High Cycle Fatigue Research Articles

Novel Creep–Fatigue Interaction Model Based on Kitagawa–Takahashi and a Probabilistic Creep Pore Model

ABSTRACTThe Kitagawa–Takahashi (KT) diagram and the El Haddad equation are widely used to predict the allowable stress range for an internal defect size . This approach discriminates between regions designating nonpropagation and propagation of short and long cracks. However, the KT diagram is incapable of describing the damage under creep conditions, as in that case, the assumption of a time‐independent threshold for fatigue crack propagation is invalid and must be considered as time dependent. The proposed Kitagawa–Takahashi with creep (KTC) method combines pore size distributions predicted by a probabilistic creep pore model with the El Haddad equation. This new approach is suitable to characterize the interaction of creep–fatigue loading. Within this work, modified Wöhler and Haigh diagrams for creep–fatigue at various temperatures are presented and validated with creep–fatigue experiments as well as high‐cycle fatigue (HCF) tests on precrept specimens made from the polycrystalline nickel‐base superalloy 247.

Characterization of Structural Steel Damage Under High-Cycle Fatigue at the Boundary of Inelastic Deformation

Characterization of Structural Steel Damage Under High-Cycle Fatigue at the Boundary of Inelastic Deformation

Crankshaft high cycle bending fatigue test method based on the combined extended Kalman filtering algorithm and different failure criterion parameters.

In this paper, an accelerated bending fatigue test method for the crankshaft was proposed based on the combination of the extended Kalman filtering algorithm method (EKF) and different failure criterion parameters. First the intrinsic frequency of the system and the fatigue crack depth were chosen to be the failure criterion parameters based on the test regulation and the theory of fracture mechanics. Then the extended Kalman filtering method was adopted in predicting the remaining high cycle fatigue life of the crankshaft during the experiment process. Finally the predicted fatigue life was selected to replace the actual test results for the key fatigue property parameter analysis. Based on this research, the time duration of the test was reduced obviously without affecting the key analysis parameters obviously. In addition, compared with the intrinsic frequency of the system, the fatigue crack depth is more suitable to be selected as the failure criterion to provide more reasonable enhancing effect. The main conclusions draw from this paper can provide some theoretical guidance for the design and manufacturing process of the part.

Mechanical behaviours of the hierarchical microstructure of PBF-LB/M 316L SS during high cycle fatigue

Mechanical behaviours of the hierarchical microstructure of PBF-LB/M 316L SS during high cycle fatigue

High-cycle fatigue and wear performance of low-carbon steel plates remanufactured with wire arc additive manufacturing

High-cycle fatigue and wear performance of low-carbon steel plates remanufactured with wire arc additive manufacturing

Probabilistic Modelling of Fatigue Behaviour of 51CrV4 Steel for Railway Parabolic Leaf Springs

The longevity of railway vehicles is an important factor in their mechanical and structural design. Fatigue is a major issue that affects the durability of railway components, and therefore, knowledge of the fatigue resistance characteristics of critical components, such as the leaf springs, must be extensively investigated. This research covers the fatigue resistance of chromium–vanadium alloy steel, usually designated as 51CrV4, from the high-cycle regime (HCF) (103–104) up to very high-cycle fatigue (VHCF) (109) under the bending loading conditions typical of leaf springs and under uniaxial tension/compression loading, respectively, for a stress ratio, Rσ, of −1. Different test frequencies were considered (23, 150, and 20,000 Hz) despite the material not exhibiting a relatively significant frequency effect. In order to create a new fatigue prediction model, two prediction models, the Basquin SN linear regression model and the Castillo–Fernandez–Cantelli (CFC) model, were evaluated. According to the analysis carried out, the CFC model provided a better prediction of the fatigue failures than the SN model, especially when outlier failure data were considered. The investigation also examined the failure modes, observing multiple cracks for higher loads and single cracks that initiated on the surface or from internal inclusions at lower loading. The present investigation aims to provide a fatigue resistance prediction model encompassing the HCF and VHCF regions for the fatigue design of railway wagon leaf springs, or even for other components made of 51CrV4 with a tempered martensitic microstructure.

