Fatigue Parameters Research Articles

Fatigue reliability evaluation for impellers with consideration of multi‐source uncertainties using a WOA‐XGBoost surrogate model

AbstractWhen using Monte Carlo simulation involving repeated finite element analysis (FEA) to perform fatigue reliability evaluation for an impeller, a variety of uncertainties should be considered to ensure the comprehensiveness of fatigue predictions. These uncertainties include the aleatory uncertainty from the geometric, material and load condition, and epistemic uncertainty from the parameters of the physics‐of‐failure (PoF) model to yield fatigue prediction. However, the latter uncertainty is often ignored in fatigue reliability analysis. And the reliability assessment will become computationally unaffordable and inefficient when there are many random variables involved, as an enormous amount of FEAs are demanded. To address this problem, a Whale Optimization Algorithm‐extreme gradient boosting (WOA‐XGBoost) surrogate model is developed, based on relatively few FEA results obtained using a Latin hypercube sampling (LHS). Its strengths lie in the interpretability of the design variables and effective determination of fine‐tuned hyperparameters. A case study on an impeller is conducted considering uncertainties from 11 input variables, where an efficient XGBoost model with an R2 greater than 0.93 on test set is established using 400 samples from practical FEAs. In addition, the importance analysis indicates that elasticity modulus and density play the greatest impact on the maximum strain, showing a combined importance of 82.3%. Furthermore, the reliability assessment results under fatigue parameter derived from the Median method tend to be more conservative compared to those obtained from the Seeger method.

Quasi-static and dynamic mechanical properties of a linoleic acid-modified, low-modulus bone cement for spinal applications.

Polymethylmethacrylate (PMMA) bone cement is extensively used in spinal procedures such as vertebroplasty and kyphoplasty, while its use in percutaneous cement discoplasty (PCD) is not yet widely spread. A main issue for both application sites, vertebra and disc, is the mismatch in stiffness between cement and bone, potentially resulting in adjacent vertebral fractures and adjacent segment disease. Tailoring the cement modulus using additives is hence an interesting strategy. However, there is a lack of data on the tensile and tension-compression fatigue properties of these cements, relevant to the newly researched indication of PCD. A commercial PMMA cement (VS) was modified with 12%vol of linoleic acid (VSLA) and tested for quasi-static tensile properties. Additionally, tension-compression fatigue testing with amplitudes ranging from +/-5MPa to +/-7MPa and +/-9MPa was performed, and a Weibull three-parameter curve fit was used to calculate the fatigue parameters. Quasi-static testing revealed a significant reduction in VSLA's Young's Modulus (E=581.1±126.4MPa) compared to the original cement (E=1478.1±202.9MPa). Similarly, the ultimate tensile stress decreased from 36.6±1.5MPa to 11.6±0.8MPa. Thus, VSLA offers improved compatibility with trabecular bone properties. Fatigue testing of VSLA revealed that as the stress amplitude increased the Weibull mean number decreased from 3591 to 272 and 91 cycles, respectively. In contrast, the base VS cement reached run-out at the highest stress amplitude. However, the lowest stress amplitude used exceeds the pressures recorded in the disc in vivo, and VSLA displayed a similar fatigue life range to that of the annulus fibrosis tissue. While the relevance of fully reversed tension-compression fatigue testing can be debated for predicting cement performance in certain spinal applications, the results of this study can serve as a benchmark for comparison of low-modulus cements for the spine. Further investigations are necessary to assess the clinical feasibility and effectiveness of these cements.

Assessment of the effectiveness of binder fatigue, rheology and chemistry parameters in evaluating cracking resistance in high RAP mixtures modified with recycling agents

The utilization of Reclaimed Asphalt Pavement (RAP) in pavement construction has gained prominence as a sustainable approach to reduce material costs and environmental effect. However, a significant challenge associated with increased RAP incorporation lies in the potential fracture distress caused by the aged binder. The purpose of this study is to assess the cracking performance of asphalt mixtures incorporating three levels of recycled materials (30% RAP, 50% RAP, and 30% RAP along with 5% Reclaimed Asphalt Shingles (RAS)). Three softening oils were employed to improve the cracking performances at two aging levels. Performance evaluations, including cracking performance assessments at intermediate and low temperatures, were carried out and compared with control mixtures. The findings of this study reveal that the incorporation of softening oils, as investigated herein, offers a viable means of producing asphalt mixtures featuring high RAP content while preserving performance comparable to that of a virgin mix. From a binder perspective, the Glover–Rowe (G–R) parameter and fatigue life at 10% strain level emerge as robust indicators for evaluating cracking resistance under conditions pertaining to intermediate and low temperatures.

