EXPERIENCE WITH THERMOMECHANICAL FATIGUE UNDER SERVICE-TYPE LOADING

The thermomechanical fatigue behaviour of different high temperature alloys has been investigated and is under investigation respectively. The creep-fatigue behaviour of heat resistant steels was investigated by long-term service-type strain cycling tests simulating thermomechanical fatigue (TMF-) loading conditions at the heated surface of e.g. turbine rotors. Single-stage as well as three-stage cycles leads to similar results at the application of the damage accumulation rule. Life prediction which simulates typical combinations of cold starts, warm starts and hot starts has been established successfully for isothermal service-type loading and will be exceeded for thermomechanical loading. Long-term thermomechanical fatigue testing of Thermal Barrier Coating systems show typical delamination damage. An advanced TMF cruciform testing system enables complex multiaxial loading.

Influencing factors of fatigue in young and middle-aged patients with coronary heart disease:a cross-sectional study

Objective:To examine the present state of fatigue in young and middle-aged patients with coronary heart disease(CHD)and to identify the elements that may be affecting it.Methods:From December 2020 to June 2021,240 young and middle-aged patients with CHD who were being treated in the cardiology department of a tertiary care hospital in Suzhou were chosen using a convenience sampling method in order to gather data on the patients’sociodemographic status,fatigue,social support,and stress.Results:Of the 240 disseminated questionnaires,220 valid responses were returned,resulting in an effective recovery rate of 91.67%.The frequency of exhaustion was 51.8%,and the fatigue score was(5.27±2.77).The stress score was(11.15±3.36),while the overall social support score was(39.13±4.72).Binary logistic regression analysis indicated that age,exercise,staying up late,stress,social support,high-sensitivity troponin T,high-density lipoprotein,and ejection fraction were independent risk factors for fatigue in young and middle-aged patients with CHD(P<0.05).Conclusions:Fatigue is more prevalent in young and middle-aged patients with CHD.Clinical nurses can create a unique management plan for patients based on their lifestyle and behavioral patterns,stress levels,social support,and clinical signs to reduce fatigue.

Symptom experience in patients with cancer-related fatigue:A systematic review and meta-synthesis

To understand the real experiences of patients with cancer-related fatigue and to promote quality of life,the researchers used computer searches of PubMed,EMbase,CINAHL,PsycINFO,Web of Science,and China National Knowledge Infrastructure,China Biology Medicine disc,Wanfang Data,China Science and Technology Journal Database for relevant qualitative studies from the inception to November 1,2021.The results showed that a total of 16 papers were included,and 57 outcomes were distilled into 9 categories,which were pooled into four integrated outcomes,such as somatic,psychological and social support and so on.It is concluded that patients with cancer-related fatigue are not only in the midst of multidimensional,unspeakable somatic experiences,and complex psychological experiences,they are also hindered in coping with fatigue symptom and social life.Therefore,healthcare professionals should provide health interventions and psychological support to those patients whenever possible.

Fatigue behavior of basalt-aramid and basalt-carbon hybrid fiber reinforced polymer sheets

In order to study the fatigue failure mode and fatigue life laws of basalt-aramid and basalt-carbon hybrid fiber reinforced polymer （ FRP ） sheets, fatigue experiments are carried out, considering two hybrid ratios of 1 ： 1 and 2：1 under different stress levels from 0.6 to 0.95. The results show that fractures occur first in carbon fibers or aramid fibers for the specimens with hybrid ratio of 1： 1, namely B1A1 and B1C1, while a fracture occurs first in basalt fibers for the specimens with a hybrid ratio of 2： 1, namely B2A1 and B2C1. The fatigue lives of the hybrid FRP sheets increase with the improvement of the content of carbon fibers or aramid fibers, and the influence of the carbon fibers content improvement to fatigue life is more significant. The fatigue performance of B2A1 is relatively worse, while the fatigue performance of B1C1 and B2C1 is relatively better. Finally, a new fatigue stiffness degradation model with dual variables and double inflection points is presented, which is applicable to both hybrid and normal FRP sheets.

