Reduction In Fatigue Life Research Articles

Experimental investigation on the fatigue life and damage mechanism of plain weave composites under biaxial tension–torsion combined fatigue loading

In this paper, the fatigue life and damage mechanism of plain weave composites under biaxial tension–torsion combined fatigue loading (TTF) are experimentally investigated. A biaxial TTF loading spectrum is designed to consider different fatigue frequencies and amplitudes, and an automated multi-module loading method with synchronized acquisition of the digital image correlation (DIC) and the testing machine is proposed. A comprehensive analysis of the experimental results, including fatigue lives, strain distribution, temperature variation, stiffness degradation, and typical damage morphologies at different fatigue cycles, has been conducted by utilizing DIC, infrared thermography (IRT) and computed tomography (CT). It is observed that the superimposed torsional fatigue load results in a rapid reduction in fatigue lives of plain weave composites, accompanied by more significant residual strain, energy dissipation, temperature rise and stiffness degradation. Particularly, the superimposed torsional fatigue loads mainly promote matrix cracking and debonding around the fiber/matrix interfaces, which then accelerates the damage initiations and accumulations of fiber yarns, ultimately leading to a rapid reduction in TTF fatigue lives. This study can provide valuable references for the design and safe application of plain weave composites under TTF loading.

Fracturing pump head body failure analysis and improvement measures

The head body of fracturing pump is one of the most easily damaged parts in fracturing equipment. Due to its own structure and working environment, it is easy to cause stress concentration, fatigue cracking and other problems. The working time of a batch of fracturing pump head body used in an oilfield is more than 300 h, and the pump head body is designed by the manufacturer for the oilfield.In this paper, the five-cylinder fracturing pump head body of this batch of cracking occurred as the research object. Firstly, the macro fracture analysis, physical and chemical properties analysis and micro fracture analysis were carried out at the cracking place. Secondly, the finite element analysis and fatigue life analysis were carried out by using ANSYS Workbench software and nCode software to explore the cause of pump head cracking failure. The results show that the crack originates from the sharp corner of the outer corner and spreads to the inner cavity. The chemical composition and mechanical properties of the pump head meet the requirements of the technical agreement. The grain size of the material does not meet the requirements of the technical agreement. The primary fracture morphology observed is indicative of fatigue streaking, while stress concentration can be identified at the location of this crack. There are two reasons for the cracking. First, the structure design is unreasonable and there is a large stress concentration at the cracking location. Second, the grain size of the material is large, resulting in a significant reduction in fatigue life, which is mainly related to the chemical composition of the material, forging process and heat treatment process, and ultimately lead to the pump head body cracking at the outside right Angle shoulder, expanding to the inner cavity, and cracking. According to the analysis results, the improvement measures of pump head body can improve the stress distribution and relieve fatigue. The results can provide a reference for the structural design and optimization of the pump head body.

Fatigue failure behaviour of bolted joining of carbon fibre reinforced polymers to titanium alloy

Carbon fibre reinforced polymers are widely used in industry, the problem of joining them with metal materials becomes significant. This is because of the loosening of bolted joints under applied loads, leading to a rapid reduction in fatigue life and even structural failure accidents. This study focuses on fatigue failure mechanisms of bolted joints of carbon fibre reinforced polymers to titanium alloy and looking for a novel solution to improve the fatigue life of bolted joints. Firstly, fatigue life prediction of the components is conducted based on FE-SAFE. Then, experiments are conducted to verify simulation results. Finally, the thread damage and the fracture morphology are analysed after tests. It is found that the fatigue life of bolted joints can be improved by increasing the stiffness of connected parts and choosing appropriate geometric parameters.

Fatigue Life Prediction and Verification of Railway Fastener Clip Based on Critical Plane Method

