Fatigue Strength Research Articles

Standardized Boesenbergia pandurata Extract Prevents Dexamethasone-Induced Muscle Atrophy and Dysfunction in C57BL/6 Mice.

Muscle atrophy, characterized by diminished muscle mass and impaired function, poses a substantial global health concern. Boesenbergia pandurata (Roxb.) Schltr., commonly known as fingerroot, possesses a variety of advantageous activities, including anti-inflammatory, antioxidant, antibacterial, and anticancer effects. However, there are currently no preclinical studies available that explore the potential of B. pandurata extract (BPE) to mitigate muscle atrophy. In this study, we aimed to explore the protective effects of BPE, standardized to panduratin A content, against muscle atrophy and its underlying molecular mechanisms in a dexamethasone-induced muscle atrophy mouse model. Compared with the dexamethasone group, BPE significantly restored muscle mass, muscle volume, muscle fiber cross-sectional area, grip strength, and exercise endurance. Additionally, BPE suppressed inflammatory responses by downregulating the expressions of nuclear factor kappa B and inflammatory cytokines while also enhancing antioxidant effects by increasing the expressions of antioxidant enzymes. Moreover, BPE promoted protein synthesis and muscle differentiation by stimulating the phosphatidylinositol 3-kinase/Akt/mammalian target of rapamycin signaling pathway. Furthermore, it suppressed myostatin expression and inhibited the expressions of E3 ubiquitin ligases by preventing the nuclear translocation of forkhead box O3a, thereby alleviating proteolysis. Overall, BPE effectively regulates unbalanced protein metabolism, suggesting its potential as a functional food ingredient for preventing muscle wasting diseases.

Influence of surface integrity on short crack growth behavior in HFMI-treated welded joints

AbstractThis study investigates the influence of surface integrity and the localized fatigue phenomena on the initiation and propagation of short fatigue cracks in high-frequency mechanical impact (HFMI)-treated welded joints. The treated surface region, characterized by a compressive residual stress field, smooth notch geometry, and work hardening layer, improves welded joints’ fatigue strength. However, how these surface conditions influence the fatigue damage process zone during short crack initiation and growth is not yet well known. Therefore, this study systematically investigates the influence of different surface characteristics on fatigue life modeling of HFMI-treated welded joints made of high-strength steel. This is achieved using a non-local continuum damage mechanics-based approach of crack growth and elastic–plastic finite element simulation, explicitly modeling treated surface conditions. The simulated fatigue life is first verified with experiments and then applied to various surface conditions. The simulation results show that most of the fatigue life is spent until a crack size of 0.2 mm. The compressive residual stress field greatly extends both short crack initiation and propagation life, with its degree of contribution highly dependent on loading history and residual stress change. The role of the work hardening layer is mainly concentrated on improving fatigue life during short crack initiation and the very beginning of short crack growth.

Wake-up free La-doped ZrO2 antiferroelectric capacitors

Abstract This study experimentally investigated La-doped ZrO2 (ZLO) antiferroelectric (AFE) capacitors. Significant polarization enhancement is demonstrated in ZLO antiferroelectric capacitors with the optimized La concentration. The ZLO antiferroelectric capacitors reveal superior performance even under a low-temperature process (< 400℃). Remarkably, without the post-metallization annealing (PMA), ZLO devices still possess excellent antiferroelectric properties, which is highly advantageous for back-end-of-line (BEOL) process. Further endurance testing shows that ZLO antiferroelectric devices could withstand the wake-up effect during cycling process, showcasing unexceptionable endurance (>1010 cycles). The results in this study opens new avenues for practical antiferroelectric applications and brings promise for their integration into advanced integrated circuits.

A Virtual Response Surface Strategy to Predict the Effects of Contouring on the Static and Fatigue Mechanical Behavior of Spinal Rods.