PRE-CORROSION FATIGUE NOTCH FACTOR

The notched and smooth specimens of aluminum alloy LC4CS soaked in EXCO solution for different time are tested under the constant amplitude cyclic loading to obtain S-N curves and fatigue notch factors with different pre-corrosion time. By analyzing the corrosion process of LC4CS specimens in EXCO solution, the influ- ence mechanism of corrosion on fatigue notch factor is expounded. Then, a two-parameter model used to describe the change of corrosion fatigue notch factor with time is established and verified by experiment. The results show that the pre-corrosion fatigue notch factor of LC4CS material decreases at first and then increases with the increasing pre-corrosion time. The inflection point appears at the beginning of denudation stage.

Squat,Stoop,or Semi-squat:A Comparative Experiment on Lifting Technique

There are actually no sufficient data for lifting technique assessment.A laboratory study was undertaken to determine the effect of 3 regular lifting techniques on erector muscle activation,cardiovascular strain and subjective response.Thirty student volunteers participated in the study,and were required to lift a weight with different techniques.Stoop-,squat-,semi-squat-lifting resulted in 3,2 and 1 time of the highest percentage of the maximum voluntary electrical activation(MVE%) respectively.In the same order,the lowest median frequency(MF) existed 1,1 and 2 times.Muscle fatigue was 4 times in squat,36 in semi-squat and 43 in stoop lifting.Heart rate was the highest in squat and lowest in stoop respectively,with a middle level in semi-squat lifting.It may be recommended to adopt mainly the semi-squat technique for daily lifting works.For heavy lifting,it should use the squat technique.Stoop lifting may also be used alternatively but for light things.

Study on Hydrogen Environment Fatigue Test System and Correlative Fatigue Test of Hydrogen Storage Vessel

A 70 MPa hydrogen environment fatigue test system has been designed and applied in the manufacture of a hydrogen storage vessel. The key equipment is a 80 MPa flat steel ribbon wound high pressure hydrogen storage vessel. A reasonable stress distribution has been realized, which is low stress on the liner of the pressure vessel and even stress on the flat ribbon layers. This optimal stress distribution is achieved through the adjustment of the prestress in flat steel ribbons. A control system for the fatigue test system has also been designed. It consists of a double control model, manual control and automatic control, to satisfy different experiment requirements. The system is the only one which can be used in the real hydrogen environmental fatigue test system in China. An experiment for a 70 MPa onboard composite material hydrogen vessel has been carried out on the system. The experimental results from this test are in close agreement with the practical operating conditions.

表面肌电测试技术在研究生实验教学中的应用

利用表面肌电测试技术测量肌肉疲劳,开设研究型实验教学项目,让学生充分发挥主观能动性,独立设计实验方案,独立判断实验方案的合理性,以及运用基本实验技能进行实验操作和数据分析,熟练掌握表面肌电测试方法。该实验教学项目充实了兵器专业研究生的实验教学内容,能够培养学生的科学思维、创新精神和具体实验技能,为学生今后的科研和工作提供必要的实验手段。

卒中后疲劳患者疲劳体验及应对策略的质性研究

目的深入了解卒中后疲劳患者疲劳体验及应对策略,为制定针对性护理方案提供参考。方法采用描述性质性研究,按照目的抽样法选取16例卒中后疲劳患者进行半结构访谈,运用主题分析法对访谈资料进行分析与整理。结果卒中后疲劳患者疲劳体验共提炼出4个主题:卒中后疲劳特征、日常生活陷入紊乱状态、与他人讨论疲劳的反馈、渴望获得支持与理解。疲劳应对策略共提炼出2个主题:努力克服及适应疲劳、逃避或放弃应对疲劳。结论医护人员应重视卒中后疲劳患者的疲劳筛查与评估,鼓励患者正确应对疲劳,并采取多渠道的综合干预策略,缓解患者的疲劳症状。

