拖拉机座椅振动加速度对驾驶疲劳的影响——以心率增加率和疲劳评价值为指标

为了减轻拖拉机驾驶疲劳,在模拟拖拉机座椅振动的条件下,试验研究了振动加速度对被验者的心率变化及其身体疲劳的影响。结果表明:座椅的垂直加速度azw在0.8～2.0m/s2、且联合加权加速度Aw在1.1～2.3m/s2的范围内,被验者的心率增加率随振动加速度增加逐渐减小,其平均值减小13%;azw在2.0～2.4m/s2、且Aw在2.3～2.7m/s2范围内,被验者的心率增加率减小缓慢,平均减小2%;被验者心率增加率与座椅振动加速度呈二次曲线规律变化,具有密切的相关性;被验者身体各部位的疲劳程度随振动加速度增加而加重,头部和胸背部的疲劳明显高于其它部位。

围手术期疲劳评测量表在甲状腺癌术后疲劳评估中的实证研究

目的研究围手术期疲劳评测量表(ICFS)在甲状腺癌术后疲劳评估的应用价值。方法采用量表调查形式,使用BPOMS、VAS和ICFS,对2016年8月至2017年1月于广东省中医院外科确诊甲状腺癌并行根治性切除术的患者进行调查评估,分析ICFS的信度、效度情况。结果汉化后的ICFS同样适用于甲状腺癌术后疲劳的评测,其信度、效度良好。结论 ICFS将会是临床筛查和评估围手术期术后疲劳的可靠工具,值得进一步研究、推广。

围手术期疲劳评测量表在癌性评估的研究应用

随着生物-心理-社会医学模式的建立，癌症患者生存期延长，患者对生存质量的追求不断提高，疲乏问题日益为人们所重视，癌因性疲乏（Cancer—Related Fatigue，CRF）成为医学研究的热点话题。

基于主观感觉疲劳评估量表和客观测量指标变化相结合的腹部术后疲劳监测

目的研究基于主观感觉疲劳评估量表和客观测量指标变化相结合的腹部术后疲劳监测调查情况。方法采用量表调查形式,使用VAS和ICFS,对2016年9月至2017年2月于广东省中医院外科行四级腹部手术的患者进行调查评估;同时进行血液标本、优势手握力、BMI测定,综合评测以围手术期疲劳评测量表为基础,主、客观指标相结合的术后疲劳评价方法。结果 ICFS与CRP、SOD、PA、优势手握力结合可以方便、快捷、经济、高效地检测术后患者的疲劳。结论采用基于主客观指标相结合的检测方法建立的判别函数能够对术后疲劳进行经济、高效、客观的监测,最大限度地减少全凭主观判断所造成的误差。

汉化简明围术期疲劳评测量表在消化道肿瘤术后患者中的应用效果

目的探讨汉化简明围术期疲劳评测量表(ICFS-10)在消化道肿瘤术后患者中的应用价值。方法选取医院2017年9月—2019年9月160例消化道肿瘤术后患者为研究对象,采用性别、年龄匹配的原则分为对照组和观察组,每组80例。对照组实施常规护理,观察组在汉化简明围术期疲劳测量表指导下制定护理方案,对比两组患者术后癌因疲乏和生活质量改善效果。结果观察组患者感觉、情感、认知/情绪、行为/严重程度评分低于对照组,差异有统计学意义(P<0.05);观察组患者生理功能、情感功能、角色功能、社会功能、认知功能、恶心呕吐、疲乏、疼痛、食欲下降、呼吸困难、睡眠障碍、便秘、腹泻及经济困难及总体生活质量评分均高于对照组,差异有统计学意义(P<0.05)。结论消化道肿瘤患者围术期采用汉化简明疲劳测评量表指导的护理模式,可有效改善患者术后由于症状或疾病所带来的癌因疲乏,提高生活质量。

安全壳管道贯穿件分析评定程序的开发

核电站中存在着一类特殊的管道穿安全壳部件,即安全壳贯穿件。其分析方法与规范要求不同于管道分析。因而,针对CAP1000电站中带封头的安全壳贯穿件,需要一套方法和流程对其进行计算、分析和评定。本文以CAP1000带封头的机械贯穿件为研究对象,经分析、研究及对比,基于通用有限元软件ANSYS,以及轴对称模型非轴对称加载和既定的载荷组合策略完成计算,基于通用文档处理软件Excel完成评定,并且应用VB软件将整个计算和分析流程界面化,开发了一套针对带封头的机械贯穿件进行应力分析和疲劳分析的应用程序。本文中的分析评定方法和流程以及基于该方法而编写的程序准确、可靠,可极大地提高工作效率。

