WorldWideScience

Sample records for high cancer-related fatigue

  1. Armodafinil in Reducing Cancer-Related Fatigue in Patients With High Grade Glioma | Division of Cancer Prevention

    Science.gov (United States)

    This randomized phase III trial studies armodafinil to see how well it works in reducing cancer-related fatigue in patients with high grade glioma. Armodafinil may help relieve fatigue in patients with high grade glioma. |

  2. High-Dose Asian Ginseng (Panax Ginseng) for Cancer-Related Fatigue: A Preliminary Report.

    Science.gov (United States)

    Yennurajalingam, Sriram; Reddy, Akhila; Tannir, Nizar M; Chisholm, Gary B; Lee, Richard Tsong; Lopez, Gabriel; Escalante, Carmen P; Manzullo, Ellen F; Frisbee Hume, Susan; Williams, Janet L; Cohen, Lorenzo; Bruera, Eduardo

    2015-09-01

    Cancer-related fatigue (CRF) is the most common and severe symptom in patients with cancer. The number and efficacy of available treatments for CRF are limited. The objective of this preliminary study was to assess the safety of high-dose Panax ginseng (PG) for CRF. In this prospective, open-label study, 30 patients with CRF (≥4/10) received high-dose PG at 800 mg orally daily for 29 days. Frequency and type of side effects were determined by the National Cancer Institute's Common Terminology Criteria for Adverse Events, version 4.0. Scores on the Functional Assessment of Chronic Illness Therapy-Fatigue (FACIT-F) scale, Edmonton Symptom Assessment System (ESAS), and Hospital Anxiety and Depression Scale (HADS) were assessed at baseline, day 15, and day 29. Global Symptom Evaluation (GSE) was assessed at day 29. Of the 30 patients enrolled, 24 (80%) were evaluable. The median age was 58 years; 50% were females, and 84% were white. No severe (≥grade 3) adverse events related to the study drug were reported. Of the 24 evaluable patients, 21 (87%) had an improved (by ≥3 points) FACIT-F score by day 15. The mean ESAS score (standard deviation) for well-being improved from 4.67 (2.04) to 3.50 (2.34) (P = .01374), and mean score for appetite improved from 4.29 (2.79) to 2.96 (2.46) (P = .0097). GSE score of PG for fatigue was ≥3 in 15/24 patients (63%) with median improvement of 5. PG is safe and improves CRF fatigue as well as overall quality of life, appetite, and sleep at night. Randomized controlled trials of PG for CRF are justified. © The Author(s) 2015.

  3. Cancer related fatigue syndrome in neoplastic diseases

    Directory of Open Access Journals (Sweden)

    Magdalena Franc

    2014-12-01

    Full Text Available Fatigue is one of the most important factors which has a considerable influence on treatment and the life quality of oncological patients. The fatigue syndrome is often diagnosed during cancer treatment and this syndrome is not related to the physical effort. Cancer related fatigue is a patient’s subjective, psychologically, physically and emotionally based feeling. It is disproportionate to patient’s daily activity. The pathogenesis of this syndrome remains still unknown. However, on the basis of various questionnaires, it is possible to test the disease’s complex nature. Cancer related fatigue causes deterioration of patient’s life along with lower motivation to struggle with the disease. It is thought that the factor which increases the incidence of cancer related fatigue is a long-term use of drugs such as opioids, benzodiazepine, and medicines containing codeine, tranquilizers, anxiolytics and antidepressants. On the basis of the results, one can choose an appropriate treatment method for cancer related fatigue such as rehabilitation, psychotherapy or public assistance. A great number of patients consider excessive fatigue a typical concomitant symptom in neoplastic disease; therefore, they do not report it. It is of a paramount importance to make patients aware of the fact that cancer related fatigue is a serious disease which can be treated.

  4. Cancer-Related Fatigue: a multidimensional approach

    NARCIS (Netherlands)

    P.J. de Raaf (Pleun)

    2013-01-01

    textabstractFatigue is experienced by cancer patients in all stages of the disease trajectory: from before diagnosis to years after completing treatment and also in advanced cancer. Fatigue has a greater negative influence on quality of life and daily activities than any other cancer-related symptom

  5. Cancer-related fatigue: central or peripheral?

    Science.gov (United States)

    Yavuzsen, Tugba; Davis, Mellar P; Ranganathan, Vinoth K; Walsh, Declan; Siemionow, Vlodek; Kirkova, Jordanka; Khoshknabi, Dilara; Lagman, Ruth; LeGrand, Susan; Yue, Guang H

    2009-10-01

    To evaluate cancer-related fatigue (CRF) by objective measurements to determine if CRF is a more centrally or peripherally mediated disorder, cancer patients and matched noncancer controls completed a Brief Fatigue Inventory (BFI) and underwent neuromuscular testing. Cancer patients had fatigue measured by the BFI, were off chemotherapy and radiation (for more than four weeks), had a hemoglobin level higher than 10 g/dL, and were neither receiving antidepressants nor were depressed on a screening question. The controls were screened for depression and matched by age, gender, and body mass index. Neuromuscular testing involved a sustained submaximal elbow flexion contraction (SC) at 30% maximal level (30% maximum elbow flexion force). Endurance time (ET) was measured from the beginning of the SC to the time when participants could not maintain the SC. Evoked twitch force (TF), a measure of muscle fatigue, and compound action potential (M-wave), an assessment of neuromuscular-junction transmission were performed during the SC. Compared with controls, the CRF group had a higher BFI score (Pcontrols, P<0.05). This indicated less muscle fatigue. There was a greater TF (P<0.05) at the end of the SC, indicating greater central fatigue, in the CRF group, which failed to recruit muscle (to continue the SC), as well as the controls. M-Wave amplitude was lower in the CRF group than in the controls (P<0.01), indicating impaired neuromuscular junction conduction with CRF unrelated to central fatigue (M-wave amplitude did not change with SC). These data demonstrate that CRF patients exhibited greater central fatigue, indicated by shorter ET and less voluntary muscle recruitment during an SC relative to controls.

  6. Altered resting brain connectivity in persistent cancer related fatigue

    Directory of Open Access Journals (Sweden)

    Johnson P. Hampson

    2015-01-01

    Full Text Available There is an estimated 3 million women in the US living as breast cancer survivors and persistent cancer related fatigue (PCRF disrupts the lives of an estimated 30% of these women. PCRF is associated with decreased quality of life, decreased sleep quality, impaired cognition and depression. The mechanisms of cancer related fatigue are not well understood; however, preliminary findings indicate dysfunctional activity in the brain as a potential factor. Here we investigate the relationship between PCRF on intrinsic resting state connectivity in this population. Twenty-three age matched breast cancer survivors (15 fatigued and 8 non-fatigued who completed all cancer-related treatments at least 12 weeks prior to the study, were recruited to undergo functional connectivity magnetic resonance imaging (fcMRI. Intrinsic resting state networks were examined with both seed based and independent component analysis methods. Comparisons of brain connectivity patterns between groups as well as correlations with self-reported fatigue symptoms were performed. Fatigued patients displayed greater left inferior parietal lobule to superior frontal gyrus connectivity as compared to non-fatigued patients (P < 0.05 FDR corrected. This enhanced connectivity was associated with increased physical fatigue (P = 0.04, r = 0.52 and poor sleep quality (P = 0.04, r = 0.52 in the fatigued group. In contrast greater connectivity in the non-fatigued group was found between the right precuneus to the periaqueductal gray as well as the left IPL to subgenual cortex (P < 0.05 FDR corrected. Mental fatigue scores were associated with greater default mode network (DMN connectivity to the superior frontal gyrus (P = 0.05 FDR corrected among fatigued subjects (r = 0.82 and less connectivity in the non-fatigued group (r = −0.88. These findings indicate that there is enhanced intrinsic DMN connectivity to the frontal gyrus in breast cancer survivors with persistent

  7. Supervised exercise reduces cancer-related fatigue: a systematic review

    Directory of Open Access Journals (Sweden)

    José F Meneses-Echávez

    2015-01-01

    Full Text Available Question: Does supervised physical activity reduce cancer-related fatigue? Design: Systematic review with meta-analysis of randomised trials. Participants: People diagnosed with any type of cancer, without restriction to a particular stage of diagnosis or treatment. Intervention: Supervised physical activity interventions (eg, aerobic, resistance and stretching exercise, defined as any planned or structured body movement causing an increase in energy expenditure, designed to maintain or enhance health-related outcomes, and performed with systematic frequency, intensity and duration. Outcome measures: The primary outcome measure was fatigue. Secondary outcomes were physical and functional wellbeing assessed using the Functional Assessment of Cancer Therapy Fatigue Scale, European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire, Piper Fatigue Scale, Schwartz Cancer Fatigue Scale and the Multidimensional Fatigue Inventory. Methodological quality, including risk of bias of the studies, was evaluated using the PEDro Scale. Results: Eleven studies involving 1530 participants were included in the review. The assessment of quality showed a mean score of 6.5 (SD 1.1, indicating a low overall risk of bias. The pooled effect on fatigue, calculated as a standardised mean difference (SMD using a random-effects model, was –1.69 (95% CI –2.99 to –0.39. Beneficial reductions in fatigue were also found with combined aerobic and resistance training with supervision (SMD = –0.41, 95% CI –0.70 to –0.13 and with combined aerobic, resistance and stretching training with supervision (SMD = –0.67, 95% CI –1.17 to –0.17. Conclusion: Supervised physical activity interventions reduce cancer-related fatigue. These findings suggest that combined aerobic and resistance exercise regimens with or without stretching should be included as part of rehabilitation programs for people who have been diagnosed with cancer

  8. A coach in your pocket: on chronic cancer-related fatigue and physical behavior

    NARCIS (Netherlands)

    Wolvers, Maria Dorethea Jacoba

    2017-01-01

    Fatigue is a common and distressing long-term consequence of cancer. Chronic cancer-related fatigue affects work ability, hampers in maintaining social relations, and impacts patients’ well-being. Most treatments for chronic cancer-related fatigue focus to some extend on changing physical behavior,

  9. Effect of Meridian Massage for Cancer Related Fatigue

    Institute of Scientific and Technical Information of China (English)

    In sook Jeoung; Hwa-Seung Yoo

    2008-01-01

    The purpose of this study is to investigate the effectiveness of meridian massage in lessening the fatigue and improving both physical and mental quality of life of cancer patients. Settings and design: This study was conducted at the East-West Cancer Center at Daejeon University; Using a single-arm, waiting list and non-treatment control research design, we compared the results of control group and to that of the experimental group. Materials and methods: From July 2, 2007 to July 28, 2007, eighteen eligible cancer patients were recruited to participate in the experiment. Modified Chalder Fatigue Scale (CFS), Visual Analogue Scale (VAS) and active oxygen level were measured before and after treatment for both control and experimental groups. Lying on their back or stomach inside a room with a temperature of 18-2℃2, the patients received 30 minutes of meridian massages mainly around the trapezius muscles 5 times a week.Statistical analysis used: Data analysis was carried out using independent t-test, paired t-test and One-way ANOVA.Results: Data analysis of modified CFS showed statistically significant results for all groups between before and after treatment. Within CFS, results of physical and psychological analysis showed significant results for all groups except before and after no treatment and secondary treatment. In the analysis of VAS, the experimental group showed a greater decrease in score compared to that of the control group and the average difference was statistically significant (P<0.05). Although the results were not statistically significant (P>0.05), active oxygen levels for the control group showed little difference before and after no treatment (331.11 and 330.78, respectively) while the experimental group observed a decrease in active oxygen level before and after treatment (327.28 and 314.11, respectively). Conclusion: In conclusion, patients who received meridian massage showed decreased cancer related fatigue scores compared to the

  10. Low heart rate variability and cancer-related fatigue in breast cancer survivors

    OpenAIRE

    2014-01-01

    Cancer-related fatigue is a common and often long lasting symptom for many breast cancer survivors. Fatigued survivors show evidence of elevated inflammation, but the physiological mechanisms driving inflammatory activity have not been determined. Alterations in the autonomic nervous system, and particularly parasympathetic nervous system activity, are a plausible, yet understudied contributor to cancer-related fatigue. The goal of this study was to replicate one previous study showing an ass...

  11. Lower heart rate variability is associated with cancer-related fatigue in breast cancer survivors

    OpenAIRE

    2012-01-01

    Background : Fatigue is the most common and distressing symptom reported by breast cancer survivors and yet the pathophysiology of cancer-related fatigue remains largely unknown. Fatigue is associated with lower parasympathetic and higher sympathetic nervous system activity in non-cancer samples, but only one study has demonstrated this same relationship in breast cancer survivors. This study evaluates the relationship between fatigue and basal autonomic nervous system activity as measured by...

  12. A systematic review of complementary and alternative medicine interventions for the management of cancer-related fatigue.

    Science.gov (United States)

    Finnegan-John, Jennifer; Molassiotis, Alex; Richardson, Alison; Ream, Emma

    2013-07-01

    Fatigue, experienced by patients during and following cancer treatment, is a significant clinical problem. It is a prevalent and distressing symptom yet pharmacological interventions are used little and confer limited benefit for patients. However, many cancer patients use some form of complementary and alternative medicine (CAM), and some evidence suggests it may relieve fatigue. A systematic review was conducted to appraise the effectiveness of CAM interventions in ameliorating cancer-related fatigue. Systematic searches of biomedical, nursing, and specialist CAM databases were conducted, including Medline, Embase, and AMED. Included papers described interventions classified as CAM by the National Centre of Complementary and Alternative Medicine and evaluated through randomized controlled trial (RCT) or quasi-experimental design. Twenty studies were eligible for the review, of which 15 were RCTs. Forms of CAM interventions examined included acupuncture, massage, yoga, and relaxation training. The review identified some limited evidence suggesting hypnosis and ginseng may prevent rises in cancer-related fatigue in people undergoing treatment for cancer and acupuncture and that biofield healing may reduce cancer-related fatigue following cancer treatments. Evidence to date suggests that multivitamins are ineffective at reducing cancer-related fatigue. However, trials incorporated within the review varied greatly in quality; most were methodologically weak and at high risk of bias. Consequently, there is currently insufficient evidence to conclude with certainty the effectiveness or otherwise of CAM in reducing cancer-related fatigue. The design and methods employed in future trials of CAM should be more rigorous; increasing the strength of evidence should be a priority.

  13. Educational interventions for the management of cancer-related fatigue in adults.

    Science.gov (United States)

    Bennett, Sally; Pigott, Amanda; Beller, Elaine M; Haines, Terry; Meredith, Pamela; Delaney, Christie

    2016-11-24

    Cancer-related fatigue is reported as the most common and distressing symptom experienced by patients with cancer. It can exacerbate the experience of other symptoms, negatively affect mood, interfere with the ability to carry out everyday activities, and negatively impact on quality of life. Educational interventions may help people to manage this fatigue or to cope with this symptom, and reduce its overall burden. Despite the importance of education for managing cancer-related fatigue there are currently no systematic reviews examining this approach. To determine the effectiveness of educational interventions for managing cancer-related fatigue in adults. We searched the Cochrane Central Register of Controlled Trials (CENTRAL), and MEDLINE, EMBASE, CINAHL, PsycINFO, ERIC, OTseeker and PEDro up to 1st November 2016. We also searched trials registries. We included randomised controlled trials (RCTs) of educational interventions focused on cancer-related fatigue where fatigue was a primary outcome. Studies must have aimed to evaluate the effect of educational interventions designed specifically to manage cancer-related fatigue, or to evaluate educational interventions targeting a constellation of physical symptoms or quality of life where fatigue was the primary focus. The studies could have compared educational interventions with no intervention or wait list controls, usual care or attention controls, or an alternative intervention for cancer-related fatigue in adults with any type of cancer. Two review authors independently screened studies for inclusion and extracted data. We resolved differences in opinion by discussion. Trial authors were contacted for additional information. A third independent person checked the data extraction. The main outcome considered in this review was cancer-related fatigue. We assessed the evidence using GRADE and created a 'Summary of Findings' table. We included 14 RCTs with 2213 participants across different cancer diagnoses. Four

  14. Acupressure for persistent cancer-related fatigue in breast cancer survivors (AcuCrft): a study protocol for a randomized controlled trial

    National Research Council Canada - National Science Library

    Zick, Suzanna Maria; Wyatt, Gwen Karilyn; Murphy, Susan Lynn; Arnedt, J Todd; Sen, Ananda; Harris, Richard Edmund

    2012-01-01

    Despite high levels of clinically significant persistent cancer related fatigue in breast cancer survivors few treatments are currently available and most pose a significant burden on the part of the woman...

  15. Pilot crossover trial of Reiki versus rest for treating cancer-related fatigue.

    Science.gov (United States)

    Tsang, Kathy L; Carlson, Linda E; Olson, Karin

    2007-03-01

    Fatigue is an extremely common side effect experienced during cancer treatment and recovery. Limited research has investigated strategies stemming from complementary and alternative medicine to reduce cancer-related fatigue. This research examined the effects of Reiki, a type of energy touch therapy, on fatigue, pain, anxiety, and overall quality of life. This study was a counterbalanced crossover trial of 2 conditions: (1) in the Reiki condition, participants received Reiki for 5 consecutive daily sessions, followed by a 1-week washout monitoring period of no treatments, then 2 additional Reiki sessions, and finally 2 weeks of no treatments, and (2) in the rest condition, participants rested for approximately 1 hour each day for 5 consecutive days, followed by a 1-week washout monitoring period of no scheduled resting and an additional week of no treatments. In both conditions, participants completed questionnaires investigating cancer-related fatigue (Functional Assessment of Cancer Therapy Fatigue subscale [FACT-F]) and overall quality of life (Functional Assessment of Cancer Therapy, General Version [FACT-G]) before and after all Reiki or resting sessions. They also completed a visual analog scale (Edmonton Symptom Assessment System [ESAS]) assessing daily tiredness, pain, and anxiety before and after each session of Reiki or rest. Sixteen patients (13 women) participated in the trial: 8 were randomized to each order of conditions (Reiki then rest; rest then Reiki). They were screened for fatigue on the ESAS tiredness item, and those scoring greater than 3 on the 0 to 10 scale were eligible for the study. They were diagnosed with a variety of cancers, most commonly colorectal (62.5%) cancer, and had a median age of 59 years. Fatigue on the FACT-F decreased within the Reiki condition (P=.05) over the course of all 7 treatments. In addition, participants in the Reiki condition experienced significant improvements in quality of life (FACT-G) compared to those in

  16. Low heart rate variability and cancer-related fatigue in breast cancer survivors.

    Science.gov (United States)

    Crosswell, Alexandra D; Lockwood, Kimberly G; Ganz, Patricia A; Bower, Julienne E

    2014-07-01

    Cancer-related fatigue is a common and often long lasting symptom for many breast cancer survivors. Fatigued survivors show evidence of elevated inflammation, but the physiological mechanisms driving inflammatory activity have not been determined. Alterations in the autonomic nervous system, and particularly parasympathetic nervous system activity, are a plausible, yet understudied contributor to cancer-related fatigue. The goal of this study was to replicate one previous study showing an association between lower parasympathetic activity and higher fatigue in breast cancer survivors (Fagundes et al., 2011), and to examine whether inflammation mediates this association. Study participants were drawn from two samples and included 84 women originally diagnosed with early stage breast cancer prior to age 50. Participants completed questionnaires, provided blood samples for determination of interleukin (IL)-6 and C-reactive protein (CRP), and underwent electrocardiography (ECG) assessment for evaluation of resting heart rate variability (HRV), a measure of parasympathetic activity. Results showed that lower HRV was associated with higher fatigue (pcancer-related fatigue, but suggest that inflammation does not mediate this association in younger, healthy breast cancer survivors who are several years post-treatment. The autonomic nervous system merits additional attention in research on the etiology of cancer-related fatigue.

  17. Cancer-related fatigue shows a stable association with diurnal cortisol dysregulation in breast cancer patients.

    Science.gov (United States)

    Schmidt, Martina E; Semik, Johanna; Habermann, Nina; Wiskemann, Joachim; Ulrich, Cornelia M; Steindorf, Karen

    2016-02-01

    Fatigue is a major burden for breast cancer patients undergoing adjuvant therapy. Yet, its pathophysiology is still not well understood. Hypothesized mechanisms include dysregulations in the hypothalamic-pituitary-adrenal (HPA) axis, which may be reflected in alterations in the diurnal cortisol patterns. However, studies on the association between cortisol and fatigue during adjuvant cancer therapy are rare. We therefore assessed salivary cortisol at awakening, 0.5h post-awakening, noon, 5 pm and 10 pm/bedtime in 265 breast cancer patients undergoing adjuvant therapy at three timepoints. Cancer-related fatigue was assessed with the Fatigue Assessment Questionnaire (FAQ) covering the physical, affective, and cognitive fatigue dimensions. Multiple linear regression analyses were performed cross-sectionally at the three timepoints as well as longitudinally considering changes in cortisol and fatigue over time. The results showed that the physical dimension of cancer-related fatigue was significantly associated with increased evening cortisol levels and higher overall cortisol secretion. These associations were independent of depressive symptoms. Morning cortisol levels, the cortisol awakening response and the diurnal slope were not consistently associated with physical fatigue. Affective and cognitive fatigue showed no clear association with any of the cortisol parameters. In conclusion, the physical but not the affective or cognitive dimension of fatigue seems associated with cortisol dysregulations in breast cancer patients undergoing adjuvant therapy, characterized by an unaffected cortisol level in the morning but blunted decline to the evening level. Research focusing on disturbances of the cortisol rhythm and HPA dysregulations during and after cancer treatment may open new strategies to reduce cancer-related fatigue.

  18. Evidence of significant central fatigue in patients with cancer-related fatigue during repetitive elbow flexions till perceived exhaustion.

    Directory of Open Access Journals (Sweden)

    Bin Cai

    Full Text Available OBJECTIVE: To investigate whether fatigue induced by an intermittent motor task in patients with cancer-related fatigue (CRF is more central or peripheral. METHODS: Ten patients with CRF who were off chemo and radiation therapies and 14 age-matched healthy controls were enrolled. Participants completed a Brief Fatigue Inventory (BFI and performed a fatigue task consisting of intermittent elbow-flexion contractions at submaximal (40% maximal voluntary contraction intensity till self-perceived exhaustion. Twitch force was elicited by an electrical stimulation applied to the biceps brachii muscle. The relative degree of peripheral (muscle vs. central contribution to fatigue induced by the intermittent motor task (IMT was assessed using twitch force ratio (TF ratio defined as post IMT twitch force to pre IMT twitch force. The total number of trials (intermittent contractions and total duration of all trials performed by each subject were also quantified. RESULTS: BFI scores were higher (p < 0.001 in CRF than controls, indicating greater feeling of fatigue in CRF patients than controls. A significantly smaller number of trials and shorter total duration of the trials (p < 0.05 were observed in CRF than control participants. The TF ratio (0.81 ± 0.05 in CRF was higher (p < 0.05 compared with that of controls (0.62 ± 0.05, suggesting CRF patients experienced a significantly lower degree of muscle (peripheral fatigue at the time of perceived exhaustion. CONCLUSION: Consistent with prior findings for fatigue under submaximal sustained contraction, our results indicate that motor fatigue in CRF is more of central than peripheral origin during IMT. Significant central fatigue in CRF patients limits their ability to prolong motor performance.

  19. Low Recent Protein Intake Predicts Cancer-Related Fatigue and Increased Mortality in Patients with Advanced Tumor Disease Undergoing Chemotherapy.

    Science.gov (United States)

    Stobäus, Nicole; Müller, Manfred J; Küpferling, Susanne; Schulzke, Jörg-Dieter; Norman, Kristina

    2015-01-01

    Cancer patients, in general, suffer from anorexia hence diminished nutritional intake. In a prospective observational study, we investigated the impact of recent energy and protein intake on cancer-related fatigue and 6-month mortality in patients undergoing chemotherapy. Recent protein and energy intake was assessed by 24-h recall in 285 patients. Cancer-related fatigue was determined by Brief Fatigue Inventory, and fat free mass index (FFMI) was assessed with bioelectrical impedance analysis. Symptoms with the validated German version of European Organization for Research and Treatment of Cancer Quality of Life Core Questionnaire (30 questions) and 6-month mortality was documented. Risk factors of cancer-related fatigue and predictors of mortality were investigated with logistic regression analysis and stepwise Cox regression analysis, respectively. Low protein intake (protein intake emerged as the strongest contributor to cancer-related fatigue followed by nausea/vomiting, insomnia, and age. Reduced protein intake, male sex, number of comorbidities, and FFMI were identified as significant predictors for increased 6-month mortality. In conclusion, a low recent protein intake assessed by 24-h recall is associated with a more than twofold higher risk of cancer-related fatigue and 6-month mortality. Every effort should be taken to assess and guarantee proper nutritional intake in patients undergoing chemotherapy.

  20. The biology of cancer-related fatigue: a review of the literature.

    Science.gov (United States)

    Saligan, Leorey N; Olson, Karin; Filler, Kristin; Larkin, David; Cramp, Fiona; Yennurajalingam, Sriram; Sriram, Yennu; Escalante, Carmen P; del Giglio, Auro; Kober, Kord M; Kamath, Jayesh; Palesh, Oxana; Mustian, Karen

    2015-08-01

    Understanding the etiology of cancer-related fatigue (CRF) is critical to identify targets to develop therapies to reduce CRF burden. The goal of this systematic review was to expand on the initial work by the National Cancer Institute CRF Working Group to understand the state of the science related to the biology of CRF and, specifically, to evaluate studies that examined the relationships between biomarkers and CRF and to develop an etiologic model of CRF to guide researchers on pathways to explore or therapeutic targets to investigate. This review was completed by the Multinational Association of Supportive Care in Cancer Fatigue Study Group-Biomarker Working Group. The initial search used three terms (biomarkers, fatigue, cancer), which yielded 11,129 articles. After removing duplicates, 9145 articles remained. Titles were assessed for the keywords "cancer" and "fatigue" resulting in 3811 articles. Articles published before 2010 and those with samples articles for full-text review. Of the 75 articles, 28 were further excluded for not investigating the associations of biomarkers and CRF. Of the 47 articles reviewed, 25 were cross-sectional and 22 were longitudinal studies. More than half (about 70 %) were published recently (2010-2013). Almost half (45 %) enrolled breast cancer participants. The majority of studies assessed fatigue using self-report questionnaires, and only two studies used clinical parameters to measure fatigue. The findings from this review suggest that CRF is linked to immune/inflammatory, metabolic, neuroendocrine, and genetic biomarkers. We also identified gaps in knowledge and made recommendations for future research.

  1. Cancer-Related Fatigue in Women With Breast Cancer: Outcomes of a 5-Year Prospective Cohort Study.

    LENUS (Irish Health Repository)

    Goldstein, David

    2012-04-16

    PURPOSEProlonged and disabling fatigue is prevalent after cancer treatment, but the early natural history of cancer-related fatigue (CRF) has not been systematically examined to document consistent presence of symptoms. Hence, relationships to cancer, surgery, and adjuvant therapy are unclear. PATIENTS AND METHODSA prospective cohort study of women receiving adjuvant treatment for early-stage breast cancer was conducted. Women (n = 218) were enrolled after surgery and observed at end treatment and at 1, 3, 6, 9, and 12 months as well as 5 years. Structured interviews and self-report questionnaires were used to record physical and psychologic health as well as disability and health care utilization. Patients with CRF persisting for 6 months were assessed to exclude alternative medical and psychiatric causes of fatigue. Predictors of persistent fatigue, mood disturbance, and health care utilization were sought by logistic regression.ResultsThe case rate for CRF was 24% (n = 51) postsurgery and 31% (n = 69) at end of treatment; it became persistent in 11% (n = 24) at 6 months and 6% (n = 12) at 12 months. At each time point, approximately one third of the patients had comorbid mood disturbance. Persistent CRF was predicted by tumor size but not demographic, psychologic, surgical, or hematologic parameters. CRF was associated with significant disability and health care utilization. CONCLUSIONCRF is common but generally runs a self-limiting course. Much of the previously reported high rates of persistent CRF may be attributable to factors unrelated to the cancer or its treatment.

  2. The effects of a six-week supervised multimodal exercise intervention during chemotherapy on cancer-related fatigue

    DEFF Research Database (Denmark)

    Andersen, Christina; Rørth, Mikael; Ejlertsen, Bent

    2013-01-01

    Cancer related fatigue (CRF) is a common problem for cancer patients across diagnoses during chemotherapy and is associated with physical inactivity, lower functional level and lack of energy. Few RCT exercise intervention studies have included cancer patients undergoing chemotherapy. The objecti...... of this study is to evaluate whether a six-week supervised multimodal exercise intervention, adjunct to chemotherapy and standard care, can reduce the patient's CRF level.......Cancer related fatigue (CRF) is a common problem for cancer patients across diagnoses during chemotherapy and is associated with physical inactivity, lower functional level and lack of energy. Few RCT exercise intervention studies have included cancer patients undergoing chemotherapy. The objective...

  3. Alexithymia and cancer-related fatigue: a controlled cross-sectional study.

    Science.gov (United States)

    Gritti, Paolo; Lombardi, Salvatore; Nobile, Barbara; Trappoliere, Paola; Gambardella, Antonio; Di Caprio, Ester Livia; Resicato, Gianluca

    2010-01-01

    The study aims to investigate the alexithymia construct in patients with a recent or longtime diagnosis of cancer as well as in healthy people, and whether alexithymia and fatigue are linked in the mentioned groups. A first group, diagnosed less than 3 months previously (n = 63), and a second group whose cancer diagnosis dated back more than 30 months (n = 53), matched for sex, age, educational level and cancer site were assessed. Matched healthy controls (n = 50) were also evaluated. Alexithymia was assessed with the Toronto Alexithymia Scale-20, while fatigue was assessed with the Brief Fatigue Inventory. Alexithymia scores were higher in the recently diagnosed group than in the group with a longtime cancer diagnosis (t = 2.18, P < 0.05). Both groups had higher scores than controls (t = 4.3, P < 0.001; t = 2.01, P < 0.05). Alexithymic subjects were 45.6% in the recently diagnosed and 21.4% in the longtime diagnosed group (Chi(2) = 6.3, P < 0.05) and 18% in controls. Fatigue was more severe in patients with a longtime diagnosis compared with recently diagnosed patients (t = 7.079, P = 0.000). A weak but significant association between fatigue and alexithymia was found in recently diagnosed patients (r = 0.27.2; P < 0.05). Our study confirms that alexithymia scores are higher in cancer patients than in controls. The study suggests that alexithymia could be considered a dynamic reaction to illness in recently diagnosed patients, declining during subsequent phases. High fatigue rates in patients with a longtime diagnosis of cancer underline the role of the long course of illness in the perception of fatigue. The association between fatigue and alexithymia was weak in the recently diagnosed group and not significant in patients with a longtime diagnosis, in whom fatigue was an important complaint.

  4. Cancer-related Fatigue in Patients with Advanced Cancer Treated with Autonomic Nerve Pharmacopuncture.

    Science.gov (United States)

    Park, Ji-hye; Jeon, Hyung-jun; Kang, Hwi-joong; Jeong, In-Sook; Cho, Chong-kwan; Yoo, Hwa-seung

    2015-06-01

    The purpose of this study was to observe the effects of autonomic nerve pharmacopuncture (ANP) treatment on cancer-related fatigue (CRF) in patients with advanced cancer. This observational case study was conducted at the East West Cancer Center of Daejeon University's Dunsan Korean Medical Hospital. Two patients were observed. One patient was diagnosed with left thymic cancer metastatic to the left pleura. The other patient had terminal-stage cervical cancer with iliac bone and lumbar 5 metastases. We injected mountain ginseng pharmacopuncture (MGP) into acupoints alongside the spine (Hua-Tuo-Jia-Ji-Xue, EX B2). We examined the patients for CRF using the Korean version of the Revised Piper Fatigue Scale (RPFS-K), which is a self-assessment tool. The scores on the RPFS-K for both patients tended to decrease during the treatment. Laboratory findings, including hematological changes, were also checked. Liver and renal function tests showed that the treatment was safe. Although further large-population studies are necessary, this case study suggests that ANP has a favorable effect on CRF in patients with advanced cancer.

  5. Effect of whole course tracking model in responsibility system of high quality nursing service on cancer - related fatigue and sleep disorders of patients with cervical cancer after chemotherapy%责任制优质护理全程追踪模式对宫颈癌化疗后癌因性疲乏和睡眠障碍的影响

    Institute of Scientific and Technical Information of China (English)

    高静

    2015-01-01

    目的:探讨责任制优质护理全程追踪模式对宫颈癌患者化疗后癌因性疲乏和睡眠障碍的影响。方法:将84例宫颈癌化疗患者随机分为观察组和对照组各42例,对照组化疗期间实施常规护理,观察组化疗期间实施责任制优质护理全程追踪模式,干预前后应用癌因性疲乏量表、SPIEGEL 量表及简易健康量表(SF -36)对两组患者癌因性疲乏、睡眠障碍及生活质量进行评价。结果:观察组干预后癌因性疲乏评分显著低于对照组,SPIEGEL 量表总评分及各维度评分均高于对照组( P <0.05)。观察组干预后生理功能、生理职能、情感职能、社会功能、身体疼痛、活动、精神健康及总体健康评分显著高于对照组(P <0.05)。结论:责任制优质护理全程追踪模式能有效改善宫颈癌患者化疗后癌因性疲乏、睡眠质量障碍,提高患者生活质量。%Objective:To investigate the effect of whole course tracking model in responsibility system of high quality nursing service on cancer - related fatigue and sleep disorders of patients with cervical cancer after chemotherapy. Methods:84 cervical cancer patients with chemotherapy were randomly divided into the observation group and the control group(42 cases in each group). The conventional nursing care was taken during chemotherapy in the control group and the whole course tracking model in responsibility system of high quality nurs-ing service was carried out during chemotherapy in the observation group. The cancer - related fatigue scale,SPIEGEL scale and SF - 36 were used to evaluate cancer - related fatigue,sleep disorders and quality of life of the patients in the two groups before and after the inter-vention. Results:The scores of cancer - related fatigue were significantly lower in the observation group than those in the control group after the intervention and the total score of SPIEGEL and the score of each dimension

  6. Cancer-Related Fatigue: A Systematic and Meta-Analytic Review of Non-Pharmacological Therapies for Cancer Patients

    Science.gov (United States)

    Kangas, Maria; Bovbjerg, Dana H.; Montgomery, Guy H.

    2008-01-01

    Cancer-related fatigue (CRF) is a significant clinical problem for more than 10 million adults diagnosed with cancer each year worldwide. No "gold standard" treatment presently exists for CRF. To provide a guide for future research to improve the treatment of CRF, the authors conducted the most comprehensive combined systematic and meta-analytic…

  7. Effects of physical exercise during adjuvant breast cancer treatment on physical and psychosocial dimensions of cancer-related fatigue : A meta-analysis

    NARCIS (Netherlands)

    Van Vulpen, Jonna K.; Peeters, Petra H M; Velthuis, Miranda J.; van der Wall, Elsken; May, Anne M.

    2016-01-01

    Cancer-related fatigue has a multidimensional nature and complaints typically increase during adjuvant treatment for breast cancer. Physical exercise might prevent or reduce cancer-related fatigue. So far, no meta-analysis has investigated the effects of physical exercise on different dimensions of

  8. Sympathetic and parasympathetic activity in cancer-related fatigue: more evidence for a physiological substrate in cancer survivors.

    Science.gov (United States)

    Fagundes, Christopher P; Murray, David M; Hwang, Beom Seuk; Gouin, Jean-Philippe; Thayer, Julian F; Sollers, John J; Shapiro, Charles L; Malarkey, William B; Kiecolt-Glaser, Janice K

    2011-09-01

    Fatigue is a notable clinical problem in cancer survivors, and understanding its pathophysiology is important. This study evaluated relationships between fatigue and both sympathetic and parasympathetic nervous system activity in breast cancer survivors. Norepinephrine and heart rate variability (HRV) were evaluated at rest, as well as during and after a standardized laboratory speech and mental arithmetic stressor. The participants, 109 women who had completed treatment for stage 0-IIIA breast cancer within the past two years, were at least two months post surgery, radiation or chemotherapy, whichever occurred last. Women who reported more fatigue had significantly higher norepinephrine and lower HRV before and after the stressor than their less fatigued counterparts. Fatigue was not related to treatment or disease variables including treatment type, cancer stage, time since diagnosis, and time since treatment. Importantly, the relationship between HRV and cancer-related fatigue was sizeable. Based on research that has demonstrated characteristic age-related HRV decrements, our findings suggest a 20-year difference between fatigued and non-fatigued cancer survivors, raising the possibility that fatigue may signify accelerated aging. Furthermore, lower HRV and elevated norepinephrine have been associated with a number of adverse health outcomes; accordingly, fatigue may also signal the need for increased vigilance to other health threats.

  9. International Psychometric Validation of an EORTC Quality of Life Module Measuring Cancer Related Fatigue (EORTC QLQ-FA12).

    Science.gov (United States)

    Weis, Joachim; Tomaszewski, Krzysztof A; Hammerlid, Eva; Ignacio Arraras, Juan; Conroy, Thierry; Lanceley, Anne; Schmidt, Heike; Wirtz, Markus; Singer, Susanne; Pinto, Monica; Alm El-Din, Mohamed; Compter, Inge; Holzner, Bernhard; Hofmeister, Dirk; Chie, Wei-Chu; Czeladzki, Marek; Harle, Amelie; Jones, Louise; Ritter, Sabrina; Flechtner, Hans-Henning; Bottomley, Andrew

    2017-05-01

    The European Organisation for Research and Treatment of Cancer (EORTC) Group has developed a new multidimensional instrument measuring cancer-related fatigue to be used in conjunction with the quality of life core questionnaire (EORTC QLQ-C30). The module EORTC QLQ-FA13 assesses physical, cognitive, and emotional aspects of cancer-related fatigue. The methodology follows the EORTC guidelines for phase IV validation of modules. This paper focuses on the results of the psychometric validation of the factorial structure of the module. For validation and cross-validation confirmatory factor analysis (maximum likelihood estimation), intraclass correlation and Cronbach alpha for internal consistency were employed. The study involved an international multicenter collaboration of 11 European and non-European countries. A total of 946 patients with various tumor diagnoses were enrolled. Based on the confirmatory factor analysis, we could approve the three-dimensional structure of the module. Removing one item and reassigning the factorial mapping of another item resulted in the EORTC QLQ-FA12. For the revised scale, we found evidence supporting good local (indicator reliability ≥ 0.60, factor reliability ≥ 0.82) and global model fit (GFI t1|t2 = 0.965/0.957, CFI t1|t2 = 0.976/0.972, RMSEA t1|t2 = 0.060/0.069) for both measurement points. For each scale, test-retest reliability proved to be very good (intraclass correlation: R t1-t2 = 0.905-0.921) and internal consistency proved to be good to high (Cronbach alpha = .79-.90). Based on the former phase III module, the multidimensional structure was revised as a phase IV module (EORTC FA12) with an improved scale structure. For a comprehensive validation of the EORTC FA12, further aspects of convergent and divergent validity as well as sensitivity to change should be determined.

  10. Cancer-Related Fatigue in Patients With and Survivors of Hodgkin Lymphoma: The Impact on Treatment Outcome and Social Reintegration.

    Science.gov (United States)

    Behringer, Karolin; Goergen, Helen; Müller, Horst; Thielen, Indra; Brillant, Corinne; Kreissl, Stefanie; Halbsguth, Teresa Veronika; Meissner, Julia; Greil, Richard; Moosmann, Peter; Shonukan, Oluwatoyin; Rueffer, Jens Ulrich; Flechtner, Hans-Henning; Fuchs, Michael; Diehl, Volker; Engert, Andreas; Borchmann, Peter

    2016-12-20

    Purpose Cancer-related fatigue occurs frequently in patients with Hodgkin lymphoma (HL) and has a major impact on their quality of life. We hypothesized that severe fatigue (sFA) might have an impact on patients' treatment outcome and social reintegration. Methods Of 5,306 patients enrolled in the German Hodgkin Study Group's fifth generation of clinical trials in HL (HD13, HD14, and HD15; nonqualified and older [> 60 years] patients excluded), 4,529 provided data on health-related quality of life. We describe sFA (defined as a score ≥ 50 on the 0 to 100 scale from the European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire Core 30) before and up to 9 years after therapy and analyze its impact on treatment outcome and social reintegration. Results The proportion of patients reporting sFA was 37% at baseline and ranged from 20% to 24% during follow-up. Baseline sFA was associated with significantly impaired progression-free survival and a trend to impaired overall survival, which can be overcome in patients receiving highly effective HL therapies as applied in our fifth-generation trials. Our analysis revealed a significant negative association of sFA and employment in survivors: 5 years after therapy, 51% and 63% of female and male survivors, respectively, with sFA were working or in professional education, compared with 78% and 90% without sFA, respectively ( P reintegration during follow-up. This observation underscores the need to address fatigue as a significant diagnosis when treating patients with and survivors of cancer.

  11. Cancer-related fatigue management: evaluation of a patient education program with a large-scale randomised controlled trial, the PEPs fatigue study.

    Science.gov (United States)

    Bourmaud, A; Anota, A; Moncharmont, C; Tinquaut, F; Oriol, M; Trillet-Lenoir, V; Bajard, A; Parnalland, S; Rotonda, C; Bonnetain, F; Pérol, D; Chauvin, F

    2017-03-28

    To assess the efficacy of a patient educational program built according to guidelines that aims at reducing cancer-related fatigue (CRF). Randomised controlled trial, multicentre, comparing a patient education program, vs the standard of care. Patients were adult cancer outpatients with any tumour site. The primary outcome was fatigue severity assessed with a visual analogical scale (VAS), between the day of randomisation and week 7. Secondary outcomes were fatigue assessed with other scales, health-related quality of life, anxiety and depression. The time to fatigue severity deterioration was assessed. Analyses were performed in a modified intent-to-treat way, that is, including all patients with at least one baseline and 1 week 7 score. A total of 212 patients were included. Fatigue severity assessment was made on 79 patients in the experimental group and 65 in the control group. Between randomisation and week 7, the fatigue (VAS) improved by 0.96 (2.85) points in the experimental group vs 1.63 (2.63) points in the control group (P=0.15). No differences with the secondary outcomes were highlighted between two groups. No other factors were found to be associated with fatigue severity deterioration. Despite rigorous methodology, this study failed to highlight the program efficacy in fatigue reduction for cancer patients. Other assessment tools should be developed to measure the effect of the program on CRF and behaviour. The implementation of the program should also be explored in order to identify its mechanisms and longer-term impact.

  12. Cancer-related fatigue and depression in breast cancer patients postchemotherapy: Different associations with optimism and stress appraisals.

    Science.gov (United States)

    Levkovich, Inbar; Cohen, Miri; Pollack, Shimon; Drumea, Karen; Fried, Georgeta

    2015-10-01

    Symptoms of depression and cancer-related fatigue (CRF) are common among breast cancer patients postchemotherapy and may seriously impair quality of life (QoL). This study aimed to assess the relationship between depression and CRF in breast cancer patients postchemotherapy and to examine their relationships to optimism and to threat and challenge appraisals. Participants included 95 breast cancer patients (stages 1-3) 1 to 6 months after completion of chemotherapy. Patients submitted personal and medical details and completed the following: physical symptom questionnaires (EORTC QLQ-C30, and QLQ-BR23), a symptoms of depression questionnaire (CES-D), the Fatigue Symptom Inventory (FSI), the Life Orientation Test (LOT-R), and a stress appraisals questionnaire. We found levels of depression, CRF, and appraisals of cancer as a threat to bemoderate and levels of optimism and appraisals of cancer as a challenge to be high. Depression and CRF were positively associated. A multivariate regression analysis revealed that 51% of the CRF variancewas explained; physical symptoms and threat appraisal were significantly associated with CRF. A 67% of the CRF variance of depression was explained; challenge and threat appraisals were significantly associated with depression [corrected]. Although CRF and depression were often experienced simultaneously and both were found to be higher among individuals who gave higher appraisals of cancer as a threat, only depression was related to optimism and challenge appraisals, while CRF was related mainly to intensity of physical symptoms. The different pattern of associations between optimism and appraisals warrants further clinical attention as well as future study.

  13. THE APPROACH OF CANCER RELATED FATIGUE IN RHEABILITATION MEDICINE: PART I – MECHANISMS, SYMPTOMS, CLINICAL EVALUATION AND SCREENING

    Directory of Open Access Journals (Sweden)

    SALCA Amalia

    2015-05-01

    Full Text Available Cancer related fatigue (CRF is the most disabling and distressing symptom in cancer, throughout the whole history of the illness, including successfully treated cases. Rehabilitation medicine could have a positive impact on these patients’ outcomes, if well targeted. With these purpose, the rehabilitation clinician needs to correctly assess fatigue using standard, reliable scales. This review of articles and trials synthesizes the epidemiology, mechanics (including causes and effects, clinical presentation and means of assessment in CRF. CRF causes and mechanisms are not well known. Understanding them would provide specific targets to fatigue management. Clinical presentation is very variable, a wide range of features being found in literature. Poorly medical reports in assessing fatigue offer variable percentages of prevalence, inconsistent with patients’ daily burden due to CRF. There are many tools used to assess fatigue in clinical research and on them depends the percentages reported as fatigue prevalence. The hereby gathered information are useful in the approach of a patient that addresses to a rehabilitation clinician for CRF management.

  14. What is the best term in Spanish to express the concept of cancer-related fatigue?

    OpenAIRE

    Centeno-Cortes, C. (Carlos); Portela, M.A. (María Angustias); Carvajal,A; San-Miguel, T. (Teresa); Urdiroz, J. (Julia); Ramos, L.I. (Luis Isaac); Santiago, A

    2009-01-01

    Introduction: Fatigue is one of the most frequent symptoms in patients with cancer. No adequate term in Spanish has been defined to describe the English concept of fatigue. Aim: To identify the most suitable Spanish words that define the concept of fatigue and to check psychometric characteristics. Method: Consensus with professional experts on Spanish words that best suit the English concept of fatigue. A prospective study on oncologic patients was also undertaken, which included an ...

  15. Effects of aerobic exercise on cancer-related fatigue in breast cancer patients receiving chemotherapy: a meta-analysis.

    Science.gov (United States)

    Zou, Ling-Yun; Yang, Liu; He, Xiao-Ling; Sun, Ming; Xu, Jin-Jiang

    2014-06-01

    Increasing scientific evidences suggest that aerobic exercise may improve cancer-related fatigue in breast cancer patients, but many existing studies have yielded inconclusive results. This meta-analysis aimed to derive a more precise estimation of the effects of aerobic exercise on cancer-related fatigue in breast cancer patients receiving chemotherapy. The PubMed, CISCOM, CINAHL, Web of Science, Google Scholar, EBSCO, Cochrane Library, and CBM databases were searched from inception through July 1, 2013 without language restrictions. Crude standardized mean difference (SMD) with 95 % confidence interval (CI) was calculated. Twelve comparative studies were assessed with a total of 1,014 breast cancer patients receiving chemotherapy, including 522 patients in the aerobic exercise group (intervention group) and 492 patients in the usual care group (control group). The meta-analysis results revealed that the Revised Piper Fatigue Scale (RPFS) scores of breast cancer patients in the intervention group were significantly lower than those in the control group (SMD=-0.82, 95% CI=-1.04 ∼ -0.60, Pintervention and control groups (SMD=0.09, 95% CI=-0.07 ∼ 0.25, P=0.224). Subgroup analysis by ethnicity indicated that there were significant differences in RPFS and FACIT-F scores between the intervention and control groups among Asian populations (RPFS: SMD=-1.08, 95% CI=-1.35 ∼ -0.82, P0.05). The current meta-analysis indicates that aerobic exercise may improve cancer-related fatigue in breast cancer patients receiving chemotherapy, especially among Asian populations.

  16. Exercise Interventions to Reduce Cancer-Related Fatigue and Improve Health-Related Quality of Life in Cancer Patients.

    Science.gov (United States)

    Scott, Kelly; Posmontier, Bobbie

    Cancer-related fatigue (CRF) is the most common and debilitating side effect of patients receiving treatment of cancer. It is reported that 60% to 100% of patients will develop CRF as a result of the treatment or the cancer itself. The effects last for years posttreatment and lower overall quality of life. The purpose of this integrative review was to determine whether exercise interventions could reduce CRF and improve overall health-related quality of life (HRQOL) among selected cancer patients. Clinical Key, ProQuest Nursing and Allied Health Source, Cochrane Library, Mosby's Nursing Consult, and MEDLINE (Ovid) were the databases searched. Key terms searched were fatigue, exercise, cancer fatigue, holistic, spiritual, quality of life, and prevention. Findings from most studies suggest that exercise can decrease the effects of CRF among cancer patients, leading to an overall improved HRQOL. No negative results on the effects of exercise on CRF were reported. Nurses can be instrumental in developing holistic multidisciplinary exercise programs to assist in the management of CRF and improve HRQOL among cancer patients during and after cancer treatment. Recommendations for future research include the need for larger study sample sizes, a universal definition of fatigue, determination of the best exercise regimens, more consistent fatigue measures to facilitate better comparison across studies, and specifically assess patient improvements in overall mental and spiritual well-being within a holistic framework.

  17. Cancer-Related Fatigue and Rehabilitation : A Randomized Controlled Multicenter Trial Comparing Physical Training Combined With Cognitive-Behavioral Therapy With Physical Training Only and With No Intervention

    NARCIS (Netherlands)

    van Weert, E.; May, A.M.; Korstjens, I.; Post, W.J.; van der Schans, C.P.; van den Borne, B.; Mesters, I.; Ros, W.J.G.; Hoekstra-Weebers, J.E.H.M.

    2010-01-01

    Background. Research suggests that cancer rehabilitation reduces fatigue in survivors of cancer. To date, it is unclear what type of rehabilitation is most beneficial. Objective. This randomized controlled trial compared the effect on cancer-related fatigue of physical training combined with cogniti

  18. Cancer-Related Fatigue and Rehabilitation : A Randomized Controlled Multicenter Trial Comparing Physical Training Combined With Cognitive-Behavioral Therapy With Physical Training Only and With No Intervention

    NARCIS (Netherlands)

    van Weert, E.; May, A.M.; Korstjens, I.; Post, W.J.; van der Schans, C.P.; van den Borne, B.; Mesters, I.; Ros, W.J.G.; Hoekstra-Weebers, J.E.H.M.

    2010-01-01

    Background. Research suggests that cancer rehabilitation reduces fatigue in survivors of cancer. To date, it is unclear what type of rehabilitation is most beneficial. Objective. This randomized controlled trial compared the effect on cancer-related fatigue of physical training combined with

  19. Putting evidence into practice: an update of evidence-based interventions for cancer-related fatigue during and following treatment.

    Science.gov (United States)

    Mitchell, Sandra A; Hoffman, Amy J; Clark, Jane C; DeGennaro, Regina M; Poirier, Patricia; Robinson, Carolene B; Weisbrod, Breanna L

    2014-01-01

    Cancer-related fatigue (CRF) has deleterious effects on physical, social, cognitive, and vocational functioning, and causes emotional and spiritual distress for patients and their families; however, it remains under-recognized and undertreated. This article critically reviews and integrates the available empirical evidence supporting the efficacy of pharmacologic and nonpharmacologic treatment approaches to CRF, highlighting new evidence since 2007 and 2009 Putting Evidence Into Practice publications. Interventions that are recommended for practice or likely to be effective in improving fatigue outcomes include exercise; screening for treatable risk factors; management of concurrent symptoms; yoga; structured rehabilitation; Wisconsin ginseng; cognitive-behavioral therapies for insomnia, pain, and depression; mindfulness-based stress reduction; and psychoeducational interventions such as anticipatory guidance, psychosocial support, and energy conservation and activity management. This information can be applied to improve the management of CRF, inform health policy and program development, shape the design of clinical trials of new therapies for CRF, and drive basic and translational research.

  20. An examination of cancer-related fatigue through proposed diagnostic criteria in a sample of cancer patients in Taiwan

    Directory of Open Access Journals (Sweden)

    Su Wei-Ju

    2011-09-01

    Full Text Available Abstract Background Fatigue among cancer patients has often been reported in the literature; however, great variations have been documented, ranging from 15% to 90%, probably due to the lack of a widely accepted definition and established diagnostic criteria for cancer-related fatigue. The objective of this study was to evaluate the proposed International Statistical Classification of Diseases and Related Health Problems (10th revision (ICD-10 criteria in a sample of cancer patients from a medical center and a regional teaching hospital in northern Taiwan. More accurate prevalence estimates of CRF may result in improved diagnoses and management of one of the most common symptoms associated with cancer and its treatment. Methods Since self-reporting from patients is the most effective and efficient method to measure fatigue, the ICD-10 criteria for fatigue were used. The ICD-10 criteria questionnaire was translated into Chinese and was approved by experts. Patients were recruited from outpatient palliative and oncology clinics and from palliative and oncology inpatient units. Results Of the 265 cancer patients that were interviewed between 21 October 2008 and 28 October 2009, 228 (86% reported having at least 2 weeks of fatigue in the past month, and further evaluation with the ICD-10 criteria showed that 132 (49.8% had cancer-related fatigue. Internal consistency was very good, which was indicated by a Cronbach alpha of 0.843. Conclusion The prevalence of diagnosable CRF in the patients in this sample, of whom most were under palliative treatment, was 49.8%, which was probably somewhat lower than in some of the previous reports that have used less-strict criteria. In addition, among the various criteria of the proposed diagnostic criteria, the most frequently reported symptoms in our sample populations were regarding sleep disturbance and physical factors. Although they will require further replication in other samples, these formal diagnostic

  1. Effects of physical exercise during adjuvant breast cancer treatment on physical and psychosocial dimensions of cancer-related fatigue: A meta-analysis.

    Science.gov (United States)

    van Vulpen, Jonna K; Peeters, Petra H M; Velthuis, Miranda J; van der Wall, Elsken; May, Anne M

    2016-03-01

    Cancer-related fatigue has a multidimensional nature and complaints typically increase during adjuvant treatment for breast cancer. Physical exercise might prevent or reduce cancer-related fatigue. So far, no meta-analysis has investigated the effects of physical exercise on different dimensions of fatigue. The aim of the present meta-analysis was to investigate the effects of physical exercise during adjuvant breast cancer treatment on physical and psychosocial dimensions of fatigue. We performed a systematic literature search in PubMed, Embase and the Cochrane Library in June 2015. Randomised controlled trials reporting the effects of physical exercise during adjuvant breast cancer treatment on different dimensions of fatigue were included. Pooled effects of 6 exercise programmes (including 784 patients) showed significant beneficial exercise effects on general fatigue (ES: -0.22, 95% CI -0.38; -0.05) and physical fatigue (ES: -0.35, 95% CI -0.49; -0.21). Effects on fatigue subscales 'reduced activity' (ES: -0.22, 95% CI -0.38; -0.05) and 'reduced motivation' (ES: -0.18, 95% CI -0.35; -0.01) were also in favour of physical exercise. No effects were found on cognitive and affective fatigue. Including only the supervised exercise programmes (n=4 studies), slightly larger pooled effect estimates were found on general fatigue (ES: -0.25, 95% CI -0.47; -0.04) and physical fatigue (-0.39, 95% CI -0.56; -0.23). In conclusion, physical exercise during adjuvant breast cancer treatment has beneficial effects on general fatigue, physical fatigue, 'reduced activity' and 'reduced motivation', but did not show effects on cognitive and affective fatigue. Largest effect sizes are found for physical fatigue, suggesting that this is the fatigue dimension most sensitive to physical exercise.

  2. Effects of infrared laser moxibustion on cancer-related fatigue: A randomized, double-blind, placebo-controlled trial.

    Science.gov (United States)

    Mao, Huijuan; Mao, Jun J; Guo, Menghu; Cheng, Ke; Wei, Jianzi; Shen, Xubo; Shen, Xueyong

    2016-12-01

    Fatigue is the most common symptom negatively affecting the quality of life of patients with cancer. The objective of the current study was to evaluate the preliminary efficacy and safety of 10.6-μm infrared laser moxibustion for cancer-related fatigue (CRF). The authors conducted a randomized, placebo-controlled trial among 78 patients with cancer who were diagnosed with CRF. The group treated with infrared laser moxibustion received 10.6 μm of infrared laser moxibustion on the ST36 (bilateral), CV4, and CV6 acupoints. Each participant received a 20-minute treatment session 3 times per week for 4 weeks. The sham group received the same treatment duration on the same acupoints, but without infrared laser output. The outcome was change in fatigue as measured by the Chinese version of the Brief Fatigue Inventory between groups at week 4 with additional evaluation at week 8 for durability of treatment effects. A mixed effects model was used to evaluate the difference in treatment effect over time. Among those randomized, 61 patients (78%) completed the entire study. At the end of the intervention, the individuals in the group treated with the laser were found to have significantly less fatigue than those in the sham group (3.01 vs 4.40; P = .002). The improvement in fatigue persisted to week 8, favoring the group treated with laser moxibustion (3.03 vs 4.26; P = .006). Laser moxibustion was safe, with 3 cases of mild local erythema that resolved without medical intervention reported. Infrared laser moxibustion appeared to be safe and efficacious for improving CRF in a Chinese patient population. Larger studies in more racial/ethnically diverse populations are needed to confirm the benefit of this technique for fatigue in patients with cancer. Cancer 2016;122:3667-72. © 2016 The Authors. Cancer published by Wiley Periodicals, Inc. on behalf of American Cancer Society. This is an open access article under the terms of the Creative Commons Attribution

  3. Acupressure for persistent cancer-related fatigue in breast cancer survivors (AcuCrft: a study protocol for a randomized controlled trial

    Directory of Open Access Journals (Sweden)

    Zick Suzanna

    2012-08-01

    Full Text Available Abstract Background Despite high levels of clinically significant persistent cancer related fatigue in breast cancer survivors few treatments are currently available and most pose a significant burden on the part of the woman. Acupressure, a component of Traditional Chinese Medicine, has been shown to decrease fatigue levels by as much as 70% in cancer survivors while being inexpensive, non-toxic and an easy to use intervention. The primary aim of this study was to determine the efficacy of two types of self-administered acupressure (relaxation acupressure and stimulating acupressure, compared to standard of care on fatigue severity. Secondary aims were to evaluate the efficacy of two types of acupressure on sleep and kinetic parameters required for implementation of acupressure in a clinical setting; The purpose of this paper is to share the methodology used including challenges and insights. Methods/design This study is a three group, randomized clinical trial. 375 breast cancer survivors at least 12 months after completion of cancer treatments, with moderate to severe persistent fatigue, are being randomized to one of 3 groups: self-administered relaxation acupressure; self-administered stimulating acupressure; or standard of care. Participants are assessed at baseline, 3 weeks, and 6 weeks followed by a 4-week follow-up period. The primary aim is to examine the effect of 6-weeks of relaxation acupressure compared to stimulatory acupressure or standard of care on fatigue as assessed by: weekly self-report using the Brief Fatigue Inventory; objective daytime physical activity on actigraph; or fatigue patterns assessed 4-times daily using a visual analog scale. Secondary endpoints include depression, anxiety, self-efficacy, and sleep quality. Discussion This study has the potential to develop a low-cost, self-care intervention for the most troubling of late-term effects in breast cancer populations, fatigue. The methods used may lend

  4. Development and evaluation of a cancer-related fatigue patient education program: protocol of a randomized controlled trial

    Directory of Open Access Journals (Sweden)

    Görres Stefan

    2008-07-01

    Full Text Available Abstract Background Cancer-related fatigue (CRF and its impact on patients' quality of life has been an increasing subject of research. However, in Germany there is a lack of evidence-based interventions consistent with the multidimensional character of fatigue. The objective of this study is to develop and evaluate a self-management program for disease-free cancer patients to cope with CRF. Methods Based on evidence extracted from a literature review, a curriculum for the self-management program was elaborated. The curriculum was reviewed and validated by an interdisciplinary expert group and the training-modules will be pretested with a small number of participants and discussed in terms of feasibility and acceptance. To determine the efficacy of the program a randomised controlled trial will be carried out: 300 patients will be recruited from oncological practices in Bremen, Germany, and will be allocated to intervention or control group. The intervention group participates in the program, whereas the control group receives standard care and the opportunity to take part in the program after the end of the follow-up (waiting control group. Primary outcome measure is the level of fatigue, secondary outcome measures are quality of life, depression, anxiety, self-efficacy and physical activity. Data will be collected before randomisation, after intervention, and after a follow-up of 6 months. Discussion Because there are no comparable self-management programs for cancer survivors with fatigue, the development of the curriculum has been complex; therefore, the critical appraisal by the experts was an important step to validate the program and their contributions have been integrated into the curriculum. The experts appreciated the program as filling a gap in outpatient cancer care. If the results of the evaluation prove to be satisfactory, the outpatient care of cancer patients can be broadened and supplemented. Trial Registration Clinical

  5. Inflammation-induced activation of the indoleamine 2,3-dioxygenase pathway: Relevance to cancer-related fatigue.

    Science.gov (United States)

    Kim, Sangmi; Miller, Brian J; Stefanek, Michael E; Miller, Andrew H

    2015-07-01

    Cancer-related fatigue (CRF) is a common complication of cancer and its treatment that can significantly impair quality of life. Although the specific mechanisms remain poorly understood, inflammation is now considered to be a distinct component of CRF in addition to effects of depression, anxiety, insomnia, and other factors. One key biological pathway that may link inflammation and CRF is indoleamine 2,3-dioxygenase (IDO). Induced by inflammatory stimuli, IDO catabolizes tryptophan to kynurenine (KYN), which is subsequently converted into neuroactive metabolites. Here we summarize current knowledge concerning the relevance of the IDO pathway to CRF, including activation of the IDO pathway in cancer patients and, as a consequence, accumulation of neurotoxic KYN metabolites and depletion of serotonin in the brain. Because IDO inhibitors are already being evaluated as therapeutic agents in cancer, the elucidation of the relationship between IDO activation and CRF in cancer patients may lead to novel diagnostic and clinical approaches to managing CRF and its debilitating consequences.

  6. "Cancer-Related Fatigue: A Systematic and Meta-Analytic Review of Nonpharmacological Therapies for Cancer Patients:" Correction to Kangas, Bovbjerg, and Montgomery (2008)

    Science.gov (United States)

    Kangas, Maria; Bovbjerg, Dana H.; Montgomery, Guy H.

    2009-01-01

    Reports an error in "Cancer-related fatigue: A systematic and meta-analytic review of non-pharmacological therapies for cancer patients" by Maria Kangas, Dana H. Bovbjerg and Guy H. Montgomery (Psychological Bulletin, 2008[Sep], Vol 134[5], 700-741). The URL to the Supplemental Materials for the article is listed incorrectly in two places in the…

  7. Fadiga relacionada ao câncer: uma revisão Cancer-related fatigue: a review

    Directory of Open Access Journals (Sweden)

    Maira Paschoin de Oliveira Campos

    2011-04-01

    este sintoma tão importante e de grande impacto na qualidade de vida de pacientes com câncer.Cancer-related fatigue is the most prevalent cancer symptom, reported in 50%-90% of patients and severely impacts quality of life and functional capacity. The condition remains underreported and often goes untreated. Guidelines suggest screening for fatigue at the initial visit, when the diagnosis of advanced disease is made, and at each chemotherapy session, as well as the identification of treatable contributing factors such as anemia, hypothyroidism, depression and sleep disorders. Brief assessment tools such as the Brief Fatigue Inventory or the Visual Analog Scale may be appropriate in the initial scoring of fatigue severity, but the initial approach to treatment usually requires a more comprehensive assessment, education, and the determination of an individualized treatment plan. Patients with moderate or severe fatigue may benefit from both pharmacological and non-pharmacological interventions, whereas mild fatigue that does not interfere with quality of life can be treated with non-pharmacological measures alone. Non-pharmacological measures that have shown to be promising include cognitive-behavioral interventions such as energy conservation and activity management (ECAM, exercise and perhaps sleep therapy. Many other modalities may be beneficial and can be used on an individual basis, but there is insufficient evidence to promote any single treatment. Pharmacological therapies that have shown to be promising include the psycho-stimulants methylphenidate and dexmethylphenidate, modafinil (in severely fatigued patients only, and erythropoietin-stimulating agents in patients with chemotherapy-associated anemia and hemoglobin levels < 10 g/dL. Recently, our group reported impressive results with the use of the dry extract of Guarana (Paullinia cupana, with no significant side effects and at low cost, for the treatment of physical and mental cancer-related fatigue.

  8. Teenage and Young Adult Cancer-Related Fatigue Is Prevalent, Distressing, and Neglected: It Is Time to Intervene. A Systematic Literature Review and Narrative Synthesis

    Science.gov (United States)

    Booth, Sara; Grove, Sarah; Hatcher, Helen; Kuhn, Isla; Barclay, Stephen

    2015-01-01

    Purpose: Cancer-related fatigue in adults has been the subject of considerable recent research, confirming its importance as a common and debilitating symptom, and establishing a number of evidence-based interventions. There has, however, been limited focus on the fatigue suffered by teenagers and young adults with cancer, a group recognized as having unique experiences and developmental needs. We have undertaken a systematic review of the literature to provide a comprehensive overview of studies evaluating fatigue in this younger patient group in order to guide clinical practice and future research. Method: We searched MEDLINE, EMBASE, PsycINFO, and CINAHL databases for literature containing data relating to any aspect of fatigue in patients aged 13–24 at cancer diagnosis or treatment. Results: Sixty articles were identified, of which five described interventional clinical trials. Cancer-related fatigue was consistently one of the most prevalent, severe, and distressing symptoms, and it persisted long-term in survivors. It was associated with a number of factors, including poor sleep, depression, and chemotherapy. There was little evidence for the effectiveness of any intervention, although exercise appears to be the most promising. Importantly, fatigue was itself a significant barrier to physical and social activities. Conclusion: Cancer-related fatigue is a major and disabling problem in young cancer patients. Effective management strategies are needed to avoid compounding the dependence and social isolation of this vulnerable patient group. Future research should focus on providing evidence for the effectiveness of interventions, of which activity promotion and management of concurrent symptoms are the most promising. PMID:25852970

  9. Effects of Energy Conservation Strategies on Cancer Related Fatigue and Health Promotion Lifestyle in Breast CancerSurvivors: a Randomized Control Trial

    Science.gov (United States)

    Sadeghi, Elham; Gozali, Nahid; Moghaddam Tabrizi, Fatemeh

    2016-10-01

    Purpose: Cancer-related fatigue is frequently experienced by patients during and after therapy. The present study was conducted to assess the impact of energy conservation strategies and health promotion in breast cancer survivors. Methods: A randomized controlled trial was carried out to compare the intervention effect (n=69.0) with controls (n=66.0) based on routine oncology ward care. The intervention was five weekly sessions for groups of 6-8 breast cancer survivors. Data on fatigue and health promotion lifestyle were obtained before and after completion the intervention and then 8 weeks later for analysis of variance (ANOVA) with repeated measures. Results: Our findings showed cancer-related fatigue to be reduced in the intervention group from pre- to post-intervention, and this persisted over the 8-weeks follow-up period (F = 69.8, p<0.001). All subscales of the cancer fatigue scale demonstrated statistically significant effects with partial eta-squared values ranging from 0.15 (the smallest effect in cognitive fatigue) to 0.21 (the largest for affective fatigue). Changes in the health promotion life style indicated a significant promotion from pre- to post-intervention, and this again continued after 8-weeks follow-up (F = 41.6, p < 0.001). All six domains of a health promoting life style featured significantly elevated values, the largest effect being seen in the interpersonal relations subscale (F=57.7, partial η2=0.21, p<0.001) followed by physical activity (F=51.9, partial η2=0.18, p<0.001). Conclusions: The program was effective in decreasing cancer related fatigue and promoting a healthy lifestyle.

  10. The effectiveness of a deep water aquatic exercise program in cancer-related fatigue in breast cancer survivors: a randomized controlled trial.

    Science.gov (United States)

    Cantarero-Villanueva, Irene; Fernández-Lao, Carolina; Cuesta-Vargas, Antonio I; Del Moral-Avila, Rosario; Fernández-de-Las-Peñas, César; Arroyo-Morales, Manuel

    2013-02-01

    To investigate the effectiveness of an 8-week aquatic program on cancer-related fatigue, as well as physical and psychological outcomes in breast cancer survivors. A randomized controlled trial. Outpatient clinic, urban, academic medical center, and a sport university swimming pool. Breast cancer survivors (N=68) were randomly assigned to either an experimental (aquatic exercise group in deep water pool) group or a control (usual care) group. The intervention group attended aquatic exercise sessions 3 times per week for 8 weeks in a heated deep swimming pool. Sessions lasted 60 minutes in duration: 10 minutes of warm-up, 40 minutes of aerobic and endurance exercises, and 10 minutes of cool-down exercises. Patients allocated to the usual care group followed the oncologist's recommendations in relation to a healthy lifestyle. Values for fatigue (Piper Fatigue Scale), mood state (Profile of Mood States), and abdominal (trunk curl static endurance test) and leg (multiple sit-to-stand test) strength were collected at baseline, after the last treatment session, and at a 6-month follow-up. Immediately after discharge, the aquatic exercise group showed a large effect size in total fatigue score (d=.87; 95% confidence interval, .48-1.26), trunk curl endurance (d=.92; 95% confidence interval, 1.97-3.83), and leg strength (d=1.10; .55-2.76), but negligible effects in vigor, confusion, and disturbance of mood (dexercise group maintained large to small effect sizes in fatigue scores, multiple sit-to-stand test, and trunk curl static endurance (.25>d>.90) and negligible effects for the fatigue-severity dimension and different scales of the Profile of Mood States (dexercise program conducted in deep water was effective for improving cancer-related fatigue and strength in breast cancer survivors. Copyright © 2013 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

  11. Factors associated with cancer-related fatigue in breast cancer patients undergoing endocrine therapy in an urban setting: a cross-sectional study

    Directory of Open Access Journals (Sweden)

    Huang Xu

    2010-08-01

    Full Text Available Abstract Background Fatigue is prevalent in breast cancer survivors and has profound effects on daily life. The interference of fatigue with endocrine therapy may be difficult to separate. This study investigates the prevalence and severity of fatigue and identifies the demographic, clinical, and lifestyle factors associated with cancer-related fatigue (CRF in breast cancer patients undergoing endocrine therapy in an urban area. Methods Women with stage I-IIIA breast cancer were recruited and asked to participate (n = 371 in the study. The 315 women who responded to the questionnaire (84.9%, 54 (17.1% had completed endocrine therapy and 261 (82.9% were still undergoing endocrine therapy. The patients had been diagnosed at an average of 31 months prior to recruitment (range, 7 to 60 months; the average age was 48 (range, 33 to 72 years. The 11-point scale and Visual Analog Scale (VAS were employed to quantify the level of fatigue experienced by the patients. Logistic regression analyses and a trend test method were performed to evaluate factors associated with CRF. Results Among the 315 patients, 189 (60% had experienced or were experiencing CRF during endocrine therapy. Logistic regression analysis was performed to identify factors associated with CRF, including BMI (body mass index, clinical stage, menopausal status, duration of endocrine therapy, physical activity, and diet. Factors unrelated to CRF were age, marital status, treatment, endocrine therapy drugs, alcohol intake, and smoking. The trend test method revealed an association between physical activity and dietary level and the intensity of CRF. Conclusions The present findings suggest that fatigue is an important problem in the majority of breast cancer patients during endocrine therapy. We found that BMI, clinical stage, menopausal status, duration of endocrine therapy, physical activity, and diet are associated with fatigue. Future research should focus on the impact factors of CRF

  12. Cancer related fatigue in patients with breast cancer after chemotherapy and coping style%乳腺癌术后化疗患者癌因性疲乏与应对方式的研究

    Institute of Scientific and Technical Information of China (English)

    姜萍岚; 王曙红; 蒋冬梅; 虞玲丽

    2011-01-01

    目的:探讨乳腺癌术后化疗患者癌因性疲乏水平与应对方式的关系.方法:采用癌症疲乏量表和Jalowiec应对量表对396例乳腺癌术后化疗患者进行问卷调查,并分析其相关性.结果:乳腺癌术后化疗患者总疲乏发生率为96.97%,以中度疲乏最为明显;各维度疲乏发生率由高到低依次为躯体疲乏、情感疲乏、认知疲乏;乳腺癌术后化疗患者应对方式得分由高到低依次为乐观、勇敢面对、寻求支持、自我依赖、情感宣泄、逃避、听天由命、保守,其中应用最多的是乐观应对方式,应用最少的应对方式是情感宣泄;情感宣泄应对方式与癌因性疲乏各维度均呈正相关(P<0.01);乐观、勇敢面对、寻求支持、自我依赖、保守应对方式与情感疲乏呈负相关(P<0.05);乐观、寻求支持应对方式与躯体疲乏呈负相关(P<0.05);逃避、听天由命应对方式与总疲乏、躯体疲乏、认知疲乏维度均呈正相关(P<0.05).结论:乳腺癌患者普遍存在癌因性疲乏,应引导患者更多地采用积极有效的应对方式,避免采用消极的应对方式,以增强患者的心理适应能力,减轻癌因性疲乏,提高患者生活质量.%Objective To study the relevance between cancer related fatigue and coping styles in breast cancer patients after chemotherapy. Methods A survey was conducted in 396 patients with breast cancer after chemotherapy on cancer related fatigue scale and Jalowiec coping scale, and the relation was analyzed. Results The rate of overall fatigue in breast cancer patients was 96.97%, mostly moderate fatigue. The rate of fatigue dimensions from high to low was physical fatigue, feeling fatigue and cognitive fatigue, respectively. The score of coping styles in patients with breast cancer after chemotherapy from high to low was optimistic coping, facing bravely, support seeking, self-reliance, emotional catharsis, avoidance, fatalism, and conservation. The most

  13. Effects of Supervised Multimodal Exercise Interventions on Cancer-Related Fatigue: Systematic Review and Meta-Analysis of Randomized Controlled Trials

    Directory of Open Access Journals (Sweden)

    José Francisco Meneses-Echávez

    2015-01-01

    Full Text Available Objective. Cancer-related fatigue (CRF is the most common and devastating problem in cancer patients even after successful treatment. This study aimed to determine the effects of supervised multimodal exercise interventions on cancer-related fatigue through a systematic review and meta-analysis. Design. A systematic review was conducted to determine the effectiveness of multimodal exercise interventions on CRF. Databases of PubMed, CENTRAL, EMBASE, and OVID were searched between January and March 2014 to retrieve randomized controlled trials. Risk of bias was evaluated using the PEDro scale. Results. Nine studies n=772 were included in both systematic review and meta-analysis. Multimodal interventions including aerobic exercise, resistance training, and stretching improved CRF symptoms (SMD=-0.23; 95% CI: −0.37 to −0.09; P=0.001. These effects were also significant in patients undergoing chemotherapy P<0.0001. Nonsignificant differences were found for resistance training interventions P=0.30. Slight evidence of publication bias was observed P=0.04. The studies had a low risk of bias (PEDro scale mean score of 6.4 (standard deviation (SD ± 1.0. Conclusion. Supervised multimodal exercise interventions including aerobic, resistance, and stretching exercises are effective in controlling CRF. These findings suggest that these exercise protocols should be included as a crucial part of the rehabilitation programs for cancer survivors and patients during anticancer treatments.