Benefits of Individualized Training in Fatigued Patients with Multiple Sclerosis.

Chronic fatigue is the most common and debilitating symptom in people with multiple sclerosis (PwMS). Recently, exercise has been proven to alleviate chronic fatigue and improve physical functions. Tailoring the training intervention to the potential fatigue causes could optimize the beneficial effects of training on fatigue. The objective of this study was to compare the effectiveness of an individualized (IND) versus a traditional (TRAD) exercise intervention in reducing chronic fatigue. Twenty-nine PwMS with high chronic fatigue were randomly assigned to 12 wk of either a TRAD or IND exercise intervention. TRAD comprised aerobic and resistance exercises according to the guidelines for PwMS. IND specifically addressed identified individual weaknesses. Participants visited the laboratory before and after training for the following assessments: patient-reported outcomes (fatigue, quality of life, depression questionnaires), incremental cycling test (peak oxygen uptake (V̇O 2peak )), and cycling fatigue test (maximal voluntary contraction, rating of perceived exertion). Similar improvements in fatigue, depression, and quality of life were observed between groups ( P > 0.05). Compared with TRAD, IND induced a significant greater increase in V̇O 2peak (+21.0% ± 13.9% vs 6.8% ± 11.5%, P < 0.05) and a greater reduction in rating of perceived exertion at a given submaximal intensity (-30.3% ± 18.9% vs -12.1% ± 20.4%, P < 0.001), whereas maximal voluntary contraction increased similarly in both groups ( P > 0.05). Although tailored exercise improved similarly fatigue and other subjective parameters (depression, quality of life, sleep quality) compared with than traditional exercise intervention, prescribing an individualized intervention led to greater improvement in V̇O 2peak (but not maximal strength) and perception of effort. This may have positive functional consequences for patients.

Characterization of Asphalt Filler Mastics with Industrial By-Products as Fillers under the Coupled Effect of Aging and Moisture

An asphalt mix comprises asphalt binder and aggregates of different sizes (coarse and fine) and filler. Even with a smaller share, filler plays a crucial role in the performance of asphalt-filler mastics. The study is motivated by the growing need to preserve natural resources and aims to investigate the utilization of four different industrial by-products/wastes (electric arc furnace slag filler, basic oxygen furnace slag filler, tire pyrolysis char filler, and plastic pyrolysis char filler, and one conventional natural stone aggregate filler (NSAF) in asphalt-filler mastics. Four conditioning environments were used to characterize the chemo-rheological properties of the mastics formulated by these five different fillers: unaged, long-term aged, freeze-thaw, and freeze-thaw of long-term aged mastics. To understand the significance of filler attributes in the filler-asphalt mastic performance, a correlation between various filler characteristics (specific surface area, Rigden voids, methylene blue value, and hydrophilic coefficient) and the mastic properties (multiple stress creep and recovery, linear amplitude sweep, binder yield energy test, and Fourier transform infrared spectroscopy) was also attempted. The fatigue life and elastic recovery of the mastics were negatively affected by the combined effects of aging and moisture. The filler characteristics showed a negligible-to-low association with fatigue parameters and a good correlation with rutting performance. The use of these industry co-products/by-products as fillers is supported by the superior rutting and fatigue performance of steel slag and pyrolytic char fillers compared with the traditional NSAF.