Accurately predicting the fatigue life of fastener clips is crucial for improving material processing technology, enhancing the anti-fatigue design level, and guiding the maintenance and repair of track structures. Conventional methods that solely evaluate the fatigue life of fastener clips based on the uniaxial stress index under displacement loads may lead to significant errors. In this paper, the stress field of a type-III clip under displacement loading conditions was numerically simulated based on fatigue test standards, and the fatigue life of the clip was analyzed using the Fatemi–Socie (FS) multiaxial fatigue criterion based on the critical plane method. A comparison with standard fatigue test results revealed that, under non-resonance conditions, the predicted position of the fatigue critical plane of the fastener clip coincided with the fracture surface observed at the middle of the measured small arc, with a life prediction error of 7.3%. To further investigate the predictive capability of the FS multiaxial fatigue criterion for the fatigue life of the fastener clip under resonance conditions, the stress levels of the clip under non-resonance and resonance conditions were compared through on-site testing, and the effects of inertial loads caused by vertical and lateral vibration acceleration on the stress field of the clip were analyzed in numerical simulation according to the results of clip acceleration tests; the fastener clip’s resonance fracture position and fatigue life were also predicted based on the aforementioned multiaxial fatigue criterion. To verify the accuracy of the predicted results, a testing method was proposed that equates the high-frequency resonant inertial load of the fastener clip to a low-frequency additional preload under the premise of consistent stress fields. A comparison with the numerical simulation results shows that considering only vertical inertial loads would result in a discrepancy between the measured fracture location and the actual one. Considering both vertical and lateral inertial loads, the fracture location (at the heel of the small arc) under resonance conditions could be accurately determined, with a life prediction error of 13.8%. Compared to the non-resonant displacement loading condition, the inertial loads caused by acceleration under resonance conditions led to a reduction in fatigue life of approximately 77.8%.

High cycle fatigue life estimation of punched and trimmed specimens considering residual stresses and surface roughness

Shear cutting processes have a detrimental effect on fatigue of high strength metal components. The effect tends to increase with material grade, counteracting the task of reducing weight in chassis components using higher strength materials. Base material fatigue data are often available, but assessment of components with cut edges often require additional costly and time-consuming testing. This paper provides a methodology for estimation of fatigue life reduction by using residual stresses obtained from process simulations, and measured surface roughness in the cut edge. A stress relaxation criterion is applied to handle reduction of the initial local residual stresses. Two complex phase steels and one aluminum alloy are studied for validating the approach. Polished fatigue data is reduced to estimate S–N curves of trimmed and punched specimens at different load ratios. Good agreement between the model and test results are found for all cases. The needed data for the predictions are only a high cycle S–N relationship for polished material, uniaxial tensile properties, and the cut edge fracture surface residual stress and roughness without any parameter fitting, making it a convenient tool for estimating the reduction in fatigue life and for parameter studies.

Microstructure, microhardness, tensile and fatigue investigation on laser shock peened Ti6Al4V manufactured by high layer thickness directed energy deposition additive manufacturing

Thin layer thickness in additive manufacturing (AM) has always been a hindering factor leading to long completion times. Increasing layer thickness is accompanied by a higher tendency of surface cracks and inferior mechanical properties. These can be improved with laser shock peening (LSP). Emphasizing on the high layer thickness, this paper elucidates the high-layer thickness laser directed energy deposition (LDED) AM and the effects of LSP on the fabricated parts. Primary focus was given to the investigation of surface microcracks, microstructures, tensile and fatigue properties. Ti6Al4V bulk sample was prepared using the LDED process. Tensile, fatigue, and other samples were extracted to investigate the above-mentioned properties using different characterization tools such as optical microscope, scanning electron microscope, Vickers microhardness tester, and universal testing machine. Results showed proper depositions without major defects despite the high-layer thickness. Micro-cracks were limited to the surface only, and typical Widmanstätten patterns with parallel α lath and mixed α+β microstructures are observed. Yield strength (YS) varied from 730 MPa to 940 MPa, while ultimate tensile strength (UTS) ranged from 799.5 MPa to 953.75 MPa. Even though laser peening significantly improved micro-hardness by 49.81 % on average, not all fatigue samples observed enhanced fatigue life. A maximum improvement of 40.34 % in fatigue performance was observed in the LDED+LSPed samples. The strain hardening, plastic deformation, and grain refinement during the LSP process contributed to the enhanced mechanical properties. Some samples’ reduced fatigue life may be due to the anisotropic nature of additively manufactured parts, internal defects, and surface cracks on the specific samples. Considering high layer thickness, vertical orientation of samples, and as-prepared samples, our research shows a promising high layer thickness additive manufacturing process. The current research can be used as a base for further study on other properties and characteristics.