  14. Sympathetic and Parasympathetic Activity in Cancer-Related Fatigue: More Evidence for a Physiological Substrate in Cancer Survivors

    OpenAIRE

    2011-01-01

    Fatigue is a notable clinical problem in cancer survivors, and understanding its pathophysiology is important. This study evaluated relationships between fatigue and both sympathetic and parasympathetic nervous system activity in breast cancer survivors. Norepinephrine and heart rate variability (HRV) were evaluated at rest, as well as during and after a standardized laboratory speech and mental arithmetic stressor. The participants, 109 women who had completed treatment for stage 0-IIIA brea...

  15. Web-based individual Mindfulness-Based Cognitive Therapy for cancer-related fatigue — A pilot study

    Directory of Open Access Journals (Sweden)

    Fieke Z. Bruggeman Everts

    2015-05-01

    Conclusion: These findings suggest that individual eMBCT may be effective in reducing fatigue in cancer survivors. A randomized controlled study with a large sample and longer follow up is needed to demonstrate the effectiveness of eMBCT for CRF.

  16. 瑜伽对乳腺癌患者癌因性疲乏干预效果的Meta分析%Effects of Yoga on cancer-related fatigue in breast cancer patients:Meta-analysis

    Institute of Scientific and Technical Information of China (English)

    张琪; 朴丽; 赵东梅; 武兴; 丛云凤

    2015-01-01

    Meta-analysis results revealed that Yoga played certain effects to release breast cancer related fatigue. Conclusions Whether Yoga, as a effective method to release breast cancer related fatigue, can be generally promoted in clinical required clinical high quality, large sampling and multicenter RCTs to support.

  17. Construction of the Chinese cancer-related fatigue assessment scale by using Delphi technique%运用Delphi法构建中国癌因性疲乏评估量表

    Institute of Scientific and Technical Information of China (English)

    李艳; 袁长蓉

    2009-01-01

    目的 应用Delphi法构建中国的癌因性疲乏评估工具.方法 选择咨询专家、形成专家咨询表,进行2轮专家咨询并分析咨询结果.结果 通过2轮咨询确立中国癌因性疲乏评估量表的结构和内容:躯体疲乏8个条目、精神疲乏5个条目、情绪状态7个条目.结论 Delphi法所确立的中国癌因性疲乏评估量表为准确地评估中国肿瘤患者的疲乏,提出针对性的护理干预措施贡献研究工具.%Objective To construct the Chinese cancer-related fatigue assessment tool by using Delphi technique.Methods A certain number of expels were chosen for consulting to form a consuiting scale.Two-round consultations were conducted and the results were analyzed.Results The Chinese cancer-related fatigue assessment scale was formed after 2-round consultation,including 3 dimensions and 20 items,which were:8 items for the physical fatigue,5 items for mental fatigue,7 items for emotional condition.Conclusions The Chinese cancer-related fatigue assessment scale formed by Delphi technique provides a research tool to evaluate fatigue of Chinese cancer patients accurately and presents targeted nursing interventions.

  18. The Corrosion Fatigue Properties of High Performance Concrete

    Institute of Scientific and Technical Information of China (English)

    CHEN Shuanfa; ZHENG Mulian; LIAO Weidong; WANG Binggang

    2005-01-01

    With the loading test equipment of corrosion fatigue specially designed, the corrosion fatigue characteristics of high performance concrete (HPC) withstanding the interaction of third point fatigue loading and Na2SO4 solution were investigated and analyzed. The experimental results indicate that water-binder ratio evidently influences the corrosion fatigue characteristics of HPC, and a moderate quantitative fine mineral admixture enhances the corrosion fatigue resistance of HPC. The effect is more significant when fly ash and silica fume are added.

  19. Influence Factors of Cancer-related Fatigue of Patients with Cervical Cancer%宫颈癌患者癌因性疲乏的影响因素分析

    Institute of Scientific and Technical Information of China (English)

    郑艳; 王喜华; 李萍

    2014-01-01

    目的:调查宫颈癌放疗患者家庭功能和癌因性疲乏的现况,分析癌因性疲乏的影响因素。方法应用一般情况调查表、疾病相关因素调查表、家庭功能评定量表和疲劳评定量表,采用配额抽样法对新疆乌鲁木齐市3所三级甲等医院放疗科的124例宫颈癌患者进行调查。结果85例患者存在中、重度家庭功能障碍,72例患者存在中、重度癌因性疲乏,患者的家庭功能总分与癌因性疲乏总分呈正相关(r=0.759,P<0.05)。多元逐步回归分析显示,家庭功能、年龄、医疗付费方式、血清钾水平、工作情况、健康教育、放疗不良反应和白细胞水平是宫颈癌放疗患者癌因性疲乏的主要影响因素(P<0.05);结论宫颈癌放疗患者家庭功能越低,患者的癌因性疲乏程度越重。提高家庭成员对患者的关爱,对于高龄、自费、文化程度偏低及治疗期间继续工作的患者和合并代谢紊乱并伴有放疗不良反应的患者,早期应考虑对其癌因性疲乏实施干预,帮助她们预防和减轻疲乏。%Objective To survey the current status of family functioning and cancer-related fatigue of patients with cervical cancer and to analyze the influence factors of cancer-related fatigue. Methods With general questionnaires, disease-related factors questionnaires, Family Assessment Device and Fatigue Assessment Instrument, we employed a quota sampling method to investigate 124 cervical cancer patients in radiotherapy departments of Class Ⅲ GradeⅠ hospitals in Urumqi, Xinjiang. Results Medium and heavy family dysfunction was found among 85 patients and medium and heavy cancer-related fatigue among 75 patients. Pearson correlation analysis showed there was a positive correlation between patients ’ family function and cancer related fatigue (r=0.759, P<0.01). Multiple regression analysis showed that family functioning, age, medical payment method, serum potassium

  20. High temperature fatigue behaviour of intermetallics

    Indian Academy of Sciences (India)

    K Bhanu Sankara Rao

    2003-06-01

    There would be considerable benefits in developing new structural materials where high use temperatures and strength coupled with low density are minimum capabilities. Nickel and titanium aluminides exhibit considerable potential for near-term application in various branches of modern industry due to the number of property advantages they possess including low density, high melting temperature, high thermal conductivity, and excellent environmental resistance, and their amenability for significant improvment in creep and fatigue resistance through alloying. Reliability of intermetallics when used as engineering materials has not yet been fully established. Ductility and fracture toughness at room and intermediate temperatures continue to be lower than the desired values for production implementation. In this paper, progress made towards improving strain-controlled fatigue resistance of nickel and titanium aluminides is outlined. The effects of manufacturing processes and micro alloying on low cycle fatigue behaviour of NiAl are addressed. The effects of microstructure, temperature of testing, section thickness, brittle to ductile transition temperature, mean stress and environment on fatigue behaviour of same -TiAl alloys are discussed.

  1. Correlation between Cancer-related Fatigue and Personality in Patients of Laryngeal Canc er with Chemotherapy%喉癌化疗患者癌因性疲乏与人格的相关性

    Institute of Scientific and Technical Information of China (English)

    李雪; 左迪; 张欢; 葛丽宏

    2015-01-01

    Objective:To probe the relationship between the degree of cancer -related fatigue ( CRF ) and personality in patients of laryngeal cancer with chemotherapy .Methods:Cross-sectional study and the general Questionnaire ,Cancer Fatigue Scare ( CRF) and Eysenck Personality Questionnaire( EPQ) were used for survey laryngeal cancer inpatients ,and the correlation between them was analyzed .Rseults:①The mean score of CRF was(34.44 ±7.01),and 96 patients had suffered moderate fatigue;②The scores of neuroticism and psychoticism in these patients were higher than the national norm (t=7.586,3.772;P<0.01),but the score of introversion&extraversion and EPQ -L had no obvious difference with the na-tional norm;③There were significantly positive correlations among neuroticism and cancer -related fa-tigue,physical fatigue,mental fatigue,cognitive fatigue(r=0.529,0.291,0.555,0.357;P<0.01);④There was a significantly positive correlation between psychoticism and mental fatigue ( r=0.203,P<0.05);⑤There were negative correlations among introversion &extraversion and cancer -related fatigue as well as mental fatigue( r=-0.353,-0.500;P<0.01).Conclus ion:Cancer -related fatigue is wide-spread in patients of laryngeal cancer with chemotherapy ,which is in the moderate level;Cancer-related fatigue is influenced by the personality factors .%目的:探讨喉癌化疗患者癌因性疲乏与人格之间的关系。方法:采用横断面调查方法,运用一般资料问卷、癌因性疲乏量表、艾森克人格问卷简式量表对喉癌化疗患者进行调查,分析癌因性疲乏状况及其与人格之间的关系。结果:①在96例被调查者中,喉癌化疗患者癌因性疲乏呈中等水平,得分为(34.44±7.01)分;②喉癌化疗患者的神经质、精神质评分显著高于全国常模(t=7.586,3.772;P<0.01),而内外向及掩饰性评分与全国常模间无显著性差异( t=1.675,0.085;P>0.05);③

  2. Research progress on exercise intervention for cancer- related fatigue in breast cancer patients%乳腺癌病人癌因性疲乏运动干预的研究进展

    Institute of Scientific and Technical Information of China (English)

    陈亚梅; 王维利; 周利华

    2012-01-01

    随着生物-心理-社会医学模式的建立以及乳腺癌病人生存期的延长,癌因性疲乏的干预越来越受到肿瘤护理人员的重视,而运动干预是缓解乳腺癌病人癌因性疲乏的有效手段,本研究针对乳腺癌病人癌因性疲乏的运动干预形式、强度、时间及频率等进行综述,为肿瘤护理人员实施运动干预提供参考.%With the establishment of biological - psychological - social medical model and the free survival extend of the breast cancer patients , the interventions for cancer - related fatigue have got the more and more attention of the tumor nursing staff. However,exercise intervention is the effective means to alleviate the cancer - related fatigue of breast cancer patients. This research reviewed the form,intensity,time and frequency of exercise intervention for cancer - related fatigue of breast cancer patients, and provided the references for tumor nursing staff carrying out exercise intervention for them.

  3. High cycle fatigue characteristics of 2124-T851 aluminum alloy

    Institute of Scientific and Technical Information of China (English)

    LI Xue; YIN Zhimin; NIE Bo; ZHONG Li; PAN Qinglin; JIANG Feng

    2007-01-01

    The fatigue crack growth rate, fracture toughness and fatigue S-N curve of 2124-T851 aluminum alloy at high cycle fatigue condition were measured and fatigue fracture process and fractography were studied using optical microscopy (OM), X-ray diffraction (XRD) technique, trans-mission electron microscopy (TEM) and scanning electron microscopy (SEM). The results show that at room tempera-ture and R = 0.1 conditions, the characteristics of fatigue fracture could be observed. Under those conditions, the fatigue strength and the fracture toughness of a 2124-T851 thick plate is 243 MPa and 29.64 MPa·m1/2,respectively.At high cycle fatigue condition, the higher the stress amplitude,the wider the space between fatigue striations, the faster the rate of fatigue crack developing and going into the intermittent fracture area, and the greater the ratio between the intermittent fracture area and the whole fracture area.

  4. 肺癌化疗患者癌因性疲乏状况调查分析%Investigation and analysis on the status of cancer-related fatigue in lung cancer patients treated by chemotherapy

    Institute of Scientific and Technical Information of China (English)

    张景屹; 杜红娣

    2012-01-01

    Objective To discuss the influencing factors and the status of cancer-related fatigue in lung cancer patients treated with chemotherapy. Methods 101 patients with lung cancer were selected in Beijing union medical college hospital in January 2008. The degree related to fatigue and related factors measurement were measured by fatigue self-assessment scale of Piper. Results Cancer-related fatigue of lung cancer patients were moderate degree, there was significant difference between sleep and fatigue degree (P < 0.01). There was significant difference between mood and fatigue degree (P < 0.01); The influence of age, gender, education degree of marital status and treatment were not distinct. Conclusion Patients will be prone to fatigue of moderate degree in they are receiving chemotherapy period, sleep and mood are main influence factors, the nurse should provide targeted nursing according to patients' sleep and mood, in order to improve the status of cancer-related fatigue in lung cancer patients.%目的 探讨肺癌化疗患者癌因性疲乏状况及影响因素.方法 便利抽样选取2008年1月在北京协和医院明确诊断为肺癌并接受治疗的患者101例,采用Piper疲劳自评量表进行癌因性疲乏程度及相关因素测量.结果 肺癌患者癌因性疲乏属于中度程度,不同睡眠情况患者疲乏程度差异有统计学意义(P < 0.01);不同情绪状态患者疲乏程度差异有统计学意义(P < 0.01);性别、年龄、婚姻状况、教育程度和治疗方案对癌因性疲乏程度影响不明显.结论 在患者接受化疗期间,化疗易发生中等程度的疲劳,睡眠、情绪状态是疲乏的主要影响因素,护理人员应针对患者的睡眠和情绪状况提供更有针对性的护理,以改善肺癌化疗患者的癌因性疲劳状况.

  5. 卵巢癌患者癌因性疲乏体验的质性研究%A qualitative study on cancer-related fatigue among ovarian cancer patients

    Institute of Scientific and Technical Information of China (English)

    高丹; 曹耀萍

    2012-01-01

    Objective To investigate the factors related to cancer-related fatigue(CRF) in ovarian cancer patients. Methods 16 ovarian cancer patients in the gynecological ward of a third grade and first level hospital were involved in the investigation by an in-depth interview. Giorgy data analysis was used to summarize main factors. Results The factors related to cancer-related fatigue included the influence from chemotherapic medication, economic factors, mental pressure, family support and care and environmental factors. The CRF clinical manifests of the ovarian cancer patients included body fatigue at different degrees, different mental fatigues as well as the consequences from the fatigues. Conclusions The CRF is a subjective and multi-dimensional pains for the ovarian cancer patients, which however gains little attention clinically. Therefore, we should take measures to intervene in CRF so as to provide individualized support and care to them.%目的 了解卵巢癌患者癌因性疲乏(cancer related fatigue,CRF)的感受及体验,为患者提供更加个性化的支持照护提供依据.方法 采用现象学研究方法对在某三甲医院妇科病房住院的16例卵巢癌患者进行深度访谈,并采用Giorgy资料分析方法进行分析、提炼主题.结果 卵巢癌患者CRF形成原因主要为化疗药物的影响、经济因素、精神压力、家庭支持和照顾、环境因素;卵巢癌患者CRF临床表现为不同程度的躯体疲乏、多种精神疲乏及由此产生多种疲乏后果.结论 癌因性疲乏是卵巢癌患者普遍存在主观的、多维度的痛苦体验,临床上未引起重视.医护人员应对癌因性疲乏进行有效地干预,为卵巢癌患者提供个性化的支持照护.

  6. A web-based intervention (RESTORE) to support self-management of cancer-related fatigue following primary cancer treatment: a multi-centre proof of concept randomised controlled trial

    OpenAIRE

    Foster, Claire; Grimmett, Chloe; May, Christine M.; Ewings, Sean; Myall, Michelle; Hulme, Claire; Smith, Peter W.; Powers, Cassandra; Calman, Lynn; Armes, Jo; Breckons, Matthew; Corner, Jessica; Fenlon, Deborah; Batehup, Lynn; Lennan, Elaine

    2015-01-01

    Purpose: Cancer-related fatigue (CRF) is a frequent and distressing symptom experienced after cancer treatment. RESTORE is the first web-based resource designed to enhance self-efficacy to manage CRF following curative-intent treatment. The aim of this study is to test the proof of concept and inform the design of an effectiveness trial.\\ud \\ud Methods: A multi-centre parallel-group two-armed (1:1) exploratory randomised controlled trial (RCT) with qualitative process evaluation was employed ...

  7. 结直肠癌病人癌因性疲乏的护理干预研究进展%Progress on nursing interventions of colorectal cancer patients with cancer-related fatigue

    Institute of Scientific and Technical Information of China (English)

    李雪; 李卡

    2012-01-01

    It summarized the nursing interventions of colorectal cancer patients with cancer - related fatigue (CRF), and reviewed from definition and pathogenesis of CRF.impact factors,assessment,treatment and nursing measures of colorectal cancer patients with CRF.%总结了结直肠癌病人癌因性疲乏(CRF)的护理干预措施,从CRF定义及发病机制,结直肠癌病人CRF的影响因素、评估、治疗及护理措施等方面进行了综述.

  8. Cancer-related fatigue and rehabilitation: A randomized controlled multicenter trial comparing physical training combined with cognitive-behavioral therapy with physical training only and with no intervention

    NARCIS (Netherlands)

    E. van Weert (Ellen); A.M. May (Anne); I. Korstjens (Irene); W.J. Post (Wendy); C.P. van der Schans (Cees); B. van den Borne (Bart); I. Mesters (Ilse); W.J.G. Ros (Wynand); J.E.H.M. Hoekstra-Weebers (Josette)

    2010-01-01

    textabstractBackground. Research suggests that cancer rehabilitation reduces fatigue in survivors of cancer. To date, it is unclear what type of rehabilitation is most beneficial. Objective. This randomized controlled trial compared the effect on cancerrelated fatigue of physical training combined

  9. Cancer-related fatigue and rehabilitation: A randomized controlled multicenter trial comparing physical training combined with cognitive-behavioral therapy with physical training only and with no intervention

    NARCIS (Netherlands)

    E. van Weert (Ellen); A.M. May (Anne); I. Korstjens (Irene); W.J. Post (Wendy); C.P. van der Schans (Cees); B. van den Borne (Bart); I. Mesters (Ilse); W.J.G. Ros (Wynand); J.E.H.M. Hoekstra-Weebers (Josette)

    2010-01-01

    textabstractBackground. Research suggests that cancer rehabilitation reduces fatigue in survivors of cancer. To date, it is unclear what type of rehabilitation is most beneficial. Objective. This randomized controlled trial compared the effect on cancerrelated fatigue of physical training combined w

  10. Effect of Orem self-care model on cancer related fatigue in patients with advanced carcinoma of the larynx%Orem自理模式对晚期声门癌患者癌因性疲乏的影响

    Institute of Scientific and Technical Information of China (English)

    钟时汝; 马玲国; 王木清

    2016-01-01

    目的:探讨Orem自理模式对晚期声门癌患者癌因性疲乏的影响。方法选取2013年2月至2016年2月入住我院的120例晚期声门癌患者,按随机数表法分为观察组与对照组,每组60例,对照组患者予以临床传统的常规护理措施进行护理,观察组患者则予以Orem自理模式进行护理,比较两组患者的癌因性简短疲乏评估量表(BFI)评分及癌因性疲乏发生率等情况。结果护理干预后,观察组患者的BFI评分为(4.05±1.34)分,明显少于对照组的(5.12±1.20)分,差异具有统计学意义(P<0.05);观察组患者癌因性疲乏总体发生率为66.67%,明显低于对照组的88.33%,差异具有统计学意义(P<0.05)。结论在晚期声门癌患者的治疗中实施Orem自理模式的综合护理干预,能显著降低患者癌因性疲乏程度,降低癌因性疲乏发生率,促进患者康复,提高患者生活生存质量,值得临床推广应用。%Objective To investigate the influence of Orem self-care model on cancer related fatigue in pa-tients with advanced carcinoma of the larynx. Methods A total of 120 cases of advanced glottic cancer patients admit-ted to our hospital from February 2013 to February 2016, were randomly divided into observation group and control group according to random number table, with 60 cases in each group. Patients in the control group received the tradi-tional clinical routine nursing , and patients in the observation group received Orem self-care model. Cancer related brief fatigue inventory (BFI) scores and cancer rate due to fatigue of two groups were observed and compared. Results After nursing intervention, BFI scores of the observation group (4.05 ± 1.34) were significantly lower than that of the control group (5.12 ± 1.20), P<0.05. The overall incidence of cancer related fatigue in observation group (66.67%) was signifi-cantly lower than that in the control group (88.33%), P<0.05. Conclusion The

  11. Fatigue Life of High-Strength Steel Offshore Tubular Joints

    DEFF Research Database (Denmark)

    Petersen, Rasmus Ingomar; Agerskov, Henning; Lopez Martinez, Luis

    1996-01-01

    In the present investigation, the fatigue life of tubular joints in offshore steel structures is studied. Two test series on full-scale tubular joints have been carried through. One series was on joints in conventional offshore structural steel, and the other series was on joints in high-strength...... steel with a yield stress of 820-830 MPa and with high weldability and toughness properties. The test specimens of both series had the same geometry. The present report concentrates on the results obtained in the investigation on the high-strength steel tubular joints.The test specimens were fabricated...... amplitude fatigue test results showed shorter fatigue lives in variable amplitude loading than should be expected from the linear fatigue damage accumulation formula. Furthermore, the fatigue tests on high-strength steel tubular joints showed slightly longer fatigue lives than those obtained...

  12. Low and high frequency fatigue tests of nodular cast irons

    Directory of Open Access Journals (Sweden)

    A. Vaško

    2017-01-01

    Full Text Available The paper deals with the comparison of fatigue properties of nodular cast iron at low and high frequency cyclic loading. The specimens from three melts of nodular cast iron with different microstructure and mechanical properties were used for experiments. Fatigue tests were carried out at low and high frequency sinusoidal cyclic push-pull loading (stress ratio R = –1 at ambient temperature (T = 20 ± 5 °C. Low frequency fatigue tests were carried out using the fatigue experimental machine Zwick/Roell Amsler 150HFP 5100 at frequency f ≈ 120 Hz; high frequency fatigue tests were carried out using the ultrasonic fatigue testing device KAUP-ZU at frequency f ≈ 20 kHz.

  13. Effectiveness, Mediators, and Effect Predictors of Internet Interventions for Chronic Cancer-Related Fatigue : The Design and an Analysis Plan of a 3-Armed Randomized Controlled Trial

    NARCIS (Netherlands)

    Wolvers, Marije Dj; Bruggeman-Everts, Fieke Z; Van der Lee, Marije L; Van de Schoot, Rens; Vollenbroek-Hutten, Miriam Mr

    2015-01-01

    BACKGROUND: Internet interventions offer advantages that especially cancer survivors who suffer from fatigue could benefit from. Given the growing number of such patients, Internet interventions could supplement and strengthen currently available health care. OBJECTIVE: This paper describes the desi

  14. Characteristics of advanced cancer patients with cancer-related fatigue enrolled in clinical trials and patients referred to outpatient palliative care clinics

    National Research Council Canada - National Science Library

    Yennurajalingam, Sriram; Kang, Jung Hun; Cheng, Huai Yong; Chisholm, Gary B; Kwon, Jung Hye; Palla, Shana L; Bruera, Eduardo

    2013-01-01

    ...) differ from patients in outpatient palliative care clinics (OPCs). The primary aim of this study was to compare the characteristics of two groups of patients with advanced cancer and moderate-to-severe fatigue...

  15. Cancer-Related Fatigue and Rehabilitation: A Randomized Controlled Multicenter Trial Comparing Physical Training Combined With Cognitive-Behavioral Therapy With Physical Training Only and With No Intervention

    OpenAIRE

    Van Weert, E.; May, A. M.; Korstjens, I.; Post, W.J.; van der Schans, C. P.; van den Borne, B; Mesters, I.; Ros, W J G; Hoekstra-Weebers, J.E.H.M.

    2010-01-01

    textabstractBackground. Research suggests that cancer rehabilitation reduces fatigue in survivors of cancer. To date, it is unclear what type of rehabilitation is most beneficial. Objective. This randomized controlled trial compared the effect on cancerrelated fatigue of physical training combined with cognitive behavioral therapy with physical training alone and with no intervention. Design. In this multicenter randomized controlled trial, 147 survivors of cancer were randomly assigned to a ...

  16. Flex Fatigue Property and Fractography of High Performance Fibers

    Institute of Scientific and Technical Information of China (English)

    ZHANG Hua-peng; LIU Xiao-yan; SHI Mei-wu; ZHANG Jian-chun; LAI Kan; WANG Shan-yuan

    2002-01-01

    The effects of pre-stress and bending angle on the flex fatigue lifetimes of para- aramds have been studied choosing the Twaron 2000 high performance filament as the studying subject by use of the self-developed flex fatigue apparatus. The fractography of the fatiguebreaking end of the single filaments has been obtained and the fatigue-breaking mechanisms have been analyzed using the LM and SEM. The differences of the fatigue properties and fractography of a variety of high performance fibers such as Kevlar 129, Kevlar 29 and UHMW PE have been discussed.

  17. Investigation analysis of current exercise status and its obstacle factors in patients with cancer-related fatigue%癌因性疲乏患者运动现状及障碍因素的调查分析

    Institute of Scientific and Technical Information of China (English)

    王晓庆; 段培蓓; 杨丽华; 梅思娟

    2015-01-01

    目的 了解患有癌因性疲乏的胃肠道肿瘤患者的运动情况,分析其障碍因素,为临床护理工作提供依据. 方法 采用自行设计的一般资料调查问卷及肿瘤患者运动障碍问卷对江苏省中医院消化肿瘤外科的216例胃肠道肿瘤并具有不同程度癌因性疲乏的患者进行问卷调查. 结果 216例患者中有155例进行运动,但只有66例运动强度达到了美国肿瘤学会2012年发布的运动指南推荐的标准."不知道运动能够减轻疲乏程度""害怕运动对疾病及治疗带来负面影响""疲乏""缺乏运动技能"及"无运动习惯"等是影响癌因性疲乏患者实施运动疗法的主要障碍因素. 结论 医护人员应意识到癌因性疲乏对肿瘤患者生活质量的严重影响,规范化评估和管理疲乏,进行睡眠干预和行为指导,科学地评价疲乏的管理效果.%Objective To probe into the exercise status of digestive tumor patients in cancer-related fatigue, analyze its obstacle factors, in order to provide evidence for clinical nursing care. Methods Self designed general information questionnaire and tumor patient′s cinesipathy questionnaire in 216 digestive tumor patients of Digestive Tumor Surgery Department in Jiangsu Chinese Medicine Hospital for investigation of different degree cancer-related fatigue. Results A total of 155 of 216 patients had excises, but 66 cases reached the excises intensity of American Cancer Society in 2012 published guidelines recommend movement standards;"do not know that exercise can reduce fatigue degree", "fear campaign negative impact on disease and treatment","tired", "lack of motor skills" and "no exercise habits" were the obstacle factors for cancer-related fatigue carrying out exercise therapy. Conclusions Medical personnel should be aware of the impact of cancer-related fatigue on the quality of life in the cancer patients, regulate assessment and manage fatigue, carry out sleep interventions and guide

  18. Fatigue life of high strength steel for cold forming

    Directory of Open Access Journals (Sweden)

    R. Ulewicz

    2017-01-01

    Full Text Available The article presents the results of fatigue tests carried out on STRENX-type high-strength cold forming steel. For high-cycle fatigue tests carried out using low cycle loading frequencies of around 30 Hz, a ROTOFLEX machine was used. For ultra high-cycle tests, a KAUP-ZU testing machine was employed, which enables fatigue tests to be performed with symetric specimen loading (R = -1 and at a frequency of f ≈ 20 kHz. The relationships σa = f(N were determined experimentally in the high and ultra high-cycle region for STRENX high-strength steel. To determine the fatigue crack initiation mechanism, the fractographic analysis of fatigue fractures was made.

  19. A multimodal physiotherapy programme plus deep water running for improving cancer-related fatigue and quality of life in breast cancer survivors.

    Science.gov (United States)

    Cuesta-Vargas, A I; Buchan, J; Arroyo-Morales, M

    2014-01-01

    The aim of the study was to assess the feasibility and effectiveness of aquatic-based exercise in the form of deep water running (DWR) as part of a multimodal physiotherapy programme (MMPP) for breast cancer survivors. A controlled clinical trial was conducted in 42 primary breast cancer survivors recruited from community-based Primary Care Centres. Patients in the experimental group received a MMPP incorporating DWR, 3 times a week, for an 8-week period. The control group received a leaflet containing instructions to continue with normal activities. Statistically significant improvements and intergroup effect size were found for the experimental group for Piper Fatigue Scale-Revised total score (d = 0.7, P = 0.001), as well as behavioural/severity (d = 0.6, P = 0.05), affective/meaning (d = 1.0, P = 0.001) and sensory (d = 0.3, P = 0.03) domains. Statistically significant differences between the experimental and control groups were also found for general health (d = 0.5, P quality of life (d = 1.3, P quality of life in breast cancer survivors. Further, the high level of adherence and lack of adverse events indicate such a programme is safe and feasible. © 2013 John Wiley & Sons Ltd.

  20. High temperature fatigue behavior of tungsten copper composites

    Science.gov (United States)

    Verrilli, M. J.; Kim, Y.-S.; Gabb, T. P.

    1990-01-01

    The present study investigates the high-temperature fatigue behavior of a 9-v/o tungsten fiber-reinforced copper matrix composite. Load-controlled isothermal fatigue at 260 and 560 C and thermomechanical fatigue (TMF) experiments, both in-phase and out-of-phase between 260 and 560 C, were performed. The stress-strain response under all conditions displayed considerable inelasticity. Strain ratchetting was observed during all the fatigue experiments. For the isothermal fatigue and in-phase TMF tests, the ratchetting was always in a tensile direction, continuing until failure. The ratchetting during the out-of-phase TMF test shifted from a tensile to a compressive direction. For all cases, the fatigue lives were found to be controlled by the damage of the copper matrix. On a stress basis, TMF loading substantially reduced lives relative to isothermal cycling.

  1. The role of creep in high temperature low cycle fatigue.

    Science.gov (United States)

    Manson, S. S.; Halford, G. R.; Spera, D. A.

    1971-01-01

    The significance of the role that creep can play in governing high-temperature, low-cycle fatigue resistance is investigated by conducting strain cycling tests on two high-temperature stainless steel alloys and making concurrent measurements of stress, temperature, and strain at various frequencies. The results are then analyzed in terms of damage imposed by creep and fatigue components. It is shown that creep can play an important and sometimes dominant role in low cycle fatigue at high temperatures. The results of the study include the findings that: (1) the simple life-fraction theory described is adequate for calculating creep damage when the cyclic creep rupture curve is used as a basis for analysis; (2) a method of universal slopes originally developed for room temperature use is sufficiently accurate at high temperature to be used to calculate pure fatigue damage; and (3) a linear creep-fatigue damage rule can explain the transitions observed from one failure mode to another.

  2. 音乐疗法对临终肿瘤患者癌因性疲乏的影响%Inlfuence of the music therapy on the cancer-related fatigue of the terminal tumor patients

    Institute of Scientific and Technical Information of China (English)

    吴玉华; 冷海燕; 张佩文

    2015-01-01

    Objective:To discuss the inlfuence of the music therapy on the cancer-related fatigue and life quality of the terminal tumor patients. Methods:From Jan. to Oct. 2014, 100 cancer patients in the hospice care ward were selected and divided into a test group and a control one with 50 cases each. The control group was given the conventional treatment and care, and the test group was added with the music therapy intervention, 30 minutes each time, 1 time/d. Results:The degree of the cancer-related fatigue was signiifcantly reduced after the intervention than before in the experimental group (P<0.05), and the overall quality of the life was (46±13.11) points which was higher than (36 ±8.84) points in the control group, (Z=-4.276, P<0.05). Conclusion:The music therapy can eliminate the cancer-related fatigue or alleviate tiredness level of the terminal tumor patients so as to improve their life quality.%目的:探讨音乐疗法对临终肿瘤患者癌因性疲乏和生活质量的影响。方法:选择2014年1-10月舒缓疗护病区癌症患者100例,分为试验组和对照组各50例。对照组给予常规治疗和护理,试验组增加音乐疗法干预,每次30 min,每天1次。结果:干预后试验组癌因性疲乏程度较干预前明显减轻(P<0.05);总体生活质量为(46±13.11)分,高于对照组的(36±8.84)分(Z=-4.276,P<0.05)。结论:音乐疗法可消除临终肿瘤患者癌因性疲乏或缓解疲乏程度,从而提高患者的生活质量。

  3. 正念减压法对癌因性疲乏干预效果的系统评价%Systematic evaluation for the effectiveness of cancer related fatigue intervention by mindfulness-based stress reduction

    Institute of Scientific and Technical Information of China (English)

    田利; 胡雁; 李惠玲; 邢唯杰

    2015-01-01

    目的:系统评价正念减压法干预癌因性疲乏的有效性。方法计算机检索PubM ed、M edline、EM base、Web of Science、Cochrane Central Register of Controlled T rials、CBM和万方数据库,查找关于正念减压法干预癌因性疲乏的相关研究文献,检索时限均从建库至2014年12月。由2位评价员按纳入与排除标准独立筛选文献、提取资料并评价质量后,采用RevMan 5.1软件进行Meta分析。结果共纳入3篇RCT ,381例患者。Meta分析结果显示:接受正念减压疗法组患者干预前后疲乏降低的程度与对照组患者相比,差异有统计学意义[SMD=-0.36,95% CI(-0.53,-0.20),P<0.0001]。结论现有证据表明,正念减压法训练能缓解癌因性疲乏。鉴于纳入研究数量有限,上述结论尚需开展更多研究予以验证。%Objective To evaluate the effectiveness of the effectiveness of cancer related fatigue intervention by mindful‐ness‐based stress reduction .Method Systematic searches were carried out in PubMed ,Medline ,EMbase ,Web of Science , Cochrane Central Register of Controlled Trials ,CBM and Wanfang databases from their inception through December 2014 for relevant RCTs .Papers were screened ,data was extracted and quality appraised .The dates was analyzed by two review‐ers independently using predefined criteria and Review Manager Software (5 .0 .1 version) .Result Three RCTs (n=381 , participants) were included in the final meta‐analysis .Mindfulness‐based Stress Reduction(MBSR) has a moderate effect on cancer related fatigue compared with the usual care[SMD= -0 .36 ,95% CI(-0 .53 ,-0 .20) ,P<0 .0001] .Conclusion MBSR training could alleviate cancer relate fatigue from this meta‐analysis .However ,in view of current limited trials ,fur‐ther research is recommended to contribute further evidence .

  4. Very high cycle fatigue testing of concrete using ultrasonic cycling

    Energy Technology Data Exchange (ETDEWEB)

    Karr, Ulrike; Schuller, Reinhard; Fitzka, Michael; Mayer, Herwig [Univ. of Natural Resources and Life Sciences, Vienna (Austria). Inst. of Physics and Materials Science; Denk, Andreas; Strauss, Alfred [Univ. of Natural Resources and Life Sciences, Vienna (Austria)

    2017-06-01

    The ultrasonic fatigue testing method has been further developed to perform cyclic compression tests with concrete. Cylindrical specimens vibrate in resonance at a frequency of approximately 20 kHz with superimposed compressive static loads. The high testing frequency allows time-saving investigations in the very high cycle fatigue regime. Fatigue tests were carried out on ''Concrete 1'' (compressive strength f{sub c} = 80 MPa) and ''Concrete 2'' (f{sub c} = 107 MPa) under purely compressive loading conditions. Experiments at maximum compressive stresses of 0.44 f{sub c} (Concrete 1) and 0.38 f{sub c} (Concrete 2) delivered specimen failures above 109 cycles, indicating that no fatigue limit exists for concrete below one billion load cycles. Resonance frequency, power required to resonate the specimen and second order harmonics of the vibration are used to monitor fatigue damage in situ. Specimens were scanned by X-ray computed tomography prior to and after testing. Fatigue cracks were produced by ultrasonic cycling in the very high cycle fatigue regime at interfaces of grains as well as in cement. The possibilities as well as limitations of ultrasonic fatigue testing of concrete are discussed.

  5. A criterion for high-cycle fatigue life and fatigue limit prediction in biaxial loading conditions

    Institute of Scientific and Technical Information of China (English)

    ukasz Pejkowski; Dariusz Skibicki

    2016-01-01

    This paper presents a criterion for high-cycle fatigue life and fatigue strength estimation under periodic proportional and non-proportional cyclic loading. The cri-terion is based on the mean and maximum values of the second invariant of the stress deviator. Important elements of the criterion are: function of the non-proportionality of fatigue loading and the materials parameter that expresses the materials sensitivity to non-proportional loading. The methods for the materials parameters determination uses three S–N curves: tension–compression, torsion, and any non-proportional loading proposed. The criterion has been verified using experimental data, and the results are included in the paper. These results should be considered as promis-ing. The paper also includes a proposal for multiaxial fatigue models classification due to the approach for the non-proportionality of loading.

  6. Material fatigue in high pressure piping

    Energy Technology Data Exchange (ETDEWEB)

    Brunne, W.C. [Pro Novum, Research and Technological Services, Ltd, Katowice, (Poland)

    1998-12-31

    The present paper describes a type of damage to four-way cross pieces on live steam and reheated steam pipelines. The results of metallographic examination and strength tests are presented. The occurring mechanisms of material degradation, i.e. low-cycle fatigue and hydrogen corrosion are discussed. The both mechanisms result in the corrosion fatigue of the material causing the failure of cross pieces. A new design of cross piece was proposed. (orig.) 5 refs.

  7. 肺癌术后化疗患者癌因性疲乏的护理干预分析%Analysis of nursing intervention about cancer-related fatigue in lung cancer patients with postoperative chemotherapy

    Institute of Scientific and Technical Information of China (English)

    陈伟连; 董彩兰; 张维婷; 钟丽

    2013-01-01

    Objective To investigate nursing intervention measures of cancer-related fatigue in lung cancer patients with postoperative chemotherapy. Methods 72 lung cancer patients with postoperative chemotherapy were randomly divided into two groups.Both control group and experimental group were 36 cases. The control group received conventional care,and experimental group were given to tar-geted care.Comparing the piper fatigue scale score ,self-rating depression scale score and quality of sleep between the two groups. Results The piper fatigue scale score and self-rating depression scale score of the experimental group patients were low, and the quality of sleep was better.The differences showed a statistical significance (P<0.05). Conclusion The effect of targeted care was good towards cancer-related fatigue in lung cancer patients with postoperative chemotherapy,which can improve the quality of life and was worth to application.%目的:探讨肺癌手术后化疗患者癌因性疲乏的护理干预对策。方法选取本院72例肺癌手术后化疗患者为研究对象,随机分为对照组和实验组,每组36例,对照组给予常规护理,实验组给予针对性护理,对比观察2组患者的piper疲乏量表得分、抑郁自评量表得分及患者睡眠质量。结果干预后实验组患者piper疲乏量表得分低、抑郁自评量表得分低,患者睡眠质量更好,与对照组比较差异有统计学意义(P<0.05)。结论在肺癌手术后化疗患者癌因性疲乏期间给予针对性护理可以提高患者生活质量,值得应用。

  8. On high-cycle fatigue of 316L stents.

    Science.gov (United States)

    Barrera, Olga; Makradi, Ahmed; Abbadi, Mohammed; Azaouzi, Mohamed; Belouettar, Salim

    2014-01-01

    This paper deals with fatigue life prediction of 316L stainless steel cardiac stents. Stents are biomedical devices used to reopen narrowed vessels. Fatigue life is dominated by the cyclic loading due to the systolic and diastolic pressure and the design against premature mechanical failure is of extreme importance. Here, a life assessment approach based on the Dang Van high cycle fatigue criterion and on finite element analysis is applied to explore the fatigue reliability of 316L stents subjected to multiaxial fatigue loading. A finite element analysis of the stent vessel subjected to cyclic pressure is performed to carry out fluctuating stresses and strain at some critical elements of the stent where cracks or complete fracture may occur. The obtained results show that the loading path of the analysed stent subjected to a pulsatile load pressure is located in the safe region concerning infinite lifetime.

  9. Spectral Fatigue Analysis of Jacket Stuctures in Mumbai High Field

    Directory of Open Access Journals (Sweden)

    S. Nallayarasu

    2010-09-01

    Full Text Available Fatigue analysis of offshore structures is an integral part of design of offshore structures and shall be carried out with suitable method of discretising the seastate. Historically, for most of the fixed offshore structures, deterministic fatigue analysis found to predict the fatigue damage reasonably well and has been in use for several decades. Fixed structures with small topsides, mostly exhibit a static response characteristics and the natural period may be in the order of less than 2 seconds. Offshore platforms with larger production capacity and deeper water depths may require specialised treatment of seastate due to their dynamic characteristics more vulnerable for fatigue damage. A spectral fatigue analysis has been performed for two different platforms in Mumbai high field (MNP and RS14 and a comparison is made with deterministic analysis. The spectral fatigue analysis indicates that the predicted fatigue life is lower than the deterministic analysis since the dynamic amplification of wave loads are treated approximately in deterministic analysis. Hence for large structures, it recommended to use spectral methods to assess the fatigue life of tubular joints.

  10. High-Frequency Axial Fatigue Test Procedures for Spectrum Loading

    Science.gov (United States)

    2016-07-20

    REPORT NO: NAWCADPAX/TIM-2016/49 HIGH - FREQUENCY AXIAL FATIGUE TEST PROCEEDURES FOR SPECTRUM LOADING by David T. Rusk, AIR...OF THE NAVY NAVAL AIR WARFARE CENTER AIRCRAFT DIVISION PATUXENT RIVER, MARYLAND NAWCADPAX/TIM-2016/49 20 July 2016 HIGH - FREQUENCY AXIAL...Technical Information Memorandum 3. DATES COVERED 4. TITLE AND SUBTITLE High - Frequency Axial Fatigue Test Procedures for Spectrum Loading

  11. High-speed Stochastic Fatigue Testing

    DEFF Research Database (Denmark)

    Brincker, Rune; Sørensen, John Dalsgaard

    1990-01-01

    Good stochastic fatigue tests are difficult to perform. One of the major reasons is that ordinary servohydraulic loading systems realize the prescribed load history accurately at very low testing speeds only. If the speeds used for constant amplitude testing are applied to stochastic fatigue...... the analog control device remain as the basic control mechanism in the system, but distorting the input signal by computer in order to minimize the errors of the load history extremes. The principle proves to be very efficient to reduce all kinds of system errors and has shown to be able to increase...

  12. Competition between microstructure and defect in multiaxial high cycle fatigue

    Directory of Open Access Journals (Sweden)

    F. Morel

    2015-07-01

    Full Text Available This study aims at providing a better understanding of the effects of both microstructure and defect on the high cycle fatigue behavior of metallic alloys using finite element simulations of polycrystalline aggregates. It is well known that the microstructure strongly affects the average fatigue strength and when the cyclic stress level is close to the fatigue limit, it is often seen as the main source of the huge scatter generally observed in this fatigue regime. The presence of geometrical defects in a material can also strongly alter the fatigue behavior. Nonetheless, when the defect size is small enough, i.e. under a critical value, the fatigue strength is no more affected by the defect. The so-called Kitagawa effect can be interpreted as a competition between the crack initiation mechanisms governed either by the microstructure or by the defect. Surprisingly, only few studies have been done to date to explain the Kitagawa effect from the point of view of this competition, even though this effect has been extensively investigated in the literature. The primary focus of this paper is hence on the use of both FE simulations and explicit descriptions of the microstructure to get insight into how the competition between defect and microstructure operates in HCF. In order to account for the variability of the microstructure in the predictions of the macroscopic fatigue limits, several configurations of crystalline orientations, crystal aggregates and defects are studied. The results of each individual FE simulation are used to assess the response at the macroscopic scale thanks to a probabilistic fatigue criterion proposed by the authors in previous works. The ability of this criterion to predict the influence of defects on the average and the scatter of macroscopic fatigue limits is evaluated. In this paper, particular emphasis is also placed on the effect of different loading modes (pure tension, pure torsion and combined tension and torsion on

  13. Localized bending fatigue behavior of high-strength steel monostrands

    DEFF Research Database (Denmark)

    Winkler, Jan; Fischer, Gregor; Georgakis, Christos T.

    2012-01-01

    In this paper, the localized bending fatigue behavior of pretensioned high strength steel monostrands is investigated. Furthermore, a new methodology using an optical photogrammetry system, which can quantify surface deformations on the strand is presented. The system allows measurement of the st......In this paper, the localized bending fatigue behavior of pretensioned high strength steel monostrands is investigated. Furthermore, a new methodology using an optical photogrammetry system, which can quantify surface deformations on the strand is presented. The system allows measurement...

  14. Iyengar-Yoga Compared to Exercise as a Therapeutic Intervention during (Neoadjuvant Therapy in Women with Stage I–III Breast Cancer: Health-Related Quality of Life, Mindfulness, Spirituality, Life Satisfaction, and Cancer-Related Fatigue

    Directory of Open Access Journals (Sweden)

    Désirée Lötzke

    2016-01-01

    Full Text Available This study aims to test the effects of yoga on health-related quality of life, life satisfaction, cancer-related fatigue, mindfulness, and spirituality compared to conventional therapeutic exercises during (neoadjuvant cytotoxic and endocrine therapy in women with breast cancer. In a randomized controlled trial 92 women with breast cancer undergoing oncological treatment were randomly enrolled for a yoga intervention (YI (n=45 or for a physical exercise intervention (PEI (n=47. Measurements were obtained before (t0 and after the intervention (t1 as well as 3 months after finishing intervention (t2 using standardized questionnaires. Life satisfaction and fatigue improved under PEI (p<0.05 but not under YI (t0 to t2. Regarding quality of life (EORTC QLQ-C30 a direct effect (t0 to t1; p<0.001 of YI was found on role and emotional functioning, while under PEI only emotional functioning improved. Significant improvements (p<0.001 were observed at both t1 and t2 also for symptom scales in both groups: dyspnea, appetite loss, constipation, and diarrhea. There was no significant difference between therapies for none of the analyzed variables neither for t1 nor for t2. During chemotherapy, yoga was not seen as more helpful than conventional therapeutic exercises. This does not argue against its use in the recovery phase.

  15. FATIGUE STRENGTH OF HIGH-STRENGTH STEEL,

    Science.gov (United States)

    coldhardened by deforming to 83%. It was found that it has low static notch sensitivity (lower than that of heat-treated steels), that static strength ...is raised appreciably by increased cold plastic deformation, and that its fatigue strength is raised substantially by mechanical polishing. (Author)

  16. Fatigue in high-speed aluminium craft: A design methodology for predicting the fatigue life

    NARCIS (Netherlands)

    Tuitman, J.T.; Hoogendoorn, D.

    2013-01-01

    Within the VOMAS project, a methodology has been developed to predict the fatigue life of high-speed aluminium crafts. This paper describes this methodology and its implementation into a computational tool. This methodology computes the seakeeping and resulting pressure at the structure for all cond

  17. Nanoplatforms for highly sensitive fluorescence detection of cancer-related proteases.

    Science.gov (United States)

    Wang, Hongwang; Udukala, Dinusha N; Samarakoon, Thilani N; Basel, Matthew T; Kalita, Mausam; Abayaweera, Gayani; Manawadu, Harshi; Malalasekera, Aruni; Robinson, Colette; Villanueva, David; Maynez, Pamela; Bossmann, Leonie; Riedy, Elizabeth; Barriga, Jenny; Wang, Ni; Li, Ping; Higgins, Daniel A; Zhu, Gaohong; Troyer, Deryl L; Bossmann, Stefan H

    2014-02-01

    Numerous proteases are known to be necessary for cancer development and progression including matrix metalloproteinases (MMPs), tissue serine proteases, and cathepsins. The goal of this research is to develop an Fe/Fe3O4 nanoparticle-based system for clinical diagnostics, which has the potential to measure the activity of cancer-associated proteases in biospecimens. Nanoparticle-based "light switches" for measuring protease activity consist of fluorescent cyanine dyes and porphyrins that are attached to Fe/Fe3O4 nanoparticles via consensus sequences. These consensus sequences can be cleaved in the presence of the correct protease, thus releasing a fluorescent dye from the Fe/Fe3O4 nanoparticle, resulting in highly sensitive (down to 1 × 10(-16) mol l(-1) for 12 proteases), selective, and fast nanoplatforms (required time: 60 min).

  18. 系统化护理干预对癌因性疲乏患者影响的Meta分析%Meta-Analysis of Systematic Nursing Intervention on Patients with Cancer Related Fatigue

    Institute of Scientific and Technical Information of China (English)

    阿依古丽·买买提; 佟宛云; 韩记真

    2013-01-01

    目的系统评价系统化护理干预对癌因性疲乏(cancer-related fatigue,CRF)患者的影响。方法以“癌症”、“疲乏”、“系统化护理”等为关键词,计算机检索中国生物医学文献数据库(CBM)、中国期刊全文数据库(CNKI)、维普数据库(VIP)及万方数据库,检索日期为数据库建立至2012年12月1日;纳入系统化护理干预 CRF患者的随机对照试验(RCT),由2名评价者独立评价纳入研究的质量并提取资料,并用 RevMan 5.0统计软件进行Meta分析。结果共纳入9篇文献,包括1042例CRF患者,所有研究均采用了随机对照的方法,但未明确是否采用分配隐藏或双盲。Meta分析结果显示,通过护理干预后,系统护理干预组无疲乏及轻度疲乏患者明显多于常规护理组,差异具有统计学意义(RR 合并=4.72,P <0.01,95%CI =3.58~6.24);系统化护理对CRF患者的生活质量的影响,与常规护理比较,差异具有统计学意义(RR 合并=9.67,P =0.003,95%CI =3.30~16.04);经干预后系统化护理组CRF患者的卡氏功能(KPS)评分明显低于常规护理组患者,差异具有统计学意义(RR 合并=4.22,P<0.01,95%CI =2.06~6.38)。结论针对CRF患者进行护理,系统化护理干预明显优于常规护理模式,可改善CRF患者疲乏状态、生活质量等。%Objective To evaluate the systematic nursing intervention on patients with cancer related fatigue(Cancer-related Fatigue CRF).Methods “Cancer”,“Fatigue”,“Systematic Nursing”as key words, computer retrieval Chinese Biomedical Literature Database (CBM),Chinese Journal Full-text Database (CNKI),VIP database(VIP)and Wanfang database,retrieve date established for the database to Decem-ber 1,2012;systematic nursing intervention in patients with CRF included randomized controlled trials (RCT),2 reviewers independently

  19. Fatigue behavior of the magnesium alloy ZK60 in high cycle fatigue

    NARCIS (Netherlands)

    Constantinescu, D.M.; Moldovan, P.; Sillekens, W.H.; Sandu, M.; Apostol, D.A.; Miron, M.C.

    2009-01-01

    Not too much information is available in the literature for establishing fatigue properties of magnesium alloys. A compilation of existing fatigue and fatigue crack growth data of different Mg-alloys has been published by ASM International. One can underline that fatigue properties of some of the st

  20. 护理干预对乳腺癌癌性疲乏患者生活质量的影响%The effect of nursing intervention on life quality of breast cancer patient with cancer-related fatigue

    Institute of Scientific and Technical Information of China (English)

    刘小梅

    2014-01-01

    To investigate the effect of nursing intervention on life quality of breast cancer patient with cancer-related fatigue. Methods:100 cases were divided into two groups,the observation group were received nursing intervention,the control group were implemented routine care,then Piper fatigue Scale combined coping Scale scores after intervention and satisfaction with care and quality of life were compared in the two groups. Results:The observation group with behavior and severity,emotional,sensory,and cognitive and emotional coping scores were lower than control group (P<0. 05). The observation group after intervention with activity healthy feelings,daily life,life experience and family support score were all rised,and all were higher than control group after the intervention (P<0. 05). The nursing service,nursing skills,psychological care,inpatient environment satisfaction were higher than control group (P<0. 05). Conclusion:Nursing intervention on breast cancer with cancer-related fatigue can promote a more positive attitude in the face of breast canc-er,while improving the life quality and increasing nurse-patient relationship,so it can improve nursing satisfaction.%目的:探讨护理干预对乳腺癌癌性疲乏患者生活质量的影响。方法:选择我院2009年1月~2012年12月收治的乳腺癌患者100例,将其随机等分为观察组和对照组。观察组实施护理干预方法,对照组则实施常规护理,如体位护理、饮食干预、一般护理、心理干预等,比较两组患者干预后Piper疲乏量表结合应对量表得分情况、生活质量及对护理工作满意度。结果:观察组行为及严重程度、情感、感觉、认知及情绪应对量表得分低于对照组(P<0.05),活动能力、健康感受、日常生活、生活感受及家庭支持得分高于对照组(P<0.05),患者对护理服务、护理技术、心理关怀、住院环境满意度高于对照组(P<0.05)。结论:护理干预能促使

  1. Muscle fatigue during high-intensity exercise in children.

    Science.gov (United States)

    Ratel, Sébastien; Duché, Pascale; Williams, Craig A

    2006-01-01

    Children are able to resist fatigue better than adults during one or several repeated high-intensity exercise bouts. This finding has been reported by measuring mechanical force or power output profiles during sustained isometric maximal contractions or repeated bouts of high-intensity dynamic exercises. The ability of children to better maintain performance during repeated high-intensity exercise bouts could be related to their lower level of fatigue during exercise and/or faster recovery following exercise. This may be explained by muscle characteristics of children, which are quantitatively and qualitatively different to those of adults. Children have less muscle mass than adults and hence, generate lower absolute power during high-intensity exercise. Some researchers also showed that children were equipped better for oxidative than glycolytic pathways during exercise, which would lead to a lower accumulation of muscle by-products. Furthermore, some reports indicated that the lower ability of children to activate their type II muscle fibres would also explain their greater resistance to fatigue during sustained maximal contractions. The lower accumulation of muscle by-products observed in children may be suggestive of a reduced metabolic signal, which induces lower ratings of perceived exertion. Factors such as faster phosphocreatine resynthesis, greater oxidative capacity, better acid-base regulation, faster readjustment of initial cardiorespiratory parameters and higher removal of metabolic by-products in children could also explain their faster recovery following high-intensity exercise.From a clinical point of view, muscle fatigue profiles are different between healthy children and children with muscle and metabolic diseases. Studies of dystrophic muscles in children indicated contradictory findings of changes in contractile properties and the muscle fatigability. Some have found that the muscle of boys with Duchenne muscular dystrophy (DMD) fatigued less

  2. 肾癌患者术后癌因性疲乏与睡眠质量的相关性研究%Relationship between postoperative cancer-related fatigue and sleep quality in patients with renal carcinoma

    Institute of Scientific and Technical Information of China (English)

    程一书; 汪勇

    2015-01-01

    [Objective] To study the degree of cancer-related fatigue (CRF) of patients with renal carcinoma,analyze the relationship between CRF and sleep quality,and provide the basis for comprehensive management of CRF in patients with renal carcinoma.[Methods] 288 patients with renal carcinoma,who were treated in Clinical Medical College of the Hubei University of Science and Technology from January 2013 to August 2014,were enrolled into this study.The fatigue symptoms of patients were assessed by the Piper fatigue scale (PFS),and the sleep quality was evaluated by the Pittsburgh sleep quality index (PSQI).[Results] The average PFS scores of 288 patients with renal carcinoma were (2.77±1.36),and there were statistically significant differences in perception dimension scores and average PFS scores among different age groups (P<0.05).The average PSQI scores were (7.47±3.41),and there was statistically significant difference in sleep quality among different cancer degree groups (P<0.05).There was a significant positive correlation between PFS and PSQI scores in patients with renal carcinoma.[Conclusion] PFS is suitable for evaluating the fatigue symptoms in patients with renal carcinoma,and CRF is closely related to sleep quality.It is necessary to carry out the comprehensive management measures to reduce the fatigue symptoms in patients with renal carcinoma,to improve the prognosis.%目的 研究肾癌患者癌因性疲乏(CRF)程度,探讨其与睡眠质量的关系,为肾癌患者CRF综合管理提供依据.方法 选择湖北科技学院临床医学院2013年1月-2014年8月收治的肾癌患者288例作为研究对象.采用Piper(PFS)疲乏量表对患者疲乏症状进行评价,使用匹兹堡睡眠质量指数(PSQI)量表评估患者睡眠情况.结果 288名肾癌患者PFS平均得分为(2.77±1.36)分,不同年龄段肾癌患者感知维度、PFS均值得分差异具有统计学意义(P<0.05);PSQI平均得分为(7.47±3.41)分,不同程度CRF肾癌患者睡

  3. A Modified Fatigue Damage Model for High-Cycle Fatigue Life Prediction

    Directory of Open Access Journals (Sweden)

    Meng Wang

    2016-01-01

    Full Text Available Based on the assumption of quasibrittle failure under high-cycle fatigue for the metal material, the damage constitutive equation and the modified damage evolution equation are obtained with continuum damage mechanics. Then, finite element method (FEM is used to describe the failure process of metal material. The increment of specimen’s life and damage state can be researched using damage mechanics-FEM. Finally, the lifetime of the specimen is got at the given stress level. The damage mechanics-FEM is inserted into ABAQUS with subroutine USDFLD and the Python language is used to simulate the fatigue process of titanium alloy specimens. The simulation results have a good agreement with the testing results under constant amplitude loading, which proves the accuracy of the method.

  4. High-cycle Fatigue Fracture Behavior of Ultrahigh Strength Steels

    Institute of Scientific and Technical Information of China (English)

    Weijun HUI; Yihong NIE; Han DONG; Yuqing WENG; Chunxu WANG

    2008-01-01

    The fatigue fracture behavior of four ultrahigh strength steels with different melting processes and therefore different inclusion sizes were studied by using a rotating bar two-point bending fatigue machine in the high-cycle regime up to 107 cycles of loading. The fracture surfaces were observed by field emission scanning electron microscopy (FESEM). It was found that the size of inclusion has significant effect on the fatigue behavior.For AISI 4340 steel in which the inclusion size is smaller than 5.5 μm, all the fatigue cracks except one did not initiated from inclusion but from specimen surface and conventional S-N curve exists. For 65Si2MnWE and Aermet 100 steels in which the average inclusion sizes are 12.2 and 14.9 μm, respectively, fatigue cracks initiated from inclusions at lower stress amplitudes and stepwise S-N curves were observed. The S-N curvedisplays a continuous decline and fatigue failures originated from large oxide inclusion for 60Si2CrVA steel in which the average inclusion size is 44.4 μm. In the case of internal inclusion-induced fractures at cycles beyond about 1×106 for 65Si2MnWE and 60Si2CrVA steels, inclusion was always found inside the fish-eye and a granular bright facet (GBF) was observed in the vicinity around the inclusion. The GBF sizes increasewith increasing the number of cycles to failure Nf in the long-life regime. The values of stress intensity factor range at crack initiation site for the GBF are almost constant with Nf, and are almost equal to that for the surface inclusion and the internal inclusion at cycles lower than about 1×106. Neither fish-eye nor GBF was observed for Aermet 100 steel in the present study.

  5. Acute Inflammatory Response to Low-, Moderate-, and High-Load Resistance Exercise in Women With Breast Cancer-Related Lymphedema.

    Science.gov (United States)

    Cormie, Prue; Singh, Benjamin; Hayes, Sandi; Peake, Jonathan M; Galvão, Daniel A; Taaffe, Dennis R; Spry, Nigel; Nosaka, Kazunori; Cornish, Bruce; Schmitz, Kathryn H; Newton, Robert U

    2016-09-01

    Background Resistance exercise is emerging as a potential adjunct therapy to aid in the management of breast cancer-related lymphedema (BCRL). However, the mechanisms underlying the relationships between the acute and long-term benefits of resistance exercise on BCRL are not well understood. Purpose To examine the acute inflammatory response to upper-body resistance exercise in women with BCRL and to compare these effects between resistance exercises involving low, moderate, and high loads. The impact on lymphedema status and associated symptoms was also compared. Methods A total of 21 women, 62 ± 10 years old, with BCRL participated in the study. Participants completed low-load (15-20 repetition maximum [RM]), moderate-load (10-12 RM), and high-load (6-8 RM) exercise sessions consisting of 3 sets of 6 upper-body resistance exercises. Sessions were completed in a randomized order separated by a 7- to 10-day wash-out period. Venous blood samples were obtained to assess markers of exercise-induced muscle damage and inflammation. Lymphedema status was assessed using bioimpedance spectroscopy and arm circumferences, and associated symptoms were assessed using Visual Analogue Scales for pain, heaviness, and tightness. Measurements were conducted before and 24 hours after the exercise sessions. Results No significant changes in creatine kinase, C-reactive protein, interleukin-6, and tumor necrosis factor-α were observed following the 3 resistance exercise sessions. There were no significant changes in arm swelling or symptom severity scores across the 3 resistance exercise conditions. Conclusions The magnitude of acute exercise-induced inflammation following upper-body resistance exercise in women with BCRL does not vary between resistance exercise loads. © The Author(s) 2015.

  6. A model for high-cycle fatigue crack propagation

    Energy Technology Data Exchange (ETDEWEB)

    Balbi, Marcela Angela [Rosario National Univ. (Argentina); National Council of Scientific Research and Technology (CONICET) (Argentina)

    2017-02-01

    This paper deals with the prediction of high-cycle fatigue behavior for four different materials (7075-T6 alloy, Ti-6Al-4 V alloy, JIS S10C steel and 0.4 wt.-% C steel) using Chapetti's approach to estimate the fatigue crack propagation curve. In the first part of the paper, a single integral equation for studying the entire propagation process is determined using the recent results of Santus and Taylor, which consider a double regime of propagation (short and long cracks) characterized by the model of El Haddad. The second part of the paper includes a comparison of the crack propagation behavior model proposed by Navarro and de los Rios with the one mentioned in the first half of this work. The results allow us to conclude that the approach presented in this paper is a good and valid estimation of high-cycle fatigue crack propagation using a single equation to describe the entire fatigue crack regime.

  7. Anomolous Fatigue Crack Growth Phenomena in High-Strength Steel

    Science.gov (United States)

    Forth, Scott C.; James, Mark A.; Johnston, William M., Jr.; Newman, James C., Jr.

    2004-01-01

    The growth of a fatigue crack through a material is the result of a complex interaction between the applied loading, component geometry, three-dimensional constraint, load history, environment, material microstructure and several other factors. Previous studies have developed experimental and computational methods to relate the fatigue crack growth rate to many of the above conditions, with the intent of discovering some fundamental material response, i.e. crack growth rate as a function of something. Currently, the technical community uses the stress intensity factor solution as a simplistic means to relate fatigue crack growth rate to loading, geometry and all other variables. The stress intensity factor solution is a very simple linear-elastic representation of the continuum mechanics portion of crack growth. In this paper, the authors present fatigue crack growth rate data for two different high strength steel alloys generated using standard methods. The steels exhibit behaviour that appears unexplainable, compared to an aluminium alloy presented as a baseline for comparison, using the stress intensity factor solution.

  8. Effect of Qizaoyixue decoction with exercise on cancer-related fatigue for oophoroma patients during intermittent chemotherapy%芪枣益血汤加运动干预对卵巢癌患者化疗间歇期癌因性疲乏的效果

    Institute of Scientific and Technical Information of China (English)

    邱锡坚; 黄亦武; 许美华

    2011-01-01

    Objective To investigate the effect of Qizaoyixue decoction with exercise on cancer-related fatigue for oophoroma patients during intermittent chemotherapy.Methods 92 oophoroma patients with cancer-related fatigue were given diet intervention with exercise. They were investigated by Simple Fatigue Assessment Scale and European Organization for Research on Treatment of Cancer (EORTC)-QLQ-C30 for assessing their cancer-related fatigue and quality of life before the intervention and 30 days after the intervention with self-contrast method. Fatigue level and change of quality of life for them before and after the intervention were compared.Results Patients' fatigue was greatly relieved after the intervention;there was significant difference compared with that before the intervention (u=4.5,P<0.01). There was significant difference in quality of life compared with that before the intervention (P<0.01).Conclusions Qizaoyixue decoction with exercise could effectively relieve cancer-related fatigue for oophoroma patients during intermittent chemotherapy and improve their quality of life.%目的 探讨芪枣益血汤加运动干预对卵巢癌患者化疗间歇期的癌因性疲乏的效果.方法 对92例具有癌因性疲乏的卵巢癌患者进行饮食及运动干预,并采取自身对照方法,应用简易疲乏评估表、欧洲癌症治疗与研究组织问卷(EORTC-QLQ-C30),分别在干预前、干预30d后对患者进行癌因性疲乏和生活质量状况评估.观察干预前后患者疲乏缓解程度和生活质量的变化.结果 采用护理干预措施后,患者的疲乏程度有很大的缓解,与干预前比较差异有统计学意义(u=4.5,P<0.01);生活质量与干预前比较差异有统计学意义(P<0.01).结论 芪枣益血汤加运动干预能有效缓解卵巢癌患者的疲乏程度,并提高患者的生活质量.

  9. Dissipation Assessments During Dynamic Very High Cycle Fatigue Tests

    OpenAIRE

    2015-01-01

    International audience; This paper presents an experimental device developed to detect and estimate dissipated energy during very high cycle fatigue tests (VHCF) at high loading frequency (20 kHz) and low stress (i.e. far below the yield stress). Intrinsic dissipation is computed using local expressions of the heat diffusion equation and thermal data fields provided by an infrared focal plane array camera. The results obtained from tests performed on pure copper specimens show that dissipated...

  10. Probabilistic Material Strength Degradation Model for Inconel 718 Components Subjected to High Temperature, Mechanical Fatigue, Creep and Thermal Fatigue Effects

    Science.gov (United States)

    Bast, Callie Corinne Scheidt

    1994-01-01

    This thesis presents the on-going development of methodology for a probabilistic material strength degradation model. The probabilistic model, in the form of a postulated randomized multifactor equation, provides for quantification of uncertainty in the lifetime material strength of aerospace propulsion system components subjected to a number of diverse random effects. This model is embodied in the computer program entitled PROMISS, which can include up to eighteen different effects. Presently, the model includes four effects that typically reduce lifetime strength: high temperature, mechanical fatigue, creep, and thermal fatigue. Statistical analysis was conducted on experimental Inconel 718 data obtained from the open literature. This analysis provided regression parameters for use as the model's empirical material constants, thus calibrating the model specifically for Inconel 718. Model calibration was carried out for four variables, namely, high temperature, mechanical fatigue, creep, and thermal fatigue. Methodology to estimate standard deviations of these material constants for input into the probabilistic material strength model was developed. Using the current version of PROMISS, entitled PROMISS93, a sensitivity study for the combined effects of mechanical fatigue, creep, and thermal fatigue was performed. Results, in the form of cumulative distribution functions, illustrated the sensitivity of lifetime strength to any current value of an effect. In addition, verification studies comparing a combination of mechanical fatigue and high temperature effects by model to the combination by experiment were conducted. Thus, for Inconel 718, the basic model assumption of independence between effects was evaluated. Results from this limited verification study strongly supported this assumption.

  11. Getting the Facts: Cancer-Related Fatigue

    Science.gov (United States)

    ... and childcare. Often, family members or friends are happy to help because it is something concrete they ... those touched by this disease. LRF is the nation’s largest lymphoma-focused voluntary health organization devoted exclusively ...

  12. High temperature tension-compression fatigue behavior of a tungsten copper composite

    Science.gov (United States)

    Verrilli, Michael J.; Gabb, Timothy P.

    1990-01-01

    The high temperature fatigue of a (O)12 tungsten fiber reinforced copper matrix composite was investigated. Specimens having fiber volume percentages of 10 and 36 were fatigued under fully-reversed, strain-controlled conditions at both 260 and 560 C. The fatigue life was found to be independent of fiber volume fraction because fatigue damage preferentially occurred in the matrix. Also, the composite fatigue lives were shorter at 560 C as compared to 260 C due to changes in mode of matrix failure. On a total strain basis, the fatigue life of the composite at 560 C was the same as the life of unreinforced copper, indicating that the presence of the fibers did not degrade the fatigue resistance of the copper matrix in this composite system. Comparison of strain-controlled fatigue data to previously-generated load-controlled data revealed that the strain-controlled fatigue lives were longer because of mean strain and mean stress effects.

  13. Crack path for run-out specimens in fatigue tests: is it belonging to high- or very-high-cycle fatigue regime?

    Directory of Open Access Journals (Sweden)

    A. Shanyavskiy

    2015-10-01

    Full Text Available Fatigue tests run-out specimens up to 106 – 5x107 load cycles are used to determine the stress level named “fatigue limit”. Nevertheless, it is not clear what kind of fatigue cracking takes or will take place in these specimens. To discuss this problem, fatigue tests of titanium alloy VT3-1 specimens have been performed under tension with different values of R-ratio and under rotating-bending after various thermo-mechanical treatments (tempering, surface hardening and their combinations. Well-known S-N curves in High-Cycle- Fatigue regime have been plotted with run-out specimens usually used for “fatigue limit” determination. Then, after fatigue tests, run-out specimens have been tensed up to their failure, and fracture surface analyses have been performed for all tested specimens. It is found that run-out specimens in all combinations of treatments, for different R-ratio, have fracture surfaces for crack path in Very-High-Cycle-Fatigue regime. Based on this result, all S-N curves have been reconstructed in duplex curves for High- and Very-High-Cycle-Fatigue regime without using knowledge about “fatigue limit”. Detailed fracture surfaces analyses have been developed, and crack paths have been compared for various combinations of materials and surface states.