Exploring the nexus between fatigue, body composition, and muscle strength in hemodialysis patients

BackgroundFatigue is a relatively prevalent condition among hemodialysis patients, resulting in diminished health-related quality of life and decreased survival rates. The purpose of this study was to investigate the relationship between fatigue and body composition in hemodialysis patients.MethodsThis cross-sectional study included 92 patients in total. Fatigue was measured by Functional Assessment of Chronic Illness Therapy – Fatigue (FACIT-F) (cut-off ≤ 34). Body composition was measured based on quantitative computed tomography (QCT), parameters including skeletal muscle index (SMI), intermuscular adipose tissue (IMAT), and bone mineral density (BMD). Handgrip strength was also collected. To explore the relationship between fatigue and body composition parameters, we conducted correlation analyses and binary logistic regression.ResultsThe prevalence of fatigue was 37% (n = 34), abnormal bone density was 43.4% (n = 40). There was a positive correlation between handgrip strength and FACIT-F score (r = 0.448, p < 0.001). Age (r = − 0.411, p < 0.001), IMAT % (r = − 0.424, p < 0.001), negatively associated with FACIT-F score. Multivariate logistic regression analysis shows that older age, lower serum phosphorus, higher IMAT% are associated with a high risk of fatigue.ConclusionThe significantly increased incidence and degree of fatigue in hemodialysis patients is associated with more intermuscular adipose tissue in paraspinal muscle.

Short-Term Panax Ginseng Extract Supplementation Reduces Fasting Blood Triacylglycerides and Oxygen Consumption during Sub-Maximal Aerobic Exercise in Male Recreational Athletes.

Ginseng, a popular herbal supplement among athletes, is believed to enhance exercise capacity and performance. This study investigated the short-term effects of Panax ginseng extract (PG) on aerobic capacity, lipid profile, and cytokines. In a 14-day randomized, double-blind trial, male participants took 500 mg of PG daily. Two experiments were conducted: one in 10 km races (n = 31) and another in a laboratory-controlled aerobic capacity test (n = 20). Blood lipid and cytokine profile, ventilation, oxygen consumption, hemodynamic and fatigue parameters, and race time were evaluated. PG supplementation led to reduced total blood lipid levels, particularly in triacylglycerides (10 km races -7.5 mg/dL (95% CI -42 to 28); sub-maximal aerobic test -14.2 mg/dL (95% CI -52 to 23)), while post-exercise blood IL-10 levels were increased (10 km 34.0 pg/mL (95% CI -2.1 to 70.1); sub-maximal aerobic test 4.1 pg/mL (95% CI -2.8 to 11.0)), and oxygen consumption decreased during the sub-maximal aerobic test (VO2: -1.4 mL/min/kg (95% CI -5.8 to -0.6)). No significant differences were noted in race time, hemodynamic, or fatigue parameters. Overall, PG supplementation for 2 weeks showed benefits in blood lipid profile and energy consumption during exercise among recreational athletes. This suggests a potential role for PG in enhancing exercise performance and metabolic health in this population.

Modeling of progressive high-cycle fatigue in composite laminates accounting for local stress ratios

A numerical framework for simulating progressive failure under high-cycle fatigue loading is validated against experiments of composite quasi-isotropic open-hole laminates. Transverse matrix cracking and delamination are modeled with a mixed-mode fatigue cohesive zone model, covering crack initiation and propagation. Furthermore, XFEM is used for simulating transverse matrix cracks and splits at arbitrary locations. An adaptive cycle jump approach is employed for efficiently simulating high-cycle fatigue while accounting for local stress ratio variations in the presence of thermal residual stresses. The cycle jump scheme is integrated in the XFEM framework, where the local stress ratio is used to determine the insertion of cracks and to propagate fatigue damage. The fatigue cohesive zone model is based on S-N curves and requires static material properties and only a few fatigue parameters, calibrated on simple fracture testing specimens. The simulations demonstrate a good correspondence with experiments in terms of fatigue life and damage evolution.

Thermal fatigue behaviors of thin-walled structures with holes: Experiments and phase field fracture modeling

The assessment of thermal fatigue behaviors of thin-walled structures with holes is a challenging task. A novel experimental approach was designed to test the thermal fatigue behaviors of thin-walled structures with holes. The experiments were conducted under three test conditions (300–850/950/1000 ℃) to investigate the behaviors of crack initiation and early propagation. The cyclic temperature loading exhibits high-transient and wide-ranging characteristics, enabling the construction of a non-uniform transient temperature field in the heating step. A thermal fatigue phase field model was developed for elastoplastic solids, and thermal fatigue fracture modeling and life prediction were performed. The phase field effectively reproduces crack morphology, and the experimental results closely match the simulation results when fatigue parameters are properly selected. Raising the upper limit of temperature will significantly diminish thermal fatigue life, accelerate crack growth, and induce a broader range of material damage. The temperature gradient in the heating step enhances the cyclic plastic behavior at the edge of the hole, significantly amplifying the detrimental impact of thermal fatigue.