Spinal fixation techniques based on contoured spinal rods are well established to restore an adequate sagittal alignment; however, they often break due to fatigue loading because residual stresses arise while deforming the material and they significantly reduce rod fatigue strength. The present paper aims at developing a novel strategy based on Response Surfaces (RS) as surrogate reduced order models to accurately predict the key biomechanical parameters involved both during static spinal rod contouring and subsequent fatigue loading. Finite element (FE) models of different contouring methods are performed on a wide range of spinal rods to reproduce typical clinical scenarios. RSs based on polynomial equations are initially used to fit the collected FE data and relate input parameters of the process to outputs mechanical variables. Then, the RS approach is assessed and validated by comparison with extensive experimental observations from a variety of fatigue tests. The RS provides an accurate prediction of the output parameters of interest (R2 = 0.88-1), with an average relative error up to 9% compared to computationally demanding FE models. Fatigue outputs are correctly predicted both for breakages and survivals of rods, despite an average overestimation on the equivalent stress of 11%. The RS approach proves credible and accurate in predicting the experimental fatigue strength of contoured spinal rods. The proposed method could serve in clinical practice as an intraoperative virtual tool to support the decision-making process.

Effect of Elevated Temperature on Low Cycle Fatigue and Tensile Strength of 12Cr Ferritic Steel

Effect of Elevated Temperature on Low Cycle Fatigue and Tensile Strength of 12Cr Ferritic Steel

Effect of Exercise Intervention on Chemotherapy-Induced Peripheral Neuropathy Symptoms in Cancer Patients: A Meta-analysis.

Exercise has been widely used to improve chemotherapy-induced peripheral neuropathy symptoms in cancer patients in recent years; however, there is insufficient evidence to support the effectiveness of exercise intervention in cancer patients. This review aims to comprehensively evaluate the effectiveness of exercise intervention in the management of chemotherapy-induced peripheral neuropathy symptoms in cancer patients and to explore effective exercise intervention characteristics by comparing the effects of different exercise prescriptions. Ten databases were systematically searched from published up to May 2024. The studies that met the inclusion criteria were included. The risk of bias was assessed using the Cochrane Collaboration tool. The statistical analyses were performed in Stata 17.0. A total of 21 studies with 775 participants were included. The pooled results showed that exercise significantly reduced the severity of chemotherapy-induced peripheral neuropathy symptoms; relieved neuropathic pain; enhanced balance function, muscle strength, physical flexibility, and physical endurance; and improved the quality of life of cancer patients with chemotherapy-induced peripheral neuropathy, both compared with patients in the usual care group and with patients' baseline symptoms before exercise. However, no significant improvement in fear of falling was observed. Exercise is an effective way of managing chemotherapy-induced peripheral neuropathy symptoms. The patient's age, exercise cycles, and frequency can affect the effect of the intervention. Oncology nurses can significantly manage chemotherapy-induced peripheral neuropathy symptoms in cancer patients through exercise intervention. Further research is necessary to explore the most suitable characteristics of exercise intervention to achieve optimal intervention effectiveness.

Enhanced performance of self-selective RRAM devices in V/TaOx/Pt structure

Abstract The performance of resistive random-access memory devices with vanadium as the top electrode and different TaOx insulating layer is investigated in this paper. The results indicate that the VO2 oxide layer generated by the oxidation of the vanadium electrode can serve as inherent selector, without the need for additional series selectors required in conventional methods. A large amount of oxygen vacancy migration was limited in the double insulating layers, enabling the device to achieve stable Self-Selective resistive random-access memory performance. This indicated that the advantage of the double insulation layers lay in manipulating the migration of oxygenions and vacancies. Endurance tests showed no degradation over 103 cycles, and the device maintained stability after 20,000 pulse applications. The subthreshold swing of the selector was less than 42 mV/dec, and the switching time was less than 2 μs. This research presents a promising advancement in resistive random-access memory technology with potential for high-density memory integration and reliable performance.

