BACKGROUND Parkinson’s disease(PD)is a common neurodegenerative disorder in the elderly population.Non-motor symptoms such as anxiety and depression are often subtle,hindering early detection and intervention,yet the...BACKGROUND Parkinson’s disease(PD)is a common neurodegenerative disorder in the elderly population.Non-motor symptoms such as anxiety and depression are often subtle,hindering early detection and intervention,yet they markedly affect quality of life and clinical outcomes.AIM To investigate the prevalence of anxiety and depression in elderly PD patients,identify associated risk factors,and assess their relationship with fatigue severity.METHODS A cross-sectional analysis was conducted in 123 elderly PD patients treated at The Second Rehabilitation Hospital of Shanghai between January 2023 and December 2024.Demographic and clinical data were obtained using standardized questionnaires.Anxiety,depression,and fatigue were assessed using the Beck Anxiety Inventory(BAI),Geriatric Depression Scale(GDS),and Fatigue Scale-14(FS-14),respectively.Binary logistic regression identified risk factors for anxiety and depression,whereas Spearman’s correlation assessed associations with fatigue.RESULTS Anxiety and depression prevalence rates were 64.2%(mean BAI score:19.59±10.92)and 56.1%(mean GDS score:12.82±6.37),respectively.The mean FS-14 total score was 9.46±1.89,comprising physical(5.77±1.51)and mental(3.69±1.20)fatigue components.Significant positive correlations were observed between fatigue scores(total,physical,and mental)and both anxiety and depression(all P<0.05).Univariate analysis revealed statistically significant associations between anxiety/depression and monthly income,disease duration,and disease severity(all P<0.05).Multivariate logistic regression indicated higher anxiety risk in patients with lower monthly income,prolonged disease duration,advanced disease severity,or multimorbidity.Depression risk was elevated in patients with lower monthly income and severe disease,whereas longer disease duration unexpectedly served as a protective factor.CONCLUSION Elderly PD patients show high rates of anxiety and depression,both of which are significantly correlated with fatigue severity.These findings highlight the importance of psychological monitoring and targeted mental health interventions in PD management among the elderly.展开更多
Myalgic encephalomyelitis/chronic fatigue syndrome-an insidious disease:The recent COVID-19 pandemic has brought substantial attention to the overlapping symptoms between long COVID and myalgic encephalomyelitis/chron...Myalgic encephalomyelitis/chronic fatigue syndrome-an insidious disease:The recent COVID-19 pandemic has brought substantial attention to the overlapping symptoms between long COVID and myalgic encephalomyelitis/chronic fatigue syndrome(ME/CFS),a chronic and poorly understood neurological disorder(Shankar et al.,2024).展开更多
Accurately predicting fatigue life under multiaxial fatigue damage conditions is essential for ensuring the safety of critical components in service.However,due to the complexity of fatigue failure mechanisms,achievin...Accurately predicting fatigue life under multiaxial fatigue damage conditions is essential for ensuring the safety of critical components in service.However,due to the complexity of fatigue failure mechanisms,achieving accurate multiaxial fatigue life predictions remains challenging.Traditional multiaxial fatigue prediction models are often limited by specific material properties and loading conditions,making it difficult to maintain reliable life prediction results beyond these constraints.This paper presents a study on the impact of seven key feature quantities on multiaxial fatigue life,using Convolutional Neural Networks(CNN),Long Short-Term Memory Networks(LSTM),and Fully Connected Neural Networks(FCNN)within a deep learning framework.Fatigue test results from eight metal specimens were analyzed to identify these feature quantities,which were then extracted as critical time-series features.Using a CNN-LSTM network,these features were combined to form a feature matrix,which was subsequently input into an FCNN to predict metal fatigue life.A comparison of the fatigue life prediction results from the STFAN model with those from traditional prediction models—namely,the equivalent strain method,the maximum shear strain method,and the critical plane method—shows that the majority of predictions for the five metal materials and various loading conditions based on the STFAN model fall within an error band of 1.5 times.Additionally,all data points are within an error band of 2 times.These findings indicate that the STFAN model provides superior prediction accuracy compared to the traditional models,highlighting its broad applicability and high precision.展开更多
The paper designs a novel material-level specimen and its dedicated fixture suitable for applying Combined high-and low-Cycle Fatigue(CCF)loads.Unlike full-scale or simulation specimens,the CCF specimen eliminates geo...The paper designs a novel material-level specimen and its dedicated fixture suitable for applying Combined high-and low-Cycle Fatigue(CCF)loads.Unlike full-scale or simulation specimens,the CCF specimen eliminates geometrically induced stress gradients in the test region.Experimental data on CCF life and strain responses of ZSGH4169 alloy are acquired under different CCF loads.The Maximum Strain within Each(MSE)CCF cycle is demonstrated to be independent of the Low-Cycle Fatigue(LCF)loads and High-Cycle Fatigue(HCF)stress amplitudes,but exhibits a correlation with the Cycle Ratio of HCF/LCF(Rf).The growth law of MSE changes from linear to logarithmic as Rfdecreases.Strain amplitudes in the dwell stage,observed unaffected by Rf,are quantified as a function of LCF nominal stresses and HCF stress amplitudes.However,under a defined CCF load,strain amplitudes in the dwell stage remain constant.Strain peaks in the dwell stage in a single CCF cycle decrease in a power function with increasing HCF cycles.展开更多
Fatigue failure continues to be a significant challenge in designing structural and mechanical components subjected to repeated and complex loading.While earlier studies mainly examined material properties and how str...Fatigue failure continues to be a significant challenge in designing structural and mechanical components subjected to repeated and complex loading.While earlier studies mainly examined material properties and how stress affects lifespan,this review offers the first comprehensive,multiscale comparison of strategies that optimize geometry to improve fatigue performance.This includes everything from microscopic features like the shape of graphite nodules to large-scale design elements such as fillets,notches,and overall structural layouts.We analyze and combine various methods,including topology and shape optimization,the ability of additive manufacturing to finetune internal geometries,and reliability-based design approaches.A key new contribution is our proposal of a standard way to evaluate geometry-focused fatigue design,allowing for consistent comparison and encouraging validation across different fields.Furthermore,we highlight important areas for future research,such as incorporating manufacturing flaws,using multiscale models,and integrating machine learning techniques.This work is the first to provide a broad geometric viewpoint in fatigue engineering,laying the groundwork for future design methods that are driven by data and centered on reliability.展开更多