卒中后疲劳患者疲劳体验质性研究的Meta整合

背景既往研究显示,脑卒中患者卒中后疲劳(PSF)发生率高达25%~85%,持续不断的疲乏感严重影响患者日常生活和康复进程,因此亟需了解此类患者的心理体验和需求,但既往已进行的单一的质性研究结果可能不具有代表性。目的系统评价和整合卒中后疲劳患者疲劳体验的质性研究,为构建PSF患者疲劳管理策略提供依据。方法计算机检索PsycINFO、PubMed、Web of Science、CINAHL、Cochrane Library、Scopus、澳大利亚安娜布里格斯研究所(JBI)循证卫生保健数据库及中国知网、万方数据知识服务平台、维普网、中国生物医学文献数据库,搜集与PSF患者疲劳体验相关的质性研究。检索时限为建库至2023-07-05。采用澳大利亚JBI循证卫生保健中心质性研究质量评价标准(2016)进行质量评价,并采用汇集性整合的方法进行Meta整合。结果共纳入10篇文献,提炼出22个主要结果,归纳为8个类别,综合为4个整合结果:对PSF的认知严重匮乏;存在错综复杂的负性身心体验;PSF的自我调适方式多样;存在多种PSF康复需求。结论PSF患者对疲劳认知不足且存在明显负性身心体验,因此应早期识别和筛查PSF患者,强化对患者的疲劳教育并为其制订个性化疲劳管理策略,同时应重视发挥社区和家庭在PSF患者疲劳管理中的作用,使其与医护人员一同为PSF患者提供良好的康复环境。

血液透析患者疲劳体验及管理质性研究的Meta整合

目的系统评价与整合血液透析患者疲劳体验及管理的质性研究。方法计算机检索Cochrane Library、Web of Science、PubMed、CINAHL、Embase、Scopus、CBM、知网、万方、维普数据库建库至2023年12月发表的关于血液透析患者疲劳体验或管理的质性研究,采用汇集性整合方法对结果进行Meta整合。结果共纳入9篇文献,提炼出38个结果,形成10个类别,汇总成4个整合结果:血液透析患者对疲劳的认知、疲劳产生的影响、患者自我管理策略、疲劳管理需求及挑战。结论血液透析患者疲劳管理存在认知缺乏、负性情绪影响、自我管理策略不全面、干预措施不精准等障碍,医疗机构应构建多样化管理策略并提供全面支持,完善患者自我管理策略,延长血液透析患者生存周期并提高其生活质量。

海洋食品酶解物改善精神疲劳功能性评价的综合实验设计

该文设计了以小鼠模型评价海洋食品酶解物对改善精神疲劳营养功能的创新性综合实验,以海参和牡蛎两种海洋生物资源为原料,通过酶解法制备了海参酶解物和牡蛎酶解物,测定了两种酶解物的氨基酸组成,探究了两种酶解物对皮质酮所致精神疲劳模型小鼠耐力、焦虑样行为、抑郁样行为以及神经递质水平的影响。结果表明海参酶解物和牡蛎酶解物均可显著提高精神疲劳小鼠的耐力表现,并改善焦虑样行为和抑郁情绪,其中,海参酶解物在改善焦虑样行为方面更显著,而牡蛎酶解物在改善抑郁情绪方面更显著。进一步研究发现两种酶解物通过调节神经递质水平改善精神疲劳。该综合实验结合了海洋生物资源精深加工技术、食品检验与分析、食品营养学、功能性食品等多领域实验技术,有助于提高学生的学习积极性、深化学生所学理论知识、培养其创新思维和实验技能。