Gas pore-based fatigue strength and fatigue life prediction models of laser additive manufactured Ti-6Al-4V alloy in very high cycle fatigue regime

Gas pore-based fatigue strength and fatigue life prediction models of laser additive manufactured Ti-6Al-4V alloy in very high cycle fatigue regime

High-cycle fatigue properties of hot-rolled bonding titanium-clad bimetallic steel

High-cycle fatigue properties of hot-rolled bonding titanium-clad bimetallic steel

Predicting high-cycle fatigue strength and three-dimensional fatigue crack growth in simulated compressor blade by phase-field model

Predicting high-cycle fatigue strength and three-dimensional fatigue crack growth in simulated compressor blade by phase-field model

Mechanical behavior, microstructural evolution and texture analysis of AA2024-T351 processed by multi-layer friction surfacing with high build rates

Abstract Solid-state additive manufacturing (AM) processes such as multi-layer friction surfacing (MLFS) can overcome typical disadvantages of fusion-based AM such as high residual stresses, porosity or hot cracking. The tool-less process setup of MLFS prevents contamination of the resulting components, e.g., caused by wear or the use of lubricants. The present study investigates MLFS for the precipitation-hardenable alloy AA2024-T3 using a process parameter that yields a high build rate relevant for industrial applications. The fatigue performance is shown and the microstructural and the mechanical anisotropy is examined. The fatigue properties in deposition direction show a high cycle fatigue limit of 170.5 MPa and a decrease in the maximum stress level compared to the base material due to precipitate overageing. The microstructure shows a Brass $$\{011\}\langle 211\rangle$$ { 011 } ⟨ 211 ⟩ texture at the bottom of the layers due to the application of high axial forces. In the center of the layer, no preferred texture was observed, while $$\text {B}\{\bar{1}12\}\langle 110\rangle$$ B { 1 ¯ 12 } ⟨ 110 ⟩ / $$\bar{\text {B}}\{1\bar{1}\bar{2}\}\langle \bar{1}\bar{1}0\rangle$$ B ¯ { 1 1 ¯ 2 ¯ } ⟨ 1 ¯ 1 ¯ 0 ⟩ shear textures were observed at the top part of the deposited layers. An elongated grain morphology with aspect ratios above 2 is present over the entire layer height. These microstructural characteristics cause anisotropy in mechanical properties, with highest ultimate tensile strength and elongation in deposition direction, i.e., 408 ± 5 MPa and 18 ± 3 % respectively, and the lowest values along the build direction, i.e., 377 ± 21 MPa and 9 ± 3 % respectively. The observed behavior is of considerable importance for the industrial design and application of components manufactured with MLFS as they show that MLFS can also result in anisotropic material properties, depending on the chosen process parameters. It requires careful selection of the right combination of stud material and process parameters to achieve isotropic properties in the deposited structure.

Investigations on Fatigue Life of Ball Pin After Laser Shock Peening

ABSTRACTIn the present work, laser shock peening (LSP) was applied on critical areas of ball pins made of 41CrS4 steel to extend their fatigue life. The treatment introduced compressive residual stresses up to a depth of 1 mm with maximum value of −592 MPa on the ball pin surface. This led to a suppression of fretting fatigue in the conical section of the ball pin under lower stress amplitudes and overall fatigue life improvement by a factor of 2.4. After LSP, the crack propagation speed was slowed down to 0.001 μm/cycle down from 0.1 μm/cycle. At high stress amplitudes, the location of the main fatigue crack shifted into a notched part of the ball pin. The combined effect of high stress amplitude and stress concentration changed the elastic strain dominated high cycle fatigue to plastic strain dominated low cycle fatigue where the LSP treatment had no significant impact on the fatigue life.

A Combined High and Low Cycle Fatigue Life Prediction Model for Wind Turbine Blades

A novel method is proposed for a combined high and low cycle fatigue (CCF) life prediction model based on Miner’s rule, incorporating load interactions and coupled damage effects to evaluate the fatigue life of wind turbine blades under CCF loading. The method refines the CCF damage curve by modeling the complex damage evolution process under L-H loading and establishes a life prediction model linking low cycle fatigue (LCF) and high cycle fatigue (HCF) damage curves for more accurate predictions. Compared to Miner’s rule, the M-H model, and the T-K model, the proposed approach demonstrates superior prediction accuracy, with results predominantly falling within a life factor of ±1.5. To verify the model’s practical applicability, finite element analysis (FEA) was performed on critical blade sections, reducing the prediction error to 4.3%. This method introduces a novel approach for evaluating the fatigue life of wind turbine blades with improved accuracy over existing methods.

Effects of laser shock peening on the surface integrity and fatigue properties of 34CrNiMo6 steel

Laser shock peening (LSP) is an advanced surface modification technology and is widely used for the fatigue strengthening of metallic materials. In this study, the effects of LSP on the surface structure, microhardness, residual stress, and fatigue properties of 34CrNiMo6 were experimentally investigated. The axial fatigue tests of were carried out and the S–N curves were fitted to evaluate the fatigue strength of 34CrNiMo6 specimens before and after LSP. The fatigue fractures were characterized. The results indicated that the high-cycle fatigue strength at 106 cycles increased from 417 MPa to 448 MPa after LSP treatment. The CRS formed on the surface layer of the specimen and its beneficial effect on delaying crack initiation, narrowing the fatigue striation width, reducing the crack growth rate, and enhancing the fracture toughness were the main mechanisms for improving the fatigue performance. The present study provides a reference for improving the fatigue performance of 34CrNiMo6 steel via LSP.