Optimizing High Cycle Fatigue Predictions in Notched Al 7075-T6: An Analytical Approach to Rotating Bending Behavior

Fatigue strength is affected by discontinuities in specimens, such as notches, holes and cracks. In this study, cylindrical specimens of Al-70-75-T6 were used, both without notches and with notches at a depth of 0.2 mm and 1 mm at angles of 30°, 45° and 60°. High fatigue rotational bending tests were performed at a stress ratio of -1 and a machine frequency of 60 Hz, with bending stress amplitudes of 180 MPa, 220 MPa, 260 MPa and 340 MPa. To predict fatigue properties, such as fatigue stress concentration factors and fatigue life, an analytical model supported by cohesive stress measurements obtained with an advanced finite element model for ductile damage was used. The effective fatigue concentration factors (Kf) and notch sensitivity of the material were determined using the Peterson formula. SEM analysis was performed to obtain a comprehensive understanding of the fracture mechanism.The fatigue limit was determined to be 180 MPa over 5 million complete cycles and a strong correlation was found between notch angle and fatigue life, providing valuable data for the development of rational design tables. The elastic stress concentration factor was scarcely affected by variations in the angle of entry and showed almost identical values at all angles tested. The analytical model showed good agreement with the experimental results, with a deviation of about 4.25%. All failure modes exhibited ductile properties, with microcracking throughout the inner surface significantly influencing the failure mechanisms. Failure modes were analyzed to better understand the failure mechanisms of aluminum alloy under cyclic loading.

Effects of Pediatric Endurance and Limb Strengthening (PEDALS) Program Versus Lower Limb Strength Training in Diplegic Cerebral Palsy

Objective: To evaluate the comparative effects of pediatric endurance and limb strengthening (PEDALS) program versus lower limb strength training in diplegic cerebral palsy(CP). Methodology: It was a Randomized clinical trial and a sample of 24 cerebral palsy (CP) patients was drawn through a consecutive sampling technique. One group of 12 patients received the PEDALS program and other group B of 12 patients received lower limb strength training. Group A PEDALS program was applied for 30 minutes, 3 days/week for 12 weeks, total 36 session and Group B lower limb strength training was applied 6-8rep, 1-3sets for3 days/week for 12 weeks, total 36 session. Outcome was measured with GMFM-88, Six-minute walk test and goniometer pre and post treatment. Results: Mean age for both group were 9.95±2.21. Mean value for total GMFM score for Group A was 64.916±8.129 and mean value for Group B was 65.33±9.92 with p-value > 0.05. Mean value for six minute test for Group A was 199.58±13.55 and for Group B was 195.50±15.71 with p-value >0.05 and ROM for Group Aand Group B p-value>0.05. Conclusion: Result shows that PEDALS program as well as lower limb strength training is effective in improving endurance, gross motor function and ROM in diplegic CP. Keywords: Cerebral palsy, endurance, pediatric, strength, training.

Tibial Baseplate Microstructure Governs High Cycle Fatigue Fracture InVivo.

Previous studies report rare occurrences of tibial baseplate fractures following primary total knee arthroplasty (TKA). However, at a microstructural scale, it remains unclear how fatigue models developed invitro apply to fractures invivo. In this study, we asked: (1) do any clinical factors differentiate fracture patients from a broader revision sample; and (2) invivo, how does microstructure influence fatigue crack propagation? We identified three fractured tibial baseplates from an institutional review board exempt implant retrieval program. Then, for comparison, we collated clinical data from the same database for n = 2120 revision TKA patients with tibial trays. To identify mechanisms, we characterized fracture features using scanning electron and digital optical microscopy. Additionally, we performed cross sectional analysis using focused ion beam milling. The fracture cohort consisted of moderately to very active patients with increased implantation time (15.6 years) compared to the larger revision patient sample (5.1 years, p = 0.009). We did not find a significant difference in patient weight between the two groups (p = 0.98). Macroscopic fracture features aligned well with both previous retrieval analysis and invitro baseplate fatigue tests. On a micron scale, we identified striations on each baseplate, demonstrating fatigue as the fracture mechanism. Invivo fatigue fracture processes depended on both the alloy (Ti-6Al-4V vs. CoCrMo) and the microstructure of the alloy formed during manufacturing. For Ti-6Al-4V, the presence of equiaxed or acicular microstructure influenced the fatigue crack propagation, the latter arising from large prior β grains and a Widmanstatten microstructure, degrading fatigue strength. CoCrMo alloy fatigue cracks propagated linearly, crystallographically influenced by planar slip. However, we did not document any features of overload or fast fracture, suggesting a high cycle, low stress fatigue regime. Ultimately, the crack profiles we present here may provide insight into fatigue fractures of modern tibial baseplates.