基于品质因数的超声刀刀头疲劳振动评价研究

目的:针对超声刀刀头疲劳效能评价存在的难题,提出基于品质因数的超声刀刀头疲劳振动评价方法。方法:首先,搭建由电源模块、三轴移动模块、超声刀夹持模块和控制模块组成的可实现重复切割操作的超声刀疲劳试验台。其次,采用该试验台对10台某品牌超声刀实施疲劳试验,在疲劳试验的5个阶段(即未切割、500次切割后、1000次切割后、2000次切割后和3000次切割后)对超声刀刀头振动进行非接触式测量并计算其品质因数。最后,计算各阶段试验的平均切割速度和血管凝闭爆破压,以验证基于品质因数的超声刀刀头疲劳振动评价方法的有效性。结果:试验表明,品质因数指标能够有效地反映超声刀刀头的疲劳退化特征,而平均切割速度和血管凝闭爆破压由于测量过程中的不确定性因素不易控制,很难对超声刀刀头的疲劳退化水平进行有效评价。结论:提出的基于品质因数的评价方法可直接对超声刀刀头的疲劳振动进行精准量化评价。

王凌教授从“虚-痰-郁-火”辨证治疗恶性肿瘤放化疗及靶向治疗后虚劳经验

恶性肿瘤是虚劳的主要病因,放化疗、靶向治疗虽有抗肿瘤功效,但其副作用常加重虚劳证候。王凌教授辨证治疗恶性肿瘤放化疗及靶向治疗后虚劳证候,以“脏腑气血阴阳诸虚劳损”为病变之本,虚性证素包括肾精不足、脾胃虚损、肺肾阴亏,实性证素为湿浊、痰浊、气郁、阴火,病性本虚标实,“气阴两虚、痰湿郁火”为基本病机。补肾填精、健脾益胃、清热润肺、化湿祛痰、疏肝柔肝为主要治法,扶正祛邪,燮理阴阳,以平为期。

齐元富教授益气补血法治疗癌因性疲乏经验谈

山东省中医院名老中医齐元富教授从医几十年积累了大量宝贵临床经验,在以益气补血法治疗癌因性疲乏方面颇有心得。他认为心、肝与癌因性疲乏密切相关,是诊治重点,并且以益气补血为治则,以标本兼治为目的,自拟方益气补血汤,在临床上取得了不错疗效。齐教授选择益气补血汤对症治疗,不仅针对患者的症状,同时兼顾其肿瘤术后的防治,用药精专,在使用益气补血汤原方基础上,灵活加减,附验案一则以佐证。

W形弹条疲劳断裂分析及对策

W形弹条在疲劳检验过程中发生断裂,以断裂弹条为研究对象,采用金相显微镜、扫描电子显微镜(Scanning Electron Microscope,SEM)、洛氏硬度计、布氏硬度计等,对断裂弹条及同批次60Si2Mn原材料进行力学性能、金相组织、脱碳层、断口扫描、硬度等试验,分析弹条断裂原因,并提出改进措施。结果表明:该60Si2Mn原材料的力学性能、脱碳层、布氏硬度均满足标准要求;距断裂表面约100μm处存在夹杂物,夹杂物中有Ca、Si、P、O、K等元素,为疲劳断裂裂纹源;弹条断裂的根本原因是,弹簧钢浇注过程中结晶器液面发生波动,导致保护渣卷入钢液。原材料进厂增加DS夹杂物级别和非金属夹杂物位置判定后,生产弹条疲劳试验过程未出现断裂。建议TB/T 3395.5—2015《高速铁路扣件第5部分WJ-8型扣件》增加DS夹杂物级别和非金属夹杂物位置指标。

师徒关系对大学生学习倦怠的影响机制:学业浮力和心流体验的作用

为探讨师徒关系对大学生学习倦怠的影响及作用机制,采用师徒关系量表、学业浮力量表、心流体验量表和学习倦怠量表对国内461位在校大学生进行调查。结果表明:(1)师徒关系对大学生学习倦怠具有显著负向影响;(2)学业浮力在师徒关系和大学生学习倦怠之间起部分中介作用;(3)心流体验对师徒关系和大学生学习倦怠的关系起显著调节作用。因此,对于大学生学习倦怠心理和行为的预防和缓解,应从构建高质量师徒关系入手,建立亦师亦友的导学关系;提高其学业浮力水平,培育大学生的抗压和耐挫力;构建良好的课堂体验,激发大学生的心流状态。

