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Aluminum alloys are ideal lightweight structural materials for spacecraft, but they are susceptible to local corrosion during service. Herein, a systematic investigation is carried out to determine the fatigue behavior of 5B70 aluminum alloy under salt spray precorrosion. The mechanism of salt spray corrosion, fatigue life, crack propagation, and failure fracture mechanism of 5B70 aluminum alloy are studied. Under the salt spray corrosion, 5B70 aluminum alloy mainly undergoes pitting corrosion via a galvanic corrosion mechanism. After precorrosion, the formation of macroscopic fatigue cracks is accelerated, which significantly reduces its fatigue life. Fracture occurs due to single crack initiation and propagation under fatigue conditions. The fatigue crack tip undergoes a mixture of intergranular and transgranular modes, but mainly transgranular mode. Multiple strain localization phenomena occur during precorrosion fatigue, and corrosion pits on the surface provide a tortuous crack propagation path; the fatigue crack tip is mainly transgranular mode. [ABSTRACT FROM AUTHOR]

Fatigue fractures are increasingly recognized as a common issue, particularly among athletes and individualsengaged in repetitive physical activities. Timely and accurate diagnosis of these fractures is crucial foreffective treatment and prevention of further injuries. This review explores contemporary diagnostic methodsfor fatigue fractures, evaluating the available techniques along with their advantages and limitations.The advancements in diagnostic methods have led to more precise and effective ways to identify and treatthese injuries. By gaining a comprehensive understanding of these diagnostic methods, healthcare providerscan better equip themselves with effective strategies for diagnosing and treating fatigue fractures,ultimately improving patient outcomes and reducing the risk of long-term complications. Additionally, thisreview examines the underlying causes and risk factors associated with fatigue fractures. Understandingthe contributing factors is essential for implementing preventive measures and developing comprehensivetreatment plans. Current trends and future prospects in the field of fatigue fracture diagnostics are also discussed,highlighting potential advancements and innovations that may further enhance diagnostic accuracyand effectiveness. The authors of the publication hope that the review presented below will help expandknowledge about fatigue fractures, optimize its diagnostic process and improve medical care in Poland.

Cardiopulmonary resuscitation (CPR) is a life-saving technique used in emergencies when the heart stops beating, typically involving chest compressions and ventilation. Current adult CPR guidelines do not differentiate based on age beyond infancy and childhood. This oversight increases the risk of fatigue fractures in the elderly due to decreased bone density and changes in thoracic structure. Therefore, this study aimed to investigate the correlation and impact of factors influencing rib fatigue fractures for safer out-of-hospital manual cardiopulmonary resuscitation (OHMCPR) application. Using the finite element analysis (FEA) method, we performed fatigue analysis on rib cage models incorporating chest compression conditions and age-specific trabecular bone properties. Fatigue life analyses were conducted on three age-specific rib cage models, each differentiated by trabecular bone properties, to determine the influence of four explanatory variables (the properties of the trabecular bone (a surrogate for the age of the subject), the site of application of the compression force on the breastbone, the magnitude of applied compression force, and the rate of application of the compression force) on the fatigue life of the model. Additionally, considering the complex interaction of chest compression conditions during actual CPR, we aimed to predict rib fatigue fractures under conditions simulating real-life scenarios by analyzing the sensitivity and interrelation of chest compression conditions on the model's fatigue life. Time constraints led to the selection of optimal analysis conditions through the use of design of experiments (DOE), specifically orthogonal array testing, followed by the construction of a deep learning-based metamodel. The predicted fatigue life values of the rib cage model, obtained from the metamodel, showed the influence of the four explanatory variables on fatigue life. These results may be used to devise safer CPR guidelines, particularly for the elderly at a high risk of acute cardiac arrest, safeguarding against potential complications like fatigue fractures. [ABSTRACT FROM AUTHOR]