Effect of aging state on low cycle fatigue performance of AA 2099 alloy

The evaluation of the fatigue performance is a crucial subject in the research of structural materials utilized in the field of aerospace engineering. In order to examine the influence of aging state on fatigue performance, low cycle fatigue (LCF) experiments were conducted on specimens made from AA2099 alloy in the under-aged (UA), peak-aged (PA), and over-aged (OA) states, with varying strain amplitudes (Δεt/2=0.3 %-0.5 %). In the UA and PA states, the grain boundary precipitates exhibit a small size, thereby prompting the crack to propagate through the grains. Certain grains in this region exhibit a crystallographic feature of crack propagation along the (111) slip plane, which is associated with the formation of the precipitation free bands (T1-PFB) within the grains. In contrast, in the OA state, the size of the grain boundary precipitates increases significantly, accompanied by a minimum precipitation free zones (PFZs) width increase to 75 nm, exacerbating the stress concentration at grain boundaries, with cracks primarily extending along the grain boundaries. Furthermore, the presence of coarse grain boundary precipitates and the widened PFZs promote the initiation and propagation of fatigue cracks, leading to a pronounced reduction in fatigue life.

Fatigue response of multiscale extrusion-based additively manufactured acrylonitrile butadiene styrene-graphene nanoplatelets composites

This study investigates the effect of varying concentrations of graphene nanoplatelets (GNPs) on the mechanical and fatigue characteristics of acrylonitrile butadiene styrene (ABS)/GNPs nanocomposites, both in filament form and as 3D-printed parts with different raster orientations. Quasi-static and cyclic loading tests were performed on specimens containing 0.1 wt%, 0.5 wt%, 1.0 wt%, and 2.0 wt% GNPs. The results indicated that the addition of 0.1 wt% GNPs to the ABS polymer matrix increased the ultimate tensile strength (UTS) of the filament by 18 %. Addition of 1.0 wt% and 2.0 wt% GNPs to the matrix improved the Young's modulus of the filament by up to about 35 % but did not enhance the UTS. The filament containing 0.5 wt% GNPs demonstrated the highest fatigue life, even higher than that of the standard samples fabricated through injection molding technique. This was due to its high static strength, Young's modulus, and ductility. However, when the ABS/GNPs nanocomposites were 3D-printed, the addition of GNPs had no major impact on their fatigue life, especially in the higher load levels. Inadequate adhesion and reduced interlayer bonding strength resulted in a detrimental impact on fatigue life of 3D-printed objects. The extrudate-swell phenomenon seems to significantly affect this reduction in fatigue life. To address this, larger nozzle diameter (0.6 mm) was used in fabricating 3D-printed samples. Results indicated that samples with less distortion and smaller extrudate-swell had higher fatigue life. It highlights the importance of considering GNP concentration and printing parameters for optimal fatigue properties in ABS/GNPs composites.

Understanding the influence of environmental conditions on the low cycle fatigue behaviour of high strength low alloy (HSLA) steel under air and corrosive (3.5% NaCl) conditions

Offshore structures which are made up of high-strength low alloy (HSLA) steel experience fatigue load due to sea waves and corrosion. In the present work, the influence of environmental conditions (air and 3.5 % NaCl solution) on the strain-controlled fatigue life of High Strength Low Alloy (HSLA) steel has been determined. Low cycle fatigue experiments were conducted on HSLA steel specimens of 12 mm diameter which were prepared parallel to the rolling direction. The strain amplitude was varied in the range of 0.4 to 0.7 % for a constant test frequency of 0.3 Hz. For all the total strain amplitudes (Δεt/2), a significant reduction in fatigue life was observed while testing the specimens under the presence of 3.5 % NaCl solution compared to the air environment. Microscopic investigation indicates that rigorous grain boundary oxidation has happened, and it has created the grain boundary cracking and several sites for fatigue crack initiation and propagation. The presence of corrosive compounds (Fe2O3, FeOOH) was also confirmed by the X-ray diffraction patterns. In addition, mixed modes (transannular and intergranular) of fractures were observed due to the presence of 3.5 % NaCl solution.