Novel Integrated Model Approach for High Cycle Fatigue Life and Reliability Assessment of Helicopter Flange Structures

Novel Integrated Model Approach for High Cycle Fatigue Life and Reliability Assessment of Helicopter Flange Structures

Fracture resistances of heat-treated nickel-titanium files used for minimally invasive instrumentation

BackgroundThis study compared the torsional resistance, bending stiffness, and cyclic fatigue resistances of different heat-treated NiTi files for minimally invasive instrumentation.MethodsTruNatomy (TN) and EndoRoad (ER) file systems were compared with ProTaper Gold (PG). Torsional load, distortion angle, and bending stiffness were assessed using a custom device AEndoS, and toughness was calculated using the torsional data. Cyclic fatigue resistance was evaluated using another custom device (EndoC) with 45-degree curved canal in which file was rotated until fracture using dynamic pecking motion at 37 °C. One-way analysis of variance and Duncan’s post-hoc comparison were conducted at a significance level of 95%. Scanning electron microscopy (SEM) analyzed fracture features and differential scanning calorimetry (DSC) analyzed phase transformation temperatures.ResultsER and TN showed significantly lower torsional strength than PG (p < 0.05). However, ER showed a significantly greater distortion angle and the highest toughness, followed by PG and TN (p < 0.05). Both ER and TN showed similar bending stiffness, which was lower bending stiffness than PG (p < 0.05). ER showed the highest cyclic fatigue resistance (p < 0.05). SEM revealed typical fracture features across all groups, with distinct milling grooves in PG and TN, not in ER. DSC indicated that PG and ER showed a peak of austenite (Ap) at temperatures higher than body temperature, 42 °C and 40 °C, respectively, while TN showed A p at 25 °C.ConclusionFiles for minimally invasive instrumentations typically exhibited high cyclic fatigue resistance but showed differences in the properties. The selection should depend on the root canal and tooth condition.

Assessment of Fatigue Life and Failure Criteria in Ultrasonic Testing Through Thermal Analyses

An experimental study was conducted to analyze temperature evolution during very high cycle fatigue tests. The temperature–number of cycles (T–N) curve is typically divided into three phases: Phase I—a rapid temperature increases at the start of the test, Phase II—temperature stabilization, and Phase III—a sharp temperature rise at the test’s end, coinciding with specimen fracture. The high frequencies used in ultrasonic fatigue testing can induce self-heating in specimens, but the thermal effects are not yet fully understood. Temperature is known to influence the fatigue performance of materials. To explore this, specimens were subjected to varying stress levels and intermittent loading conditions while monitoring temperature evolution using infrared thermography. The T–N curves were obtained, and S–N curves were constructed for specimens tested at room temperature. All tests were performed under fully reversed loading conditions. The experimental data were used to evaluate models commonly applied in conventional fatigue testing. Additionally, the temperature gradient at the beginning of the ultrasonic fatigue test and the heat dissipation per cycle were estimated and analyzed as potential fatigue damage parameters. These findings indicate that parameters derived from the T–N curve have significant potential for predicting very high cycle fatigue life.

Forecasting High Cycle and Very High Cycle Fatigue Through Enhanced Strain-Energy Based Fatigue Life Prediction

Abstract This study applies a novel strain-energy based fatigue life prediction method to low cycle fatigue (LCF) data additive manufactured (AM) Inconel 718 round dog-bones, specifically focusing on cycles to failure less than 105. The objective is to forecast high cycle fatigue (HCF, 106–107) and very high cycle fatigue (VHCF &amp;gt;107), aiming to approximate stress versus cycles to failure (SN) behavior and the inherent variability in the fatigue life of the material system. This tool is motivated by the need to characterize an expanding and diverse array of materials produced by additive manufacturing methods, process parameter modifications, and optimizations, which can significantly impact fatigue life and overall structural reliability. The fatigue life prediction method achieves this by generating a fatigue life distribution as a function of stress amplitude. Bayesian statistical inference and stochastic sampling techniques are employed iteratively for each test data point, incorporating stress, cycles to failure, and total strain-energy dissipated leading to fatigue failure. Experimental LCF fatigue data are acquired using a standard axial servohydraulic load frame equipped with an axial extensometer for strain and strain-energy data collection. HCF and VHCF data is generated utilizing an ultrasonic fatigue test frame capable of cycling at 20 kHz. The fatigue data obtained from both servohydraulic and ultrasonic fatigue testing are presented and compared. The energy-based fatigue life prediction framework, utilizing only LCF data, is deployed to forecast HCF and VHCF fatigue behavior for AM Inconel 718 fatigue. The HCF and VHCF data generated are then used to validate the forecasts generated from the novel energy-based fatigue life prediction method. Comparisons are made against Random Fatigue Limit curve estimations to assess the effectiveness and accuracy of the proposed methodology.