The ability to predict multiaxial fatigue life of Al-Alloy 7075-T6 under complex loading conditions is critical to assessing its durability under complex loading conditions,particularly in aerospace,automotive,and str...The ability to predict multiaxial fatigue life of Al-Alloy 7075-T6 under complex loading conditions is critical to assessing its durability under complex loading conditions,particularly in aerospace,automotive,and structural applications.This paper presents a physical-informed neural network(PINN)model to predict the fatigue life of Al-Alloy 7075-T6 over a variety of multiaxial stresses.The model integrates the principles of the Geometric Multiaxial Fatigue Life(GMFL)approach,which is a novel fatigue life prediction approach to estimating fatigue life by combining multiple fatigue criteria.The proposed model aims to estimate fatigue damage accumulation by the GMFL method.The proposed GMFL-PINN combines this physics-based approach with data-driven neural networks.Experimental validation demonstrates that GMFL-PINN outperforms FS,Smith–Watson–Topper(SWT)and Li–Zhang(LZH)fatigue life prediction methods which provides a reliable and scalable solution for structural health assessment and fatigue analysis.展开更多
This paper aims to experimentally and numerically probe fatigue behaviours and lifetimes of 3D4D(three-dimensional four-directional)braided composite I-beam under four-point flexure spectrum loading.New fatigue damage...This paper aims to experimentally and numerically probe fatigue behaviours and lifetimes of 3D4D(three-dimensional four-directional)braided composite I-beam under four-point flexure spectrum loading.New fatigue damage models of fibre yarn,matrix and fibre–matrix interface are proposed,and fatigue failure criteria and PFDA(Progressive Fatigue Damage Algorithm)are thus presented for meso-scale fatigue damage modelling of 3D4D braided composite I-beam.To validate the aforementioned model and algorithm,fatigue tests are conducted on the 3D4D braided composite I-beam under four-point flexure spectrum loading,and fatigue failure mechanisms are analyzed and discussed.Novel global–local FE(Finite Element)model based on the PFDA is generated for modelling progressive fatigue failure process and predicting fatigue life of 3D4D braided composite I-beam under four-point flexure spectrum loading.Good agreement has been achieved between experimental results and predictions,demonstrating the effective usage of new model.It is shown that matrix cracking and interfacial debonding initially initiates on top surface of top flange of I-beam,and then gradually propagates from the side surface of top flange to the intermediate web along the braiding angle,and considerable fiber breakage finally causes final fatigue failure of I-beam.展开更多
Cancer-related fatigue(CRF)presents as a complex interplay between physical and mental fatigue,with mindfulness interventions offering a promising approach to alleviate both.These techniques,including mindfulness-base...Cancer-related fatigue(CRF)presents as a complex interplay between physical and mental fatigue,with mindfulness interventions offering a promising approach to alleviate both.These techniques,including mindfulness-based stress reduction,cognitive therapy,dialectical behavior therapy,and acceptance and commitment therapy,are designed to break the cycle of CRF by addressing its psychological and emotional aspects.This editorial integrates the latest research published by Liu et al,examining the reciprocal and harmful cyclical relationship between physical and mental CRF,and explores the causes and associated mindfulness interventions.We expect that future research will emphasize the identification and management of CRF,particularly focusing on the application of various mindfulness interventions in cancer survivors and patients undergoing cancer treatment,as well as the development of mindfulness in the era of new technologies.展开更多
To accurately predict the fatigue properties of additively manufactured(AM)titanium alloys,it is important to understand the fatigue damage origin behavior.However,this behavior is still ambiguous.Therefore,the effect...To accurately predict the fatigue properties of additively manufactured(AM)titanium alloys,it is important to understand the fatigue damage origin behavior.However,this behavior is still ambiguous.Therefore,the effects of internal defects and microstructures on the fatigue damage origin behavior of laser direct energy deposited TC11(LDED-TC11)alloy were investigated using a fatigue origin criterion.The criterion was proposed to analyze the competing and combining effects by coupling the plasticity-corrected crack driving force,the resistance of short cracks,and the modified Kitagawa-Takahashi diagram.Three scenarios corresponding to the criterion were clarified,representing the damage mechanisms dominated by the microstructure,the combined effect of internal defect and microstructure,and the internal defect.As a result,the fatigue fracture morphology of high-cycle fatigue tests demonstrates two fatigue origin modes,i.e.microstructure and gas pore origin modes.The two fatigue modes belong to Scenario I and Scenario II,respectively,which indicates that the fatigue damage origin process of this alloy is sensitive to microstructure.Besides,it was found that the width of the primary a phase of this alloy is strongly relevant to intrinsic defect size.Finally,the fatigue origin criterion was verified in three aspects.展开更多
Cold regions often feature complex geological environments where various physical phenomena interact,with a particularly notable thermo-hydro-mechanical(THM)coupling.In this study,fully coupled THM cyclic tests were c...Cold regions often feature complex geological environments where various physical phenomena interact,with a particularly notable thermo-hydro-mechanical(THM)coupling.In this study,fully coupled THM cyclic tests were conducted,followed by fatigue tests,to explore how THM treatment influences the fatigue properties of damaged sandstone.Experimental results indicate that rock fatigue deformation,damage evolution,and failure characteristics are highly sensitive to initial damage caused by coupled THM treatment.Rocks subjected to multiple THM cycles exhibit lower initial irreversible strain,shorter fatigue life,lower critical total dissipated energy,and higher irreversible strain increments,indicating accelerated deterioration.After THM coupling,rock fatigue failure shows complex crack networks,with macroscopic failure modes shifting from shear to tensile failure.Polarized microscopy and acoustic emission analyses reveal that this transition stems from micro-scale transgranular to intergranular fractures.We introduced a fractional order-based damage fatigue model to quantitatively describe the rock viscoelastic parameters after different initial damage treatments.Rock viscoelastic-plastic parameters decrease with increasing coupled THM cycles.Finally,we discussed the feasibility of applying these results to the long-term stability analysis of rock slopes.This study provides unique insights and modeling tools from fully coupled THM experiments to understand the rock fatigue characteristics,offering potential applications for slope stability assessment.展开更多
Fatigue analysis of engine turbine blade is an essential issue.Due to various uncertainties during the manufacture and operation,the fatigue damage and life of turbine blade present randomness.In this study,the random...Fatigue analysis of engine turbine blade is an essential issue.Due to various uncertainties during the manufacture and operation,the fatigue damage and life of turbine blade present randomness.In this study,the randomness of structural parameters,working condition and vibration environment are considered for fatigue life predication and reliability assessment.First,the lowcycle fatigue problem is modelled as stochastic static system with random parameters,while the high-cycle fatigue problem is considered as stochastic dynamic system under random excitations.Then,to deal with the two failure modes,the novel Direct Probability Integral Method(DPIM)is proposed,which is efficient and accurate for solving stochastic static and dynamic systems.The probability density functions of accumulated damage and fatigue life of turbine blade for low-cycle and high-cycle fatigue problems are achieved,respectively.Furthermore,the time–frequency hybrid method is advanced to enhance the computational efficiency for governing equation of system.Finally,the results of typical examples demonstrate high accuracy and efficiency of the proposed method by comparison with Monte Carlo simulation and other methods.It is indicated that the DPIM is a unified method for predication of random fatigue life for low-cycle and highcycle fatigue problems.The rotational speed,density,fatigue strength coefficient,and fatigue plasticity index have a high sensitivity to fatigue reliability of engine turbine blade.展开更多