Understanding seawater-induced fatigue changes in glass/epoxy laminates: A SEM, EDS, and FTIR study

Composite polymeric materials have exhibited significant advantages when operating in hostile conditions such as the marine environment. However, there is a lack of information concerning three-dimensional variations induced by prolonged exposure to seawater in composite structures and their impact on fatigue performance. Thus, this study aims to investigate the effects of long-term exposure to natural seawater on both the fatigue strength and three-dimensional chemical changes of GFRP laminates. Fatigue tests were conducted under uniaxial cyclic loading at a stress ratio R = 0.1, considering three groups of specimens: a control group not immersed in natural seawater, a group immersed for 230 days in natural seawater, and a group immersed for 910 days in natural seawater. After the tests, fracture surfaces were analysed using scanning electron microscopy (SEM) and energy-dispersive spectrometry (EDS). SEM examination revealed the microstructural occurrence of fibre-matrix debonding, reducing the load transfer between the fibre and matrix, contributing to the fatigue life decrease in immersed specimens. The fatigue results revealed that the reduction in fatigue life of the specimens immersed for 230 days was approximately 66 % of that observed in the control specimens increasing to 95 % when the immersion period extended to 910 days. Moreover, the effect of immersion time on the chemical structure of various regions within the specimens was assessed using Fourier-transform infrared (FTIR) spectroscopy. The main findings suggest the existence of a concentration gradient within the laminate and that regions near permeable surfaces are more vulnerable to chemical changes compared to regions located further away, even after reaching saturation.

A fatigue life model accounting for the combined effect of surface roughness and microstructure: Application to SLM fabricated Hastelloy-X

This study introduces a microstructure-sensitive fatigue life prediction framework based on CP-FFT which includes the effect of surface roughness. The model is applied to flat Hastelloy-X specimens fabricated using Selective Laser Melting. The surface roughness measured is incorporated introducing a free surface with sinusoidal profile. The framework can accurately predict the fatigue life reduction of rough flat specimens using the fatigue parameters of polished bulk specimens and introducing the actual microstructure and roughness. A parametric study shows a monotonic reduction of life with the roughness amplitude but a minor effect of the surface waviness.

Fretting fatigue tests on 6201-T81 aluminum alloy conductor wires at room temperature and 75 °C

The aim of this work was to conduct a test campaign to investigate the effect of temperature on the fretting fatigue life of aluminum alloy 6201-T81 wires taken from All Aluminum Alloy Conductors (AAAC) 900 MCM. To this end, fretting fatigue tests were conducted at room temperature (25 °C) and 75 °C. A three actuators fretting fatigue rig was upgraded with a heating system to allow the tests at elevated temperatures with an accuracy of ±2 °C. A methodology to ease the control of the temperature within the contact region was proposed and the details of the wire-against-wire fretting fatigue test were described. Two S–N curves were then obtained under the same load conditions, but each one at a different temperature. The results showed that at higher temperature the fretted wires could face up to 72 % reduction in fatigue life. Failure analysis of the fracture surfaces proved that the fatigue phenomenon in both conditions, i.e., at 25 °C and 75 °C, were very similar even though fatigue lives are quite different.

РАСЧЕТ НДС РАМНЫХ УЗЛОВ СТРОИТЕЛЬНЫХ МЕТАЛЛОКОНСТРУКЦИИ ПРИ ИХ УСИЛЕНИИ

Experience in the operation of reinforced metal structures of industrial buildings has shown that under increased influence of static loads, units of frame elements rarely fail, which cannot be noted in the case of prolonged application of dynamic loads. As a rule, welded joints of fastenings of reinforcement elements are subject to destruction, which is the reason for conducting this study. During the work, the influence of residual welding stresses on the durability of reinforced frame assemblies under the influence of dynamic loads was revealed. The numerical modeling method was used using the Ansys SpaceClaim software package. The vibration strength of seams is determined by the height of the leg of welded joints associated with the transition of the material to the stage of deformation and displacement of structural units subjected to cyclic loading. It should be noted that fatigue failure is divided into two categories: high-cycle fatigue and low-cycle fatigue. High-cycle fatigue, when the number of cycles of load application is large (around 1e4 - 1e9). With this formulation, the stress level is usually lower in comparison with the ultimate strength of the material. Durability assessment, depending on the stress level, is usually used to calculate high-cycle fatigue. Low-cycle fatigue, when the number of cycles of the applied load is relatively small. Plastic deformation is often associated with low cycle fatigue calculations and results in reduced fatigue life. Assessment of durability depending on the level of deformation is more applicable to the calculation of low-cycle fatigue.