The effect of surface treatment using an electron beam is explored as a factor influencing the nature and the rate of fatigue fracture propagation in titanium nickelide samples undergoing cyclic stretching under a low-cycle loading regime before and after irradiation with low-energy high-current electron beam (L-EHCEB). A correlation is established between the stage of fatigue fracture propagation and the stage of forming deformation zones on the fracture surfaces in unirradiated and in irradiated samples. The surfaces of the samples are treated using the electron beam installation RITM-SP having the following parameters of electron beam: energy density ES = 3.7 J/cm2, pulse duration τ = 2.5 μs, number of pulses n = 5. The difference in propagation sequence of main fatigue fractures is revealed under cyclic stretching of unirradiated and irradiated titanium nickelide samples. Preferential mechanisms of quasi-static and fatigue fracture are established at various stages of fracture propagation. It is shown that LEHCEB treatment shifted both the onset of fatigue destruction of material and all the following stages by ΔN ≥ +3000, increasing, thereby, the cycling resistance of samples by a factor of ~1.5. The greatest impact of surface modification is observed at stage I of fatigue fracture propagation. At this stage, the low propagation rate of fatigue fractures in irradiated samples results in increasing the duration of the stage as compared with unirradiated samples. The conclusion is made that, in order to increase the resilience of titanium nickelide samples effectively using LEHCEB treatment, it is required to set up conditions to increase the number of cycles before the start of stage I and to maximize the duration of this stage. [ABSTRACT FROM AUTHOR]

One of the major disadvantages of band saws is their low durability. Breakages during the operation are mostly caused by fractures in notches between the blades of the band as a result of the fatigue phenomenon. The strength of the band saw blades is ensured if the assurance coefficient value is greater than the theoretically determined one. The value of the assurance coefficient of 2 is recommended. A schematic limit-amplitude diagram was used to calculate the durability of band saws. A formula for the estimation of the assurance coefficient was derived. It was used for the calculation of the assurance coefficients of the band saw blades manufactured in accordance with GOST 6532–77, which are applicable in dividing band saw machines. The resulting value of the assurance coefficient was 1.44. The value is extremely low for the band saws because it is much lower than required. Band saw blades should be sharpened regularly to ensure a long and reliable service life. It should be made not only to ensure the required sharpness of the blades but also to remove the defective layers in notches caused by fatigue phenomena. In the article, there are more recommendations for improving the durability of the blades of the band saws. The durability of a new type of band saw with curved aerostatic guides and hard alloy blades was evaluated. Its assurance coefficient was 2.4. Therefore, the machine can be operated reliably for a long time without regular treatment of the notches. Consequently, band saws have low durability due to their increased breakdown rate and low wear resistance. Hence, the costs of their purchase and treatment rise. Therefore, the results presented in the article are practically applicable. For citation: Prokofiev G.F., Kovalenko O.L. Fatigue Strength of Band Saws. Lesnoy Zhurnal = Russian Forestry Journal, 2023, no. 4, pp. 136–145. (In Russ.). https://doi.org/10.37482/0536-1036-2023-4-136-145

Copyright of Die Unfallchirurgie is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Cardiopulmonary resuscitation (CPR) is a life-saving technique used in emergencies when the heart stops beating, typically involving chest compressions and ventilation. Current adult CPR guidelines do not differentiate based on age beyond infancy and childhood. This oversight increases the risk of fatigue fractures in the elderly due to decreased bone density and changes in thoracic structure. Therefore, this study aimed to investigate the correlation and impact of factors influencing rib fatigue fractures for safer out-of-hospital manual cardiopulmonary resuscitation (OHMCPR) application. Using the finite element analysis (FEA) method, we performed fatigue analysis on rib cage models incorporating chest compression conditions and age-specific trabecular bone properties. Fatigue life analyses were conducted on three age-specific rib cage models, each differentiated by trabecular bone properties, to determine the influence of four explanatory variables (the properties of the trabecular bone (a surrogate for the age of the subject), the site of application of the compression force on the breastbone, the magnitude of applied compression force, and the rate of application of the compression force) on the fatigue life of the model. Additionally, considering the complex interaction of chest compression conditions during actual CPR, we aimed to predict rib fatigue fractures under conditions simulating real-life scenarios by analyzing the sensitivity and interrelation of chest compression conditions on the model’s fatigue life. Time constraints led to the selection of optimal analysis conditions through the use of design of experiments (DOE), specifically orthogonal array testing, followed by the construction of a deep learning-based metamodel. The predicted fatigue life values of the rib cage model, obtained from the metamodel, showed the influence of the four explanatory variables on fatigue life. These results may be used to devise safer CPR guidelines, particularly for the elderly at a high risk of acute cardiac arrest, safeguarding against potential complications like fatigue fractures.

