Laser Powder Bed Fusion and Direct Energy Deposition processes have complementary characteristics. Their hybridization can increase the variety of applications for additive manufacturing. This paper investigates the static and fatigue behaviors of hybrid Inconel 625 parts using monotonic and high cycle fatigue tests, local strain measurements and self-heating method. Fatigue properties of as-built

The titanium alloy TA15 was treated with SP (shot peening), followed by heat exposure at 500 ° C and NII (nitrogen ion implantation) treatment at 500 ° C for 5h each. The surface topography, microstructure, micro-hardness, residual stress, and fatigue behavior were, thereafter, analyzed. The results showed that the SP and NII treatments changed the surface topography of the TA15 titanium alloy, producing

Rolling bearing is a key component of machinery, its fatigue failure will affect the reliability of machinery. The bearing vibration signal has strong nonlinearity, resulting in weak fault information. Multiscale sample entropy (MSE) is an effective technique for analyzing nonlinear time series. However, MSE has limitations, such as a large deviation and weak information mining abilities, and even

Constant load amplitude and ΔK fatigue crack propagation (FCP) tests have been carried out to investigate FCP behavior of grain size transition zone in a dual microstructure turbine disc. The results show grain size exerts more significant influence in the time-dependent FCP regime, but the effect of grain size is relatively limited in the cycle-dependent FCP regime. Larger local plastic deformation

Aligned and random steel fiber reinforced cementitious composites (ASFRC, SFRC) are prepared to study how fiber orientation and volume fraction affect the fatigue life and fracture behaviors of composites. The experimental results indicate the fatigue life of ASFRC exceeds that of SFRC by more than 8 times. Compared with SFRC, the critical effective crack length of ASFRC is improved by more than 17%

Fatigue life prediction is important in engineering design to ensure structural reliability. However, it is difficult to achieve an accurate fatigue life prediction from a smooth specimen to a notched specimen with the traditional Highly Stressed Volume (HSV) method, as it is based on just one empirical evaluation of the HSV. A modified HSV method is proposed in this study, which is combined with the

A versatile data-driven model integrating domain knowledge and deep neural networks (DNNs) is proposed for fatigue life prediction with small samples. In the model, traditional fatigue life models, as comprehensive reflections of domain knowledge, are employed to generate pseudo labels for data augmentation. And a new DNN typology, called Branching neural network, is devised to distill useful training

Carbide-free bainite (CFB) steel with metastable austenite and refined microstructures has been demonstrated to be a promising alternative to conventional pearlitic rail and wheel steels, due to its outstanding static mechanical properties and performance in service. However, the exploration on its potential application in railway axles is scarce, and the effect of microstructures on the fatigue crack

The acoustic emission (AE) technique is a non-destructive real-time dynamic monitoring technique for structural health. Nonetheless, there has been a lack of research on the initiation and propagation mechanisms of fatigue cracks in rails. In this paper, the AE signal properties of fatigue crack initiation and growth are studied in three types of rail materials under different fatigue loading conditions

The fatigue behavior of woven angle ply glass fiber reinforced plastic laminates under tension–tension fatigue loading has been investigated. Rectangular specimens were subjected to fatigue loading of constant amplitude at three stress levels 80%, 70% and 60% of ultimate tensile strength for stress ratios 0.1 and 0.3. The fatigue life in woven angle ply GFRP composites was improved at all stress levels

The fatigue behavior of 41Fe-25.5Ni-23.5Cr alloy welded joints subjected to different multistage post-weld heat treatment (PWHT) conditions was studied. The fatigue life of welded joints under PWHT1 (600°C-1h/1050°C-1h/950°C-30min) was significantly prolonged, which was attributed to the low cyclic hardening rate caused by the small cyclic yielding stress and effective stress. The microstructure analysis

The acoustic black hole (ABH) effect has shown great application potential in vibration reduction, energy harvesting, etc. However, it may face the problem of structural strength due to the small thickness in local area. In this study, a frequency method based on Gaussian expansion has been proposed for fatigue analysis of ABH structure. Fatigue damage is directly estimated in the frequency domain

This paper proposes a novel approach for estimating titanium alloy structural parts’ low cycle fatigue (LCF) life based on the continuous damage mechanics (CDM) model. Using a genetic algorithm-optimized back-propagation artificial neural network (GABP-ANN), the LCF life of titanium alloy structural parts is accurately predicted. Firstly, experimental data and finite element simulation data are combined

The present work aims to study the influence of hydrogen charging on the transformation induced plasticity steel under strain-controlled low cycle fatigue (LCF). Hydrogen charging had detrimental effect on strain-controlled LCF lives. Cyclic hardening in un-charged specimen due to strain-induced martensitic transformation (SIMT) dominated over cyclic softening. In contrast, generation of large fraction