Additive manufactured titanium alloys exhibit distinct microstructures and internal defects compared to forged alloys.This has a significant impact on its fatigue failure behavior and fatigue life distribution.Fatigue...Additive manufactured titanium alloys exhibit distinct microstructures and internal defects compared to forged alloys.This has a significant impact on its fatigue failure behavior and fatigue life distribution.Fatigue life dispersity and distribution characteristics of laser direct energy deposited Ti-6.5Al-3.5Mo-1.5Zr-0.3Si alloy were investigated by a relatively large sample fatigue test,fracture morphology characterization,and statistical analytic method.Then,the intrinsic causes of fatigue life dispersity and distribution characteristics were clarified by correlating with fatigue failure origin modes(FFOMs).The test and analysis results indicate that the existence of internal pores significantly influences FFOMs,fatigue life dispersity,and distribution pattern.The FFOMs of microstructure and interior pores have little effect on fatigue life dispersion,In contrast,FFOMs of surface and subsurface pores present a relatively lower fatigue life and are responsible for fatigue life dispersion.Besides,two competitive effects of FFOMs with different applied stress highly affect fatigue life distribution.A bimodal Weibull model is more suitable for describing fatigue life distribution with multiple FFOMs.However,if there is no fast-computing procedure for the parameter estimation of the Bimodal Weibull model,relatively conservative and simple P-S-N curves based on the Weibull distribution model are recommended in engineering applications.展开更多
Permeable roads generally exhibit inferior mechanical properties and shorter service life than traditional dense-graded/impermeable roads.Furthermore,the incorporation of recycled aggregates in their construction may ...Permeable roads generally exhibit inferior mechanical properties and shorter service life than traditional dense-graded/impermeable roads.Furthermore,the incorporation of recycled aggregates in their construction may exacerbate these limitations.To address these issues,this study introduced a novel cement-stabilized permeable recycled aggregate material.A total of 162 beam specimens prepared with nine different levels of cement-aggregate ratio were tested to evaluate their permeability,bending load,and bending fatigue life.The experimental results indicate that increasing the content of recycled aggregates led to a reduction in both permeability and bending load.Additionally,the inclusion of recycled aggregates diminished the energy dissipation capacity of the specimens.These findings were used to establish a robust relationship between the initial damage in cement-stabilized permeable recycled aggregate material specimens and their fatigue life,and to propose a predictive model for their fatigue performance.Further,a method for assessing fatigue damage based on the evolution of fatigue-induced strain and energy dissipation was developed.The findings of this study provide valuable insights into the mechanical behavior and fatigue performance of cement-stabilized permeable recycled aggregate materials,offering guidance for the design of low-carbon-emission,permeable,and durable roadways incorporating recycled aggregates.展开更多
In order to obtain the change law of the fatigue reliability of cement concrete for highway pavement under high stress ratios, first, the probability densities of monotonic random variables including concrete fatigue ...In order to obtain the change law of the fatigue reliability of cement concrete for highway pavement under high stress ratios, first, the probability densities of monotonic random variables including concrete fatigue life are deduced. And then, the fatigue damage probability densities of the Miner and Chaboche-Zhao models are deduced. By virtue of laboratory fatigue test results, the fatigue damage probability density functions of the two models can be obtained, considering different stress ratios. Finally, substituting load cycles into them, the change law of cement concrete fatigue reliability about load cycles can be acquired. The results show that under the same stress ratio, with the increase in the load cycle, the fatigue reliability declines from almost 100% to 0% gradually. No matter under what stress ratio, during the initial stage of the load action, there is always a relatively stable phase for fatigue reliability. With the increase in the stress ratio, the stable phase gradually shortens and the load cycle corresponding to the reliability of 0% also decreases. In the descent phase of reliability, the higher the stress ratio is, the lower the concrete reliability is for the same load cycle. Besides, compared with the Chaboche-Zhao fatigue damage model, the Miner fatigue damage model is safer.展开更多
Purpose–This study aims to investigate the fatigue behavior and failure modes of bolted lap joints using Modified Tensile Specimens(MTS)under various cyclic load conditions.Emphasis is placed on identifying the relat...Purpose–This study aims to investigate the fatigue behavior and failure modes of bolted lap joints using Modified Tensile Specimens(MTS)under various cyclic load conditions.Emphasis is placed on identifying the relationship between load amplitude,fatigue life,and damage progression in low-carbon steel assemblies.Design/methodology/approach–An experimental approach was adopted using MTS specimens fabricated from St 1203 cold-rolled steel,joined with Grade 8.8 M4 bolts.Cyclic fatigue tests were conducted under zerobased loading at seven distinct force levels.Fracture surfaces were visually analyzed to identify dominant failure mechanisms.Findings–The results revealed a strong inverse correlation between applied cyclic load and fatigue life.Three distinct failure modes were identified:bolt shear at high loads(5.4 kN),interface cracking and slippage at moderate loads(4.9–5.1 kN),and plate tearing or stable fatigue behavior at lower loads(54.1 kN).The results highlight a progressive transition in failure mechanisms,from bolt shear at high loads to plate tearing and interface cracking at lower loads,providing essential insights for fatigue-resistant bolted joint design.Originality/value–This study offers original insights into the fatigue behavior of bolted lap joints using MTS,a relatively underexplored configuration in fatigue assessment.By experimentally evaluating failure modes under varied cyclic load levels,the authors uncover critical transitions in damage mechanisms—from bolt shear to interface cracking and plate tearing—depending on the applied load.Unlike many existing studies focused on numerical modeling or bonded joints alone,this work provides empirical data rooted in real-world fastening conditions using cold-rolled low-carbon steel.展开更多