  14. Effect of interstitial content on high- temperature fatigue crack propagation and low- cycle fatigue of alloy 720

    Science.gov (United States)

    Bashir, S.; Thomas, M. C.

    1993-08-01

    Alloy 720 is a high-strength cast and wrought turbine disc alloy currently in use for temperatures up to about 650 °C in Allison’s T800, T406, GMA 2100, and GMA 3007 engines. In the original composition in-tended for use as turbine blades, large carbide and boride stringers formed and acted as preferred crack initiators. Stringering was attributed to relatively higher boron and carbon levels. These interstitials are known to affect creep and ductility of superalloys, but the effects on low-cycle fatigue and fatigue crack propagation have not been studied. Recent emphasis on the total life approach in the design of turbine discs necessitates better understanding of the interactive fatigue crack propagation and low-cycle fatigue behavior at high temperatures. The objective of this study was to improve the damage tolerance of Alloy 720 by systematically modifying boron and carbon levels in the master melt, without altering the low-cy-cle fatigue and strength characteristics of the original composition. Improvement in strain-controlled low-cycle fatigue life was achieved by fragmenting the continuous stringers via composition modifica-tion. The fatigue crack propagation rate was reduced by a concurrent reduction of both carbon and bo-ron levels to optimally low levels at which the frequency of brittle second phases was minimal. The changes in composition have been incorporated for production disc forgings.

  15. 中医五行音乐对恶性肿瘤化疗患者癌因性疲乏的影响%Effect of traditional Chinese medicine five elements music on cancer-related fatigue of chemotherapy patients

    Institute of Scientific and Technical Information of China (English)

    黄云娜; 杨曦; 杨秋敏

    2012-01-01

    Objective To study the effect of traditional Chinese medicine (TCM) five elements music on cancer-related fatigue CRF of chemotherapy patients.Methods 80 patients were randomly divided into the experimental group and the control group equally.The experimental group was given the TCM five elements music intervention on the basis of routine care at the start of chemotherapy for 60 min,once a day for three cycles,each cycle and chemotherapy cycle were synchronic.The control group was given routine care with emphasis on psychological care.The two groups were given the CRF assessment of Brief Fatigue Inventory developed by the pain research team of the U.S.Adorson Cancer Center before and after the treatment,and the quality of life of patients was evaluated by Quality of Life Questionnaire (EORTC-QLQ-C30) by the European Cancer Treatment and Research Organization.Results CRF levels of the experimental group were markedly reduced after the intervention of TCM five elements music,among which slight fatigue accounted for 37.5%,moderate fatigue accounted for 10% and serious fatigue accounted for 2.5%.There was significant difference between the two groups ( U =6.062 3,P < 0.0 1 ).The proportion of moderate and serious fatigue was 12.5% in the experimental group and 40% in the control group after treatment,and there was significant difference between the two groups (U=3.282 8,P<0.01 ).The total score of quality of life was (43.12±6.21) in the experimental group and (52.30 ± 7.28 ) in the control group after treatment.The difference was statistically significant (t =4.683 0,P<0.05).Conclusions Application of TCM Five Elements music intervention on chemotherapy patients can eliminate or alleviate CRF and improve the quality of life of patients.%目的 探讨中医五行音乐对恶性肿瘤化疗患者癌因性疲乏和生活质量的影响.方法 将80例恶性肿瘤化疗患者随机分为试验组40例和对照组40例.试验组在常规治疗护理的基

  16. High cycle fatigue properties of CLAM steel at 723 K and 823 K

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Yanyun; Zhai, Xiangwei; Liu, Shaojun, E-mail: shaojun.liu@fds.org.cn; Li, Chunjing; Huang, Qunying

    2015-11-15

    Highlights: • High cycle fatigue properties of CLAM steel were investigated at 723 K and 823 K. • The condition fatigue limit at N = 10{sup 7} were 275 MPa and 235 MPa at 723 K and 823 K. • Fatigue strength decreased when stress and temperature increased at 723 K and 823 K. • Dislocation density decrease and subgrain coarsening during the test process were the possible reasons for fatigue limit decrease. - Abstract: This paper highlights the results of a study on the high cycle fatigue strength and fracture mechanism of China Low Activation Martensitic (CLAM) steel. The high cycle fatigue test results showed that the fatigue strength of CLAM steel decreased with the temperature, and the condition fatigue strengths (N = 10{sup 7}) were 275 MPa and 235 MPa at 723 K and 823 K, respectively. The fractograph results indicated that the fractures were mainly initiated from the surface of the specimen.

  17. The effect of histidine on mental fatigue and cognitive performance in subjects with high fatigue and sleep disruption scores.

    Science.gov (United States)

    Sasahara, Ikuko; Fujimura, Naoko; Nozawa, Yoshizu; Furuhata, Yasufumi; Sato, Hitoshi

    2015-08-01

    Our previous study reported that a dried bonito broth known in Japan as 'dashi' improved or ameliorated mood states, including fatigue, during the daily lives of human subjects. Histidine is an amino acid that is present in dried bonito broth, and we sought to evaluate whether histidine would affect feelings of fatigue in humans. We investigated the effects of histidine intake on the feeling of fatigue, mood states and mental task performance by performing a placebo-controlled, double-blind crossover trial. Twenty subjects with high fatigue and sleep disruption scores were asked to ingest histidine or a placebo every day for two weeks. The subjects' mood states were evaluated using the Profile of Mood States (POMS) scale and a visual analog scale (VAS) for eight feelings (fatigue, depression, carelessness, drowsiness, clear thinking, motivation, attentiveness and concentration). We also measured subjects' cognitive performance using the CogHealth test battery. The fatigue T-scores on the POMS test decreased significantly following histidine ingestion compared to placebo ingestion (phistidine ingestion, the reaction time for the working memory task in the CogHealth test battery was significantly shorten compared to placebo ingestion. The VAS scores for clear thinking and for attentiveness were increased significantly following histidine ingestion compared to placebo ingestion (phistidine may ameliorate feelings of fatigue, increase performance during working memory tasks, and improve the clear thinking and attentiveness.

  18. Fatigue behaviour of high strength AA 7012 aluminium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Di Russo, E.; Ragazzini, R.; Buratti, M.; Ferrarin, C. (Aluminia-ISML, Novara (Italy) Caproni Vizzola costruzioni aeronautiche, Somma Lombarda (Italy))

    1990-02-01

    The alloy 7012 (Al, 6.2% Zn, 2% Mg, 1% Cn, 0.13% Mn, 0.14% Zn, 0.04% Ti) belongs to the 7XXX family of high mechanical resistance alloys containing Zr as the principal additive. Produced in the form of extrusions, sheets and forgings, the alloy finds application in the defense, transportation and power industry fields. This paper presents the results of experimental fatigue tests (10/sup 7/ cycles) on 7020 in the T6 and T73 temper conditions and draws comparisons with corresponding test results on 7075 and 2024 type alloys. A comparative analysis of S-N curves obtained from plane bending and axial fatigue tests on smooth and notched specimens evidences the superior performance of 7020 in terms of higher strength and corrosion cracking resistance.

  19. High Power RF Induced Thermal Fatigue in the High Gradient CLIC Accelerating Structures

    CERN Document Server

    Arnau-Izquierdo, G; Heikkinen, S; Neupert, N; Wuensch, W

    2007-01-01

    The need for high accelerating gradients for the CLIC (Compact Linear Collider) imposes considerable constraints on the materials of the accelerating structures. The surfaces exposed to high pulsed RF (Radio Frequency) currents are subjected to cyclic thermal stresses possibly resulting in surface break up by fatigue. Various high strength alloys from the group of high conductivity copper alloys have been selected and have been tested in different states, with different surface treatments and in different stress ratios. Low to medium cycle fatigue data (up to 108 cycles) of fully compressive surface thermal stresses has been collected by means of a pulsed laser surface heating apparatus. The surface damage has been characterized by SEM observations and roughness measurements. High cycle fatigue data, up to 7x1010 cycles, of varying stress ratio has been collected in high frequency bulk fatigue tests using an ultrasonic apparatus. Up-to-date results from these experiments are presented.

  20. Interaction of fatigue and creep of GH33 under multi-axial stress at high temperature

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Low-cycle fatigue experiments of tension-compression, torsion and tension-torsion with holding time were performed.The interaction law of creep and fatigue under multiaxial stress at high temperature was investigated, and the micro-mechanism ofequilibrium diagrams was analyzed. A united equation of fatigue life under multiaxial stress was proposed.

  1. Al-Li alloy AA2198's very high cycle fatigue crack initiation mechanism and its fatigue thermal effect

    Science.gov (United States)

    Xu, Luopeng; Cao, Xiaojian; Chen, Yu; Wang, Qingyuan

    2015-10-01

    AA2198 alloy is one of the third generation Al-Li alloys which have low density, high elastic modulus, high specific strength and specific stiffness. Compared With the previous two generation Al-Li alloys, the third generation alloys have much improved in alloys strength, corrosion resistance and weldable characteristic. For these advantages, the third generation Al-Li alloys are used as aircraft structures, such as C919 aviation airplane manufactured by China and Russia next generation aviation airplane--MS-21. As we know, the aircraft structures are usually subjected to more than 108 cycles fatigue life during 20-30 years of service, however, there is few reported paper about the third generation Al-Li alloys' very high cycle fatigue(VHCF) which is more than 108 cycles fatigue. The VHCF experiment of AA2198 have been carried out. The two different initiation mechanisms of fatigue fracture have been found in VHCF. The cracks can initiate from the interior of the testing material with lower stress amplitude and more than 108 cycles fatigue life, or from the surface or subsurface of material which is the dominant reason of fatigue failures. During the experiment, the infrared technology is used to monitor the VHCF thermal effect. With the increase of the stress, the temperature of sample is also rising up, increasing about 15 °C for every 10Mpa. The theoretical thermal analysis is also carried out.

  2. The effect of high-frequencies loading on the fatigue cracking of nodular cast iron

    Directory of Open Access Journals (Sweden)

    R. Ulewicz

    2017-01-01

    Full Text Available The article presents the results of fatigue tests using high-frequency loading of nodular cast iron. Nodular cast iron GJS-500-7, GJS-600-3 and cast iron ADI with a tensile strength of Rm = 1 125 MPa were used for the tests. The fatigue tests were conducted on a resonance testing machine. For the cast iron grades under investigation, fatigue characteristics in high and ultra-high-cycle regions were experimentally determined. After the completion of the tests, the fractographic analysis of fatigue fractures was made with the aim of determining the fatigue crack initiation location and the fracture mechanism.

  3. Fatigue test of carbon epoxy composite high pressure hydrogen storage vessel under hydrogen environment

    Institute of Scientific and Technical Information of China (English)

    Chuan-xiang ZHENG; Liang WANG; Rong LI; Zong-xin WEI; Wei-wei ZHOU

    2013-01-01

    A significant temperature raise within hydrogen vehicle cylinder during the fast filling process will be observed,while the strength and fatigue life of the cylinder will dramatically decrease at high temperature.In order to evaluate the strength and fatigue of composite hydrogen storage vessel,a 70-MPa fatigue test system using hydrogen medium was set up.Experimental study on the fatigue of composite hydrogen storage vessels under real hydrogen environment was performed.The experimental results show that the ultimate strength and fatigue life both decreased obviously compared with the values under hydraulic fatigue test.Furthermore,fatigue property,failure behavior,and safe hydrogen charging/discharging working mode of onboard hydrogen storage vessels were obtained through the fatigue tests.

  4. Fatigue in Welded High-Strength Steel Plate Elements under Stochastic Loading

    DEFF Research Database (Denmark)

    Agerskov, Henning; Petersen, R.I.; Martinez, L. Lopez

    1999-01-01

    The present project is a part of an investigation on fatigue in offshore structures in high-strength steel. The fatigue life of plate elements with welded attachments is studied. The material used has a yield stress of ~ 810-840 MPa, and high weldability and toughness properties. Fatigue test...... series with constant amplitude loading and with various types of stochastic loading have been carried through on test specimens in high-strength steel, and - for a comparison - on test specimens in conventional offshore structural steel with a yield stress of ~ 400-410 MPa.A comparison between constant...... amplitude and variable amplitude fatigue test results shows shorter fatigue lives in variable amplitude loading than should be expected from the linear fatigue damage accumulation formula. Furthermore, in general longer fatigue lives were obtained for the test specimens in high-strength steel than those...

  5. MYOELECTRIC ALTERATIONS AFTER VOLUNTARY INDUCED HIGH - AND LOW - FREQUENCY FATIGUE

    Directory of Open Access Journals (Sweden)

    Vojko Strojnik

    2008-06-01

    Full Text Available The aim of the study was to find whether voluntary induced high- and low-frequency peripheral fatigue exhibit specific alteration in surface EMG signal (SEMG during evoked and maximum voluntary contractions. Ten male students of physical education performed 60 s long stretch-shortening cycle (SSC exercise with maximal intensity and 30 s long concentric (CON exercise with maximal intensity. To verify voluntary induced peripheral fatigue, knee torques during low- (T20 and high-frequency electrical stimulation (T100 of relaxed vastus lateralis muscle (VL were obtained. Contractile properties of the VL were measured with passive twitch and maximal voluntary knee extension test (MVC. Changes in M-waves and SEMG during MVC test were used to evaluate the differences in myoelectrical signals. T100/T20 ratio decreased by 10.9 ± 8.4 % (p < 0.01 after the SSC exercise and increased by 35.9 ± 17.5 % (p < 0.001 after the CON exercise. Significant SEMG changes were observed only after the CON exercise where peak to peak time of the M-waves increased by 9.2 ± 13.3 % (p < 0.06, SEMG amplitude during MVC increased by 32.9 ± 21.6 % (p < 0.001 and SEMG power spectrum median frequency decreased by 11.0 ± 10.5 % (p < 0.05. It is concluded that high frequency fatigue wasn't reflected in SEMG, however the SEMG changes after the CON seemed to reflect metabolic changes due to acidosis

  6. Low cycle fatigue behavior of high strength gun steels

    Institute of Scientific and Technical Information of China (English)

    Maoqiu Wang; Han Dong; Qi Wang; Changgang Fan

    2004-01-01

    The low cycle fatigue (LCF) behavior of two high strength steels, with nominal chemical compositions (mass fraction, %)of 0.40C-1.5Cr-3Ni-0.4Mo-0.2V (PCrNi3MoV) and 0.25C-3Cr-3Mo-0.8Ni-0.1Nb (25Cr3Mo3NiNb), was investigated by using the smooth bar specimens subjected to strained-controlled push-pull loading. It is found that both steels show cyclic softening, but 25Cr3Mo3NiNb steel has a lower tendency to cyclic softening. 25Cr3Mo3NiNb steel has higher fatigue ductility, and its transition fatigue life is almost three times that of PCrNi3MoV. 25Cr3Mo3NiNb steel also shows higher LCF life either at a given total strain amplitude above 0.5% or at any given plastic strain amplitude, despite its lower monotonic tensile strength than that of PCrNi3MoV.It also means that 25Cr3Mo3NiNb steel can endure higher total strain amplitude and plastic strain amplitude at a given number of reversals to failure within 104. 25Cr3Mo3NiNb steel is expected to be a good gun steel with high LCF properties because only several thousand firings are required for gun barrel in most cases.

  7. 乳腺癌化疗患者癌性疲乏、应对方式与生活质量的相关性%Relationship among Cancer-Related Fatigue,Coping Style and Quality of Life in Patients of Breast Cancer with Chemotherapy

    Institute of Scientific and Technical Information of China (English)

    王梅芳; 李小妹

    2009-01-01

    Objective:To explore the relationship among the cancer-related fatigue,coping styles and quality of life in breast cancer patients with chemotherapy.Methods:A total 120 female breast cancer patients were selected as the subjects.The instrument used for data collection was a questionnaire that was composed of four parts:the demographic data form,the Revised Piper Fatigue Scale (PFS),Jalowiec Coping Scale (JCS),Quality of Life Questionnaire-Core 30 (QLQ-C30),and Quality of Life Questionnaire-Breast 23 (QLQ-BR23).The statistical software SPSS was used for data analysis.Cancer-related fatigue,coping styles,quality of life and their related factors were determined by nonparametric tests.Spearman correlation coefficient was used to investigate the relationship among cancer-related fatigue,coping styles and quality of life in breast cancer patients with chemotherapy.Results:There was a significant negative moderate correlation between cancer-related fatigue and the quality of life (r=-0.24,P<0.01),and negative correlation between cancer-related fatigue and the total health status (r=-0.39,P<0.01).The positive coping styles including optimistic and confronting were negatively correlated with cancer-related fatigue (r=-0.25,-0.18,Ps<0.05),and were positively related to the functional domain of quality of life(r=0.35,0.21, Ps<0.05).The positive coping styles including emotive,fatalistic,and palliative were positively correlated with cancer-related fatigue (r=0.25,0.18,and 0.28, Ps<0.05),and were negatively correlated with the functional domain of quality of life (r=-0.40,-0.32,Ps<0.05),and emotive and fatalistic were positively related to the symptomatic domain of quality of life(r=0.40,0.28,Ps<0.05).Conclusion:There exists a certain degree of correlation among cancer-related fatigue,coping styles and quality of life in breast cancer patients with chemotherapy,which may guide the clinical care.%目的:探讨乳腺癌化疗患者癌性疲乏、应对

  8. Influence of self-management on cancer-related fatigue symptoms and quality of life of patients with digestive malignancies%自我管理对消化系统恶性肿瘤病人癌因性疲乏症状及其生命质量的影响

    Institute of Scientific and Technical Information of China (English)

    张淼; 王维利; 李成; 赵江

    2013-01-01

    Objective:To probe into the influence of self-management on cancer-related fatigue symptoms and quality of life of patients with digestive malignancies.Methods:By using convenient sampling,a total of 62 patients met the inclusion criteria were randomly divided into intervention group and control group,31 cases in each.The control group patients were given conventional nursing care,intervention group patients were given symptoms interventions of self-management based on conventional nursing.The cancer fatigue scale (CFS) for measurements was carried out for patients on 1st day after admitting to hospital,postoperative 7th day and a day before discharge,functional assessment of cancer therapy scale (FACT-G)was used for measurements for patients on 1st day after admitting to hospital and a day before discharge,so as to evaluate the cancer-related fatigue and quality of life of two groups of patients before and after the intervention.Results:The cancer related fatigue levels at different times in both groups had change trends with time changes,the cancer related fatigue in intervention group decreased more faster than that in control group.Total score of quality of life and all dimension scores of patients in intervention group were higher than that of control group (P<0.01).Conclusion:Symptom management model based on self-management can effectively alleviate perioperative cancer related fatigue symptoms in patients with digestive malignancies and improve their quality of life.%[目的]探讨自我管理对消化系统恶性肿瘤病人围术期癌因性疲乏症状及其生命质量的影响.[方法]采用方便抽样法,将符合纳入标准的62例病人随机分为干预组和对照组各31例.对照组给予常规护理,干预组在常规护理基础上进行自我管理的症状干预.在病人入院第1天、术后第7天及出院前1d采用癌症疲乏量表(CFS)进行测量,在病人入院第1天和出院前1d采用癌症治疗功能

  9. HIGH CYCLE FATIGUE PROPERTIES OF NICKEL-BASE ALLOY 718

    Institute of Scientific and Technical Information of China (English)

    K.Kobayashi; K.Yamaguchi; M.Hayakawa; M.Kimura

    2004-01-01

    The fatigue properties of nickel-base Alloy 718 with fine- and grain-coarse grains were investigated. In the fine-grain alloy, the fatigue strength normalized by the tensile strengtn was 0.51 at 107 cycles. In contrast, the fatigue strength of the coarse-grain alloy was 0.32 at the same cycles, although the fatigue strengths in the range from 103to 105 cycles are the same for both alloys. The fracture appearances fatigued at around 106 cycles showed internal fractures originating from the flat facets of austenite grains for both alloys. The difference in fatigue strength at 107 cycles between the fine- and coarse-grain alloys could be explained in terms of the sizes of the facets from which the fractures originated.

  10. Probabilistic Material Strength Degradation Model for Inconel 718 Components Subjected to High Temperature, High-Cycle and Low-Cycle Mechanical Fatigue, Creep and Thermal Fatigue Effects

    Science.gov (United States)

    Bast, Callie C.; Boyce, Lola

    1995-01-01

    The development of methodology for a probabilistic material strength degradation is described. The probabilistic model, in the form of a postulated randomized multifactor equation, provides for quantification of uncertainty in the lifetime material strength of aerospace propulsion system components subjected to a number of diverse random effects. This model is embodied in the computer program entitled PROMISS, which can include up to eighteen different effects. Presently, the model includes five effects that typically reduce lifetime strength: high temperature, high-cycle mechanical fatigue, low-cycle mechanical fatigue, creep and thermal fatigue. Results, in the form of cumulative distribution functions, illustrated the sensitivity of lifetime strength to any current value of an effect. In addition, verification studies comparing predictions of high-cycle mechanical fatigue and high temperature effects with experiments are presented. Results from this limited verification study strongly supported that material degradation can be represented by randomized multifactor interaction models.

  11. Room temperature creep-fatigue response of selected copper alloys for high heat flux applications

    DEFF Research Database (Denmark)

    Li, M.; Singh, B.N.; Stubbins, J.F.

    2004-01-01

    Two copper alloys, dispersion-strengthened CuAl25 and precipitation-hardened CuCrZr, were examined under fatigue and fatigue with hold time loading conditions. Tests were carried out at room temperature and hold times were imposed at maximum tensile and maximum compressive strains. It was found...... times. The influence of hold times on fatigue life in the low cycle fatigue, short life regime (i.e., at high strain amplitudes) was minimal. When hold time effects were observed, fatigue lives were reduced with hold times as short as two seconds. Appreciable stress relaxation was observed during...... the hold period at all applied strain levels in both tension and compression. In all cases, stresses relaxed quickly within the first few seconds of the hold period and much more gradually thereafter. The CuAl25 alloy showed a larger effect of hold time on reduction of high cycle fatigue life than did...

  12. High-cycle Fatigue Properties of Alloy718 Base Metal and Electron Beam Welded Joint

    Science.gov (United States)

    Ono, Yoshinori; Yuri, Tetsumi; Nagashima, Nobuo; Sumiyoshi, Hideshi; Ogata, Toshio; Nagao, Naoki

    High-cycle fatigue properties of Alloy 718 plate and its electron beam (EB) welded joint were investigated at 293 K and 77 K under uniaxial loading. At 293 K, the high-cycle fatigue strength of the EB welded joint with the post heat treatment exhibited somewhat lower values than that of the base metal. The fatigue strengths of both samples basically increased at 77 K. However, in longer life region, the EB welded joint fractured from a blow hole formed in the welded zone, resulting in almost the same fatigue strength at 107 cycles as that at 293 K.

  13. Thermally Induced Ultra High Cycle Fatigue of Copper Alloys of the High Gradient Accelerating Structures

    CERN Document Server

    Heikkinen, Samuli; Wuensch, Walter

    2010-01-01

    In order to keep the overall length of the compact linear collider (CLIC), currently being studied at the European Organization for Nuclear Research (CERN), within reasonable limits, i.e. less than 50 km, an accelerating gradient above 100 MV/m is required. This imposes considerable demands on the materials of the accelerating structures. The internal surfaces of these core components of a linear accelerator are exposed to pulsed radio frequency (RF) currents resulting in cyclic thermal stresses expected to cause surface damage by fatigue. The designed lifetime of CLIC is 20 years, which results in a number of thermal stress cycles of the order of 2.33•1010. Since no fatigue data existed in the literature for CLIC parameter space, a set of three complementary experiments were initiated: ultra high cycle mechanical fatigue by ultrasound, low cycle fatigue by pulsed laser irradiation and low cycle thermal fatigue by high power microwaves, each test representing a subset of the original problem. High conductiv...

  14. Experimental study of crack initiation and propagation in high- and gigacycle fatigue in titanium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Bannikov, Mikhail, E-mail: mbannikov@icmm.ru, E-mail: oborin@icmm.ru, E-mail: naimark@icmm.ru; Oborin, Vladimir, E-mail: mbannikov@icmm.ru, E-mail: oborin@icmm.ru, E-mail: naimark@icmm.ru; Naimark, Oleg, E-mail: mbannikov@icmm.ru, E-mail: oborin@icmm.ru, E-mail: naimark@icmm.ru [Institute of Continuous Media Mechanics UrB RAS, Perm, 614013 (Russian Federation)

    2014-11-14

    Fatigue (high- and gigacycle) crack initiation and its propagation in titanium alloys with coarse and fine grain structure are studied by fractography analysis of fracture surface. Fractured specimens were analyzed by interferometer microscope and SEM to improve methods of monitoring of damage accumulation during fatigue test and to verify the models for fatigue crack kinetics. Fatigue strength was estimated for high cycle fatigue regime using the Luong method [1] by “in-situ” infrared scanning of the sample surface for the step-wise loading history for different grain size metals. Fine grain alloys demonstrated higher fatigue resistance for both high cycle fatigue and gigacycle fatigue regimes. Fracture surface analysis for plane and cylindrical samples was carried out using optical and electronic microscopy method. High resolution profilometry (interferometer-profiler New View 5010) data of fracture surface roughness allowed us to estimate scale invariance (the Hurst exponent) and to establish the existence of two characteristic areas of damage localization (different values of the Hurst exponent). Area 1 with diameter ∼300 μm has the pronounced roughness and is associated with damage localization hotspot. Area 2 shows less amplitude roughness, occupies the rest fracture surface and considered as the trace of the fatigue crack path corresponding to the Paris kinetics.

  15. RESTORE: an exploratory trial of an online intervention to enhance self-efficacy to manage problems associated with cancer-related fatigue following primary cancer treatment: study protocol for a randomized controlled trial

    OpenAIRE

    Grimmett, Chloe; Armes, Jo; Breckons, Matthew; Calman, Lynn; Corner, Jessica; Fenlon, Deborah; Hulme, Claire; May, Christine M.; May, Carl; Ream, Emma; Richardson, Alison; Peter W.F Smith; Yardley, Lucy; Foster, Claire

    2013-01-01

    Background: There are over 25 million people worldwide living with or beyond cancer and this number is increasing. Cancer survivors face a range of problems following primary treatment. One of the most frequently reported and distressing symptoms experienced by cancer survivors is fatigue. There is growing support for survivors who are experiencing problems after cancer treatment to engage in supported self-management. To date there is some evidence of effective interventions to manage fatigu...

  16. Mechanical Fatigue Testing of High Burnup Fuel for Transportation Applications

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jy-An John [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Wang, Hong [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2015-05-01

    This report describes testing designed to determine the ability of high burnup (HBU) (>45 GWd/MTU) spent fuel to maintain its integrity under normal conditions of transportation. An innovative system, Cyclic Integrated Reversible-bending Fatigue Tester (CIRFT), has been developed at Oak Ridge National Laboratory (ORNL) to test and evaluate the mechanical behavior of spent nuclear fuel (SNF) under conditions relevant to storage and transportation. The CIRFT system is composed of a U-frame equipped with load cells for imposing the pure bending loads on the SNF rod test specimen and measuring the in-situ curvature of the fuel rod during bending using a set up with three linear variable differential transformers (LVDTs).

  17. High temperature fatigue of metal matrix composite for automotive applications

    Energy Technology Data Exchange (ETDEWEB)

    Marie-Louise, A.; Koster, A.; Remy, L. [Centre des Materiaux, PM. Fourt, Ecole Nationale Superieure des Mines de Paris, UMR CNRS 763, Evry (France); Bourgeois, M.; Martin-Borret, S. [PSA, Peugeot Citroeen, Direction de la Recherche et de l' Innovation Automobile, Velizy-Villacoublay (France)

    2004-07-01

    The high temperature low cycle fatigue (LCF) of metal-matrix composite (A356 with alumina reinforcement) was investigated. LCF tests interrupted and conducted up to failure were performed. Firstly, the effect of process defects and volume fraction of alumina was investigated for this composite. Then, damage accumulation was reported: an interrupted test procedure was used with a plastic replication technique. According to crack growth, the end of the LCF test is associated with a critical crack length equal to about 2 mm. Furthermore, an original crack growth LCF test was made using a specimen with three through notches at different locations. The effect of notch location was estimated. TOMKINS' model has finally been modified to predict the LCF crack growth and the life of smooth specimens. (orig.)

  18. Review of 20 years research in fatigue of high pressure loaded components

    Energy Technology Data Exchange (ETDEWEB)

    Thumser, Rayk [Bauhaus Univ. Weimar (Germany). Materialforschungs- und -pruefanstalt; Scheibe, Wolfgang

    2011-07-01

    This paper gives an overview of the research in fatigue of high pressure loaded components. In the last 20 years the main research was carried out in Germany. This research was mainly driven by the fatigue requirements for high pressure loaded Diesel engine injection parts as common rails, injectors and pipes. (orig.)

  19. Effects of structure and defect on fatigue limit in high strength ductile irons

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jin Hak; Kim, Min Gun [Kangwon National Univ., Chunchon (Korea, Republic of)

    2000-05-01

    In this paper, the influence of several factors such as hardness, internal defect and non-propagating crack on fatigue limits was investigated with three kinds of ductile iron specimens. From the experimental results the fatigue limits were examined in relation with hardness and tensile strength in case of high strength specimens under austempering treatment; in consequence the marked improvement of fatigue limits were not showed. The maximum defect size was an important factor to predict and to evaluate the fatigue limits of ductile irons. And, the quantitative relationship between the fatigue limits({sigma}{sub {omega}}) and the maximum defect size({radical}area{sub max}) was expressed as {sigma}{sub {omega}}{sup n} {center_dot} {radical}area{sub max}=C{sub 2}. Also, it was possible to explain the difference for the fatigue limits in three ductile irons by introduction of the non-propagating crack rates.

  20. Influence of neodymium on high cycle fatigue behavior of die cast AZ91D magnesium alloy

    Institute of Scientific and Technical Information of China (English)

    杨友; 李雪松

    2010-01-01

    High cycle fatigue behavior of die cast AZ91D magnesium alloy with different Nd contents was investigated.Axial mechanical fatigue tests were conducted at the stress ratio R=0.1 and the fatigue strength was evaluated using up-to-down load method on specimens of AZ91D with different Nd contents.The results showed that the grain of AZ91D alloy was refined,the size and amount of β-Mg17Al12 phase decreased and distributed uniformly with increasing Nd content.At the number of cycles to failure,Nf=107,the fatigue...

  1. High-cycle fatigue behavior of ultrafine-grained austenitic stainless and TWIP steels

    Energy Technology Data Exchange (ETDEWEB)

    Hamada, A.S. [Materials Engineering Laboratory (4KOMT), Box 4200, University of Oulu, 90014 Oulu (Finland); Metallurgical and Materials Engineering Department, Faculty of Petroleum and Mining Engineering, Suez Canal University, Box 43721, Suez (Egypt); Karjalainen, L.P., E-mail: pentti.karjalainen@oulu.fi [Materials Engineering Laboratory (4KOMT), Box 4200, University of Oulu, 90014 Oulu (Finland)

    2010-08-20

    High-cycle fatigue behavior of ultrafine-grained (UFG) 17Cr-7Ni Type 301LN austenitic stainless and high-Mn Fe-22Mn-0.6C TWIP steels were investigated in a reversed plane bending fatigue and compared to the behavior of steels with conventional coarse grain (CG) size. Optical, scanning and transmission electron microscopy were used to examine fatigue damage mechanisms. Testing showed that the fatigue limits leading to fatigue life beyond 4 x 10{sup 6} cycles were about 630 MPa for 301LN while being 560 MPa for TWIP steel, and being 0.59 and 0.5 of the tensile strength respectively. The CG counterparts were measured to have the fatigue limits of 350 and 400 MPa. The primary damage caused by fatigue took place by grain boundary cracking in UFG 301LN, while slip band cracking occurred in CG 301LN. However, in the case of TWIP steel, the fatigue damage mechanism is similar in spite of the grain size. In the course of cycling neither the formation of a martensite structure nor mechanical twinning occurs, but intense slip bands are created with extrusions and intrusions. Fatigue crack initiates preferentially on grain and twin boundaries, and especially in the intersection sites of slip bands and boundaries.

  2. Multiaxial fatigue behavior of conventional and highly crosslinked UHMWPE during cyclic small punch testing.

    Science.gov (United States)

    Villarraga, M L; Kurtz, S M; Herr, M P; Edidin, A A

    2003-08-01

    Previous observations of reduced uniaxial elongation, fracture resistance, and crack propagation resistance of highly crosslinked ultrahigh molecular weight polyethylene (UHMWPE) have contributed to concern that the technology may not be appropriate for systems undergoing cyclic fatigue loading. Using a "total life" approach, we examined the influence of radiation crosslinking on the fatigue response of UHMWPE under cyclic loading via the small punch test. Our goal in this study was to evaluate the suitability of the small punch test for conducting miniature-specimen, cyclic loading, and fatigue experiments of conventional and highly crosslinked UHMWPE. We subjected four types of conventional and highly crosslinked UHMWPE to cyclic loading at 200 N/s and at body temperature in a small punch test apparatus. After failure, the fracture surfaces were characterized with the use of field emission scanning electron microscopy to evaluate the fatigue mechanisms. Cyclic small punch testing under load control was found to be an effective and repeatable method for relative assessment of the fatigue resistance of conventional and highly crosslinked UHMWPE specimens under multiaxial loading conditions. For each of the four conventional and highly crosslinked UHMWPE materials evaluated in this study, fatigue failures were consistently produced according to a power law relationship in the low cycle regimen, corresponding to failures below 10000 cycles. The fatigue failures were all found to be consistent with a single source of initiation and propagation to failure. Our long-term goal in this research is to develop miniature-specimen fatigue testing techniques for characterization of retrieved UHMWPE inserts.

  3. Ultra-high cycle fatigue behavior of high strength steel with carbide-free bainite/martensite complex microstructure

    Institute of Scientific and Technical Information of China (English)

    Xue-xia Xu; Yang Yu; Wen-long Cui; Bing-zhe Bai; Jia-lin Gu

    2009-01-01

    The ultra-high cycle fatigue behavior of a novel high strength steel with carbide-free bainite/martensite (CFB/M) complex microstructure was studied. The ultra-high cycle fatigue properties were measured by ultrasonic fatigue testing equipment at a fre-quency of 20 kHz. It is found that there is no horizontal part in the S-N curve and fatigue fracture occurs when the life of specimens exceeds 107 cycles. In addition, the origination of fatigue cracks tends to transfer from the surface to interior of specimens as the fa-tigue cycle exceeds 107 , and the fatigue crack originations of many specimens are not induced by inclusions, but by some kind of "soft structure". It is shown that the studied high strength steel performs good ultra-high cycle fatigue properties. The ultra-high fa-tigue mechanism was discussed and it is suggested that specific CFB/M complex microstrueture of the studied steel contributes to itssuperior properties.

  4. A New Perspective on Fatigue Performance of Advanced High- Strength Steels (AHSS) GMAW Joints

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Zhili [ORNL; Chiang, Dr. John [Ford Motor Company; Kuo, Dr. Min [MIttal Steel; Jiang, Cindy [AET Integration, Inc; Sang, Yan [AET Integration, Inc

    2008-01-01

    Weld fatigue performance is a critical aspect for application of advanced high-strength steels (AHSS) in automotive body structures. A comparative study has been conducted to evaluate the fatigue life of AHSS welds. The material studied included seven AHSS of various strength levels - DP 600, DP 780, DP 980, M130, M220, solution annealed boron and fully hardened boron steels. Two conventional steels, HSLA 590 and DR 210, were also included for baseline comparison. Lap fillet welds were made on 2-mm nominal thick sheets by the gas metal arc welding process (GMAW). Fatigue test was conducted under a number of stress levels to obtain the S/N curves of the weld joints. It was found that, unlike in the static and impact loading conditions, the fatigue performance of AHSS is not influenced by the HAZ softening in AHSS. There are appreciable differences in the fatigue lives among different AHSS. Changes in weld parameters can influence the fatigue life of the weld joints, particularly of these of higher strength AHSS. A model is developed to predict the fatigue performance of AHSS welds. The validity of the model is benchmarked with the experimental results. This model is capable to capture the effects of weld geometry and weld microstructure and strength on the fatigue performance experimentally observed. The theoretical basis and application of the newly developed fatigue modeling methodology will be discussed.

  5. Fatigue properties of high-strength materials used in cold-forging tools

    DEFF Research Database (Denmark)

    Brøndsted, P.; Skov-Hansen, P.

    1998-01-01

    In the present work classical analytical models are used to describe the static stress–strain curves, low-cycle fatigue properties and fatigue crack growth behaviour of high-strength materials for use in tools for metal-forming processes such as cold forging and extrusion. The paper describes...

  6. Cancer Caregiver Fatigue: A High Level of Symptom Burden

    OpenAIRE

    2013-01-01

    Fatigue is the problematic symptom identified by cancer patients. However, fatigue has not been widely examined for caregivers of cancer patients. In this project, 131 caregivers of patients diagnosed with advanced stage cancer and actively receiving radiotherapy reported experiencing the most difficulties with fatigue (mean 46.9; on a 0 to 100 scale, with a 10-point difference having clinical meaning) at baseline and at a six-month follow-up (mean 48.3). This is in sharp contrast to other do...

  7. Fatigue failure of hydrogen embrittled high strength steels

    Science.gov (United States)

    Kim, Y. G.; Aleszka, J.

    1975-01-01

    Results of an experimental investigation are presented concerning the fracture behavior of cathodically charged, quenched and tempered martensitic steels under cyclic load conditions. Introduction of H2 by cathodic charging reduced fatigue life by as much as 60%. It is proposed that subsurface transverse fatigue cracks nucleate simultaneously at multiple sites, such as at microcracks, voids, or inclusions. Fatigue crack growth then occurs on planes perpendicular to the major applied stress axis in the presence of the critical combination of applied external stress and hydrogen.

  8. Fatigue during high-intensity intermittent exercise: application to bodybuilding.

    Science.gov (United States)

    Lambert, Charles P; Flynn, Michael G

    2002-01-01

    Resistance exercise is an activity performed by individuals interested in competition, those who wish to improve muscle mass and strength for other sports, and for individuals interested in improving their strength and physical appearance. In this review we present information suggesting that phosphocreatine depletion, intramuscular acidosis and carbohydrate depletion are all potential causes of the fatigue during resistance exercise. In addition, recommendations are provided for nutritional interventions, which might delay muscle fatigue during this type of activity.

  9. High frequency guided waves for hidden fatigue crack growth monitoring in multi-layer aerospace structures

    Science.gov (United States)

    Chan, Henry; Fromme, Paul

    2015-03-01

    Varying loading conditions of aircraft structures result in stress concentration at fastener holes, where multi-layered components are connected, possibly leading to the development of fatigue cracks. High frequency guided waves propagating along the structure allow for the non-destructive testing of such components, e.g., aircraft wings. However, the sensitivity for the detection of small, potentially hidden, fatigue cracks has to be ascertained. The type of multi-layered model structure investigated consists of two adhesively bonded aluminium plate-strips. Fatigue experiments were carried out. The sensitivity of the high frequency guided wave modes to monitor fatigue crack growth at a fastener hole during cyclic loading was investigated, using both standard pulse-echo equipment and laser interferometry. The sensitivity and repeatability of the measurements were ascertained, having the potential for fatigue crack growth monitoring at critical and difficult to access fastener locations from a stand-off distance.

  10. 直肠癌结肠造口癌因性疲乏患者的自我管理效能及其影响因素%Influencing Factor and Self-management Efficacy of Patients with Carcinoma of the Rectum and Colostomy Cancer-related Fatigue

    Institute of Scientific and Technical Information of China (English)

    朱勤芬; 陆云; 赵春芳

    2015-01-01

    目的:了解直肠癌结肠造口癌因性疲乏患者的自我管理效能现状,分析其影响因素.方法便利抽样选择2012年8月至2014年8月昆山市中医医院直肠癌造口患者84例,采用造口自我管理效能问卷对其进行调查,运用多重线性回归分析患者自我效能的影响因素.结果造口患者自我效能总分为(75.00±10.41)分,为中等水平.影响造口患者自我效能的因素为年龄、婚姻状况、癌因性疲乏程度、造口自我接受程度、使用造口产品情况、肠造口时间、造口并发症、造口护理情况(均P<0.05).结论护理人员应采取有效措施控制直肠造口患者的癌因性疲乏,提高患者造口护理水平,以提高患者的自我管理效能和生活质量.%Objective To understand the influencing factor and current status of self-management efficacy of patients with carcinoma of the rectum and colostomy cancer-related fatigue.Methods By converence sampling,84 patients were selected and investigated by using stoma self-management efficacy question-naire,and influencing factors were analyzed by using multiple linear regression analysis method.Results The overall score of stoma self-management efficacy was (75.00±10.41),which was in the moderate level. The influencing factors were age,marital status,level of cancer-related fatigue,self-acceptance level of sto-ma,the stoma bag usage,stoma time,complication and stoma nursing(all P<0.05).Conclusion Nursing staff should take effective measure to control the colostomy cancer-related fatigue,increasing the patient’s stoma nursing level and to improving the self-management efficacy and quality of life.

  11. Effect of transcutanclus electrical acupoint stimulation used to alleviate cancer related fatigue in cancer chemotherapy patients%简易式经皮穴位电刺激缓解肿瘤患者癌因性疲乏的效果

    Institute of Scientific and Technical Information of China (English)

    孙秋子

    2011-01-01

    Objective To evaluate the effectiveness of transcutanclus electrical acupoint stimulation used to alleviate cancer related fatigue in cancer-chemotherapy patients and improve the quality of cancer patients' life.Methods Gastrointestinal-cancer hospitalized patients,with chemotherapy,who felt fatigue,were randomly assigned to experimental group and control group.The control group used conventional treatment and care.The experimental group,on the same baseline,used TEAS treatment (acupoints:Xuehai,Zusanli and Sanyinjiao).Patients were observed before and after intervention.The piper fatigue scale (Chinese version) was used to score and determine the effect.Results All dimension scores and total scores were not different ( P > 0.05 ) ; Fatigue dimension in experimental group was (6.85 ±0.21) before intervention and (6.76 ±0.13) after intervention,and the different was significant (t =2.171,P <0.05).Behavioral fatigue score and total piper fatigue score were (5.53 ±0.18),and (6.10 ±0.09),respectively,and (5.65 ±0.22),(6.17 ±0.11) in control group,the differences were significant (t =2.275,2.615,respectively,P <0.05).In behavioral,cognitive,emotional fatigue dimensions,there were no difference (P >0.05).Conclusions TEAS is effective to those cancer related fatigue patients with chemotherapy.However,there are individual differences.Further studies are needed.%目的 探讨经皮穴位电刺激缓解化疗患者癌因性疲乏的效果,提高肿瘤患者的生活质量.方法 将60例消化道肿瘤化疗患者,随机分为观察组(n=30)和对照组(n=30).对照组选用常规治疗和护理,观察组在此基础上采用经皮穴位电刺激治疗.比较两组患者治疗前后Piper疲乏量表评分变化.结果 两组患者干预前Piper疲乏量表各维度及总分比较差异均无统计学意义(P>0 05);观察组躯体疲乏维度干预前得分为(6.85±0.21)分,干预后为(6.76±0.13)分,差异有统计学意义(t=2.171,P<0.05);行为疲

  12. Shakedown based model for high-cycle fatigue of shape memory alloys

    Science.gov (United States)

    Gu, Xiaojun; Moumni, Ziad; Zaki, Wael; Zhang, Weihong

    2016-11-01

    The paper presents a high-cycle fatigue criterion for shape memory alloys (SMAs) based on shakedown analysis. The analysis accounts for phase transformation as well as reorientation of martensite variants as possible sources of fatigue damage. In the case of high-cycle fatigue, once the structure has reached an asymptotic state, damage is assumed to become confined at the mesoscopic scale, or the scale of the grain, with no discernable inelasticity at the macroscopic scale. Using a multiscale approach, a high-cycle fatigue criterion analogous to the Dang Van model (Dang Van 1973) for elastoplastic metals is derived for SMAs obeying the Zaki-Moumni model for SMAs (Zaki and Moumni 2007a). For these alloys, a safe domain is established in stress deviator space, consisting of a hypercylinder with axis parallel to the direction of martensite orientation at the mesoscopic scale. Safety with regard to high-cycle fatigue, upon elastic shakedown, is conditioned by the persistence of the macroscopic stress path at every material point within the hypercylinder, whose size depends on the volume fraction of martensite. The proposed criterion computes a fatigue factor at each material point, indicating its degree of safeness with respect to high cycle fatigue.

  13. Fatigue of Austempered Ductile Iron with Two Strength Grades in Very High Cycle Regime

    Science.gov (United States)

    Zhang, Jiwang; Li, Wei; Song, Qingpeng; Zhang, Ning; Lu, Liantao

    2016-03-01

    In this study, Austempered ductile irons (ADIs) with two different strength grades were produced and the fatigue properties were measured at 109 cycles. The results show that the S-N curves give a typical step-wise shape and there is no fatigue limit in the very high cycle fatigue regime. The two grades ADI have the similar fracture behaviors and fatigue failure can initiate from defects at specimen surface and subsurface zone. On the fracture surfaces of some specimens, the `granular-bright-facet' area with rich carbon distribution is observed in the vicinity of the defect. The microstructure affects the crack behaviors at the early propagation stage. The ADI with upper and lower bainite shows higher fatigue strength compared with the ADI with coarse upper bainite.

  14. Effect of microstructure on high-cycle fatigue properties of Alloy718 plates

    Science.gov (United States)

    Ono, Y.; Yuri, T.; Nagashima, N.; Ogata, T.; Nagao, N.

    2015-12-01

    Effect of microstructure on high-cycle fatigue properties of Alloy718 were investigated at 77 K by using samples with three different microstructures; fine-grained (FG), coarse-grained (CG) and bimodal-grained (BG) ones. The BG sample consisted of FG and CG microstructural regions and grain sizes of those regions were close to those of the FG and the CG samples, respectively. High-cycle fatigue strength of the FG sample was higher than that of the CG sample. High-cycle fatigue strength of the BG sample was clearly lower than that of the FG sample and almost the same as that of the CG one. Flat area (facet) was found at fatigue crack initiation site in all specimens. Facet size was similar to the grain size and found to be almost same in the CG and the BG samples. Observations of the microstructure beneath the fatigue crack initiation site of the BG sample revealed that the facet corresponds to transgranular cracking in the course grain, meaning that fatigue crack initiated at the coarse grain in the BG sample. It is deduced that the high-cycle fatigue strength of Alloy 718 with the BG microstructure is strongly affected by that of the CG region in that material.

  15. Effects of High Mean Stress on High-cycle Fatigue Behavior of PWA 1480

    Science.gov (United States)

    Majumdar, S.; Antolovich, S. D.; Milligan, W. W.

    1985-01-01

    PWA 1480 is a potential candidate material for use in the high-pressure fuel turbine blade of the space shuttle main engine. As an engine material it will be subjected to high-cycle fatigue loading superimposed on a high mean stress due to combined centrifugal and thermal loadings. The present paper describes the results obtained in an ongoing program at the Argonne National Laboratory, sponsored by NASA Lewis, to determine the effects of a high mean stress on the high-cycle fatigue behavior of this material. Straight-gauge high-cycle fatigue specimens, 0.2 inch in diameter and with the specimen axis in the 001 direction, were supplied by NASA Lewis. The nominal room temperature yield and ultimate strength of the material were 146 and 154 ksi, respectively. Each specimen was polished with 1-micron diamond paste prior to testing. However, the surface of each specimen contained many pores, some of which were as large as 50 micron. In the initial tests, specimens were subjected to axial-strain-controlled cycles. However, very little cyclic plasticity was observed.

  16. Fatigue Life of High Performance Grout for Wind Turbine Grouted Connection in Wet or Dry Environment

    DEFF Research Database (Denmark)

    Sørensen, Eigil V.; Westhof, Luc; Yde, Elo;

    Grouted connections of monopile supported offshore wind turbine structures are subjected to loads leading to very high oscillating service stresses in the grout material. The fatigue capacity of a high performance cement based grout was tested by dynamic compressive loading of cylindrical specimens...... at varying levels of cyclic frequency and load. The fatigue tests were performed in two series: one with the specimens in air and one with the specimens submerged in water during the test. The fatigue life of the grout, in terms of the number of cycles to failure, was found to be significantly shorter when...... tested in water than when tested in air....

  17. FEM Techniques for High Stress Detection in Accelerated Fatigue Simulation

    Science.gov (United States)

    Veltri, M.

    2016-09-01

    This work presents the theory and a numerical validation study in support to a novel method for a priori identification of fatigue critical regions, with the aim to accelerate durability design in large FEM problems. The investigation is placed in the context of modern full-body structural durability analysis, where a computationally intensive dynamic solution could be required to identify areas with potential for fatigue damage initiation. The early detection of fatigue critical areas can drive a simplification of the problem size, leading to sensible improvement in solution time and model handling while allowing processing of the critical areas in higher detail. The proposed technique is applied to a real life industrial case in a comparative assessment with established practices. Synthetic damage prediction quantification and visualization techniques allow for a quick and efficient comparison between methods, outlining potential application benefits and boundaries.

  18. Notch fatigue behavior: Metallic glass versus ultra-high strength steel

    Science.gov (United States)

    Wang, X. D.; Qu, R. T.; Wu, S. J.; Duan, Q. Q.; Liu, Z. Q.; Zhu, Z. W.; Zhang, H. F.; Zhang, Z. F.

    2016-01-01

    Studying the effect of notch on the fatigue behavior of structural materials is of significance for the reliability and safety designing of engineering structural components. In this work, we conducted notch fatigue experiments of two high-strength materials, i.e. a Ti32.8Zr30.2Ni5.3Cu9Be22.7 metallic glass (MG) and a 00Ni18Co15Mo8Ti ultra-high strength steel (CM400 UHSS), and compared their notch fatigue behavior. Experimental results showed that although both the strength and plasticity of the MG were much lower than those of the UHSS, the fatigue endurance limit of the notched MG approached to that of the notched UHSS, and the fatigue ratio of the notched MG was even higher. This interesting finding can be attributed to the unique shear banding mechanism of MG. It was found that during fatigue process abundant shear bands formed ahead of the notch root and in the vicinity of the crack in the notched MG, while limited plastic deformation was observed in the notched UHSS. The present results may improve the understanding on the fatigue mechanisms of high-strength materials and offer new strategies for structural design and engineering application of MG components with geometrical discontinuities. PMID:27752136

  19. Notch fatigue behavior: Metallic glass versus ultra-high strength steel

    Science.gov (United States)

    Wang, X. D.; Qu, R. T.; Wu, S. J.; Duan, Q. Q.; Liu, Z. Q.; Zhu, Z. W.; Zhang, H. F.; Zhang, Z. F.

    2016-10-01

    Studying the effect of notch on the fatigue behavior of structural materials is of significance for the reliability and safety designing of engineering structural components. In this work, we conducted notch fatigue experiments of two high-strength materials, i.e. a Ti32.8Zr30.2Ni5.3Cu9Be22.7 metallic glass (MG) and a 00Ni18Co15Mo8Ti ultra-high strength steel (CM400 UHSS), and compared their notch fatigue behavior. Experimental results showed that although both the strength and plasticity of the MG were much lower than those of the UHSS, the fatigue endurance limit of the notched MG approached to that of the notched UHSS, and the fatigue ratio of the notched MG was even higher. This interesting finding can be attributed to the unique shear banding mechanism of MG. It was found that during fatigue process abundant shear bands formed ahead of the notch root and in the vicinity of the crack in the notched MG, while limited plastic deformation was observed in the notched UHSS. The present results may improve the understanding on the fatigue mechanisms of high-strength materials and offer new strategies for structural design and engineering application of MG components with geometrical discontinuities.

  20. 有氧运动结合渐进性肌肉放松训练对肺癌化疗患者癌因性疲乏的影响*%Effect of aerobic exercise and progressive relaxation training on cancer-related fatigue in lung cancer patients during chemotherapy

    Institute of Scientific and Technical Information of China (English)

    张营; 张静

    2015-01-01

    目的:探讨有氧运动结合渐进性肌肉放松训练对肺癌化疗患者癌因性疲乏的影响。方法将60例出现癌因性疲乏的肺癌化疗患者采用随机数字表法分为干预组和对照组,每组各30例,对照组接受常规护理,干预组在常规护理的基础上给予6周有氧运动结合渐进性肌肉放松训练干预。干预前后采用Piper疲乏量表(Piper fatigue scale,PFS)对两组患者进行效果评价。结果干预前两组患者癌因性疲乏总分及各维度得分比较,均P>0.05,差异无统计学意义;干预后两组患者癌因性疲乏总分及各维度得分比较,均P<0.01,差异具有统计学意义,干预组患者得分明显低于对照组;干预组患者干预前后癌因性疲乏总分及各维度比较,均P<0.01,差异具有统计学意义,干预后得分明显低于干预前;对照组干预前后癌因性疲乏除了情感、感觉维度得分比较,均P<0.05,差异具有统计学意义,得分明显低于干预前外,总分及其他维度比较,均P>0.05,差异无统计学意义。结论有氧运动结合渐进性肌肉放松训练能有效缓解患者疲乏程度,改善身体功能,提高患者生活质量。%Objective To explore the effect of aerobic exercise and progressive relaxation training on cancer-related fatigue in lung cancer patients during chemotherapy. Methods Sixty lung cancer patients undergoing chemotherapy were randomly assigned to an experiment group (n=30) and control group (n=30). The patients in the study group received regular nursing plus 6 weeks aerobic exercise intervention and progressive relaxation training, while the patients in the control group only received regular nursing care. The effect of intervention was evaluated by the Piper fatigue scale (PFS). Results Before the intervention, three were no difference in the PFS scores and all dimentions scores between the two group. After the intervention

  1. An Investigation on Fatigue in High-Strength Steel Offshore Structures

    DEFF Research Database (Denmark)

    Agerskov, Henning; Petersen, R.I.; Lopez Martinez, L.

    1997-01-01

    In the present investigation, the fatigue life of offshore steel structures in high-strength steel is studied. The material used has a yield stress of 800-1000 MPa, and high weldability and toughness properties. Of special interest is the fatigue life under a realistic stochastic loading....... In the experimental part of the investigation, fatigue test series have been carried through on both full-scale tubular joints and smaller welded plate test specimens, in high-strength steel as well as in conventional offshore structural steel. The present document gives a summary of the main results presented in two......, in general longer fatigue lives were obtained for the test specimens in high-strength steel than those obtained in corresponding tests on joints in conventional offshore structural steel....

  2. Non-local high cycle fatigue criterion for metallic materials with corrosion defects

    Directory of Open Access Journals (Sweden)

    May Mohamed El

    2014-06-01

    Full Text Available Designing structures against corrosion fatigue has become a key problem for many engineering structures evolving in complex environmental conditions of humidity (aeronautics, civil engineering …. In this study, we investigate the effect of corrosion defects on the high cycle fatigue (HCF strength of a martensitic stainless steel with high specific mechanical strength, used in aeronautic applications. A volumetric approach based on Crossland equivalent stress is proposed. This can be applied to any real defects.

  3. Locomotor muscle fatigue does not alter oxygen uptake kinetics during high-intensity exercise

    Directory of Open Access Journals (Sweden)

    James Hopker

    2016-10-01

    Full Text Available The slow component (VO2sc that develops during high-intensity aerobic exercise is thought to be strongly associated with locomotor muscle fatigue. We sought to experimentally test this hypothesis by pre-fatiguing the locomotor muscles used during subsequent high-intensity cycling exercise. Over two separate visits, eight healthy male participants were asked to either perform a non-metabolically stressful 100 intermittent drop-jumps protocol (pre fatigue condition or rest for 33 minutes (control condition according to a random and counterbalanced order. Locomotor muscle fatigue was quantified with 6-second maximal sprints at a fixed pedaling cadence of 90 rev·min-1. Oxygen kinetics and other responses (heart rate, capillary blood lactate concentration and rating of perceived exertion, RPE were measured during two subsequent bouts of 6 min cycling exercise at 50% of the delta between the lactate threshold and VO2max determined during a preliminary incremental exercise test. All tests were performed on the same cycle ergometer. Despite significant locomotor muscle fatigue (P = 0.03, the VO2sc was not significantly different between the pre fatigue (464 ± 301 mL·min-1 and the control (556 ± 223 mL·min-1 condition (P = 0.50. Blood lactate response was not significantly different between conditions (P = 0.48 but RPE was significantly higher following the pre-fatiguing exercise protocol compared with the control condition (P < 0.01 suggesting higher muscle recruitment. These results demonstrate experimentally that locomotor muscle fatigue does not significantly alter the VO2 kinetic response to high intensity aerobic exercise, and challenge the hypothesis that the VO2sc is strongly associated with locomotor muscle fatigue.

  4. Fatigue behavior in austenitic stainless steels in high-temperature water

    Science.gov (United States)

    Smith, Jean Laverty

    The fatigue life of Type 304 and Type 316NG austenitic stainless steel has been shown to be significantly lower in light water reactor environments than in air at 288°C. The focus of this study was to determine the effect of dissolved oxygen (DO) on fatigue crack initiation and early crack growth at 288°C using fully-reversed, constant strain, axial fatigue tests. The fatigue tests were chosen to evaluate fracture surface appearance, fatigue crack lengths, and fatigue crack growth rates. Additional studies were conducted to evaluate the oxide film growth kinetics of Type 304 and Type 316NG stainless steel in high-temperature water. Corrosion coupons were exposed for intervals up to 50 days to high-temperature water at 288°C with two different levels of dissolved oxygen. The coupons were evaluated for weight change, oxide film thickness, and oxide film composition. The fatigue testing and oxide evaluations conducted in this study indicate that in low-DO water, the bulk environment does not allow a passive film to form, and newly created metal surfaces do not oxidize. Fatigue cracks propagate as Mode I tensile cracks normal to the stress axis from the onset. The apparent lack of Stage I crack growth in low-DO water accounts for the significant reduction in life in this environment as compared to air. In high-DO water, the bulk environment supports the formation of a passive film and prevents the evolution of hydrogen. Crack growth initially occurs only along primary slip planes at angles 45° to the applied stress. As the crack length increases, the crack tip environment becomes increasingly independent of the bulk environment, water at the crack tip becomes unstable, and the newly created surfaces no longer re-oxidize. Subsequently, the increasing stress intensity allows slip to occur on additional planes, and the fatigue crack propagates as a Mode I tensile crack.

  5. Indefatigable: an erect coralline alga is highly resistant to fatigue.

    Science.gov (United States)

    Denny, Mark; Mach, Katharine; Tepler, Sarah; Martone, Patrick

    2013-10-15

    Intertidal organisms are subjected to intense hydrodynamic forces as waves break on the shore. These repeated insults can cause a plant or animal's structural materials to fatigue and fail, even though no single force would be sufficient to break the organism. Indeed, the survivorship and maximum size of at least one species of seaweed is set by the accumulated effects of small forces rather than the catastrophic imposition of a single lethal force. One might suppose that fatigue would be especially potent in articulated coralline algae, in which the strain of the entire structure is concentrated in localized joints, the genicula. However, previous studies of joint morphology suggest an alternative hypothesis. Each geniculum is composed of a single tier of cells, which are attached at their ends to the calcified segments of the plant (the intergenicula) but have minimal connection to each other along their lengths. This lack of neighborly attachment potentially allows the weak interfaces between cells to act as 'crack stoppers', inhibiting the growth of fatigue cracks. We tested this possibility by repeatedly loading fronds of Calliarthron cheilosporioides, a coralline alga common on wave-washed shores in California. When repeatedly loaded to 50-80% of its breaking strength, C. cheilosporioides commonly survives more than a million stress cycles, with a record of 51 million. We show how this extraordinary fatigue resistance interacts with the distribution of wave-induced water velocities to set the limits to size in this species.

  6. Fatigue crack Behaviour in a High Strength Tool Steel

    DEFF Research Database (Denmark)

    Højerslev, Christian; Carstensen, Jesper V.; Brøndsted, Povl

    2002-01-01

    value of maximally 80% of the yield strength of the steel. The size of this carbide damage zone increases with increasing load amplitude, and the zone is apparently associated with crack nucleation. On fatigue crack propagation plastic deformation of the matrix occurs in a radius of approximately 4...

  7. Structural strength analysis and fatigue life prediction of traction converter box in high-speed EMU

    Science.gov (United States)

    Tan, Qin; Li, Qiang

    2017-01-01

    The method of building the FEA model of traction converter box in high-speed EMU and analyzing the static strength and fatigue strength of traction converter box based on IEC 61373-2010 and EN 12663 standards is presented in this paper. The load-stress correlation coefficients of weak points is obtained by FEA model, applied to transfer the load history of traction converter box to stress history of each point. The fatigue damage is calculated based on Miner's rule and the fatigue life of traction converter box is predicted. According to study, the structural strength of traction converter box meets design requirements.

  8. A method for calculation of finite fatigue life under multiaxial loading in high-cycle domain

    Directory of Open Access Journals (Sweden)

    M. Malnati

    2014-04-01

    Full Text Available A method for fatigue life assessment in high-cycle domain under multiaxial loading is presented in this paper. This approach allows fatigue assessment under any kind of load history, without limitations. The methodology lies on the construction - at a macroscopic level - of an “indicator” in the form of a set of cycles, representing plasticity that can arise at mesoscopic level throughout fatigue process. During the advancement of the loading history new cycles are created and a continuous evaluation of the damage is made.

  9. Fatigue Life of High Performance Grout in Dry and Wet Environment for Wind Turbine Grouted Connections

    DEFF Research Database (Denmark)

    Sørensen, Eigil V.

    2011-01-01

    the fatigue life of a high performance cement based grout was tested by dynamic compressive loading of cylindrical specimens at varying levels of cyclic frequency and load. The fatigue tests were performed in two series, one with the specimens tested in air and one with the specimens submerged in water during...... the test. The fatigue life of the grout, in terms of the number of cycles to failure, was found to be significantly shorter when tested in water than when tested in air, particularly at low frequency....

  10. Fretting fatigue behavior of high-strength steel monostrands under bending load

    DEFF Research Database (Denmark)

    Winkler, Jan; Georgakis, Christos T.; Fischer, Gregor

    2015-01-01

    In this paper, the fretting fatigue behavior of pretensioned high-strength steel monostrands is investigated. To measure the local deformations on the strands, a novel method based on the digital image correlation (DIC) technique was used to quantify the relative movement between individual wires...... along the length of the monostrand. Information about the monostrand bending stiffness and the extent of relative displacement between core and outer wires of a monostrand undergoing flexural deformations is provided. From the series of dynamic fatigue tests, a fretting fatigue spectrum is derived...

  11. Polymorphism attribution of cSNPs in cancer-related genes located in loss regions with a high frequency of HCC between HBV and health groups

    Institute of Scientific and Technical Information of China (English)

    WANG Juan; NI Hong; CHEN Li; CHEN Chengbin; SONG Wenqin

    2007-01-01

    Cancer-related genes harbored in the loss regions containing a high frequency of hepatocellular carcinoma (HCC) were selected.Related information was gathered and the coding single nucleotide polymorphism (cSNP) sequences were obtained from the single nucleotide polymorphism (SNP) database.The appropriate primers and oligonucleotide probes were then designed in accordance with the SNP sites,and subsequently,the gene chips for detecting SNPs were constructed.Genomic DNA was extracted from blood samples of healthy controls and from patients with HBV infection.The sequences,including the SNPs,were amplified via polymerase chain reaction (PCR) and labeled using digoxigenin deoxyuridine tri-phosphate (Dig-dUTP).The labeled products were then hybridized with the SNP chips.Results confirmed that the differences in allele frequencies of three SNPs EGFL3 (rs947345),Caspase9 (rs2308950),and E2F2 (rs3218171) were distinct between HBV-infected patients and controls,suggesting that these SNPs ocuring in high frequency in HBV-infected individuals may be associated with susceptibility to HCC.

  12. Fatigue Performance of Advanced High-Strength Steels (AHSS) GMAW Joints

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Zhili [ORNL; Sang, Yan [AET Integration, Inc; Jiang, Cindy [AET Integration, Inc; Chiang, Dr. John [Ford Motor Company; Kuo, Dr. Min [MIttal Steel

    2009-01-01

    The fatigue performance of gas metal arc welding (GMAW) joints of advanced high strength steels (AHSS) are compared and analyzed. The steel studied included a number of different grades of AHSS and baseline mild steels: DP600, DP780, DP980, M130, M220, solution annealed boron steel, fully hardened boron steels, HSLA690 and DR210 (a mild steel). Fatigue testing was conducted under a number of nominal stress ranges to obtain the S/N curves of the weld joints. A two-phase analytical model is developed to predict the fatigue performance of AHSS welds. It was found that there are appreciable differences in the fatigue S/N curves among different AHSS joints made using the same welding practices, suggesting that the local microstructure in the weld toe and root region plays non-negligible role in the fatigue performance of AHSS welds. Changes in weld parameters can influence the joint characteristics which in turn influence fatigue life of the weld joints, particularly of those of higher strength AHSS. The analytical model is capable of reasonably predicting the fatigue performance of welds made with various steel grades in this study.

  13. Fatigue crack growth behavior of the simulated HAZ of 800 MPa grade high-performance steel

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Sanghoon [Division of Materials Science and Engineering, Hanyang University, 17 Haengdang-dong, Seongdong-gu, Seoul 133-791 (Korea, Republic of); Kang, Donghwan; Kim, Tae-Won [School of Mechanical Engineering, Hanyang University, 17 Haengdang-dong, Seongdong-gu, Seoul 133-791 (Korea, Republic of); Lee, Jongkwan [Research Institute of Industrial Science and Technology, 75-9, Youngcheon, Dongtan, Hwaseong, Gyeonggi-do 445-813 (Korea, Republic of); Lee, Changhee, E-mail: chlee@hanyang.ac.kr [Division of Materials Science and Engineering, Hanyang University, 17 Haengdang-dong, Seongdong-gu, Seoul 133-791 (Korea, Republic of)

    2011-03-15

    Research highlights: {yields} Fatigue crack resistances of HSB800 base steel and HAZs: Base steel > FGHAZ > CGHAZ > ICCGHAZ. {yields} In the case of ICCGHAZ, fatigue cracks are rapidly initiated and propagated through massive M-A constituents. {yields} Fatigue crack growth rate of CGHAZ was faster than that of FGHAZ, mainly due to the coarsened prior austenite grain and martensite packet. - Abstract: The present study focuses on the fatigue properties in the weld heat-affected zone (HAZ) of 800 MPa grade high-performance steel, which is commonly used in bridges and buildings. Single- and multi-pass HAZs were simulated by the Gleeble system. Fatigue properties were estimated using a crack propagation test under a 0.3 stress ratio and 0.1 load frequencies. The microstructures and fracture surfaces were analyzed by optical microscopy, scanning electron microscopy, and transmission electron microscopy. The results of the crack propagation test showed that the fatigue crack growth rate of coarse-grained HAZ (CGHAZ) was faster than fine-grained HAZ (FGHAZ), although both regions have identical fully martensite microstructures, because FGHAZ has smaller prior austenite grain and martensite packet sizes, which can act as effective barriers to crack propagation. The fatigue crack growth rate of intercritically reheated CGHAZ (ICCGHAZ) was the fastest among local zones in the HAZ, due to rapid crack initiation and propagation via the massive martensite-austenite (M-A) constituent.

  14. Fatigue behavior of press hardened Al-Si coated high strength steel

    Institute of Scientific and Technical Information of China (English)

    Wang Zijian; Gui Zhongxiang; Zhang Yisheng

    2014-01-01

    The fatigue behavior of press hardened Al-Si coated high strength steel has been investigated,and the fatigue strength turns out to be about 1 000 MPa. Surface morphology of fractured and non-fractured speci-men has been observed,and the coating shows significant influence on the fatigue behavior. The difference of elastic modulus between coating and substrate led to the main cracks perpendicular to the loading direction. The coating close to fracture exfoliated thinly,while the coating far away from the fracture kept integrated. Though the specimen was polished to obtain high surface quality,3 types of cracks occurred during the fatigue test. What’s more,inclusion particles were proved to play a crucial role in causing these cracks.

  15. Fatigue Life of High Performance Grout in Dry and Wet Environment for Wind Turbine Grouted Connections

    DEFF Research Database (Denmark)

    Sørensen, Eigil V.

    2011-01-01

    The cementitious material in grouted connections of offshore monopile wind turbine structures is subjected to very high oscillating service stresses. The fatigue capacity of the grout therefore becomes essential to the performance and service life of the grouted connection. In the present work...... the fatigue life of a high performance cement based grout was tested by dynamic compressive loading of cylindrical specimens at varying levels of cyclic frequency and load. The fatigue tests were performed in two series, one with the specimens tested in air and one with the specimens submerged in water during...... the test. The fatigue life of the grout, in terms of the number of cycles to failure, was found to be significantly shorter when tested in water than when tested in air, particularly at low frequency....

  16. Fatigue performance of laser additive manufactured Ti-6Al-4V in very high cycle fatigue (VHCF regime up to 109 cycles

    Directory of Open Access Journals (Sweden)

    Eric eWycisk

    2015-12-01

    Full Text Available Additive manufacturing technologies are in the process of establishing themselves as an alternative production technology to conventional manufacturing such as casting or milling. Especially laser additive manufacturing (LAM enables the production of metallic parts with mechanical properties comparable to conventionally manufactured components. Due to the high geometrical freedom in LAM the technology enables the production of ultra-light weight designs and therefore gains increasing importance in aircraft and space industry. The high quality standards of these industries demand predictability of material properties for static and dynamic load cases. However, fatigue properties especially in the very high cycle fatigue regime until 109 cycles have not been sufficiently determined yet. Therefore this paper presents an analysis of fatigue properties of laser additive manufactured Ti-6Al-4V under cyclic tension-tension until 107 cycles and tension-compression load until 109 cycles.For the analysis of laser additive manufactured titanium alloy Ti-6Al-4V Woehler fatigue tests under tension-tension and tension-compression were carried out in the high cycle and very high cycle fatigue regime. Specimens in stress-relieved as well as hot-isostatic-pressed conditions were analyzed regarding crack initiation site, mean stress sensitivity and overall fatigue performance. The determined fatigue properties show values in the range of conventionally manufactured Ti-6Al-4V with particularly good performance for hot-isostatic-pressed additive-manufactured material. For all conditions the results show no conventional fatigue limit but a constant increase in fatigue life with decreasing loads. No effects of test frequency on life span could be determined. However, independently of testing principle, a shift of crack initiation from surface to internal initiation could be observed with increasing cycles to failure.

  17. Fatigue performance of laser additive manufactured Ti-6Al-4V in very high cycle fatigue (VHCF) regime up to 109 cycles

    Science.gov (United States)

    Wycisk, Eric; Siddique, Shafaqat; Herzog, Dirk; Walther, Frank; Emmelmann, Claus

    2015-12-01

    Additive manufacturing technologies are in the process of establishing themselves as an alternative production technology to conventional manufacturing such as casting or milling. Especially laser additive manufacturing (LAM) enables the production of metallic parts with mechanical properties comparable to conventionally manufactured components. Due to the high geometrical freedom in LAM the technology enables the production of ultra-light weight designs and therefore gains increasing importance in aircraft and space industry. The high quality standards of these industries demand predictability of material properties for static and dynamic load cases. However, fatigue properties especially in the very high cycle fatigue regime until 109 cycles have not been sufficiently determined yet. Therefore this paper presents an analysis of fatigue properties of laser additive manufactured Ti-6Al-4V under cyclic tension-tension until 107 cycles and tension-compression load until 109 cycles. For the analysis of laser additive manufactured titanium alloy Ti-6Al-4V Woehler fatigue tests under tension-tension and tension-compression were carried out in the high cycle and very high cycle fatigue regime. Specimens in stress-relieved as well as hot-isostatic-pressed conditions were analyzed regarding crack initiation site, mean stress sensitivity and overall fatigue performance. The determined fatigue properties show values in the range of conventionally manufactured Ti-6Al-4V with particularly good performance for hot-isostatic-pressed additive-manufactured material. For all conditions the results show no conventional fatigue limit but a constant increase in fatigue life with decreasing loads. No effects of test frequency on life span could be determined. However, independently of testing principle, a shift of crack initiation from surface to internal initiation could be observed with increasing cycles to failure.