Fatigue Strength Assessment of Structural Materials with Plasma Coatings

Fatigue Strength Assessment of Structural Materials with Plasma Coatings

On the Damping and Fatigue Characterization of Additively Manufactured Ti-6Al-4V

With the recent implementation of additively manufactured parts into industrial applications, there is a dire need for nondestructive evaluation methods to qualify if these components are fit for service due to their sensitivity to processing conditions. The Impulse Excitation Technique (IET) is applied to additively manufactured Ti-6Al-4V bending specimens to determine natural frequencies and damping properties in order to predict fatigue performance relative to specimens fabricated with different processing parameters. From the damping and natural frequency results, it was found that the specimens, fabricated with intentional underheating to induce lack of fusion defects, had the lowest damping value in the pristine condition and the highest natural frequency. For the three batches of specimens tested, it was determined that the lack of fusion specimens had the best fully-reversed bending fatigue performance with the highest fatigue limit (297 MPa) and longest fatigue lives as compared to the other two batches, implying a relation of decreased fatigue life with increased material damping in the pristine condition. The theory of the IET related to materials is presented with damping and fatigue results, as well as microstructural analysis and fractography of three specimens batches fabricated with different processing parameters.

Dynamic behavior of piled jacket offshore wind turbines based on integrated aero-servo-hydro-SSI-OWT model

Jacket foundation is typically the preferred choice for Offshore Wind Turbines (OWTs) erected in water depth varying from 40 m to 80 m. In this paper, an integrated dynamic analysis model is designed to study the coupling between aerodynamics, servodynamics, hydrodynamics, soil-structure interaction for piled jacket OWTs. The performances of the AeroDyn and ServoDyn modules are verified by FAST, showcasing their applicability under deterministic and stochastic environmental conditions. The OWT dynamic responses, especially for t-z modeling, stress-transfer mechanism and structural fatigue damage, are subsequently studied. The overall deformation of the jacket calculated by the nonlinear elastic t-z curve in the API guideline, is overwhelmed by the t-z curve formulated using bounding surface plasticity framework, due to the ignorance of the loading history effect. Accompanied by a “compressed-released-recompressed” stress-transfer process, the downwind tube would experience high stress level, hence necessitating more attention in the ultimate limit state design of piled jacket structure. Otherwise, the upwind tube seems to be more decisive to the fatigue limit state design of piled jacket structure, owing to severe fluctuation in structural stress caused by a “tensed-released-re-tensed” stress-transfer tendency.

Reliability Of Maximum Heart Rate Estimation Equations In Athletes In The Field Football Base Category

The objective of this study was to verify the reliability of the HRmax prediction equations proposed by Fox, Tanaka and Nikolaidis in field football athletes who belong to the youth categories of a club in the first division of Brazilian league. One hundred and sixty-four players, aged between 14 and 20, took part in this study. In order to determine the athletes' HRmax (bpm), Yo-Yo Endurance Test Level 1 was used and defined as the highest value achieved during the test. Data were expressed as mean, standard deviation (SD) of the mean, minimum and maximum values.Independent Student's t-test and Pearson's correlation coefficient were used in statistical analyses. The results showed that none of the three available equations (Fox, Tanaka and Nikolaidis) provide accurate HRmax values in a sample of youth football players, underestimating or overestimating HRmax values. The equation that provided the most accurate HRmax was the Nikolaidis equation. This result is probably due to the fact that this equation was developed based on an example of a football player.

The Single Leg Bridge Test Does Not Measure Isolated Hamstring Endurance in Healthy Men.