Crack initiation mechanism of dwell fatigue has always been a key problem in rationalizing the dwell effect,and it is not completely understood yet.This study conducted stress-controlled low-cycle fatigue and dwell fa...Crack initiation mechanism of dwell fatigue has always been a key problem in rationalizing the dwell effect,and it is not completely understood yet.This study conducted stress-controlled low-cycle fatigue and dwell fatigue tests on Ti-6Al-3Nb-2Zr-1Mo alloy with bimodal microstructure to reveal its microstructural characteristics and crack initiation mechanisms.The study demonstrated that the faceted primaryα nodules located near the specimen surface acted as crack initiation sites during both fatigue and dwell fatigue tests.Slip trace analysis revealed that faceted cracking occurred at(0001)basal plane with the maximum Schmid factor value through a special cracking mode referred to as(0001)twist boundary cracking.Innovative criteria of parameters C1 and C2 were proposed based on experimental observation and molecular dynamics simulations,which well identify candidates for(0001)twist boundary crack nucleation.It demonstrated that grain pairs combining a moderately high Schmid factor for basal slip and a well-orientated Burgers vector in the out-of-surface plane was the preferable location for surface(0001)twist-boundary crack initiation,and grain pairs combining a high Schmid factor for basal slip and a high normal stress on basal plane are perfect candidates for subsurface cracking.Based on this,phenomeno-logical models are proposed to explain the surface(0001)twist-boundary cracking mechanism from the perspective of surface extrusion-intrusion-induced micro-notches.展开更多
The low cycle fatigue(LCF)behaviors and cyclic deformation mechanisms of 2195 Al-Li alloy were inves-tigated under low temperatures(-20℃and-80℃)and different strain amplitudes(0.6%,0.7%,0.8%,and 1.0%).The LCF stress...The low cycle fatigue(LCF)behaviors and cyclic deformation mechanisms of 2195 Al-Li alloy were inves-tigated under low temperatures(-20℃and-80℃)and different strain amplitudes(0.6%,0.7%,0.8%,and 1.0%).The LCF stress responses under conditions of-20℃&0.6%and-80℃&0.6%exhibited initial cyclic hardening followed by cyclic softening.In contrast,the alloy under other LCF conditions displayed continuous cyclic softening.Notably,the alloy demonstrated reduced LCF life under conditions of-80℃and various strain amplitudes.The fatigue life model based on the total strain energy was developed and proven to be more accurate in predicting fatigue life under diverse LCF conditions.Furthermore,the combined kinematic/isotropic hardening constitutive model exhibited excellent performance in simulat-ing hysteresis loops of the alloy,with corresponding calibration errors all below 14%.Additionally,fatigue fracture surfaces under various LCF conditions consistently exhibited prominent cleavage fracture char-acteristics,and the final fracture zone at-80℃showed increased surface roughness.Finally,the cyclic softening mechanisms were found to be dependent on LCF conditions.The debonding of the interface be-tween the T1 phases and the Al matrix was identified as the primary cyclic softening mechanism under conditions of-20℃&0.6%and-80℃&0.6%.Moreover,the cyclic softening effect under-80℃&1.0%was closely associated with localized shearing of T1 phases.Under-20℃&1.0%,a more pronounced cyclic softening behavior was observed,which was primarily attributed to the continuous shearing of T1 phases.展开更多
This study investigates the fatigue crack propagation mechanism of a new high-strength and high-tough Ti-Mo-Cr-V-Nb-Al titanium alloy with three types of microstructures(basketweave structure,lamellar structure,and bi...This study investigates the fatigue crack propagation mechanism of a new high-strength and high-tough Ti-Mo-Cr-V-Nb-Al titanium alloy with three types of microstructures(basketweave structure,lamellar structure,and bimodal structure)through fatigue crack propagation rate tests and fatigue threshold value tests.The resistance of the alloy to fatigue crack propagation was found to be closely correlated with the morphology and distribution ofαparticles,as evidenced by microscopic examination of fracture surfaces and analysis of crack propagation paths.The primaryαparticles demonstrated superior resistance to crack propagation compared to the secondaryαparticles.The basketweave structure showed exceptional resistance to fatigue crack propagation at all stages.The lamellar structure mainly resists long crack propagation during rapid propagation,and its threshold value is the lowest,which makes it easy to produce microcrack propagation.On the contrary,the bimodal structure has the highest threshold value among the three,so its resistance to short crack growth is more excellent,but it has the highest crack growth rate in the higher stress intensity factor range.Theαparticles in the three microstructures also undergo rotational motion relative to the force axis during fatigue crack propagation,thereby adjusting the uneven stress distribution betweenα/βphases through slip behavior and further coordinating deformation.展开更多
To overcome the challenges of limited experimental data and improve the accuracy of empirical formulas,we propose a low-cycle fatigue(LCF)life prediction model for nickel-based superalloys using a data augmentation me...To overcome the challenges of limited experimental data and improve the accuracy of empirical formulas,we propose a low-cycle fatigue(LCF)life prediction model for nickel-based superalloys using a data augmentation method.This method utilizes a variational autoencoder(VAE)to generate low-cycle fatigue data and form an augmented dataset.The Pearson correlation coefficient(PCC)is employed to verify the similarity of feature distributions between the original and augmented datasets.Six machine learning models,namely random forest(RF),artificial neural network(ANN),support vector machine(SVM),gradient-boosted decision tree(GBDT),eXtreme Gradient Boosting(XGBoost),and Categorical Boosting(CatBoost),are utilized to predict the LCF life of nickel-based superalloys.Results indicate that the proposed data augmentation method based on VAE can effectively expand the dataset,and the mean absolute error(MAE),root mean square error(RMSE),and R-squared(R^(2))values achieved using the CatBoost model,with respective values of 0.0242,0.0391,and 0.9538,are superior to those of the other models.The proposed method reduces the cost and time associated with LCF experiments and accurately establishes the relationship between fatigue characteristics and LCF life of nickel-based superalloys.展开更多
Polymethyl methacrylate(PMMA)has the advantages of good transparency,corrosion resistance and light weight and can be used as the preferred material for pressure-resistant cabins of fully transparent submersibles.In t...Polymethyl methacrylate(PMMA)has the advantages of good transparency,corrosion resistance and light weight and can be used as the preferred material for pressure-resistant cabins of fully transparent submersibles.In this study,based on the fracture mechanics method,a calculation method for estimating the residual fatigue life of a PMMA manned cabin is proposed by improving the small-time scale fatigue crack growth rate model.This improved model is verified by the experimental data of the PMMA material.Then,through the Weibull and Gumbel combined distribution functions,the fatigue load spectrum suitable for the fully transparent manned cabin is fitted according to the dive data.A parametric analysis of the residual fatigue life of the fully transparent manned cabin under various initial crack sizes and dwell time is conducted,yielding valuable results.This study aims to increase the safety of fully transparent pressure-resistant cabins and offer insights for fatigue analysis of underwater structures utilizing PMMA materials.展开更多
基金Supported by Foundation of Shanghai Baoshan Science and Technology Commission,No.2024-E-66Shanghai Nursing Association Scientific Research Project,No.2024MS-B02.