Due to the defects, the performance of laser directed energy deposition (LDED) parts was restricted. This work investigated the strain-controlled high-temperature fatigue behavior of LDED Hastelloy X after ultrasonic micro-forging treatment (UMFT). Results showed that UMFT significantly increased the fatigue life twice; mathematical statistical analysis showed that the size of the fatigue source (defect)

The notch fatigue behavior of a titanium alloy TC17 in the very high cycle fatigue (VHCF) regime is investigated by a vibration-based bending fatigue test. A complete S-N relation of notched specimens with high resonance frequencies is obtained, covering the lifetime up to 109 cycles, and the fracture surfaces are observed. The results show the TC17 exhibits relatively high fatigue notch sensitivity

In this study, an analytical model based on Hertzian contact theory and the Neuber plasticity rule is established to predict the residual stresses generated by laser shock peening (LSP). The model was validated using experimental data. A database that connects LSP parameters with residual stress can be established, and the LSP parameters that result in desirable residual stress characteristics subjected

The paper introduces the active learning Kriging (ALK) model into the structural fatigue reliability analysis. Firstly, the structural variable stress is obtained by experimental tests or finite element simulation (FES). On this basis, the cyclic stress corresponding to the fatigue life is analyzed based on the rain-flow counting method and the structural fatigue life is correspondingly computed using

Analysing the dynamic response, the fatigue failure process of aluminium alloy riveted single-shear lap joints is quantitatively described. Firstly, numerical analysis of hysteretic loops based on MATLAB is proposed, and cyclic relative displacement amplitude, stiffness and dissipated energy are calculated. Secondly, the service behaviour corresponding to the evolution of relative displacement amplitude

The influence of a proof load, or an initial overload, on the fatigue resistance of welded structures is investigated in this study. Arc welded stiffeners made of S355 steel are considered and fatigue-tested in as-welded and proof-loaded conditions. X-ray diffraction analyses are carried out to evaluate the influence of a proof load on the residual stress field. To better understand the role of a proof

This work aims to apply the Theory of Critical Distances (TCD) to the fatigue assessment of additively manufactured (AM) Ti-6Al-4V material produced via the selective laser melting (SLM) process. Modified alternatives to traditional TCD methods are considered. In this sense, it is sought to develop a fatigue prediction model that is better suited to assessing the impact of multiple stress-rising features

Gearbox power density plays a decisive role in wind energy competitiveness. As wind turbines become larger to reduce the levelized cost of energy (LCOE), bending fatigue plays a higher role in gearbox design. Shot peening (SP) has been introduced frequently as a technique to increase wind gearbox bending capacity, but other techniques, such as root grinding (RG) and superfinishing (SF), remain insufficiently

This paper studies the effect of stress lower limit on deformation characteristics of muddy sandstones during cyclic loading under pore pressure. The cyclic loading tests with pore pressure were conducted including increasing, constant, and decreasing stress lower limits. The results indicate that the relationship between deviatoric stress and volumetric strain can be divided into four cases during

The crack initiation mechanism of laser powder bed fusion (LPBF) Ti6Al4V was investigated at elevated temperature up to very high cycle fatigue (VHCF) regime. The competition concerning defect location is elaborated using the stress intensity factor range and Z-parameter model. Additionally, localized high stress near the defects is responsible for plastic strain localization in the non-prior α' region

Load interaction effects in fatigue-driven delamination in fiber-reinforced polymer composites are neglected in state-of-the-art models although this assumption highly underestimates the delamination growth under variable amplitude (VA) loading. A new phenomenon called “transient delamination growth” has recently been observed in VA fatigue experiments by the authors. In the current work a new crack

The Ottosen–Stenström–Ristinmaa (OSR) incremental fatigue damage model is adapted for fatigue-life assessment of integral airframes milled from 7050-T7451 aluminum plates. For validation, variable-amplitude high-cycle fatigue experiments are conducted for circumferentially notched, axisymmetric specimens, and for a geometry similar to an aircraft fuselage frame, with flanges, stiffeners, and web panels

Foamed polyurethane (PU) grouting materials are widely used for the non-destructive rehabilitation of roadbeds due to their expansion characteristics, lightweight, and high strength. However, their compressive fatigue resistance is still unclear. In this work, the relationships between density and strength/modulus were established by uniaxial compression tests. The fatigue damage evolution was divided

Elbow pipe components are frequently subjected to complicated thermo-mechanical load combinations cyclically in nuclear engineering, facing failures related to cyclic plastic responses, including low cycle fatigue (LCF) and ratcheting. To deal with the risk management of important pipelines, the probabilistic LCF and ratcheting assessments are indispensable to evaluate the reliability of such components

This work explores a comparative analysis to verify the applicability of the existing stress-based model to predict life under ratcheting for pearlitic rail steel. The walker model is the most accurate of the available models, but its application is limited owing to the intricacy involved and the experimental reliance on its constant (γ) assessment. As a consequence, a novel stress-based life prediction