The Single Leg Bridge Test (SLBT) is commonly described as a measure of 'hamstring endurance'. Nevertheless, the relationship between the SLBT score and isolated hamstring endurance remains uncertain. This study aimed to investigate the correlation between SLBT scores and isolated hamstring endurance in healthy men. Additionally, the study aimed to assess the correlation between the limb symmetry index obtained from the SLBT and hamstring endurance test results. Cross-sectional study. Forty healthy and physically active men were evaluated at the research laboratory on two separate occasions, with a minimum interval of 48 hours between visits. During each visit, participants performed either the single-leg balance test (SLBT) or the hamstring endurance test on an isokinetic dynamometer, which involved 30 concentric knee flexion repetitions performed at maximum intensity, with an angular velocity of 120°/s and a range of motion of 90°. Correlations were analyzed between SLBT scores and hamstring fatigue indexes provided by peak torque and work outcomes. The SLBT score (27±7 reps) demonstrated no significant correlation with isolated hamstring endurance, as measured by isokinetic peak torque (52±9%; p=0.737, r=-0.038) or work (57±9%; p=0.489, r=0.078). Likewise, the limb symmetry index obtained from the SLBT (99±12%) did not significantly correlate with index from the hamstring endurance test: peak torque (107±26%; p=0.540, r=-0.100) and work (102±18%; p=0.849, r=0.031). The SLBT does not appear to be a suitable tool for measuring isolated hamstring endurance in healthy men. 3.

Are Dental Prophylaxis Protocols Safe for CAD-CAM Restorative Materials? Surface Characteristics and Fatigue Strength

The surface of dental materials is exposed to various prophylaxis protocols during routine dental care. However, the impact of these protocols on the functional properties of the material’s surface remains unclear. This study investigates the influence of different dental prophylaxis protocols on the surface properties and their effect on the mechanical performance of CAD-CAM restorative materials. Discs (Ø = 15 mm, thickness = 1.2 mm) were fabricated from resin composite (RC, Tetric CAD), leucite-reinforced (LEU, IPS Empress CAD), lithium disilicate (LD, IPS e.max CAD), and zirconia ceramics (ZIR, IPS e.max ZirCAD MT). The materials were subjected to six prophylactic treatments: untreated (CTRL), prophylactic paste fine (PPF), prophylactic paste coarse (PPC), pumice stone (PS), air abrasion with sodium bicarbonate jet (BJ), and ultrasonic scaling (US). Biaxial flexural fatigue tests, along with fractographic, roughness, and topographic analyses, were conducted. No significant changes in fatigue strength were observed for RC, LD, and ZIR under any prophylaxis protocols. However, LEU subjected to BJ treatment exhibited significantly reduced fatigue strength (p = 0.004), with a 22% strength reduction compared to the monotonic test and substantial surface alterations. Surface roughness analyses revealed increased roughness for RC treated with PPF, PPC, and PS compared to CTRL (p < 0.05), while LD exhibited decreased roughness following PPF, PS, and US treatments (p < 0.05). In ZIR, only the BJ protocol increased roughness (p = 0.001). In conclusion, dental prophylaxis protocols do not significantly affect the mechanical strength of RC, LD, and ZIR materials, thus allowing any protocol to be used for these materials. However, for LEU ceramics, the BJ protocol should be avoided due to its effect of reducing fatigue strength and damaging the surface.

Fatigue fracture behaviors and damage evolution of coal samples treated with drying–wetting cycles investigated by acoustic emission and nuclear magnetic resonance

Constructing pumped-storage power stations using underground reservoirs in mines offers a promising method for large-scale energy storage. Watertight coal pillars have the potential to destabilize under the mine-shock cyclic dynamic loading and the drying–wetting cycles (DWCs). Understanding the fatigue damage mechanism and failure precursors in watertight coal pillars under cyclic dynamic loading disturbances in overburdened rock strata has become challenging. This study investigated the fatigue fracture behavior and precursor information of coal samples under acoustic emission (AE) monitoring over 1–7 DWC times. We analyzed the effects of DWC and fatigue cycles on the dynamic parameters and AE response, investigated crack spatial extension behaviors and the tensile-shear cracking evolution law, and analyzed the fatigue damage evolution law and failure precursor with energy and b-value. The results demonstrated that fatigue loading produced a strengthening effect on the DWC coal samples, and DWC promoted plastic softening damage to the specimens and increased the percentage of the elastic phase. The average dynamic fatigue strength and life of the specimens decreased exponentially under 7 DWC times. The average dynamic axial stiffness decreased by 15.67 %, the axial deformation increased by 6.1 × 10−4 in a single cycle, and the dynamic elasticity modulus of the fatigue damage instant decreased by 8.86 %. The greater the number of DWC, the smaller the b-value and the larger the fluctuation amplitude at fatigue failure of the specimen. A large short-term increase or decrease in the b-value can be regarded as a precursor to fatigue failure. This study provides a reference for the stability monitoring and forewarning of underground pumped-storage facilities.

