The equivalent initial flaw size (EIFS) concept was developed to provide an initial damage state for fracture mechanics-based life prediction. This study focuses on the safe fracture fatigue life prediction based on EIFS concept. A novel assessment method (M-K-T), the maximum likelihood estimation (MLE) method updated by modified Kitagawa-Takahashi (K-T) diagram method, is proposed to obtain general

This work characterizes aluminum alloy (AA) 2219 created by use of the solid-state additive friction stir-deposition (AFS-D) process. Specifically, it determines the “goodness” for use in particular circumstances of as-deposited material created by varied process parameter sets as a function of microhardness and grain size measurements. It presents ideal process parameters for AFS-D AA2219 and characterizes

In this study, fatigue behaviour of angle plies woven glass fiber reinforced polymer (GFRP) composite laminates has been investigated. Tension-tension fatigue tests were carried out under different maximum applied stresses that varied in the range of 50 - 90% of the respective ultimate strength of the laminates. Damage development in the form of debond zones and their growth was monitored. The results

In this study, small crack propagation tests are conducted on artificially defected specimens of Ti-6Al-4V under air and vacuum pressures of 100 Pa, 10-2 Pa, 10-4 Pa, and 10-6 Pa. Fracture surfaces between these environments are compared, and the effect of vacuum pressure on the crack propagation process is investigated. The similarities between surface cracks in vacuum and internal cracks in the very

High and very high cycle fatigue (VHCF) tests were performed with 17-4PH stainless steel under constant amplitude (CA) and variable amplitude (VA) loading at load ratios of –1 and 0.05. Stepwise (duplex) S–N curves were determined with failure from surface inclusions above the transition stress amplitude, σtr, and from the interior below σtr. Similar σtr for CA and VA loading were found. VA failure

Fatigue behaviors of hybrid joint, the combination of cold-formed mechanical fastening with adhesive bonding, are yet to be understood comprehensively even though they have been widely used in industries. The lack of understanding is mainly attributed to the complicated load transfer path and possible interactions between the two types of joining techniques, namely mechanical interlocking and adhesive

High cycle fatigue (HCF) at elevated temperatures is a very significant issue for superalloys commonly used in the field of gas turbine engines. However, nearly all the existing HCF S-N regression models are established irrespective of the temperature factor, which leads to the inconvenience of their application in multi-temperature HCF issues of superalloys. This paper proposes a HCF characterization

The very high cycle fatigue properties of the Ni-based single-crystal superalloy CMSX-4 coated with an MCrAlY type coating and grit-blasted were studied at 1000 °C, 20 kHz and R = -1. A recrystallized layer thicker than the size of the larger casting pores (>50 μm) drastically reduces the fatigue life without environmental influence. The recrystallized layer and roughness introduced by grit-blasting

The objective of this study was to investigate the effect of UV irradiation on the fatigue life of a bulk semi-crystalline polymer. Low-density polyethylene samples exposed to different UV irradiation doses were fatigue tested. Fatigue indicator based on dissipated energy per cycle was found to present the best correlation with the experimental fatigue results. A master curve unifying the experimental

Super-fine stainless wires (SSWs) with micron diameter and large specific surface area can simultaneously strengthen and toughen reactive powder concrete (RPC) at low volume fraction, so SSW reinforced RPC composites have potential for developing infrastructures bearing fatigue load or with aseismic requirements. In this paper, the uniaxial compressive fatigue characteristics of such composites under

Evidences have accumulated that the cyclic diffusion-induced stress within lithiation-delithiation process will result in the cyclically evolutive mechanical damage of battery electrode, which adversely affects the mechanical integrity as well as the performance of the Li-ion battery. In this work, the mechanical degradation of electrode under electrochemical-mechanical condition is innovatively evaluated

The effects of inclusion size and stress ratio (R) on the very-high-cycle fatigue (VHCF) behavior of pearlitic steel were experimentally assessed. The S–N curve under rotating bending loading exhibited a horizontal asymptote shape and a clear fatigue limit. In contrast, the S–N curve under ultrasonic axial loading exhibited a continuously descending shape, and the fatigue limit disappeared at a fatigue

For rock engineering in cold regions, rock is often subjected to coupled fatigue conditions of freeze-thaw (F-T) and stress disturbance. Rock fracture evolution and energy mechanism under room temperature and constant stress amplitude loading condition have been widely investigated. Yet the rock energy dissipation and damage evolution characteristics subjected to multiple level cyclic loading conditions

A continuum damage mechanics (CDM)-based approach is proposed to investigate fretting wear and fretting fatigue behavior of Ti-6Al-4V with the consideration of debris layer evolution. An elastic-plastic-damage model is developed to calculate the stress, strain, and fatigue damage fields. The debris layer and its thickness evolution are considered in a friction energy-based wear model. Both models are