A comprehensive methodology to estimate the fatigue life of S-shaped integral squeeze film damper

The Integral Squeeze Film Damper (ISFD) finds widespread application in various rotating machinery, such as gas turbines, turbochargers, and high-speed rotors, to dampen vibrations and improve operational stability. This study presents a comprehensive methodology to predict the fatigue life of an Integral Squeeze Film Damper (ISFD) by combining Low Cycle Fatigue (LCF), High Cycle Fatigue (HCF) test, and Finite Element (FE) simulations. An S-shaped spring specimen is designed and tested under high-cycle fatigue loading to develop the stress amplitude versus the number of the cycles curve. LCF tests are performed to obtain fatigue parameters, and a Chaboche kinematic hardening model is employed for cyclic plasticity FE simulations. FE analysis of the ISFD is conducted to establish its dynamic characteristics, aiding in identifying critical locations based on maximum von Mises stress. The integration of local stress–strain states from FE simulations with experimental fatigue parameters is carried out to predict fatigue life of ISFD. The validity of the methodology is confirmed through experimental and stress analyses, providing valuable insights for optimizing the fatigue performance of ISFD components.

Combined Effects of Breathing Exercise and Core Strength Training on Fatigue, Abdominal Strength, and Cardiovascular Fitness among Subjects with Mechanical Nonspecific Lumbago Using Tele-physiotherapy: A Randomized Clinical Trial

Abstract Background: Lumbago is derived from the word “lumbar region.” This pain in the lower back/lumbar region is addressed low back pain (LBP). It is considered a major health issue causing disability, and associated with increased fatigue level, decreased abdominal strength, and poor cardiovascular fitness in the affected population. Objectives of the Study: Isolate and configure combined effect of breathing exercise and core strengthening training on fatigue, abdominal strength, and cardiovascular fitness in mechanical nonspecific lumbago subjects using tele-physiotherapy. Methods: A two-group online randomized control trial was conducted involving 60 participants. The duration of the study stretched for 4 weeks. Subjects recruited in accordance with the inclusion and exclusion criteria were split into two groups, i.e., experimental and control groups. The experimental group performed core strength training and breathing exercises, whereas the control group performed only core strength training. Before exercise and at the end of each week fatigue, abdominal strength, and VO2max of the subjects were measured and evaluated. Results: Results from the present study concluded significant improvement within each group fatigue, abdominal strength (P &lt; 0.05). However, no between groups difference was observed for VO2max (P &gt; 0.05). Pain intensity perceived by the patients was improved in the group subjected to combined intervention involving core strengthening and breathing exercises as compared to the control group. Conclusion: The study proposed a significant effect of breathing exercise along with core strength training on parameters of fatigue, abdominal strength, and cardiovascular fitness in subjects with lumbago.

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.

Analysis of strength, durability, stability, and fatigue parameters of furniture doors and drawers using engineering design method

Mechanical behavior properties were investigated for cabinet-type cabinet doors in kitchen furniture and drawer bottoms and joints used as storage areas under load in accordance with relevant standards (BS EN 16122). In the first stage, values physical and mechanical for particle board (PB) and medium-density fiberboard (MDF) were determined. According to the test results in the second stage, it was determined that the doors assembled using a torque of 1.3 N/m in the door tests were less deformed than those assembled with 0.63 N/m. According to the finite element analysis and real test results carried out in the final stage, it has been determined that the vertical loading analysis applied on the doors coincides with the real experiments by 85%, horizontal loading by 84%, and slam shut by 50%. The doors didn’t pass the final stage durability test in real experiments, and the analysis results revealed that the deformation areas were the same as for real experiment. In the drawers; strength 85%, displacement 84%, and slam shut 94% overlap are represented. The drawers completed the durability test in real experiments, and in the analysis, it was determined that the deformation that occurred under high stresses was in the same areas.