Research and engineering application of DED laser cladding repair for steam turbine XM-25 alloy LP blades

High-strength martensitic precipitation-hardening stainless steel XM-25, characterised by its high strength, high hardness, and good workability, has been utilised in engineering as the low-pressure last stage blade of steam turbines. However, it is beset by the issue of water erosion. This paper focuses on the restoration of large blade workpieces made of XM-25 material, employing directed energy deposition (DED) laser cladding with parent material powder. The parameters for laser cladding include laser power of 1300 W, movement speed of 500 mm/min, and powder feed rate of 15 g/min. The performance of the XM-25 alloy after laser cladding restoration is evaluated through non-destructive testing (PT, RT), tensile testing, hardness testing, metallographic analysis, fracture morphology analysis, residual stress measurement, and high-cycle fatigue testing. Results indicate that the material after laser cladding exhibits an ultimate tensile strength exceeding 1200 MPa, a yield strength above 1050 MPa, microhardness above 415 HBW, residual stress at approximately 30% of the base material, and a fatigue limit of 586.25 MPa – 95% higher than the base material. These findings confirm the effectiveness of the proposed DED laser cladding method for restoring XM-25 turbine blades, offering a viable engineering solution for mitigating and repairing water erosion in steam turbine components.

Large-Scale Airfield Concrete Slab Fatigue Tests

Large-scale concrete slab tests were conducted in the laboratory to evaluate the effect of multiple wheel gears on the fatigue resistance of concrete slabs. Monotonic and cyclic loading was completed on sixteen fully-supported slabs. The monotonic testing characterized the flexural strength of the concrete slab under the fullysupported conditions relative to the standard simply-supported flexural beam test. The testing program addressed the effects of peak stress ratio, stress range, and stress pulse type on the fatigue resistance of concrete slabs. For low cycle fatigue, stress range was not a significant factor while the applied peak stress controlled the number of repetitions to failure. For high cycle fatigue, peak stress and stress range affected the number of cycles to failure. An S-N curve analyses of the fatigue results showed that the number of repetitions to failure for the tridem pulses was not equivalent to the single pulse repetitions to failure for the same pulse duration, peak stress, and stress range.

Investigation of the structural performance and failure mechanisms of 3D printed continuous carbon fiber‐based composites

AbstractAdditive manufacturing of continuous fiber‐based polymeric composites has attracted global attention. This contemporary technology enables the flexibility of manufacturing customized, partially and fully functional, and advanced composite components for numerous semi‐structural and structural applications. The current study investigates the structural performance of 3D‐printed carbon fiber‐based composites in the context of tensile, flexural, and high‐cycle fatigue. The crucial S‐N curves for the unidirectional (UD) (0°) and cross‐ply (CP) (0, 90) composites have been plotted. The dominating failure mechanisms responsible for the failure of 3D printed composites under tensile, flexural, and high cycle fatigue loading at the micro‐scale have been thoroughly investigated. The influence of fiber orientation on the failure mechanisms under different structural loading has been rigorously studied. The current findings conclude that cross‐ply (0, 90) composites exhibited superior fatigue performance than the unidirectional composites when investigated at 70% of their ultimate tensile strength. The current investigation reveals that the formation of voids during 3D printing and majorly during loading is one of the leading causes of the failure of additively manufactured composites under mechanical and cyclic loads. The fiber pull‐out, fiber breakage, de‐bonding, and voids are the dominating failure mechanisms observed under tensile loading. In addition to the failure mechanisms listed under tensile loading, matrix fractures have also been observed under flexural loading. The dominating failure mechanisms differed for UD, CP (0, 90), and CP (45, −45) composites.Highlights Investigated tensile, flexural, and fatigue properties of continuous fiber 3D‐printed composites. Examined failure mechanisms under tensile, bending, and fatigue loading. Developed test coupons with built‐in tabs for tensile and fatigue testing. Cross‐ply composites showed better fatigue performance than unidirectional.