文摘BACKGROUND Parkinson’s disease(PD)is a common neurodegenerative disorder in the elderly population.Non-motor symptoms such as anxiety and depression are often subtle,hindering early detection and intervention,yet they markedly affect quality of life and clinical outcomes.AIM To investigate the prevalence of anxiety and depression in elderly PD patients,identify associated risk factors,and assess their relationship with fatigue severity.METHODS A cross-sectional analysis was conducted in 123 elderly PD patients treated at The Second Rehabilitation Hospital of Shanghai between January 2023 and December 2024.Demographic and clinical data were obtained using standardized questionnaires.Anxiety,depression,and fatigue were assessed using the Beck Anxiety Inventory(BAI),Geriatric Depression Scale(GDS),and Fatigue Scale-14(FS-14),respectively.Binary logistic regression identified risk factors for anxiety and depression,whereas Spearman’s correlation assessed associations with fatigue.RESULTS Anxiety and depression prevalence rates were 64.2%(mean BAI score:19.59±10.92)and 56.1%(mean GDS score:12.82±6.37),respectively.The mean FS-14 total score was 9.46±1.89,comprising physical(5.77±1.51)and mental(3.69±1.20)fatigue components.Significant positive correlations were observed between fatigue scores(total,physical,and mental)and both anxiety and depression(all P<0.05).Univariate analysis revealed statistically significant associations between anxiety/depression and monthly income,disease duration,and disease severity(all P<0.05).Multivariate logistic regression indicated higher anxiety risk in patients with lower monthly income,prolonged disease duration,advanced disease severity,or multimorbidity.Depression risk was elevated in patients with lower monthly income and severe disease,whereas longer disease duration unexpectedly served as a protective factor.CONCLUSION Elderly PD patients show high rates of anxiety and depression,both of which are significantly correlated with fatigue severity.These findings highlight the importance of psychological monitoring and targeted mental health interventions in PD management among the elderly.
基金supported by the Judith Jane Mason and Harold Stannett Williams Memorial Foundation National Medical Program(#Mason2210)to JX。
文摘Myalgic encephalomyelitis/chronic fatigue syndrome-an insidious disease:The recent COVID-19 pandemic has brought substantial attention to the overlapping symptoms between long COVID and myalgic encephalomyelitis/chronic fatigue syndrome(ME/CFS),a chronic and poorly understood neurological disorder(Shankar et al.,2024).
基金supported by Key Program of National Natural Science Foundation of China(U2368215)the Science and Technology Research and Development Program Project of China Railway Group Co.,Ltd.(N2023J056).
文摘Accurately predicting fatigue life under multiaxial fatigue damage conditions is essential for ensuring the safety of critical components in service.However,due to the complexity of fatigue failure mechanisms,achieving accurate multiaxial fatigue life predictions remains challenging.Traditional multiaxial fatigue prediction models are often limited by specific material properties and loading conditions,making it difficult to maintain reliable life prediction results beyond these constraints.This paper presents a study on the impact of seven key feature quantities on multiaxial fatigue life,using Convolutional Neural Networks(CNN),Long Short-Term Memory Networks(LSTM),and Fully Connected Neural Networks(FCNN)within a deep learning framework.Fatigue test results from eight metal specimens were analyzed to identify these feature quantities,which were then extracted as critical time-series features.Using a CNN-LSTM network,these features were combined to form a feature matrix,which was subsequently input into an FCNN to predict metal fatigue life.A comparison of the fatigue life prediction results from the STFAN model with those from traditional prediction models—namely,the equivalent strain method,the maximum shear strain method,and the critical plane method—shows that the majority of predictions for the five metal materials and various loading conditions based on the STFAN model fall within an error band of 1.5 times.Additionally,all data points are within an error band of 2 times.These findings indicate that the STFAN model provides superior prediction accuracy compared to the traditional models,highlighting its broad applicability and high precision.
基金co-supported by the National Natural Science Foundation of China(51805017)National Science and Technology Project(J2017-IV-0012-0049)+1 种基金National Science and Technology Project,China(J2019-IV-0007-0075)the Fundamental Research Funds for the Central Universities,China(JKF-20240036).
文摘The paper designs a novel material-level specimen and its dedicated fixture suitable for applying Combined high-and low-Cycle Fatigue(CCF)loads.Unlike full-scale or simulation specimens,the CCF specimen eliminates geometrically induced stress gradients in the test region.Experimental data on CCF life and strain responses of ZSGH4169 alloy are acquired under different CCF loads.The Maximum Strain within Each(MSE)CCF cycle is demonstrated to be independent of the Low-Cycle Fatigue(LCF)loads and High-Cycle Fatigue(HCF)stress amplitudes,but exhibits a correlation with the Cycle Ratio of HCF/LCF(Rf).The growth law of MSE changes from linear to logarithmic as Rfdecreases.Strain amplitudes in the dwell stage,observed unaffected by Rf,are quantified as a function of LCF nominal stresses and HCF stress amplitudes.However,under a defined CCF load,strain amplitudes in the dwell stage remain constant.Strain peaks in the dwell stage in a single CCF cycle decrease in a power function with increasing HCF cycles.
文摘Fatigue failure continues to be a significant challenge in designing structural and mechanical components subjected to repeated and complex loading.While earlier studies mainly examined material properties and how stress affects lifespan,this review offers the first comprehensive,multiscale comparison of strategies that optimize geometry to improve fatigue performance.This includes everything from microscopic features like the shape of graphite nodules to large-scale design elements such as fillets,notches,and overall structural layouts.We analyze and combine various methods,including topology and shape optimization,the ability of additive manufacturing to finetune internal geometries,and reliability-based design approaches.A key new contribution is our proposal of a standard way to evaluate geometry-focused fatigue design,allowing for consistent comparison and encouraging validation across different fields.Furthermore,we highlight important areas for future research,such as incorporating manufacturing flaws,using multiscale models,and integrating machine learning techniques.This work is the first to provide a broad geometric viewpoint in fatigue engineering,laying the groundwork for future design methods that are driven by data and centered on reliability.