Copyright of Die Radiologie is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Selection of an appropriate nickel–titanium (NiTi) rotary system is important for minimally invasive endodontic treatment, which aims to preserve as much root canal dentin as possible. This study aimed to evaluate selected mechanical properties and the root canal shaping ability of TruNatomy (TRN), a NiTi rotary system designed for minimally invasive endodontic shaping, in comparison with existing instruments: HyFlex EDM (HEDM), ProTaper Next (PTN), and WaveOne Gold (WOG). Load values measured with a cantilever bending test were ranked as TRN < HEDM < WOG < PTN (p < 0.05). A dynamic cyclic fatigue test revealed that the number of cycles to fracture was ranked as HEDM > WOG > TRN > PTN (p < 0.05). Torque and vertical force generated during instrumentation of J-shaped artificial resin canals were measured using an automated instrumentation device connected to a torque and vertical force measuring system; TRN exhibited smaller torque and vertical force values in most comparisons with the other instruments. The canal centering ratio for TRN was smaller than or comparable to that for the other instruments except for WOG at the apex level. Under the present experimental conditions, TRN showed higher flexibility and lower torque and vertical force values than the other instruments. [ABSTRACT FROM AUTHOR]

Objectives: This study assessed the fatigue lifetime of reduced-diameter implants placed in either bovine rib or polymer-based bone model., Methods: Bovine ribs were classified according to the criteria proposed by Lekholm and Zarb and were analyzed for bone fraction. Fourteen dental implants (3.25 mm in diameter × 15 mm in length) were placed in bovine ribs used as a bone model. They were subjected to resonance frequency analysis. Stainless steel loading hemisphere caps were bonded on the abutments position at 30-degree angle and with a moment arm of 11 mm. Accelerated life testing using the step-stress method was conducted at 2 Hz with a stress ratio of 0.1 until fracture on a servo-hydraulic load frames machine (MTS). Results were compared with those of a previous study wherein implants were placed in a polymer-based bone model. Fatigue lifetime statistics (characteristic lifetime and Weibull modulus) of physical specimens were estimated in a reliability analysis software (ALTA PRO). Fractured specimens were examined under an electron scanning microscope to determine the failure mode., Result: The implants exhibited high stability quotient values (75.07 ± 3.81). Implants placed in bovine ribs showed better data dispersion and longer fatigue lifetime than those placed in polymer-based bone models, with no significant difference between groups. All fractures occurred in the implant body near the bone level and were indicative of fatigue fractures., Significance: Bovine ribs appear to be a more suitable material for accelerated life testing than the polymer-based material because of better data dispersion., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Objectives: This study evaluated the effect of deep margin elevation (DME) and restorative materials (leucite-reinforced glass–ceramics [C] vs. indirect resin composite [R]) on the fatigue behavior and stress distribution of maxillary molars with 2-mm deep proximal margins restored with MOD inlay. Methods: Fifty-two extracted human third molars were randomly assigned into four groups (n = 13): C; DME + C; R; and DME + R. Inlays were fabricated in CAD-CAM and bonded to all teeth. The fatigue behavior was assessed with the stepwise stress test (10,000 cycles/step; step = 50 N; 20 Hz; initial load = 200 N). Fatigue failure loads and the number of cycles were analyzed with 2-way ANOVA and Tukey's test (p < 0.05) and Kaplan–Meier survival plots. The stress distribution was assessed with finite element analysis. The models were considered isotropic, linear, and homogeneous, and presented bonded contacts. A tripod axial load (400 N) was applied to the occlusal surface. The stress distribution was analyzed with the maximum principal stress criterion. Results: For fatigue, there was no difference for DME factor (p > 0.05). For the material factor, the load and number of cycles for failure were statistically higher in the R groups (p < 0.05). The finite element analysis showed that resin composite inlays concentrated more stress in the tooth structure, while ceramic inlays concentrated more stress in the restoration. Non-reparable failures were more frequent in the resin composite inlays groups. Conclusions: DME was not negative for fatigue and biomechanical behaviors. Resin composite inlays were more resistant to the fatigue test, although the failure mode was more aggressive. Clinical significance: DME does not impair mechanical behavior. Resin composite inlays failed at higher loads but with a more aggressive failure mode. [ABSTRACT FROM AUTHOR]