Fatigue of 1.5 Single-Shear Lap Joints with Sealant and Corrosion-Inhibiting Compounds

Corrosion-inhibiting compounds (CICs) are a secondary protection method used with aircraft that can reduce the rate of corrosion development. However, CICs can also affect the fatigue life of fastened lap joints. This study uses a 1.5 single-shear lap joint design to investigate fatigue life changes with CIC application. Hi-Lok and rivet fastener types are compared, along with the inclusion of faying surface sealant. It was found that without sealant, the application of CICs increased the fatigue life due to prolonging the crack initiation process. The presence of faying surface sealant led to a reduction in fatigue life for the rivet samples. The Hi-Lok samples saw no change in life due to the squeeze-out of the sealant around the fastener holes. This study provides a foundational understanding of the mechanisms and significance of the change in fatigue life with the presence of CICs and faying surface sealant in a fastened lap joint.

Reliability Analysis of Compressive Fatigue Life of Cement Concrete under Temperature Differential Cycling

Cement concrete, as an extensively used engineering material, is omnipresent in various infrastructure projects such as bridges and roads. However, these structures often need to operate for extended periods under varying and harsh environmental conditions, facing not only complex vehicular loads but also the effects of temperature differential cycling. Consequently, understanding how temperature differential cycling impacts the compressive fatigue life of cement concrete has become a pivotal research topic. In this study, through a comprehensive experimental design, the fatigue life of cement concrete under typical temperature difference conditions (20–60°C) and different number of temperature differential cycling (60, 120, 180, 240, 300) was tested at three stress levels (0.70, 0.75, 0.85). Statistical analysis was conducted to obtain the Weibull distribution parameters of the compressive fatigue life of cement concrete. The Pf–S–N relationship of concrete considering reliability was analyzed, and a fatigue life prediction model under different reliability probabilities was established. The results show that the fatigue life of concrete subjected to temperature differential cycling follows a two-parameter Weibull distribution well. From the Pf–N curve, it can be seen that, regardless of the stress level, the calculated fatigue life under the same reliability probability decreases with the increase of temperature differential cycling times. At a 95% reliability probability, the decrease can reach 77.5%–87.5%. Based on the exponential function, a concrete fatigue life prediction model based on different reliability levels was established. Using this model, the S–lgN curve was plotted, and it was found that, regardless of the temperature differential cycling, an increase in reliability probability could lead to a 7.3%–14.4% reduction in logarithmic fatigue life (lgN). Additionally, this study also defined a fatigue life safety factor related to the number of temperature differential cycling and reliability probability, aiming to provide a theoretical basis for the design of cement concrete materials under the coupled environment of temperature differential cycling and fatigue loading.

The role of peening processes as a pre‐treatment to anodizing on fatigue behavior of aircraft aluminum alloy

AbstractIn this work, the possibility of employing shot peening and laser peening as pre‐treatments to a tartaric–sulfuric anodizing process on the fatigue behavior of 7050‐T7451 aluminum alloy components was investigated. The surface modifications and stress fields induced by the combination of the peening and anodizing processes were evaluated by scanning electron microscopy and residual stress assessment methodologies based on diffraction techniques, respectively. It was found that the anodizing process alone results in a significant reduction in fatigue life compared to the as‐machined condition especially in the high‐cycle fatigue (HCF) region of the S–N diagrams due to the presence of defects within the anodic layer that act as stress concentrators facilitating the initiation of fatigue cracks. The application of both shot and laser peening treatments is demonstrated to offset the negative effects induced by anodizing, offering greater safety margins useful for the design of critical aeronautical structures.

Influence of build direction on the ratchetting-fatigue interaction of heat-treated additively manufactured 316L stainless steel

This study has investigated the cyclic deformation and ratchetting-fatigue interaction of 316L stainless steel fabricated by laser powder bed fusion (LPBF) and subjected to a 900 °C/2 h post-heat treatment, considering both the vertical and horizontal orientations. Strain- and stress-controlled low cycle fatigue (LCF) tests are conducted to explore the cyclic deformation and the effects of the mean stress and stress amplitude on the fatigue life and ratchetting deformation. A detailed analysis of the cyclic deformation mechanism is conducted through X-ray microtomography and transmission electron microscope (TEM) observations. The results show that post-heat treated LPBF 316L steel exhibits cyclic hardening followed by a non-saturated cyclic softening stage. This behavior is attributed to the evolution of dislocation density and dislocation patterns, and the formation of surface cracks. The ratchetting strain and its rate are sensitive to the mean stress and stress amplitude. The fatigue lives of vertically built specimens are slightly higher under strain-controlled loading conditions, but significantly lower under stress-controlled loading conditions than those of horizontally built ones. Furthermore, ratchetting deformation can promote fatigue damage, resulting in a reduction in fatigue life.