文摘The ability to predict multiaxial fatigue life of Al-Alloy 7075-T6 under complex loading conditions is critical to assessing its durability under complex loading conditions,particularly in aerospace,automotive,and structural applications.This paper presents a physical-informed neural network(PINN)model to predict the fatigue life of Al-Alloy 7075-T6 over a variety of multiaxial stresses.The model integrates the principles of the Geometric Multiaxial Fatigue Life(GMFL)approach,which is a novel fatigue life prediction approach to estimating fatigue life by combining multiple fatigue criteria.The proposed model aims to estimate fatigue damage accumulation by the GMFL method.The proposed GMFL-PINN combines this physics-based approach with data-driven neural networks.Experimental validation demonstrates that GMFL-PINN outperforms FS,Smith–Watson–Topper(SWT)and Li–Zhang(LZH)fatigue life prediction methods which provides a reliable and scalable solution for structural health assessment and fatigue analysis.
基金supported by the National Natural Science Foundation of China(No.12472340).
文摘This paper aims to experimentally and numerically probe fatigue behaviours and lifetimes of 3D4D(three-dimensional four-directional)braided composite I-beam under four-point flexure spectrum loading.New fatigue damage models of fibre yarn,matrix and fibre–matrix interface are proposed,and fatigue failure criteria and PFDA(Progressive Fatigue Damage Algorithm)are thus presented for meso-scale fatigue damage modelling of 3D4D braided composite I-beam.To validate the aforementioned model and algorithm,fatigue tests are conducted on the 3D4D braided composite I-beam under four-point flexure spectrum loading,and fatigue failure mechanisms are analyzed and discussed.Novel global–local FE(Finite Element)model based on the PFDA is generated for modelling progressive fatigue failure process and predicting fatigue life of 3D4D braided composite I-beam under four-point flexure spectrum loading.Good agreement has been achieved between experimental results and predictions,demonstrating the effective usage of new model.It is shown that matrix cracking and interfacial debonding initially initiates on top surface of top flange of I-beam,and then gradually propagates from the side surface of top flange to the intermediate web along the braiding angle,and considerable fiber breakage finally causes final fatigue failure of I-beam.
基金Supported by Education and Teaching Reform Project of the First Clinical College of Chongqing Medical University,No.CMER202305Natural Science Foundation of Tibet Autonomous Region,No.XZ2024ZR-ZY100(Z)the Program for Youth Innovation in Future Medicine,Chongqing Medical University,China,No.W0138.
文摘Cancer-related fatigue(CRF)presents as a complex interplay between physical and mental fatigue,with mindfulness interventions offering a promising approach to alleviate both.These techniques,including mindfulness-based stress reduction,cognitive therapy,dialectical behavior therapy,and acceptance and commitment therapy,are designed to break the cycle of CRF by addressing its psychological and emotional aspects.This editorial integrates the latest research published by Liu et al,examining the reciprocal and harmful cyclical relationship between physical and mental CRF,and explores the causes and associated mindfulness interventions.We expect that future research will emphasize the identification and management of CRF,particularly focusing on the application of various mindfulness interventions in cancer survivors and patients undergoing cancer treatment,as well as the development of mindfulness in the era of new technologies.
基金supported by the National Natural Science Foundation of China(Nos.5175018,52090044)the 2025 Science and Technology Innovation Program of Ningbo,China(No.2022Z014)。
文摘To accurately predict the fatigue properties of additively manufactured(AM)titanium alloys,it is important to understand the fatigue damage origin behavior.However,this behavior is still ambiguous.Therefore,the effects of internal defects and microstructures on the fatigue damage origin behavior of laser direct energy deposited TC11(LDED-TC11)alloy were investigated using a fatigue origin criterion.The criterion was proposed to analyze the competing and combining effects by coupling the plasticity-corrected crack driving force,the resistance of short cracks,and the modified Kitagawa-Takahashi diagram.Three scenarios corresponding to the criterion were clarified,representing the damage mechanisms dominated by the microstructure,the combined effect of internal defect and microstructure,and the internal defect.As a result,the fatigue fracture morphology of high-cycle fatigue tests demonstrates two fatigue origin modes,i.e.microstructure and gas pore origin modes.The two fatigue modes belong to Scenario I and Scenario II,respectively,which indicates that the fatigue damage origin process of this alloy is sensitive to microstructure.Besides,it was found that the width of the primary a phase of this alloy is strongly relevant to intrinsic defect size.Finally,the fatigue origin criterion was verified in three aspects.
基金supported by the National Natural Science Foundation of China(Grant No.42372326)supported by the State Key Laboratory of Geohazard Prevention and Geoenvironment Protection Independent Research Project(Grant No.SKLGP2023Z015)supported by the Sichuan Science and Technology Program(Grant No.2024YFFK0416).
文摘Cold regions often feature complex geological environments where various physical phenomena interact,with a particularly notable thermo-hydro-mechanical(THM)coupling.In this study,fully coupled THM cyclic tests were conducted,followed by fatigue tests,to explore how THM treatment influences the fatigue properties of damaged sandstone.Experimental results indicate that rock fatigue deformation,damage evolution,and failure characteristics are highly sensitive to initial damage caused by coupled THM treatment.Rocks subjected to multiple THM cycles exhibit lower initial irreversible strain,shorter fatigue life,lower critical total dissipated energy,and higher irreversible strain increments,indicating accelerated deterioration.After THM coupling,rock fatigue failure shows complex crack networks,with macroscopic failure modes shifting from shear to tensile failure.Polarized microscopy and acoustic emission analyses reveal that this transition stems from micro-scale transgranular to intergranular fractures.We introduced a fractional order-based damage fatigue model to quantitatively describe the rock viscoelastic parameters after different initial damage treatments.Rock viscoelastic-plastic parameters decrease with increasing coupled THM cycles.Finally,we discussed the feasibility of applying these results to the long-term stability analysis of rock slopes.This study provides unique insights and modeling tools from fully coupled THM experiments to understand the rock fatigue characteristics,offering potential applications for slope stability assessment.