Copyright of Turkiye Klinikleri Journal of Dental Sciences is the property of Turkiye Klinikleri and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Selection of an appropriate nickel–titanium (NiTi) rotary system is important for minimally invasive endodontic treatment, which aims to preserve as much root canal dentin as possible. This study aimed to evaluate selected mechanical properties and the root canal shaping ability of TruNatomy (TRN), a NiTi rotary system designed for minimally invasive endodontic shaping, in comparison with existing instruments: HyFlex EDM (HEDM), ProTaper Next (PTN), and WaveOne Gold (WOG). Load values measured with a cantilever bending test were ranked as TRN < HEDM < WOG < PTN (p < 0.05). A dynamic cyclic fatigue test revealed that the number of cycles to fracture was ranked as HEDM > WOG > TRN > PTN (p < 0.05). Torque and vertical force generated during instrumentation of J-shaped artificial resin canals were measured using an automated instrumentation device connected to a torque and vertical force measuring system; TRN exhibited smaller torque and vertical force values in most comparisons with the other instruments. The canal centering ratio for TRN was smaller than or comparable to that for the other instruments except for WOG at the apex level. Under the present experimental conditions, TRN showed higher flexibility and lower torque and vertical force values than the other instruments.

Coronal T2-weighted MRI with fat suppression shows the bilateral upper tibia marrow edema(white arrow) significantly reduced range, a low signal line in the medullary cavity of the left upper tibia gradually disappeared(white arrowheads). COVID-19, quarantine, students, Fatigue fractures, Physician Assistant (PA) Keywords: Fatigue fractures; COVID-19; quarantine; students; Physician Assistant (PA) EN Fatigue fractures COVID-19 quarantine students Physician Assistant (PA) 186 188 3 06/03/22 20220601 NES 220601 To the editor: We write in response to the outstanding work of 'Comparison of pediatric sports fracture outcomes based on provider type', We want to add a type of fracture, Sports related fractures in children fatigue fractures after the COVID-19 quarantine in China, The lesion may easily be mistaken for a malignant tumor or growing pain due to its rapid growth and imaging findings, it should arouse the attention of clinical. [Extracted from the article]