  18. A New Multiaxial High-Cycle Fatigue Criterion Based on the Critical Plane for Ductile and Brittle Materials

    Science.gov (United States)

    Wang, Cong; Shang, De-Guang; Wang, Xiao-Wei

    2015-02-01

    An improved high-cycle multiaxial fatigue criterion based on the critical plane was proposed in this paper. The critical plane was defined as the plane of maximum shear stress (MSS) in the proposed multiaxial fatigue criterion, which is different from the traditional critical plane based on the MSS amplitude. The proposed criterion was extended as a fatigue life prediction model that can be applicable for ductile and brittle materials. The fatigue life prediction model based on the proposed high-cycle multiaxial fatigue criterion was validated with experimental results obtained from the test of 7075-T651 aluminum alloy and some references.

  19. Creep-Fatigue Damage Investigation and Modeling of Alloy 617 at High Temperatures

    Science.gov (United States)

    Tahir, Fraaz

    The Very High Temperature Reactor (VHTR) is one of six conceptual designs proposed for Generation IV nuclear reactors. Alloy 617, a solid solution strengthened Ni-base superalloy, is currently the primary candidate material for the tubing of the Intermediate Heat Exchanger (IHX) in the VHTR design. Steady-state operation of the nuclear power plant at elevated temperatures leads to creep deformation, whereas loading transients including startup and shutdown generate fatigue. A detailed understanding of the creep-fatigue interaction in Alloy 617 is necessary before it can be considered as a material for nuclear construction in ASME Boiler and Pressure Vessel Code. Current design codes for components undergoing creep-fatigue interaction at elevated temperatures require creep-fatigue testing data covering the entire range from fatigue-dominant to creep-dominant loading. Classical strain-controlled tests, which produce stress relaxation during the hold period, show a saturation in cycle life with increasing hold periods due to the rapid stress-relaxation of Alloy 617 at high temperatures. Therefore, applying longer hold time in these tests cannot generate creep-dominated failure. In this study, uniaxial isothermal creep-fatigue tests with non-traditional loading waveforms were designed and performed at 850 and 950°C, with an objective of generating test data in the creep-dominant regime. The new loading waveforms are hybrid strain-controlled and force-controlled testing which avoid stress relaxation during the creep hold. The experimental data showed varying proportions of creep and fatigue damage, and provided evidence for the inadequacy of the widely-used time fraction rule for estimating creep damage under creep-fatigue conditions. Micro-scale damage features in failed test specimens, such as fatigue cracks and creep voids, were quantified using a Scanning Electron Microscope (SEM) to find a correlation between creep and fatigue damage. Quantitative statistical

  20. Variable amplitude corrosion fatigue and fracture mechanics of weldable high strength jack-up steels

    OpenAIRE

    Etube, L. S.

    1998-01-01

    The tubular welded joints used in the construction of Offshore structures can experience millions of variable amplitude wave induced stress cycles during their operational life. Fatigue has been identified as the main cause of degradation of structural integrity in these structures. As a result, fatigue is an important consideration in their design. Jack-up legs are made from a range of high strength steels with yield strengths up to 70OMPa. These steels are thought to exhib...

  1. High Temperature Fatigue Crack Growth Rate of G91 Steel with Applying 30 Seconds Hold Time

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jong Bum; Park, Chang Gyu; Koo, Gyeong Hoi [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Lee, Jong Hoon [Sungkyunkwan University, Suwon (Korea, Republic of); Kim, Bum Joon [Osan Univ., Osan (Korea, Republic of)

    2015-05-15

    Subsection NH since 2004. The database of creep and creep-fatigue crack growth rate of G91 steel is necessary for the structural integrity evaluation of the SFR structures because the database of these properties of materials is insufficient through the world. Moreover, it is difficult to use the database which is gained by the research center of advanced countries because it is not to be opened. Therefore, it is necessary to make an effort to get the database of material properties. Creep-fatigue crack initiation and growth tests for a G91 tubular specimen, including a machined defect, have been performed by Kim and it attempted to assess a high temperature crack behavior of G91 side plate specimen by Lee. Creep-fatigue crack growth rate were compared in terms of different temperature range. Tests were performed at temperatures of 500, 550 and 600, respectively. Stress ratio was set to 0.1 and trapezoidal shape of stress condition was applied to the specimens to perform the creep-fatigue crack growth rate tests. Each specimen's surface was polished and fatigue pre-crack was manufactured by fatigue test before the high temperature test. And DCPD method was adopted to measure the crack length in the high temperature.

  2. High compressive pre-strains reduce the bending fatigue life of nitinol wire.

    Science.gov (United States)

    Gupta, Shikha; Pelton, Alan R; Weaver, Jason D; Gong, Xiao-Yan; Nagaraja, Srinidhi

    2015-04-01

    Prior to implantation, Nitinol-based transcatheter endovascular devices are subject to a complex thermo-mechanical pre-strain associated with constraint onto a delivery catheter, device sterilization, and final deployment. Though such large thermo-mechanical excursions are known to impact the microstructural and mechanical properties of Nitinol, their effect on fatigue properties is still not well understood. The present study investigated the effects of large thermo-mechanical pre-strains on the fatigue of pseudoelastic Nitinol wire using fully reversed rotary bend fatigue (RBF) experiments. Electropolished Nitinol wires were subjected to a 0%, 8% or 10% bending pre-strain and RBF testing at 0.3-1.5% strain amplitudes for up to 10(8) cycles. The imposition of 8% or 10% bending pre-strain resulted in residual set in the wire. Large pre-strains also significantly reduced the fatigue life of Nitinol wires below 0.8% strain amplitude. While 0% and 8% pre-strain wires exhibited distinct low-cycle and high-cycle fatigue regions, reaching run out at 10(8) cycles at 0.6% and 0.4% strain amplitude, respectively, 10% pre-strain wires continued to fracture at less than 10(5) cycles, even at 0.3% strain amplitude. Furthermore, over 70% fatigue cracks were found to initiate on the compressive pre-strain surface in pre-strained wires. In light of the texture-dependent tension-compression asymmetry in Nitinol, this reduction in fatigue life and preferential crack initiation in pre-strained wires is thought to be attributed to compressive pre-strain-induced plasticity and tensile residual stresses as well as the formation of martensite variants. Despite differences in fatigue life, SEM revealed that the size, shape and morphology of the fatigue fracture surfaces were comparable across the pre-strain levels. Further, the mechanisms underlying fatigue were found to be similar; despite large differences in cycles to failure across strain amplitudes and pre-strain levels, cracks

  3. Analysis of methods for determining high cycle fatigue strength of a material with investigation of titanium-aluminum-vanadium gigacycle fatigue behavior

    Science.gov (United States)

    Pollak, Randall D.

    Today, aerospace engineers still grapple with the qualitative and quantitative understanding of fatigue behavior in the design and testing of turbine-driven jet engines. The Department of Defense has taken a very active role in addressing this problem with the formation of the National High Cycle Fatigue Science & Technology Program in 1994. The primary goal of this program is to further the understanding of high cycle fatigue (HCF) behavior and develop methods in order to mitigate the negative impact of HCF on aerospace operations. This research supports this program by addressing the fatigue strength testing guidance currently provided by the DoD to engine manufacturers, with the primary goal to investigate current methods and recommend a test strategy to characterize the fatigue strength of a material at a specified number of cycles, such as the 109 design goal specified by MIL-HDBK-1783B, or range of cycles. The research utilized the benefits of numerical simulation to initially investigate the staircase method for use in fatigue strength testing. The staircase method is a commonly used fatigue strength test, but its ability to characterize fatigue strength variability is extremely suspect. A modified staircase approach was developed and shown to significantly reduce bias and scatter in estimates for fatigue strength variance. Experimental validation of this proposed test strategy was accomplished using a dual-phase Ti-6Al-4V alloy. The HCF behavior of a second material with a very different microstructure (beta annealed Ti-6Al-4V) was also investigated. The random fatigue limit (RFL) model, a recently developed analysis tool, was investigated to characterize stress-life behavior but found to have difficulty representing fatigue life curves with sharp transitions. Two alternative models (bilinear and hyperbolic) were developed based on maximum likelihood methods to better characterize the Ti-6Al-4V fatigue life behavior. These models provided a good fit to the

  4. Low cycle fatigue: high cycle fatigue damage accumulation in a 304L austenitic stainless steel; Endommagement et cumul de dommage en fatigue dans le domaine de l'endurance limitee d'un acier inoxydable austenitique 304L

    Energy Technology Data Exchange (ETDEWEB)

    Lehericy, Y

    2007-05-15

    The aim of this study was to evaluate the consequences of a Low Cycle Fatigue pre-damage on the subsequent fatigue limit of a 304L stainless steel. The effects of hardening and severe roughness (grinding) have also been investigated. In a first set of tests, the evolution of the surface damage induced by the different LCF pre-cycling was characterized. This has permitted to identify mechanisms and kinetics of damage in the plastic domain for different surface conditions. Then, pre-damaged samples were tested in the High Cycle Fatigue domain in order to establish the fatigue limits associated with each level of pre-damage. Results evidence that, in the case of polished samples, an important number of cycles is required to initiate surface cracks ant then to affect the fatigue limit of the material but, in the case of ground samples, a few number of cycles is sufficient to initiate cracks and to critically decrease the fatigue limit. The fatigue limit of pre-damaged samples can be estimated using the stress intensity factor threshold. Moreover, this detrimental effect of severe surface conditions is enhanced when fatigue tests are performed under a positive mean stress (author)

  5. Fatigue behavior of copper and selected copper alloys for high heat flux applications

    Energy Technology Data Exchange (ETDEWEB)

    Leedy, K.D.; Stubbins, J.F.; Singh, B.N.; Garner, F.A.

    1996-04-01

    The room temperature fatigue behavior of standard and subsize specimens was examined for five copper alloys: OFHC Cu, two CuNiBe alloys, a CuCrZr alloy, and a Cu-Al{sub 2}O{sub 3} alloy. Fatigue tests were run in strain control to failure. In addition to establishing failure lives, the stress amplitudes were monitored as a function of numbers of accrued cycles. The results indicate that the alloys with high initial yield strengths provide the best fatigue response over the range of failure lives examined in the present study: N{sub f} = 10{sup 3} to 10{sup 6}. In fact, the fatigue performance of the best alloys is dominated by the elastic portion of the strain range, as would be expected from the correlation of performance with yield properties. The alumina strengthened alloy and the two CuNiBe alloys show the best overall performance of the group examined here.

  6. Fatigue Behavior of High Speed Steel Roll Materials for Hot Rolling by Laser Impacting

    Institute of Scientific and Technical Information of China (English)

    ZHOU Li; SUN Da-le; LIU Chang-sheng; WU Qiong

    2006-01-01

    The fatigue behavior of high speed steel (HSS) roll materials for hot rolling was researched under water-cooling conditions by laser impacting. The microstructure of HSS sample and the morphologies of fatigue samples were observed by scanning electron microscope. The phase structure was detected by XRD. The morphology of situ oxide scale was observed by optical microscope, and the expansion coefficient was measured by TGA. The experiment results indicate that the cracks come into being at the carbide-matrix interface, but there are no cracks in the matrix after many times of laser impacting treatment, for the situ sample taken from the fractured roll surface, big carbides are more sensitive to the fatigue, and peel off prior to small ones. The relevant fatigue mechanisms are also discussed.

  7. High-cycle Fatigue Life Extension of Glass Fiber/Polymer Composites with Carbon Nanotubes

    Institute of Scientific and Technical Information of China (English)

    Christopher S Grimmer; C K H Dharan

    2009-01-01

    The present work shows that the addition of small volume fractions of multi-walled carbon nanotubes (CNTs) to the matrix results in a significant increase in the high-cycle fatigue life. It is proposed that carbon nanotubes tend to inhibit the formation of large cracks by nucleating nano-scale damage zones. In addition, the contribution to energy absorption from the fracture of nanotubes bridging across nano-scale cracks and from nanotube pull-out from the matrix are mechanisms that can improve the fatigue life. An energy-based model was proposed to estimate the additional strain energy absorbed in fatigue. The distributed nanotubes in the matrix appear to both distribute damage as well as inhibit damage propagation resulting in an overall improvement in the fatigue strength of glass fiber composites.

  8. Development of a Very High Cycle Fatigue (VHCF multiaxial testing device

    Directory of Open Access Journals (Sweden)

    M. Vieira

    2016-07-01

    Full Text Available The very high cycle region of the S-N fatigue curve has been the subject of intensive research on the last years, with special focus on axial, bending, torsional and fretting fatigue tests. Very high cycle fatigue can be achieved using ultrasonic exciters which allow for frequency testing of up to 30 kHz. Still, the multiaxial fatigue analysis is not yet developed for this type of fatigue analyses, mainly due to conceptual limitations of these testing devices. In this paper, a device designed to produce biaxial fatigue testing using a single piezoelectric axial exciter is presented, as well as the preliminary testing of this device. The device is comprised of a horn and a specimen, which are both attached to the piezoelectric exciter. The steps taken towards the final geometry of the device are presented. Preliminary experimental testing of the developed device is made using thermographic imaging, strain measurements and vibration speeds and indicates good behaviour of the tested specimen.

  9. Wind-Induced Fatigue Analysis of High-Rise Steel Structures Using Equivalent Structural Stress Method

    Directory of Open Access Journals (Sweden)

    Zhao Fang

    2017-01-01

    Full Text Available Welded beam-to-column connections of high-rise steel structures are susceptive to fatigue damage under wind loading. However, most fatigue assessments in the field of civil engineering are mainly based on nominal stress or hot spot stress theories, which has the disadvantage of dependence on the meshing styles and massive curves selected. To address this problem, in this paper, the equivalent structural stress method with advantages of mesh-insensitive quality and capability of unifying different stress-life curves (S-N curves into one is introduced to the wind-induced fatigue assessment of a large-scale complicated high-rise steel structure. The multi-scale finite element model is established and the corresponding wind loading is simulated. Fatigue life assessments using equivalent structural stress method, hot spot stress method and nominal stress method are performed, and the results are verified and comparisons are made. The mesh-insensitive quality is also verified. The results show that the lateral weld toe of the butt weld connecting the beam flange plate and the column is the location where fatigue damage most likely happens. Nominal stress method considers fatigue assessment of welds in a more global way by averaging all the stress on the weld section while in equivalent structural stress method and hot spot method local stress concentration can be taken into account more precisely.

  10. THE EFFECT OF MODERATE AND HIGH-INTENSITY FATIGUE ON GROUNDSTROKE ACCURACY IN EXPERT AND NON-EXPERT TENNIS PLAYERS

    Directory of Open Access Journals (Sweden)

    Mark Lyons

    2013-06-01

    Full Text Available Exploring the effects of fatigue on skilled performance in tennis presents a significant challenge to the researcher with respect to ecological validity. This study examined the effects of moderate and high-intensity fatigue on groundstroke accuracy in expert and non-expert tennis players. The research also explored whether the effects of fatigue are the same regardless of gender and player's achievement motivation characteristics. 13 expert (7 male, 6 female and 17 non-expert (13 male, 4 female tennis players participated in the study. Groundstroke accuracy was assessed using the modified Loughborough Tennis Skills Test. Fatigue was induced using the Loughborough Intermittent Tennis Test with moderate (70% and high-intensities (90% set as a percentage of peak heart rate (attained during a tennis-specific maximal hitting sprint test. Ratings of perceived exertion were used as an adjunct to the monitoring of heart rate. Achievement goal indicators for each player were assessed using the 2 x 2 Achievement Goals Questionnaire for Sport in an effort to examine if this personality characteristic provides insight into how players perform under moderate and high-intensity fatigue conditions. A series of mixed ANOVA's revealed significant fatigue effects on groundstroke accuracy regardless of expertise. The expert players however, maintained better groundstroke accuracy across all conditions compared to the novice players. Nevertheless, in both groups, performance following high-intensity fatigue deteriorated compared to performance at rest and performance while moderately fatigued. Groundstroke accuracy under moderate levels of fatigue was equivalent to that at rest. Fatigue effects were also similar regardless of gender. No fatigue by expertise, or fatigue by gender interactions were found. Fatigue effects were also equivalent regardless of player's achievement goal indicators. Future research is required to explore the effects of fatigue on

  11. Creep-fatigue of High Temperature Materials for VHTR: Effect of Cyclic Loading and Environment

    Energy Technology Data Exchange (ETDEWEB)

    Celine Cabet; L. Carroll; R. Wright; R. Madland

    2011-05-01

    Alloy 617 is the one of the leading candidate materials for Intermediate Heat eXchangers (IHX) of a Very High Temperature Reactor (VHTR). System start-ups and shut-downs as well as power transients will produce low cycle fatigue (LCF) loadings of components. Furthermore, the anticipated IHX operating temperature, up to 950°C, is in the range of creep so that creep-fatigue interaction, which can significantly increase the fatigue crack growth, may be one of the primary IHX damage modes. To address the needs for Alloy 617 codification and licensing, a significant creep-fatigue testing program is underway at Idaho National Laboratory. Strain controlled LCF tests including hold times up to 1800s at maximum tensile strain were conducted at total strain range of 0.3% and 0.6% in air at 950°C. Creep-fatigue testing was also performed in a simulated VHTR impure helium coolant for selected experimental conditions. The creep-fatigue tests resulted in failure times up to 1000 hrs. Fatigue resistance was significantly decreased when a hold time was added at peak stress and when the total strain was increased. The fracture mode also changed from transgranular to intergranular with introduction of a tensile hold. Changes in the microstructure were methodically characterized. A combined effect of temperature, cyclic and static loading and environment was evidenced in the targeted operating conditions of the IHX. This paper This paper reviews the data previously published by Carroll and co-workers in references 10 and 11 focusing on the role of inelastic strain accumulation and of oxidation in the initiation and propagation of surface fatigue cracks.

  12. Exceptional high fatigue strength in Cu-15at.%Al alloy with moderate grain size

    Science.gov (United States)

    Liu, Rui; Tian, Yanzhong; Zhang, Zhenjun; An, Xianghai; Zhang, Peng; Zhang, Zhefeng

    2016-06-01

    It is commonly proposed that the fatigue strength can be enhanced by increasing the tensile strength, but this conclusion needs to be reconsidered according to our study. Here a recrystallized α-Cu-15at.%Al alloy with moderate grain size of 0.62 μm was fabricated by cold rolling and annealing, and this alloy achieved exceptional high fatigue strength of 280 MPa at 107 cycles. This value is much higher than the fatigue strength of 200 MPa for the nano-crystalline counterpart (0.04 μm in grain size) despite its higher tensile strength. The remarkable improvement of fatigue strength should be mainly attributed to the microstructure optimization, which helps achieve the reduction of initial damage and the dispersion of accumulated damage. A new strategy of “damage reduction” was then proposed for fatigue strength improvement, to supplement the former strengthening principle. The methods and strategies summarized in this work offer a general pathway for further improvement of fatigue strength, in order to ensure the long-term safety of structural materials.

  13. High cycle fatigue properties of die-cast magnesium alloy AZ91D-1%MM

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The high cycle fatigue properties of the die-cast magnesium alloy AZ91D containing 1%mischmetal(mass fraction)at a fatigue ratio of 0.1 were investigated.The difference in the microstructure between the skin and core region of the die-cast magnesium alloy was analyzed by optical microscopy.The mechanical property tests indicate that the values of the tensile strength,elongation and hardness are 185 MPa,1.5%and HBS 70±3 at room temperature,respectively.The p-S-N curve(p=50%)of the die-cast magnesium alloy AZ91D-1%MM is determined and the mean fatigue strength corresponding to 3.8×105cycles is 70 MPa.A linear relation between S and Np in log scale between 103 and 106 cycles is written with a equation.The mechanical properties are influenced by the casting defects.The fatigue life of the samples with minor defects is near to the upper limit of the fatigue life data.The fatigue fracture surface of the samples with minor defects possesses the mixed characteristics of quasi-cleavage,lacerated ridge and dimple and it is briule fracture mode as a whole.

  14. Fatigue Performance of Microalloyed High-strength Rebar and Analysis of Fracture Mechanism

    Institute of Scientific and Technical Information of China (English)

    Peng-yan LU; Yu LIU; Hua-jie WU; Gang LIU; Xiang MENG; Yang XU

    2015-01-01

    Fatigue performance of hot-rolled ribbed-steel bar with the yield strength of 500 MPa (HRB500)was stud-ied with bend-rotating fatigue test at a stress ratio of R=-1 .It is determined by staircase method that its fatigue strength for 107 cycles is 451 MPa,which is higher than that of common carbon structural steel.This should be at-tributed to the fine-grain strengthening resulting from the high content of alloy element V and Thermo-Mechanical Control Process (TMCP).The S-N curve function is also obtained by nonlinear regression with three parameters power function.The fatigue fractures of the specimen were further analyzed with Scanning Electron Microscopy (SEM)and Energy Disperse Spectroscopy (EDS)to study the fracture mechanism.Taking into account microstruc-ture,hardness and cleanliness of the material,it implies that the fatigue fractures of HRB500 rebar all arise from surface substrates in which many brittle inclusions are contained,and that the fatigue crack propagation is principally based on the mechanism of quasi-cleavage fracture,because of the intracrystalline hard spots leading to stress con-centration and thus to the cracks.Moreover,the transient breaking area exhibits microvoid coalescence of ductile fracture due to the existing abundant inclusions.

  15. The significance of crack initiation stage in very high cycle fatigue of steels

    Energy Technology Data Exchange (ETDEWEB)

    Bergstroem, J. [Department of Materials Engineering, Karlstad University (Sweden); Burman, C.; Kazymyrovych, V.

    2010-04-15

    Different stages of the Very High Cycle Fatigue (VHCF) crack evolution in tool steels have been explored using a 20 kHz ultrasonic fatigue testing equipment. Extensive experimental data is presented describing VHCF behaviour, strength and crack initiating defects in an AISI H11 tool steel. Striation measurements are used to estimate fatigue crack growth rate, between 10{sup -8} and 10{sup -6} m/cycle, and the number of load cycles required for a crack to grow to critical dimensions. The growth of small fatigue cracks within the ''fish-eye'' is shown to be distinctively different from the crack propagation behaviour of larger cracks. More importantly, the crack initiation stage is shown to determine the total fatigue life, which emphasizes the inherent difficulty to detect VHCF cracks prior to failure. Several mechanisms for initiation and early crack growth are possible. Some of them are discussed here: crack development by local accumulation of fatigue damage at the inclusion - matrix interface, hydrogen assisted crack growth and crack initiation by decohesion of carbides from the matrix. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  16. Hazards and Safeguards of High Pressure Hydraulic Fatigue Testing

    Science.gov (United States)

    1990-07-01

    rew e I&64aN neem mde tliF by block mumber) The creation and transfer of hydraulic pressure at the 690-MPa (100,000-psi) level is in itself hazardous...than alloy steel, we have found that it is more notch sensitive to fatigue and drastically degrades with small constituent variations. To avoid this...I ATTN: SMCWV-PP DIRECTOR, PRODUCT ASSURANCE DIRECTORATE 1 ATTN: SMCWV-QA NOTE: PLEASE NOTIFY DIRECTOR, BENET LABORATORIES, ATTN: SMCAR-CCB-TL, OF ANY

  17. 国内关于有氧运动对患者癌因性疲乏干预性研究的文献质量评价%Critical appraisal of domestic intervention studies of aerobic exercise in cancer-related fatigue patients

    Institute of Scientific and Technical Information of China (English)

    王晓庆; 段培蓓; 梅思娟; 杨丽华

    2016-01-01

    Objective To analyze the quality of domestic intervention studies of aerobic exercise in cancer -related fatigue patients. Methods CBM,CNKI,Wan-fang data and VIP were searched using MESH words of "tumour","aerobic exercise" and "cancer - related fatigue". Modified Jadad scale was used for method-ology quality evaluation,and the 2010 division of CONSORT statement was used for comprehensive evaluation of articles included. Results Eighteen articles were included. The methodological quality of articles included was low,only 1 article got 3 points of Jadad scale,5 articles got 2 points,and the rest articles got less than 2 points. Further,the writing of articles included was lack of standardization. Conclusion Aerobic exercise can release the severity of cancer - related fatigue to a certain extent,but the mode of exercise is lack of normalization. The methodological quality of relative researches is low,and the writing is lack of standardization. Therefore,further studies are needed to explore the optimal exercise mode,the methodology research and writing quality should be improved,to meet the demand of evidence - based nursing.%目的:分析国内有关有氧运动对肿瘤患者癌因性疲乏干预性研究的现状及文献质量。方法以“肿瘤 OR 癌症”“有氧运动”“癌因性疲乏 OR 疲乏”为检索词,对中国生物医学数据库(CBM)、中国知网(CNKI)、万方数据库、维普数据库(VIP)进行检索;纳入文献采用改良后的 Jadad 量表进行方法学质量评价,采用 CONSORT 声明2010版本对文献报告质量进行综合评价。结果共检索出18篇符合纳入及排除标准的文献,纳入文献方法学质量较低,只有1篇文献 Jadad 评分为3分,5篇为2分,其余均低于2分;纳入研究报告书写欠规范。结论有氧运动能缓解癌因性疲乏的严重程度,但运动方式缺乏规范性;相关研究方法学质量较低,研究报告书写欠规范。因此,

  18. An investigation on fatigue in high-strength steel offshore structures

    DEFF Research Database (Denmark)

    Agerskov, Henning; Petersen, R.I.; Martinez, L. Lopez

    1998-01-01

    The fatigue life of offshore steel structures in high-strength steel is studied. The material used has a yield stress of 800-1000 MPa and high weldability and toughness properties. Of special interest is the fatigue life under a realistic stochastic loading. In the experimental part...... of the investigation, fatigue test series were carried out on both full scale tubular joints and smaller welded plate test specimens in high-strength steel as well as in conventional offshore structural steel. This paper gives a summary of the main results presented in two recent research reports [15, 16], from...... specimens in high-strength steel than those obtained in corresponding tests on joints in conventional offshore structural steel....

  19. Work fatigue and physiological symptoms in different occupations of high-elevation construction workers.

    Science.gov (United States)

    Chang, Fu-Lin; Sun, Yih-Min; Chuang, Kao-Hsing; Hsu, Der-Jen

    2009-07-01

    The objective of this study is to investigate whether work fatigue and physiological symptoms that high-elevation construction workers experience would be affected by the occupations. Questionnaires of demographic data and subjective fatigue symptoms as well as some physiological measurements were carried out, pre- and post-shift, on scaffolders, steel fixers, formworkers, electrician-plumbers, concreters and miscellaneous workers at a high-rise building construction site. This study found that some subjective fatigue symptoms coincide with the life style of some workers and that the extent of fatigue symptoms and physiological strains varies among different occupations of construction workers. Scaffolders, steel fixers and formworkers are categorized as physically demanding fatigue type of workers, while concreters, electrician-plumbers and miscellaneous workers as general type. The prevalence and occurrence of subjective fatigue symptoms indicate high-elevation workers have more complaints of "projection of physical impairment" than "drowsiness and dullness" and "difficulty in concentration". Some unexpected changes (i.e., post-shift measurements are greater than pre-shift ones) in some strength tests in scaffolders and concreters were consistent with the observations of how they exercised their bodies during work shift. Considerable variation of average heart rate among occupations was found, with scaffolders the highest and concreters the lowest. This study concludes that questionnaires of subjective fatigue symptoms and some physiological measurements can be used as indicators to predict the extent of strains or hazards which construction workers encounter. In terms of management program of safety and health, more attention should be paid to those physically demanding workers, such as scaffolders, workers with lower sense of safety and health, such as miscellaneous workers, and workers with older age, such as concreters.

  20. Low Cycle Fatigue Behaviors of Alloy 617 (INCONEL 617 Weldments for High Temperature Applications

    Directory of Open Access Journals (Sweden)

    Rando Tungga Dewa

    2016-04-01

    Full Text Available In this study, we comparatively investigate the low cycle fatigue behavior of Alloy 617 (INCONEL 617 weldments by gas tungsten arc welding process at room temperature and 800 °C in the air to support the qualification in high temperature applications of the Next Generation-IV Nuclear Plant. Axial total-strain controlled tests have been performed with the magnitude of strain ranges with a constant strain ratio (Rε = −1. The results of fatigue tests consistently show lower fatigue life with an increase in total strain range and temperature at all testing conditions. The reduction in fatigue life may result from the higher cyclic plastic strain accumulation and the material ductility at high temperature conditions. A constitutive behavior of high temperature by some cyclic hardening was observed. The occurrence of serrated yielding in the cyclic stress response was also observed, suggesting the influence of dynamic strain aging during high temperature. We evaluated a well-known life prediction model through the Coffin-Manson relationship. The results are well matched with the experimental data. In addition, low cycle fatigue cracking occurred in the weld metal region and initiated transgranularly at the free surface.

  1. The effect of moderate and high-intensity fatigue on groundstroke accuracy in expert and non-expert tennis players.

    Science.gov (United States)

    Lyons, Mark; Al-Nakeeb, Yahya; Hankey, Joanne; Nevill, Alan

    2013-01-01

    Exploring the effects of fatigue on skilled performance in tennis presents a significant challenge to the researcher with respect to ecological validity. This study examined the effects of moderate and high-intensity fatigue on groundstroke accuracy in expert and non-expert tennis players. The research also explored whether the effects of fatigue are the same regardless of gender and player's achievement motivation characteristics. 13 expert (7 male, 6 female) and 17 non-expert (13 male, 4 female) tennis players participated in the study. Groundstroke accuracy was assessed using the modified Loughborough Tennis Skills Test. Fatigue was induced using the Loughborough Intermittent Tennis Test with moderate (70%) and high-intensities (90%) set as a percentage of peak heart rate (attained during a tennis-specific maximal hitting sprint test). Ratings of perceived exertion were used as an adjunct to the monitoring of heart rate. Achievement goal indicators for each player were assessed using the 2 x 2 Achievement Goals Questionnaire for Sport in an effort to examine if this personality characteristic provides insight into how players perform under moderate and high-intensity fatigue conditions. A series of mixed ANOVA's revealed significant fatigue effects on groundstroke accuracy regardless of expertise. The expert players however, maintained better groundstroke accuracy across all conditions compared to the novice players. Nevertheless, in both groups, performance following high-intensity fatigue deteriorated compared to performance at rest and performance while moderately fatigued. Groundstroke accuracy under moderate levels of fatigue was equivalent to that at rest. Fatigue effects were also similar regardless of gender. No fatigue by expertise, or fatigue by gender interactions were found. Fatigue effects were also equivalent regardless of player's achievement goal indicators. Future research is required to explore the effects of fatigue on performance in tennis

  2. 癌性疲乏干预对提高乳腺癌术后患者生存质量的效果研究%Effects of cancer-related fatigue intervention on improving the quality of life in post-operative patients with breast cancer

    Institute of Scientific and Technical Information of China (English)

    陈旭东; 刘宝凤; 贾淑媛

    2012-01-01

    Objective To explore the effects of cancer-related fatigue (CRF) intervention on improving the quality of life in post-operative patients with breast cancer.Methods Seventy post-operative breast cancer patients were equally divided into the interventional group and the control group. Both groups received conventional nursing service,and the former one received additional cancer-related fatigue nursing intervention,including the CRF valuation,evidence-based nursing,emotion and information support,cognitive intervention,self-care mode and personalized care.Then cancer related fatigue and quality of life between both group patients before and after intervention were analyzed by applying simple fatigue rating scale and quality of life questionnaire.Results There was no significant difference between the score of PFS and QOL before the intervention (4.59 ± 1.66 vs 4.61 ± 1.70,P >0.05 ).After intervention,the score of PFS of the interventional group was significantly lower than that in the control group (4.66 ± 1.12 vs 5.52 ± 1.61 ; t =2.928,P <0.05).After intervention,the QOL of the interventional group including general health (60.82 ± 9.12 vs 54.05 ± 6.77 ),body function (66.76 ± 9.82 vs 60.58 ± 11.89 ),role function ( 64.39 ± 12.59 vs 58.24 ±12.09),motion function (65.62 ±8.31 vs 60.13 ±9.56),the cognition function(71.91 ±9.14 vs 65.30 ±11.92) and social function (66.75 ± 12.76 vs 60.82 ± 13.59) were significantly better than that of the control group (P < 0.05 ).Conclusions According to the nursing procedure,cancer-related fatigue intervention including the CRF valuation,analyze the CRF reasons and building up individuation intervention could alleviate CRF and improve the patients' QOL.%目的 探讨癌性疲乏(CRF)护理干预对乳腺癌术后患者生存质量的效果.方法 采用随机数字表法将70例乳腺癌术后患者随机分为干预组35例、对照组35例.对照组接受常规护理,观察组在接受常规护理的基础

  3. Comparison of Post Weld Treatment of High Strength Steel Welded Joints in Medium Cycle Fatigue

    DEFF Research Database (Denmark)

    Pedersen, Mikkel Melters; Mouritsen, Ole Ø.; Hansen, Michael Rygaard

    2010-01-01

    the stress range can exceed the yield-strength of ordinary structural steel, especially when considering positive stress ratios (R > 0). Fatigue experiments and qualitative evaluation of the different post-weld treatments leads to the selection of TIG dressing. The process of implementing TIG dressing......This paper presents a comparison of three post-weld treatments for fatigue life improvement of welded joints. The objective is to determine the most suitable post-weld treatment for implementation in mass production of certain crane components manufactured from very high-strength steel....... The processes investigated are: burr grinding, TIG dressing and ultrasonic impact treatment. The focus of this investigation is on the so-called medium cycle area, i.e. 10 000-500 000 cycles and very high stress ranges. In this area of fatigue design, the use of very high strength steel becomes necessary, since...

  4. High cycle fatigue crack propagation resistance and fracture toughness in ship steels (Short Communication

    Directory of Open Access Journals (Sweden)

    R.S. Tripathi

    2001-04-01

    Full Text Available In this paper, two grades of steel, viz., plain carbon steel and low alloy steel used in naval ships have been selected for studies on high cycle fatigue, crack propagation, stress intensity and crack opening displacement (COD. Specimen for high cycle fatigue was prepared as per IS: 1608. High cycle fatigue was carried out up to 50,000 cycles at 1000 kgfto 2000 kgfloads. Up to 2000 kgfloads, both the materials were observed within elastic zones. A number of paran1eters, including stress, strain and strain range, which indicate elastic behaviour of steels, have been considered. Low alloy steel specimen was prepared as per ASTM standard: E-399 and subjected to 5,00,000 cycles. Crack propagation, COD, stress intensity, load-cycle variations, load-COD relation, and other related paran1eters have been studied using a modem universal testing machine with state-of-the-art technology

  5. High-cycle fatigue behavior of Ti-5Al-2.5Sn ELI alloy forging at low temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Ono, Yoshinori; Yuri, Tetsumi; Ogata, Toshio; Demura, Masahiko [National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan); Matsuoka, Saburo [Kyushu University, 744, Motooka, Nishi-ku, Fukuoka, Fukuoka 819-0395 (Japan); Sunakawa, Hideo [Japan Aerospace Exploration Agency, 2-1-1 Sengen, Tsukuba, Ibaraki 305-8505 (Japan)

    2014-01-27

    High-cycle fatigue properties of Ti-5Al-2.5Sn Extra Low Interstitial (ELI) alloy forging were investigated at low temperatures. The high-cycle fatigue strength at low temperatures of this alloy was relatively low compared with that at ambient temperature. The crystallographic orientation of a facet formed at a fatigue crack initiation site was determined by electron backscatter diffraction (EBSD) method in scanning electron microscope (SEM) to understand the fatigue crack initiation mechanism and discuss on the low fatigue strength at low temperature. Furthermore, in terms of the practical use of this alloy, the effect of the stress ratio (or mean stress) on the high-cycle fatigue properties was evaluated using the modified Goodman diagram.

  6. Effect of strain rate and temperature at high strains on fatigue behavior of SAP alloys

    DEFF Research Database (Denmark)

    Blucher, J.T.; Knudsen, Per; Grant, N.J.

    1968-01-01

    Fatigue behavior of three SAP alloys of two nominal compositions (7 and 13% Al2O3) was studied in terms of strain rate and temperature at high strains; strain rate had no effect on life at 80 F, but had increasingly greater effect with increasing temperature above 500 F; life decreased with decre......Fatigue behavior of three SAP alloys of two nominal compositions (7 and 13% Al2O3) was studied in terms of strain rate and temperature at high strains; strain rate had no effect on life at 80 F, but had increasingly greater effect with increasing temperature above 500 F; life decreased...

  7. Study of high cycle fatigue of PVD surface-modified austempered ductile iron

    Energy Technology Data Exchange (ETDEWEB)

    Feng, H.P.; Lee, S.C.; Hsu, C.H.; Ho, J.M. [Tatung Inst. of Technol., Taipei (Taiwan, Province of China). Dept. of Mater. Eng.

    1999-05-25

    Austempered ductile iron (ADI) is made from ductile iron by an austempering treatment, and its main microstructure is ausferrite that is composed of acicular ferrite and high carbon austenite. The purpose of this experiment is to investigate the influence of different coating layers and the size of casting (mass effect) on the high-cycle fatigue properties of ADI. Specimens in two casting sizes of the same chemical composition were subjected to a high-toughness austempering treatment, then coated with TiN or TiCN hard films by a physical vapor deposition (PVD) process. The results showed that the fatigue limit of the small casting size ADI is 292 MPa for ADI coated with TiN and 306 MPa for ADI coated with TiCN, which are 16% and 22%, respectively, higher than that of the ADI without coating (251 MPa). For the large casting size ADI, the fatigue limits are 200, 214 and 217 MPa for ADI without coating, ADI coated with TiN and ADI coated with TiCN, respectively. ADI coated with TiN and with TiCN are 7% and 9% better than the uncoated. Thus, it is concluded that TiN and TiCN coatings by PVD can improve the high-cycle fatigue strength of ADI. This is due to the high surface hardness and possibly the ADI surface compressive residual stress as well. For the small casting size ADI, TiCN-coated specimens have a bit higher fatigue strengths and this might be attributed to the higher hardness of TiCN than TiN films. As to the effect of mass, it is found that the small casting size has better fatigue properties and benefits more from the coating films. This could have stemmed from the higher nodule count and its associated benefits in thinner castings. (orig.) 24 refs.

  8. Fatigue strength of truss girders made of very high strength steel

    NARCIS (Netherlands)

    Pijpers, R.J.M.; Kolstein, M.H.

    2010-01-01

    An effective application of Very High Strength Steel (VHSS) in civil engineering structures is expected in stiff, truss like structures, typically made of Circular Hollow Sections (CHS). Use of castings in combination with CHS could be promising for the design of highly fatigue resistant joints. Cas

  9. High frequency fatigue test of IN 718 alloy – microstructure and fractography evaluation

    Directory of Open Access Journals (Sweden)

    J. Belan

    2015-01-01

    Full Text Available INCONEL alloy 718 is a high-strength, corrosion-resistant nickel chromium material used at -253 °C to 705 °C for production of heat resistant parts of aero jet engine mostly. The fatigue test provided on this kind materials were done via low frequency loading up to this time. Nowadays, needs of results at higher volume of loading cycles leads to high frequency loading with aim to shorten testing time. Fatigue test of experimental material was carried out at frequency 20 kHz with stress ration R = - 1 (push – pull at room temperature. It was found that this superalloy can still fracture after exceeding 108 cycles. Besides fatigue test were microstructural characterisation and scanning electron microscopy (SEM fractography evaluation done.

  10. Development of high-cycle fatigue design curves for a cast aluminum alloy

    Science.gov (United States)

    Cooper, R. A.

    1979-01-01

    Life prediction curves for rocket engine pump parts were developed from the results of high-cycle fatigue tests run on cast-aluminum specimens. Notched and smooth specimens were cyclically tested at different mean stress levels at -320 F (78 K). The notch size and mean stress enveloped the design operating conditions. Local stress computed in the groove of the notched specimen was used to represent its fatigue strength. The von Mises criterion was used to determine effective cyclic stresses. The Goodman rule was applied to determine equivalent reversed alternating stresses. The procedure permitted the notched and smooth data sets to each be described by a single curve. High-cycle fatigue life curves were provided for the stress state, mean stress, and stress concentration spanned by the data.

  11. Investigation of Cumulative Fatigue Damage Through Sequential Low Cycle Fatigue and High Cycle Fatigue Cycling at High Temperature for a Type 316LN Stainless Steel: Life-Prediction Techniques and Associated Mechanisms

    Science.gov (United States)

    Sarkar, Aritra; Nagesha, A.; Parameswaran, P.; Sandhya, R.; Laha, K.; Okazaki, M.

    2017-01-01

    Cumulative fatigue damage under sequential low cycle fatigue (LCF) and high cycle fatigue (HCF) cycling was investigated at 923 K (650 °C) by conducting HCF tests on specimens subjected to prior LCF cycling at various strain amplitudes. Remnant HCF lives were found to decrease drastically with increase in prior fatigue exposure as a result of strong LCF-HCF interactions. The rate of decrease in remnant lives varied as a function of the applied strain amplitude. A threshold damage in terms of prior LCF life-fraction was found, below which no significant LCF-HCF interaction takes place. Similarly, a critical damage during the LCF pre-cycling marking the highest degree of LCF-HCF interaction was identified which was found to depend on the applied strain amplitude. In view of the non-linear damage accumulation behavior, Miner's linear damage rule proved to be highly non-conservative. Manson's damage curve approach, suitably modified, was found to be a better alternative for predicting the remnant HCF life. The single constant (β) employed in the model, which reflects the damage accumulation of the material under two/multi-level loading conditions is derived from the regression analysis of the experimental results and validated further.

  12. Endurance capacity and neuromuscular fatigue following high- vs moderate-intensity endurance training: A randomized trial.

    Science.gov (United States)

    O'Leary, T J; Collett, J; Howells, K; Morris, M G

    2017-02-16

    High-intensity exercise induces significant central and peripheral fatigue; however, the effect of endurance training on these mechanisms of fatigue is poorly understood. We compared the effect of cycling endurance training of disparate intensities on high-intensity exercise endurance capacity and the associated limiting central and peripheral fatigue mechanisms. Twenty adults were randomly assigned to 6 weeks of either high-intensity interval training (HIIT, 6-8×5 minutes at halfway between lactate threshold and maximal oxygen uptake [50%Δ]) or volume-matched moderate-intensity continuous training (CONT, ~60-80 minutes at 90% lactate threshold). Two time to exhaustion (TTE) trials at 50%Δ were completed pre- and post-training to assess endurance capacity; the two post-training trials were completed at the pretraining 50%Δ (same absolute intensity) and the "new" post-training 50%Δ (same relative intensity). Pre- and post-exercise responses to femoral nerve and motor cortex stimulation were examined to determine peripheral and central fatigue, respectively. HIIT resulted in greater increases in TTE at the same absolute and relative intensities as pre-training (148% and 43%, respectively) compared with CONT (38% and -4%, respectively) (P≤.019). Compared with pre-training, HIIT increased the level of potentiated quadriceps twitch reduction (-34% vs -43%, respectively, P=.023) and attenuated the level of voluntary activation reduction (-7% vs -3%, respectively, P=.047) following the TTE trial at the same relative intensity. There were no other training effects on neuromuscular fatigue development. This suggests that central fatigue resistance contributes to enhanced high-intensity exercise endurance capacity after HIIT by allowing greater performance to be extruded from the muscle. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  13. A Direct Method For Predicting The High-Cycle Fatigue Regime In SMAs: Application To Nitinol Stents

    Directory of Open Access Journals (Sweden)

    Colombé Pierre

    2015-01-01

    Full Text Available In fatigue design of metals, it is common practice to distinguish between high-cycle fatigue (occurring after 10000–100000 cycles and low-cycle fatigue. For elastic-plastic materials, there is an established correlation between fatigue and energy dissipation. In particular, high-cycle fatigue occurs when the energy dissipation remains bounded in time. Although the physical mechanisms in SMAs differ from plasticity, the hysteresis observed in the stress-strain response shows that some energy dissipation occurs, and it can be reasonably assumed that situations where the energy dissipation remains bounded is the most favorable for fatigue design. We present a direct method for determining if the energy dissipation in a SMA structure is bounded or not. That method relies only on elastic calculations, thus bypassing incremental nonlinear analysis. Moreover, only a partial knowledge of the loading (namely the extreme values is needed. Some results related to Nitinol stents are presented.

  14. A New High-Speed, High-Cycle, Gear-Tooth Bending Fatigue Test Capability

    Science.gov (United States)

    Stringer, David B.; Dykas, Brian D.; LaBerge, Kelsen E.; Zakrajsek, Andrew J.; Handschuh, Robert F.

    2011-01-01

    A new high-speed test capability for determining the high cycle bending-fatigue characteristics of gear teeth has been developed. Experiments were performed in the test facility using a standard spur gear test specimens designed for use in NASA Glenn s drive system test facilities. These tests varied in load condition and cycle-rate. The cycle-rate varied from 50 to 1000 Hz. The loads varied from high-stress, low-cycle loads to near infinite life conditions. Over 100 tests were conducted using AISI 9310 steel spur gear specimen. These results were then compared to previous data in the literature for correlation. Additionally, a cycle-rate sensitivity analysis was conducted by grouping the results according to cycle-rate and comparing the data sets. Methods used to study and verify load-path and facility dynamics are also discussed.

  15. A framework for organizing cancer-related variations from existing databases, publications and NGS data using a High-performance Integrated Virtual Environment (HIVE).

    Science.gov (United States)

    Wu, Tsung-Jung; Shamsaddini, Amirhossein; Pan, Yang; Smith, Krista; Crichton, Daniel J; Simonyan, Vahan; Mazumder, Raja

    2014-01-01

    Years of sequence feature curation by UniProtKB/Swiss-Prot, PIR-PSD, NCBI-CDD, RefSeq and other database biocurators has led to a rich repository of information on functional sites of genes and proteins. This information along with variation-related annotation can be used to scan human short sequence reads from next-generation sequencing (NGS) pipelines for presence of non-synonymous single-nucleotide variations (nsSNVs) that affect functional sites. This and similar workflows are becoming more important because thousands of NGS data sets are being made available through projects such as The Cancer Genome Atlas (TCGA), and researchers want to evaluate their biomarkers in genomic data. BioMuta, an integrated sequence feature database, provides a framework for automated and manual curation and integration of cancer-related sequence features so that they can be used in NGS analysis pipelines. Sequence feature information in BioMuta is collected from the Catalogue of Somatic Mutations in Cancer (COSMIC), ClinVar, UniProtKB and through biocuration of information available from publications. Additionally, nsSNVs identified through automated analysis of NGS data from TCGA are also included in the database. Because of the petabytes of data and information present in NGS primary repositories, a platform HIVE (High-performance Integrated Virtual Environment) for storing, analyzing, computing and curating NGS data and associated metadata has been developed. Using HIVE, 31 979 nsSNVs were identified in TCGA-derived NGS data from breast cancer patients. All variations identified through this process are stored in a Curated Short Read archive, and the nsSNVs from the tumor samples are included in BioMuta. Currently, BioMuta has 26 cancer types with 13 896 small-scale and 308 986 large-scale study-derived variations. Integration of variation data allows identifications of novel or common nsSNVs that can be prioritized in validation studies. Database URL: BioMuta: http

  16. The Effect of Moderate and High-Intensity Fatigue on Groundstroke Accuracy in Expert and Non-Expert Tennis Players

    OpenAIRE

    Mark Lyons; Yahya Al-Nakeeb; Joanne Hankey; Alan Nevill

    2013-01-01

    peer-reviewed Exploring the effects of fatigue on skilled performance in tennis presents a significant challenge to the researcher with respect to ecological validity. This study examined the effects of moderate and high-intensity fatigue on groundstroke accuracy in expert and non-expert tennis players. The research also explored whether the effects of fatigue are the same regardless of gender and player's achievement motivation characteristics. 13 expert (7 male, 6 female) and 17 non-expe...

  17. A multi-temporal scale approach to high cycle fatigue simulation

    Science.gov (United States)

    Bhamare, Sagar; Eason, Thomas; Spottswood, Stephen; Mannava, Seetha R.; Vasudevan, Vijay K.; Qian, Dong

    2014-02-01

    High cycle fatigue (HCF) is a failure mechanism that dominates the life of many engineering components and structures. Time scale associated with HCF loading is a main challenge for developing a simulation based life prediction framework using conventional FEM approach. Motivated by these challenges, the extended space-time method (XTFEM) based on the time discontinuous Galerkin formulation is proposed. For HCF life prediction, XTFEM is coupled with a two-scale continuum damage mechanics model for evaluating the fatigue damage accumulation. Direct numerical simulations of HCF are performed using the proposed methodology on a notched specimen of AISI 304L steel. It is shown the total fatigue life can be accurately predicted using the proposed simulation approach based on XTFEM. The presented computational framework can be extended for predicting the service and the residual life of structural components.

  18. Experimental evaluation of the fretting fatigue behavior of high-strength steel monostrands

    DEFF Research Database (Denmark)

    Winkler, Jan; Fischer, Gregor; Georgakis, Christos T.

    2013-01-01

    . Moreover, the paper provides relevant information about the monostrand bending stiffness and the extent of relative displacement between core and outer wires of the monostrand undergoing flexural deformations. The results presented herein are of special interest for the fatigue analysis of modern stay......In this paper, the fretting fatigue behavior of pretensioned high-strength steel monostrands is investigated. A method based on the digital image correlation (DIC) technique was used to quantify the relative movement between individual wires along the length of the monostrand. The experimental data...

  19. Fatigue experiments on hybrid welded connections made of very high strength steels

    NARCIS (Netherlands)

    Pijpers, R.J.M.; Kolstein, M.H.; Romeijn, A.; Bijlaard, F.S.K.

    2009-01-01

    In a fatigue loaded structure made of Very High Strength Steels (VHSS) absolute and relative stress variations will be higher compared to those in structures made of lower grade steels. Stress concentrations in joints reduce the advantage of VHSS under cyclic loading. A hybrid connection, consisting

  20. Fatigue resistance of welded joints in aluminium high-speed craft: A total stress concept

    NARCIS (Netherlands)

    Den Besten, J.H.

    2015-01-01

    Crew transfers, surveillance duties and {security, rescue, interception} operations at sea typically require high-speed craft. Aluminium is quite often selected as hull structure material because of its weight save potential in comparison to steel. The fatigue strength, however, may become a point o

  1. Fatigue resistance of welded joints in aluminium high-speed craft: A total stress concept

    NARCIS (Netherlands)

    Den Besten, J.H.

    2015-01-01

    Crew transfers, surveillance duties and {security, rescue, interception} operations at sea typically require high-speed craft. Aluminium is quite often selected as hull structure material because of its weight save potential in comparison to steel. The fatigue strength, however, may become a point

  2. Fatigue strength of welded connections made of very high strength cast and rolled steels

    NARCIS (Netherlands)

    Pijpers, R.J.M.

    2011-01-01

    Although Very High Strength Steels (VHSS) with nominal strengths up to 1100 MPa have been available on the market for many years, the use of these steels in the civil engineering industry is still uncommon. The main objective of the research is the determination of the fatigue strength of welded con

  3. Effect of strain rate and temperature at high strains on fatigue behavior of SAP alloys

    DEFF Research Database (Denmark)

    Blucher, J.T.; Knudsen, Per; Grant, N.J.

    1968-01-01

    Fatigue behavior of three SAP alloys of two nominal compositions (7 and 13% Al2O3) was studied in terms of strain rate and temperature at high strains; strain rate had no effect on life at 80 F, but had increasingly greater effect with increasing temperature above 500 F; life decreased...

  4. Identification of low cycle fatigue parameters of high strength low-alloy (HSLA steel at room temperature

    Directory of Open Access Journals (Sweden)

    S. Bulatović

    2014-10-01

    Full Text Available Low cycle fatigue test was performed in ambient atmosphere at room temperature. Cycle loading of material, in case of High strength low-alloy steel, entails modifications of its properties and in this paper is therefore shown behavior of fatigue life using low cycle fatigue parameters. More precisely, crack initiation life of tested specimens was computed using theory of Coffin-Manson relation during the fatigue loading. The geometry of the stabilized hysteresis loop of welded joint HSLA steel, marked as Nionikral 70, is also analyzed. This stabilized hysteresis loop is very important for determination of materials properties.

  5. Coupling damage and reliability model of low-cycle fatigue and high energy impact based on the local stress-strain approach

    Institute of Scientific and Technical Information of China (English)

    Chen Hongxia; Chen Yunxia; Yang Zhou

    2014-01-01

    Fatigue induced products generally bear fatigue loads accompanied by impact processes, which reduces their reliable life rapidly. This paper introduces a reliability assessment model based on a local stress-strain approach considering both low-cycle fatigue and high energy impact loads. Two coupling relationships between fatigue and impact are given with effects of an impact process on fatigue damage and effects of fatigue damage on impact performance. The analysis of the former modifies the fatigue parameters and the Manson-Coffin equation for fatigue life based on material theories. On the other hand, the latter proposes the coupling variables and the difference of fracture toughness caused by accumulative fatigue damage. To form an overall reliability model including both fatigue failure and impact failure, a competing risk model is developed. A case study of an actuator cylinder is given to validate this method.

  6. Fatigue and gene expression in human leukocytes: increased NF-κB and decreased glucocorticoid signaling in breast cancer survivors with persistent fatigue.

    Science.gov (United States)

    Bower, Julienne E; Ganz, Patricia A; Irwin, Michael R; Arevalo, Jesusa M G; Cole, Steve W

    2011-01-01

    Fatigue is highly prevalent in the general population and is one of the most common side effects of cancer treatment. There is growing evidence that pro-inflammatory cytokines play a role in cancer-related fatigue, although the molecular mechanisms for chronic inflammation and fatigue have not been determined. The current study utilized genome-wide expression microarrays to identify differences in gene expression and associated alterations in transcriptional activity in leukocytes from breast cancer survivors with persistent fatigue (n=11) and non-fatigued controls (n=10). We focused on transcription of inflammation-related genes, particularly those responsive to the pro-inflammatory NF-κB transcription control pathway. Further, given the role of glucocorticoids as key regulators of inflammatory processes, we examined transcription of glucocorticoid-responsive genes indicative of potential glucocorticoid receptor (GR) desensitization. Plasma levels of cortisol were also assessed. Consistent with hypotheses, results showed increased expression of transcripts with response elements for NF-κB, and reduced expression of transcripts with response elements for glucocorticoids (p<.05) in fatigued breast cancer survivors. No differences in plasma levels of cortisol were observed. These data indicate that increased activity of pro-inflammatory transcription factors may contribute to persistent cancer-related fatigue and provide insight into potential mechanisms for tonic increases in NF-κB activity, specifically decreased expression of GR anti-inflammatory transcription factors.

  7. Functional and structural fatigue of titanium tantalum high temperature shape memory alloys (HT SMAs)

    Energy Technology Data Exchange (ETDEWEB)

    Niendorf, T., E-mail: Thomas.Niendorf@iwt.tu-freiberg.de [Institute of Materials Engineering, Technische Universität Bergakademie Freiberg, 09599 Freiberg (Germany); Krooß, P. [Lehrstuhl für Werkstoffkunde (Materials Science), University of Paderborn, 33098 Paderborn (Germany); Batyrsina, E. [Institut für Werkstoffkunde (Materials Science), Leibniz Universität Hannover, 30823 Garbsen (Germany); Paulsen, A.; Motemani, Y.; Ludwig, A.; Buenconsejo, P.; Frenzel, J.; Eggeler, G. [Institut für Werkstoffe, Ruhr-Universität Bochum, 44801 Bochum (Germany); Maier, H.J. [Institut für Werkstoffkunde (Materials Science), Leibniz Universität Hannover, 30823 Garbsen (Germany)

    2015-01-03

    Due to their high work output and good mechanical properties, actuators made from shape memory alloys (SMAs) are used in numerous applications. Unfortunately, SMAs such as nickel–titanium (Ni–Ti) can only be employed at temperatures up to about 100 °C. Lately, high-temperature shape memory alloys (HT SMAs) have been introduced to overcome this limitation. Ternary systems based on Ni–Ti have been intensively characterized and alloys are available that can operate at elevated temperatures. However, these alloys either contain substantial amounts of expensive noble elements like platinum and palladium, or the materials are brittle. The titanium–tantalum (Ti–Ta) system has been developed to overcome these issues. Binary Ti–Ta provides relatively high M{sub S} temperature combined with excellent workability, but it suffers from fast cyclic degradation. By alloying with third elements this drawback can be overcome: The ternary Ti–Ta–Al alloy shows overall promising properties as will be shown in the present work. In-situ thermo-mechanical cycling experiments were conducted and allowed for evaluation of the factors affecting the functional and structural fatigue of this alloy. Functional fatigue is dominated by ω-phase evolution, while structural fatigue is triggered by an interplay of ω-phase induced embrittlement and deformation constraints imposed by unsuitable texture. In addition, a concept for fatigue life extension proposed very recently for binary Ti–Ta, is demonstrated to be also applicable for the ternary Ti–Ta–Al.

  8. Molecular epidemiology, cancer-related symptoms, and cytokines pathway.

    Science.gov (United States)

    Reyes-Gibby, Cielito C; Wu, Xifeng; Spitz, Margaret; Kurzrock, Razelle; Fisch, Michael; Bruera, Eduardo; Shete, Sanjay

    2008-08-01

    The Human Genome Project and HapMap have led to a better appreciation of the importance of common genetic variation in determining cancer risk, created potential for predicting response to therapy, and made possible the development of targeted prevention and therapeutic interventions. Advances in molecular epidemiology can be used to explore the role of genetic variation in modulating the risk for severe and persistent symptoms, such as pain, depression, and fatigue, in patients with cancer. The same genes that are implicated in cancer risk might also be involved in the modulation of therapeutic outcomes. For example, polymorphisms in several cytokine genes are potential markers for genetic susceptibility both for cancer risk and for cancer-related symptoms. These genetic polymorphisms are stable markers and easily and reliably assayed to explore the extent to which genetic variation might prove useful in identifying patients with cancer at high-risk of symptom development. Likewise, they could identify subgroups who might benefit most from symptom intervention, and contribute to developing personalized and more effective therapies for persistent symptoms.

  9. Exercise Helps Counter Cancer-Linked Fatigue

    Science.gov (United States)

    ... similarly positive results, as did treatments that integrated exercise with mental health efforts. The team concluded that when it came to controlling cancer-related fatigue, the exercise and/or psychological therapy approaches appeared to outperform ...

  10. Corrosion Fatigue of High-Strength Titanium Alloys Under Different Stress Gradients

    Science.gov (United States)

    Baragetti, Sergio; Villa, Francesco

    2015-05-01

    Ti-6Al-4V is the most widely used high strength-to-mass ratio titanium alloy for advanced engineering components. Its adoption in the aerospace, maritime, automotive, and biomedical sectors is encouraged when highly stressed components with severe fatigue loading are designed. The extents of its applications expose the alloy to several aggressive environments, which can compromise its brilliant mechanical characteristics, leading to potentially catastrophic failures. Ti-6Al-4V stress-corrosion cracking and corrosion-fatigue sensitivity has been known since the material testing for pressurized tanks for Apollo missions, although detailed investigations on the effects of harsh environment in terms of maximum stress reduction have been not carried out until recent times. In the current work, recent experimental results from the authors' research group are presented, quantifying the effects of aggressive environments on Ti-6Al-4V under fatigue loading in terms of maximum stress reduction. R = 0.1 axial fatigue results in laboratory air, 3.5 wt.% NaCl solution, and CH3OH methanol solution at different concentrations are obtained for mild notched specimens ( K t = 1.18) at 2e5 cycles. R = 0.1 tests are also conducted in laboratory air, inert environment, 3.5 wt.% NaCl solution for smooth, mild and sharp notched specimens, with K t ranging from 1 to 18.65, highlighting the environmental effects for the different load conditions induced by the specimen geometry.

  11. HIGH CYCLE FATIGUE RELIABILITY ANALYSIS ON ROTOR HUB BASED ON APPROXIMATION TECHNIQUE

    Institute of Scientific and Technical Information of China (English)

    姜年朝; 周光明; 张逊; 戴勇; 倪俊; 张志清

    2013-01-01

    A high cycle fatigue reliability analysis approach to helicopter rotor hub is proposed under working load spectrum .Automatic calculation for the approach is implemented through writing the calculating programs .In the system ,the modification of geometric model of rotor hub is controlled by several parameters ,and finite element method and S-N curve method are then employed to solve the fatigue life by automatically assigned parameters .A database between assigned parameters and fatigue life is obtained via Latin Hypercube Sampling (LHS) on toler-ance zone of rotor hub .Different data-fitting technologies are used and compared to determine a highest-precision approximation for this database .The parameters are assumed to be independent of each other and follow normal distributions .Fatigue reliability is then computed by the Monte Carlo (MC) method and the mean-value first order second moment (M FOSM ) method .Results show that the approach has high efficiency and precision ,and is suit-able for engineering application .

  12. Is There a Progressive Withdrawal of Physiological Protections against High-Intensity Exercise-Induced Fatigue during Puberty?

    Directory of Open Access Journals (Sweden)

    Sébastien Ratel

    2015-12-01

    Full Text Available Puberty is characterized by a large number of physiological modifications that translate into increased neuromuscular fatigue during high-intensity exercise in adolescents compared to prepubertal children. This greater neuromuscular fatigue in adolescents could be attributed to peripheral (i.e., muscular and central (i.e., nervous factors that change through puberty. Among the peripheral changes are muscle mass, fiber type composition, energy metabolism and musculo-tendinous stiffness. Among the central modifications are the voluntary activation level, the antagonist co-activation and a differential interplay between central and peripheral fatigue. The objective of this review article will be to underline the importance of these factors on the development of neuromuscular fatigue during high-intensity exercise throughout puberty and to highlight that the adolescents could be physiologically less protected against fatiguing high-intensity exercise than their prepubertal counterparts.

  13. Computational simulation of probabilistic lifetime strength for aerospace materials subjected to high temperature, mechanical fatigue, creep and thermal fatigue

    Science.gov (United States)

    Boyce, Lola; Bast, Callie C.; Trimble, Greg A.

    1992-01-01

    This report presents the results of a fourth year effort of a research program, conducted for NASA-LeRC by the University of Texas at San Antonio (UTSA). The research included on-going development of methodology that provides probabilistic lifetime strength of aerospace materials via computational simulation. A probabilistic material strength degradation model, in the form of a randomized multifactor interaction equation, is postulated for strength degradation of structural components of aerospace propulsion systems subject to a number of effects or primitive variables. These primitive variables may include high temperature, fatigue or creep. In most cases, strength is reduced as a result of the action of a variable. This multifactor interaction strength degradation equation has been randomized and is included in the computer program, PROMISS. Also included in the research is the development of methodology to calibrate the above-described constitutive equation using actual experimental materials data together with regression analysis of that data, thereby predicting values for the empirical material constants for each effect or primitive variable. This regression methodology is included in the computer program, PROMISC. Actual experimental materials data were obtained from industry and the open literature for materials typically for applications in aerospace propulsion system components. Material data for Inconel 718 has been analyzed using the developed methodology.

  14. Variable amplitude corrosion fatigue and fracture mechanics of weldable high strength jack-up steels

    Science.gov (United States)

    Etube, Linus Sone

    The tubular welded joints used in the construction of Offshore structures can experience millions of variable amplitude wave induced stress cycles during their operational life. Fatigue has been identified as the main cause of degradation of structural integrity in these structures. As a result, fatigue is an important consideration in their design. Jack-up legs are made from a range of high strength steels with yield strengths up to TOOMPa. These steels are thought to exhibit fatigue resistance properties which are different when compared with conventional fixed platform steels such as BS 4360 50D and BS 7191 355D. The difference in their behaviour was heightened by the discovery, in the late 80s and early 90s, of extensive cracking around the spud can regions of several Jack-ups operating in the North Sea. It was thought that these steels may be more susceptible to hydrogen cracking and embrittlement. There was the additional requirement to study their behaviour under realistic loading conditions typical of the North Sea environment. This thesis contains results of an investigation undertaken to assess the performance of a typical high strength weldable Jack-up steel under realistic loading and environmental conditions. Details of the methodology employed to develop a typical Jack-up Offshore Standard load History (JOSH) are presented. The factors which influence fatigue resistance of structural steels used in the construction of Jack-up structures are highlighted. The methods used to model the relevant factors for inclusion in JOSH are presented with particular emphasis on loading and structural response interaction. Results and details of experimental variable amplitude corrosion fatigue (VACF) tests conducted using JOSH are reported and discussed with respect to crack growth mechanisms in high strength weldable Jack-up steels. Different fracture mechanics models for VACF crack growth prediction are compared and an improved generalised methodology for fast

  15. 乳腺癌患者癌因性疲乏与不良反应的相关性及研究%Correlation study between cancer-related fa-tigue and chemotherapy-induced adverse effects in patients with breast cancer

    Institute of Scientific and Technical Information of China (English)

    赵树林; 张述耀; 朱志伟; 林丹霞; 庄珊珊; 杨钰贤; 江艺; 张盛奇; 方翎

    2014-01-01

    目的:研究常见乳腺癌患者癌因性疲乏与使用化疗药所致的不良反应的相关性.方法:选择100例乳腺癌患者,在化疗前后均按癌症疲乏量表(CFS)评价患者的乏力程度,建立CRF-ADR综合评价量表,并在化疗前后检测与疲乏可能相关的各种因素,包括人肿瘤坏死因子-α(TNF-α)、白介素1(IL-1)、转化生长因子-β1(TGF-β1)水平及人尿中17-羟皮质类固醇(17-OHCS)在化疗结束后记录化疗不良反应情况分成有不良反应组及无不良反应组,进行分组统计学检验及相关性分析,探讨分析乳腺癌癌因性疲乏与化疗药引起不良反应的相关性因素.结果:全组100例乳腺癌患者中乏力发生率90%.全组出现化疗后相关不良反应的共有18例,占总例数的18%.化疗后出现人血中TNF-α水平异常升高81例(81.0%),差异有统计学意义;化疗后出现IL-1水平异常升高68例(68%),差异有统计学意义;化疗后出现人尿中17-OHCS水平异常升高11例(11%),其中有8例出现化疗后相关不良反应,占不良反应人数的44.4%(8/18),差异有统计学意义(P=0.0007),TGF-β1水平异常升高4例,差异无统计学意义.结论:人TNF-α及IL-1与患者癌性疲乏有密切关系,而人尿中17-OHCS水平的异常升高可能是预测发生化疗后相关不良反应的重要监测指标.%AIM:To prospectively explore the relationship and its possible mechanism between cancer-related fatigue and chemo-therapy-induced adverse effects in patients with breast cancer. METHODS:One hundred patients with an array of cancers were recruited in a survey on general condition according to the Cancer Fatigue Scale (CFS)prior- and post-chemotherapy.A suit of fa-tigue-associated factors including TNF-α,IL-1,TGF-β1and 17-OHCS were detected and determined with subsequent statistical and relevance analysis based on

  16. Fatigue in high speed aluminium craft: Evaluating a design methodology for estimating the fatigue life using large scale tests and full scale trials

    NARCIS (Netherlands)

    Drummen, I.; Schiere, M.; Tuitman, J.T.

    2013-01-01

    Within the VOMAS project, a methodology has been developed to estimate the fatigue life of high-speed aluminium crafts. This paper presents the large scale test and full scale trials which were done to acquire data for evaluating the developed methodology and presents results of this evaluation. Dur

  17. INFLUENCE OF LASER CUTTING ON THE FATIGUE LIMIT OF TWO HIGH STRENGTH STEELS

    OpenAIRE

    Mateo García, Antonio Manuel; Fargas Ribas, Gemma; Calvo Muñoz, Jessica; Roa Rovira, Joan Josep

    2013-01-01

    Laser cutting is widely used in the metal industry, particularly when components of high strength steels sheets are produced. On the other hand, the roughness of cut - edges produced by laser differs from that obt ained by other methods, such as mechanical blank ing, and this fact influence s the fatigue performance. Moreover, thermal effects are another factor to consider. In the present investigation, specimens of two grades of high strength ...

  18. Monitoring of hidden fatigue crack growth in multi-layer aircraft structures using high frequency guided waves

    Science.gov (United States)

    Chan, H.; Masserey, B.; Fromme, P.

    2015-03-01

    Varying loading conditions of aircraft structures result in stress concentration at fastener holes, where multi-layered components are connected, potentially leading to the development of hidden fatigue cracks in inaccessible layers. High frequency guided waves propagating along the structure allow for the structural health monitoring (SHM) of such components, e.g., aircraft wings. Experimentally the required guided wave modes can be easily excited using standard ultrasonic wedge transducers. However, the sensitivity for the detection of small, potentially hidden, fatigue cracks has to be ascertained. The type of multi-layered model structure investigated consists of two adhesively bonded aluminum plate-strips with a sealant layer. Fatigue experiments were carried out and the growth of fatigue cracks at the fastener hole in one of the metallic layers was monitored optically during cyclic loading. The influence of the fatigue cracks of increasing size on the scattered guided wave field was evaluated. The sensitivity and repeatability of the high frequency guided wave modes to detect and monitor the fatigue crack growth was investigated, using both standard pulse-echo equipment and a laser interferometer. The potential for hidden fatigue crack growth monitoring at critical and difficult to access fastener locations from a stand-off distance was ascertained. The robustness of the methodology for practical in situ ultrasonic monitoring of fatigue crack growth is discussed.

  19. The Effect of Drive Signal Limiting on High Cycle Fatigue Life Analysis

    Science.gov (United States)

    Kihm, Frederic; Rizzi, Stephen A.

    2014-01-01

    It is common practice to assume a Gaussian distribution of both the input acceleration and the response when modeling random vibration tests. In the laboratory, however, shaker controllers often limit the drive signal to prevent high amplitude peaks. The high amplitudes may either be truncated at a given level (socalled brick wall limiting or abrupt clipping), or compressed (soft limiting), resulting in drive signals which are no longer Gaussian. The paper first introduces several methods for limiting a drive signal, including brick wall limiting and compression. The limited signal is then passed through a linear time-invariant system representing a device under test. High cycle fatigue life predictions are subsequently made using spectral fatigue and rainflow cycle counting schemes. The life predictions are compared with those obtained from unclipped input signals. Some guidelines are provided to help the test engineer decide how clipping should be applied under different test scenarios.

  20. Effect of dried-bonito broth on mental fatigue and mental task performance in subjects with a high fatigue score.

    Science.gov (United States)

    Kuroda, Motonaka; Ishizaki, Taichi; Maruyama, Tomoaki; Takatsuka, Yoji; Kuboki, Tomifusa

    2007-12-05

    Dried-bonito broth is commonly employed as a soup and sauce base in Japanese cuisine and is considered to be a nutritional supplement that promotes recovery from fatigue. Previous human trials suggest that the ingestion of dried-bonito broth improves several mood states; however, its effect on fatigue has not yet been clarified. The aim of this study was to clarify the effects of daily ingestion of dried-bonito broth on fatigue and cognitive parameters by a placebo-controlled double blind crossover trial. Forty-eight subjects with fatigue symptoms ingested the dried-bonito broth or a placebo solution every day for 4 weeks. Mood states were evaluated by the Profile of Mood States (POMS), and mental task performance was evaluated by the Uchida-Kraepelin psychodiagnostic (UKP) test. Fatigue and total mood disturbance (TMD) scores on the POMS test decreased significantly during the dried-bonito broth ingestion (p<0.05), but did not change significantly during placebo ingestion. The change in vigor score during dried-bonito broth ingestion was significantly higher than that during placebo ingestion at 2 weeks (p<0.05). The results of the UKP test indicate that the numbers of both total answers and correct answers significantly increased during dried-bonito broth ingestion (p<0.05), while no significant changes were observed in the placebo ingestion. These results suggest that the daily ingestion of dried-bonito broth may improve the mood states, may reduce mental fatigue and may increase performance on a simple calculation task.