基金supports of the National Natural Science Foundation of China(Nos.12032008,12102080)the Fundamental Research Funds for the Central Universities,China(No.DUT23RC(3)038)are much appreciated。
文摘Fatigue analysis of engine turbine blade is an essential issue.Due to various uncertainties during the manufacture and operation,the fatigue damage and life of turbine blade present randomness.In this study,the randomness of structural parameters,working condition and vibration environment are considered for fatigue life predication and reliability assessment.First,the lowcycle fatigue problem is modelled as stochastic static system with random parameters,while the high-cycle fatigue problem is considered as stochastic dynamic system under random excitations.Then,to deal with the two failure modes,the novel Direct Probability Integral Method(DPIM)is proposed,which is efficient and accurate for solving stochastic static and dynamic systems.The probability density functions of accumulated damage and fatigue life of turbine blade for low-cycle and high-cycle fatigue problems are achieved,respectively.Furthermore,the time–frequency hybrid method is advanced to enhance the computational efficiency for governing equation of system.Finally,the results of typical examples demonstrate high accuracy and efficiency of the proposed method by comparison with Monte Carlo simulation and other methods.It is indicated that the DPIM is a unified method for predication of random fatigue life for low-cycle and highcycle fatigue problems.The rotational speed,density,fatigue strength coefficient,and fatigue plasticity index have a high sensitivity to fatigue reliability of engine turbine blade.
基金supported by the National Natural Science Foundation of China(Nos.51775018&52090044)。
文摘Additive manufactured titanium alloys exhibit distinct microstructures and internal defects compared to forged alloys.This has a significant impact on its fatigue failure behavior and fatigue life distribution.Fatigue life dispersity and distribution characteristics of laser direct energy deposited Ti-6.5Al-3.5Mo-1.5Zr-0.3Si alloy were investigated by a relatively large sample fatigue test,fracture morphology characterization,and statistical analytic method.Then,the intrinsic causes of fatigue life dispersity and distribution characteristics were clarified by correlating with fatigue failure origin modes(FFOMs).The test and analysis results indicate that the existence of internal pores significantly influences FFOMs,fatigue life dispersity,and distribution pattern.The FFOMs of microstructure and interior pores have little effect on fatigue life dispersion,In contrast,FFOMs of surface and subsurface pores present a relatively lower fatigue life and are responsible for fatigue life dispersion.Besides,two competitive effects of FFOMs with different applied stress highly affect fatigue life distribution.A bimodal Weibull model is more suitable for describing fatigue life distribution with multiple FFOMs.However,if there is no fast-computing procedure for the parameter estimation of the Bimodal Weibull model,relatively conservative and simple P-S-N curves based on the Weibull distribution model are recommended in engineering applications.
基金Project(2024JJ2073)supported by the Science Fund for Distinguished Young Scholars of Hunan Province,ChinaProjects(2023YFC3807205,2019YFC1904704)+4 种基金supported by the National Key R&D Program of ChinaProject(52178443)supported by the National Natural Science Foundation of ChinaProject(2024ZZTS0109)supported by Fundamental Research Funds for the Central Universities of Central South University,China。
文摘Permeable roads generally exhibit inferior mechanical properties and shorter service life than traditional dense-graded/impermeable roads.Furthermore,the incorporation of recycled aggregates in their construction may exacerbate these limitations.To address these issues,this study introduced a novel cement-stabilized permeable recycled aggregate material.A total of 162 beam specimens prepared with nine different levels of cement-aggregate ratio were tested to evaluate their permeability,bending load,and bending fatigue life.The experimental results indicate that increasing the content of recycled aggregates led to a reduction in both permeability and bending load.Additionally,the inclusion of recycled aggregates diminished the energy dissipation capacity of the specimens.These findings were used to establish a robust relationship between the initial damage in cement-stabilized permeable recycled aggregate material specimens and their fatigue life,and to propose a predictive model for their fatigue performance.Further,a method for assessing fatigue damage based on the evolution of fatigue-induced strain and energy dissipation was developed.The findings of this study provide valuable insights into the mechanical behavior and fatigue performance of cement-stabilized permeable recycled aggregate materials,offering guidance for the design of low-carbon-emission,permeable,and durable roadways incorporating recycled aggregates.
基金The National Natural Science Foundation of China(No. 51008071 )the Natural Science Foundation of Jiangsu Province(No. BK2010413)
文摘In order to obtain the change law of the fatigue reliability of cement concrete for highway pavement under high stress ratios, first, the probability densities of monotonic random variables including concrete fatigue life are deduced. And then, the fatigue damage probability densities of the Miner and Chaboche-Zhao models are deduced. By virtue of laboratory fatigue test results, the fatigue damage probability density functions of the two models can be obtained, considering different stress ratios. Finally, substituting load cycles into them, the change law of cement concrete fatigue reliability about load cycles can be acquired. The results show that under the same stress ratio, with the increase in the load cycle, the fatigue reliability declines from almost 100% to 0% gradually. No matter under what stress ratio, during the initial stage of the load action, there is always a relatively stable phase for fatigue reliability. With the increase in the stress ratio, the stable phase gradually shortens and the load cycle corresponding to the reliability of 0% also decreases. In the descent phase of reliability, the higher the stress ratio is, the lower the concrete reliability is for the same load cycle. Besides, compared with the Chaboche-Zhao fatigue damage model, the Miner fatigue damage model is safer.
文摘Purpose–This study aims to investigate the fatigue behavior and failure modes of bolted lap joints using Modified Tensile Specimens(MTS)under various cyclic load conditions.Emphasis is placed on identifying the relationship between load amplitude,fatigue life,and damage progression in low-carbon steel assemblies.Design/methodology/approach–An experimental approach was adopted using MTS specimens fabricated from St 1203 cold-rolled steel,joined with Grade 8.8 M4 bolts.Cyclic fatigue tests were conducted under zerobased loading at seven distinct force levels.Fracture surfaces were visually analyzed to identify dominant failure mechanisms.Findings–The results revealed a strong inverse correlation between applied cyclic load and fatigue life.Three distinct failure modes were identified:bolt shear at high loads(5.4 kN),interface cracking and slippage at moderate loads(4.9–5.1 kN),and plate tearing or stable fatigue behavior at lower loads(54.1 kN).The results highlight a progressive transition in failure mechanisms,from bolt shear at high loads to plate tearing and interface cracking at lower loads,providing essential insights for fatigue-resistant bolted joint design.Originality/value–This study offers original insights into the fatigue behavior of bolted lap joints using MTS,a relatively underexplored configuration in fatigue assessment.By experimentally evaluating failure modes under varied cyclic load levels,the authors uncover critical transitions in damage mechanisms—from bolt shear to interface cracking and plate tearing—depending on the applied load.Unlike many existing studies focused on numerical modeling or bonded joints alone,this work provides empirical data rooted in real-world fastening conditions using cold-rolled low-carbon steel.
基金supported by the National Natural Science Foundation of China(Nos.52074231,52274396 and 52001258)the Chongqing Natural Science Foundation(No.cstc2020jcyj-msxmX1056).