Abstract Background Bone stress fractures are overuse injuries commonly encountered in sports and military medicine. Some fatigue fractures lead to morbidity and loss of active, physically-demanding training days. We evaluated the incidence, anatomical location, risk factors, and preventive measures for fatigue fractures in young Finnish male conscripts. Methods Five cohorts of 1000 men performing military service, classified according to birth year (1969, 1974, 1979, 1984, 1989), were analysed. Each conscript was followed for his full military service period (180 days for conscripts with rank and file duties, 270 days for those with special training, 362 days for officers and highly trained conscripts). Data, including physical activity level, were collected from a standard pre-information questionnaire and from the garrisons’ healthcare centre medical reports. Risk factor analysis included the conscripts’ service class (A, B), length of military service, age, height, weight, body mass index, smoking, education, previous diseases, injuries, and subjective symptoms, as well as self-reports of physical activity before entering the service using a standard military questionnaire. Results Fatigue fractures occurred in 44 (1.1%) of 4029 men, with an incidence of 1.27 (95% confidence interval: 0.92–1.70) per 1000 follow-up months, and mostly (33/44, 75%) occurred at the tibial shaft or metatarsals. Three patients experienced two simultaneous stress fractures in different bones. Most fatigue fractures occurred in the first 3 months of military service. Conscripts with fatigue fractures lost a total of 1359 (range 10–77) active military training days due to exemptions from duty. Conscripts reporting regular (> 2 times/week) physical activity before entering the military had significantly fewer (p = 0.017) fatigue fractures. Regular physical activity before entering the service was the only strong explanatory, protective factor in the model [IRR = 0.41 (95% CI: 0.20 to 0.85)]. The other measured parameters did not contribute significantly to the incidence of stress fractures. Conclusion Regular and recurrent high-intensity physical activity before entering military service seems to be an important preventive measure against developing fatigue fractures. Fatigue fractures should be considered in conscripts seeking medical advice for complaints of musculoskeletal pain, and taken into consideration in planning military and other physical training programs.

Background Reverse total shoulder arthroplasty (RSA) accounts for nearly one-third of shoulder arthroplasty utilization nationally. The complication rate has increased concurrently. Consensus is lacking regarding the incidence, etiology, and treatment of acromial or scapular spine fractures after RSA. The purpose of our study was to perform a systematic review of the literature to analyze the occurrence and outcomes of this complication. Methods The MEDLINE, Embase, Google Scholar, and Cochrane databases were queried in late 2017 for combinations of the words "acromial," "fracture," "reverse," "shoulder," and "arthroplasty." We included all studies that contained a clearly defined performance of RSA, acromial fracture(s) noted, and treatment (if any) and outcomes of treatment. The initial search yielded 50 studies; 32 met the inclusion criteria. Results Among 3838 RSAs, 159 acromial fractures were reported, for an overall incidence of 4.14%; the mean time to diagnosis from surgery was 9 months (range, 1.3-24 months). Treatments included nonoperative treatment in a sling or abduction brace in 139 cases and open reduction–internal fixation in 20. Regardless of treatment, patients reported inferior function after fracture compared with initially after RSA. Forward flexion was 95° (range, 30°-110°), abduction was 76° (range, 30°-180°), the Constant score was 63 (range, 59-67.5), and the American Shoulder and Elbow Surgeons score was 57 (range, 7-83); all values were reduced compared with patients without fractures. Conclusion This study suggests the occurrence of acromial fractures after RSA is a common event, with a rate of over 4%. These fractures correlate with worse postoperative outcomes regardless of treatment method; open reduction–internal fixation was not shown to be clinically superior despite a limited complication rate. Additional high-quality studies addressing acromial spine fracture after RSA are needed. [ABSTRACT FROM AUTHOR]

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Stress fractures belong to the group of atraumatic fractures. A low-impact and repetitive load is the underlying cause and no fracture would occur under physiological circumstances. The conventional X‑ray examination remains the initial imaging modality when a stress fracture is suspected. In contrast, magnetic resonance imaging (MRI) is the gold standard and is also used to rule out other pathological changes. Computed tomography (CT) should be included if the MRI findings are unclear. New techniques, such as dual energy computed tomography (DECT) and magnetic resonance bone imaging (MR bone) should be used more frequently in practice in the future and become increasingly more important for the correct diagnosis., (© 2023. The Author(s), under exclusive licence to Springer Medizin Verlag GmbH, ein Teil von Springer Nature.)