多发性骨髓瘤化疗患者自我调节疲乏对化疗耐受能力的影响

目的了解多发性骨髓瘤(MM)化疗患者自我调节疲乏现状,分析其对患者化疗耐受能力的影响。方法采用便利抽样法,抽取2020年1月至2022年1月四川大学华西医院收治的105例MM患者为研究对象,采用自我调节疲乏量表(SRF-S)、癌症体验和效能量表(CEES)、癌症患者自我管理测评量表评估患者自我疲乏、癌症自我管理情况。观察MM化疗患者化疗耐受能力,分析MM化疗患者自我调疲乏对化疗耐受能力的影响。结果本研究共纳入105例MM患者,共发放问卷105份,有效回收100份,有效回收率为95.24%。100例MM患者SRF-S评分为(53.28±11.14)分;CEES量表的癌症体验评分为(46.63±12.82)分,控制效能评分为(35.47±7.51)分;平均自我管理评分为(157.54±20.93)分。化疗耐受能力差组SRF-S评分高于化疗耐受能力良好组,差异有统计学意义(P<0.05);经点二列相关性检验,SRF-S评分与MM化疗患者化疗耐受能力呈正相关(r>0,P<0.01)。结论自我调节疲乏与MM化疗患者的化疗耐受能力存在明显相关性,护理人员可根据患者自我调节疲乏状况实施有效干预,提高化疗耐受能力。

桑蚕蛋白复合粉抗运动疲劳功效研究

为了研究桑蚕蛋白复合粉的抗运动疲劳功效与作用机制,C57BL/6雄性小鼠分为对照组、低剂量组(50 mg/kg·d)、中剂量组(100 mg/kg·d)和高剂量组(200 mg/kg·d),灌胃30天后检测力竭游泳时间和运动疲劳标志性生化指标(血尿素氮、血乳酸、肌乳酸、肝糖原、肌糖原和骨骼肌中抗氧化相关酶活性)。与对照组相比,各剂量蚕蛋白复合粉组小鼠力竭游泳时间显著延长,血尿素氮、血乳酸、肌乳酸水平显著降低,肝糖原、肌糖原含量显著升高,骨骼肌中总抗氧化能力、谷胱甘肽过氧化物酶、超氧化物歧化酶和过氧化氢酶的活性显著升高,脂质过氧化产物丙二醛水平显著降低。桑蚕蛋白复合粉可以通过减少代谢废物乳酸与尿素氮的积累、增加肝糖原和肌糖原的储量、降低骨骼肌的氧化应激水平来发挥抗运动疲劳的功效。

白车身金属3D打印钢板与普通低碳钢异质材料点焊可焊性分析

白车身局部采用金属3D打印钢板进行焊接与连接,但装配后白车身总成的可靠性一直缺乏定量的全面评价结果。采用金属3D打印钢材与普通低碳钢钢板进行点焊试验,首先验证了双脉冲参数点焊工艺规范更适用于3D打印钢板与低碳钢钢板之间的连接。在此基础上,进行了焊点接头拉剪强度、微观组织、白车身行李箱盖总成疲劳强度和耐久性测试试验,验证了实际零件点焊质量的可靠性。试验表明,3D打印钢板与低碳钢钢板点焊接头的抗拉强度与普通钢板点焊试样非常接近;3D打印钢板侧快速生成了熔核,低碳钢与熔核之间形成了钎缝;3D打印钢侧的焊点疲劳强度要大于低碳钢侧,在行李箱盖总成耐久性测试后,其功能性完好无损。研究验证了金属3D打印钢零件可作为零件功能性认证,同时也为其将来逐步成为个性化零件装车提供了技术可能性。