  1. High cocoa polyphenol rich chocolate may reduce the burden of the symptoms in chronic fatigue syndrome

    Directory of Open Access Journals (Sweden)

    Mellor Duane D

    2010-11-01

    Full Text Available Abstract Background Chocolate is rich in flavonoids that have been shown to be of benefit in disparate conditions including cardiovascular disease and cancer. The effect of polyphenol rich chocolate in subjects with chronic fatigue syndrome (CFS has not been studied previously. Methods We conducted a double blinded, randomised, clinical pilot crossover study comparing high cocoa liquor/polyphenol rich chocolate (HCL/PR in comparison to simulated iso-calorific chocolate (cocoa liquor free/low polyphenols(CLF/LP on fatigue and residual function in subjects with chronic fatigue syndrome. Subjects with CFS having severe fatigue of at least 10 out of 11 on the Chalder Fatigue Scale were enrolled. Subjects had either 8 weeks of intervention in the form of HCL/PR or CLF/LP, with a 2 week wash out period followed by 8 weeks of intervention with the other chocolate. Results Ten subjects were enrolled in the study. The Chalder Fatigue Scale score improved significantly after 8 weeks of the HCL/PR chocolate arm [median (range Exact Sig. (2-tailed] [33 (25 - 38 vs. 21.5 (6 - 35 0.01], but that deteriorated significantly when subjects were given simulated iso-calorific chocolate (CLF/CP [ 28.5 (17 - 20 vs. 34.5 (13-26 0.03]. The residual function, as assessed by the London Handicap scale, also improved significantly after the HCL/PR arm [0.49 (0.33 - 0.62 vs. 0.64 (0.44 - 0.83 0.01] and deteriorated after iso-calorific chocolate [00.44 (0.43 - 0.68 vs. 0.36 (0.33 - 0.620.03]. Likewise the Hospital Anxiety and Depression score also improved after the HCL/PR arm, but deteriorated after CLF/CP. Mean weight remained unchanged throughout the trial. Conclusion This study suggests that HCL/PR chocolate may improve symptoms in subjects with chronic fatigue syndrome.

  2. Isothermal fatigue behavior and damage modeling of a high temperature woven PMC[Polymer Matrix Composite

    Energy Technology Data Exchange (ETDEWEB)

    Gyekenyesi, A.L.

    2000-01-01

    This study focuses on the fully reversed fatigue behavior exhibited by a carbon fiber/polyimide resin woven laminate at room and elevated temperatures. Nondestructive video edge view microscopy and destructive sectioning techniques were used to study the microscopic damage mechanisms that evolved. The elastic stiffness was monitored and recorded throughout the fatigue life of the coupon. In addition, residual compressive strength tests were conducted on fatigue coupons with various degrees of damage as quantified by stiffness reduction. Experimental results indicated that the monotonic tensile properties were only minimally influenced by temperature, while the monotonic compressive and fully reversed fatigue properties displayed greater reductions due to the elevated temperature. The stiffness degradation as a function of cycles, consisted of three stages; a short-lived high degradation period, a constant degradation rate segment covering the majority of the life, and a final stage demonstrating an increasing rate of degradation up to failure. Concerning the residual compressive strength tests at room and elevated temperatures, the elevated temperature coupons appeared much more sensitive to damage. At elevated temperatures, coupons experienced a much larger loss in compressive strength when compared to room temperature coupons with equivalent damage. The fatigue damage accumulation law proposed for the model incorporates a scalar representation for damage, but admits a multiaxial, anisotropic evolutionary law. The model predicts the current damage (as quantified by residual stiffness) and remnant life of a composite that has undergone a known load at temperature. The damage/life model is dependent on the applied multiaxial stress state as well as temperature. Comparisons between the model and data showed good predictive capabilities concerning stiffness degradation and cycles to failure.

  3. Low visual information-processing speed and attention are predictors of fatigue in elementary and junior high school students

    Directory of Open Access Journals (Sweden)

    Yamano Emi

    2011-06-01

    Full Text Available Abstract Background Fatigue is a common complaint among elementary and junior high school students, and is known to be associated with reduced academic performance. Recently, we demonstrated that fatigue was correlated with decreased cognitive function in these students. However, no studies have identified cognitive predictors of fatigue. Therefore, we attempted to determine independent cognitive predictors of fatigue in these students. Methods We performed a prospective cohort study. One hundred and forty-two elementary and junior high school students without fatigue participated. They completed a variety of paper-and-pencil tests, including list learning and list recall tests, kana pick-out test, semantic fluency test, figure copying test, digit span forward test, and symbol digit modalities test. The participants also completed computerized cognitive tests (tasks A to E on the modified advanced trail making test. These cognitive tests were used to evaluate motor- and information-processing speed, immediate and delayed memory function, auditory and visual attention, divided and switching attention, retrieval of learned material, and spatial construction. One year after the tests, a questionnaire about fatigue (Japanese version of the Chalder Fatigue Scale was administered to all the participants. Results After the follow-up period, we confirmed 40 cases of fatigue among 118 students. In multivariate logistic regression analyses adjusted for grades and gender, poorer performance on visual information-processing speed and attention tasks was associated with increased risk of fatigue. Conclusions Reduced visual information-processing speed and poor attention are independent predictors of fatigue in elementary and junior high school students.

  4. Fatigue-induced damage of high-strength steels

    Science.gov (United States)

    Shetulov, D. I.; Myl'nikov, V. V.

    2014-03-01

    The issues on the estimation of the surface damage of the products produced from high-strength alloys are considered. Mathematical relationships for a numerical calculation of the surface damage are given. The peculiarities of the evaluation of the surface damage are investigated, as applied to high-strength alloys.

  5. Nordic Walking, a therapeutic modality against cancer related fatigue

    OpenAIRE

    González Castro, Cristina

    2014-01-01

    Existe evidencia de que el ejercicio físico puede mejorar los síntomas de los pacientes y supervivientes de cáncer y en especial la fatiga relativa al cáncer (FRC). El Nordic Walking (NW) es una novedosa forma de ejercicio físico que presenta ventajas fisiológicas y psicológicas significativas respecto de la marcha normal. Este artículo propone el NW como tratamiento terapéutico alternativo contra la FRC. There is evidence that physical exercise can improve symptoms in cancer patients and ...

  6. Central fatigue of the first dorsal interosseous muscle during low-force and high-force sustained submaximal contractions.

    Science.gov (United States)

    Eichelberger, Tamara D; Bilodeau, Martin

    2007-09-01

    The aim of this study was to compare the extent of central fatigue in the first dorsal interosseous (FDI) muscle of healthy adults in low, moderate and high-force submaximal contractions. Nine healthy adults completed four experimental sessions where index finger abduction force was recorded during voluntary contractions and in response to brief trains (five pulses at 100 Hz) of electrical stimulation. The ability to maximally activate FDI under volition, or voluntary activation, and its change with sustained activity (central fatigue) was assessed using the twitch interpolation technique. The fatigue tasks consisted of continuous isometric index finger abduction contractions held until exhaustion at four target force levels: 30%, 45%, 60% and 75% of the maximal voluntary contraction. The main finding was the presence of central fatigue for the 30% task, but not for the three other fatigue tasks. The extent of central fatigue was also associated with changes in a measure reflecting the status of peripheral structures/mechanisms. It appears that central fatigue contributed to task failure for the lowest force fatigue task (30%), but not for the other (higher) contraction intensities.

  7. Aspects of high-cycle fatigue performance in a Ti-6Al-4V alloy

    Energy Technology Data Exchange (ETDEWEB)

    Boyce, B.L.; Campbell, J.P.; Roder, O.; Thompson, A.W.; Ritchie, R.O.

    1999-07-01

    Determination of critical levels of microstructural damage that can lead to fatigue crack propagation under high-cycle fatigue loading conditions is a major concern for the aircraft industry regarding structural integrity of turbine engine components. The cyclic frequencies characteristic of service loading spectra are extremely high and appear to require a damage-tolerant design approach. One idea for such an approach is to attempt to define a practical, appropriate crack-propagation threshold, {Delta}K{sub TH}. The present study identifies a practical lower-bound large-crack threshold under high-cycle fatigue conditions in a Ti-6 Al-4V blade alloy (with {approximately}60% primary {alpha} in a matrix of lamellar {alpha}+{beta}). The authors suggest that lower-bound thresholds can be determined by modifying standard large-crack propagation tests to simulate small-crack behavior. Modification techniques include high load-ratio testing under both constant-R and constant-K{sub max} conditions, performed at cyclic loading frequencies up to 1 kHz and R ratios up to 0.95. The results of these tests are compared to the near-threshold behavior of naturally-initiated small cracks, and to the crack initiation and early growth behavior of small cracks emanating from sites of simulated foreign object damage.

  8. Creep and creep-fatigue behavior of high chromium steel weldment

    Institute of Scientific and Technical Information of China (English)

    Yukio TAKAHASHI; Masaaki TABUCHI

    2011-01-01

    Manuscript received I December 2010; in revised form 9 March 2011Strength of welded joints of high chromium steels is one of the important concerns for fabricators and operators of ultra supercritical thermal power plants. A number of creep as well as creep-fatigue tests with tensile hold have been carried out on the welded joints of two types of high chromium steels widely used in Japan, I.e. Grade 91 and 122 steels. It was found that failure occurred in fine grain heat-affected zone in all the creep-fatigue tests, even at a relatively low temperature and fairly short time where failure occurred in plain base metal region in simple creep testing. Four procedures were used to predict failure lives and their results were compared with the test results. A newly proposed energy-based approach gave the best estimation of failure life, without respect of the material and temperature.

  9. Prediction of three-dimensional crack propagation paths taking high cycle fatigue into account

    Directory of Open Access Journals (Sweden)

    Guido Dhondt

    2016-01-01

    Full Text Available Engine components are usually subject to complex loading patterns such as mixed-mode Low Cycle Fatigue Loading due to maneuvering. In practice, this LCF Loading has to be superimposed by High Cyclic Fatigue Loading caused by vibrations. The changes brought along by HCF are twofold: first, the vibrational cycles which are superposed on the LCF mission increase the maximum loading of the mission and may alter the principal stress planes. Secondly, the HCF cycles themselves have to be evaluated on their own, assuring that no crack propagation occurs. Indeed, the vibrational frequency is usually so high that propagation leads to immediate failure. In the present paper it is explained how these two effects can be taken care of in a standard LCF crack propagation procedure. The method is illustrated by applying the Finite Element based crack propagation software CRACKTRACER3D on an engine blade.

  10. High cocoa polyphenol rich chocolate may reduce the burden of the symptoms in chronic fatigue syndrome

    OpenAIRE

    Mellor Duane D; Rigby Alan S; Beckett Stephen; Sathyapalan Thozhukat; Atkin Stephen L

    2010-01-01

    Abstract Background Chocolate is rich in flavonoids that have been shown to be of benefit in disparate conditions including cardiovascular disease and cancer. The effect of polyphenol rich chocolate in subjects with chronic fatigue syndrome (CFS) has not been studied previously. Methods We conducted a double blinded, randomised, clinical pilot crossover study comparing high cocoa liquor/polyphenol rich chocolate (HCL/PR) in comparison to simulated iso-calorific chocolate (cocoa liquor free/lo...

  11. Experimental investigation of high cycle thermal fatigue in a T-junction piping system

    Energy Technology Data Exchange (ETDEWEB)

    Selvam, P. Karthick; Kulenovic, Rudi; Laurien, Eckart [Stuttgart Univ. (Germany). Inst. of Nuclear Technology and Energy Systems (IKE)

    2015-10-15

    High cycle thermal fatigue damage of structure in the vicinity of T-junction piping systems in nuclear power plants is of importance. Mixing of coolant streams at significant temperature differences causes thermal fluctuations near piping wall leading to gradual thermal degradation. Flow mixing in a T-junction is performed. The determined factors result in bending stresses being imposed on the piping system ('Banana effect').

  12. Female Performance Under High-G During Fatigue and After G-Layoff.

    Science.gov (United States)

    1996-07-01

    The effects of fatigue and G- layoff on performance during high-G are mostly unknown for the female population. This research was conducted in the...performance measures were recorded. Performance was re-evaluated after 24 hrs. of sleeplessness and after either 2 or 4 weeks of layoff . Neither male...sleepless. No differences in performance were found in either gender due to layoff , although some physiologic deconditioning was apparent. Women

  13. Chemokines in cancer related inflammation

    Energy Technology Data Exchange (ETDEWEB)

    Allavena, Paola; Germano, Giovanni; Marchesi, Federica [Department of Immunology and Inflammation, IRCCS Humanitas Clinical Institute, Via Manzoni 56, 20089, Rozzano, Milan (Italy); Mantovani, Alberto, E-mail: alberto.mantovani@humanitasresearch.it [Department of Immunology and Inflammation, IRCCS Humanitas Clinical Institute, Via Manzoni 56, 20089, Rozzano, Milan (Italy); Department of Translational Medicine, University of Milan (Italy)

    2011-03-10

    Chemokines are key players of the cancer-related inflammation. Chemokine ligands and receptors are downstream of genetic events that cause neoplastic transformation and are abundantly expressed in chronic inflammatory conditions which predispose to cancer. Components of the chemokine system affect multiple pathways of tumor progression including: leukocyte recruitment, neo-angiogenesis, tumor cell proliferation and survival, invasion and metastasis. Evidence in pre-clinical and clinical settings suggests that the chemokine system represents a valuable target for the development of innovative therapeutic strategies.

  14. Resolving the frustration of fatigue.

    Science.gov (United States)

    Harpham, W S

    1999-01-01

    Fatigue is a ubiquitous side effect of many cancer therapies. Nevertheless, after treatment is complete, many survivors continue to feel a profound tiredness that affects almost all aspects of life. Even after recovery, patients are often frustrated by their continuing need for extra rest. In this deeply personal, first-person account, a physician relates the various ways that cancer-related fatigue can affect family dynamics, job responsibilities, social interactions, finances, and intimacy. Clinicians can help by searching for treatable medical conditions, but also by taking cancer-related fatigue, and the frustrations it causes, seriously. Patients should be reassured that the fatigue they feel is real, and that by learning personal energy conservation, they should be able to improve their abilities to function, to socialize, to interact with others, and ultimately to adjust to a "new normal" baseline.

  15. How to deal with very high cycle fatigue (VHCF) effects in practical applications?

    Energy Technology Data Exchange (ETDEWEB)

    Bacher-Hoechst, Manfred; Issler, Stephan [Robert Bosch GmbH, Stuttgart (Germany). Corporate Research and Advance Engineering, Materials and Process Engineering Metals

    2012-07-01

    Fatigue designing of high-stressed engine components is a key factor for reliable power train systems in automotive industry. In this context load assumptions are very important since this is attended with a pre-designing of important machine elements. Load analyses are usually performed by using experimental methods since the accuracy of load simulations are often not precise enough. An example for VHCF problems occurs in modern high pressure pumps for gasoline direct injection systems, which have load spectra with a large amount of cycles up to 10{sup 9} including a very powerful shape of the spectra. At the same time it is necessary to consider the properties of fuels in service since they might affect the fatigue strength significantly. For example, ethanol-based gasoline fuels are used in a lot of countries worldwide and especially their additives may lead to significant corrosion fatigue effects. In addition, it is well known that material inclusions play an important role for the VHCF behaviour especially for high-strength steels. This paper deals with possibilities to avoid VHCF problems of components in service to maintain reliable systems. (orig.)

  16. Fatigue experiments on connections made of very high strength steels

    NARCIS (Netherlands)

    Pijpers, R.; Kolstein, H.; Bijlaard, F.

    2013-01-01

    An effective application of Very High Strength Steels (VHSS) can be expected in truss-like structures, typically made of hollow sections. Improved design of VHSS truss structures could incorporate the application of cast joints, since an appropriate design of cast joints limits the stress concentrat

  17. Effect of pulsed current welding on fatigue behaviour of high strength aluminium alloy joints

    Energy Technology Data Exchange (ETDEWEB)

    Balasubramanian, V. [Department of Manufacturing Engineering, Annamalai University, Annamalai Nagar 608 002, Tamil Nadu (India)], E-mail: visvabalu@yahoo.com; Ravisankar, V. [Department of Manufacturing Engineering, Annamalai University, Annamalai Nagar 608 002, Tamil Nadu (India); Madhusudhan Reddy, G. [Metal Joining Section, Defence Metallurgical Research Laboratory (DMRL), Kanchanbag (P.O), Hyderabad 560 058 (India)

    2008-07-01

    High strength aluminium alloys (Al-Zn-Mg-Cu alloys) have gathered wide acceptance in the fabrication of light weight structures requiring high strength-to weight ratio, such as transportable bridge girders, military vehicles, road tankers and railway transport systems. The preferred welding processes of high strength aluminium alloy are frequently gas tungsten arc welding (GTAW) process and gas metal arc welding (GMAW) process due to their comparatively easier applicability and better economy. Weld fusion zones typically exhibit coarse columnar grains because of the prevailing thermal conditions during weld metal solidification. This often results inferior weld mechanical properties and poor resistance to hot cracking. In this investigation, an attempt has been made to refine the fusion zone grains by applying pulsed current welding technique. Rolled plates of 6 mm thickness have been used as the base material for preparing single pass welded joints. Single V butt joint configuration has been prepared for joining the plates. The filler metal used for joining the plates is AA 5356 (Al-5Mg (wt%)) grade aluminium alloy. Four different welding techniques have been used to fabricate the joints and they are: (i) continuous current GTAW (CCGTAW), (ii) pulsed current GTAW (PCGTAW), (iii) continuous current GMAW (CCGMAW) and (iv) pulsed current GMAW (PCGMAW) processes. Argon (99.99% pure) has been used as the shielding gas. Fatigue properties of the welded joints have been evaluated by conducting fatigue test using rotary bending fatigue testing machine. Current pulsing leads to relatively finer and more equi-axed grain structure in gas tungsten arc (GTA) and gas metal arc (GMA) welds. In contrast, conventional continuous current welding resulted in predominantly columnar grain structures. Grain refinement is accompanied by an increase in fatigue life and endurance limit.

  18. Microstructure-Sensitive Modeling of High Cycle Fatigue (Preprint)

    Science.gov (United States)

    2009-03-01

    history ( carburization and shot peening) and resulting residual stresses are considered in the case of subsurface crack formation at primary inclusions...experimental responses for known microstructures. Effects of process history ( carburization and shot peening) and resulting residual stresses are considered...nonmetallic inclusions. 3. HCF Crack Formation in Carburized and Shot Peened Martensitic Gear Steel High strength low carbon martensitic gear steel is a

  19. Metallurgical instabilities during the high temperature low cycle fatigue of nickel-base superalloys

    Science.gov (United States)

    Antolovich, S. D.; Jayaraman, N.

    1983-01-01

    An investigation is made of the microstructural instabilities that affect the high temperature low cycle fatigue (LCF) life of nickel-base superalloys. Crack initiation processes, provoked by the formation of carbides and the coarsening of the grains of the material at high temperatures are discussed. Experimental results are examined, and it is concluded that LCF behavior can be understood more fully only if details of the material and its dynamic behavior at high temperatures are considered. The effects of high stress, dislocation debris, and increasing environmental damage on the life of the alloy are discussed.

  20. Low cycle fatigue numerical estimation of a high pressure turbine disc for the AL-31F jet engine

    Directory of Open Access Journals (Sweden)

    Spodniak Miroslav

    2017-01-01

    Full Text Available This article deals with the description of an approximate numerical estimation approach of a low cycle fatigue of a high pressure turbine disc for the AL-31F turbofan jet engine. The numerical estimation is based on the finite element method carried out in the SolidWorks software. The low cycle fatigue assessment of a high pressure turbine disc was carried out on the basis of dimensional, shape and material disc characteristics, which are available for the particular high pressure engine turbine. The method described here enables relatively fast setting of economically feasible low cycle fatigue of the assessed high pressure turbine disc using a commercially available software. The numerical estimation of accuracy of a low cycle fatigue depends on the accuracy of required input data for the particular investigated object.

  1. Low cycle fatigue numerical estimation of a high pressure turbine disc for the AL-31F jet engine

    Science.gov (United States)

    Spodniak, Miroslav; Klimko, Marek; Hocko, Marián; Žitek, Pavel

    This article deals with the description of an approximate numerical estimation approach of a low cycle fatigue of a high pressure turbine disc for the AL-31F turbofan jet engine. The numerical estimation is based on the finite element method carried out in the SolidWorks software. The low cycle fatigue assessment of a high pressure turbine disc was carried out on the basis of dimensional, shape and material disc characteristics, which are available for the particular high pressure engine turbine. The method described here enables relatively fast setting of economically feasible low cycle fatigue of the assessed high pressure turbine disc using a commercially available software. The numerical estimation of accuracy of a low cycle fatigue depends on the accuracy of required input data for the particular investigated object.

  2. Study of stress ratio effect on titanium alloy fatigue under high-frequency loading

    Energy Technology Data Exchange (ETDEWEB)

    Voznyj, T.S.; Gurvich, Yu.V.; Kirillov, V.I.; Troyan, I.A. (AN Ukrainskoj SSR, Kiev. Inst. Problem Prochnosti)

    1983-02-01

    Endurance of two titanium alloys, OT4 type ..cap alpha..-alloy and VT6 martensite class, (..cap alpha..+..beta..)-alloy was studied under symmetric and asymmetric tension-compression at 10 kHz frequency and room temperature using a magnetostriction resonance device. The tests were carried out in the air without water cooling usual in high-frequency tests, since a very low hysteresis dissipation of energy was observed under cyclic loading near the fatigue limit of these titanium alloys. Fatigue curves are obtained on the basis of 10/sup 9/ cycles. The ratio is found for the endurance limit based on 10/sup 7/ and 10/sup 8/ cycles to the ultimate strength under symmetric loading. An equation is given which satisfactorily describes limiting amplitude diagrams, and its coefficients are analyzed.

  3. Prediction of lifetime in static fatigue at high temperatures for ceramic matrix composites

    Energy Technology Data Exchange (ETDEWEB)

    Loseille, O.; Lamon, J. [Univ Bordeaux, CNRS, Lab Thermostruct Composites, Bordeaux (France)

    2010-07-01

    Previous works have shown that ceramic matrix composites are sensitive to delayed failure during fatigue in oxidizing environments. The phenomenon of slow crack growth has been deeply investigated on single fibers and multi-filament tows in previous papers. The present paper proposes a multiscale model of failure driven by slow crack growth in fibers, for 2D woven composites under a constant load. The model is based on the delayed failure of longitudinal tows. Additional phenomena involved in the failure of tows have been identified using fractographic examination of 2D woven SiC/SiC composite test specimens after fatigue tests at high temperatures. Stochastic features including random load sharing, fiber overloading, fiber characteristics and fiber arrangement within the tows have been introduced using appropriate density functions. Rupture time predictions are compared to experimental data. (authors)

  4. A Simulation Method for High-Cycle Fatigue-Driven Delamination using a Cohesive Zone Model

    DEFF Research Database (Denmark)

    Bak, Brian Lau Verndal; Turon, A.; Lindgaard, Esben;

    2016-01-01

    on parameter fitting of any kind. The method has been implemented as a zero-thickness eight-node interface element for Abaqus and as a spring element for a simple finite element model in MATLAB. The method has been validated in simulations of mode I, mode II, and mixed-mode crack loading for both self......A novel computational method for simulating fatigue-driven mixed-mode delamination cracks in laminated structures under cyclic loading is presented. The proposed fatigue method is based on linking a cohesive zone model for quasi-static crack growth and a Paris' law-like model described......-similar and non-self-similar crack propagation. The method produces highly accurate results compared with currently available methods and is capable of simulating general mixed-mode non-self-similar crack growth problems....

  5. Fatigue failure of regenerator screens in a high frequency Stirling engine

    Science.gov (United States)

    Hull, David R.; Alger, Donald L.; Moore, Thomas J.; Scheuermann, Coulson M.

    1988-01-01

    Failure of Stirling Space Power Demonstrator Engine (SPDE) regenerator screens was investigated. After several hours of operation the SPDE was shut down for inspection and on removing the regenator screens, debris of unknown origin was discovered along with considerable cracking of the screens in localized areas. Metallurgical analysis of the debris determined it to be cracked-off-deformed pieces of the 41 micron thickness Type 304 stainless steel wire screen. Scanning electron microscopy of the cracked screens revealed failures occurring at wire crossovers and fatigue striations on the fracture surface of the wires. Thus, the screen failure can be characterized as a fatigue failure of the wires. The crossovers were determined to contain 30 percent reduction in wire thickness and a highly worked microstructure occurring from the manufacturing process of the wire screens. Later it was found that reduction in wire thickness occurred because the screen fabricator had subjected it to a light cold-roll process after weaving. Installation of this screen left a clearance in the regenerator allowing the screens to move. The combined effects of the reduction in wire thickness, stress concentration (caused by screen movement), and highly worked microstructure at the wire crossovers led to the fatigue failure of the screens.

  6. A surface crosslinked UHMWPE stabilized by vitamin E with low wear and high fatigue strength.

    Science.gov (United States)

    Oral, Ebru; Ghali, Bassem W; Rowell, Shannon L; Micheli, Brad R; Lozynsky, Andrew J; Muratoglu, Orhun K

    2010-09-01

    Wear particle-induced periprosthetic osteolysis has been a clinical problem driving the development of wear resistant ultrahigh molecular weight polyethylene (UHMWPE) for total joint replacement. Radiation crosslinking has been used to decrease wear through decreased plastic deformation; but crosslinking also reduces mechanical properties including fatigue resistance, a major factor limiting the longevity of joint implants. Reducing UHMWPE wear with minimal detriment to mechanical properties is an unaddressed need for articular bearing surface development. Here we report a novel approach to achieve this by limiting crosslinking to the articular surface. The antioxidant vitamin E reduces crosslinking efficiency in UHMWPE during irradiation with increasing concentration, thus we propose to spatially control the crosslink density distribution by controlling the vitamin E concentration profile. Surface crosslinking UHMWPE prepared using this approach had high wear resistance and decreased crosslinking in the bulk resulting in high fatigue crack propagation resistance. The interface region did not represent a weakness in the material due to the gradual change in the crosslink density. Such an implant has the potential of decreasing risk of fatigue fracture of total joint implants as well as expanding the use of UHMWPE to younger and more active patients.

  7. Highly sensitive detection of cancer-related genes based on complete fluorescence restoration of a molecular beacon with a functional overhang.

    Science.gov (United States)

    Li, Feng; Zhou, Ying-Ying; Peng, Ting; Xu, Huo; Zhang, Rong-Bo; Zhao, Hui; Wang, Zheng-Yong; Lv, Jian-Xin; Wu, Zai-Sheng; Shen, Zhi-Fa

    2016-07-21

    The accurate detection of cancer-related genes is of great significance for early diagnosis and targeted therapy of cancer. In this contribution, an automatically cycling operation of a functional overhang-containing molecular beacon (OMB)-based sensing system was proposed to perform amplification detection of the p53 gene. Contrary to the common molecular beacon (MB), a target DNA is designated to hybridize with a label-free recognition probe (RP) with a hairpin structure rather than OMB. In the presence of a target DNA of interest, the locked primer in RP opens and triggers the subsequent amplification procedures. The newly-developed OMB is not only capable of accomplishing cyclical nucleic acid strand-displacement polymerization (CNDP) with the help of polymerase and nicking endonuclease, but is also cleaved by restriction endonucleases, removing the quencher away from the fluorophore. Thus, the target DNA at an extremely low concentration is expected to generate a considerable amount of double-stranded and cleaved OMBs, and the quenched fluorescence is completely restored, leading to a dramatic increase in fluorescence intensity. Utilizing this sensing platform, the target gene can be detected down to 8.2 pM in a homogeneous way, and a linear response range of 0.01 to 150 nM could be obtained. More strikingly, the mutant genes can be easily distinguished from the wild-type ones. The proof-of-concept demonstrations reported herein are expected to promote the development of DNA biosensing systems, showing great potential in basic research and clinical diagnosis.

  8. Environmental degradation of 316 stainless steel in high temperature low cycle fatigue

    Science.gov (United States)

    Kalluri, Sreeramesh; Manson, S. Stanford; Halford, Gary R.

    1987-01-01

    Procedures based on modification of the conventional Strainrange Partitioning method are proposed to characterize the time-dependent degradation of engineering alloys in high-temperature, low-cycle fatigue. Creep-fatigue experiments were conducted in air using different waveforms of loading on 316 stainless steel at 816 C (1500 F) to determine the effect of exposure time on cyclic life. Reductions in the partitioned cyclic lives were observed with an increase in the time of exposure (or with the corresponding decrease in the steady-state creep rate) for all the waveforms involving creep strain. Excellent correlations of the experimental data were obtained by modifying the Conventional Strainrange Partitioning life relationships involving creep strain using a power-law term of either: (1) time of exposure, or (2) steady-state creep rate of the creep-fatigue test. Environmental degradation due to oxidation, material degradation due to the precipitation of carbides along the grain boundaries and detrimental deformation modes associated with the prolonged periods of creep were observed to be the main mechanisms responsible for life reductions at long exposure times.

  9. Influence of High Strength Steel Microstructure on Fatigue Crack Growth Rate

    Directory of Open Access Journals (Sweden)

    Enefola S. Ameh

    2016-07-01

    Full Text Available This study examines the effect of high strength steel microstructure morphology on fatigue crack growth rate (FCGR. To achieve this aim, three different heat treatment methods (normalizing, austempering quenching and tempering were considered and all the steel specimens were initially heated to 9500C austenization temperature for ninety minutes and then processed via the different heat treatment methods before viewing the resultant microstructures under light optical microscope (LOM. Fatigue crack growth rate tests were conducted on the resultant microstructures with compact tension specimens at room temperature as prescribed by American standard testing method E647. Results of FCGR tests showed normalized microstructure has the lowest FCGR (6.2698E-06, followed by quenched and tempered (7.9519E-06, asreceived (8.15E-06 and austempered (9.6667E-06 microstructure considering a low stress intensity factor range. The trend of results showed insignificant effect of microstructure over the Paris regime growth indicating fatigue crack growth rate is not a reliable parameter for correlating rate of crack propagation to microstructure

  10. Fretting fatigue behaviour of Ni-free high-nitrogen stainless steel in a simulated body fluid

    Directory of Open Access Journals (Sweden)

    Norio Maruyama, Sachiko Hiromoto, Eiji Akiyama and Morihiko Nakamura

    2013-01-01

    Full Text Available Fretting fatigue behaviour of Ni-free high-nitrogen steel (HNS with a yield strength of about 800 MPa, which was prepared by nitrogen gas pressurized electroslag remelting, was studied in air and in phosphate-buffered saline (PBS(-. For comparison, fretting fatigue behaviour of cold-rolled SUS316L steel (SUS316L(CR with similar yield strength was examined. The plain fatigue limit of HNS was slightly lower than that of SUS316L(CR although the former had a higher tensile strength than the latter. The fretting fatigue limit of HNS was higher than that of SUS316L(CR both in air and in PBS(-. A decrease in fatigue limit of HNS by fretting was significantly smaller than that of SUS316L(CR in both environments, indicating that HNS has better fretting fatigue resistance than SUS316L(CR. The decrease in fatigue limit by fretting is discussed taking into account the effect of friction stress due to fretting and the additional influences of wear, tribocorrosion and plastic deformation in the fretted area.

  11. High Cycle Fatigue Properties of Die-Cast Magnesium Alloy AZ91D with Addition of Different Concentrations of Cerium

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The effect of addition of different concentrations of Ce on high-cycle fatigue behavior of die-cast magnesium al-loy AZ91D was investigated. Mechanical fatigue tests were conducted at the stress ratio of R = 0.1, and fatigue strength was evaluated using up-and-down loading method. The results show that the grain size of AZ91D alloy is remarkably refined, and the amount of porosity decreases and evenly distributes with the addition of Ce. The fatigue strength of AZ91D alloy at room temperature increases from 96.7 up to 116.3 MPa (1% Ce) and 105.5 MPa (2% Ce), respectively, at the number of cycles to failure, Nf = 1 × 107. The fatigue crack of AZ91D alloy initiates at porosities and inclusions, and propagates along grain boundaries. The fatigue striations on fractured surface appear with Ce addition. The fatigue fracture surface of test specimens shows mixed-fracture characteristics of quasi-cleavage and dimple.

  12. Quadriceps and respiratory muscle fatigue following high-intensity cycling in COPD patients.

    Directory of Open Access Journals (Sweden)

    Damien Bachasson

    Full Text Available Exercise intolerance in COPD seems to combine abnormal ventilatory mechanics, impaired O2 transport and skeletal muscle dysfunction. However their relative contribution and their influence on symptoms reported by patients remain to be clarified. In order to clarify the complex interaction between ventilatory and neuromuscular exercise limiting factors and symptoms, we evaluated respiratory muscles and quadriceps contractile fatigue, dynamic hyperinflation and symptoms induced by exhaustive high-intensity cycling in COPD patients. Fifteen gold II-III COPD patients (age = 67 ± 6 yr; BMI = 26.6 ± 4.2 kg.m(-2 performed constant-load cycling test at 80% of their peak workload until exhaustion (9.3 ± 2.4 min. Before exercise and at exhaustion, potentiated twitch quadriceps strength (Q(tw, transdiaphragmatic (P(di,tw and gastric (P(ga,tw pressures were evoked by femoral nerve, cervical and thoracic magnetic stimulation, respectively. Changes in operational lung volumes during exercise were assessed via repetitive inspiratory capacity (IC measurements. Dyspnoea and leg discomfort were measured on visual analog scale. At exhaustion, Q(tw (-33 ± 15%, >15% reduction observed in all patients but two and Pdi,tw (-20 ± 15%, >15% reduction in 6 patients were significantly reduced (P15% reduction in 3 patients. Percentage reduction in Q(tw correlated with the percentage reduction in P(di,tw (r = 0.66; P<0.05. Percentage reductions in P(di,tw and P(ga,tw negatively correlated with the reduction in IC at exhaustion (r = -0.56 and r = -0.62, respectively; P<0.05. Neither dyspnea nor leg discomfort correlated with the amount of muscle fatigue. In conclusion, high-intensity exercise induces quadriceps, diaphragm and less frequently abdominal contractile fatigue in this group of COPD patients. In addition, the rise in end-expiratory lung volume and diaphragm flattening associated with dynamic hyperinflation in COPD might limit the development of abdominal and

  13. Effect of corrosion and sandblasting on the high cycle fatigue behavior of reinforcing B500C steel bars

    Directory of Open Access Journals (Sweden)

    Marina C. Vasco

    2017-10-01

    Full Text Available . In a series of applications, steel reinforced concrete structures are subjected to fatigue loads during their service life, what in most cases happens in corrosive environments. Surface treatments have been proved to represent proper processes in order to improve both fatigue and corrosion resistances. In this work, the effect of corrosion and sandblasting on the high cycle fatigue behavior reinforcing steel bars is investigated. The investigated material is the reinforcing steel bar of technical class B500C, of nominal diameter of 12 mm. Steel bars specimens were first exposed to corrosion in alternate salt spray environment for 30 and 60 days and subjected to both tensile and fatigue tests. Then, a series of specimens were subjected to common sandblasting, corroded and mechanically tested. Metallographic investigation and corrosion damage evaluation regarding mass loss and martensitic area reduction were performed. Tensile tests were conducted after each corrosion exposure period prior to the fatigue tests. Fatigue tests were performed at a stress ratio, R, of 0.1 and loading frequency of 20 Hz. All fatigue tests series as well as tensile test were also performed for as received steel bars to obtain the reference behavior. The results have shown that sandblasting hardly affects the tensile behavior of the uncorroded material. The effect of sandblasting on the tensile behavior of pre-corroded specimens seems to be also limited. On the other hand, fatigue results indicate an improved fatigue behavior for the sandblasted material after 60 days of corrosion exposure. Martensitic area reductions, mass loss and depth of the pits were significantly smaller for the case of sandblasted materials, which confirms an increased corrosion resistance

  14. Digital Micromirror Device (DMD-Based High-Cycle Torsional Fatigue Testing Micromachine for 1D Nanomaterials

    Directory of Open Access Journals (Sweden)

    Chenchen Jiang

    2016-03-01

    Full Text Available Fatigue behavior of nanomaterials could ultimately limit their applications in variable nano-devices and flexible nanoelectronics. However, very few existing nanoscale mechanical testing instruments were designed for dedicated fatigue experiments, especially for the challenging torsional cyclic loading. In this work, a novel high-cycle torsion straining micromachine, based on the digital micromirror device (DMD, has been developed for the torsional fatigue study on various one-dimensional (1D nanostructures, such as metallic and semiconductor nanowires. Due to the small footprint of the DMD chip itself and its cable-remote controlling mechanisms, it can be further used for the desired in situ testing under high-resolution optical or electron microscopes (e.g., scanning electron microscope (SEM, which allows real-time monitoring of the fatigue testing status and construction of useful structure-property relationships for the nanomaterials. We have then demonstrated its applications for testing nanowire samples with diameters about 100 nm and 500 nm, up to 1000 nm, and some of them experienced over hundreds of thousands of loading cycles before fatigue failure. Due to the commercial availability of the DMD and millions of micromirrors available on a single chip, this platform could offer a low-cost and high-throughput nanomechanical solution for the uncovered torsional fatigue behavior of various 1D nanostructures.

  15. Microstructural and Material Quality Effects on Rolling Contact Fatigue of Highly Elastic Intermetallic NiTi Ball Bearings

    Science.gov (United States)

    Dellacorte, Christopher; Howard, S. Adam; Thomas, Fransua; Stanford, Malcolm K.

    2017-01-01

    Rolling element bearings made from highly-elastic intermetallic materials (HIM)s, such as 60NiTi, are under development for applications that require superior corrosion and shock resistance. Compared to steel, intermetallics have been shown to have much lower rolling contact fatigue (RCF) stress capability in simplified 3-ball on rod (ASTM STP 771) fatigue tests. In the 3-ball tests, poor material quality and microstructural flaws negatively affect fatigue life but such relationships have not been established for full-scale 60NiTi bearings. In this paper, 3-ball-on-rod fatigue behavior of two quality grades of 60NiTi are compared to the fatigue life of full-scale 50mm bore ball bearings made from the same materials. 60NiTi RCF rods with material or microstructural flaws suffered from infant mortality failures at all tested stress levels while high quality 60NiTi rods exhibited no failures at lower stress levels. Similarly, tests of full-scale bearings made from flawed materials exhibited early surface fatigue and through crack type failures while bearings made from high quality material did not fail even in long-term tests. Though the full-scale bearing test data is yet preliminary, the results suggest that the simplified RCF test is a good qualitative predictor of bearing performance. These results provide guidance for materials development and to establish minimum quality levels required for successful bearing operation and life.

  16. Effect of cyclic high loading rates on the fatigue strength of aluminum-based composites

    Science.gov (United States)

    Calderon Arteaga, Hermes Eskander

    The study of fatigue under high loading rates is of great interest in the complete characterization of a new series of composites with Al-Cu-Mg matrix reinforced with AlB2 dispersoids. Homogeneous and functionally graded composites were prepared via gravity and centrifugal casting, respectively. Through centrifugal casting a gradual variation of the volume fraction of reinforcing particles along the cross section was obtained. In specific fabrication conditions, even complete segregation of the reinforcement particles was achieved. Charpy impact tests as well as hardness tests were conducted to assess the composite strength as a function of the weight percent of boron. The tensile properties of gravity cast samples were obtained. Then for both casting conditions, simple edge-notched bend SE(B) specimens were tested under fatigue conditions (three-point bending). The results from impact and hardness tests allowed identifying an interaction between the Mg dissolved in the matrix and the diborides. This interaction, which has never been reported before, was responsible for the strength reduction observed. It was assumed that a substitutional diffusion of Al by Mg atoms in the hp3 structure of diboride was causing the strength reduction, and three approaches were developed to estimate the amount of Mg depleted from the matrix by the diborides during the composite processing. Gravity cast samples were more sensitive to monotonic damage due to fatigue loads where compared with functionally-graded composites. Contrary to the centrifugal cast samples, gravity samples were also affected by the loading rate. The Mg-AlB2 interaction was also responsible for the reduction in the fatigue resistance as the weight percent of boron increased in both types of composites; regression models were obtained to predict the crack growth curve slope change as function of the boron level. The particle distribution showed to affect the crack growth behavior of the FGMs, decreasing the

  17. A model for life predictions of nickel-base superalloys in high-temperature low cycle fatigue

    Science.gov (United States)

    Romanoski, Glenn R.; Pelloux, Regis M.; Antolovich, Stephen D.

    1988-01-01

    Extensive characterization of low-cycle fatigue damage mechanisms was performed on polycrystalline Rene 80 and IN100 tested in the temperature range from 871 to 1000 C. Low-cycle fatigue life was found to be dominated by propagation of microcracks to a critical size governed by the maximum tensile stress. A model was developed which incorporates a threshold stress for crack extension, a stress-based crack growth expression, and a failure criterion. The mathematical equivalence between this mechanistically based model and the strain-life low-cycle fatigue law was demonstrated using cyclic stress-strain relationships. The model was shown to correlate the high-temperature low-cycle fatigue data of the different nickel-base superalloys considered in this study.

  18. Mental fatigue negatively influences manual dexterity and anticipation timing but not repeated high-intensity exercise performance in trained adults.

    Science.gov (United States)

    Duncan, Michael J; Fowler, Nicholas; George, Oliver; Joyce, Samuel; Hankey, Joanne

    2015-01-01

    This study examined the impact of a period of mental fatigue on manual dexterity, anticipation timing and repeated high intensity exercise performance. Using a randomised, repeated measures experimental design, eight physically trained adults (mean age = 24.8 ± 4.1 years) undertook a 40 minute vigilance task to elicit mental fatigue or a control condition followed by four repeated Wingate anaerobic performance tests. Pre, post fatigue/control and post each Wingate test, manual dexterity (Seconds), coincidence anticipation (absolute error) were assessed. A series of two (condition) by six (time) ways repeated measures ANOVAs indicated a significant condition by time interactions for manual dexterity time (p = 0.021) and absolute error (p = 0.028). Manual dexterity and coincidence anticipation were significantly poorer post mental fatigue compared with control. There were no significant differences in mean power between conditions or across trials (all p > 0.05).

  19. Fatigue fracture of high-strength Al-Zn-Mg-Cu alloy

    Institute of Scientific and Technical Information of China (English)

    JIAN Hai-gen; JIANG Feng; WEN Kang; JIANG Long; HUANG Hong-feng; WEI Li-li

    2009-01-01

    X-ray diffractometry(XRD), optical microscopy(OM), scanning electron microscopy(SEM) were used to study the fatigue fracture of the T7451 Al-Zn-Mg-Cu alloy (470 ℃, 60 min+115 ℃, 8 h+165 ℃, 16 h). The study reveals mainly the microscopic structure of the alloy in the process of crack formation and crack growth. The fatigue fracture is characterized by three zones: fatigue crack source zone, fatigue crack propagation zone and fatigue fracture zone. The fatigue damage preferably incubates at the fractured inclusion particles at or near (about 25 μm) the specimen free surfaces, and these brittle Fe-rich intermetallic inclusion particles are (7-10) μm×(11-14) μm in size. Some features such as "feather-like", "river and range" and boundary extrusions can be observed in the fatigue propagation zone, and in the fatigue fracture zone the surface is rough and uneven.

  20. Effects of Aerobic Exercise on Cancer-related Fatigue in Breast Cancer Patients Receiving Chemotherapy:A Meta-analysis%有氧运动对乳腺癌患者癌因性疲乏疗效的 Meta 分析

    Institute of Scientific and Technical Information of China (English)

    邹凌云; 杨柳; 何晓玲; 宋祎; 徐锦江

    2014-01-01

    Objective Studies show that aerobic exercise may receive cancer - related fatigue of breast cancer patients undergoing chemotherapy,but some with controversial results. This meta - analysis is aimed to explore the intervention effects of aerobic exercise on CRF in breast cancer patients receiving chemotherapy. Methods A literature search of PubMed,Embase, CISCOM,CINAHL,Google Scholar,CNKI and CBM databases was conducted on articles published before September 1st, 2013. STATA 12. 0 software was used for the meta - analysis. Crude standardized mean difference(SMD)and its 95% confidence interval(CI)were calculated,and according to the results the association of the two was assessed. Results Twelve cases were brought into the comparative studies with a total of 1 014 breast cancer patients receiving chemotherapy,including 522 patients in the aerobic exercise group(the intervention group)and 492 patients in the usual care group(the control group). The meta - a-nalysis results revealed that the RPFS scores of breast cancer patients in the intervention group were significantly lower than those in the control group〔SMD = - 0. 82,95% CI( - 1. 04, - 0. 60),P ﹤ 0. 001〕. However,there was no significant difference in FACIT - F scores between the intervention and control groups〔SMD = 0. 09,95% CI( - 0. 07,0. 25),P = 0. 224〕. Sub-group analysis by ethnicity indicated that there were significant differences in RPFS and FACIT - F scores between the intervention and control groups among Asian populations〔RPFS:SMD = - 1. 08,95% CI( - 1. 35, - 0. 82),P ﹤ 0. 001;FACIT - F:SMD = 1. 20,95% CI(0. 70,1. 71),P ﹤ 0. 001〕,but no significance among Caucasian populations(P ﹥ 0. 05). Conclu-sion The current meta - analysis indicates that aerobic exercise may improve cancer - related fatigue in breast cancer patients re-ceiving chemotherapy,especially among Asian populations.%目的:研究表明有氧运动可缓解乳腺癌患者因化疗引起的癌因性疲乏( CRF)

  1. 参芪扶正注射液联合甲地孕酮改善晚期恶性肿瘤患者癌因性疲乏的临床研究%Clinical study on the effect of Shenqifuzheng injection combined with megestrol acetate in improving cancer - related fatigue in patients with advanced cancer

    Institute of Scientific and Technical Information of China (English)

    刘志勇; 周建伟; 潘龙赐; 葛婷

    2016-01-01

    目的:探讨参芪扶正注射液联合甲地孕酮改善晚期恶性肿瘤患者癌因性疲乏的临床效果。方法选择恶性肿瘤患者60例为研究对象,随机分作两组,一组为中西药联合组(30例),另一组为西药组(30例),前者使用参芪扶正注射液联合甲地孕酮加对症支持治疗,后者予甲地孕酮加对症支持治疗,比较两组治疗后 Piper 评分、血红蛋白(Hb)、总 T 细胞(CD3+)、Th 细胞(CD3+ CD4+)比例、TNF -α和 TGF -β1的水平。结果治疗后两组在 Pipper 评分各项中得分相比,中西医联合组显著低于西药组( t =2.412~3.723,P =0.008~0.040)。治疗后中西医药联合组 Hb、总T 细胞(CD3+)、Th 细胞(CD3+ CD4+)比率显著高于治疗后的西药组( t =2.543~3.812,P =0.011~0.039)。治疗后中西医药联合组静脉血 TNF -α、TGF -β1的水平显著低于西药组( t =2.913,4.223,P =0.002,0.034)。结论参芪扶正注射液联合甲地孕酮改善晚期恶性肿瘤患者癌因性疲乏具有较好的治疗效果,其机制可能与提高总 T 细胞、Th 细胞比例,降低 TGF -β1、TNF -α等细胞因子水平有关。%Objective To explore the effect of Shenqifuzheng injection combined with megestrol acetate in improving the effect of cancer- related fatigue in patients with advanced cancer. Methods A total of 60 cases of cancer were collected and randomly divided into Chinese com-bined western medicine group and western medicine group,each with 30 cases. In Chinese combined western medicine group,patients were ad-ministrated with Shenqifuzheng injection combined with megestrol acetate plus symptomatic and supportive treatment. In western medicine group, patients were given with megestrol acetate plus symptomatic and supportive treatment. Piper scoring,level of hemoglobin(Hb),total number of T cells(CD3 + ),ratio of Th cells(CD3 + and CD4 + )and levels of TNF -

  2. HIGH-TEMPERATURE LOW CYCLE FATIGUE BEHAVIOR OFNICKEL BASE SUPERALLOY GH536

    Institute of Scientific and Technical Information of China (English)

    M. Zhao; L.Y. Xu; K.S. Zhang; B.Y. Yang

    2001-01-01

    Low cycle fatigue tests on nickel base superalloy GH536 were performed at 600. 700and 800°C. The strain-life and cyclic stress-strain relationship were given at various temperatures. The change in fatigue life behavior and fatigue parameters with temperature increasing was discussed. At low and intermediate total strain amplitudes,the fatigue life was found to decrease with increasing temperature.``

  3. Severe fatigue is highly prevalent in ALL rheumatic diseases : an international study

    NARCIS (Netherlands)

    Geenen, R.; Overman, C.L.; Da Silva, J.A.P.; Kool, M.B.

    2014-01-01

    Background Fatigue is a common, disabling, and difficult to manage problem in rheumatic diseases. Prevalence estimates of fatigue within various rheumatic disease groups vary considerably. Data on the relative prevalence of severe fatigue across multiple rheumatic diseases using a similar instrument

  4. Severe fatigue is highly prevalent in ALL rheumatic diseases : an international study

    NARCIS (Netherlands)

    Geenen, R.|info:eu-repo/dai/nl/087017571; Overman, C.L.|info:eu-repo/dai/nl/328198838; Da Silva, J.A.P.; Kool, M.B.|info:eu-repo/dai/nl/304828335

    Background Fatigue is a common, disabling, and difficult to manage problem in rheumatic diseases. Prevalence estimates of fatigue within various rheumatic disease groups vary considerably. Data on the relative prevalence of severe fatigue across multiple rheumatic diseases using a similar instrument

  5. Dynamic fatigue reliability of contact wires based on dynamic simulation of high-speed pantograph-catenary

    Science.gov (United States)

    Hu, Ping; Liang, Jie; Fan, Wenli

    2017-05-01

    This paper proposed a dynamic fatigue reliability method of contact wires based on dynamic simulation of high-speed pantograph-catenary. Firstly, the Weibull distribution was adopted to describe the fatigue life of contact wires so as to build the fatigue reliability model of contact wires. And then 10 finite element models of elastic chain type for contact networks were set up with the EN50367 parameter. Thereafter the stress time of the weakest unit on contact wires was calculated through the finite element simulation. Secondly, the mean value and amplitude of each stress cycle were calculated by means of rain flow counting method, and these values were put into the reliability model to draw the changing curve of the fatigue reliability of contact wires with time. The numerical example showed that the fatigue reliability of contact wires would be less than 0.98 when these wires were used for more than 10 years. The method provided in this paper can be used to estimate the fatigue reliability of contact wires more accurately, and it can be used as a reference for the reliability design of the catenary system and the formulation of preventive maintenance plans.

  6. Benefits of thread rolling process to the stress corrosion cracking and fatigue resistance of high strength fasteners

    Energy Technology Data Exchange (ETDEWEB)

    Kephart, A.R.; Hayden, S.Z.

    1993-05-01

    Stress corrosion cracking (SCC) behavior of cut (machined) vice thread rolled Alloy X-750 and Alloy 625 fasteners in a simulated high temperature primary water environment has been evaluated. SCC testing at 360 and 338C included 157 small and 40 large 60{degree} Vee thread studs. Thread rolled fasteners had improved resistance relative to cut fasteners. Tests of fatigue resistance in air at room temperature and both air and primary water at 315C were conducted on smaller studs with both cut and rolled threads. Results showed rolled threads can have significantly improved fatigue lives over those of cut threads in both air and primary water. Fasteners produced by two different thread rolling methods, in-feed (radial) and through-feed (axial), revealed similar SCC initiation test results. Testing of thread rolled fasteners revealed no significant SCC or fatigue growth of rolling induced thread crest laps typical of the thread rolling process. While fatigue resistance differed between the two rolled thread supplier`s studs, neither of the suppliers studs showed SCC initiation at exposure times beyond that of cut threads with SCC. In contrast to rolling at room temperature, warm rolled (427C) threads showed no improvement over cut threads in terms of fatigue resistance. The observed improved SCC and fatigue performance of rolled threads is postulated to be due to interactive factors, including beneficial residual stresses in critically stressed thread root region, reduction of plastic strains during loading and formation of favorable microstructure.

  7. Randomized Trial of a Social Networking Intervention for Cancer-Related Distress.

    Science.gov (United States)

    Owen, Jason E; O'Carroll Bantum, Erin; Pagano, Ian S; Stanton, Annette

    2017-02-27

    Web and mobile technologies appear to hold promise for delivering evidence-informed and evidence-based intervention to cancer survivors and others living with trauma and other psychological concerns. Health-space.net was developed as a comprehensive online social networking and coping skills training program for cancer survivors living with distress. The purpose of this study was to evaluate the effects of a 12-week social networking intervention on distress, depression, anxiety, vigor, and fatigue in cancer survivors reporting high levels of cancer-related distress. We recruited 347 participants from a local cancer registry and internet, and all were randomized to either a 12-week waiting list control group or to immediate access to the intervention. Intervention participants received secure access to the study website, which provided extensive social networking capabilities and coping skills training exercises facilitated by a professional facilitator. Across time, the prevalence of clinically significant depression symptoms declined from 67 to 34 % in both conditions. The health-space.net intervention had greater declines in fatigue than the waitlist control group, but the intervention did not improve outcomes for depression, trauma-related anxiety symptoms, or overall mood disturbance. For those with more severe levels of anxiety at baseline, greater engagement with the intervention was associated with higher levels of symptom reduction over time. The intervention resulted in small but significant effects on fatigue but not other primary or secondary outcomes. Results suggest that this social networking intervention may be most effective for those who have distress that is not associated with high levels of anxiety symptoms or very poor overall psychological functioning. The trial was registered with the ClinicalTrials.gov database ( ClinicalTrials.gov #NCT01976949).

  8. Expert consensus statement on diagnosis and treatment of cancer-related depressed mood state based on Chinese medicine

    OpenAIRE

    2015-01-01

    This consensus statement is organized into six parts: 1) Definitions: cancer-related depressed mood state is defined as a group of depressive symptoms, rather than major depressive disorder. Thus, “cancer-related depression” or “depressed mood state” is introduced as standard terminology and associated with the Chinese medicine concept of “yu zheng” (depression syndrome). 2) Pathogenesis: factors including psychological stress, cancer pain, cancer fatigue, sleep disorders, surgery trauma, che...

  9. Creep-fatigue interaction in delamination crack propagation of advanced CFRPs at high temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Uematsu, Y. [Osaka Univ., Suita, Osaka (Japan). Dept. of Mechanical Engineering and Systems; Kitamura, T.; Ohtani, R. [Kyoto Univ. (Japan). Dept. of Engineering Physics and Mechanics

    1997-12-31

    The objective of this study is to elucidate creep-fatigue interaction in Mode 1 delamination crack propagation of polymers reinforced by carbon fibers at high temperatures. The materials tested are two undirectionally reinforced laminates, AS4/PEEK (carbon fiber: AS4, matrix: poly-ether-ether-ketone) and T800H/PMR-15 (carbon fiber: T800H, matrix: polyimide). Crack propagation tests are conducted in cyclic loading conditions with and without hold(s) at maximum tension and zero load at 473 K for AS4/PEEK laminates and 573 K for T800H/PMR-15 laminates, respectively. In fatigue with high frequency, the crack propagation rate per unit cycle da/dN is correlated well with the stress intensity factor range {Delta}K. However, the crack propagation in AS4/PEEK laminates depends strongly on the load waveform, while that in T800H/PMR-15 laminates is independent of it. The crack propagation in AS4/PEEK laminates is accelerated by the tensile load hold due to the creep deformation of matrix and it is purely time-dependent. In the time-dependent crack propagation, the rate per unit time da/dt is correlated well with the stress intensity factor K at the hold. On the other hand, the time-dependent crack propagation is decelerated by the zero-load-hold because of the creep recovery of matrix.

  10. Laser High-Cycle Thermal Fatigue of Pulse Detonation Engine Combustor Materials Tested

    Science.gov (United States)

    Zhu, Dong-Ming; Fox, Dennis S.; Miller, Robert A.

    2001-01-01

    Pulse detonation engines (PDE's) have received increasing attention for future aerospace propulsion applications. Because the PDE is designed for a high-frequency, intermittent detonation combustion process, extremely high gas temperatures and pressures can be realized under the nearly constant-volume combustion environment. The PDE's can potentially achieve higher thermodynamic cycle efficiency and thrust density in comparison to traditional constant-pressure combustion gas turbine engines (ref. 1). However, the development of these engines requires robust design of the engine components that must endure harsh detonation environments. In particular, the detonation combustor chamber, which is designed to sustain and confine the detonation combustion process, will experience high pressure and temperature pulses with very short durations (refs. 2 and 3). Therefore, it is of great importance to evaluate PDE combustor materials and components under simulated engine temperatures and stress conditions in the laboratory. In this study, a high-cycle thermal fatigue test rig was established at the NASA Glenn Research Center using a 1.5-kW CO2 laser. The high-power laser, operating in the pulsed mode, can be controlled at various pulse energy levels and waveform distributions. The enhanced laser pulses can be used to mimic the time-dependent temperature and pressure waves encountered in a pulsed detonation engine. Under the enhanced laser pulse condition, a maximum 7.5-kW peak power with a duration of approximately 0.1 to 0.2 msec (a spike) can be achieved, followed by a plateau region that has about one-fifth of the maximum power level with several milliseconds duration. The laser thermal fatigue rig has also been developed to adopt flat and rotating tubular specimen configurations for the simulated engine tests. More sophisticated laser optic systems can be used to simulate the spatial distributions of the temperature and shock waves in the engine. Pulse laser high

  11. Assessment of mental fatigue during car driving by using high resolution EEG activity and neurophysiologic indices.

    Science.gov (United States)

    Borghini, G; Vecchiato, G; Toppi, J; Astolfi, L; Maglione, A; Isabella, R; Caltagirone, C; Kong, W; Wei, D; Zhou, Z; Polidori, L; Vitiello, S; Babiloni, F

    2012-01-01

    Driving tasks are vulnerable to the effects of sleep deprivation and mental fatigue, diminishing driver's ability to respond effectively to unusual or emergent situations. Physiological and brain activity analysis could help to understand how to provide useful feedback and alert signals to the drivers for avoiding car accidents. In this study we analyze the insurgence of mental fatigue or drowsiness during car driving in a simulated environment by using high resolution EEG techniques as well as neurophysiologic variables such as heart rate (HR) and eye blinks rate (EBR). Results suggest that it is possible to introduce a EEG-based cerebral workload index that it is sensitive to the mental efforts of the driver during drive tasks of different levels of difficulty. Workload index was based on the estimation of increase of EEG power spectra in the theta band over prefrontal areas and the simultaneous decrease of EEG power spectra over parietal areas in alpha band during difficult drive conditions. Such index could be used in a future to assess on-line the mental state of the driver during the drive task.

  12. Flaw assessment guide for high-temperature reactor components subject to creep-fatigue loading

    Energy Technology Data Exchange (ETDEWEB)

    Ainsworth, R.A. (Nuclear Electric PLC, Berkeley (UK). Berkeley Nuclear Labs.); Ruggles, M.B. (Oak Ridge National Lab., TN (USA)); Takahashi, Y. (Central Research Inst. of Electric Power Industry, Komae, Tokyo (Japan). Komae Research Lab.)

    1990-10-01

    A high-temperature flaw assessment procedure is described. This procedure is a result of a collaborative effort between Electric Power Research Institute in the United States, Central Research Institute of Electric Power Industry in Japan, and Nuclear Electric plc in the United Kingdom. The procedure addresses preexisting defects subject to creep-fatigue loading conditions. Laws employed to calculate the crack growth per cycle are defined in terms of fracture mechanics parameters and constants related to the component material. The crack-growth laws can be integrated to calculate the remaining life of a component or to predict the amount of crack extension in a given period. Fatigue and creep crack growth per cycle are calculated separately, and the total crack extension is taken as the simple sum of the two contributions. An interaction between the two propagation modes is accounted for in the material properties in the separate calculations. In producing the procedure, limitations of the approach have been identified. 25 refs., 1 fig.

  13. Modeling of fatigue crack induced nonlinear ultrasonics using a highly parallelized explicit local interaction simulation approach

    Science.gov (United States)

    Shen, Yanfeng; Cesnik, Carlos E. S.

    2016-04-01

    This paper presents a parallelized modeling technique for the efficient simulation of nonlinear ultrasonics introduced by the wave interaction with fatigue cracks. The elastodynamic wave equations with contact effects are formulated using an explicit Local Interaction Simulation Approach (LISA). The LISA formulation is extended to capture the contact-impact phenomena during the wave damage interaction based on the penalty method. A Coulomb friction model is integrated into the computation procedure to capture the stick-slip contact shear motion. The LISA procedure is coded using the Compute Unified Device Architecture (CUDA), which enables the highly parallelized supercomputing on powerful graphic cards. Both the explicit contact formulation and the parallel feature facilitates LISA's superb computational efficiency over the conventional finite element method (FEM). The theoretical formulations based on the penalty method is introduced and a guideline for the proper choice of the contact stiffness is given. The convergence behavior of the solution under various contact stiffness values is examined. A numerical benchmark problem is used to investigate the new LISA formulation and results are compared with a conventional contact finite element solution. Various nonlinear ultrasonic phenomena are successfully captured using this contact LISA formulation, including the generation of nonlinear higher harmonic responses. Nonlinear mode conversion of guided waves at fatigue cracks is also studied.

  14. High-throughput sequencing of plasma microRNA in chronic fatigue syndrome/myalgic encephalomyelitis.

    Directory of Open Access Journals (Sweden)

    Ekua W Brenu

    Full Text Available BACKGROUND: MicroRNAs (miRNAs are known to regulate many biological processes and their dysregulation has been associated with a variety of diseases including Chronic Fatigue Syndrome/Myalgic Encephalomyelitis (CFS/ME. The recent discovery of stable and reproducible miRNA in plasma has raised the possibility that circulating miRNAs may serve as novel diagnostic markers. The objective of this study was to determine the role of plasma miRNA in CFS/ME. RESULTS: Using Illumina high-throughput sequencing we identified 19 miRNAs that were differentially expressed in the plasma of CFS/ME patients in comparison to non-fatigued controls. Following RT-qPCR analysis, we were able to confirm the significant up-regulation of three miRNAs (hsa-miR-127-3p, hsa-miR-142-5p and hsa-miR-143-3p in the CFS/ME patients. CONCLUSION: Our study is the first to identify circulating miRNAs from CFS/ME patients and also to confirm three differentially expressed circulating miRNAs in CFS/ME patients, providing a basis for further study to find useful CFS/ME biomarkers.

  15. Fatigue crack propagation resistance of virgin and highly crosslinked, thermally treated ultra-high molecular weight polyethylene.

    Science.gov (United States)

    Gencur, Sara J; Rimnac, Clare M; Kurtz, Steven M

    2006-03-01

    To prolong the life of total joint replacements, highly crosslinked ultra-high molecular weight polyethylenes (UHMWPEs) have been introduced to improve the wear resistance of the articulating surfaces. However, there are concerns regarding the loss of ductility and potential loss in fatigue crack propagation (FCP) resistance. The objective of this study was to evaluate the effects of gamma radiation-induced crosslinking with two different post-irradiation thermal treatments on the FCP resistance of UHMWPE. Two highly crosslinked and one virgin UHMWPE treatment groups (ram-extruded, orthopedic grade, GUR 1050) were examined. For the two highly crosslinked treatment groups, UHMWPE rods were exposed to 100 kGy and then underwent post-irradiation thermal processing either above the melt temperature or below the melt temperature (2 h-150 degrees C, 110 degrees C). Compact tension specimens were cyclically loaded to failure and the fatigue crack growth rate, da/dN, vs. cyclic stress intensity factor, DeltaK, behavior was determined and compared between groups. Scanning electron microscopy was used to examine fracture surface characteristics. Crosslinking was found to decrease the ability of UHMWPE to resist crack inception and propagation under cyclic loading. The findings also suggested that annealing as a post-irradiation treatment may be somewhat less detrimental to FCP resistance of UHMWPE than remelting. Scanning electron microscopy examination of the fracture surfaces demonstrated that the virgin treatment group failed in a more ductile manner than the two highly crosslinked treatment groups.

  16. Effects of High-Intensity Blood Flow Restriction Exercise on Muscle Fatigue

    Directory of Open Access Journals (Sweden)

    Neto Gabriel R.

    2014-07-01

    Full Text Available Strength training combined with blood flow restriction (BFR have been used to improve the levels of muscle adaptation. The aim of this paper was to investigate the acute effect of high intensity squats with and without blood flow restriction on muscular fatigue levels. Twelve athletes (aged 25.95 ± 0.84 years were randomized into two groups: without Blood Flow Restriction (NFR, n = 6 and With Blood Flow Restriction (WFR, n = 6 that performed a series of free weight squats with 80% 1-RM until concentric failure. The strength of the quadriceps extensors was assessed in a maximum voluntary isometric contraction integrated to signals from the surface electromyogram. The average frequency showed significant reductions in the WFR group for the vastus lateralis and vastus medialis muscles, and intergroup only for the vastus medialis. In conclusion, a set of squats at high intensity with BFR could compromise muscle strength immediately after exercise, however, differences were not significant between groups.

  17. Oxidation and the Effects of High Temperature Exposures on Notched Fatigue Life of an Advanced Powder Metallurgy Disk Superalloy

    Science.gov (United States)

    Sudbrack, Chantal K.; Draper, Susan L.; Gorman, Timothy T.; Telesman, Jack; Gab, Timothy P.; Hull, David R.

    2012-01-01

    Oxidation and the effects of high temperature exposures on notched fatigue life were considered for a powder metallurgy processed supersolvus heat-treated ME3 disk superalloy. The isothermal static oxidation response at 704 C, 760 C, and 815 C was consistent with other chromia forming nickel-based superalloys: a TiO2-Cr2O3 external oxide formed with a branched Al2O3 internal subscale that extended into a recrystallized - dissolution layer. These surface changes can potentially impact disk durability, making layer growth rates important. Growth of the external scales and dissolution layers followed a cubic rate law, while Al2O3 subscales followed a parabolic rate law. Cr- rich M23C6 carbides at the grain boundaries dissolved to help sustain Cr2O3 growth to depths about 12 times thicker than the scale. The effect of prior exposures was examined through notched low cycle fatigue tests performed to failure in air at 704 C. Prior exposures led to pronounced debits of up to 99 % in fatigue life, where fatigue life decreased inversely with exposure time. Exposures that produced roughly equivalent 1 m thick external scales at the various isotherms showed statistically equivalent fatigue lives, establishing that surface damage drives fatigue debit, not exposure temperature. Fractographic evaluation indicated the failure mode for the pre-exposed specimens involved surface crack initiations that shifted with exposure from predominately single intergranular initiations with transgranular propagation to multi-initiations from the cracked external oxide with intergranular propagation. Weakened grain boundaries at the surface resulting from the M23C6 carbide dissolution are partially responsible for the intergranular cracking. Removing the scale and subscale while leaving a layer where M23C6 carbides were dissolved did not lead to a significant fatigue life improvement, however, also removing the M23C6 carbide dissolution layer led to nearly full recovery of life, with a

  18. High-Cycle Fatigue Resistance of Si-Mo Ductile Cast Iron as Affected by Temperature and Strain Rate

    Science.gov (United States)

    Matteis, Paolo; Scavino, Giorgio; Castello, Alessandro; Firrao, Donato

    2015-09-01

    Silicon-molybdenum ductile cast irons are used to fabricate exhaust manifolds of internal combustion engines of large series cars, where the maximum pointwise temperature at full engine load may be higher than 973 K (700 °C). In this application, high-temperature oxidation and thermo-mechanical fatigue (the latter being caused by the engine start and stop and by the variation of its power output) have been the subject of several studies and are well known, whereas little attention has been devoted to the high-cycle fatigue, arising from the engine vibration. Therefore, the mechanical behavior of Si-Mo cast iron is studied here by means of stress-life fatigue tests up to 10 million cycles, at temperatures gradually increasing up to 973 K (700 °C). The mechanical characterization is completed by tensile and compressive tests and ensuing fractographic examinations; the mechanical test results are correlated with the cast iron microstructure and heat treatment.

  19. Effect of a high intensity quadriceps fatigue protocol on knee joint mechanics and muscle activation during gait in young adults.

    Science.gov (United States)

    Murdock, Gillian Hatfield; Hubley-Kozey, Cheryl L

    2012-02-01

    The purpose of this study was to determine the effect of impaired quadriceps function on knee joint biomechanics and neuromuscular function during gait. Surface electromyograms, three-dimensional motion and ground reaction forces were collected during gait before and after 20 healthy adults completed a high intensity quadriceps fatigue protocol. Pattern recognition techniques were utilized to examine changes in amplitude and temporal characteristics of all gait variables. The fatigue protocol resulted in decreased knee extensor torque generation and quadriceps median power frequencies for 18 of 20 participants (p gait data from these 18 participants was analyzed. The knee external rotation angle increased (p knee motion and loading characteristics were altered following a high intensity fatigue protocol in a manner that may place the knee joint at greater risk for joint pathology and injury.

  20. Effects of friction and high torque on fatigue crack propagation in Mode III

    Science.gov (United States)

    Nayeb-Hashemi, H.; McClintock, F. A.; Ritchie, R. O.

    1982-12-01

    Turbo-generator and automotive shafts are often subjected to complex histories of high torques. To provide a basis for fatigue life estimation in such components, a study of fatigue crack propagation in Mode III (anti-plane shear) for a mill-annealed AISI 4140 steel (RB88, 590 MN/m2 tensile strength) has been undertaken, using torsionally-loaded, circumferentially-notched cylindrical specimens. As demonstrated previously for higher strength AISI 4340 steel, Mode III cyclic crack growth rates (dc/dN) IIIcan be related to the alternating stress intensity factor ΔKIII for conditions of small-scale yielding. However, to describe crack propagation behavior over an extended range of crack growth rates (˜10-6 to 10-2 mm per cycle), where crack growth proceeds under elastic-plastic and full plastic conditions, no correlation between (dc/dN) III and ΔKIII is possible. Accordingly, a new parameter for torsional crack growth, termed the plastic strain intensity Γ III, is introduced and is shown to provide a unique description of Mode III crack growth behavior for a wide range of testing conditions, provided a mean load reduces friction, abrasion, and interlocking between mating fracture surfaces. The latter effect is found to be dependent upon the mode of applied loading (i.e., the presence of superimposed axial loads) and the crack length and torque level. Mechanistically, high-torque surfaces were transverse, macroscopically flat, and smeared. Lower torques showed additional axial cracks (longitudinal shear cracking) perpendicular to the main transverse surface. A micro-mechanical model for the main radi l Mode III growth, based on the premise that crack advance results from Mode II coalescence of microcracks initiated at inclusions ahead of the main crack front, is extended to high nominal stress levels, and predicts that Mode III fatigue crack propagation rates should be proportional to the range of plastic strain intensity (ΔΓIII if local Mode II growth rates are

  1. Wide-pulse-high-frequency neuromuscular stimulation of triceps surae induces greater muscle fatigue compared with conventional stimulation.