Pilot facial feature recognition and fatigue classification method under high exposure environment

To improve the recognition efficiency of pilot fatigue detection in high exposure environment, a facial feature recognition and fatigue classification method for pilots is proposed. Firstly, the high exposure images are pre-processed with frequency domain light normalization; secondly, a human face detector is trained based on YOLOv5s network model and detects the face, eyes and mouth; again, the fatigue feature values of eyes and mouth are obtained by fusing PERCLOS fatigue detection algorithm; finally, a fatigue classifier is built by RBF-ELM neural network and the fatigue parameters of eyes, mouth and yawning The fatigue parameters of the eye, mouth and yawn features were input to the classifier for fatigue classification. The experimental results show that the fatigue detection speed of the proposed method is up to 310 FPS when computed with GPU, which has higher recognition rate and better robustness compared with the classical PCA, CNN and DCT methods. The method can effectively improve the accuracy of pilot facial feature recognition and eye localization in high exposure environment, and has high practicality for non-contact pilot fatigue detection.

A comprehensive evaluation of conventional methods for estimation of fatigue parameters of steels from their monotonic properties

A number of conventional and machine learning-based methods for the estimation of strain-life fatigue parameters from monotonic properties have been proposed in the literature and new ones are continuously being developed. With the development of new steels having improved properties such as higher ultimate strength, selecting appropriate estimation method becomes both increasingly difficult and important. In this study, according to the proposed detailed evaluation methodology, 10 conventional estimation methods have been evaluated regarding their accuracy and applicability for estimation of low- and high-cycle fatigue lives of unalloyed, low-alloy and high-alloy steels which were further divided into low- and high-strength subgroups. For this purpose, detailed, fully populated material dataset was assembled, including monotonic properties, cyclic stress–strain, and strain-life fatigue parameters of 75 unalloyed steels, 104 low-alloy steels and 44 high-alloy steels. With separate analyses, averaging of evaluation results was avoided and more detailed and precise ratings of individual methods were obtained. Complete material data and full results of the evaluations are made available in the paper which may further facilitate development and objective evaluations of new estimation methods and other predictive models.

Uncertainty quantification in multiaxial fatigue life prediction using Bayesian neural networks

In practical engineering scenarios, unforeseen failures may result in significant costs and risks. Assessing the uncertainty related to multiaxial fatigue life prediction is crucial for engineering applications. However, establishing a reliable multiaxial fatigue life prediction model remains challenging due to uncertainties in physical models, material properties, and measurement data. This paper proposes an effective Bayesian Neural Network (BNN) model for quantifying the uncertainty in multiaxial fatigue life prediction. Fatigue parameters in the multiaxial fatigue life prediction model are used as inputs for the BNN. The BNN method utilizes No-U-turn Sampler (NUTS) and Automatic Differentiation Variational Inference (ADVI) to address the inference problem in the model and perform life predictions for unknown non-proportional loading paths and different materials. Validation using experimental data from six different materials confirms the effectiveness of the BNN model. Experiments show that the performance of BNN models is beneficial in most cases compared to classical ML models, assessed through different error standards, statistical tests, Taylor diagrams, uncertainty analysis, and scatter index analysis. The proposed method provides a clear understanding of the uncertainty in multiaxial fatigue life prediction, offering a promising approach for simulating fatigue life under multiaxial loading in engineering applications.

Effect of nano-TiO2 on physical and rheological properties of asphalt cement

Abstract In recent years, nano-modified asphalt has gained significant attraction from researchers in the design of asphalt pavement fields. The recently discovered Titanium dioxide nanoparticles (TiO2) are among the most exciting and promising nanomaterials. This study examines the effect of 1, 3, 5, and 7% of nano-TiO2 by weight of asphalt on some of its rheological and hardened properties. The experimental study included physical and rheological properties. The asphalt penetration, softening point, ductility, and rotational viscometer tests indicate that 5% nano-TiO2 is the ideal amount to be added to bitumen as a modifier. The study of the rotating viscosity test showed that the addition of nano-TiO2 helped to increase viscosity and lessen bituminous sensitivity. Rutting factor in terms of G*/sin δ indicated the addition of 3 to 7% of nano-TiO2 increased the rutting resistance of asphalt against higher temperatures and promoted performance grade by about one grade at 3% and two grades at a range of 5–7% this suggests that nano-TiO2 increased the stiffness of the asphalt and leading to enhance the rutting performance of asphalt. While fatigue parameter, G*.sin δ shows that as nanocontent increases, higher stiffness at 5 and 7% of TiO2 content leads to an increase in complex modulus and a decrease in fatigue parameter. Higher creep stiffness and higher m-values were noted at low temperatures as nano increases in asphalt binder, increasing stiffness and decreasing the m-value at −6 and 12°C. As a result, using 5% nano-TiO2 will improve asphalt’s physical properties and enhance asphalt anit-rutting and fatigue resistance.