Low-cycle fatigue mechanical behavior of 30CrMo steel under hydrogen environment and numerical verification of chaboche model

In order to investigate the fatigue behavior of the hydrogen storage material, 30CrMo steel, in a hydrogen environment, an electrochemical hydrogen charging method was employed. Low-cycle fatigue experiments were conducted on the material to obtain half-life stress–strain hysteresis curves, cyclic response characteristics, and strain-life relationships under different hydrogen charging durations. The results indicate that the material exhibited an overall cyclic softening behavior, transitioning from ductile fracture to brittle fracture after hydrogen charging, resulting in a significant reduction in fatigue life. The Manson-Coffin formula was fitted based on material cyclic response characteristics and strain-life relationship curves. Additionally, fatigue toughness and Chaboche kinematic hardening models were fitted based on low-cycle fatigue test data. Finite element analysis was used to validate the accuracy and reliability of the Chaboche kinematic hardening model. The Chaboche kinematic hardening model showed minimal error compared to experimental data and accurately described the influence of hydrogen on the low-cycle fatigue mechanical behavior of 30CrMo steel.

Numerical analysis of inflow turbulence intensity impact on the stress and fatigue life of vertical axis hydrokinetic turbine

The present study aims to analyze the effect of upstream turbulence intensity on the hydrodynamic and structural performance of the straight-blade vertical axis turbine. To achieve this, a one-way fluid structure interaction analysis is conducted within the ANSYS workbench environment. Initially, computational fluid dynamics (CFD) simulation is performed at different values of upstream velocity values. Additionally, the impact of upstream turbulence intensity is also analyzed. The CFD simulation results were validated against published experimental work. Once CFD simulation is performed then computed fluid loads are transferred to the ANSYS mechanical structural module. Finite element modeling is performed to compute the stresses and the fatigue life. The study reveals that increasing the upstream turbulence intensity from 5% to 20% leads to 8.6% improvement in the turbine's power performance. However, turbulence intensity also results in 35.6% increase in Von-Mises stresses produced within the designed turbine. However, even with this increase, the Von-Mises stresses remain below a critical threshold, measuring at 173.34 MPa when the upstream water velocity is 1.4 m/s, and the inflow turbulence intensity is at 20%. This stress level is well within the material's yield strength, ensuring the turbine's structural integrity. Moreover, the simulation results emphasize that turbulence intensity has a significant impact on the turbine's fatigue life. Further, it is predicted that an increase in turbulence intensity from 5% to 20% leads to a significant 40% reduction in the turbine's fatigue life. The stress analysis results reveal that struts, strut–blade joints, and strut–shaft joints are the key stress concentration areas. The results suggested that an increase in upstream turbulence intensity has favorable impact on turbine performance, however, for highly turbulent flows turbine should have higher strength and key areas should be focused on designing turbine for such flow conditions.

Effect of chemical milling and anodizing on the high cycle fatigue behaviour of 2024-T3 aluminium alloy

Aluminium 2024-T3 alloy, widely employed in transport aircraft wing and fuselage skin structures, necessitates thickness reduction for weight optimization. Chemical milling is utilized for this purpose; however, it removes Cladding (as a standard corrosion protection layer), prompting subsequent anodizing and sealing to provide corrosion protection. Literature indicates that anodizing or chemical milling can significantly reduce fatigue life, and limited data have been available on the life of chemically milled anodized materials. In this study, constant amplitude stress-life (S-N) testing was performed on two sets of fatigue samples: Cladded Aluminium Alloy (CAA) 2024-T3 sheet specimens (1.6 mm thick) and chemically milled, anodized and sealed (CMAS-AA) Aluminum Alloy sheet specimens (1 mm thick). S-N curves were generated at R=0.1 and room temperature under stress control. SEM micrographs showed micropores in CMAS-AA and a standard plain surface in CAA, consistent with prior findings. Both types exhibited 3-5 times shorter fatigue life than electropolished samples, as reported in MIL Handbook HDBK-5J, highlighting the importance of corrosion protection techniques for structural integrity. Residual stresses were observed, with cladded samples displaying compressive and CMAS-AA exhibiting tensile stresses. Fractography revealed no abnormal fatigue fracture features, and computed plane stress fracture toughness values estimated using measured crack size from the failed specimens matched standard values of aluminium alloys.