanical confinement-dependency

The flaw tips in brittle rocks are often the sources of crack initiation and growth due to the stress concentration, which commonly governs the rock strength. However, a unified framework identifying the compression-induced crack types, ultimate failure patterns and the cracking levels of brittle flawed rocks under different mechanical confinements is not yet available. This study conducts the laboratory compression experiments with the AE monitoring to explore the failure characteristics of flawed limestone and its confinement-dependency. Four new crack types including loop crack, secondary transverse crack, near-field transverse crack and far-field transverse crack are found experimentally, and then a modified crack type classification strategy is proposed. Four failure patterns including the σ1-axisymmetric flaw-disturbed spalling for uniaxial compression, the σ3-transverse-symmetric flaw-disturbed spalling for biaxial compression, the σ1 −axisymmetric flaw-disturbed shearing for conventional triaxial compression, and the mixed σ3-transverse-symmetric flaw-disturbed shearing and σ2-transverse-symmetric flaw-disturbed spalling for true triaxial compression, are documented for the first time. Moreover, an acousto-mechanics-based classification methodology of rock cracking levels is established, as well as an AF (average frequency)-RA (rising angle)-based Kernel density estimation method for interpreting the rock cracking nature and the strength mechanism. This paper gets insights into the mechanical confinement-dependency of the rock failure characteristics incorporating the pre-existing flaws and help interpret the field observations.

Effect of chemical etching time on the fatigue behavior of Ti‐6Al‐4V produced by laser powder bed fusion

AbstractThis study focuses on the evolution of the fatigue strength of Laser Powder Bed Fusion (L‐PBF) produced Ti‐6Al‐4V as a function of the chemical etching finishing process. The aim is to identify the critical fatigue crack initiation mechanisms and the transitions between them in terms of the evolution of the surface micro‐geometry. This is done using three different geometries and six different surface states. The evolution of the crack initiation mechanisms is then used to explain the evolutions of the fatigue strength and the fatigue scatter. Chemical etching affects the fatigue life via a polishing effect, which directly influences both the finite and the high cycle fatigue domains. It is shown that chemical etching makes it possible to obtain fatigue strengths that are almost similar to those of the machined surface. However, it is also observed that etching cannot fully counteract the effects of large surface cavities caused by surface connected porosities.

Sensitivity Analysis of Fatigue Life for Cracked Carbon-Fiber Structures Based on Surrogate Sampling and Kriging Model under Distribution Parameter Uncertainty

The quality and reliability of wind turbine blades, as core components of wind turbines, are crucial for the operational safety of the entire system. Carbon fiber is the primary material for wind turbine blades. However, during the manufacturing process, manual intervention inevitably introduces minor defects, which can lead to crack propagation under complex working conditions. Due to limited understanding and measurement capabilities of the input variables of structural systems, the distribution parameters of these variables often exhibit uncertainty. Therefore, it is essential to assess the impact of distribution parameter uncertainty on the fatigue performance of carbon-fiber structures with initial cracks and quickly identify the key distribution parameters affecting their reliability through global sensitivity analysis. This paper proposes a sensitivity analysis method based on surrogate sampling and the Kriging model to address the computational challenges and engineering application difficulties in distribution parameter sensitivity analysis. First, fatigue tests were conducted on carbon-fiber structures with initial cracks to study the dispersion of their fatigue life under different initial crack lengths. Next, based on the Hashin fatigue failure criterion, a simulation analysis method for the fatigue cumulative damage life of cracked carbon-fiber structures was proposed. By introducing uncertainty parameters into the simulation model, a training sample set was obtained, and a Kriging model describing the relationship between distribution parameters and fatigue life was established. Finally, an efficient input variable sampling method using the surrogate sampling probability density function was introduced, and a Sobol sensitivity analysis method based on surrogate sampling and the Kriging model was proposed. The results show that this method significantly reduces the computational burden of distribution parameter sensitivity analysis while ensuring computational accuracy.