    Science.gov (United States)

    Neyroud, Daria; Dodd, David; Gondin, Julien; Maffiuletti, Nicola A; Kayser, Bengt; Place, Nicolas

    2014-05-15

    We compared the extent and origin of muscle fatigue induced by short-pulse-low-frequency [conventional (CONV)] and wide-pulse-high-frequency (WPHF) neuromuscular electrical stimulation. We expected CONV contractions to mainly originate from depolarization of axonal terminal branches (spatially determined muscle fiber recruitment) and WPHF contractions to be partly produced via a central pathway (motor unit recruitment according to size principle). Greater neuromuscular fatigue was, therefore, expected following CONV compared with WPHF. Fourteen healthy subjects underwent 20 WPHF (1 ms-100 Hz) and CONV (50 μs-25 Hz) evoked isometric triceps surae contractions (work/rest periods 20:40 s) at an initial target of 10% of maximal voluntary contraction (MVC) force. Force-time integral of the 20 evoked contractions (FTI) was used as main index of muscle fatigue; MVC force loss was also quantified. Central and peripheral fatigue were assessed by voluntary activation level and paired stimulation amplitudes, respectively. FTI in WPHF was significantly lower than in CONV (21,717 ± 11,541 vs. 37,958 ± 9,898 N·s P 0.05). Overall, our results showed a different motor unit recruitment pattern between the two neuromuscular electrical stimulation modalities with a lower FTI indicating greater muscle fatigue for WPHF, possibly limiting the presumed benefits for rehabilitation programs.

  2. Small Crack Growth and Fatigue Life Predictions for High-Strength Aluminium Alloys. Part 1; Experimental and Fracture Mechanics Analysis

    Science.gov (United States)

    Wu, X. R.; Newman, J. C.; Zhao, W.; Swain, M. H.; Ding, C. F.; Phillips, E. P.

    1998-01-01

    The small crack effect was investigated in two high-strength aluminium alloys: 7075-T6 bare and LC9cs clad alloy. Both experimental and analytical investigations were conducted to study crack initiation and growth of small cracks. In the experimental program, fatigue tests, small crack and large crack tests A,ere conducted under constant amplitude and Mini-TWIST spectrum loading conditions. A pronounced small crack effect was observed in both materials, especially for the negative stress ratios. For all loading conditions, most of the fatigue life of the SENT specimens was shown to be crack propagation from initial material defects or from the cladding layer. In the analysis program, three-dimensional finite element and A weight function methods were used to determine stress intensity factors and to develop SIF equations for surface and corner cracks at the notch in the SENT specimens. A plastisity-induced crack-closure model was used to correlate small and large crack data, and to make fatigue life predictions, Predicted crack-growth rates and fatigue lives agreed well with experiments. A total fatigue life prediction method for the aluminum alloys was developed and demonstrated using the crack-closure model.

  3. Age effect on fatigue-induced limb acceleration as a consequence of high-level sustained submaximal contraction.

    Science.gov (United States)

    Huang, Chien-Ting; Huang, Chien-Chun; Young, Ming-Shing; Hwang, Ing-Shiou

    2007-08-01

    In reference to electromyographic measurement, the study was conducted to reassess differences in the behavior of fatigue-related neuromuscular function between young and elderly humans with limb acceleration (LA). Fourteen young and fourteen elderly subjects performed sustained index abduction at 75% of their maximal voluntary contractions (MVC) until task failure. Measures of neuromuscular function, including temporal/spectral features of muscle activity of the first dorsal interosseous (FDI) and LA of the index and hand, were monitored. The results showed a manifest fatigue-induced increase in LA of the index in the elderly group, but not in the young group. In contrast, only the young group developed a significant increase in amplitude of the electromyography (EMG) until task failure. Spectral analyses of LA in the index reflected marked age-dependent reorganization following muscle fatigue, with a greater reduction of relative spectral amplitude of LA in the range of 20-40 Hz, but a lesser reduction in coherence between EMG and LA in the elderly group. In line with fatigue-associated restructuring of LA, the mechanical coupling of the metacarpophalangeal joint was more severely undermined in the elderly group than in the young group. The present study manifested an age-related difference in the relative contributions of neural versus mechanical factors to muscle fatigue. Subsequent to a high-level sustained submaximal isometric contraction, a predominant mechanical failure of the musculotendon complex in the elderly was featured with LA, whereas EMG measurement characterized prevailing impairment of neuromuscular propagation in the young.

  4. Mechanical Fatigue Testing of High-Burnup Fuel for Transportation Applications

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jy-An John [ORNL; Wang, Hong [ORNL

    2015-05-01

    This report describes testing designed to determine the ability of high burnup (HBU) (>45 GWd/MTU) spent fuel to maintain its integrity under normal conditions of transportation. An innovative system, Cyclic Integrated Reversible-bending Fatigue Tester (CIRFT), has been developed at Oak Ridge National Laboratory (ORNL) to test and evaluate the mechanical behavior of spent nuclear fuel (SNF) under conditions relevant to storage and transportation. The CIRFT system is composed of a U-frame equipped with load cells for imposing the pure bending loads on the SNF rod test specimen and measuring the in-situ curvature of the fuel rod during bending using a set up with three linear variable differential transformers (LVDTs).

  5. Effect of defect length on rolling contact fatigue crack propagation in high strength steel

    Directory of Open Access Journals (Sweden)

    T. Makino

    2015-10-01

    Full Text Available The objective of the present paper is to clarify the effect of defect length in depth direction on rolling contact fatigue (RCF crack propagation in high strength steel. RCF test and synchrotron radiation micro computed tomography (SR micro CT imaging were conducted. In the case of the defect with the 15 m diameter, flaking life decreased with increasing defect length. In a comparison of the CT image and the SEM view, the shapes of defects and the locations of the horizontal cracks were almost the same respectively. The mechanism of RCF crack propagation was discussed by finite element (FE analysis. Defects led to higher tensile residual stress than that without defects in the region where the defect exists. The shear stress range at 0.1 mm in depth on the middle line of the defect and the range of mode II stress intensity factor at the bottom of a vertical crack increased with increasing defect length.

  6. Copper Nanoparticle/Multiwalled Carbon Nanotube Composite Films with High Electrical Conductivity and Fatigue Resistance Fabricated via Flash Light Sintering.

    Science.gov (United States)

    Hwang, Hyun-Jun; Joo, Sung-Jun; Kim, Hak-Sung

    2015-11-18

    In this work, multiwalled carbon nanotubes (MWNTs) were employed to improve the conductivity and fatigue resistance of flash light sintered copper nanoparticle (NP) ink films. The effect of CNT weight fraction on the flash light sintering and the fatigue characteristics of Cu NP/CNT composite films were investigated. The effect of carbon nanotube length was also studied with regard to enhancing the conductivity and fatigue resistance of flash light sintered Cu NP/CNT composite films. The flash light irradiation energy was optimized to obtain high conductivity Cu NP/CNT composite films. Cu NP/CNT composite films fabricated via optimized flash light irradiation had the lowest resistivity (7.86 μΩ·cm), which was only 4.6 times higher than that of bulk Cu films (1.68 μΩ·cm). It was also demonstrated that Cu NP/CNT composite films had better durability and environmental stability than those of Cu NPs only.

  7. Fatigue lifetime of steel weldments with high resistance, rough welding, repaired by welding and hammered; Duree de vie en fatigue d'assemblages soudes en acier de construction a haute resistance, bruts de soudage, repares par soudage et marteles

    Energy Technology Data Exchange (ETDEWEB)

    Braid, J.E.M. [Materials Technology Laboratory, Ottawa (Canada); Bell, R. [Mechanical and Aerospace Engineering, Carlton University, Ottawa (Canada); Militaru, D.V. [Centre for Surface Transportation Technology, Ottawa (Canada)

    1999-09-01

    It has been shown in literature that the propagation velocity of fatigue cracks and that the ratio da/dN are relatively independent of the elasticity limit. In order to better use high resistance steels solicited in fatigue, it is necessary to improve the fatigue resistance of weldments: better design and/or post-welding treatments. The improvements obtained by grinding, TIG-refusion, shot-blasting and hammering are indicated. The most part of this study concerns the fatigue resistance of longitudinal welds on rough T assembling, repaired by welding and hammered or not. The steel test pieces are of 350 MPa (specification CSA G 4021350WT) and of 550 MPa (specification HY80). The two steels have the same behavior in fatigue at the rough-welding state. The used repair method restore the initial fatigue characteristics of the rough-welding state. Compared with the rough-welding state, the hammering improves the fatigue resistance of steel weldments (550 MPa) of 175%. (O.M.)

  8. Oxidation and thermal fatigue of coated and uncoated NX-188 nickel-base alloy in a high velocity gas stream

    Science.gov (United States)

    Johnson, J. R.; Young, S. G.

    1972-01-01

    A cast nickel-base superalloy, NX-188, coated and uncoated, was tested in a high-velocity gas stream for resistance to oxidation and thermal fatigue by cycling between room temperature and 980, 1040, and 1090 C. Contrary to the behavior of more conventional nickel-base alloys, uncoated NX-188 exhibited the greatest weight loss at the lowest test temperature. In general, on the basis of weight change and metallographic observations a coating consisting of vapor-deposited Fe-Cr-Al-Y over a chromized substrate exhibited the best overall performance in resistance to oxidation and thermal fatigue.

  9. High-voltage electron-microscopic observation of cyclic slip behavior around a fatigue crack tip in an iron alloy

    Energy Technology Data Exchange (ETDEWEB)

    Takahashi, Yoshimasa [National Institute of Advanced Industrial Science and Technology (AIST), 744 Motooka, Nishi-ku, Fukuoka 819-0395 (Japan)], E-mail: yoshim.takahashi@aist.go.jp; Tanaka, Masaki; Higashida, Kenji [Department of Materials Science and Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395 (Japan); Noguchi, Hiroshi [Department of Mechanical Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395 (Japan)

    2009-04-15

    The cyclic slip behavior around a fatigue crack tip originally located inside a bulk Fe-Si alloy was successfully observed by a high-voltage electron microscope in combination with a novel specimen preparation method. The method, by taking advantages of ion milling and focused ion beam techniques, ensures that the original shape of the crack tip is preserved without introducing additional slips. The observation confirms that the slip bands emitted from the fatigue crack tip are bounded by a labyrinth-like wall structure.

  10. Comparison of cyclic fatigue life of nickel-titanium files: an examination using high-speed camera

    Directory of Open Access Journals (Sweden)

    Taha Özyürek

    2017-08-01

    Full Text Available Objectives To determine the actual revolutions per minute (rpm values and compare the cyclic fatigue life of Reciproc (RPC, VDW GmbH, WaveOne (WO, Dentsply Maillefer, and TF Adaptive (TFA, Axis/SybronEndo nickel-titanium (NiTi file systems using high-speed camera. Materials and Methods Twenty RPC R25 (25/0.08, 20 WO Primary (25/0.08, and 20 TFA ML 1 (25/0.08 files were employed in the present study. The cyclic fatigue tests were performed using a dynamic cyclic fatigue testing device, which has an artificial stainless steel canal with a 60° angle of curvature and a 5-mm radius of curvature. The files were divided into 3 groups (group 1, RPC R25 [RPC]; group 2, WO Primary [WO]; group 3, TF Adaptive ML 1 [TFA]. All the instruments were rotated until fracture during the cyclic fatigue test and slow-motion videos were captured using high-speed camera. The number of cycles to failure (NCF was calculated. The data were analyzed statistically using one-way analysis of variance (ANOVA, p < 0.05. Results The slow-motion videos were indicated that rpm values of the RPC, WO, and TFA groups were 180, 210, and 425, respectively. RPC (3,464.45 ± 487.58 and WO (3,257.63 ± 556.39 groups had significantly longer cyclic fatigue life compared with TFA (1,634.46 ± 300.03 group (p < 0.05. There was no significant difference in the mean length of the fractured fragments. Conclusions Within the limitation of the present study, RPC and WO NiTi files showed significantly longer cyclic fatigue life than TFA NiTi file.

  11. In Situ Imaging of High Cycle Fatigue Crack Growth in Single Crystal Nickel-Base Superalloys by Synchrotron X-Radiation

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Liu; Husseini, Naji S.; Torbet, Christopher J.; Kumah, Divine P.; Clarke, Roy; Pollock, Tresa M.; Jones, J.Wayne (Michigan)

    2008-05-01

    A novel X-ray synchrotron radiation approach is described for real-time imaging of the initiation and growth of fatigue cracks during ultrasonic fatigue (f=20 kHz). We report here on new insights on single crystal nickel-base superalloys gained with this approach. A portable ultrasonic fatigue instrument has been designed that can be installed at a high-brilliance X-ray beamline. With a load line and fatigue specimen configuration, this instrument produces stable fatigue crack propagation for specimens as thin as 150 {mu}m. The in situ cyclic loading/imaging system has been used initially to image real-time crystallographic fatigue and crack growth under positive mean axial stress in the turbine blade alloy CMSX-4.

  12. Static, Fire and Fatigue Tests of Ultra High-Strength Fibre Reinforced Concrete and Ribbed Bars

    DEFF Research Database (Denmark)

    Hansen, Lars Pilegaard; Heshe, Gert

    2001-01-01

    - Densit Joint Cast ®. Also the connections between the columns and the slabs are made of this very strong concrete material. The paper describes some of the static tests carried out as well as some fire tests. Further, 2 chapters deal with some fatigue tests of the reinforcing bars as well as some fatigue...

  13. The effect of low temperatures on the fatigue of high-strength structural grade steels

    NARCIS (Netherlands)

    Walters, C.L.

    2014-01-01

    It is well-known that for fracture, ferritic steels undergo a sudden transition from ductile behavior at higher temperatures to brittle cleavage failure at lower temperatures. However, this phenomenon has not received much attention in the literature on fatigue. The so-called Fatigue Ductile-Brittle

  14. Do high job demands increase intrinsic motivation or fatigue or both? The role of job control and job social support

    NARCIS (Netherlands)

    Van Yperen, N.W.; Hagedoorn, M.

    2003-01-01

    Examined whether job control and job social support reduce signs of fatigue and enhance intrinsic motivation among employees facing high job demands. 555 nurses (mean age 35.5 yrs) working at specialized units for patients with different levels of mental deficiency completed surveys regarding: (1) j

  15. Fatigue Behavior of Ultrafine-Grained Medium Carbon Steel with Different Carbide Morphologies Processed by High Pressure Torsion

    Directory of Open Access Journals (Sweden)

    Christoph Ruffing

    2015-05-01

    Full Text Available The increased attention ultrafine grained (UFG materials have received over the last decade has been inspired by their high strength in combination with a remarkable ductility, which is a promising combination for good fatigue properties. In this paper, we focus on the effect of different carbide morphologies in the initial microstructure on the fatigue behavior after high pressure torsion (HPT treatment of SAE 1045 steels. The two initial carbide morphologies are spheroidized as well as tempered states. The HPT processing increased the hardness of the spheroidized and tempered states from 169 HV and 388 HV to a maximum of 511 HV and 758 HV, respectively. The endurance limit increased linearly with hardness up to about 500 HV independent of the carbide morphology. The fracture surfaces revealed mostly flat fatigue fracture surfaces with crack initiation at the surface or, more often, at non-metallic inclusions. Morphology and crack initiation mechanisms were changed by the severe plastic deformation. The residual fracture surface of specimens with spheroidal initial microstructures showed well-defined dimple structures also after HPT at high fatigue limits and high hardness values. In contrast, the specimens with a tempered initial microstructure showed rather brittle and rough residual fracture surfaces after HPT.

  16. Do high job demands increase intrinsic motivation or fatigue or both? The role of job control and job social support

    NARCIS (Netherlands)

    Van Yperen, N.W.; Hagedoorn, M.

    2003-01-01

    Examined whether job control and job social support reduce signs of fatigue and enhance intrinsic motivation among employees facing high job demands. 555 nurses (mean age 35.5 yrs) working at specialized units for patients with different levels of mental deficiency completed surveys regarding: (1)

  17. Caregivers of patients with cancer fatigue: a high level of symptom burden.

    Science.gov (United States)

    Clark, Matthew M; Atherton, Pamela J; Lapid, Maria I; Rausch, Sarah M; Frost, Marlene H; Cheville, Andrea L; Hanson, Jean M; Garces, Yolanda I; Brown, Paul D; Sloan, Jeff A; Richardson, Jarrett W; Piderman, Katherine M; Rummans, Teresa A

    2014-03-01

    Fatigue is the problematic symptom identified by patients with cancer. However, fatigue has not been widely examined in caregivers of patients with cancer. In this study, 131 caregivers of patients diagnosed with advanced stage cancer and actively receiving radiotherapy reported experiencing the most difficulties with fatigue (mean 46.9; on a 0-100 scale, with a 10-point difference having clinical meaning) at baseline and at a 6-month follow-up (mean 48.3). This is in sharp contrast to other domains of quality of life and functioning being rated in the 60s, 70s and 80s by the caregivers of patients with cancer. Given the level of fatigue reported by the caregivers of patients with cancer, if confirmed by other investigators in larger and more diverse samples, interventions targeting caregiver fatigue should be explored.

  18. Impact of choice of stabilized hysteresis loop on the end result of investigation of high-strength low-alloy (HSLA steel on low cycle fatigue

    Directory of Open Access Journals (Sweden)

    S. Bulatović

    2014-10-01

    Full Text Available High strength low-alloy steel under low cycle fatigue at a certain level of strain controlled achieve stabilized condition. During the fatigue loading stabilized hysteresis loop is determined, which typical cycle of stabilization is calculated as half number of cycles to failure. Stabilized hysteresis loop is a representative of all hysteresis and it’s used to determine all of the parameters for the assessment of low cycle fatigue. This paper shows comparison of complete strain-life curves of low cycle fatigue for two chosen stabilized hysteresis loop cycles of base metal HSLA steel marked as Nionikral 70.

  19. Effects of load ratio, R, and test temperature on high cycle fatigue behavior of nano-structured Al-4Y-4Ni-X alloy composites

    Energy Technology Data Exchange (ETDEWEB)

    El-Shabasy, Adel B., E-mail: ashabasy@hotmail.com [Department of Design and Production Engineering, Faculty of Engineering, Ain Shams University, Cairo 11517 (Egypt); Hassan, Hala A. [Department of Design and Production Engineering, Faculty of Engineering, Ain Shams University, Cairo 11517 (Egypt); Lewandowski, John J. [Department of Material' s Science and Engineering, Case Western Reserve University, Cleveland, OH 44106 (United States)

    2012-12-15

    Nanostructured Al-4Y-4Ni-X composites created by extruding atomized amorphous powders at different extrusion ratios were tested under high cycle bending fatigue at load ratios, R=0.1, 0.33 and -1 at room temperature, 149 Degree-Sign C and 260 Degree-Sign C. Increasing the extrusion ratio generally improved the fatigue life and the fatigue limits were well in excess of that obtained on conventional aluminum alloys at all temperatures tested. The fatigue limits obtained in this work were also compared to previously reported values for a nanostructured composite Al-Gd-Ni-Fe alloy produced via similar means.

  20. Inflammation and fatigue dimensions in advanced cancer patients and cancer survivors: An explorative study

    OpenAIRE

    2012-01-01

    textabstractBACKGROUND: Inflammation may underlie cancer-related fatigue; however, there are no studies that assess the relation between fatigue and cytokines in patients with advanced disease versus patients without disease activity. Furthermore, the relation between cytokines and the separate dimensions of fatigue is unknown. Here, association of plasma levels of inflammatory markers with physical fatigue and mental fatigue was explored in advanced cancer patients and cancer survivors. METH...

  1. [Mediator effect analysis of the trait coping style on job stress and fatigue of the military personnel stationed in plateau and high cold region].

    Science.gov (United States)

    Zhang, J J; Jia, J M; Tao, N; Song, Z X; Ge, H; Jiang, Y; Tian, H; Qiu, E C; Tang, J H; Liu, J W

    2017-03-20

    Objective: To investigate the fatigue status of military personnel stationed in plateau and high cold region, and to analyze the mediator effect of trait coping style on job stress and fatigue. Methods: In October 2010, with the method of cluster random sampling survey, 531 military personnel stationed in plateau and high cold region were chosen as subject. The fatigue status were evaluated by the Chinese version multidimensional fatigue inventory (MFI-20) , job stress were evaluated by the Job Stress Survey (JSS) , and trait coping style were evaluated by the Trait Coping Style Questionnaire (TCSQ) . Results: According to the information of different population characteristics, mean rank of physical fatigue about the urban (town) group were higher than that of rural group (Z=-2.200, Pmilitary officers, sergeancy and soldier group (F=18.965, Pmilitary officers, sergeancy and soldier group (F=14.711, P<0.05) . The score of negative coping style were positively correlated with the score of physical fatigue (r(s)=0.129) , reduced activity (r(s)=0.123) , reduced motivation (r(s)=0.149) and general fatigue (r(s)=0.174) respectively, the score of organizational support lack strength were positively correlated with the score of physical fatigue (r(s)=0.090) , reduced activity (r(s)=0.098) , reduced motivation (r(s)=0.099) and general fatigue (r(s)=0.130) respectively. The mediator effect of negative coping style on the job stress and fatigue was 0.013 (P<0.01) . Conclusion: The fatigue statuses of the urban (town) group and the up or equal 20-years old age group are poor, and the negative coping style plays mediator effect on the job stress and fatigue.

  2. Effect of microstructure on fatigue behavior of advanced high strength steels produced by quenching and partitioning and the role of retained austenite

    Energy Technology Data Exchange (ETDEWEB)

    Diego-Calderón, I. de, E-mail: irenedediego.calderon@imdea.org [IMDEA Materials Institute, Calle Eric Kandel 2, 28906 Getafe, Madrid (Spain); Rodriguez-Calvillo, P. [Fundació CTM Centre Tecnològic, Plaza de la Ciencia 2, 08243 Manresa (Spain); Departamento de Ciencia de los Materiales e Ingeniería Metalúrgica, Universitat Politècnica de Catalunya, Av. Diagonal 647, 08028 Barcelona (Spain); Lara, A. [Fundació CTM Centre Tecnològic, Plaza de la Ciencia 2, 08243 Manresa (Spain); Molina-Aldareguia, J.M. [IMDEA Materials Institute, Calle Eric Kandel 2, 28906 Getafe, Madrid (Spain); Petrov, R.H. [Department of Materials Science and Engineering, Ghent University, Technologiepark 903, B-9052 Zwijnaarde (Ghent) (Belgium); Department of Materials Science and Engineering, Delft University of Technology, 2628 CD Delft (Netherlands); De Knijf, D. [Department of Materials Science and Engineering, Ghent University, Technologiepark 903, B-9052 Zwijnaarde (Ghent) (Belgium); Sabirov, I. [IMDEA Materials Institute, Calle Eric Kandel 2, 28906 Getafe, Madrid (Spain)

    2015-08-12

    Despite the significant body of research on mechanical properties of quenched and partitioned (Q&P) steels, their fatigue behavior has not been investigated. This work focuses on the effect of microstructure on high cycle fatigue of Q&P steels and microstructural evolution during cyclic loading. It is demonstrated that increased content of retained austenite (RA) improves fatigue limit of Q&P steels that is related to delay of crack propagation due to austenite–martensite phase transformation. Increasing stress amplitude promotes austenite–martensite phase transformation during cycling loading. It is shown that size and crystallographic orientation of RA are the main factors determining its stability, whereas its shape and spatial distribution do not seem to affect it significantly. Fatigue crack initiation during fatigue testing with high stress amplitudes occurs by intergranular cracking, whereas transgranular cracking controls fatigue crack initiation during cycling loading with lower stress amplitudes. Transgranular crack propagation dominates in the second stage of fatigue at all stress amplitudes. The final stage of fatigue is also not affected by the stress amplitude. It is suggested that fatigue life of Q&P steels can be enhanced via improvement of strength of grain/interphase boundaries.

  3. Effect of short-term fatigue, induced by high-intensity exercise, on the profile of the ground reaction force during single-leg anterior drop-jumps

    Science.gov (United States)

    Watanabe, Saya; Aizawa, Junya; Shimoda, Manabu; Enomoto, Mitsuhiro; Nakamura, Tomomasa; Okawa, Atushi; Yagishita, Kazuyoshi

    2016-01-01

    [Purpose] Fatigue may be an important contributing factor to non-contact anterior cruciate ligament injuries in sports. The purpose of this study was to evaluate the effects of controlled lower limb fatigue, induced by a short-term, high-intensity exercise protocol, on the profile of the ground reaction force during landings from single-leg anterior drop-jumps. [Subjects and Methods] Twelve healthy males, 18 to 24 years old, performed single-leg anterior drop-jumps, from a 20 cm height, under two conditions, ‘fatigue’ and ‘non-fatigue’. Short-term fatigue was induced by high-intensity interval cycling on an ergometer. Effects of fatigue on peak vertical ground reaction force, time-to-peak of the vertical ground reaction force, and loading rate were evaluated by paired t-test. [Results] Fatigue shortened the time-to-peak duration of the vertical ground reaction force by 10% (non-fatigue, 44.0 ± 16.8 ms; fatigue, 39.6 ± 15.8 ms). Fatigue also yielded a 3.6% lowering in peak vertical ground reaction force and 9.4% increase in loading rate, although these effects were not significant. [Conclusion] The effects of fatigue in reducing time-to-peak of the vertical ground reaction force during single-leg anterior drop-jumps may increase the risk for non-contact anterior cruciate ligament injury in males. PMID:28174454

  4. Factors Affecting Quality of Life and Fatigue in Gynaecologic Cancer Patients

    Directory of Open Access Journals (Sweden)

    Güngör İ

    2017-06-01

    Full Text Available Background: Cancer-related fatigue (CRF is the most commonly reported and most distressing symptom in cancer patients. Health-related quality of life (QOL is an important outcome in cancer management, the authors sought to better understand its determinants. Aim: This study aims to identify quality of life and fatigue levels and the affecting factors in gynaecologic cancer patients. Method: This descriptive and cross-sectional study was conducted with 154 volunteer women with gynaecologic cancer. The data were collected through the interview form, functional assessment of cancer therapy-general (FACT-G Quality of Life Scale, and Piper Fatigue Scale. Results: The mean score of total quality of life in gynaecologic cancer patients was low, 53.4 ± 15.4. Physical and emotional states were found to be the mostly affected states in the quality of life. According to the Piper Fatigue Scale, the total fatigue score was mild, 3.5 ± 2.4. Total fatigue scores were found to be high in metastatic cancers. Multivariate analyses indicate that the most important factor affecting the quality of life is economic condition, and the most important variables affecting fatigue are the level of activity and use of medicine. Conclusion: This study found that quality of life dimensions in women with gynaecologic cancer was affected by factors such as cancer type, time of diagnosis, and stage and spread of the cancer.

  5. Benefits of high gradient solidification for creep and low cycle fatigue of AM1 single crystal superalloy

    Energy Technology Data Exchange (ETDEWEB)

    Steuer, S., E-mail: Susanne.Steuer@ensma.fr [Institut Pprime, CNRS – ENSMA – Université de Poitiers, UPR CNRS 3346, Department of Physics and Mechanics of Materials, ENSMA – Téléport 2, 1 avenue Clément Ader, BP 40109, 86961 Futuroscope Chasseneuil Cedex (France); Villechaise, P. [Institut Pprime, CNRS – ENSMA – Université de Poitiers, UPR CNRS 3346, Department of Physics and Mechanics of Materials, ENSMA – Téléport 2, 1 avenue Clément Ader, BP 40109, 86961 Futuroscope Chasseneuil Cedex (France); Pollock, T.M. [Materials Department, University of California Santa Barbara, Santa Barbara, CA 93106-5050 (United States); Cormier, J. [Institut Pprime, CNRS – ENSMA – Université de Poitiers, UPR CNRS 3346, Department of Physics and Mechanics of Materials, ENSMA – Téléport 2, 1 avenue Clément Ader, BP 40109, 86961 Futuroscope Chasseneuil Cedex (France)

    2015-10-01

    The influence of high thermal gradient processing on the creep and low cycle fatigue properties of the AM1 Ni-based single crystal superalloy has been studied. Isothermal creep (from 750 °C up to 1200 °C) and low cycle fatigue (750 °C and 950 °C) experiments were performed for AM1 alloy solidified with a conventional radiation cooled (Bridgman) and higher thermal gradient liquid-metal cooled (LMC) casting process to produce coarse and finer-scaled dendritic structures, respectively. There was no significant effect of the casting technique on creep properties, due to the very similar microstructures (γ′-size and γ-channel width) established after full heat treatment of both Bridgman and LMC samples. For low cycle fatigue properties, the benefit of the higher gradient LMC process was dependent on the testing temperature. At 750 °C, cracks primarily initiated at pores created by solidification shrinkage in both Bridgman and LMC samples. Samples produced by the LMC technique demonstrated fatigue lives up to 4 times longer, compared to the Bridgman samples, due to refined porosity. At 950 °C the low cycle fatigue properties of the LMC and conventionally solidified material were not distinguishable due to a shift of crack initiation sites from internal pores to oxidized surface layers or near-surface pores. The benefit of the LMC approach was, however, apparent in fatigue at 950 °C when testing in a vacuum environment. Based on these results, a crack initiation model based on the local slip activity close to casting defect is proposed.

  6. High-Throughput Computation and the Applicability of Monte Carlo Integration in Fatigue Load Estimation of Floating Offshore Wind Turbines

    Energy Technology Data Exchange (ETDEWEB)

    Graf, Peter A.; Stewart, Gordon; Lackner, Matthew; Dykes, Katherine; Veers, Paul

    2016-05-01

    Long-term fatigue loads for floating offshore wind turbines are hard to estimate because they require the evaluation of the integral of a highly nonlinear function over a wide variety of wind and wave conditions. Current design standards involve scanning over a uniform rectangular grid of metocean inputs (e.g., wind speed and direction and wave height and period), which becomes intractable in high dimensions as the number of required evaluations grows exponentially with dimension. Monte Carlo integration offers a potentially efficient alternative because it has theoretical convergence proportional to the inverse of the square root of the number of samples, which is independent of dimension. In this paper, we first report on the integration of the aeroelastic code FAST into NREL's systems engineering tool, WISDEM, and the development of a high-throughput pipeline capable of sampling from arbitrary distributions, running FAST on a large scale, and postprocessing the results into estimates of fatigue loads. Second, we use this tool to run a variety of studies aimed at comparing grid-based and Monte Carlo-based approaches with calculating long-term fatigue loads. We observe that for more than a few dimensions, the Monte Carlo approach can represent a large improvement in computational efficiency, but that as nonlinearity increases, the effectiveness of Monte Carlo is correspondingly reduced. The present work sets the stage for future research focusing on using advanced statistical methods for analysis of wind turbine fatigue as well as extreme loads.

  7. Anti-hypotensive treatment and endothelin blockade synergistically antagonize exercise fatigue in rats under simulated high altitude.

    Directory of Open Access Journals (Sweden)

    Daniel Radiloff

    Full Text Available Rapid ascent to high altitude causes illness and fatigue, and there is a demand for effective acute treatments to alleviate such effects. We hypothesized that increased oxygen delivery to the tissue using a combination of a hypertensive agent and an endothelin receptor A antagonist drugs would limit exercise-induced fatigue at simulated high altitude. Our data showed that the combination of 0.1 mg/kg ambrisentan with either 20 mg/kg ephedrine or 10 mg/kg methylphenidate significantly improved exercise duration in rats at simulated altitude of 4,267 m, whereas the individual compounds did not. In normoxic, anesthetized rats, ephedrine alone and in combination with ambrisentan increased heart rate, peripheral blood flow, carotid and pulmonary arterial pressures, breathing rate, and vastus lateralis muscle oxygenation, but under inspired hypoxia, only the combination treatment significantly enhanced muscle oxygenation. Our results suggest that sympathomimetic agents combined with endothelin-A receptor blockers offset altitude-induced fatigue in rats by synergistically increasing the delivery rate of oxygen to hypoxic muscle by concomitantly augmenting perfusion pressure and improving capillary conductance in the skeletal muscle. Our findings might therefore serve as a basis to develop an effective treatment to prevent high-altitude illness and fatigue in humans.

  8. Fatigue of extracted lead zirconate titanate multilayer actuators under unipolar high field electric cycling

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Hong, E-mail: wangh@ornl.gov; Lee, Sung-Min; Wang, James L. [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Lin, Hua-Tay [School of Mechanical and Electronic Engineering, Guangdong University of Technology, Guangzhou, 510006 (China)

    2014-12-21

    Testing of large prototype lead zirconate titanate (PZT) stacks presents substantial technical challenges to electronic testing systems, so an alternative approach that uses subunits extracted from prototypes has been pursued. Extracted 10-layer and 20-layer plate specimens were subjected to an electric cycle test under an electric field of 3.0/0.0 kV/mm, 100 Hz to 10{sup 8} cycles. The effects of measurement field level and stack size (number of PZT layers) on the fatigue responses of piezoelectric and dielectric coefficients were observed. On-line monitoring permitted examination of the fatigue response of the PZT stacks. The fatigue rate (based on on-line monitoring) and the fatigue index (based on the conductance spectrum from impedance measurement or small signal measurement) were developed to quantify the fatigue status of the PZT stacks. The controlling fatigue mechanism was analyzed against the fatigue observations. The data presented can serve as input to design optimization of PZT stacks and to operation optimization in critical applications, such as piezoelectric fuel injectors in heavy-duty diesel engines.

  9. High-temperature low cycle fatigue behavior of a gray cast iron

    Energy Technology Data Exchange (ETDEWEB)

    Fan, K.L., E-mail: 12klfan@tongji.edu.cn; He, G.Q.; She, M.; Liu, X.S.; Lu, Q.; Yang, Y.; Tian, D.D.; Shen, Y.

    2014-12-15

    The strain controlled low cycle fatigue properties of the studied gray cast iron for engine cylinder blocks were investigated. At the same total strain amplitude, the low cycle fatigue life of the studied material at 523 K was higher than that at 423 K. The fatigue behavior of the studied material was characterized as cyclic softening at any given total strain amplitude (0.12%–0.24%), which was attributed to fatigue crack initiation and propagation. Moreover, this material exhibited asymmetric hysteresis loops due to the presence of the graphite lamellas. Transmission electron microscopy analysis suggested that cyclic softening was also caused by the interactions of dislocations at 423 K, such as cell structure in ferrite, whereas cyclic softening was related to subgrain boundaries and dislocation climbing at 523 K. Micro-analysis of specimen fracture appearance was conducted in order to obtain the fracture characteristics and crack paths for different strain amplitudes. It showed that the higher the temperature, the rougher the crack face of the examined gray cast iron at the same total strain amplitude. Additionally, the microcracks were readily blunted during growth inside the pearlite matrix at 423 K, whereas the microcracks could easily pass through pearlite matrix along with deflection at 523 K. The results of fatigue experiments consistently showed that fatigue damage for the studied material at 423 K was lower than that at 523 K under any given total strain amplitude. - Highlights: • The low cycle fatigue behavior of the HT250 for engine cylinder blocks was investigated. • TEM investigations were conducted to explain the cyclic deformation response. • The low cycle fatigue cracks of HT250 GCI were studied by SEM. • The fatigue life of the examined material at 523 K is higher than that at 423 K.

  10. Aging behavior and fatigue crack propagation of high Zn-containing Al-Zn-Mg-Cu alloys with zinc variation

    Directory of Open Access Journals (Sweden)

    Kai Wen

    2017-04-01

    Full Text Available In the present work, the influence of two-step aging treatments on hardness, electrical conductivity and mechanical properties of two high Zn-containing Al-Zn-Mg-Cu alloys with zinc content variation was investigated and the detailed T76 aging parameters were proposed. The microstructure of the precipitates were studied by transmission electron microscopy (TEM and high-resolution transmission electron microscopy (HREM and then quantitatively investigated with the aid of an image analysis. The fatigue performances were researched by the fatigue crack propagation (FCP rate test and fracture morphology was observed with scanning electron microscopy (SEM. The results show that the matrix precipitate size distributions of both alloys had significant difference, so as to fatigue crack propagation rates and fracture appearance. The shear and bypass mechanisms of dislocation-precipitate interactions were employed to explain the difference. Among the shearable precipitates, the proportion of larger size precipitates for the higher zinc content alloy is bigger than that for the lower zinc content alloy. The coarse shearable precipitates hinder the propagation of the fatigue cracks, leading to inferior FCP rate. For both alloys, the shear mechanism possesses the dominant factor, finally causing a preponderance in the FCP resistance for the higher zinc content alloy than the lower one.

  11. Fatigue crack growth behaviors of a new burn-resistant highly-stabilized beta titanium alloy

    Institute of Scientific and Technical Information of China (English)

    WU Huan; ZHAO Yongqing; ZENG Weidong; QIAN Li

    2009-01-01

    This article presents the fatigue crack growth (FCG) behaviors of a new burn-resistant highly-stabilized beta Ti40 alloy. The FCG rotes were analyzed. The fracture surfaces and the side surfaces of the test samples were explored. The results show that frequency affects the cracking behaviors of Ti40 alloy. Temperature also plays an important role in Ti40 alloy cracking. At room temperature (25℃), when the frequency increases, the cracking rate changes a little in the range of low stress intensity factor (ΔK), while it changes significantly when ΔK is high. At 500℃, the cracking rate of Ti40 alloy changes significantly during all the course of clacking. The frequency also affects the microstructure patterns of Ti40 alloy. A number of secondary cracks appear in the area more than 200 μm from the main crack at a high ΔK when the fre-quency is 1 Hz, but only a few secondary cracks exist when the frequency is 10 Hz. Facet image is the main image of the fracture surfaces when the frequency is 1 Hz. While, ductile striation occupies most of the area of fracture surfaces when the frequency is 10 Hz.

  12. Work-related fatigue: the specific case of highly educated women in the Netherlands.

    Science.gov (United States)

    Verdonk, Petra; Hooftman, Wendela E; van Veldhoven, Marc J P M; Boelens, Louise R M; Koppes, Lando L J

    2010-03-01

    This study aims to establish the prevalence of high work-related fatigue (need for recovery, NFR) among employees and to explain group differences categorized by gender, age, and education. The study particularly aims to clarify prevalence and explanatory factors in highly educated women. In 2005 and 2006, large representative samples of 80,000 Dutch employees (net response rate 33.0%; N = 47,263) received the Netherlands working conditions survey questionnaire. First, we calculated the prevalence of high NFR for men and women with different age and education levels. The average prevalence of high NFR was 28.8% and was highest among highly educated women (35.2%) in particular those aged 50-64 years (40.3%). Second, logistic regression analyses were used to compare subgroups' NFR in relation to situational factors, working conditions, and health. Three comparisons were made: (1) highly educated women versus men; (2) highly educated versus lower educated women and; (3) older highly educated versus younger highly educated women. The situational, working conditions and health factors in our model did not explain the gender differences among highly educated employees (OR = 1.37; CI = 1.3-1.5, adjusted for all factors OR = 1.32; CI = 1.2-1.5). Despite that lower autonomy and workplace violence explained highly educated women's NFR, working fewer hours counterbalanced this. Time pressure in work largely explained the differences in NFR among women at different education levels (crude OR 1.44; CI = 1.4-1.5, adjusted OR 1.14; CI = 1.0-1.3). In the age comparison, lower health ratings, more adverse working conditions, and working as a teacher explained older highly educated women's high prevalence of high NFR (crude OR 1.32; CI = 1.2-1.5, adjusted OR 0.94; CI = 0.8-1.2). NFR has high prevalence in highly educated women (35.2%) in particular those aged 50-64 years (40.3%). Our model did not explain gender differences in NFR, because working fewer hours counterbalanced the

  13. Experimental investigation of crack initiation and propagation in high- and gigacycle fatigue in titanium alloys by study of morphology of fracture

    Directory of Open Access Journals (Sweden)

    M.V. Bannikov

    2016-01-01

    Full Text Available Fatigue (high- and gigacycle crack initiation and its propagation in titanium alloys with coarse and fine grain structure are studied by fractography analysis of fracture surface. Fractured specimens were analyzed by interferometer microscope and electronic microscope to improve methods of monitoring of damage accumulation during fatigue test and verify the models for fatigue crack kinetics. Fatigue strength was estimated for high cycle fatigue (HCF regime using the Luong method [1] by “in-situ” infrared scanning of the sample surface for the step-wise loading history for different grain size metals. Fine grain alloys demonstrated higher fatigue resistance for both HCF and gigacycle fatigue regimes. Fracture surface analysis for cylindrical samples was carried out using optical and electronic microscopy method. High resolution profilometry (interferometerprofiler New View 5010 data of fracture surface roughness allowed us to estimate scale invariance (the Hurst exponent and to establish the existence of two characteristic areas of damage localization (different values of the Hurst exponent. Area 1 with diameter ~300 μm has the pronounced roughness and is associated with damage localization hotspot. Area 2 shows less amplitude roughness, occupies the rest fracture surface and considered as the trace of the fatigue crack path corresponding to the Paris kinetics

  14. High-Temperature Fatigue of a Hybrid Aluminum Metal Matrix Composite

    Science.gov (United States)

    Clark, J. T.; Sanders, P. G.

    2014-01-01

    An aluminum metal matrix composite (MMC) brake drum was tested in fatigue at room temperature and extreme service temperatures. At room temperature, the hybrid composite did not fail and exceeded estimated vehicle service times. At higher temperatures (62 and 73 pct of the matrix eutectic), fatigue of a hybrid particle/fiber MMC exhibited failure consistent with matrix overloading. Overaging of the A356 matrix coupled with progressive fracture of the SiC particles combined to create the matrix overload condition. No evidence of macro-fatigue crack initiation or growth was observed, and the matrix-particle interface appeared strong with no debonding, visible matrix phases, or porosity. An effective medium model was constructed to test the hypothesis that matrix overloading was the probable failure mode. The measured particle fracture rate was fit using realistic values of the SiC Weibull strength and modulus, which in turn predicted cycles to failure within the range observed in fatigue testing.

  15. Damage estimates for European and U.S.sites using the U.S. high-cycle fatigue data base

    Energy Technology Data Exchange (ETDEWEB)

    Sutherland, H.J. [Wind Energy Technology, Sandia National Lab., Albuquerque, NM (United States)

    1996-09-01

    This paper uses two high-cycle fatigue data bases, one for typical U.S. blade materials and one for European materials, to analyze the service lifetime of a wind turbine blade subjected to the WISPER load spectrum for northern European sites and the WISPER protocol load spectrum for U.S. wind farm sites. The U.S. data base contains over 2200 data points that were obtained using coupon testing procedures. These data are used to construct a Goodman diagram that is suitable for analyzing wind turbine blades. This result is compared to the Goodman diagram derived from the European fatigue data base FACT. The LIFE2 fatigue analysis code for wind turbines is then used to predict the service lifetime of a turbine blade subjected to the two loading histories. The results of this study indicate that the WISPER load spectrum from northern European sites significantly underestimates the WISPER protocol load spectrum from a U.S. wind farm site, i.e., the WISPER load spectrum significantly underestimates the number and magnitude of the loads observed at a U.S. wind farm site. Further, the analysis demonstrate that the European and the U.S. fatigue material data bases are in general agreement for the prediction of tensile failures. However, for compressive failures, the two data bases are significantly different, with the U.S. data base predicting significantly shorter service lifetimes than the European data base. (au) 14 refs.

  16. Present Situation of the Anti-Fatigue Processing of High-Strength Steel Internal Thread Based on Cold Extrusion Technology: A Review

    Science.gov (United States)

    Miao, Hong; Jiang, Cheng; Liu, Sixing; Zhang, Shanwen; Zhang, Yanjun

    2017-03-01

    The adoption of cold-extrusion forming for internal thread net forming becomes an important component of anti-fatigue processing with the development of internal thread processing towards high performance, low cost and low energy consumption. It has vast application foreground in the field of aviation, spaceflight, high speed train and etc. The internal thread processing and anti-fatigue manufacture technology are summarized. In terms of the perspective of processing quality and fatigue serving life, the advantages and disadvantages of the processing methods from are compared. The internal thread cold-extrusion processing technology is investigated for the purpose of improving the anti-fatigue serving life of internal thread. The superiorities of the plastic deformation law and surface integrity of the metal layer in the course of cold extrusion for improving its stability and economy are summed up. The proposed research forecasts the development tendency of the internal thread anti-fatigue manufacturing technology.

  17. Rolling Contact Fatigue Performances of Carburized and High-C Nanostructured Bainitic Steels

    Directory of Open Access Journals (Sweden)

    Yanhui Wang

    2016-11-01

    Full Text Available In the present work, the nanostructured bainitic microstructures were obtained at the surfaces of a carburized steel and a high-C steel. The rolling contact fatigue (RCF performances of the two alloy steels with the same volume fraction of undissolved carbide were studied under lubrication. Results show that the RCF life of the carburized nanostructured bainitic steel is superior to that of the high-C nanostructured bainitic steel in spite of the chemical composition, phase constituent, plate thickness of bainitic ferrite, hardness, and residual compressive stress value of the contact surfaces of the two steels under roughly similar conditions. The excellent RCF performance of the carburized nanostructured bainitic steel is mainly attributed to the following reasons: finer carbide dispersion distribution in the top surface, the higher residual compressive stress values in the carburized layer, the deeper residual compressive stress layer, the higher work hardening ability, the larger amount of retained austenite transforming into martensite at the surface and the more stable untransformed retained austenite left in the top surface of the steel.

  18. Rolling Contact Fatigue Performances of Carburized and High-C Nanostructured Bainitic Steels.

    Science.gov (United States)

    Wang, Yanhui; Zhang, Fucheng; Yang, Zhinan; Lv, Bo; Zheng, Chunlei

    2016-11-25

    In the present work, the nanostructured bainitic microstructures were obtained at the surfaces of a carburized steel and a high-C steel. The rolling contact fatigue (RCF) performances of the two alloy steels with the same volume fraction of undissolved carbide were studied under lubrication. Results show that the RCF life of the carburized nanostructured bainitic steel is superior to that of the high-C nanostructured bainitic steel in spite of the chemical composition, phase constituent, plate thickness of bainitic ferrite, hardness, and residual compressive stress value of the contact surfaces of the two steels under roughly similar conditions. The excellent RCF performance of the carburized nanostructured bainitic steel is mainly attributed to the following reasons: finer carbide dispersion distribution in the top surface, the higher residual compressive stress values in the carburized layer, the deeper residual compressive stress layer, the higher work hardening ability, the larger amount of retained austenite transforming into martensite at the surface and the more stable untransformed retained austenite left in the top surface of the steel.

  19. Investigation of Contact Fatigue of High Strength Steel Gears Subjected to Surface Treatment

    Science.gov (United States)

    Dimitrov, L.; Michalopoulos, D.; Apostolopoulos, Ch. Alk.; Neshkov, T. D.

    2009-10-01

    In this paper the contact fatigue resistance of gearwheel teeth, subjected to shot-peening treatment, was investigated experimentally and analytically. The main objective was the evaluation and prediction of fatigue crack initiation, propagation, direction, and rate. A specially designed experimental rig was used to test a number of spur gears with the following characteristics: (a) unhardened, thermally untreated unpeened surfaces, (b) thermally treated unpeened surfaces, (c) unhardened peened surfaces, and (d) thermally treated peened surfaces. The theoretical model assumed initiation and propagation of surface cracks of gears operating in the elastohydrodynamic lubrication regime while loading was due to simultaneous rolling and sliding. Finite element modeling was used for the calculation of the stress field at the gear teeth. Comparison of the experimental and analytical results showed considerable improvement in the contact fatigue strength of thermally treated gear teeth and especially those that underwent shot peening, which increased surface durability. The residual stresses induced by shot peening are mainly effective in stopping microcrack propagation. When shot peening is applied on thermally untreated gear teeth surface, it increases the contact fatigue life of the material by 17% at 7 × 105 loading cycles. If shot peening is applied on carburized gear teeth surfaces, it increases the surface fatigue life by approximately 8% at 106 cycles. Contact fatigue and eventual pitting are treated as a normal consequence of the operation of machine elements. To study this failure process different types of testing machines have been designed. The purpose of this paper is the presentation and evaluation of a new design experimental rig for studying contact fatigue damage of gear teeth subjected to different load patterns.

  20. The Total Work Measured During a High Intensity Isokinetic Fatigue Test Is Associated With Anaerobic Work Capacity

    Science.gov (United States)

    Bosquet, Laurent; Gouadec, Kenan; Berryman, Nicolas; Duclos, Cyril; Gremeaux, Vincent; Croisier, Jean Louis

    2016-01-01

    The purpose of the study was to determine whether total work measured during a high intensity isokinetic fatigue test (TWFAT) could be considered as a valid measure of anaerobic work capacity (AWC), such as determined by total work measured during a Wingate Anaerobic Test (TWWAnT). Twenty well-trained cyclists performed 2 randomly ordered sessions involving a high intensity isokinetic fatigue test consisting in 30 reciprocal maximal concentric contractions of knee flexors and extensors at 180°·s-1, and a Wingate Anaerobic Test. We found that TWFAT of knee extensors was largely lower than TWWAnT (4151 ± 691 vs 22313 ± 2901 J, respectively, p knee flexors (2151 ± 540 J) was largely lower than TWWAnT (p knee flexors and knee extensors into a single measure (6302 ± 818 J) did not changed neither improved these observations. We still found a large difference with TWWAnT (p knee extensors could be considered as a valid measure of AWC, since both measure were highly associated. However, the mean difference between both measures and their 95% LoA were too large to warrant interchangeability. Key points Total work performed during a high intensity isokinetic fatigue test can be considered as a valid measure of anaerobic work capacity (as determined by total work performance during a 30-s Wingate anaerobic test). The 95% limits of agreement are two large to allow a direct comparison between both measures. In other words, it is not possible to estimate the magnitude of performance improvement during a 30-s Wingate anaerobic test from that observed during a high intensity isokinetic fatigue test. In addition to provide sport scientists and coaches with measures of peak torque and ratios between agonists and antagonists muscles in a perspective of injury prevention, isokinetic dynamometry can also be used in the physiological assessment of athletes. However, some precautions should be taken in the interpretation of data. PMID:26957935

  1. Design of a Fatigue Detection System for High-Speed Trains Based on Driver Vigilance Using a Wireless Wearable EEG

    Science.gov (United States)

    Zhang, Xiaoliang; Li, Jiali; Liu, Yugang; Zhang, Zutao; Wang, Zhuojun; Luo, Dianyuan; Zhou, Xiang; Zhu, Miankuan; Salman, Waleed; Hu, Guangdi; Wang, Chunbai

    2017-01-01

    The vigilance of the driver is important for railway safety, despite not being included in the safety management system (SMS) for high-speed train safety. In this paper, a novel fatigue detection system for high-speed train safety based on monitoring train driver vigilance using a wireless wearable electroencephalograph (EEG) is presented. This system is designed to detect whether the driver is drowsiness. The proposed system consists of three main parts: (1) a wireless wearable EEG collection; (2) train driver vigilance detection; and (3) early warning device for train driver. In the first part, an 8-channel wireless wearable brain-computer interface (BCI) device acquires the locomotive driver’s brain EEG signal comfortably under high-speed train-driving conditions. The recorded data are transmitted to a personal computer (PC) via Bluetooth. In the second step, a support vector machine (SVM) classification algorithm is implemented to determine the vigilance level using the Fast Fourier transform (FFT) to extract the EEG power spectrum density (PSD). In addition, an early warning device begins to work if fatigue is detected. The simulation and test results demonstrate the feasibility of the proposed fatigue detection system for high-speed train safety. PMID:28257073

  2. Design of a Fatigue Detection System for High-Speed Trains Based on Driver Vigilance Using a Wireless Wearable EEG

    Directory of Open Access Journals (Sweden)

    Xiaoliang Zhang

    2017-03-01

    Full Text Available The vigilance of the driver is important for railway safety, despite not being included in the safety management system (SMS for high-speed train safety. In this paper, a novel fatigue detection system for high-speed train safety based on monitoring train driver vigilance using a wireless wearable electroencephalograph (EEG is presented. This system is designed to detect whether the driver is drowsiness. The proposed system consists of three main parts: (1 a wireless wearable EEG collection; (2 train driver vigilance detection; and (3 early warning device for train driver. In the first part, an 8-channel wireless wearable brain-computer interface (BCI device acquires the locomotive driver’s brain EEG signal comfortably under high-speed train-driving conditions. The recorded data are transmitted to a personal computer (PC via Bluetooth. In the second step, a support vector machine (SVM classification algorithm is implemented to determine the vigilance level using the Fast Fourier transform (FFT to extract the EEG power spectrum density (PSD. In addition, an early warning device begins to work if fatigue is detected. The simulation and test results demonstrate the feasibility of the proposed fatigue detection system for high-speed train safety.

  3. Influence of high pressure hydrogen environment on tensile and fatigue properties of stainless steels at low temperatures

    Science.gov (United States)

    Ogata, T.

    2012-06-01

    Hydrogen environment embrittlement (HEE) of stainless steels in the environment of high pressure and low temperature hydrogen gas was evaluated using a very simple mechanical properties testing procedure. In the method, the high-pressure hydrogen environment is produced just inside the hole in the specimen. In this work, the effects of HEE on fatigue properties for austenitic stainless steels SUS304L and SUS316L were evaluated at 298 and 190 K. The effects of HEE on the tensile properties of higher strength stainless steels, such as strain-hardened 316, SUS630, and other alloys, SUH660 and Alloy 718 were also examined. The less effect of HEE on fatigue properties of SUS316L and tensile properties of strain-hardened 316 were observed compared with SUS304L and other steels at room temperature and 190 K.

  4. Radiosensitivity and cancer-related genes

    Energy Technology Data Exchange (ETDEWEB)

    Takahashi, Akihisa; Ohnishi, Takeo [Nara Medical Univ., Kashihara (Japan)

    1997-03-01

    The influence of several cancer-related genes, myc, fos, jun, ras, raf mos, cot, src, erbB, bcl-2, RB and p53, on radiosensitivity has been shown by tranfection studies. This review focuses on the functions of growth arrest, DNA repair and apoptosis regulated by these cancer-related genes. Resistance to apoptosis has emerged as a major category of radiation sensitivity. In the near future, it might be clear which of the cancer-related genes acts in an important role in apoptosis pathway after irradiation. In addition, there is no direct evidence in the activation of DNA repair during the cell cycle arrest. Therefore, identification of factors directly acting on radiation sensitivity will offer new strategies in cancer predictical assay using biopsied tumor specimens in radiotherapy. Further studies are must to be carried out for detection of common mutations in cancer-related genes for predictical assay and the potential for induction of apoptosis by radiotherapy and genetherapy. (author). 107 refs.

  5. High speed rails. Fatigue behaviour; Carriles para alta velocidad. Comportamiento en fatiga

    Energy Technology Data Exchange (ETDEWEB)

    Duart, J. M.; Pero-Sanz, J. A.; Verdeja, J. I.

    2005-07-01

    In recent years, passenger train speed and freight train load have increased to enhance efficiency of rail road transportation. These trends have increased the severity of rail service conditions, calling for rails with greater wear resistance, strength and fatigue behaviour. In the United Stated and Europe, track site weld rails are made entirely by aluminothermic process. This work describes the results of experimental study conducted on bending fatigue strength of plain rails and aluminothermic welded rails with preheating procedures (oxipropane and air-induced propane) approved by railways authorities. Compliance with the required fatigue strength shall be ascertained by 4 point pulsating bending test in accordance with European standards by aluminothermic welding in rails. The locati method, based in the empirical Miner's law about the cumulative damage on a fatigue tested material, allows, once known the Wohler curve of the welding process in use to settle the fatigue tensile limit at 50% with only one test. The values obtained at 2.10''6 cycles for plain rails (S{sub f}=353 MPa), oxipropane preheated aluminothermic weld rails (S{sub f}=225 MPa), and propane-air induced aluminothermic weld rails (S{sub f}=210 MPa) are very similar to those resulting from test method stated in the European Standard. From our point of view and due to its ease, speediness and savings, this is the most suitable test to check the quality and compare the aluminothermic processes in use. (Author) 15 refs.

  6. High-temperature fatigue in metals - A brief review of life prediction methods developed at the Lewis Research Center of NASA

    Science.gov (United States)

    Halford, G. R.

    1983-01-01

    The presentation focuses primarily on the progress we at NASA Lewis Research Center have made. The understanding of the phenomenological processes of high temperature fatigue of metals for the purpose of calculating lives of turbine engine hot section components is discussed. Improved understanding resulted in the development of accurate and physically correct life prediction methods such as Strain-Range partitioning for calculating creep fatigue interactions and the Double Linear Damage Rule for predicting potentially severe interactions between high and low cycle fatigue. Examples of other life prediction methods are also discussed. Previously announced in STAR as A83-12159

  7. Development of a probabilistic model for the prediction of fatigue life in the very high cycle fatigue (VHCF range based on inclusion population

    Directory of Open Access Journals (Sweden)

    Kolyshkin A.

    2014-06-01

    Full Text Available The VHCF behaviour of metallic materials containing microstructural defects such as non-metallic inclusions is determined by the size and distribution of the damage dominating defects. In the present paper, the size and location of about 60.000 inclusions measured on the longitudinal and transversal cross sections of AISI 304 sheet form a database for the probabilistic determination of failure-relevant inclusion distribution in fatigue specimens and their corresponding fatigue lifes. By applying the method of Murakami et al. the biggest measured inclusions were used in order to predict the size of failure-relevant inclusions in the fatigue specimens. The location of the crack initiating inclusions was defined based on the modeled inclusion population and the stress distribution in the fatigue specimen, using the probabilistic Monte Carlo framework. Reasonable agreement was obtained between modeling and experimental results.

  8. Influence of different breathing frequencies on the severity of inspiratory muscle fatigue induced by high-intensity front crawl swimming.

    Science.gov (United States)

    Jakovljevic, Djordje G; McConnell, Alison K

    2009-07-01

    The aim of the present study was to assess the influence of 2 different breathing frequencies on the magnitude of inspiratory muscle fatigue after high-intensity front crawl swimming. The influence of different breathing frequencies on postexercise blood lactate ([La]) and heart rate (HR) was also examined. Ten collegiate swimmers performed 2 x 200-m front crawl swims at 90% of race pace with the following breathing frequencies: 1) 1 breath every second stroke (B2), and 2) 1 breath every fourth stroke (B4). Maximal inspiratory pressure (PImax) was measured at the mouth from residual volume before (baseline) and after swimming, in a standing position. The HR and [La] were assessed at rest and immediately at the cessation of swimming. The PImax decreased by 21% after B4 and by 11% after B2 compared with baseline (p inspiratory muscle fatigue after high-intensity swimming. Inspiratory muscle fatigue is, however, greater when breathing frequency is reduced during high-intensity front crawl swimming. Respiratory muscle training should be used to improve respiratory muscle strength and endurance in swimmers.

  9. The potential significance of microalloying with niobium in governing very high cycle fatigue behavior of bainite/martensite multiphase steels

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, P., E-mail: zhaoping12@mails.tsinghua.edu.cn [Key Laboratory of Advanced Materials of Ministry of Education, School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Beijing Iron & Steel Research Institute, Special Steel Institute, Beijing 100081 (China); Cheng, C.; Gao, G.; Hui, W. [Materials Science & Engineering Research Center, Beijing Jiaotong University, Beijing 100044 (China); Misra, R.D.K., E-mail: dmisra2@utep.edu [Laboratory for Excellence in Advanced Steel Research, Department of Metallurgical, Materials and Biomedical Engineering, University of Texas, El Paso 500 W. University Avenue, El Paso, TX 79968-0520 (United States); Bai, B.; Weng, Y. [Key Laboratory of Advanced Materials of Ministry of Education, School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China)

    2016-01-05

    We elucidate here the effect of microalloying with niobium (Nb) on very high cycle fatigue (VHCF) behavior in high-strength C–Mn–Si–Cr bainite/martensite (B/M) multiphase steels studied through ultrasonic fatigue testing. The tensile strength (R{sub m}) and fatigue limit strength after 10{sup 9} cycles (σ{sub w9}) and in the non-failure condition of the steel microalloyed with Nb were 1640 MPa and 900 MPa, respectively. Thus, the value of σ{sub w9}/R{sub m} exceeded in comparison to conventional steels and was approximate 0.55. Three types of failure modes were observed in Nb-bearing steels depending on the surface condition, inclusion, and the matrix microstructure, i.e., surface defect-induced failure mode (S-mode), inclusion-induced failure mode (I-mode), and non-inclusion induced failure mode (N-mode). Only two failure modes were observed in Nb-free steels, the S-mode and the N-mode. The study clearly suggests that Nb had a distinct effect on the VHCF properties of B/M steels. The VHCF limit of Nb-bearing steel was enhanced by 200 MPa because of refinement of the microstructure and pinning of dislocations by randomly distributed nanometer-sized Nb(C, N) precipitates. It is underscored that microalloying with Nb is a potential approach to enhance VHCF properties in advanced high-strength steels.

  10. Changes in mean cerebral blood flow velocity during cognitive task-induced cerebral fatigue in high performance fighter pilots

    Institute of Scientific and Technical Information of China (English)

    Yongsheng Chen

    2008-01-01

    BACKGROUND: Several studies have demonstrated that sustained cognitive tasks can induce cognitive fatigue and that the mean cerebral blood flow velocity changes in some cerebral regions during cerebral fatigue. OBJECTIVE: To dynamically monitor the changes in mean cerebral blood flow velocity in different brain regions of high performance fighter pilots during mental arithmetic tasks and consecutive performance tasks. DESIGN, TIME AND SETTING: The present neurophysiological trial, based on controlled observation, was performed at the Laboratory of Neurophysiology, Institute of Aviation Medicine, Air Force of China between January 2003 and December 2005. PARTICIPANTS: Forty-five males, high performance fighter pilots, averaging (27.6 ± 2.5) years, were recruited for this study. METHODS: The mean cerebral blood flow velocity in the anterior cerebral artery, middle cerebral artery, and posterior cerebral artery of subjects was dynamically tested using transcranial Doppler during 5- hour mental arithmetic tasks and during 5- hour consecutive performance tasks. The neurobehavioral ability index was analyzed throughout each trial according to the number of correct responses, false responses, and lost responses. Simultaneously, cerebral cognitive fatigue-induced lethargy was assessed by the Stanford Sleepiness Scale. MAIN OUTCOME MEASURES: Changes in mean cerebral blood flow velocity in the anterior cerebral artery, middle cerebral artery, and posterior cerebral artery; neurobehavioral ability index of mental arithmetic and consecutive performance tasks; Stanford Sleepiness Scale scores. RESULTS: During mental arithmetic tasks, the mean cerebral blood flow velocity in the anterior cerebral artery increased during hour 2 and decreased after hour 4. There was no significant change in mean cerebral blood flow velocity in the middle cerebral artery and posterior cerebral artery. During hour 4, cerebral cognitive fatigue was observed and, simultaneously, Stanford Sleepiness

  11. Fatigue fracture of cutter blade made of high-speed steel

    Directory of Open Access Journals (Sweden)

    Beata Letkowska

    2015-04-01

    Full Text Available The quality of the surface of cyclically loaded components is very important. Many observations confirm that the root cause of the micro cracks (causing the fatigue fracture are primarily a surface's defects appearing during production process. These surface defects can be also caused by engraving processes used to perform identification marks. This paper presents the failure analysis of broken blade of the cutter Ku 500VX. The blade was subject of standard metallographic examination, hardness measurements, fractography analysis and metallographic studies using stereoscopic, light and scanning electron microscopes. The damage of the blade was caused by changes of the structure (formation of the brittle micro dendritic structure that occurred during manual electric engraving process when the material was heated till its melting point. As a result the stresses occurred in surface what provided to micro cracking and to propagate the fatigue fracture. The origin of this fatigue fracture was in the place where the inscription was made.

  12. High-accuracy CFD prediction methods for fluid and structure temperature fluctuations at T-junction for thermal fatigue evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Qian, Shaoxiang, E-mail: qian.shaoxiang@jgc.com [EN Technology Center, Process Technology Division, JGC Corporation, 2-3-1 Minato Mirai, Nishi-ku, Yokohama 220-6001 (Japan); Kanamaru, Shinichiro [EN Technology Center, Process Technology Division, JGC Corporation, 2-3-1 Minato Mirai, Nishi-ku, Yokohama 220-6001 (Japan); Kasahara, Naoto [Nuclear Engineering and Management, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan)

    2015-07-15

    Highlights: • Numerical methods for accurate prediction of thermal loading were proposed. • Predicted fluid temperature fluctuation (FTF) intensity is close to the experiment. • Predicted structure temperature fluctuation (STF) range is close to the experiment. • Predicted peak frequencies of FTF and STF also agree well with the experiment. • CFD results show the proposed numerical methods are of sufficiently high accuracy. - Abstract: Temperature fluctuations generated by the mixing of hot and cold fluids at a T-junction, which is widely used in nuclear power and process plants, can cause thermal fatigue failure. The conventional methods for evaluating thermal fatigue tend to provide insufficient accuracy, because they were developed based on limited experimental data and a simplified one-dimensional finite element analysis (FEA). CFD/FEA coupling analysis is expected as a useful tool for the more accurate evaluation of thermal fatigue. The present paper aims to verify the accuracy of proposed numerical methods of simulating fluid and structure temperature fluctuations at a T-junction for thermal fatigue evaluation. The dynamic Smagorinsky model (DSM) is used for large eddy simulation (LES) sub-grid scale (SGS) turbulence model, and a hybrid scheme (HS) is adopted for the calculation of convective terms in the governing equations. Also, heat transfer between fluid and structure is calculated directly through thermal conduction by creating a mesh with near wall resolution (NWR) by allocating grid points within the thermal boundary sub-layer. The simulation results show that the distribution of fluid temperature fluctuation intensity and the range of structure temperature fluctuation are remarkably close to the experimental results. Moreover, the peak frequencies of power spectrum density (PSD) of both fluid and structure temperature fluctuations also agree well with the experimental results. Therefore, the numerical methods used in the present paper are

  13. Very high cycle regime fatigue of thin walled tubes made from austenitic stainless steel

    DEFF Research Database (Denmark)

    Carstensen, J.V.; Mayer, H.; Brøndsted, P.

    2002-01-01

    Fatigue life data of cold worked tubes (diameter 4 mm, wall thicknesses 0.25 and 0.30 mm) of an austenitic stainless steel, AISI 904 L, were measured in the regime ranging from 2 × 105 to 1010 cycles to failure. The influence of the loading frequency was investigated as data were obtained...... in conventional rotating bending at 160 and 200 Hz and in ultrasonic axial loading at 20 kHz. Above 5 × 106 cycles the fatigue lifetimes found with both methods were comparable. The results show that the slope of the S–N curve significantly decreases beyond 108 cycles. Fracture surfaces were examined using...

  14. Thermal Fatigue Behaviour of Co-Based Alloy Coating Obtained by Laser Surface Melt-Casting on High Temperature Alloy

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A thermal fatigue behaviour of C o-based alloy coating obtained by laser surface melt-casting on the high tempe rature alloy GH33 was studied. The results show that after each time of thermal cycling, the final residual stress was formed in the melt-casting layer which is attributed to the thermal stress and structural stress. Through the first 50 times of thermal cycling, the morphology of coating still inherits the laser casting one, but the dendrites get bigger; After the second 50 times of thermal cycling, corrosion pits emerge from coating, and mostly in the places where coating and substrate meet. The fatigue damage type of coating belongs to stress corrosi on.

  15. Simulation of Delamination Propagation in Composites Under High-Cycle Fatigue by Means of Cohesive-Zone Models

    Science.gov (United States)

    Turon, Albert; Costa, Josep; Camanho, Pedro P.; Davila, Carlos G.

    2006-01-01

    A damage model for the simulation of delamination propagation under high-cycle fatigue loading is proposed. The basis for the formulation is a cohesive law that links fracture and damage mechanics to establish the evolution of the damage variable in terms of the crack growth rate dA/dN. The damage state is obtained as a function of the loading conditions as well as the experimentally-determined coefficients of the Paris Law crack propagation rates for the material. It is shown that by using the constitutive fatigue damage model in a structural analysis, experimental results can be reproduced without the need of additional model-specific curve-fitting parameters.

  16. AISI/DOE Technology Roadmap Program: Characterization of Fatigue and Crash Performance of New Generation High Strength Steels for Automotive Applications

    Energy Technology Data Exchange (ETDEWEB)

    Brenda Yan; Dennis Urban

    2003-04-21

    A 2-year project (2001-2002) to generate fatigue and high strain data for a new generation of high strength steels (HSS) has been completed in December 2002. The project tested eleven steel grades, including Dual Phase (DP) steels, Transformation-Induced Plasticity (TRIP) steels, Bake Hardenable (BH) steels, and conventional High Strength Low Alloy (HSLA) steels. All of these steels are of great interest in automotive industry due to the potential benefit in weight reduction, improved fuel economy, enhanced crash energy management and total system cost savings. Fatigue behavior includes strain controlled fatigue data notch sensitivity for high strength steels. High strain rate behavior includes stress-strain data for strain rates from 0.001/s to 1000/s, which are considered the important strain rate ranges for crash event. The steels were tested in two phases, seven were tested in Phase 1 and the remaining steels were tested in Phase. In a addition to the fatigue data and high st rain rate data generated for the steels studied in the project, analyses of the testing results revealed that Advanced High Strength Steels (AHSS) exhibit significantly higher fatigue strength and crash energy absorption capability than conventional HSS. TRIP steels exhibit exceptionally better fatigue strength than steels of similar tensile strength but different microstructure, for conditions both with or without notches present

  17. The slow component of pulmonary O2 uptake accompanies peripheral muscle fatigue during high-intensity exercise.

    Science.gov (United States)

    Keir, Daniel A; Copithorne, David B; Hodgson, Michael D; Pogliaghi, Silvia; Rice, Charles L; Kowalchuk, John M

    2016-08-01

    During constant-power output (PO) exercise above lactate threshold (LT), pulmonary O2 uptake (V̇o2 p) features a developing slow component (V̇o2 pSC). This progressive increase in O2 cost of exercise is suggested to be related to the effects of muscle fatigue development. We hypothesized that peripheral muscle fatigue as assessed by contractile impairment would be associated with the V̇o2 pSC Eleven healthy men were recruited to perform four constant-PO tests at an intensity corresponding to ∼Δ60 (very heavy, VH) where Δ is 60% of the difference between LT and peak V̇o2 p The VH exercise was completed for each of 3, 8, 13, and 18 min (i.e., VH3, VH8, VH13, VH18) with each preceded by 3 min of cycling at 20 W. Peripheral muscle fatigue was assessed via pre- vs. postexercise measurements of quadriceps torque in response to brief trains of electrical stimulation delivered at low (10 Hz) and high (50 Hz) frequencies. During exercise, breath-by-breath V̇o2 p was measured by mass spectrometry and volume turbine. The magnitude of V̇o2 pSC increased (P low-to-high frequency (10/50 Hz) response was reduced (P < 0.05) at VH3 (-12 ± 9%) and further reduced (P < 0.05) at VH8 (-25 ± 11%), VH13 (-42 ± 19%), and VH18 (-46 ± 16%), mirroring the temporal pattern of V̇o2 pSC development. The reduction in 10/50 Hz ratio was correlated (P < 0.001, r(2) = 0.69) with V̇o2 pSC amplitude. The temporal and quantitative association of decrements in muscle torque production and V̇o2 pSC suggest a common physiological mechanism between skeletal muscle fatigue and loss of muscle efficiency.