Optimization of human-machine interface for fatigue driving problem

Amidst rapid motorization, the surge in serious traffic accidents has raised concerns about the significant contribution of fatigued driving to road safety. However, the current vehicle-machine interface for fatigue driving reminder is relatively simplistic and plays a weak role. This study aims to optimize the functionality of traditional in-vehicle HMIs by exploring the key factors of human-computer interaction (HCI) and developing targeted user interfaces to effectively alert and reduce driver fatigue. A quantitative analysis based on previous experimental data is conducted to model the correlation between interface design factors (such as simplicity and feedback clarity) and physical fatigue parameters. An integrated user interface with fatigue alerts, rest area navigation, driver assistance, air conditioning settings, and voice control modules is proposed. Compared to the traditional interface, the improved user interface is evaluated in simulated driving conditions using an A/B experiment. The new user interface is expected to demonstrate improved effectiveness in relieving driver fatigue by providing clear visual, audio and haptic feedback. This research contributes a structured methodology for applying HCI principles to optimize in-vehicle interface design for mitigating driver fatigue, providing a framework to inform future interface development and enhance road safety.

Monitoring modifiable injury risk factors over an in-season mesocycle in semi-professional female field hockey players

ObjectiveThis study aimed to determine changes of modifiable injury risk factors and fatigue parameters during a mesocycle (4 months of the competitive season) in semi-professional female field hockey players (Spanish 2nd Division).MethodsFourteen female field hockey players (age: 22.6 ± 4.9 years) participated in the study over 4 months of the competitive season (September–December 2019). The players were tested each month for their: maximal isometric knee flexion, hip adduction, and abduction muscle strength; passive straight leg raise and ankle dorsiflexion range of motion (ROM); countermovement jump height; and perceptual fatigue (through a perceived well-being questionnaire).ResultsStatistical differences were reported in isometric knee flexion torque in the dominant and non-dominant limb (p = < 0.001, ηp2 = 0.629,0.786 respectively), non-dominant isometric hip abductors torque (p = 0.016, ηp2 = 0.266) and isometric hip adductors torque in dominant and non-dominant limbs (p = < 0.001, ηp2 = 0.441–546). Also, significant differences were reported in the straight leg raise test (p = < 0.001, ηp2 = 0–523, 0.556) and ankle dorsiflexion (p = 0.001, ηp2 = 0.376, 0.377) for the dominant and non-dominant limb respectively. Finally, the jump height measured showed significant differences (p = <.001, ηp2 = 0.490), while no differences were reported in perceived well-being parameters (p = 0.089–0.459).ConclusionIncrements in isometric muscle strength and fluctuations in ROM values and vertical jumping capacity are reported over an in-season mesocycle (i.e., 4 months of the competitive season). This information can be used to target recovery strategies to make them more efficient.

Coupling effect of non‐relaxing and high temperature on fatigue properties of carbon‐black filled isoprene rubber

AbstractThis paper presents an extensive experimental investigation on fatigue properties of carbon‐black filled isoprene rubber under complex loadings. A basic life prediction model taking strain energy density as fatigue parameter is first proposed based on fatigue crack growth tests and uniaxial tension fatigue tests under relaxing loads at room temperature. A database of fatigue life including relaxing and non‐relaxing is established through a great number of fatigue tests under five temperatures. Based on the database, two empirical parameters, that is, temperature factor (NRT/NHT) and life reinforcement factor (Re), are introduced to quantitatively characterize the coupling effects of high temperature and non‐relaxing loads on fatigue life. The fatigue mechanisms under different conditions are compared via wide‐angle x‐ray diffraction tests and postmortem analysis. It reveals that the weakening of life reinforcement at high temperatures is closely related to the strain induced crystallization behavior of rubber.