Crack initiation, crack coalescence and small crack growth behavior were monitored for over 400 seeded inclusions during interrupted low cycle fatigue testing conducted on the P/M Udimet 720 nickel disk alloy at 650°C. Two types of seeded alumina inclusions with average sizes of 54 µm and 122 µm were used in the study performed at varying loading conditions resulting in LCF lives ranging from 2,000

Effects of build orientation (0°, 45°, and 90°) and post heat treatments (hot isostatic pressing 820° and 950°C or annealing 1020°C) on the fatigue crack growth rates (FCGRs) of Ti-6Al-4V fabricated by laser powder bed fusion were examined. Coarser α'/α lath thicknesses resulted in slower FCGRs and higher thresholds while texture and build orientation had little influence. Fatigue thresholds were defined

Turbine bladed disks normally operate under complex loadings coupling with uncertainties originate from multiple sources, including material variability, load variation and geometrical uncertainty. The influence of these uncertainties on mechanical response of engineering components are critical for their fatigue assessment and reliability evaluation. In this work, a general framework for fatigue reliability

Laser Powder Bed Fusion (L-PBF) provides ample freedom to fabricate lattice materials with tailored micro-architecture. Nevertheless, small-scale structures often suffer from a wide range of morphological defects, which impact the macro-scale mechanical properties. In this work, prominent morphological factors including geometric irregularities (surface notches and cross-section deviation), node geometry

In aerospace engineering, many additive manufacturing (AM) metal parts subject to fatigue loadings, resulting in their fatigue failure. Therefore, it is essential to develop an advanced approach for fatigue issues. Although some theoretical methods are used for fatigue analysis of AM metal parts, their implementations are time-consuming. Furthermore, these methods cannot directly consider the effects

The Indirect Tensile Asphalt Cracking Test (IDEAL-CT) is a newly developed test method that has high potential of reliably evaluating fatigue cracking of asphalt mixtures. In this study two binder fatigue testes, Linear Amplitude Sweep (LAS) and Binder Yield Energy Test (BYET), were used to measure the performance of asphalt binders. Advanced analyses on LAS/BYET data were employed to determine binder

Fatigue tests are performed on base-metal and T-joint fillet-welded specimens of EH36 high strength steel at room temperature and −40 °C. A S-N curve and a P-S-N curve with a survival probability of 97.5% are fitted to the test results. It is found that the scatter in fatigue life at low temperature is smaller than that at room temperature. The FAT values for both specimens are obtained. In comparison

In this paper Cobalt-Chromium-Molybdenum (Co-Cr-Mo) specimens produced by Selective Laser Melting (SLM) for biomedical field were studied. In particular, fatigue tests were carried out comparing as-built condition with Hot Isostatic Pressing (HIP) and a heat treatment under vacuum condition. The influence on microstructure and fatigue properties was investigated on plain specimens and with a V-notched

The characteristic far field response spectrum of welded joints – the governing fatigue sensitive locations in steel marine structures – is predominantly linear elastic, meaning mid- and high-cycle fatigue (MCF and HCF) is most important for design. Using the effective notch stress- and the total stress concept, involving respectively Se and ST as intact- and cracked geometry fatigue strength criterion

Several theories and methodologies for running effective-strain and effective-stress based crack propagation models are reviewed. Crack closure behaviour and effective crack growth rate data for various steels were collected and showed that the effective crack growth rate is independent of steel hardness and R-ratio. Crack propagation simulations on a centre elliptical notched specimen were run under

Crack closure effects are known to have a large impact on crack growth behaviour. In this work, tests were performed on Inconel 792 specimens under TMF loading conditions at 100–850 °C with extended hold times at tensile stress. The effective stress-intensity range was estimated experimentally using a compliance-based method leading to the conclusion that crack closure appears to have a primary impact

Optimizing acoustic emission (AE) is useful to understand fatigue crack growth of metal structures. Experimental investigation of fatigue in steel with an edge notch was performed using AE to understand source and location of crack formation and growth. Non-Destructive Techniques like Direct Current Potential Drop (DCPD) and Digital Image Correlation (DIC) are useful in assisting to interpret the AE

This study proposed the fatigue life prediction method for welded joints which is considered the geometric effect, the difference of cyclic stress–strain properties between parent material, the HAZ, and weld metal, and the mean stress effect by welding residual stress and fatigue loading. The proposed prediction method consists of the finiteelement analyses, which are the welding simulation and the

White etching area (WEA) has become a big challenge for bearing failure under rolling contact fatigue. Despite of the extensive investigations, the origin of the WEA has not yet been well understood. This work attempts to elucidate the origin based on a new perspective that both the WEA and the shear band (SB) can be the common responses under shear plastic deformation in bearing steel, rather than

A method combining mechanical testing, infrared thermography (IRT) and synchrotron radiation computed tomography (SRCT) is proposed for the damage evolution of 3D woven carbon/epoxy composites under tension-tension (T-T) fatigue loading. To study the relationship between the damage evolution and the stiffness degradation, fatigue tests of six specimens are carried out to different stages before detection