  18. Adenosine-5'-triphosphate (ATP supplementation improves low peak muscle torque and torque fatigue during repeated high intensity exercise sets

    Directory of Open Access Journals (Sweden)

    Rathmacher John A

    2012-10-01

    Full Text Available Abstract Background Intracellular concentrations of adenosine-5’-triphosphate (ATP are many times greater than extracellular concentrations (1–10 mM versus 10–100 nM, respectively and cellular release of ATP is tightly controlled. Transient rises in extracellular ATP and its metabolite adenosine have important signaling roles; and acting through purinergic receptors, can increase blood flow and oxygenation of tissues; and act as neurotransmitters. Increased blood flow not only increases substrate availability but may also aid in recovery through removal of metabolic waste products allowing muscles to accomplish more work with less fatigue. The objective of the present study was to determine if supplemental ATP would improve muscle torque, power, work, or fatigue during repeated bouts of high intensity resistance exercise. Methods Sixteen participants (8 male and 8 female; ages: 21–34 years were enrolled in a double-blinded, placebo-controlled study using a crossover design. The participants received either supplemental ATP (400 mg/d divided into 2 daily doses or placebo for 15 d. After an overnight fast, participants underwent strength and fatigue testing, consisting of 3 sets of 50 maximal knee extensions performed on a Biodex® leg dynamometer. Results No differences were detected in high peak torque, power, or total work with ATP supplementation; however, low peak torque in set 2 was significantly improved (p Conclusions Supplementation with 400 mg ATP/d for 15 days tended to reduce muscle fatigue and improved a participant’s ability to maintain a higher force output at the end of an exhaustive exercise bout.

  19. The Effect of High RAP and High Asphalt Binder Content on the Dynamic Modulus and Fatigue Resistance of Asphalt Concrete

    OpenAIRE

    Tomlinson, Christopher

    2013-01-01

    This thesis investigates the effects of using various percentages of RAP and asphalt binder contents on the dynamic modulus and fatigue resistance of asphalt concrete. Two RAP percentages (20% and 40%) and three binder percentages (plant-mixed, plant-mixed + 0.5%, and plant-mixed + 1.0%) were evaluated. A Superpave gyratory compactor and an asphalt vibratory compactor were used to prepare dynamic modulus samples and fatigue beam samples at 7% air voids. Three replicate samples for each percen...

  20. High Sensitive Methods for Health Monitoring of Compressor Blades and Fatigue Detection

    Directory of Open Access Journals (Sweden)

    Mirosław Witoś

    2013-01-01

    Full Text Available The diagnostic and research aspects of compressor blade fatigue detection have been elaborated in the paper. The real maintenance and overhaul problems and characteristic of different modes of metal blade fatigue (LCF, HCF, and VHCF have been presented. The polycrystalline defects and impurities influencing the fatigue, along with their related surface finish techniques, are taken into account. The three experimental methods of structural health assessment are considered. The metal magnetic memory (MMM, experimental modal analysis (EMA and tip timing (TTM methods provide information on the damage of diagnosed objects, for example, compressor blades. Early damage symptoms, that is, magnetic and modal properties of material strengthening and weakening phases (change of local dislocation density and grain diameter, increase of structural and magnetic anisotropy, have been described. It has been proven that the shape of resonance characteristic gives abilities to determine if fatigue or a blade crack is concerned. The capabilities of the methods for steel and titanium alloy blades have been illustrated in examples from active and passive experiments. In the conclusion, the MMM, EMA, and TTM have been verified, and the potential for reliable diagnosis of the compressor blades using this method has been confirmed.

  1. Fatigue of concrete under compression: Database and proposal for high strength concrete

    NARCIS (Netherlands)

    Lantsoght, E.O.L.

    2014-01-01

    The compressive strength of concrete decreases as an element is subjected to cycles of loading. In a typical fatigue test for the concrete compressive strength, a concrete specimen (typically a cylinder) is loaded between a lower and upper stress limit. These limits are expressed as a fraction of th

  2. High sensitive methods for health monitoring of compressor blades and fatigue detection.

    Science.gov (United States)

    Witoś, Mirosław

    2013-01-01

    The diagnostic and research aspects of compressor blade fatigue detection have been elaborated in the paper. The real maintenance and overhaul problems and characteristic of different modes of metal blade fatigue (LCF, HCF, and VHCF) have been presented. The polycrystalline defects and impurities influencing the fatigue, along with their related surface finish techniques, are taken into account. The three experimental methods of structural health assessment are considered. The metal magnetic memory (MMM), experimental modal analysis (EMA) and tip timing (TTM) methods provide information on the damage of diagnosed objects, for example, compressor blades. Early damage symptoms, that is, magnetic and modal properties of material strengthening and weakening phases (change of local dislocation density and grain diameter, increase of structural and magnetic anisotropy), have been described. It has been proven that the shape of resonance characteristic gives abilities to determine if fatigue or a blade crack is concerned. The capabilities of the methods for steel and titanium alloy blades have been illustrated in examples from active and passive experiments. In the conclusion, the MMM, EMA, and TTM have been verified, and the potential for reliable diagnosis of the compressor blades using this method has been confirmed.

  3. Fatigue of concrete under compression: Database and proposal for high strength concrete

    NARCIS (Netherlands)

    Lantsoght, E.O.L.

    2014-01-01

    The compressive strength of concrete decreases as an element is subjected to cycles of loading. In a typical fatigue test for the concrete compressive strength, a concrete specimen (typically a cylinder) is loaded between a lower and upper stress limit. These limits are expressed as a fraction of

  4. A new methodology for automating acoustic emission detection of metallic fatigue fractures in highly demanding aerospace environments: An overview

    Science.gov (United States)

    Holford, Karen M.; Eaton, Mark J.; Hensman, James J.; Pullin, Rhys; Evans, Sam L.; Dervilis, Nikolaos; Worden, Keith

    2017-04-01

    The acoustic emission (AE) phenomenon has many attributes that make it desirable as a structural health monitoring or non-destructive testing technique, including the capability to continuously and globally monitor large structures using a sparse sensor array and with no dependency on defect size. However, AE monitoring is yet to fulfil its true potential, due mainly to limitations in location accuracy and signal characterisation that often arise in complex structures with high levels of background noise. Furthermore, the technique has been criticised for a lack of quantitative results and the large amount of operator interpretation required during data analysis. This paper begins by introducing the challenges faced in developing an AE based structural health monitoring system and then gives a review of previous progress made in addresing these challenges. Subsequently an overview of a novel methodology for automatic detection of fatigue fractures in complex geometries and noisy environments is presented, which combines a number of signal processing techniques to address the current limitations of AE monitoring. The technique was developed for monitoring metallic landing gear components during pre-flight certification testing and results are presented from a full-scale steel landing gear component undergoing fatigue loading. Fracture onset was successfully identify automatically at 49,000 fatigue cycles prior to final failure (validated by the use of dye penetrant inspection) and the fracture position was located to within 10 mm of the actual location.

  5. Jet lag and travel fatigue: a comprehensive management plan for sport medicine physicians and high-performance support teams.

    Science.gov (United States)

    Samuels, Charles H

    2012-05-01

    The impact of transcontinental travel and high-volume travel on athletes can result in physiologic disturbances and a complicated set of physical symptoms. Jet lag and travel fatigue have been identified by athletes, athletic trainers, coaches, and physicians as important but challenging problems that could benefit from practical solutions. Currently, there is a culture of disregard and lack of knowledge regarding the negative effects of jet lag and travel fatigue on the athlete's well-being and performance. In addition, the key physiologic metric (determination of the human circadian phase) that guides jet lag treatment interventions is elusive and thus limits evidence-based therapeutic advice. A better understanding of preflight, in-flight, and postflight management options, such as use of melatonin or the judicious application of sedatives, is important for the sports clinician to help athletes limit fatigue symptoms and maintain optimal performance. The purpose of this article was to provide a practical applied method of implementing a travel management program for athletic teams.

  6. HIGH TEMPERATURE TIME DEPENDENT UNIAXIAL AND MULTIAXIAL FATIGUE DAMAGE MODEL%高温时间相关单多轴疲劳损伤模型

    Institute of Scientific and Technical Information of China (English)

    孙国芹; 尚德广; 李承山

    2009-01-01

    针对高温疲劳中蠕变和氧化因素的影响,提出高温循环加载下时间相关疲劳损伤模型.根据材料高温疲劳微观观察和疲劳过程,充分考虑拉压应变率和循环周期不同而造成的不同损伤,提出高温影响折算时间的计算方法.结合损伤理论和高温对疲劳损伤的影响,把无保载时间的高温疲劳损伤分为纯疲劳损伤、时间相关损伤和交互损伤,损伤模型经高温2.25Cr-1Mo钢单多轴疲劳试验验证,结果表明,误差在两个因子之内.%Time dependent fatigue damage model under cyclic loading was proposed by considering the effect of creep and oxidation at high temperature on the fatigue damage. The high temperature fatigue damage without holding time was divided into pure fatigue damage, damage caused by the time dependent factors and interactive damage to combine effect of high temperature to fatigue damage with the damage rule. The converting time influenced by high temperature was proposed according to tension-compression strain rate and different cycle period based on the SEM(scanning electron microscope) observation of the fatigue rupture surface and fatigue process. The results for 2.25Cr-1Mo steel tests under uniaxial and multiaxial high temperature fatigue showed an error within a factor of two.

  7. MODELS OF FATIGUE LIFE CURVES IN FATIGUE LIFE CALCULATIONS OF MACHINE ELEMENTS – EXAMPLES OF RESEARCH

    Directory of Open Access Journals (Sweden)

    Grzegorz SZALA

    2014-03-01

    Full Text Available In the paper there was attempted to analyse models of fatigue life curves possible to apply in calculations of fatigue life of machine elements. The analysis was limited to fatigue life curves in stress approach enabling cyclic stresses from the range of low cycle fatigue (LCF, high cycle fatigue (HCF, fatigue limit (FL and giga cycle fatigue (GCF appearing in the loading spectrum at the same time. Chosen models of the analysed fatigue live curves will be illustrated with test results of steel and aluminium alloys.

  8. Evaluation of the Effect of Surface Finish on High-Cycle Fatigue of SLM-IN718

    Science.gov (United States)

    Lambert, D. M.

    2016-01-01

    The surface finish of parts produced by additive manufacturing processes is much rougher than the surface finish generated by machining processes, and a rougher surface can reduce the fatigue strength of a part. This paper discusses an effort to quantify that reduction of strength in high-cycle fatigue for selective laser melt (SLM) coupons. A high-cycle fatigue (HCF) knockdown factor was estimated for Inconel 718, manufactured with the SLM process. This factor is the percentage reduction from the maximum stress in fatigue for low-stress ground (LSG) specimens to the maximum stress of those left with the original surface condition at the same fatigue life. Specimens were provided by a number of vendors, free to use their "best practice"; only one heat treat condition was considered; and several test temperatures were characterized, including room temperature, 800F, 1000F, and 1200F. The 1000F data had a large variance, and was omitted from consideration in this document. A first method used linear approximations extracted from the graphs, and only where data was available for both. A recommended knockdown factor of the as-built surface condition (average roughness of approximately 245 micro-inches/inch) versus low-stress ground condition (roughness no more than 4 micro-inches/inch) was established at approximately 1/3 or 33%. This is to say that for the as-built surface condition, a maximum stress of 2/3 of the stress for LSG can be expected to produce a similar life in the as-built surface condition. In this first evaluation, the knockdown factor did not appear to be a function of temperature. A second approach, the "KP method", incorporated the surface finish measure into a new parameter termed the pseudo-stress intensity factor, Kp, which was formulated to be similar to the fracture mechanics stress intensity factor. Using Kp, the variance seemed to be reduced across all sources, and knockdown factors were estimated using Kp over the range where data occurred. A

  9. Visual Fatigue Induced by Viewing a Tablet Computer with a High-resolution Display.

    Science.gov (United States)

    Kim, Dong Ju; Lim, Chi Yeon; Gu, Namyi; Park, Choul Yong

    2017-07-18

    In the present study, the visual discomfort induced by smart mobile devices was assessed in normal and healthy adults. Fifty-nine volunteers (age, 38.16 ± 10.23 years; male : female = 19 : 40) were exposed to tablet computer screen stimuli (iPad Air, Apple Inc.) for 1 hour. Participants watched a movie or played a computer game on the tablet computer. Visual fatigue and discomfort were assessed using an asthenopia questionnaire, tear film break-up time, and total ocular wavefront aberration before and after viewing smart mobile devices. Based on the questionnaire, viewing smart mobile devices for 1 hour significantly increased mean total asthenopia score from 19.59 ± 8.58 to 22.68 ± 9.39 (p Visual fatigue and discomfort were significantly induced by viewing smart mobile devices, even though the devices were equipped with state-of-the-art display technology.

  10. Dynamic speckle interferometry of high-cycle material fatigue: Theory and some experiments

    Science.gov (United States)

    Vladimirov, A. P.

    2016-06-01

    The objective of this paper was theoretical analysis of speckle dynamics in the image plane of a thin transparent object. It was suggested that speckle dynamics develops in simultaneous periodic motion of the sample, micro- and macro-variations of its refraction index and its translational motion. The results of the theory were contrasted with the data obtained in the fatigue tests with transparent object.

  11. High-strain fiber bragg gratings for structural fatigue testing of military aircraft

    Science.gov (United States)

    Davis, Claire; Tejedor, Silvia; Grabovac, Ivan; Kopczyk, James; Nuyens, Travis

    2012-09-01

    This paper reports on an experimental program of work which investigates the reliability, durability, and packaging of fiber Bragg gratings (FBGs) for application as distributed strain sensors during structural fatigue testing of military platforms. The influence of the FBG fabrication process on sensor reliability is investigated. In addition, methodologies for broad-area packaging and surface-mounting of FBG sensing arrays to defense platforms are developed and tested.

  12. Fatigue crack growth from handling surface anomalies in a nickel based superalloy at high temperature

    Directory of Open Access Journals (Sweden)

    Gourdin Stéphane

    2014-01-01

    Full Text Available Aircraft engine manufacturers have to demonstrate that handling surface anomalies in sensitive areas of discs are not critical for in-service life of a component. Currently, the models used consider anomalies as long cracks propagating from the first cycle, which introduces a certain degree of conservatism when calculating the fatigue life of surface flaws. Preliminary studies have shown that the first stages of crack propagation from surface anomalies are responsible for the conservative results. Thus, the aim of the study is to characterize the crack propagation from typical surface anomalies and to establish a new crack growth model, which can account for the micro-propagation stage. To separate the effects of the geometry of the anomalies and the residual stress state after introduction of the surface flaws, two V-type anomalies are studied: scratches and dents. Different studies have shown that the residual stresses beneath the anomalies seem to control the fatigue life of samples exhibiting scratches and dents. In order to monitor the crack micro-propagation, a direct current potential drop technique, coupled with heat tints is used during fatigue tests at elevated temperature. Thermal treatments releasing the residual stresses are also used to decouple the effect of crack morphology and residual stresses.

  13. Fatigue behavior of highly porous titanium produced by powder metallurgy with temporary space holders

    Energy Technology Data Exchange (ETDEWEB)

    Özbilen, Sedat [Forschungszentrum Jülich, Institute of Energy and Climate Research (IEK), 52425 Jülich (Germany); Gazi University, Faculty of Technology, Department of Metallurgical and Materials Engineering, Teknikokullar, Ankara (Turkey); Liebert, Daniela [Forschungszentrum Jülich, Institute of Energy and Climate Research (IEK), 52425 Jülich (Germany); Beck, Tilmann [Forschungszentrum Jülich, Institute of Energy and Climate Research (IEK), 52425 Jülich (Germany); University of Kaiserslautern, Lehrstuhl für Werkstoffkunde (WKK), D-67663 Kaiserslautern (Germany); Bram, Martin, E-mail: m.bram@fz-juelich.de [Forschungszentrum Jülich, Institute of Energy and Climate Research (IEK), 52425 Jülich (Germany)

    2016-03-01

    Porous titanium cylinders were produced with a constant amount of temporary space holder (70 vol.%). Different interstitial contents were achieved by varying the starting powders (HDH vs. gas atomized) and manufacturing method (cold compaction without organic binders vs. warm compaction of MIM feedstocks). Interstitial contents (O, C, and N) as a function of manufacturing were measured by chemical analysis. Samples contained 0.34–0.58 wt.% oxygen, which was found to have the greatest effect on mechanical properties. Quasi-static mechanical tests under compression at low strain rate were used for reference and to define parameters for cyclic compression tests. Not unexpectedly, increased oxygen content increased the yield strength of the porous titanium. Cyclic compression fatigue tests were conducted using sinusoidal loading in a servo-hydraulic testing machine. Increased oxygen content was concomitant with embrittlement of the titanium matrix, resulting in significant reduction of compression cycles before failure. For samples with 0.34 wt.% oxygen, R, σ{sub min} and σ{sub max} were varied systematically to estimate the fatigue limit (~ 4 million cycles). Microstructural changes induced by cyclic loading were then characterized by optical microscopy, SEM and EBSD. - Highlights: • Systematic variation of the oxygen content from 0.34 to 0.58 wt.%. • Systematic study of the relationship between fatigue limit and oxygen content. • Critical oxygen equivalent seems to be 0.35 wt.% to avoid embrittlement. • Identification of the failure modes by light microscopy, SEM and EBSD.

  14. Effects of stress ratio on the temperature-dependent high-cycle fatigue properties of alloy steels

    Institute of Scientific and Technical Information of China (English)

    Zhi-yang L; Ao-shuang Wan; Jun-jiang Xiong; Kuang Li; Jian-zhong Liu

    2016-01-01

    This paper addresses the effects of stress ratio on the temperature-dependent high-cycle fatigue (HCF) properties of alloy steels 2CrMo and 9CrCo, which suffer from substantial vibrational loading at small stress amplitude, high stress ratio, and high frequency in the high-temperature environments in which they function as blade and rotor spindle materials in advanced gas or steam turbine engines. Fatigue tests were performed on alloy steels 2CrMo and 9CrCo subjected to constant-amplitude loading at four stress ratios and at four and three temperatures, respectively, to determine their temperature-dependent HCF properties. The interaction mechanisms between high temperature and stress ratio were deduced and compared with each other on the basis of the results of fractographic analysis. A phenomenological model was developed to evaluate the effects of stress ratio on the temperature-dependent HCF properties of alloy steels 2CrMo and 9CrCo. Good correlation was achieved between the predictions and actual experiments, demonstrating the practical and effective use of the proposed method.

  15. Effects of stress ratio on the temperature-dependent high-cycle fatigue properties of alloy steels

    Science.gov (United States)

    Lü, Zhi-yang; Wan, Ao-shuang; Xiong, Jun-jiang; Li, Kuang; Liu, Jian-zhong

    2016-12-01

    This paper addresses the effects of stress ratio on the temperature-dependent high-cycle fatigue (HCF) properties of alloy steels 2CrMo and 9CrCo, which suffer from substantial vibrational loading at small stress amplitude, high stress ratio, and high frequency in the high-temperature environments in which they function as blade and rotor spindle materials in advanced gas or steam turbine engines. Fatigue tests were performed on alloy steels 2CrMo and 9CrCo subjected to constant-amplitude loading at four stress ratios and at four and three temperatures, respectively, to determine their temperature-dependent HCF properties. The interaction mechanisms between high temperature and stress ratio were deduced and compared with each other on the basis of the results of fractographic analysis. A phenomenological model was developed to evaluate the effects of stress ratio on the temperature-dependent HCF properties of alloy steels 2CrMo and 9CrCo. Good correlation was achieved between the predictions and actual experiments, demonstrating the practical and effective use of the proposed method.

  16. Spinal cord stimulation for cancer-related pain in adults.

    Science.gov (United States)

    Lihua, Peng; Su, Min; Zejun, Zhou; Ke, Wei; Bennett, Michael I

    2013-02-28

    Cancer-related pain places a heavy burden on public health with related high expenditure. Severe pain is associated with a decreased quality of life in patients with cancer. A significant proportion of patients with cancer-related pain are under-treated.There is a need for more effective control of cancer-related pain. Spinal cord stimulation (SCS) may have a role in pain management. The effectiveness and safety of SCS for patients with cancer-related pain is currently unknown. This systematic review evaluated the effectiveness of SCS for cancer-related pain compared with standard care using conventional analgesic medication. We also appraised risk and potential adverse events associated with the use of SCS. We searched the following bibliographic databases in order to identify relevant studies: the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Libary (from inception to 2012, Issue 6); MEDLINE; EMBASE; and CBM (Chinese Biomedical Database) (from inception to July, 2012). We also handsearched relevant journals. We planned to include randomised controlled trials (RCTs) that directly compared SCS with other interventions with regards to the effectiveness of pain management. We also planned to include cross-over trials that compared SCS with another treatment. We planned to identify non-randomised controlled trials but these would only be included if no RCTs could be found. The initial search strategy yielded 430 articles. By scrutinising titles and abstracts, we found 412 articles irrelevant to the analytical purpose of this systematic review due to different scopes of diseases or different methods of intervention (intrathecal infusion system; oral medication) or aims other than pain control (spinal cord function monitoring, bladder function restoration or amelioration of organ metabolism). The remaining 18 trials were reviewed as full manuscripts. No RCTs were identified. Fourteen sporadic case reports and review articles were excluded and

  17. Fatigue crack growth from handling surface anomalies in a Nickel based superalloy at high temperature

    Directory of Open Access Journals (Sweden)

    Gourdin Stéphane

    2014-06-01

    Full Text Available Aircraft engine manufacturers have to demonstrate that handling surface anomalies in sensible areas of discs are not critical for in-service life of a component. Currently, the models used consider anomalies as long cracks propagating from the first cycle, which introduce a certain degree of conservatism when calculating the fatigue life of surface flaws. Preliminary studies have shown that the first stages of crack propagation from surface anomalies are responsible for the conservative results. Thus, the aim of the study is to characterize the crack propagation from typical surface anomalies and to establish a new crack growth model, which can account for the micro-propagation stage.

  18. Characterization of high temperature tensile and creep–fatigue properties of Alloy 800H for intermediate heat exchanger components of (V)HTRs

    Energy Technology Data Exchange (ETDEWEB)

    Kolluri, M., E-mail: kolluri@nrg.eu; Pierick, P. ten, E-mail: tenpierick@nrg.eu; Bakker, T., E-mail: t.bakker@nrg.eu

    2015-04-01

    Highlights: • High temperature tensile, creep–fatigue (C–F) properties of Alloy 800H are studied. • Strength and uniform elongation properties at 800 °C are much lower than RT values. • Strong influence of hold time and Δε{sub tot} on low cycle fatigue life was observed. • The total allowable C–F damage (D) at 800 °C decreases with the decreasing Δε{sub tot}. • Synergetic effect of C–F interactions showed stronger effect at lower Δε{sub tot} values. - Abstract: Alloy 800H is considered as a candidate material for intermediate heat exchanger (IHX) components of (very) high temperature reactors (V)HTRs. Qualification of the this alloy for the aforementioned nuclear applications requires understanding of its high temperature tensile, low-cycle fatigue behavior and creep–fatigue interactions because the IHX components suffer from combined creep–fatigue loadings resulting from thermally induced strain cycles associated with start-up and shutdown cycles. To this end, in this paper, the tensile properties of the Alloy 800H base and tungsten inert gas (TIG) welded materials are studied at three different temperatures, room temperature 21, 700 and 800 °C. Low cycle fatigue (LCF) behavior of the base material is investigated at 800 °C with no-hold time (no-HT) and hold time (HT) to study creep–fatigue interactions. The tensile test results showed substantial differences between the strength and ductility properties of the base and weld materials at all 3 temperatures, however, the trends in temperature dependence of tensile properties are similar for both base and weld materials. LCF studies with no-HT and HT showed a strong influence of HT on the low cycle fatigue life of this alloy illustrating the substantial influence of creep mechanisms at 800 °C. Finally, cumulative values of creep versus fatigue damage fractions are plotted in a creep–fatigue interaction diagram and these results are discussed with respect to the existing bi

  19. Fatigue behavior of highly porous titanium produced by powder metallurgy with temporary space holders.

    Science.gov (United States)

    Özbilen, Sedat; Liebert, Daniela; Beck, Tilmann; Bram, Martin

    2016-03-01

    Porous titanium cylinders were produced with a constant amount of temporary space holder (70 vol.%). Different interstitial contents were achieved by varying the starting powders (HDH vs. gas atomized) and manufacturing method (cold compaction without organic binders vs. warm compaction of MIM feedstocks). Interstitial contents (O, C, and N) as a function of manufacturing were measured by chemical analysis. Samples contained 0.34-0.58 wt.% oxygen, which was found to have the greatest effect on mechanical properties. Quasi-static mechanical tests under compression at low strain rate were used for reference and to define parameters for cyclic compression tests. Not unexpectedly, increased oxygen content increased the yield strength of the porous titanium. Cyclic compression fatigue tests were conducted using sinusoidal loading in a servo-hydraulic testing machine. Increased oxygen content was concomitant with embrittlement of the titanium matrix, resulting in significant reduction of compression cycles before failure. For samples with 0.34 wt.% oxygen, R, σ(min) and σ(max) were varied systematically to estimate the fatigue limit (~4 million cycles). Microstructural changes induced by cyclic loading were then characterized by optical microscopy, SEM and EBSD.

  20. Experimental investigation and analysis of damage evolution in concrete under high-cyclic fatigue loadings; Experimentelle Untersuchung und Analyse der Schaedigungsevolution in Beton unter hochzyklischen Ermuedungsbeanspruchungen

    Energy Technology Data Exchange (ETDEWEB)

    Thiele, Marc

    2016-05-01

    The main objective of this thesis is the fatigue behavior of concrete under high-cycle compressive loadings. Current knowledge about fatigue behavior of concrete is still incomplete. This concerns especially the process of fatigue which is preceding the fatigue failure. The leak of knowledge about fatigue behavior is opposed to the steady growing importance of this topic within the practice in civil engineering. Therefore, within this thesis a systematic and comprehensive investigation of the process of fatigue itself was done. This contributes to the better understanding of the progression of damage and the corresponding processes within the material. The experimental investigation consisted mainly of experiments with constant amplitude loadings in compression with cylindrical specimen made of normal strength concrete. Two differed load levels were used which resulted in numbers of cycles to failure of 10{sup 6} and 10{sup 7} as well as 10{sup 3} and 10{sup 4}. The experiments were done in combination with different types of nondestructive and destructive testing methods like strain measuring, deformation of surface, ultrasonic signals, acoustic emissions, optical microscopy and also scattering electron microscopy. To access some parameters of influence in relation to the fatigue behavior additional creep tests and also several tests with different scales of specimen were done. The fatigue process of concrete is determined as an evolution of damage that starts from the beginning of the loading process. This evolution has manifold and different influences on the different material properties of concrete. In this relation a major finding was that fatigue related damage leads to a transformation of the complete stress-strain-relationship. This relationship is also subjected to an evolution process. Due to the authors observations it could not be determined that the investigated changes in macroscopic material behavior are caused by a development of micro cracks

  1. Nonpharmacologic approach to fatigue in patients with cancer.

    Science.gov (United States)

    Pachman, Deirdre R; Price, Katharine A; Carey, Elise C

    2014-01-01

    Cancer-related fatigue is a common yet underappreciated problem with a significant impact on functional ability and quality of life. Practice guidelines mandate that all cancer patients and survivors be screened for cancer-related fatigue (CRF) at regular intervals. Comorbidities that could contribute to fatigue should be treated, and patients with moderate to severe fatigue should undergo a comprehensive evaluation. Nonpharmacologic interventions are important tools to combat CRF and should be incorporated into routine practice. Physical activity, educational interventions, and cognitive-behavioral therapy have the most supportive data and can be recommended to patients with confidence. From a practical standpoint, general education on CRF is something that most care providers can readily offer patients as part of routine care. Other interventions that appear promising but are as yet lacking convincing evidence include mindfulness-based stress reduction, yoga, and acupuncture. Reiki, Qigong, hypnosis, and music therapy may be worthy of further investigation.

  2. Fatigue (PDQ)

    Science.gov (United States)

    ... of daily living . Better quality of life . More satisfaction with life. A greater sense of well-being. ... and decrease fatigue. The importance of eating enough food and drinking enough fluids. Physical therapy for patients ...

  3. Thermal Fatigue Testing of ZrO2-Y2O3 Thermal Barrier Coating Systems using a High Power CO2 Laser

    Science.gov (United States)

    Zhu, Dongming; Miller, Robert A.

    1997-01-01

    In the present study, the mechanisms of fatigue crack initiation and propagation, and of coating failure, under thermal loads that simulate diesel engine conditions, are investigated. The surface cracks initiate early and grow continuously under thermal Low Cycle Fatigue (LCF) and High Cycle Fatigue (HCF) stresses. It is found that, in the absence of interfacial oxidation, the failure associated with LCF is closely related to coating sintering and creep at high temperatures. Significant LCF and HCF interactions have been observed in the thermal fatigue tests. The fatigue crack growth rate in the ceramic coating strongly depends on the characteristic HCF cycle number, N*(sub NCF), which is defined as the number of HCF cycles per LCF cycle. The crack growth rate is increased from 0.36 microns/LCF cycle for a pure LCF test to 2.8 microns/LCF cycle for a combined LCF and HCF test at N*(sub NCF) about 20,000. A surface wedging model has been proposed to account for the HCF crack growth in the coating systems. This mechanism predicts that HCF damage effect increases with increasing surface temperature swing, the thermal expansion coefficient and the elastic modulus of the ceramic coating, as well as with the HCF interacting depth. A good agreement has been found between the analysis and experimental evidence.

  4. A Predictive Framework for Thermomechanical Fatigue Life of High Silicon Molybdenum Ductile Cast Iron Based on Considerations of Strain Energy Dissipation

    Science.gov (United States)

    Avery, Katherine R.

    Isothermal low cycle fatigue (LCF) and anisothermal thermomechanical fatigue (TMF) tests were conducted on a high silicon molybdenum (HiSiMo) cast iron for temperatures up to 1073K. LCF and out-of-phase (OP) TMF lives were significantly reduced when the temperature was near 673K due to an embrittlement phenomenon which decreases the ductility of HiSiMo at this temperature. In this case, intergranular fracture was predominant, and magnesium was observed at the fracture surface. When the thermal cycle did not include 673K, the failure mode was predominantly transgranular, and magnesium was not present on the fracture surface. The in-phase (IP) TMF lives were unaffected when the thermal cycle included 673K, and the predominant failure mode was found to be transgranular fracture, regardless of the temperature. No magnesium was present on the IP TMF fracture surfaces. Thus, the embrittlement phenomenon was found to contribute to fatigue damage only when the temperature was near 673K and a tensile stress was present. To account for the temperature- and stress-dependence of the embrittlement phenomenon on the TMF life of HiSiMo cast iron, an original model based on the cyclic inelastic energy dissipation is proposed which accounts for temperature-dependent differences in the rate of fatigue damage accumulation in tension and compression. The proposed model has few empirical parameters. Despite the simplicity of the model, the predicted fatigue life shows good agreement with more than 130 uniaxial low cycle and thermomechanical fatigue tests, cyclic creep tests, and tests conducted at slow strain rates and with hold times. The proposed model was implemented in a multiaxial formulation and applied to the fatigue life prediction of an exhaust manifold subjected to severe thermal cycles. The simulation results show good agreement with the failure locations and number of cycles to failure observed in a component-level experiment.

  5. Fatigue Strain and Damage Analysis of Concrete in Reinforced Concrete Beams under Constant Amplitude Fatigue Loading

    Directory of Open Access Journals (Sweden)

    Fangping Liu

    2016-01-01

    Full Text Available Concrete fatigue strain evolution plays a very important role in the evaluation of the material properties of concrete. To study fatigue strain and fatigue damage of concrete in reinforced concrete beams under constant amplitude bending fatigue loading, constant amplitude bending fatigue experiments with reinforced concrete beams with rectangular sections were first carried out in the laboratory. Then, by analyzing the shortcomings and limitations of existing fatigue strain evolution equations, the level-S nonlinear evolution model of fatigue strain was constructed, and the physical meaning of the parameters was discussed. Finally, the evolution of fatigue strain and fatigue damage of concrete in the compression zone of the experimental beam was analyzed based on the level-S nonlinear evolution model. The results show that, initially, fatigue strain grows rapidly. In the middle stages, fatigue strain is nearly a linear change. Because the experimental data for the third stage are relatively scarce, the evolution of the strain therefore degenerated into two phases. The model has strong adaptability and high accuracy and can reflect the evolution of fatigue strain. The fatigue damage evolution expression based on fatigue strain shows that fatigue strain and fatigue damage have similar variations, and, with the same load cycles, the greater the load level, the larger the damage, in line with the general rules of damage.

  6. Influence of Carbonation on Fatigue of Concrete with High Volume of Ground Granulated Blast-furnace Slag

    Institute of Scientific and Technical Information of China (English)

    YOU Lushen; JIANG Linhua; CHU Hongqiang

    2015-01-01

    The effect of carbonation on fatigue performance of ground granulated blast-furnace slag concrete was investigated. Based on the static compression tests of carbonated GGBS-concrete, the correlation between carbonation depth and compressive strength was analyzed and an equation between carbonation depth and compressive strength was put forward. Meanwhile, fatigue S-N curves of various carbonation depths were fitted, and the influence of carbonation on fatigue life and strength was studied. Carbonation has a dual effect on the fatigue behavior of GGBS-concrete. A fatigue equation based on the depth of carbonation was established. Also, the probabilistic distribution of fatigue life of carbonated concrete at a given stress level was modeled by the two-parameter Weibull distribution.

  7. Prevalence, Predictors, and Characteristics of Off-Treatment Fatigue in Breast Cancer Survivors

    NARCIS (Netherlands)

    Andrykowski, Michael A.; Donovan, Kristine A.; Laronga, Christine; Jacobsen, Paul B.

    2010-01-01

    BACKGROUND Lack of consensus regarding how to identify cancer patients with significant fatigue has hampered research regarding cancer-related fatigue (CRF) METHODS Specific criteria were used to identify CRF cases in women with stage 0-II breast cancer (BC group n = 304) Women completed assessments

  8. Inflammation and fatigue dimensions in advanced cancer patients and cancer survivors: An explorative study

    NARCIS (Netherlands)

    P.J. de Raaf (Pleun); S. Sleijfer (Stefan); C.H.J. Lamers (Cor); A. Jager (Agnes); J.W. Gratama (Jan-Willem); C.C.D. van der Rijt (Carin)

    2012-01-01

    textabstractBACKGROUND: Inflammation may underlie cancer-related fatigue; however, there are no studies that assess the relation between fatigue and cytokines in patients with advanced disease versus patients without disease activity. Furthermore, the relation between cytokines and the separate dime

  9. Sleep complaints and fatigue of airline pilots.

    Science.gov (United States)

    Reis, Cátia; Mestre, Catarina; Canhão, Helena; Gradwell, David; Paiva, Teresa

    2016-01-01

    This work aimed to determine daytime sleepiness and sleep complaints prevalence and the corresponding influence on perceived fatigue and to evaluate the influence of sociodemographic parameters and labour variables on sleep complaints, sleepiness and fatigue. A questionnaire was developed including socio-economic and labour issues and instruments, focused in sleep and fatigue. The response rate was 32% and the final sample had 435 pilots. The prevalence of sleep complaints was 34.9%, daytime sleepiness 59.3% and fatigue 90.6%. The high prevalence of sleep complaints, sleepiness and fatigue was disclosed in pilots, with those who fly short/medium having an added risk of fatigue.

  10. Fatigue in neuromuscular disorders: focus on Guillain–Barré syndrome and Pompe disease

    OpenAIRE

    2009-01-01

    textabstractFatigue accounts for an important part of the burden experienced by patients with neuromuscular disorders. Substantial high prevalence rates of fatigue are reported in a wide range of neuromuscular disorders, such as Guillain-Barré syndrome and Pompe disease. Fatigue can be subdivided into experienced fatigue and physiological fatigue. Physiological fatigue in turn can be of central or peripheral origin. Peripheral fatigue is an important contributor to fatigue in neuromuscular di...

  11. [Auditory fatigue].

    Science.gov (United States)

    Sanjuán Juaristi, Julio; Sanjuán Martínez-Conde, Mar

    2015-01-01

    Given the relevance of possible hearing losses due to sound overloads and the short list of references of objective procedures for their study, we provide a technique that gives precise data about the audiometric profile and recruitment factor. Our objectives were to determine peripheral fatigue, through the cochlear microphonic response to sound pressure overload stimuli, as well as to measure recovery time, establishing parameters for differentiation with regard to current psychoacoustic and clinical studies. We used specific instruments for the study of cochlear microphonic response, plus a function generator that provided us with stimuli of different intensities and harmonic components. In Wistar rats, we first measured the normal microphonic response and then the effect of auditory fatigue on it. Using a 60dB pure tone acoustic stimulation, we obtained a microphonic response at 20dB. We then caused fatigue with 100dB of the same frequency, reaching a loss of approximately 11dB after 15minutes; after that, the deterioration slowed and did not exceed 15dB. By means of complex random tone maskers or white noise, no fatigue was caused to the sensory receptors, not even at levels of 100dB and over an hour of overstimulation. No fatigue was observed in terms of sensory receptors. Deterioration of peripheral perception through intense overstimulation may be due to biochemical changes of desensitisation due to exhaustion. Auditory fatigue in subjective clinical trials presumably affects supracochlear sections. The auditory fatigue tests found are not in line with those obtained subjectively in clinical and psychoacoustic trials. Copyright © 2013 Elsevier España, S.L.U. y Sociedad Española de Otorrinolaringología y Patología Cérvico-Facial. All rights reserved.

  12. Chronic Fatigue Syndrome

    Science.gov (United States)

    Chronic fatigue syndrome (CFS) is a disorder that causes extreme fatigue. This fatigue is not the kind of tired feeling that ... activities. The main symptom of CFS is severe fatigue that lasts for 6 months or more. You ...

  13. Apparatus and method for fatigue testing of a material specimen in a high-pressure fluid environment

    Science.gov (United States)

    Wang, Jy-An; Feng, Zhili; Anovitz, Lawrence M; Liu, Kenneth C

    2013-06-04

    The invention provides fatigue testing of a material specimen while the specimen is disposed in a high pressure fluid environment. A specimen is placed between receivers in an end cap of a vessel and a piston that is moveable within the vessel. Pressurized fluid is provided to compression and tension chambers defined between the piston and the vessel. When the pressure in the compression chamber is greater than the pressure in the tension chamber, the specimen is subjected to a compression force. When the pressure in the tension chamber is greater than the pressure in the compression chamber, the specimen is subjected to a tension force. While the specimen is subjected to either force, it is also surrounded by the pressurized fluid in the tension chamber. In some examples, the specimen is surrounded by hydrogen.

  14. Mechanisms of deformation and fracture in high temperature low cycle fatigue of Rene 80 and IN 100

    Science.gov (United States)

    Romanoski, G. R., Jr.

    1982-01-01

    Specimens tested for the AGARD strain range partitioning program were investigated. Rene 80 and IN 100 were tested in air and in vacuum; at 871 C, 925 C, and 1000 C; and in the coated and uncoated condition. The specimens exhibited a multiplicity of high-temperature low-cycle fatigue damage. Observations of the various forms of damage were consistent with material and testing conditions and were generally in agreement with previous studies. In every case observations support a contention that failure occurs at a particular combination of crack length and maximum stress. A failure criterion which is applicable in the regime of testing studied is presented. The predictive capabilities of this criterion are straight forward.

  15. A Study on the Effects on Low Cycle Fatigue Life of a High Pressure Turbine Nozzle due to the Perturbation of Crystal Orientation of Grain of DS Materials

    Energy Technology Data Exchange (ETDEWEB)

    Huh, Jae Sung; Kang, Young Seok; Rhee, Dong Ho [Korea Aerospace Research Institute, Daejeon (Korea, Republic of)

    2016-07-15

    High pressure components of a gas turbine engine are generally made of nickel-base superalloys, using precision casting process due to complicated geometries with intricate channels and cooling holes. Turbine components manufactured from directionally solidified and single crystal materials have columnar grains; however, it is found that the crystals do not grow in its preferred direction, although the orientation can be controlled. This anisotropy can lead to the variations of elastic and Hill's parameters in constitutive equations, and they alter stress distributions and the low cycle fatigue life. We aims to evaluate the effects of perturbed crystal orientations on the structural integrity of a directionally solidified nozzle using low cycle fatigue life. We also attempt to show the necessity for the control of allowed manufacturing errors and stochastic analysis. Our approaches included conjugate heat transfer and structural analysis, along with low cycle fatigue life assessment.

  16. Experimental study of cyclic creep and high-cycle fatigue of welded joints of St3 steel by the DIC technique

    Energy Technology Data Exchange (ETDEWEB)

    Kibitkin, Vladimir V., E-mail: vvk@ispms.tsc.ru; Solodushkin, Andrey I., E-mail: s.ai@sibmail.com; Pleshanov, Vasily S., E-mail: vsp@ispms.tsc.ru [Institute of Strength Physics and Materials Science SB RAS, Tomsk, 634055 (Russian Federation)

    2015-10-27

    In the paper the mechanisms of plastic deformation and fracture of welded joints of steel St3 were investigated at high-cycle fatigue and cyclic creep by the digital image correlation (DIC) technique. The evolution of strain rate is studied for the following regions: base metal, HAZ, and fusion zone. This strain rate evolution can be considered as a mechanical response of material. Three stages of deformation evolution are shown: deformation hardening (I), fatigue crack initiation (II), and the last stage is related to main crack (III). Two criteria are offered to evaluate the current mechanical state of welded joints.

  17. Reductions in Anaemia and Fatigue are Associated with Improvements in Productivity in Cancer Patients Receiving Chemotherapy

    OpenAIRE

    2005-01-01

    Objective: Cancer-related anaemia is associated with fatigue that adversely affects patients' everyday functioning and wellbeing. We explore the impact of fatigue on patient productivity and caregiver burden. Methods: The analyses are based on data from a randomised, open-label, active-controlled, dose-finding trial of darbepoetin alfa among solid-tumour cancer patients with anaemia, who are receiving chemotherapy. Fatigue is assessed with the Functional Assessment of Cancer Therapy (FACT)-Fa...

  18. Investigations concerning cavitation and frost fatigue in clonal 84K poplar using high-resolution cavitron measurements.

    Science.gov (United States)

    Feng, Feng; Ding, Fei; Tyree, Melvin T

    2015-05-01

    Both drought and freezing-thawing of stems induce a loss of hydraulic conductivity (percentage loss of conductivity [PLC]) in woody plants. Drought-induced PLC is often accompanied by physical damage to pit membranes, causing a shift in vulnerability curves (cavitation fatigue). Hence, if cavitated stems are flushed to remove embolisms, the next vulnerability curve is different (shifted to lower tensions). The 84K poplar (Populus alba × Populus glandulosa) clone has small vessels that should be immune from frost-induced PLC, but results demonstrated that freezing-thawing in combination with tension synergistically increased PLC. Frost fatigue has already been defined, which is similar to cavitation fatigue but induced by freezing. Frost fatigue caused a transition from a single to a dual Weibull curve, but drought-fatigued stems had single Weibull curves shifted to lower tensions. Studying the combined impact of tension plus freezing on fatigue provided evidence that the mechanism of frost fatigue may be the extra water tension induced by freezing or thawing while spinning stems in a centrifuge rather than direct ice damage. A hypothesis is advanced that tension is enhanced as ice crystals grow or melt during the freeze or thaw event, respectively, causing a nearly identical fatigue event to that induced by drought. © 2015 American Society of Plant Biologists. All Rights Reserved.

  19. Investigations Concerning Cavitation and Frost Fatigue in Clonal 84K Poplar Using High-Resolution Cavitron Measurements1[OPEN

    Science.gov (United States)

    Feng, Feng; Ding, Fei; Tyree, Melvin T.

    2015-01-01

    Both drought and freezing-thawing of stems induce a loss of hydraulic conductivity (percentage loss of conductivity [PLC]) in woody plants. Drought-induced PLC is often accompanied by physical damage to pit membranes, causing a shift in vulnerability curves (cavitation fatigue). Hence, if cavitated stems are flushed to remove embolisms, the next vulnerability curve is different (shifted to lower tensions). The 84K poplar (Populus alba × Populus glandulosa) clone has small vessels that should be immune from frost-induced PLC, but results demonstrated that freezing-thawing in combination with tension synergistically increased PLC. Frost fatigue has already been defined, which is similar to cavitation fatigue but induced by freezing. Frost fatigue caused a transition from a single to a dual Weibull curve, but drought-fatigued stems had single Weibull curves shifted to lower tensions. Studying the combined impact of tension plus freezing on fatigue provided evidence that the mechanism of frost fatigue may be the extra water tension induced by freezing or thawing while spinning stems in a centrifuge rather than direct ice damage. A hypothesis is advanced that tension is enhanced as ice crystals grow or melt during the freeze or thaw event, respectively, causing a nearly identical fatigue event to that induced by drought. PMID:25786827

  20. Effect of composition and processing on the thermal fatigue and toughness of high performance die steels. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Wallace, J.F.; Wang, Y.; Schwam, D.

    1997-06-01

    The objective of this study was to improve average die life by optimizing die steel composition and the die processing. Four different steels, K,Q,C and Premium Grade H-13 have been investigated for thermal fatigue resistance and toughness. Optimum heat treatment processing has been determined for each steel with respect to austenitizing temperature and tempering conditions. The effect of the quenching rate on the thermal fatigue resistance and toughness of the die steels and the effect of Electro-Discharge Machining (EDM) on the thermal fatigue resistance were also determined. The immersion thermal fatigue specimen developed at CWRU was used to determine the thermal fatigue resistance as characterized by the two parameters of average maximum crack length and total crack area. The Charpy V-notch impact test was used over a -100{degrees}F to 450{degrees}F testing temperature range to evaluate the toughness and the brittle-ductile transition behavior. K steel has been identified as superior in performance compared to Premium Grade H-13. Q and C provide lower toughness and thermal fatigue resistance than H-13. Faster cooling rates provide higher thermal fatigue resistance and toughness. Higher austenitizing temperatures such as 1925{degrees}F compared to 1875{degrees}F provide better thermal fatigue resistance, but lower austenitizing temperatures of 1875{degrees}F provide better toughness. Higher hardness improves thermal fatigue resistance, but reduces toughness. A minimum of Rc 46 hardness is desired for aluminum die casting dies. EDM reduces the thermal fatigue resistance compared to conventional machining operations. When the EDM process of multiple small steps of decreasing energy and post-EDM treatments are employed, the effect can be reduced to a very slight amount. Preliminary evidence of the superior performance of the K steel has been provided by ongoing field testing of inserts in multiple cavity dies.

  1. Management of fatigue in patients with cancer -- a practical overview

    NARCIS (Netherlands)

    Koornstra, R.H.; Peters, M.; Donofrio, S.; Borne, B. van den; Jong, F.A. de

    2014-01-01

    Cancer-related fatigue (CRF) is a serious clinical problem and is one of the most common symptoms experienced by cancer patients. CRF has deleterious effects on many aspects of patient quality of life including their physical, psychological and social well-being. It can also limit their ability to f

  2. The occurrence of core muscle fatigue during high-intensity running exercise and its limitation to performance: the role of respiratory work.

    Science.gov (United States)

    Tong, Tomas K; Wu, Shing; Nie, Jinlei; Baker, Julien S; Lin, Hua

    2014-05-01

    This study investigated the occurrence of core muscle fatigue during high-intensity running exercise and its limitation to exercise performance. A secondary aim was to investigate whether respiratory muscle work performed during intense running periods, would contribute to core muscle fatigue. Nine male recreational runners were recruited for two reasons; (1) to perform a continuous treadmill run at 85% VO2max with and without core muscle fatigue in the CR_F and CR trials, respectively; and (2) to mimic the treadmill run-induced respiratory response recorded in the CR trial while subjects were free of whole-body exercise (Mimic trial). The changes in global core muscle function with fatigue in this study were evaluated by performing a sport-specific endurance plank test (SEPT), and the associated influence on running performance was examined by comparing the time to exhaustion during the treadmill run between the CR and CR_F trials. Subsequent to the treadmill run in the CR trial, SEPT (255.7 ± 85.3 vs 177.3 ± 80.6 s) was reduced from baseline in all runners. The reduction correlated (r = 0.67) with the concomitant decline in inspiratory muscle function revealed by maximal inspiratory mouth pressure (PImax: 151.3 ± 18.2 vs 133.3 ± 17.2 cmH2O, p core muscle workout in the CR_F trial, the running capacity was impaired significantly (10.7 ± 4.5 vs 6.5 ± 2.0 min, p core muscle fatigue in runners. The core muscle fatigue, which may be partly attributed to the corresponding respiratory work, may limit their running endurance. Inspiratory muscle function appears to be essential for core stabilization during the intense running. Key pointsA high-intensity maximum run may induce core muscle fatigue in runners. The core muscle fatigue, which may be partly attributed to the corresponding respiratory work, may limit their running endurance.In support of previous notion, inspiratory muscles may share the work of core stabilization during intense exercise, while

  3. Fatigue states after cancer treatment occur both in association with, and independent of, mood disorder: a longitudinal study

    Directory of Open Access Journals (Sweden)

    Davenport Tracey

    2006-10-01

    Full Text Available Abstract Background Persistent fatigue is recognised as one of the most common, ongoing symptoms reported by patients following cancer treatment and may have profound effects on the quality of life. However, recent cross-sectional studies also highlight the close relationship between cancer related fatigue (CRF and diagnoses of depression or anxiety disorder. There is currently limited information about the relationships between these conditions over time. We sought to examine the longitudinal relationships between fatigue and mood disorder in women treated with adjuvant therapy for early stage breast cancer. Methods Women who had recently completed adjuvant therapy for Stage I or II breast cancer (n = 212 were sent a questionnaire with established case thresholds for clinically-significant fatigue and psychological disorder, as well as a questionnaire assessing disability. Potentially relevant variables linked to fatigue states, including age, treatment modality, menopausal status, and hematological indices were recorded. The illness outcomes were assessed over 48 months of follow-up. Results The 176 women who responded to the questionnaire (84% had a mean age of 55 (range 24–83 years and had completed adjuvant treatment on average 10 (range 4.7 – 16.3 months previously. Radiotherapy had been administered, either alone (50% of women or in combination with chemotherapy (36%. Responses from 87 women (48% indicated a significant fatigue state (termed here post-cancer fatigue; PCF, and from 59 women (33% responses indicated significant psychological distress. Thirty-four women (19% were cases of fatigue alone (i.e. unaccompanied by psychological disorder, whereas 52 (30% were cases of both disorders. Multivariate analysis did not reveal any association between demographic, clinical or laboratory variables, and caseness for PCF. Self-reported functional disability was significantly associated with fatigue. Follow-up at 24, 36 and 48 months

  4. Seafarer fatigue

    DEFF Research Database (Denmark)

    Jepsen, Jørgen Riis; Zhao, Zhiwei; van Leeuwen, Wessel M. A.

    2015-01-01

    Background: The consequences of fatigue for the health and safety of seafarers has caused concern in the industry and among academics, and indicates the importance of further research into risk factors and preventive interventions at sea. This review gives an overview of the key issues relating...

  5. Expert consensus statement on diagnosis and treatment of cancer-related depressed mood state based on Chinese medicine

    Directory of Open Access Journals (Sweden)

    Shaodan Tian

    2015-10-01

    Full Text Available This consensus statement is organized into six parts: 1 Definitions: cancer-related depressed mood state is defined as a group of depressive symptoms, rather than major depressive disorder. Thus, “cancer-related depression” or “depressed mood state” is introduced as standard terminology and associated with the Chinese medicine concept of “yu zheng” (depression syndrome. 2 Pathogenesis: factors including psychological stress, cancer pain, cancer fatigue, sleep disorders, surgery trauma, chemotherapy, and radiation therapy are strongly associated with cancer-related depressed mood state. Crucial elements of pathogenesis are cancer caused by depression, depression caused by cancer, and the concurrence of phlegm, dampness, and stasis from constrained liver-qi and spleen deficiency. 3 Symptoms: these include core symptoms, psychological symptoms, and somatic symptoms. Depressed mood and loss of interest are the main criteria for diagnosis. 4 Clinical evaluation: based on the Mini-International Neuropsychiatric Interview and a numeric rating scale, and taking mood changes during cancer diagnosis and treatment into consideration, a questionnaire can be drafted to distinguish between major depressive disorder and cancer-related depression. The aim is to assist oncology clinicians to identify, treat, and refer patients with cancer-related depression. 5 Diagnosis: diagnosis should be based on the Chinese Classification for Mental Disorders (CCMD-3, taking patients' mood changes during diagnosis and treatment into consideration. 6 Treatment: treatments for cancer-related depression must be performed concurrently with cancer treatment. For mild depression, non-pharmacologic comprehensive therapies, including psychological intervention, music therapy, patient education, physical activity, and acupuncture, are recommended; for moderate depression, classical Chinese herbal formulas based on syndrome pattern differentiation combined with

  6. In-Situ Welding Carbon Nanotubes into a Porous Solid with Super-High Compressive Strength and Fatigue Resistance

    Science.gov (United States)

    Lin, Zhiqiang; Gui, Xuchun; Gan, Qiming; Chen, Wenjun; Cheng, Xiaoping; Liu, Ming; Zhu, Yuan; Yang, Yanbing; Cao, Anyuan; Tang, Zikang

    2015-06-01

    Carbon nanotube (CNT) and graphene-based sponges and aerogels have an isotropic porous structure and their mechanical strength and stability are relatively lower. Here, we present a junction-welding approach to fabricate porous CNT solids in which all CNTs are coated and welded in situ by an amorphous carbon layer, forming an integral three-dimensional scaffold with fixed joints. The resulting CNT solids are robust, yet still highly porous and compressible, with compressive strengths up to 72 MPa, flexural strengths up to 33 MPa, and fatigue resistance (recovery after 100,000 large-strain compression cycles at high frequency). Significant enhancement of mechanical properties is attributed to the welding-induced interconnection and reinforcement of structural units, and synergistic effects stemming from the core-shell microstructures consisting of a flexible CNT framework and a rigid amorphous carbon shell. Our results provide a simple and effective method to manufacture high-strength porous materials by nanoscale welding.

  7. [Cancer-related Cognitive Impairment: Current Knowledge and Future Challenges].

    Science.gov (United States)

    Tanimukai, Hitoshi

    2015-01-01

    Cancer patients often suffer from various distresses, including cognitive impairment. Cognitive impairment during and after cancer diagnosis and treatment are collectively called "Cancer-related cognitive impairment (CRCI)". The number of publications about cognitive impairment due to cancer therapy, especially chemotherapy, hormonal therapy, and radiotherapy, has been growing. Patients often worry not only about their disease condition and therapies, but also experience concerns regarding their memory, attention, and ability to concentrate. Even subtle CRCI can have a significant impact on social relationships, the ability to work, undergo treatment, accomplish meaningful goals, and the quality of life. Longitudinal studies of cancer patients indicated that up to 75% experience CRCI during treatment. Furthermore, CRCI may persist for many years following treatment. However, it is not well understood by most physicians and medical staff. CRCI can be mediated through increased inflammatory cytokines and hormonal changes. In addition, the biology of the cancer, stress, and attentional fatigue can also contribute to CRCI. Genetic factors and co-occurring symptoms may explain some of the inter-individual variability in CRCI. Researchers and patients are actively trying to identify effective interventional methods and useful coping strategies. Many patients are willing to discuss their disease condition and future treatment with medical staff and/or their families. Some patients also hope to discuss their end-of-life care. However, it is difficult to express their will after developing cognitive impairment. Advance care planning (ACP) can help in such situations. This process involves discussion between a patient, their family, and clinicians to clarify and reflect on values, treatment preferences, and goals to develop a shared understanding of how end-of-life care should proceed. The number of cancer patients with cognitive impairment has been increasing owing to the

  8. Influence of non-metallic second phases on fatigue behaviour of high strength steel components; Efecto de segundas fases no metalicas sobre el comportamiento a fatiga de componentes de acero con elevadas solicitaciones

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez, L.; Elvira, R.; Garcia de Andoin, A.; Pizarro, R.; Bertrand, C.

    2005-07-01

    To assess the real effect of the inclusion type on fatigue life of ultra clean high strength steels mechanical components made of 100Cr6 steel were fatigue tested and fracture surfaces analysed to determine the origin of fatigue cracks.Two heats proceedings from different steelmaking routes were taken for the tests. The material were forged into ring shape components which were fatigue tested under compression-compression loads. Failures were analysed by SFEM (Scanning field Emission Microscopy), proving that most of failures at high loads were originated by manganese sulphides of small size (10-70 micros), while less than 40% of all fatigue cracks due to inclusions were caused by titanium carbonitrides and hard oxides. It has been demonstrated that once number and size of hard inclusions have been reduced, the hazardous effect of oxides and carbonitrides on the fatigue life decreases also. However, softer inclusions as manganese sulphides, currently considered as less hazardous, play a more relevant role as direct cause of fatigue failure and they should be taken into account in a deeper way in order to balance both machinability and fatigue life requirements in high strength steel components. (Author) 11 refs.

  9. 核电汽轮机转子在低周疲劳与高周疲劳交互作用下裂纹扩展寿命的研究%Study on Crack Propagation Life under Low Cycle Fatigue and High Cycle Fatigue of Nuclear Steam Turbine Rotors

    Institute of Scientific and Technical Information of China (English)

    史进渊

    2015-01-01

    The calculation and assessment methods for the crack propagation life under low cycle fatigue and high cycle fatigue of nuclear steam turbine rotors is presented. The low high fatigue cycle stress amplitude and stress range as well as the crack propagation life calculation methods for low cycle fatigue and high cycle fatigue of nuclear steam turbine rotors are introduced. The calculation and assessment methods for the crack propagation calendar life under low cycle fatigue and high cycle fatigue of nuclear steam turbine rotors are given together with an application example for calculation and improvement of the fatigue crack propagation calendar life of a low pressure welded rotor for 1 000 MW nuclear steam turbines. The example results indicate that effect of the high cycle fatigue on the fatigue crack propagation calendar life of nuclear steam turbine rotors is bigger, it is necessary that assessment for the crack propagation life under low cycle fatigue and high cycle fatigue of rotors in the rotor structure design of new development for nuclear steam turbine and the rotor safety assessment for operation steam turbine for nuclear power plants.%提出核电汽轮机转子在低周疲劳与高周疲劳交互作用下裂纹扩展寿命的计算与评定方法.介绍核电汽轮机转子的低周疲劳与高周疲劳的应力幅与应力范围、低周疲劳裂纹扩展寿命与高周疲劳扩展寿命的计算方法.给出了核电汽轮机转子在低周疲劳与高周疲劳交互作用下裂纹扩展日历寿命的计算与评定方法,以及1 000 MW级核电汽轮机焊接低压转子疲劳裂纹扩展日历寿命的计算与改进的应用实例.结果表明,高周疲劳对汽轮机转子疲劳裂纹扩展日历寿命有比较大的影响,新研制核电汽轮机的转子结构设计和在役核电汽轮机的转子安全性评定,需要评估转子在低周疲劳与高周疲劳交互作用下裂纹扩展寿命.

  10. Fatigue in Patients with Autoimmune Thyroid Diseases

    Directory of Open Access Journals (Sweden)

    Jovanovic Zorica

    2017-03-01

    Full Text Available Fatigue is a common feature in a wide variety of chronic inflammatory and autoimmune diseases, but fatigue in autoimmune thyroid disease (AITD has not been investigated so far. The aim of this study was to examine fatigue in patients with AITD and to analyse the correlation between fatigue and the serum concentrations of thyroid antibodies, thyroid function and depression. This cross-sectional clinical study included 62 patients with increased concentrations of thyroperoxidase antibodies (TPOAbs as confirmation of AITD and 52 healthy individuals who were negative for thyroid antibodies; all controls were euthyroid. Thyroid antibodies, free thyroxine and thyroid-stimulating hormone were measured in the sera of all subjects. The Fatigue Severity Scale was used to measure the severity of fatigue; the level of depression was measured by the Beck Depression Inventory. Eight (12.9% patients had evident fatigue, 7 (11.3% patients had fatigue limit values, and 47 (75.8% patients had no fatigue. The frequency of fatigue was highly significant and almost three times higher in the AITD patients compared to the control group, in which only 2 (3.8% patients had evident fatigue. The majority of patients with fatigue had normal thyroid function, and only one (1.6% patient had overt hypothyroidism. Seven (11.3% patients had both fatigue and depression, whereas one (1.6% patient had fatigue without depression. We did not find significant correlations between fatigue and the concentrations of thyroid antibodies, but we found statistically significant correlations between fatigue and depression in AITD patients.

  11. The Effect of the Production Process and Heat Processing Parameters on the Fatigue Strength of High-Grade Medium-Carbon Steel

    Directory of Open Access Journals (Sweden)

    T. Lipiński

    2012-04-01

    Full Text Available The experimental material consisted of semi-finished products of high-grade, medium-carbon constructional steel with: manganese, chromium, nickel, molybdenum and boron. The experimental material consisted of steel products obtained in three metallurgical processes: electric and desulfurized (E, electric and desulfurized with argon-refined (EA and oxygen converter with vacuum degassed of steel (KP. The production process involved two melting technologies: in a 140-ton basic arc furnace with desulphurisation and argon refining variants, and in a 100-ton oxygen converter. Billet samples were collected to analyze: relative volume of impurities, microstructure and fatigue tests. The samples were quenched and austenitized at a temperature of 880oC for 30 minutes. They were then cooled in water and tempered by holding the sections at a temperature of 200, 300, 400, 500 and 600oC for 120 minutes and air-cooled. Fatigue tests were performed with the use of a rotary bending machine at a frequency of 6000 cpm. The results were statistical processed and presented in graphic form. This paper discusses the results of microstructural analyses, the distribution of the relative volume of impurities in different size ranges, the fatigue strength characteristics of different production processes, the average number of sample- damaging cycles and the average values of the fatigue strength coefficient for various heat processing options.

  12. Three-dimensional fatigue crack growth behavior in an aluminum alloy investigated with in situ high-resolution synchrotron X-ray microtomography

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, H., E-mail: huizhang@sp-mac4.pse.tut.ac.jp [Department of Production Systems Engineering, Toyohashi University of Technology, 1-1, Hibarigaoka, Tempaku, Toyohashi, Aichi 441-8580 (Japan); Toda, H.; Qu, P.C.; Sakaguchi, Y.; Kobayashi, M. [Department of Production Systems Engineering, Toyohashi University of Technology, 1-1, Hibarigaoka, Tempaku, Toyohashi, Aichi 441-8580 (Japan); Uesugi, K.; Suzuki, Y. [Japan Synchrotron Radiation Research Institute, 1-1-1, Kouto, Mikazuki-cho, Sayo-gun, Hyogo 679-5198 (Japan)

    2009-06-15

    The fatigue crack propagation process in an Al-Mg-Si alloy was investigated using in situ high-resolution synchrotron radiation X-ray microtomography. Tomography datasets were obtained at periodic intervals throughout the 120,000 fatigue cycles. Three-dimensional rendering of the through-thickness crack shape indicates that in a number of regions the adjacent sides of two branched cracks tend to overlap with fatigue cycling and form a crack overlapping region. Measured crack growth rates in each tomographic slice show that crack growth retardation generally occurs in these crack overlapping regions. The through-thickness variation in crack tip opening displacement was also measured and was used to account for the observed crack propagation behavior. Crack morphologies were observed at different load levels in a fatigue cycle. The crack closure level varied for two selected regions comprising different overlapping cracks. The correlation of the crack growth rate with both crack opening and closure levels was discussed and interpreted.

  13. Corrosion Fatigue

    Science.gov (United States)

    1981-10-01

    the applied protection systems, (2) crevices for moisture entrapment, (3) galvanic couples when steel or titanium fasteners are used, and (4) fatigue...Activ Material Structure Exposed Normal Environment* Unexposed Atmosphere Aluminum alloys Steel 1.25 2.0 4.0 Titanium " Magnesium " (4.0) (8.0) (10.0...APPRNDIX - Chromic Acid Anodizing The surface treatment consists in the following process : D egreasing with trichlorethylene vapor, * Pickling , Composition

  14. Increment of fatigue, depression, and stage fright during the first year of high-level education in music students.

    Science.gov (United States)

    Hildebrandt, Horst; Nübling, Matthias; Candia, Victor

    2012-03-01

    Public opinion associates music performance with pleasure, relaxation, and entertainment. Nevertheless, several studies have shown that professional musicians and music students are often affected by work-related burdens. These are closely related to stress and anxiety. Scrutinizing specific health strains and work attitudes of music students during their freshman year of high-level education. One hundred five students in three Swiss music universities were part of a longitudinal study using standardized assessment questionnaires. Before and after their first study year, some custom-made questionnaires designed to fit the particular work environment of musicians were used together with the already validated inquiry instruments. Fatigue, depression, and stage fright increased significantly. Our results indicate more study is needed and attempts should be made to minimize the stress level, improve the students' ability to cope with stress, and otherwise reduce their risk for injury. This appears particularly important considering the long-term negative effects of stressors on individuals' health as revealed by modern research.

  15. High-cycle fatigue of 10M Ni-Mn-Ga magnetic shape memory alloy in reversed mechanical loading

    Science.gov (United States)

    Aaltio, I.; Soroka, A.; Ge, Y.; Söderberg, O.; Hannula, S.-P.

    2010-07-01

    Application of Ni-Mn-Ga magnetic shape memory alloys in magnetic-field-induced actuation relies on their performance in long-term high-cycle fatigue. In this paper the performance and changes in the microstructure of a Ni-Mn-Ga 10M martensite single crystal material are reported in a long-term mechanically induced shape change cycling. The longest test was run for 2 × 109 cycles at a frequency of 250 Hz and a strain amplitude of ± 1%. After the test a clear increase of the dynamic stiffness of the material was detected. Three specimens out of ten were cycled until fracture occurred and their fracture mechanism was studied. It was observed that the macroscopic crack growth took place roughly at a 45° angle with respect to the loading direction that was along the lang100rang crystallographic direction of the sample. The macroscopic fracture plane seemed to correspond roughly to the {111} crystal planes. On a microscopic scale the fracture propagated in a step-like manner at least partly along crystallographic planes. The steps at the fracture plane correspond to the {101} twin planes, with the height of steps along the lang101rang direction. The final fracture of the samples occurred in a brittle manner after the critical stress was exceeded.

  16. Fatigue management in the workplace

    Directory of Open Access Journals (Sweden)

    Khosro Sadeghniiat-Haghighi

    2015-01-01

    Full Text Available Workers′ fatigue is a significant problem in modern industry, largely because of high demand jobs, long duty periods, disruption of circadian rhythms, and accumulative sleep debt that are common in many industries. Fatigue is the end result of integration of multiple factors such as time awake, time of day, and workload. Then, the full understanding of circadian biologic clock, dynamics of transient and cumulative sleep loss, and recovery is required for effective management of workplace fatigue. It can be more investigated in a new field of sleep medicine called occupational sleep medicine. Occupational sleep medicine is concerned with maintaining best productivity and safety in the industrial settings. The fatigue risk management system (FRMS is a comprehensive approach that is based on applying scientific evidence of sleep knowledge to manage workers fatigue. It is developing rapidly in the highly safety demand jobs; especially truck drivers, pilots, and power plant workers. The objective of this review is to explain about fatigue in the workplace with emphasis on its association work performance and errors/accidents. Also, we discussed about different methods of fatigue measurement and management.

  17. High strain FBG sensors for structural fatigue testing of military aircraft

    Science.gov (United States)

    Tejedor, S.; Kopczyk, J.; Nuyens, T.; Davis, C.

    2012-02-01

    This paper reports on a series of tests investigating the performance of Draw Tower Gratings (DTGs) combined with custom-designed broad area packaging and bonding techniques for high-strain sensing applications on Defence platforms. The sensors and packaging were subjected to a series of high-strain static and cyclic loading tests and a summary of these results is presented.

  18. 焊缝余高对焊接接头疲劳强度的影响%INFLUENCE OF PILE HIGH ON FATIGUE STRENGTH OF WELDING JOINT

    Institute of Scientific and Technical Information of China (English)

    吕晓春; 张志毅; 李爱民

    2011-01-01

    The influence of pile high on fatigue strength of AQ400NH material weldment were studied by testing fatigue property of AQ400NH material and its smooth and pile high weldment, observing fracture, determining S -N curve, calculating stress with ANSYS. The results show that the weld defect is the main reason to influence fatigue strength of smooth weldment than the pile high is the main reason to influence fatigue strength of weldment with pile high. To measure true strain and ANSYS calculation give the same result that stress concentrate area is in weld toe, there is an linear relation between the strength of stress concentrate and pile high.%通过测定AQ400NH材料的光滑焊件、余高焊件的疲劳性能、观察断口形貌、绘制S-N曲线以及用AN-SYS有限元程序计算应力分布,研究余高对焊接接头疲劳强度的影响.结果发现,对于光滑焊件,焊接缺陷是影响疲劳强度的主要原因,对于有余高焊件,余高的高度是影响疲劳强度的主要原因,实际应变测量和有限元计算都表明,焊趾部位是应力集中区,应力集中的强度和余高间有线性关系.

  19. A High-Sensitivity Potential-Drop Technique for Fatigue Crack Growth Measurements,

    Science.gov (United States)

    1979-08-01

    inappropriate to assume that crack growth characteristics at the surface are representative of crack behaviour in the specimen mid-thickness. 2.2 Ultrasonic...techniques has been described by several authors [23-25], and offers the advantages of high noise rejection and low current consumption . However, as the...Colonel B.C. Joshi, Military, Naval and Air Adviser, High Commission of India, Red Hill, A.C.T. Director, Defence Research Centre, Kuala Lumpur, Malaysia

  20. 焊接接头多轴高周疲劳评估方法%Multiaxial high-cycle fatigue assessment method for welded joints

    Institute of Scientific and Technical Information of China (English)

    张晓阳; 刘金勇; 曲先强

    2014-01-01

    本文主要对焊接接头的多轴高周疲劳评估方法展开研究.针对某管板焊接接头,分别采用Von Mises等效应力法、Eurocode3规范方法、IIW规范方法以及修正Wöhler曲线方法( MWCM )计算其多轴高周疲劳损伤寿命,并与试验寿命进行比较.对四种方法预测寿命的标准差进行分析.结果显示,等效应力法能够准确预测比例加载下的多轴高周疲劳寿命,但并不适用于估算非比例加载下的多轴疲劳损伤寿命,且预测结果偏于危险.MWCM既能够适用于比例加载下的多轴高周疲劳损伤寿命预测,也适用于非比例加载下的多轴高周疲劳损伤寿命预测,且预测寿命的标准差较小.%The multiaxial high-cycle fatigue assessment method for welded joints was carried out .Von Mises equivalent stress method, Eurocode3 recommended method , IIW recommended method and Modified Wöhler Curve Method ( MWCM ) were used to evaluate multiaxial high-cycle fatigue life of tube-plate welded joints , and results were compared with experimental fatigue life.Then the standard errors of estimated fatigue life for the four methods were analyzed .Results show that equiva-lent stress method can only be used to calculate multiaxial high-cycle fatigue life under proportional added multiaxial loads, whereas MWCM performed well to evaluate multiaxial fatigue life for welded structures subject to both proportional and non-proportional added multiaxial loads , moreover has a small standard error .