The fatigue crack initiation at twin boundary (TB) and the life prediction of IN718 alloys in the high cycle fatigue (HCF) regime and very high cycle fatigue (VHCF) regime were investigated through crystal plasticity finite element (CPFE) simulations and experiments. The fatigue damage parameter, considering the evolution of geometrically necessary dislocation (GND) density, slip and back stress, known

Most of the micro-components, such as coronary stents, consist of an oligo-crystalline micro-structure. This means that the detection of the few coarse grains which are columnar and parallel to the longitudinal ingot axis is possible. The deformation behavior of such micro-structures is obviously different from polycrystalline materials, since the anisotropic properties of one grain, in relation to

The purpose of this paper is to investigate the effect of different diffusion-resistance bond coats on the fatigue performance of second-generation single crystal superalloys. The β-(Ni,Pt)Al coating with Re-base diffusion barrier decreased the fatigue performance of the substrate, while the γ′ coating improved the fatigue performance. Oxidation is the most important factor leading to fatigue failure

The fact that the α/β titanium alloy Ti-6Al-4V is sensitive to cold dwell loading regimes has recently been endorsed by a combination of evidence gathered from fatigue studies performed on laboratory scale specimens and the findings of a failure investigation into an in-service fan disc failure. This work confirms that Ti-6Al-4V can demonstrate dwell characteristics under fatigue loading, subject to

Short crack propagation near a coherent twin boundary in polycrystal nickel alloy is investigated with 3D crystal plasticity extended finite element modelling (CP-XFEM), utilising reconstructed experimentally characterised microstructures and crack path observations. Short 3D cracks at coherent twin boundaries are shown to grow on parallel (111) slip planes at very high rate so as to be an intrinsic

Based on the single point-group model of the maximum likelihood method, a probabilistic model consisting of the fatigue life and C(Corrosion)-S–N surface curves, and which considers the effect of pre-corrosion, is proposed and verified. It is found that in the early stage of pre-corrosion, the effect of the stress level on the life attenuation ratio is more significant than the corrosion time. Finally

This paper determines the self-healing performance and damage accumulation process of asphalt materials under different damage degrees and influence factors by the fatigue-healing-fatigue (F-H-F) time sweep test. A comprehensive index HF is proposed to characterize the fatigue-healing performance of asphalt materials. The results show that with the increase of rest time and temperature, the HF value

The fatigue damages due to pores of MIM-sintered Ti64 were investigated using the synchrotron X-ray CT imaging. The effect of pores on the fatigue strength limits was analysed independently from that of grain size by introducing the fatigue limit ratio RF. The pores near to the maximum-stress area were identified by elastic FEM. The maximum stress intensity factor KI-max at the edge of the identified

The fatigue properties of M50 bearing steel under high cycle fatigue were studied by rotating bending fatigue test at room temperature. The fatigue cracks of M50 bearing steel were primarily nucleated at MgO-Al2O3 inclusions and MC/M2C primary carbides. The voids were initiated through inclusion debonding from the matrix and primary carbide cracking under cyclic loading. Small cracks were initiated

This paper starts with a coherent description of three moment of load path-based fatigue damage parameters developed by the authors of this paper over the last decade for developing path-dependent maximum range (PDMR) multiaxial variable amplitude fatigue damage and life assessment of welded structures. These three damage parameters are respectively the zeroth moment of load path (originally called

Aeolian sand is abundant and is widely distributed in western China and thus can reduce the project cost, alleviate the consumption of river sand resources, as well as protect the ecological environment in the application of concrete. Concrete structures, such as roads, bridges, and airport runways in northern cold regions, are exposed to the combined action of freeze–thaw cycle and fatigue load, and

Acoustic Emission (AE) is used to monitor the fatigue behaviour of specimens made of aluminium alloy 7075-T6 and covered with different coating combinations: anodic oxidation (alumina) - primer layer (organic coating) - topcoat layer (organic coating)). AE monitoring allows to understand and differentiate the processes and damage mechanisms in action during fatigue for all types of specimens. The type

This paper presents the cyclic deformation behaviour and fatigue properties of a wire + arc additive manufactured Ti-6Al-4V alloy in the as built condition under strain-controlled test condition. Higher local energy input used to build the material has resulted in a coarser primary columnar β grain structure along with a coarser α microstructure compared to Ti-6Al-4V alloys produced by other additive

The local electrochemical and corrosion fatigue cracking behavior of the weld joint of Q690qE high-strength bridge steel was investigated in simulated marine environment. It reveals the weld joint was vulnerable to corrosion fatigue failure in polluted marine atmosphere with the corrosion fatigue life considerably lower than that of parent metal. The micro-galvanic corrosion effect between CGHAZ and

An online monitoring technique was developed to continuously estimate the remaining fatigue life of a padeye. Piezoceramic ultrasonic transducers were surface-mounted on the padeye for ultrasound generation and sensing. A fatigue index is defined and calculated from the experimentally measured nonlinear ultrasonic modulation components. The fatigue index is also derived as a simple power function of