Very-High-Cycle Fatigue Behaviors for Bearing Steel Microstructural Transformation

It has been reported that the multiphase structure with martensite and a mixed structure obtained by the quenching and tempering of bearing steel shows high strength and ductility. However, there appears to be no study on the effects of very-high-cycle fatigue (VHCF) and ultrasonic nanocrystal surface modification (UNSM) of a new bearing steel required for the durability design of next-generation bearing steel. This study analyzed the characteristics of microstructure transformation associated with heat treatment cycles and studied and evaluated the fatigue strength characteristics by the UNSM. Fisheye cracks occur from small inclusions inside the specimen only in martensitic microstructure materials in the long-life range. And the characteristic of a double S-N curve in which the fatigue limit decreased in two stages appeared. However, fisheye cracks and double S-N curves did not appear in pearlite and mixed-structure materials.

Altered cervical proprioception and biomechanics in obstructive sleep apnea: a case-control study.

This study aimed to compare cervical proprioception and related biomechanical factors among patients with Obstructive Sleep Apnea (OSA) and asymptomatic controls. In this case-control study, polysomnography scores (apnea-hypopnea index-AHI) were examined to determine the disease severity of the OSA group. Also, we evaluated cervical proprioception by using a laser pointer to detect joint repositioning error sense in cervical rotational movements. Comparison statistics were also conducted for the cervical musculoskeletal variables such as range of motion (ROM) with bubble inclinometer, cranio-cervical (CVA), and thoracic posture (TKA) through photometric analysis, neck flexor muscle endurance test, and pain pressure thresholds of trapezius (PPT). This case-control study included 59 male participants: patients with OSA (n = 29; mean age = 49.10 years; mean BMI = 28.41kg/m2) and asymptomatic controls (n = 30; mean age = 49.73 years; mean BMI = 26.89 ± 3.60kg/m2). The mean AHI score was 26.06 events/hour, categorizing the severity of OSA as mild (31.03%), moderate (31.03%), and severe (37.94%). Patients with OSA demonstrated significantly poorer cervical proprioception compared to controls for both sides of cervical rotation with larger effect sizes (d:1.36-1.45; p < 0.05). Also, cervical ROM, CVA, TKA, neck flexor muscle endurance test, and PPT values were altered in the OSA group compared to the control group (p < 0.05). Impaired cervical proprioception may be a previously unrecognized factor associated with OSA. This finding has implications for understanding the mechanisms underlying cervical musculoskeletal changes in OSA and for developing potential new interventions or exercise designs targeting postural control.

Detail categories for the flange-to-web weld detail in corrugated web girders

Corrugated web girders have gained popularity in both buildings and bridges due to their efficient use of materials. Previous research work has demonstrated that stainless steel corrugated web offers a promising solution for composite road bridges. However, to utilize these girders Efficiently in bridges, it is crucial to understand their fatigue performance. Notably, EN1993–1-9 does not include a detail category for the flange-to-web weld detail in girders with corrugated webs made of either carbon or stainless steel. To address this gap, numerous tests have been conducted and reported in the literature on carbon steel girders with various corrugation geometries. This paper aims at deriving detail categories for the flange-to-web weld detail in girders with corrugated webs. As a first step, it focuses on carbon steel, compiling, analyzing, and evaluating 86 fatigue test results available in the literature. The results show that the corrugation angle is the most important geometric parameter influencing the fatigue strength of the studied details. Based on this work, the following detail categories are proposed for various corrugation angles: DC125 for angles smaller than 30°, DC112 for angles between 30° and 40°, DC100 for angles between 40° and 45°, and DC90 for angles between 45° and 60°. Furthermore, the impact of other influencing geometrical parameters, such as bend radius and flange thickness, on fatigue strength is explored. The risk for root cracking in the weld between the flange and corrugated web is also evaluated through effective notch stress analysis.