  1. Outcomes in Critically Ill Patients with Cancer-Related Complications

    Science.gov (United States)

    Torres, Viviane B. L.; Vassalo, Juliana; Silva, Ulysses V. A.; Caruso, Pedro; Torelly, André P.; Silva, Eliezer; Teles, José M. M.; Knibel, Marcos; Rezende, Ederlon; Netto, José J. S.; Piras, Claudio; Azevedo, Luciano C. P.; Bozza, Fernando A.; Spector, Nelson; Salluh, Jorge I. F.; Soares, Marcio

    2016-01-01

    Introduction Cancer patients are at risk for severe complications related to the underlying malignancy or its treatment and, therefore, usually require admission to intensive care units (ICU). Here, we evaluated the clinical characteristics and outcomes in this subgroup of patients. Materials and Methods Secondary analysis of two prospective cohorts of cancer patients admitted to ICUs. We used multivariable logistic regression to identify variables associated with hospital mortality. Results Out of 2,028 patients, 456 (23%) had cancer-related complications. Compared to those without cancer-related complications, they more frequently had worse performance status (PS) (57% vs 36% with PS≥2), active malignancy (95% vs 58%), need for vasopressors (45% vs 34%), mechanical ventilation (70% vs 51%) and dialysis (12% vs 8%) (P<0.001 for all analyses). ICU (47% vs. 27%) and hospital (63% vs. 38%) mortality rates were also higher in patients with cancer-related complications (P<0.001). Chemo/radiation therapy-induced toxicity (6%), venous thromboembolism (5%), respiratory failure (4%), gastrointestinal involvement (3%) and vena cava syndrome (VCS) (2%) were the most frequent cancer-related complications. In multivariable analysis, the presence of cancer-related complications per se was not associated with mortality [odds ratio (OR) = 1.25 (95% confidence interval, 0.94–1.66), P = 0.131]. However, among the individual cancer-related complications, VCS [OR = 3.79 (1.11–12.92), P = 0.033], gastrointestinal involvement [OR = 3.05 (1.57–5.91), P = <0.001] and respiratory failure [OR = 1.96(1.04–3.71), P = 0.038] were independently associated with in-hospital mortality. Conclusions The prognostic impact of cancer-related complications was variable. Although some complications were associated with worse outcomes, the presence of an acute cancer-related complication per se should not guide decisions to admit a patient to ICU. PMID:27764143

  2. High-density EEG coherence analysis using functional units applied to mental fatigue

    NARCIS (Netherlands)

    Caat, Michael ten; Lorist, Monicque M.; Bezdan, Eniko; Roerdink, Jos B.T.M.; Maurits, Natasha M.

    2008-01-01

    Electroencephalography (EEG) coherence provides a quantitative measure of functional brain connectivity which is calculated between pairs of signals as a function of frequency. Without hypotheses, traditional coherence analysis would be cumbersome for high-density EEG which employs a large number of

  3. Fatigue experiments on very high strength steel base material and transverse butt welds

    NARCIS (Netherlands)

    Pijpers, R.J.M.; Kolstein, M.H.; Romeijn, A.; Bijlaard, F.S.K.

    2009-01-01

    Very High Strength Steels (VHSS) with nominal strengths up to 1100 MPa have been available on the market for many years. However, the use of these steels in the civil engineering industry is still uncommon, due to lack of design and fabrication knowledge and therefore limited inclusion in codes. Mor

  4. Fatigue experiments on very high strength steel base material and transverse butt welds

    NARCIS (Netherlands)

    Pijpers, R.J.M.; Kolstein, M.H.; Romeijn, A.; Bijlaard, F.S.K.

    2009-01-01

    Very High Strength Steels (VHSS) with nominal strengths up to 1100 MPa have been available on the market for many years. However, the use of these steels in the civil engineering industry is still uncommon, due to lack of design and fabrication knowledge and therefore limited inclusion in codes.

  5. High-density EEG coherence analysis using functional units applied to mental fatigue

    NARCIS (Netherlands)

    Caat, Michael ten; Lorist, Monicque M.; Bezdan, Eniko; Roerdink, Jos B.T.M.; Maurits, Natasha M.

    2008-01-01

    Electroencephalography (EEG) coherence provides a quantitative measure of functional brain connectivity which is calculated between pairs of signals as a function of frequency. Without hypotheses, traditional coherence analysis would be cumbersome for high-density EEG which employs a large number of

  6. MANAGING FATIGUE IN SPORTS

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    @@ Fatigue is a multifactorial process. Depletion of energy sources, including adenosine triphosphate (ATP), phosphocreatine (PCr), plus carbohydrates (CHO) like muscle glycogen and blood glucose can contribute to fatigue.

  7. Effects of a selective educational system on fatigue, sleep problems, daytime sleepiness, and depression among senior high school adolescents in Taiwan

    Directory of Open Access Journals (Sweden)

    Chen TY

    2015-03-01

    Full Text Available Tien-Yu Chen,1,2 Yu-Ching Chou,3 Nian-Sheng Tzeng,1,2,4 Hsin-An Chang,1,2,4 Shin-Chang Kuo,1,2,5 Pei-Yin Pan,1,2 Yi-Wei Yeh,1,2,5 Chin-Bin Yeh,1,2 Wei-Chung Mao1,2,6 1Department of Psychiatry, Tri-Service General Hospital, 2School of Medicine, National Defense Medical Center, 3School of Public Health, National Defense Medical Center, 4Student Counseling Center, National Defense Medical Center, 5Graduate Institute of Medical Sciences, National Defense Medical Center, 6Institute of Brain Science, National Yang-Ming University, Taipei, Taiwan, Republic of China Objective: The aim of the study reported here was to clarify the effects of academic pressure on fatigue, sleep problems, daytime sleepiness, and depression among senior high school adolescents in Taiwan. Methods: This cross-sectional study enrolled 757 senior high school adolescents who were classified into four groups: Grade 1 (n=261, Grade 2 (n=228, Grade 3T (n=199; Grade 3 students who had another college entrance test to take, and Grade 3S (n=69; Grade 3 students who had succeeded in their college application. Fatigue, sleep quality, daytime sleepiness, and depression were assessed using the Chinese version of the Multidimensional Fatigue Symptom Inventory – Short Form, Pittsburgh Sleep Quality Index-Taiwan Form, the Chinese version of the Epworth Sleepiness Scale, and the Chinese version of the Beck Depression Inventory®-II (BDI-II, respectively. Results: Physical, emotional, and mental fatigue scores were all higher in higher-grade groups. The Grade 3T (test students had the worst fatigue severity, and the Grade 3S (success students had the least fatigue severity. More than half of the students (60.9% went to bed after 12 am, and they had on average 6.0 hours of sleep per night. More than 30% of the students in Grade 2 (37.3% and Grades 3T/S (30.2%/30.4% possibly had daily sleepiness problems. The students in Grade 3T had the worst BDI-II score (13.27±9.24, and the Grade 3S

  8. Fatigue behaviour of welded joints treated by high frequency hammer peening: Part 1 , experimental study

    OpenAIRE

    LE QUILLIEC, Guenhael; LIEURADE, Henri Paul; BOUSSEAU, Marc; DRISSI-HABTI, Monssef; INGLEBERT, Geneviève; MACQUET, Pascal; JUBIN, Laurent

    2011-01-01

    High frequency hammer peening is a recent improvement method which is probably one of the most effective for treating welded assemblies. A number of experimental results relating to this process are presented in this article. These results lead to better understand the mechanisms of the process, to outline the influence of the operating parameters and to confirm the role played by the initial quality of the welds. In the long run, the aim of this study is to propose an industrially applicable...

  9. Mechanics and modelling of high frequency mechanical impact and its effect on fatigue

    OpenAIRE

    LE QUILLIEC, Guenhael; LIEURADE, Henri Paul; DRISSI-HABTI, Monssef; INGLEBERT, Geneviève; MACQUET, Pascal; JUBIN, Laurent; BOUSSEAU, Marc

    2013-01-01

    High frequency mechanical impact is a recent improvement method which is probably one of the most effective for treating welded assemblies. A number of experimental results relating to this process are presented in this article. These results lead to better understand the mechanisms of the process, to outline the influence of the operating parameters and to confirm the role played by the initial quality of treated welds. In addition, a process is proposed in order to numerically estimate the ...

  10. Fatigue Behaviour of Welded Joints Treated by High Frequency Hammer Peening: Part I , Experimental Study

    OpenAIRE

    LE QUILLIEC, Guenhael; Lieurade, Henri-Paul; BOUSSEAU, Marc; DRISSI-HABTI, Monssef; INGLEBERT, Geneviève; MACQUET, Pascal; JUBIN, Laurent

    2011-01-01

    International audience; High frequency hammer peening is a recent improvement method which is probably one of the most effective for treating welded assemblies. A number of experimental results relating to this process are presented in this article. These results lead to better understand the mechanisms of the process, to outline the influence of the operating parameters and to confirm the role played by the initial quality of the welds. In the long run, the aim of this study is to propose an...

  11. Study of the quantitative assessment method for high-cycle thermal fatigue of a T-pipe under turbulent fluid mixing based on the coupled CFD-FEM method and the rainflow counting method

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Y.; Lu, T., E-mail: likesurge@sina.com

    2016-12-01

    Highlights: • Two characteristic parameters of the temperature fluctuations are used for qualitative analysis. • A quantitative assessment method for high-cycle thermal fatigue of a T-pipe is proposed. • The time-dependent curves for the temperature and thermal stress are not always “in-phase”. • Large magnitude of thermal stresses may not mean large number of fatigue cycles. • The normalized fatigue damage rate and normalized RMS temperature are positively related. - Abstract: With the development of nuclear power and nuclear power safety, high-cycle thermal fatigue of the pipe structures induced by the flow and heat transfer of the fluid in pipes have aroused more and more attentions. Turbulent mixing of hot and cold flows in a T-pipe is a well-recognized source of thermal fatigue in piping system, and thermal fatigue is a significant long-term degradation mechanism. It is not an easy work to evaluate thermal fatigue of a T-pipe under turbulent flow mixing because of the thermal loads acting at fluid–structure interface of the pipe are so complex and changeful. In this paper, a one-way Computational Fluid Dynamics-Finite Element Method (CFD-FEM method) coupling based on the ANSYS Workbench 15.0 software has been developed to calculate transient thermal stresses with the temperature fields of turbulent flow mixing, and thermal fatigue assessment has been carried out with this obtained fluctuating thermal stresses by programming in the software platform of Matlab based on the rainflow counting method. In the thermal analysis, the normalized mean temperatures and the normalized root mean square (RMS) temperatures are obtained and compared with the experiment of the test case from the Vattenfall benchmark facility to verify the accuracy of the CFD calculation and to determine the position which thermal fatigue is most likely to occur in the T-junction. Besides, more insights have been obtained in the coupled CFD-FEM analysis and the thermal fatigue

  12. Intravenous iron isomaltoside 1000 administered by high single-dose infusions or standard medical care for the treatment of fatigue in women after postpartum haemorrhage

    DEFF Research Database (Denmark)

    Holm, Charlotte; Thomsen, Lars Lykke; Norgaard, Astrid

    2015-01-01

    BACKGROUND: Postpartum haemorrhage can lead to iron deficiency with and without anaemia, the clinical consequences of which include physical fatigue. Although oral iron is the standard treatment, it is often associated with gastrointestinal side effects and poor compliance. To date, no published...... randomised controlled studies have compared the clinical efficacy and safety of standard medical care with intravenous administration of iron supplementation after postpartum haemorrhage.The primary objective of this study is to compare the efficacy of an intravenous high single-dose of iron isomaltoside...... 1000 with standard medical care on physical fatigue in women with postpartum haemorrhage. METHODS/DESIGN: In a single centre, open-labelled, randomised trial, women with postpartum haemorrhage exceeding 700 mL will be allocated to either a single dose of 1,200 mg of iron isomaltoside 1000 or standard...

  13. Microstructure characteristics and temperature-dependent high cycle fatigue behavior of advanced 9% Cr/CrMoV dissimilarly welded joint

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Qingjun [Shanghai Key Laboratory of Materials Laser Processing and Modification, Shanghai Jiao Tong University, Shanghai 200240 (China); Lu, Fenggui, E-mail: Lfg119@sjtu.edu.cn [Shanghai Key Laboratory of Materials Laser Processing and Modification, Shanghai Jiao Tong University, Shanghai 200240 (China); Shanghai Key Laboratory of Modern Metallurgy and Materials Processing, Shanghai University, Shanghai 200072 (China); Cui, Haichao [Shanghai Key Laboratory of Materials Laser Processing and Modification, Shanghai Jiao Tong University, Shanghai 200240 (China); Ding, Yuming; Liu, Xia [Shanghai Turbine Plant of Shanghai Electric Power Generation Equipment Co. Ltd., Shanghai 200240 (China); Gao, Yulai, E-mail: ylgao@shu.edu.cn [Shanghai Key Laboratory of Modern Metallurgy and Materials Processing, Shanghai University, Shanghai 200072 (China)

    2014-10-06

    Advanced 9% Cr and CrMoV steels chosen as candidate materials are first welded by narrow-gap submerged arc welding (NG-SAW) to fabricate the heavy section rotor. The present work focuses on studying the high-cycle fatigue (HCF) behavior of advanced 9% Cr/CrMoV dissimilarly welded joint at different temperatures. Conditional fatigue strength of this dissimilarly welded joint was obtained by HCF tests at room temperature (RT), 400 °C and 470 °C. It was observed that the failure occurred at the side of CrMoV base metal (BM), weld metal (WM) and heat affected zone (HAZ) of CrMoV side over 5×10{sup 7} cycles for the specimens tested at RT, 400 °C and 470 °C. The detailed microstructures of BMs, WMs and HAZs as well as fracture appearance were observed by optical microscopy (OM) and scanning electron microscopy (SEM). Precipitation and aggregation of carbides along the grain boundaries were clearly detected with the increase of temperature, which brought a negative effect on the fatigue properties. It is interesting to note that the inclusion size leading to crack initiation became smaller for the HCF test at higher temperature. Therefore, reduction in the inclusion size in a welded joint helps to improve the HCF performance at high temperature.

  14. Interpretation of the deep cracking phenomenon of tungsten monoblock targets observed in high-heat-flux fatigue tests at 20 MW/m{sup 2}

    Energy Technology Data Exchange (ETDEWEB)

    Li, Muyuan; You, Jeong-Ha, E-mail: you@ipp.mpg.de

    2015-12-15

    Highlights: • A theoretical interpretation is presented for deep crack of W monoblocks at 20 MW/m{sup 2}. • A consecutive process of crack initiation and growth was modeled in two stages. • The lifetime to crack initiation and the driving force of fracture are assessed. • Numerical predictions in this study agree well with the experimental findings. - Abstract: The HHF qualification tests conducted on the ITER divertor target prototypes showed that the tungsten monoblock armor suffered from deep cracking due to fatigue, when the applied high-heat-flux load approaches 20 MW/m{sup 2}. In spite of the critical implication of the deep cracking of armor on the structural integrity of a whole target component, no rigorous interpretation has been given to date. In this paper, a theoretical interpretation of the observed deep cracking feature is presented. A two-stage modeling approach is employed where deep cracking is thought to be a consecutive process of crack initiation and crack growth, which is assumed to be caused by plastic fatigue and brittle facture, respectively. The fatigue lifetime to crack initiation on the armor surface and the crack tip load of brittle fracture are assessed as a function of crack length and heat flux loads. The potential mechanisms of deep cracking are discussed for a typical slow transient high-heat-flux load cycle. It is shown that the quantitative predictions delivered in this study agree well with the observed findings offering insight into the nature of tungsten armor failure.

  15. Role of amino acids and vitamins in prevention of and rapid recovery from fatigue in the officers and soldiers at high altitude

    Directory of Open Access Journals (Sweden)

    Wen HUANG

    2012-01-01

    Full Text Available Objective  To explore the role of amino acids and vitamins in the prevention of and recovery from the fatigue related to military operation in the officers and soldiers at high altitude. Methods  The participants were 100 officers and soldiers, whose Modified Fatigue Rating Scale (MFIS scores were >21 points. The participants were randomly divided into three groups: capsule, placebo, and granules. Amino acids capsule (8 kinds of essential amino acids and 11 kinds of vitamins were contained, placebo, or amino acid-fructose beverage was given to respective group for 14 days continuously. The 3000-m running performance of the officers and soldiers stationed on a plateau was measured on the first and 14th days. The maximal grip strength of the right hand, fist-making times per minute, and the height reaching by the hand after three-step run-up for the same candidate were observed before and after fatigue loading (3000-m running. The blood levels of lactic acid and urea nitrogen of the candidates were measured after fatigue loading on the first and the 14th days. Results  The 3000-m running performance of officers and soldiers in the capsule and granules groups on the 14th day were better than that of the first day (PP>0.05. The difference between the capsule and the granules groups in grip strength, fist-making times per minute, and hand reaching height on the 14th day were obviously lower than that on the first day (PP>0.05. The blood levels of lactic acid and urea nitrogen in the capsule and granules groups on the 14th day were lower than that on the first day (PP>0.05. Conclusions  Amino acids and vitamins preparations can obviously improve the military performance capacity of officers and soldiers stationed on the plateau. Similarly, they can effectively prevent the lowering of jumping ability and grip strength caused by military fatigue. Therefore, amino acids and vitamins preparations play an important role in the prevention of and rapid

  16. Management of Total Pressure Recovery, Distortion and High Cycle Fatigue in Compact Air Vehicle Inlets

    Science.gov (United States)

    Anderson, Bernhard H.; Baust, Henry D.; Agrell, Johan

    2002-01-01

    It is the purpose of this study to demonstrate the viability and economy of Response Surface Methods (RSM) and Robustness Design Concepts (RDC) to arrive at micro-secondary flow control installation designs that maintain optimal inlet performance over a range of the mission variables. These statistical design concepts were used to investigate the robustness properties of 'low unit strength' micro-effector installations. 'Low unit strength' micro-effectors are micro-vanes set at very low angles-of-incidence with very long chord lengths. They were designed to influence the near wall inlet flow over an extended streamwise distance, and their advantage lies in low total pressure loss and high effectiveness in managing engine face distortion.

  17. Fatigue Crack Growth Behavior Evaluation of Grainex Mar-M 247 for NASA's High Temperature, High Speed Turbine Seal Test Rig

    Science.gov (United States)

    Delgado, Irebert R.; Steinetz, Bruce M.; Rimnac, Clare M.; Lewandowski, John J.

    2008-01-01

    The fatigue crack growth behavior of Grainex Mar-M 247 is evaluated for NASA s Turbine Seal Test Facility. The facility is used to test air-to-air seals primarily for use in advanced jet engine applications. Because of extreme seal test conditions of temperature, pressure, and surface speeds, surface cracks may develop over time in the disk bolt holes. An inspection interval is developed to preclude catastrophic disk failure by using experimental fatigue crack growth data. By combining current fatigue crack growth results with previous fatigue strain-life experimental work, an inspection interval is determined for the test disk. The fatigue crack growth life of the NASA disk bolt holes is found to be 367 cycles at a crack depth of 0.501 mm using a factor of 2 on life at maximum operating conditions. Combining this result with previous fatigue strain-life experimental work gives a total fatigue life of 1032 cycles at a crack depth of 0.501 mm. Eddy-current inspections are suggested starting at 665 cycles since eddy current detection thresholds are currently at 0.381 mm. Inspection intervals are recommended every 50 cycles when operated at maximum operating conditions.

  18. Mean stress effect under Multi-Axial High Cycle Fatigue loading for cast A356-T6 alloy

    Directory of Open Access Journals (Sweden)

    Houria M. Iben

    2014-06-01

    The obtained results show clearly that: (i the mean stress has detrimental, it is more significant in tension, lesser in tension-torsion case and slightly in torsion tests. (ii The improved DSG criterion describes very well the trend of the fatigue limit as a function of defect size and SDAS.

  19. Low-Cycle Fatigue Life and Fatigue Crack Propagation of Sintered Ag Nanoparticles

    Science.gov (United States)

    Shioda, Ryutaro; Kariya, Yoshiharu; Mizumura, Noritsuka; Sasaki, Koji

    2017-02-01

    The low-cycle fatigue life and fatigue crack propagation behavior of sintered silver nanoparticles were investigated using miniature specimens sintered at two different temperatures. The fatigue crack initiation life and fatigue crack propagation rate of sintered Ag nanoparticles were extremely sensitive to changes in the range of inelastic energy density and the cyclic J integral, exhibiting brittle characteristics, in contrast to tin-based lead-free solder alloys. With increasing sintering temperature, the fatigue crack propagation rate decreased. On the other hand, the effect of sintering temperature on the fatigue crack initiation life differed depending on the use of either a smooth specimen (low-cycle fatigue test) or notched specimen (fatigue crack propagation test). For the notched specimens, the probability of grain boundaries around the notch decreased due to increased sintering temperature. Therefore, the fatigue crack initiation life was increased with an increase in sintering temperature in the fatigue crack propagation test. In the smooth specimen, however, the fatigue life decreased with an increase in sintering temperature, as the elastic modulus of the specimen increased with increasing sintering temperature. In the low-cycle fatigue test, the specimen sintered with high internal stress started to develop crack initiation early, causing a decrease in the crack initiation life.

  20. Helicopter Fatigue Design Guide

    Science.gov (United States)

    1983-11-01

    de nouveaux materiaux ou technologies accentue I’importance que presente pour les forces de I’O.T.A.N. ce probleme de la maitrise des phenomenes de...fatigue interessant les helicopteres. La commission Structures et Materiaux de I’AGARD a ete conduite a proposer et developper une serie de reflexions...service life for the suspension components due to their vulnerabihty to darnage at high speeds. Spectrum No. 2 led to limitations being applied to

  1. Preferred and optimal stride frequency, stiffness and economy: changes with fatigue during a 1-h high-intensity run.

    Science.gov (United States)

    Hunter, Iain; Smith, Gerald A

    2007-08-01

    Metabolic cost of submaximal running at constant speed is influenced by various factors including fatigue and kinematic characteristics. Metabolic costs typically drift upwards during extended running while stride characteristics often shift away from initial. When non-fatigued, experienced runners naturally optimize stride frequency in a manner that minimizes oxygen uptake. An initial objective was to determine whether runners demonstrate a similar self-optimizing capability when fatigued where stride characteristics have perhaps shifted away from the initial state. A secondary objective involved measurement of vertical and leg stiffness characteristics as a potential explanation for frequency changes with fatigue. We hypothesized that runners decrease stride frequency and stiffness with fatigue while optimizing these characteristics to minimize metabolic cost. Sixteen experienced runners completed a near maximal effort 1-h treadmill run at a constant speed. Preferred and optimal stride frequencies (PSF and OSF) were measured near the beginning and end of the hour run using frequencies +/-4 and +/-8% around PSF. From vertical force data recorded throughout the run, leg and vertical stiffness were determined. As expected, oxygen uptake significantly increased during the run from 45.9 to 47.4 ml kg(-1) min(-1) (P = 0.004). There was no difference between preferred and optimal stride frequencies at the beginning or the end of running (P = 0.978), however both PSF and OSF significantly decreased from 1.45 to 1.43 Hz (P = 0.026). All runners self-optimized stride frequency at the beginning and end of one-hour of running despite changes of optimal stride frequency. Stiffness and stride frequency changes were subject specific with some runners exhibiting little to no change. No clear relationship of frequency or stiffness changes to economy was found.

  2. The significance of ultrafine film-like retained austenite in governing very high cycle fatigue behavior in an ultrahigh-strength MN–SI–Cr–C steel

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, P., E-mail: zhaoping12@mails.tsinghua.edu.cn [Key Laboratory of Advanced Materials of Ministry of Education, School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Zhang, B.; Cheng, C. [Materials Science and Engineering Research Center, Beijing Jiaotong University, Beijing 100044 (China); Misra, R.D K., E-mail: dmisra2@utep.edu [Laboratory for Excellence in Advanced Steel Research, Department of Metallurgical and Materials Engineering, University of Texas at El Paso, 500 W. University Avenue, El Paso, TX 79968-0520 (United States); Gao, G., E-mail: gaogh@bjtu.edu.cn [Materials Science and Engineering Research Center, Beijing Jiaotong University, Beijing 100044 (China); Bai, B.; Weng, Y. [Key Laboratory of Advanced Materials of Ministry of Education, School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Materials Science and Engineering Research Center, Beijing Jiaotong University, Beijing 100044 (China)

    2015-10-01

    We elucidate here the very high cycle fatigue (VHCF) behavior of an ultrahigh-strength medium carbon Mn–Si–Cr–C steel processed using the approach of bainite-based quenching and partitioning (BQ&P). The microstructure of BQ&P process comprised of bainite, carbon-depleted martensite, retained austenite (RA) and small amount of martensite/austenite island (M/A). The tensile strength (R{sub m}) and fatigue limit strength after 10{sup 9} cycles (σ{sub w9}) and in the non-failed condition were 1688 MPa and 875 MPa, respectively such that σ{sub w9}/R{sub m} exceeded conventional steels and was 0.52. Two types of failure modes were observed depending on the surface and microstructure, notably surface-induced failure and non-inclusion-induced failure, where the non-inclusion-induced failure was influenced by the microstructure. Inclusion-induced failure was absent. The study underscores that film-like retained austenite was the underlying reason for superior fatigue properties, hitherto not previously obtained.

  3. Markers for Routine Assessment of Fatigue and Recovery in Male and Female Team Sport Athletes during High-Intensity Interval Training

    Science.gov (United States)

    Wiewelhove, Thimo; Raeder, Christian; Meyer, Tim; Kellmann, Michael; Pfeiffer, Mark; Ferrauti, Alexander

    2015-01-01

    Aim Our study aimed to investigate changes of different markers for routine assessment of fatigue and recovery in response to high-intensity interval training (HIIT). Methods 22 well-trained male and female team sport athletes (age, 23.0 ± 2.7 years; V̇O2max, 57.6 ± 8.6 mL·min·kg−1) participated in a six-day running-based HIIT-microcycle with a total of eleven HIIT sessions. Repeated sprint ability (RSA; criterion measure of fatigue and recovery), countermovement jump (CMJ) height, jump efficiency in a multiple rebound jump test (MRJ), 20-m sprint performance, muscle contractile properties, serum concentrations of creatinkinase (CK), c-reactive protein (CRP) and urea as well as perceived muscle soreness (DOMS) were measured pre and post the training program as well as after 72 h of recovery. Results Following the microcycle significant changes (p HIIT induced fatigue and subsequent recovery. However, low accuracy of a single or combined use of these markers requires the verification of their applicability on an individual basis. PMID:26444557

  4. The challenge of integrating disparate high-content data: epidemiological, clinical and laboratory data collected during an in-hospital study of chronic fatigue syndrome.

    Science.gov (United States)

    Vernon, Suzanne D; Reeves, William C

    2006-04-01

    Chronic fatigue syndrome (CFS) is a debilitating illness characterized by multiple unexplained symptoms including fatigue, cognitive impairment and pain. People with CFS have no characteristic physical signs or diagnostic laboratory abnormalities, and the etiology and pathophysiology remain unknown. CFS represents a complex illness that includes alterations in homeostatic systems, involves multiple body systems and results from the combined action of many genes, environmental factors and risk-conferring behavior. In order to achieve understanding of complex illnesses, such as CFS, studies must collect relevant epidemiological, clinical and laboratory data and then integrate, analyze and interpret the information so as to obtain meaningful clinical and biological insight. This issue of Pharmacogenomics represents such an approach to CFS. Data was collected during a 2-day in-hospital study of persons with CFS, other medically and psychiatrically unexplained fatiguing illnesses and nonfatigued controls identified from the general population of Wichita, KS, USA. While in the hospital, the participants' psychiatric status, sleep characteristics and cognitive functioning was evaluated, and biological samples were collected to measure neuroendocrine status, autonomic nervous system function, systemic cytokines and peripheral blood gene expression. The data generated from these assessments was made available to a multidisciplinary group of 20 investigators from around the world who were challenged with revealing new insight and algorithms for integration of this complex, high-content data and, if possible, identifying molecular markers and elucidating pathophysiology of chronic fatigue. The group was divided into four teams with representation from the disciplines of medicine, mathematics, biology, engineering and computer science. The papers in this issue are the culmination of this 6-month challenge, and demonstrate that data integration and multidisciplinary

  5. Matrix metalloproteinase-2 (MMP-2) and its tissue inhibitor (TIMP-2) are prognostic factors in cervical cancer, related to invasive disease but not to high-risk human papillomavirus (HPV) or virus persistence after treatment of CIN.

    Science.gov (United States)

    Branca, M; Ciotti, M; Giorgi, C; Santini, D; Di Bonito, L; Costa, S; Benedetto, A; Bonifacio, D; Di Bonito, P; Paba, P; Accardi, L; Syrjänen, S; Favalli, C; Syrjänen, K

    2006-01-01

    Matrix metalloproteinase-2 (MMP-2) and its tissue inhibitor (TIMP-2) are important regulators of cancer invasion and metastasis. Their associations to high-risk (HR) human papillomavirus (HPV) in cervical intra-epithelial neoplasia (CIN) and cervical cancer (CC) are unexplored and their prognostic significance in CC remains controversial. As part of our HPV-PathogenISS study, a series of 150 CCs and 152 CIN lesions were examined using immunohistochemical (IHC) staining for MMP-2 and TIMP-2 and tested for HPV using PCR with 3 primer sets (MY09/11, GP5+/GP6+, SPF). Follow-up data were available from all squamous cell carcinoma patients and 67 CIN lesions had been monitored with serial PCR for HPV after cone treatment. MMP-2 increased with the grade of CIN, with major up-regulation upon transition to invasive cancer (OR 20.78) (95%CI 7.16-60.23) (p=0.0001). TIMP-2 retained its normal expression until CIN3, with dramatic down-regulation in invasive disease (p=0.0001 for trend). Thus, the MMP2:TIMP-2 ratio increased with progressive CIN, exceeding the value 1.0 only in invasive disease. Both MMP-2 and TIMP-2 are highly specific (TIMP-2; 100%) discriminators of CIN with 100% positive predictive value (TIMP-2), but suffer from low sensitivity and negative predictive value. Neither MMP-2 nor TIMP-2 showed any significant association with HR HPV or virus persistence/clearance. TIMP-2 (but not MMP-2) was a significant predictor of survival in univariate (Kaplan-Meier) analysis (p=0.007), but lost its significance in multivariate (Cox) analysis. The activities of MMP-2 and TIMP-2 in cervical carcinogenesis seem to be unrelated to HR-HPV The inverse MMP-2:TIMP-2 ratio is a sign of poor prognosis. A combination of a TIMP-2 assay with another test showing high SE and high NPV (e.g., HCII for HPV) should provide a potential screening tool capable of accurate detection of CIN.

  6. Fatigue life extension

    Science.gov (United States)

    Matejczyk, D. E.; Lin, J.

    1985-01-01

    Potential fatigue rejuvenation processes were carried out on fatigue-damaged material both with and without observable surface-connected fatigue cracks. The fatigue life of fatigue-damaged MAR-M246(Hf)(DS), a directionally solidified nickel-base superalloy used in turbine airfoils, was extended by reheat treatment. The fatigue life of fatigue-cracked Inconel 718, a wrought nickel-base superalloy used in a wide variety of advanced rocket engine components, was extended by electron-beam welding to close off the surface-connected crack, followed by hot isostatic pressing and reheat treatment.

  7. Microstructure influence on fatigue behaviour of austenitic stainless steels with high molybdenum content; Influencia de la microestructura en el comportamiento a fatiga de aceros inoxidables austeniticos con alto contenido en molibdeno

    Energy Technology Data Exchange (ETDEWEB)

    Onoro, J.; Gamboa, R.; Ranninger, C.

    2006-07-01

    Austenitic stainless steels with molybdenum present high mechanical properties and corrosion resistance to aggressive environments. These steels have been used to tank and vessel components for high liquids as phosphoric, nitric and sulphuric acids. These materials with low carbon and nitrogen addition have been proposed candidates as structural materials for the international thermonuclear experimental reactor (ITER) in-vessel components. Molybdenum addition in austenitic stainless steel improves mechanical and corrosion properties, but with it can produce the presence of nitrogen microstructure modifications by presence or precipitation of second phases. This paper summarises the fatigue and corrosion fatigue behaviour of two 317LN stainless steels with different microstructure. Fully austenitic steel microstructure show better fatigue, corrosion fatigue resistance and better ductility than austenitic steel with delta ferrite microstructure, mainly at low stresses. (Author)

  8. The use of methylphenidate to relieve fatigue.

    Science.gov (United States)

    Rojí, Rocío; Centeno, Carlos

    2017-09-06

    To review recent evidence on the efficacy and safety of methylphenidate as a symptomatic treatment of patients with cancer-related fatigue (CRF). Five clinical trials published since 2011 were identified. Two of these concluded that methylphenidate is more efficacious than placebo in providing relief from CRF, but the remaining three showed no difference in favour of methylphenidate. The studies were heterogeneous as per the dosage, scales used for evaluating fatigue and the target group studied. None of the studies detected serious reactions, and only mild and infrequent side-effects of methylphenidate were reported. Three new metanalyses show the slightly superior effect of methylphenidate compared to placebo in CRF. Overall, literature supports the existence of moderate benefit of methylphenidate in CRF, backed up by weak evidence. Future studies should aim at better identifying the profile of patients who would benefit most from this pharmacological intervention.

  9. Recent Progress in Cancer-Related Lymphedema Treatment and Prevention

    Science.gov (United States)

    Shaitelman, Simona F.; Cromwell, Kate D.; Rasmussen, John C.; Stout, Nicole L.; Armer, Jane M.; Lasinski, Bonnie B.; Cormier, Janice N.

    2016-01-01

    This article provides an overview of the recent developments in the diagnosis, treatment, and prevention of cancer-related lymphedema. Lymphedema incidence by tumor site is evaluated. Measurement techniques and trends in patient education and treatment are also summarized to include current trends in therapeutic and surgical treatment options as well as longer-term management. Finally, an overview of the policies related to insurance coverage and reimbursement will give the clinician an overview of important trends in the diagnosis, treatment, and management of cancer-related lymphedema. PMID:25410402

  10. Fatigue in cancer: A review of literature

    Directory of Open Access Journals (Sweden)

    Vijayakumar Narayanan

    2009-01-01

    Full Text Available Fatigue is a common symptom of advanced cancer limiting one′s activity and affecting the quality of life. It is a multidimensional symptom complex with subjective and objective components. Hence, its definition and assessment seems arbitrary, incomplete, and elusive. Components of fatigue often merge with other ′disease states′ as anemia, depression and so on, compounding difficulty to assess it separately. Fatigue has a high prevalence rate, and lasts longer in chronic diseases like cancer. Its association with treatment modalities like chemotherapy, radiotherapy alongside the primary disease process makes it seemingly ubiquitous in many cases. Systemic manifestation of cancer causes excess demand on body resources on cell repair, uncontrolled growth with metabolite accumulation causing fatigue. Co-morbid conditions of organic and psychological nature causes fatigue. There are many assessment tools for fatigue with different uses and objectives, simple and reproducible tools like Brief Fatigue Inventory, Edmonton Symptom assessment scale seem feasible in everyday practice. Management of fatigue is not straightforward and rewarding. Although treatment of cause appears to be an attractive option, it is not possible in all cases. Therapeutic agents targeting cytokine load is in early stages of study and available results are not favorable. Specific measures aimed at pain relief, prevention/treatment of sepsis, management of depression, avoidance of drugs causing fatigue, restoring the metabolic profile are important. Methyl phenidate, megestrol, and modafinil are some drugs with promising effect to treat fatigue, though confirmatory studies are yet to be established. Non-pharmacological methods are also helpful. Forewarning patients on upcoming fatigue, active regular exercise, and stress management are some of them. Fatigue being a multidimensional entity, single mode of therapy is insufficient. Combined modality tailored to individual

  11. Automotive stamped part fatigue design

    Directory of Open Access Journals (Sweden)

    Caudoux Mélanie

    2014-06-01

    Full Text Available Fatigue design of automotive axle parts is of prior concern because of these are high safety parts and they are expected to drive the overall vehicle mass reduction. In this framework, the stamping process is widely used to form axle parts, before assembling them by welding. Consequently, the mechanical and physical characteristics of the blank sheet are modified, having a strong influence on the fatigue behavior. In this paper, we address the consequences of the stamped process on the fatigue design and how they may be effectively taken into account in the automotive industry. Actually, the coupling between the stamping process and the fatigue design is under development at PSA Peugeot Citroën Company since several years. Such an analysis deals with some major topics: thickness variation, plastic hardening and deformation, and residual stress. All of these ingredients result in fatigue criteria evolutions: it is important to stress that the stamping process can have advantageous or disadvantageous consequences on the fatigue design. This is here highlighted on some examples, dealing with front and rear axles.

  12. Simulation Methods for High-Cycle Fatigue-Driven Delamination using Cohesive Zone Models - Fundamental Behavior and Benchmark Studies

    DEFF Research Database (Denmark)

    Bak, Brian Lau Verndal; Lindgaard, Esben; Turon, A.;

    2015-01-01

    A novel computational method for simulating fatigue-driven delamination cracks in composite laminated structures under cyclic loading based on a cohesive zone model [2] and new benchmark studies with four other comparable methods [3-6] are presented. The benchmark studies describe and compare...... the traction-separation response in the cohesive zone and the transition phase from quasistatic to fatigue loading for each method. Furthermore, the accuracy of the predicted crack growth rate is studied and compared for each method. It is shown that the method described in [2] is significantly more accurate...... than the other methods [3-6]. Finally, studies are presented of the dependency and sensitivity to the change in different quasi-static material parameters and model specific fitting parameters. It is shown that all the methods except [2] rely on different parameters which are not possible to determine...

  13. Effect of composition and processing on the thermal fatigue and toughness of high performance die steels. Year 1 report

    Energy Technology Data Exchange (ETDEWEB)

    Wallace, J.F.; Wang, Yumin; Schwam, D.

    1996-06-01

    The goal of this project is to extend the lifetime of dies for die casting by 20%. Since the die contributes about 10% to the cost of die cast parts, such an improvement in lifetime would result in annual savings of over $200 Million dollars. This is based on the estimated annual die production of one Billion dollars in the US. The major tasks of this two year project are: (1) Evaluate NEW DIE STEEL COMPOSITIONS that have been developed for demanding applications and compare them to Premium Grade H-13 die steel. (2) Optimize the AUSTENITIZING TREATMENT of the new composition. Assess the effects of fast, medium and slow COOLING RATES DURING HEAT TREATMENT, on the thermal fatigue resistance and toughness of the die steel. (3) Determine the effect of ELECTRO-DISCHARGE MACHINING (EDM) on the thermal fatigue resistance and impact properties of the steel. (4) Select demanding components and conduct IN-PLANT TESTING by using the new steel. Compare the performance of the new steel with identical components made of Premium Grade H-13. The immersion thermal fatigue specimen developed at CWRU is being used to determine resistance to heat checking, and the Charpy V-notch test for evaluating the toughness. The overall result of this project will be identification of the best steel available on the market and the best processing methods for aluminum die casting dies. This is an interim report for year 1 of the project.

  14. Effect of higher strain range cycling on near fatigue-limit fatigue life

    Energy Technology Data Exchange (ETDEWEB)

    Fukuoka, Chie; Nakagawa, Y.G. [Ishikawajima-Harima Heavy Industries Co. Ltd., Tokyo (Japan). Research Inst; Rosinski, S.T.

    1999-04-01

    The objective of this study is to clarify the effects of pre-cycling above the fatigue limit on near the fatigue-limit fatigue behaviors of SA508, low alloy steel for nuclear pressure vessels, correlating fatigue lifetime with microstructural changes in the bulk. It has been observed that dislocation cell structure is well developed in an as-received SA508 sample and the misorientation among cells increases with fatigue accumulation during fatigue tests. The cell to cell misorientation was measured and statistically quantified by the Selected Area electron beam Diffraction (SAD). It was shown that a fatigue crack started growing abruptly when the SAD value (the mean misorientation among cells) exceeded a critical angle, 4-5 degrees. Fatigue tests were performed for SA508 samples, first at a high total strain range (0.62%) to 10, 100, and 6000 cycles followed by cycling at near the fatigue-limit strain range (0.40%). The sample with pre-cycling for 100 and 6000 cycles failed while ones with pre-cycling for 10 cycles and without pre-cycling did not rupture till about 10{sup 6} cycles where the tests were terminated. Small surface cracks were found all samples pre-cycled at the high strain range but the cracks were arrested for a long time at the near fatigue limit cycling followed by an abrupt growth at the failure. It was found by the SAD that samples failed at the fatigue limit when the average misorientation among cells exceeds the critical angle regardless of pre-cycling histories. The SAD value changed even during cycling below the fatigue limit, and the change in SAD value was strongly influenced by the number of pre-cycling above the fatigue limit. These changes well agreed with fatigue lifetime of the samples. (author)

  15. Evolution of structural phase states of 08Cr18Ni10Ti steel subjected to high-cycle fatigue with electrostimulation

    Institute of Scientific and Technical Information of China (English)

    Molotova; K.Ye.; Konovalov; S.V.; Kozlov; E.V.; Ivanov; Yu.F.; Gromov; V.E.

    2005-01-01

    This work contains analysis results from the study of defective substructure and phase state of steel subjected to fatigue loading and pulse current action in order to increase its fatigue life.……

  16. Fatigue in Rheumatoid Arthritis.

    Science.gov (United States)

    Katz, Patricia

    2017-05-01

    The purpose of this study was to review the current information on fatigue in rheumatoid arthritis (RA). Severe fatigue is common among individuals with RA and has a significant impact on quality of life (QOL). RA-related factors (e.g., inflammation, pain) are associated with greater fatigue, but other factors, such as obesity, physical inactivity, sleep disturbance, and depression, explain the majority of variation in fatigue. Medications targeting RA have little effect on fatigue. Instead, the most effective interventions seem to address non-RA-specific factors such as physical inactivity or use cognitive behavioral approaches. No recommendations have been made for tools to measure fatigue in RA, leading to potential difficulty comparing studies. Although fatigue has great impact on patients' QOL, effective interventions that are feasible for broad dissemination remain elusive. Additional multi-faceted research is needed to identify modifiable sources of fatigue. Such research would be enhanced by harmonization of fatigue measurement across studies.

  17. Breast Cancer-Related Lymphedema: Implications for Family Leisure Participation

    Science.gov (United States)

    Radina, M. Elise

    2009-01-01

    An estimated 20% of breast cancer survivors face the chronic condition of breast cancer-related lymphedema. This study explored the ways in which women with this condition experienced changes in their participation in family leisure as one indicator of family functioning. Participants (N = 27) were interviewed regarding lifestyles before and after…

  18. Breast Cancer-Related Lymphedema: Implications for Family Leisure Participation

    Science.gov (United States)

    Radina, M. Elise

    2009-01-01

    An estimated 20% of breast cancer survivors face the chronic condition of breast cancer-related lymphedema. This study explored the ways in which women with this condition experienced changes in their participation in family leisure as one indicator of family functioning. Participants (N = 27) were interviewed regarding lifestyles before and after…

  19. Surgical inpatient cancer-related mortality in a Nigerian tertiary ...

    African Journals Online (AJOL)

    Surgical inpatient cancer-related mortality in a Nigerian tertiary hospital. ... One hundred and eight (63.2 %) were male. The yearly mortality ... The leading causes of mortality were cancer of prostate 50(29.2 %) and breast cancer 40(23.4 %).

  20. On the effect of deep-rolling and laser-peening on the stress-controlled low- and high-cycle fatigue behavior of Ti-6Al-4V at elevated temperatures up to 550?C

    Energy Technology Data Exchange (ETDEWEB)

    Ritchie, IAltenberger, RKNalla, YSano LWagner, RO

    2012-04-01

    The effect of surface treatment on the stress/life fatigue behavior of a titanium Ti-6Al-4V turbine fan blade alloy is investigated in the regime of 102 to 106 cycles to failure under fully reversed stress-controlled isothermal push-pull loading between 25? and 550?C at a frequency of 5 Hz. Specifically, the fatigue behavior was examined in specimens in the deep-rolled and laser-shock peened surface conditions, and compared to results on samples in the untreated (machined and stress annealed) condition. Although the fatigue resistance of the Ti-6Al-4V alloy declined with increasing test temperature regardless of surface condition, deep-rolling and laser-shock peening surface treatments were found to extend the fatigue lives by factors of more than 30 and 5-10, respectively, in the high-cycle and low-cycle fatigue regimes at temperatures as high as 550?C. At these temperatures, compressive residual stresses are essentially relaxed; however, it is the presence of near-surface work hardened layers, with a nanocystalline structure in the case of deep-rolling and dense dislocation tangles in the case of laser-shock peening, which remain fairly stable even after cycling at 450?-550?C, that provide the basis for the beneficial role of mechanical surface treatments on the fatigue strength of Ti-6Al-4V at elevated temperatures.

  1. Initiation and propagation life distributions of fatigue cracks and the life evaluation in high cycle fatigue of ADI; ADI zai no ko cycle hiro kiretsu hassei shinten jumyo bunpu tokusei to jumyo hyoka

    Energy Technology Data Exchange (ETDEWEB)

    Ochi, Y.; Ishii, A. [University of Electro Communications, Tokyo (Japan); Ogata, T. [Hitachi Metals, Ltd., Tokyo (Japan); Kubota, M. [Kyushu University, Fukuoka (Japan). Faculty of Engineering

    1997-10-15

    Rotating bending fatigue tests were carried out on austempered ductile cast iron (ADI) in order to investigate the statistical properties of life distributions of crack initiation and propagation, and also the evaluation of fatigue life. The results are summarized as follows: (1) The size of crack initiation sites of the material was represented by a Weibull distribution without regarding to the kinds of crack initiation sites such as microshrinkage and graphite grain. The crack initiation life scattered widely, but the scatter became much smaller as soon as the cracks grew. (2) The crack propagation life Nac which was defined as the minimum crack propagation rate showed lower scatter than the crack initation life. (3) The fatigue life of the material was evaluated well by Nac and the propagation rate after Nac. It was clear that the fatigue life of ductile cast iron was goverened by the scatter of Nac. 8 refs., 13 figs., 4 tabs.

  2. Review: Gigacycle fatigue data sheets for advanced engineering materials

    Directory of Open Access Journals (Sweden)

    Koji Yamaguchi, Takayuki Abe, Kazuo Kobayashi, Etsuo Takeuchi, Hisashi Hirukawa, Yoshio Maeda, Nobuo Nagashima, Masao Hayakawa, Yoshiyuki Furuya, Masuo Shimodaira and Kensuke Miyahara

    2007-01-01

    Full Text Available Gigacycle fatigue data sheets have been published since 1997 by the National Institute for Materials Science. They cover several areas such as high-cycle-number fatigue for high-strength steels and titanium alloys, the fatigue of welded joints, and high-temperature fatigue for advanced ferritic heat-resistant steels. Some unique testing machines are used to run the tests up to an extremely high number of cycles such as 1010 cycles. A characteristic of gigacycle fatigue failure is that it is initiated inside smooth specimens; the fatigue strength decreases with increasing cycle number and the fatigue limit disappears, although ordinary fatigue failure initiates from the surface of a smooth specimen and a fatigue limit appears. For welded joints, fatigue failure initiates from the notch root of the weld, because a large amount of stress is concentrated at the weld toe. The fatigue strength of welded joints has been obtained for up to 108 cycles, which is an extremely high number of cycles for large welded joints. The project of producing gigacycle fatigue data sheets is still continuing and will take a few more years to complete.

  3. 高镍铸铁排气歧管低周热疲劳研究%Low Cycle Thermal Fatigue of High Nickel Cast Iron Exhaust Manifold

    Institute of Scientific and Technical Information of China (English)

    袁守利; 王超; 刘志恩; 李雪妮

    2014-01-01

    针对某新开发的车用高镍铸铁排气歧管进行了低周热疲劳寿命预测研究,为获取准确的热边界条件,采用STAR-CCM+与有限元软件进行基于疲劳寿命试验条件的非稳态耦合传热分析,得到了排气歧管的对流换热系数和温度场,建立了具有真实装配关系并施加螺栓预紧力的排气歧管有限元模型,在对等效塑性应变分析的基础上,结合Coffin-Manson公式进行寿命预测。结果表明,在排气歧管开发过程中,采用该方法可以快速对其热疲劳寿命进行评估。%The low cycle thermal fatigue life of a newly developed high nickel cast iron exhaust manifold for vehicle was pre -dicted.In order to obtain a more accurate thermal boundary condition , STAR-CCM+and FE software were applied to analyze non-steady coupled heat transfer based on fatigue life experiment .The convective heat transfer coefficient and temperature field of exhaust manifold were then obtained .The FE model of the exhaust manifold was established with accurate assembly relation a-mong different components and bolt pre -tightening loads .At last, using Coffin-Manson equation , life prediction was completed based on analysis of equivalent plastic strain .The result indicates that the analysis method could speed up thermal fatigue life prediction of an exhaust manifold during developing process .

  4. Trajectories of fatigue in family caregivers of patients undergoing radiation therapy for prostate cancer.

    Science.gov (United States)

    Fletcher, Barbara A Swore; Schumacher, Karen L; Dodd, Marylin; Paul, Steven M; Cooper, Bruce A; Lee, Kathryn; West, Claudia; Aouizerat, Bradley E; Swift, Patrick S; Wara, William; Miaskowski, Christine

    2009-04-01

    Predictors of and trajectories for evening and morning fatigue were evaluated in family caregivers of oncology patients using hierarchical linear modeling. Evening fatigue trajectory fit a quadratic model. Predictors included baseline sleep disturbances in family caregivers and baseline evening fatigue in patients. Morning fatigue trajectory fit a linear model. Predictors were baseline trait anxiety, levels of perceived family support, and baseline morning fatigue in patients. Findings suggest considerable inter-individual variability in the trajectories of evening and morning fatigue. Evaluating family caregivers for sleep disturbance, anxiety, and poor family support, as well as high levels of patient fatigue, could identify those family caregivers at highest risk for sustained fatigue trajectories.

  5. Thermal Acoustic Fatigue Apparatus

    Data.gov (United States)

    Federal Laboratory Consortium — The Thermal Acoustic Fatigue Apparatus (TAFA) is a progressive wave tube test facility that is used to test structures for dynamic response and sonic fatigue due to...

  6. Insomnia and Fatigue

    Science.gov (United States)

    ... Styles Common Yoga Poses Special Situations Yoga and Lymphedema Risk Yoga and Metastatic Breast Cancer Side Effects ... Insomnia and Fatigue Treatment for Insomnia and Fatigue Lymphedema Lymphedema Risk Treating Lymphedema Menopausal Symptoms Mouth Sores ...

  7. A preliminary bending fatigue spectrum for steel monostrand cables

    DEFF Research Database (Denmark)

    Winkler, Jan; Fischer, Gregor; Georgakis, Christos T.;

    2011-01-01

    This paper presents the results of the experimental study on the bending fatigue resistance of high-strength steel monostrand cables. From the conducted fatigue tests in the high-stress, low-cycle region, a preliminary bending fatigue spectrum is derived for the estimation of monostrand cable...... service life expectancy. The presented preliminary bending fatigue spectrum of high-strength monostrands is currently unavailable in the published literature. The presented results provide relevant information on the bending mechanism and fatigue characteristics of monostrand steel cables in tension...

  8. Thermally activated processes of fatigue crack growth in steels

    Science.gov (United States)

    Tanaka, Masaki; Fujii, Atsushi; Noguchi, Hiroshi; Higashida, Kenji

    2014-02-01

    Fatigue crack growth rates in steels at high and low temperatures have been investigated using Paris curves. The fatigue crack growth rates at high temperatures are quite different from those at low temperatures. Arrhenius plots between fatigue crack growth rate (da/dN) and test temperatures at constant stress intensity factor range (ΔKI) indicate a difference of the rate-controlling process for fatigue crack growth with temperature. Slip deformation at the crack tip governs fatigue crack growth at high temperatures, while hydrogen diffusion is associated with crack growth at low temperatures.

  9. Markers for Routine Assessment of Fatigue and Recovery in Male and Female Team Sport Athletes during High-Intensity Interval Training.

    Directory of Open Access Journals (Sweden)

    Thimo Wiewelhove

    Full Text Available Our study aimed to investigate changes of different markers for routine assessment of fatigue and recovery in response to high-intensity interval training (HIIT.22 well-trained male and female team sport athletes (age, 23.0 ± 2.7 years; V̇O2 max, 57.6 ± 8.6 mL · min · kg(-1 participated in a six-day running-based HIIT-microcycle with a total of eleven HIIT sessions. Repeated sprint ability (RSA; criterion measure of fatigue and recovery, countermovement jump (CMJ height, jump efficiency in a multiple rebound jump test (MRJ, 20-m sprint performance, muscle contractile properties, serum concentrations of creatinkinase (CK, c-reactive protein (CRP and urea as well as perceived muscle soreness (DOMS were measured pre and post the training program as well as after 72 h of recovery.Following the microcycle significant changes (p < 0.05 in RSA as well as in CMJ and MRJ performance could be observed, showing a decline (%Δ ± 90% confidence limits, ES = effect size; RSA: -3.8 ± 1.0, ES = -1.51; CMJ: 8.4 ± 2.9, ES = -1.35; MRJ: 17.4 ± 4.5, ES = -1.60 and a return to baseline level (RSA: 2.8 ± 2.6, ES = 0.53; CMJ: 4.1 ± 2.9, ES = 0.68; MRJ: 6.5 ± 4.5, ES = 0.63 after 72 h of recovery. Athletes also demonstrated significant changes (p < 0.05 in muscle contractile properties, CK, and DOMS following the training program and after the recovery period. In contrast, CRP and urea remained unchanged throughout the study. Further analysis revealed that the accuracy of markers for assessment of fatigue and recovery in comparison to RSA derived from a contingency table was insufficient. Multiple regression analysis also showed no correlations between changes in RSA and any of the markers.Mean changes in measures of neuromuscular function, CK and DOMS are related to HIIT induced fatigue and subsequent recovery. However, low accuracy of a single or combined use of these markers requires the verification of their applicability on an individual basis.

  10. Optimal Fatigue Testing

    DEFF Research Database (Denmark)

    Faber, M. H.; Sørensen, John Dalsgaard; Kroon, I. B.

    1993-01-01

    This paper considers the reassessment of the reliability of tubular joints subjected to fatigue load. The reassessment is considered in two parts namely the task of utilizing new experimental data on fatigue life to update the reliability of the tubular joint ant the task of planning new fatigue ...

  11. Fatigue as it Affects Nursing.

    Science.gov (United States)

    2016-08-01

    : Editor's note: From its first issue in 1900 through to the present day, AJN has unparalleled archives detailing nurses' work and lives over more than a century. These articles not only chronicle nursing's growth as a profession within the context of the events of the day, but they also reveal prevailing societal attitudes about women, health care, and human rights. Today's nursing school curricula rarely include nursing's history, but it's a history worth knowing. To this end, From the AJN Archives highlights articles selected to fit today's topics and times.In this month's article from the January 1935 issue, Lillian M. Gilbreth, a highly respected psychologist and industrial engineer, examines the problem of fatigue in nursing. A nonnurse expert, Gilbreth notes the negative effects of fatigue on skills, a problem "enormously more serious when the product of the work is human comfort and sometimes even human life, as it often is with the work of the nurse." In their article in this issue, "Health Care Worker Fatigue," Lea Anne Gardner and Deborah Dubeck of the Pennsylvania Patient Safety Authority share examples of fatigue-related adverse events and discuss the need for both personal and institutional fatigue risk management strategies.

  12. Isothermal and nonisothermal fatigue behavior of a metal matrix composite

    Science.gov (United States)

    Gabb, T. P.; Gayda, J.; Mackay, R. A.

    1990-01-01

    The isothermal and nonisothermal fatigue resistance of a metal matrix composite (MMC) consisting of Ti-15V-3Cr-3Al-3Sn (Ti-15-3) matrix reinforced by 33 vol pct continuous SiC fibers was investigated. The fibers were nominally oriented parallel to the specimen axis. Isothermal fatigue tests were performed in air at 300 and 550 C. The MMC had good isothermal fatigue resistance at low cyclic stress, with fatigue cracks initiating from fiber-matrix interfaces and foil laminations. At high cyclic stresses, stress relaxation in the matrix reduced isothermal composite fatigue resistance at 550 C. Nonisothermal fatigue loading substantially degraded composite fatigue resistnce. This degradation was produced by a thermomechanical fatigue damage mechanism associated with the fiber-matrix interfaces.

  13. Driver fatigue through nightshifts in succession

    Energy Technology Data Exchange (ETDEWEB)

    Mabbott, N.; Lloyd, B. [ARRB Group Ltd., Leederville, WA (United States)

    2005-07-01

    Coal Services (Health and Safety Trust) funded ARRB Transport Research Ltd. to investigate fatigue and performance of truck drivers over consecutive shifts. The main questions were to assess: What is the most important contributor to acute fatigue in mining? Is it length of shift or is it time of day? What is the limit of successive day or night shifts before chronic fatigue affects operator performance in open cut mines? The project methodology included utilising ARRB Fatigue Monitoring Devices in eight haul trucks, testing 24 subjects over several weeks. Each subject filled in a Fatigue Risk Questionnaire on lifestyle and health. Operators worked a 14 night, 1 day off, 13 day roster of 12-hour shifts in a fly-in, fly-out operation with excellent opportunities for restorative sleep between shifts. A total of 3,500 hours of real-time data was collected, representing the first set of objective, real-time driver performance data for Australian mining. The major finding within this study is the combined influence of circadian rhythms and individual variability on performance. The lifestyle habits and the health of individuals have a profound effect on operator performance as shown by the strong positive correlation between high fatigue risk scores from the Fatigue Risk Questionnaire and poor performance. An individualistic approach would appear to have the best chance of reducing high potential incidents due to fatigue through successive nightshifts. 9 refs., 14 figs.

  14. Fatigue Characteristics of Selected Light Metal Alloys

    Directory of Open Access Journals (Sweden)

    Cieśla M.

    2016-03-01

    Full Text Available The paper addresses results of fatigue testing of light metal alloys used in the automotive as well as aerospace and aviation industries, among others. The material subject to testing comprised hot-worked rods made of the AZ31 alloy, the Ti-6Al-4V two-phase titanium alloy and the 2017A (T451 aluminium alloy. Both low- and high-cycle fatigue tests were conducted at room temperature on the cycle asymmetry ratio of R=-1. The low-cycle fatigue tests were performed using the MTS-810 machine on two levels of total strain, i.e.Δεc= 1.0% and 1.2%. The high-cycle fatigue tests, on the other hand, were performed using a machine from VEB Werkstoffprufmaschinen-Leipzig under conditions of rotary bending. Based on the results thus obtained, one could develop fatigue life characteristics of the materials examined (expressed as the number of cycles until failure of sample Nf as well as characteristics of cyclic material strain σa=f(N under the conditions of low-cycle fatigue testing. The Ti-6Al-4V titanium alloy was found to be characterised by the highest value of fatigue life Nf, both in lowand high-cycle tests. The lowest fatigue life, on the other hand, was established for the aluminium alloys examined. Under the high-cycle fatigue tests, the life of the 2017A aluminium and the AZ31 magnesium alloy studied was determined by the value of stress amplitude σa. With the stress exceeding 150 MPa, it was the aluminium alloy which displayed higher fatigue life, whereas the magnesium alloy proved better on lower stress.

  15. Role of nuclear factor κB-mediated inflammatory pathways in cancer-related symptoms and their regulation by nutritional agents.

    Science.gov (United States)

    Gupta, Subash C; Kim, Ji Hye; Kannappan, Ramaswamy; Reuter, Simone; Dougherty, Patrick M; Aggarwal, Bharat B

    2011-06-01

    Cancer is a disease characterized by dysregulation of multiple genes and is associated with symptoms such as cachexia, anorexia, fatigue, depression, neuropathic pain, anxiety, cognitive impairment, sleep disorders and delirium (acute confusion state) in medically ill patients. These symptoms are caused by either the cancer itself or the cancer treatment. During the past decade, increasing evidence has shown that the dysregulation of inflammatory pathways contributes to the expression of these symptoms. Cancer patients have been found to have higher levels of proinflammatory cytokines such as interleukin-6. The nuclear factor (NF)-κB is a major mediator of inflammatory pathways. Therefore, anti-inflammatory agents that can modulate the NF-κB activation and inflammatory pathways may have potential in improving cancer-related symptoms in patients. Because of their multitargeting properties, low cost, low toxicity and immediate availability, natural agents have gained considerable attention for prevention and treatment of cancer-related symptoms. How NF-κB and inflammatory pathways contribute to cancer-related symptoms is the focus of this review. We will also discuss how nutritional agents such as curcumin, genistein, resveratrol, epigallocatechin gallate and lycopene can modulate inflammatory pathways and thereby reduce cancer-related symptoms in patients.

  16. A Case of Femoral Arteriovenous Fistula Causing High-Output Cardiac Failure, Originally Misdiagnosed as Chronic Fatigue Syndrome

    Directory of Open Access Journals (Sweden)

    J. Porter

    2014-01-01

    Full Text Available Percutaneous arterial catheterisation is commonly undertaken for a range of diagnostic and interventional procedures. Iatrogenic femoral arteriovenous fistulas are an uncommon complication of these procedures. Most are asymptomatic and close spontaneously, but can rarely increase in size leading to the development of symptoms. We report a case of an iatrogenic femoral arteriovenous fistula, causing worsening congestive cardiac failure, in a 34-year-old marathon runner. This was originally diagnosed as chronic fatigue syndrome. Following clinical examination, duplex ultrasound, and CT angiography a significant arteriovenous fistula was confirmed. Elective open surgery was performed, leading to a dramatic and rapid improvement in symptoms. Femoral arteriovenous fistulas have the potential to cause significant haemodynamic effects and can present many years after the initial procedure. Conservative, endovascular, and open surgical management strategies are available.

  17. Crack nucleation using combined crystal plasticity modelling, high-resolution digital image correlation and high-resolution electron backscatter diffraction in a superalloy containing non-metallic inclusions under fatigue.

    Science.gov (United States)

    Zhang, Tiantian; Jiang, Jun; Britton, Ben; Shollock, Barbara; Dunne, Fionn

    2016-05-01

    A crystal plasticity finite-element model, which explicitly and directly represents the complex microstructures of a non-metallic agglomerate inclusion within polycrystal nickel alloy, has been developed to study the mechanistic basis of fatigue crack nucleation. The methodology is to use the crystal plasticity model in conjunction with direct measurement at the microscale using high (angular) resolution-electron backscatter diffraction (HR-EBSD) and high (spatial) resolution-digital image correlation (HR-DIC) strain measurement techniques. Experimentally, this sample has been subjected to heat treatment leading to the establishment of residual (elastic) strains local to the agglomerate and subsequently loaded under conditions of low cyclic fatigue. The full thermal and mechanical loading history was reproduced within the model. HR-EBSD and HR-DIC elastic and total strain measurements demonstrate qualitative and quantitative agreement with crystal plasticity results. Crack nucleation by interfacial decohesion at the nickel matrix/agglomerate inclusion boundaries is observed experimentally, and systematic modelling studies enable the mechanistic basis of the nucleation to be established. A number of fatigue crack nucleation indicators are also assessed against the experimental results. Decohesion was found to be driven by interface tensile normal stress alone, and the interfacial strength was determined to be in the range of 1270-1480 MPa.

  18. ''Risk safety of high frequency fatigue rupture for the vapor generators tubes''; ''Prevention du risque de rupture par fatigue vibratoire des tubes de generateurs de vapeur''

    Energy Technology Data Exchange (ETDEWEB)

    Solgadi, E.; Le Duff, J.A. [FRAMATOME, 92 - Paris-La-Defense (France); Bussy, B. [Electricite de France, 75 - Paris (France). Service Etudes et Projets Thermiques et Nucleaires

    2001-07-01

    Among the different rupture ways identified since 1975 for the steam generators tubes, the fatigue damage occurred on four cases. Two of them are analyzed in this paper: the NORTH ANNA 1 and the MIHAMA 2. From these analysis, it appears that the fatigue crack happens with aggravating factors as the tube embedding, the anti-vibration bars or fretting corrosion. As a preventive, the number of anti-vibration bars has been increase for the vapor generators 1300 and a new system of damper has been developed and implemented on the vapor generator 900. (A.L.B.)

  19. Study on the Ultra High Cycle Bending Vibration Fatigue Test of Titanium Alloys%钛合金超高周弯曲振动疲劳性能试验

    Institute of Scientific and Technical Information of China (English)

    申景生; 李全通; 吴晓峰; 高潮; 刘青川

    2011-01-01

    Based on the three-point bending method, an ultra high cycle bending vibration fatigue system is developed and the design method of fatigue test specimens is introduced too. The S - N curve of titanium alloy TC17 is determined by the ultra high cycle dissymmetrical bending fatigue system (20 kHz). The result shows that when stress ratio(R) is -1, the S - N curve of titanium alloy TC17 is a continuously declining curve, The specimens continue to fail over 107 stress cycles. In 107 weeks time, the samples don' t happen the fatigue damage, so it does not exist in the traditional sense fatigue limit.%在三点弯曲超高周疲劳试验的基础上,开发了悬臂梁式弯曲振动超高周疲劳试验系统,并介绍了疲劳试验试片的设计方法.利用超高周弯曲疲劳试验系统(20 kHz)测定了钛合金TC17的S-N曲线,结果表明,当应力比R=-1时TC17钛合金的S-N曲线是一条连续下降型曲线,在107周次以后,试样仍未发生疲劳破坏,不存在传统意义上的疲劳极限.

  20. Reliability Evaluation of Aluminum Alloy under High Temperature Based on Low Cycle Fatigue Crack Growth%铝合金高温低周疲劳裂纹扩展可靠性评估

    Institute of Scientific and Technical Information of China (English)

    李旭东; 张连峰; 朱武峰; 丁文勇

    2013-01-01

    Fatigue crack growth rate of AA 6151-T6 in high temperature was tested. The fatigue crack growth rate formula was obtained based on reliability theory. The result showed that fatigue crack growth of AA 6151-T6 exists threshold value in high temperature, which decreases with temperature increasing. The purpose was to provide reference for safe life prediction of AA 6151-T6 component.The present thesis made a research on the fatigue crack growth rate of AA 6151-T6 subjected to various elevated, and proposed a reliability based formula to evaluate FCG, which provided the basis of 6151-T6 aluminum alloy component safe life prediction. The method demonstrates the existence of fatigue crack growth threshold value of 6151-T6 aluminum alloy subjected to elevated temperature, which decreases with temperature increasing.%通过对不同温度下6151-T6合金的研究,获得了一种基于可靠性理论的裂纹扩展速率表达式,为预测6151-T6铝合金构件的安全寿命提供依据。该表达式表明,在高温条件下,6151-T6铝合金疲劳裂纹扩展存在门槛值,而且该门槛值会随着环境温度的升高而降低。

  1. Fatigue Damage in Wood

    DEFF Research Database (Denmark)

    Clorius, Christian Odin; Pedersen, Martin Bo Uhre; Hoffmeyer, Preben;

    1996-01-01

    An investigation of fatigue failure in wood subjected to load cycles in compression parallel to grain is presented. Fatigue failure is found to depend both on the total time under load and on the number of cycles.Recent accelerated fatigue research on wood is reviewed, and a discrepancy between...... failure explanation under fatigue and static load conditions is observed. In the present study small clear specimens of spruce are taken to failure in square wave formed fatigue loading at a stress excitation level corresponding to 80% of the short term strength. Four frequencies ranging from 0.01 Hz...... to 10 Hz are used. The number of cycles to failure is found to be a poor measure of the fatigue performance of wood. Creep, maximum strain, stiffness and work are monitored throughout the fatigue tests. Accumulated creep is suggested identified with damage and a correlation between stiffness reduction...

  2. 涡轮叶片高温多轴低周疲劳/蠕变寿命研究%Research on low cycle-multiaxial fatigue-creep life prediction at high temperature for turbine blade

    Institute of Scientific and Technical Information of China (English)

    彭立强; 王健

    2009-01-01

    SHANG Deguang multiaxial fatigue damage model was used to amend Man-son-Coffin equation of multiaxial fatigue prediction and SWT(Smith-Waston-Topper) formu-la, based on working condition of turbine rotor blade in aviation engine. A new method of fa-tigue life prediction of turbine blade was presented, which was adapted for non-proportional loading of turbine blade fatigue damage at high temperature. A case of turbine blade was cal-culated for fatigue life and the total damage of 1000 hours flying, in well agreement with the fact of blade fatigue damage. So the model of multiaxial fatigue prediction is rational and feasible.%针对航空发动机涡轮转子叶片工作环境,对Manson-Coffin多轴疲劳预测方程和SWT(Smith-Waston-Topper)公式进行修正,同时采用尚德广多轴疲劳损伤参量,给出涡轮叶片新的疲劳寿命预测方法,以适应涡轮叶片高温变幅非比例加载下疲劳损伤情况.通过算例计算了某涡轮叶片疲劳寿命及1000h的总损伤,与叶片实际疲劳破坏相吻合,验证该高温多轴疲劳损伤计算模型的合理性和可行性.

  3. On the Fatigue Analysis of Wind Turbines

    Energy Technology Data Exchange (ETDEWEB)

    Sutherland, Herbert J.

    1999-06-01

    Modern wind turbines are fatigue critical machines that are typically used to produce electrical power from the wind. Operational experiences with these large rotating machines indicated that their components (primarily blades and blade joints) were failing at unexpectedly high rates, which led the wind turbine community to develop fatigue analysis capabilities for wind turbines. Our ability to analyze the fatigue behavior of wind turbine components has matured to the point that the prediction of service lifetime is becoming an essential part of the design process. In this review paper, I summarize the technology and describe the ''best practices'' for the fatigue analysis of a wind turbine component. The paper focuses on U.S. technology, but cites European references that provide important insights into the fatigue analysis of wind turbines.

  4. Fatigue in Steel Structures under Random Loading

    DEFF Research Database (Denmark)

    Agerskov, Henning

    1999-01-01

    types of welded plate test specimens and full-scale offshore tubular joints. The materials that have been used are either conventional structural steel with a yield stress of ~ 360-410 MPa or high-strength steel with a yield stress of ~ 810-1010 MPa. The fatigue tests and the fracture mechanics analyses......Fatigue damage accumulation in steel structures under random loading is studied. The fatigue life of welded joints has been determined both experimentally and from a fracture mechanics analysis. In the experimental part of the investigation, fatigue test series have been carried through on various...... have been carried out using load histories, which are realistic in relation to the types of structures studied, i.e. primarily bridges, offshore structures and chimneys. In general, the test series carried through show a significant difference between constant amplitude and variable amplitude fatigue...

  5. Parallel monostrand stay cable bending fatigue

    DEFF Research Database (Denmark)

    Winkler, Jan Pawel

    of damage and replacement of bridge stay cables due to wind and traffic-induced fatigue. The understanding of fatigue mechanisms in most steel structures is well established. However, in the case of cables composed of steel strands, many important aspects related with bending fatigue remain to be clarified......This dissertation investigates the bending fatigue response of high-strength steel monostrands and multistrand stay cables to cyclic transverse deformations. Increasing bridge stock numbers and a push for longer cable-supported span lengths have led to an increased number of reported incidents...... associated with variable loading, and different testing procedures. As most of the contemporary stay cables are comprised of a number of individual highstrength steel monostrands, the research study started with an extensive experimental work on the fatigue response of a single monostrand to cyclic flexural...

  6. Fatigue in patients receiving maintenance dialysis: a review of definitions, measures, and contributing factors.

    Science.gov (United States)

    Jhamb, Manisha; Weisbord, Steven D; Steel, Jennifer L; Unruh, Mark

    2008-08-01

    Fatigue is a debilitating symptom or side effect experienced by many patients on long-term dialysis therapy. Fatigue has a considerable effect on patient health-related quality of life and is viewed as being more important than survival by some patients. Renal providers face many challenges when attempting to reduce fatigue in dialysis patients. The lack of a reliable, valid, and sensitive fatigue scale complicates the accurate identification of this symptom. Symptoms of daytime sleepiness and depression overlap with fatigue, making it difficult to target specific therapies. Moreover, many chronic health conditions common in the long-term dialysis population may lead to the development of fatigue and contribute to the day-to-day and diurnal variation in fatigue in patients. Key to improving the assessment and treatment of fatigue is improving our understanding of potential mediators, as well as potential therapies. Cytokines have emerged as an important mediator of fatigue and have been studied extensively in patients with cancer-related fatigue. In addition, although erythropoietin-stimulating agents have been shown to mitigate fatigue, the recent controversy regarding erythropoietin-stimulating agent dosing in patients with chronic kidney disease suggests that erythropoietin-stimulating agent therapy may not serve as the sole therapy to improve fatigue in this population. In conclusion, fatigue is an important and often underrecognized symptom in the dialysis population. Possible interventions for minimizing fatigue in patients on long-term dialysis therapy should aim at improving health care provider awareness, developing improved methods of measurement, understanding the pathogenesis better, and managing known contributing factors.

  7. Fatigue in the presence of c