This article shows a method for inspection scheduling of structures made by additive manufacturing, derived from reliability function evaluations and overhaul inspection findings. The routine was an adaption of an existing method developed by the authors for welded components; in this latter case, the routine used a stochastic defect-propagation analysis for pores and lack of fusion defects of additive manufacturing process, instead of the weld liquation crack. In addition, the authors modified the specific stress-intensity factor for welded components to consider additive manufacturing-related material property variability, defect distributions, flaw-inspection capabilities, and component geometry. The proposed routine evaluated the failure rate and inspection intervals using the first-order reliability method (FORM + Fracture) to alleviate the computational cost of probabilistic defect-propagation analysis. The proposed method is one of the first applying reliability concepts to additive manufacturing (AM) components. This is an important milestone, since in 10 years, additive manufacturing is to be used for 30% of the components in aeroengines. This paper presents an example comparing the reliability and cost of a jet engine, with components either made by additive manufacturing or welded parts; in the process, the reliability AM-key features are found, and overhaul schedules of an airplane fleet made with AM components are defined. The simplicity and performance demonstrated in the comparison make the proposed method a powerful engineering tool for additive manufacturing assessment in aeronautics.

This paper presents the results of an experimental study conducted on technical aluminum alloy EN AW-2024-T3 specimens under multiaxial low-cycle-fatigue loading at elevated temperatures. An original experimental setup, consisting of a biaxial servo-hydraulic MTS 858 MiniBionix material testing system, Maytec resistance furnace, high-temperature MTS extensometer and hydraulic grips of original design, was used in tests. Tubular specimens were subjected to multiaxial fatigue loading, proportional and non-proportional (with phase shift), under isothermal conditions of the air atmosphere. Multiaxial tests were performed under combined axial-torsional loading. Fractography analysis were conducted on the tested samples, and crack initiation mechanism under conditions of multiaxial loads at elevated temperatures were identified. Obtained fatigue life values were analyzed, particularly from the perspective of the possibility of approximating them by means of simple relations. [ABSTRACT FROM AUTHOR]

Bone stress injuries is an umbrella term that encompasses repetitive microtraumatic events that accumulate to surpass the threshold of bone failure, which can range from bone marrow edema to frank stress fracture as the end point. Due to nonspecific clinical complaints and physical findings, imaging plays a central role in the diagnostic workup of these entities. Magnetic resonance imaging (MRI) is the most important imaging modality with a high sensitivity and specificity and allows for differential diagnosis of other diseases. Edema-sensitive with fat suppression and T1-weighted sequences are the core sequence types, and contrast-enhanced imaging-albeit displaying subtle fractures much more easily-is rarely necessary. Furthermore, MRI enables differentiation of injury severity, which has an impact on length of rehabilitation, therapeutic regimen, and the time to return to sports in athletes., (© 2023. The Author(s), under exclusive licence to Springer Medizin Verlag GmbH, ein Teil von Springer Nature.)

Stress fractures are frequently underdiagnosed and undertreated despite being common in sports. Early diagnosis is crucial; therefore, a high index of clinical suspicion is required. Complementary examinations are essential for diagnosis and follow-up. The authors report a clinical case of a young adult triathlon athlete referring mechanical pain in the rear left foot, with 2 weeks' progression. An earlier increase in daily training intensity was recorded. Complementary examinations confirmed a calcaneal fatigue fracture. Immobilization and no weight bearing were introduced for an initial period of 4 weeks, and the rehabilitation process was started. Progressive weight bearing was introduced between fourth and eighth weeks. Sports activity started at the 1 2th week. Boundaries to sports activity were eliminated by the 24th week, without pain or functional limitation. Repetitive overload to the heel and intense axial weight bearing in association to repetitive concentric/eccentric gastrocnemius contraction are related to calcaneal stress fracture, the second most common stress fracture in the foot. Calcaneal stress fractures can be adequately treated with activity modification, without casting or surgical intervention. When in the presence of bilateral stress fractures, metabolic and nutritional issues must be considered. The case report highlights the importance of sports medicine examination for detecting intrinsic and extrinsic fatigue fracture risk factors. [ABSTRACT FROM AUTHOR]

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Copyright of Acta Odontologica Turcica is the property of Acta Odontologica Turcica and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)