文摘Crack initiation mechanism of dwell fatigue has always been a key problem in rationalizing the dwell effect,and it is not completely understood yet.This study conducted stress-controlled low-cycle fatigue and dwell fatigue tests on Ti-6Al-3Nb-2Zr-1Mo alloy with bimodal microstructure to reveal its microstructural characteristics and crack initiation mechanisms.The study demonstrated that the faceted primaryα nodules located near the specimen surface acted as crack initiation sites during both fatigue and dwell fatigue tests.Slip trace analysis revealed that faceted cracking occurred at(0001)basal plane with the maximum Schmid factor value through a special cracking mode referred to as(0001)twist boundary cracking.Innovative criteria of parameters C1 and C2 were proposed based on experimental observation and molecular dynamics simulations,which well identify candidates for(0001)twist boundary crack nucleation.It demonstrated that grain pairs combining a moderately high Schmid factor for basal slip and a well-orientated Burgers vector in the out-of-surface plane was the preferable location for surface(0001)twist-boundary crack initiation,and grain pairs combining a high Schmid factor for basal slip and a high normal stress on basal plane are perfect candidates for subsurface cracking.Based on this,phenomeno-logical models are proposed to explain the surface(0001)twist-boundary cracking mechanism from the perspective of surface extrusion-intrusion-induced micro-notches.
基金supported by the National Natural Science Foundation of China(U23A20626)the Key Research and Devel-opment Program of Shandong Province(2021ZLGX01)the Project of Colleges and Universities Innovation Team of Jinan City(2021GXRC030).
文摘The low cycle fatigue(LCF)behaviors and cyclic deformation mechanisms of 2195 Al-Li alloy were inves-tigated under low temperatures(-20℃and-80℃)and different strain amplitudes(0.6%,0.7%,0.8%,and 1.0%).The LCF stress responses under conditions of-20℃&0.6%and-80℃&0.6%exhibited initial cyclic hardening followed by cyclic softening.In contrast,the alloy under other LCF conditions displayed continuous cyclic softening.Notably,the alloy demonstrated reduced LCF life under conditions of-80℃and various strain amplitudes.The fatigue life model based on the total strain energy was developed and proven to be more accurate in predicting fatigue life under diverse LCF conditions.Furthermore,the combined kinematic/isotropic hardening constitutive model exhibited excellent performance in simulat-ing hysteresis loops of the alloy,with corresponding calibration errors all below 14%.Additionally,fatigue fracture surfaces under various LCF conditions consistently exhibited prominent cleavage fracture char-acteristics,and the final fracture zone at-80℃showed increased surface roughness.Finally,the cyclic softening mechanisms were found to be dependent on LCF conditions.The debonding of the interface be-tween the T1 phases and the Al matrix was identified as the primary cyclic softening mechanism under conditions of-20℃&0.6%and-80℃&0.6%.Moreover,the cyclic softening effect under-80℃&1.0%was closely associated with localized shearing of T1 phases.Under-20℃&1.0%,a more pronounced cyclic softening behavior was observed,which was primarily attributed to the continuous shearing of T1 phases.
基金financial support from the Equipment Pre-research Project(51312030507).
文摘This study investigates the fatigue crack propagation mechanism of a new high-strength and high-tough Ti-Mo-Cr-V-Nb-Al titanium alloy with three types of microstructures(basketweave structure,lamellar structure,and bimodal structure)through fatigue crack propagation rate tests and fatigue threshold value tests.The resistance of the alloy to fatigue crack propagation was found to be closely correlated with the morphology and distribution ofαparticles,as evidenced by microscopic examination of fracture surfaces and analysis of crack propagation paths.The primaryαparticles demonstrated superior resistance to crack propagation compared to the secondaryαparticles.The basketweave structure showed exceptional resistance to fatigue crack propagation at all stages.The lamellar structure mainly resists long crack propagation during rapid propagation,and its threshold value is the lowest,which makes it easy to produce microcrack propagation.On the contrary,the bimodal structure has the highest threshold value among the three,so its resistance to short crack growth is more excellent,but it has the highest crack growth rate in the higher stress intensity factor range.Theαparticles in the three microstructures also undergo rotational motion relative to the force axis during fatigue crack propagation,thereby adjusting the uneven stress distribution betweenα/βphases through slip behavior and further coordinating deformation.
基金Financial support from the Fundamental Research Funds for the Central Universities(ZJ2022-003,JG2022-27,J2020-060,and J2021-060)Sichuan Province Engineering Technology Research Center of General Aircraft Maintenance(GAMRC2021YB08)the Young Scientists Fund of the National Natural Science Foundation of China(No.52105417)is acknowledged.
文摘To overcome the challenges of limited experimental data and improve the accuracy of empirical formulas,we propose a low-cycle fatigue(LCF)life prediction model for nickel-based superalloys using a data augmentation method.This method utilizes a variational autoencoder(VAE)to generate low-cycle fatigue data and form an augmented dataset.The Pearson correlation coefficient(PCC)is employed to verify the similarity of feature distributions between the original and augmented datasets.Six machine learning models,namely random forest(RF),artificial neural network(ANN),support vector machine(SVM),gradient-boosted decision tree(GBDT),eXtreme Gradient Boosting(XGBoost),and Categorical Boosting(CatBoost),are utilized to predict the LCF life of nickel-based superalloys.Results indicate that the proposed data augmentation method based on VAE can effectively expand the dataset,and the mean absolute error(MAE),root mean square error(RMSE),and R-squared(R^(2))values achieved using the CatBoost model,with respective values of 0.0242,0.0391,and 0.9538,are superior to those of the other models.The proposed method reduces the cost and time associated with LCF experiments and accurately establishes the relationship between fatigue characteristics and LCF life of nickel-based superalloys.
基金supported by the National Key Research and Development Program of China(Grant No.2021YFC2800600)the National Natural Science Foundation of China(Grant No.52071203).
文摘Polymethyl methacrylate(PMMA)has the advantages of good transparency,corrosion resistance and light weight and can be used as the preferred material for pressure-resistant cabins of fully transparent submersibles.In this study,based on the fracture mechanics method,a calculation method for estimating the residual fatigue life of a PMMA manned cabin is proposed by improving the small-time scale fatigue crack growth rate model.This improved model is verified by the experimental data of the PMMA material.Then,through the Weibull and Gumbel combined distribution functions,the fatigue load spectrum suitable for the fully transparent manned cabin is fitted according to the dive data.A parametric analysis of the residual fatigue life of the fully transparent manned cabin under various initial crack sizes and dwell time is conducted,yielding valuable results.This study aims to increase the safety of fully transparent pressure-resistant cabins and offer insights for fatigue analysis of underwater structures utilizing PMMA materials.