In the present paper, a fatigue analysis for welded joints made of mild, and high- and ultra-high-strength steel grades and post-weld-treated with grinding and combined grinding and peening methods is carried out using literature data. The 4R method was used to re-analyze the data points considering material strength, residual stress, applied stress ratio, and weld toe radius. The use of the 4R method

The influence of surface porosity on the fatigue life of additively manufactured (AMed) EH36 steel samples via selective laser melting (SLM) was studied in-depth by using a numerical method, which the pores were simulative AM 3D pores. The surface pores in both simplified semi-ellipsoid/spheroid and more realistic triangular shapes were evaluated in the first place. Stress concentration factor Kt analyzed

The asymmetrical rolling (ASR) process with shear deformation is considered as a promising technology to adjust/improve through-thickness microstructure homogeneity and integrated properties of high-strength aluminium alloy plates. But the advantages may come with caveats that are the subject of our research. In this paper, the room-temperature low cycle fatigue properties and fracture behaviour of

This study aims to understand the damage evolution of water-saturated asphalt mixture under freeze-thaw cyclic loading from the perspective of continuum damage mechanics (CDM). The connective void content of three types of asphalt mixtures was employed to characterize the damage to the corresponding asphalt mixture sample under freeze-thaw cyclic loading. The variation of connective void content revealed

In this note a new procedure is proposed for accurate determination of ΔKth and Kmax,th thresholds. This procedure does not use any assumption besides an actual crack propagation, which occurs only when both thresholds are satisfied simultaneously. These thresholds are paramount for components in service where fatigue crack initiation could cause rapid growth to failure.

This paper is a continuation of previously published work. It presents the results of small cracks observation on the surfaces of fatigued specimens subjected to multiaxial loadings. Specimens were manufactured from four materials: PA38-T6 aluminum alloy, E235 and E355 non-alloy steels, and X5CrNi18-10 austenitic steel. Based on the cracking analysis, it was found that the aluminum alloy and low-alloy

Estimation of fatigue life data which includes right censoring is challenging. The primary purpose of this paper is to incorporate right censoring into a phenomenological cumulative distribution function for fatigue life that includes a kernel that incorporates time dependent loading, mechanical breakdown, and statistical behavior. Because of its generality, the model is applicable for a variety of

Fatigue crack growth rate in Room Temperature and Out-of-Phase Thermo-Mechanical Fatigue notched specimen experiments on the nickel-base alloy IN792 is studied. It is shown that it is possible to explain the observed higher crack growth rate in OP TMF compared to RT testing for the same external load, if plasticity induced crack closure is considered. Modeling utilizes node-release finite element simulations

In this paper, the creep fatigue test at 550∼650℃ of P92 steel is carried out, which not only reveals the damage evolution mechanism, but also analyzed the creep fatigue behaviors. The influence of temperature, load holding time and pre-fatigue damage on the creep fatigue behavior of P92 steel was studied in detail. The effects of the temperature and holding time on the hysteresis loops of stress-strain

In this study, Alloy 718 specimens manufactured by Electron Beam Powder Bed Fusion process are subjected to two different post-treatments to have different microstructural features. Low cycle fatigue testing has been performed both parallel and transverse to the build direction. EB-PBF Alloy 718 exhibits anisotropic fatigue behaviour; the fatigue life is better along the parallel direction compared

In this work, the evolution of crack lengths under fatigue load is interpreted as a sample function of a cumulative damage process which, once normalized, allows a phenomenological model to be satisfactory applied using cumulative distribution functions (cdfs) of the generalized extreme value family (GEV). The denoted “retroextrapolation” procedure is used to determine the complete evolution of the

This paper presents the application of survival analysis techniques, widely used in medical research, to the development of nonlinear probabilistic S-N curves for fatigue including the effects of other covariates. The number of cycles to failure is treated as a fictitious “time-to-event” parameter. Parametric survival analyses were performed using fatigue test data for steel bridges. The loglogistic

Simulation models were constructed to explore the influence of compressive residual stress on fatigue crack growth rates in aluminium sheet. Balanced residual stress fields resulting from imposition of compressive stresses in laser peen patches were calculated. Growth rates of cracks approaching, traversing and propagating away from peen patches were calculated using modified superposition models.

This paper investigates the variability of the fatigue damage caused by the randomness of a stationary Gaussian random loading. After reviewing some methods from the literature (e.g. Madsen et al., Low), the paper presents a Monte Carlo simulation study to compare such methods with results from time- and frequency-domain analyses. Best-fitting expressions are derived to relate the variability of the

Powder metallurgy (PM) Ni-based superalloys are widely used for aeroengine turbine disc applications due to their excellent mechanical properties and good corrosion resistance at elevated temperatures. Understanding the fatigue crack growth (FCG) mechanisms of PM Ni-based superalloys is important for both disc alloy development and life prediction of disc components in these advanced aeroengines where