老年肝癌患者肝动脉化疗栓塞术后疲劳恢复影响因素的相关性研究

目的 探讨老年肝癌患者肝动脉化疗栓塞术后疲劳恢复情况及影响因素。方法 采用便利抽样法选取2020年10月~2022年3月在某三级甲等医院住院治疗的老年肝癌患者80例,使用简明围术期疲劳评测量表(ICFS-10)进行调查,分别评估术前1 d、术后1、3、7、14、28 d疲劳发生情况,分析患者术后疲劳恢复的影响因素。结果 80例患者中,术后1 d疲劳评分最高(33.88±7.03)分,此后逐渐下降,术后14、28 d疲劳评分[(23.55±6.21)、(22.09±6.23)分]恢复正常。logistic回归分析显示,年龄、肿瘤转移是老年肝癌患者肝动脉化疗栓塞术后疲劳恢复的影响因素(P <0.05)。结论 老年肝癌患者肝动脉化疗栓塞术后1 d疲劳分值最高,随后逐渐恢复,恢复情况与年龄、肿瘤是否转移密切相关,可以通过积极止痛、有效退热等方法促进患者术后疲劳恢复。

紧张状态下累积性疲劳的短时心电特征分析

目的探索是否存在一种可作为累积性疲劳生物标志物的短时心电特征。方法动态跟踪上海理工大学14名健康被试(男、女各7人,年龄为19~23岁)在参加全国大学生电子设计竞赛期间的心电信号,收集被试的主观疲劳量表评分与睡眠时长,并计算心率变异性、心电熵值、高低频段功率值、平均RR间期等13项心电特征。使用Wilcoxon符号秩检验对被试清醒与疲劳时的心电特征差值进行比较。结果被试在缺少睡眠的情况下主观疲劳程度加深,短时心电特征的高频段功率值、高/低频段功率值比值和庞加莱图长半轴在区分清醒与疲劳状态时有统计学意义(P均<0.05)。结论某些常见的短时心电特征可作为检测累积性疲劳的生物标志物。

Multifractal analysis of surface EMG signals for assessing muscle fatigue during static contractions

This study is aimed at assessing muscle fatigue during a static contraction using multifractal analysis and found that the surface electromyographic （SEMG） signals characterized multiffactality during a static contraction. By applying the method of direct determination ofthef（a） singularity spectrum, the area of the multifractal spectrum of the SEMG signals was computed. The results showed that the spectrum area significantly increased during muscle fatigue. Therefore the area could be used as an assessor of muscle fatigue. Compared with the median frequency （MDF）--the most popular indicator of muscle fatigue, the spectrum area presented here showed higher sensitivity during a static contraction. So the singularity spectrum area is considered to be a more effective indicator than the MDF for estimating muscle fatigue.

Fatigue life evaluation on key components of high-speed railway catenary system

The fatigue load spectrum and operation life evaluation of key components in the catenary system under the high speed train running condition were investigated.Firstly,based on the catenary model and pantograph model,the couple dynamic equations of pantograph–catenary were built with the Lagrange’s method;then the dynamic contact force was obtained by the Newmark method at the train speeds of 250,280 and 300 km/h,respectively.Secondly,the finite element model(FEM)of one anchor section’s catenary was built to analyze its transient response under the contact force as train running;then the loading time history of messenger wire base,steady arm,registration tube,oblique cantilever,and straight cantilever were extracted.Finally,the key components’fatigue spectrum was carried out by the rain-flow counting method,and operation life was estimated in consideration of such coefficients,such as stress concentration,shape and dimension,surface treatment.The results show that the fatigue life of the catenary system reduces with the increasing of train speed;specifically,the evaluated fatigue life of the steady arm is shorter than other components.

Finite Element Simplified Fatigue Analysis Method for a Non-tubular Joint of an Offshore Jacket Platform

This paper proposes the finite element simplified fatigue analysis method for fatigue evaluation of the composite non-tubular joint structure of an offshore jacket subjected to wave loads. The skirt pile sleeve of the offshore jacket, which had been in service, was taken as an example of the non-tubular joint structure. SACS software was used for global analysis of multi-directional wave loads for the jacket platform, and ALGOR software was used to build a finite element model, perform finite element analysis, post-process stress results for acquiring the stress range, and perform fatigue evaluation. The analysis results indicate that the extreme stress range is within the allowable stress range and meets the requirements of DNV code. That means the simplified fatigue analysis method is effective and can be used in fatigue design for the non-tubular joint structure of an offshore jacket.

Subsea rigid jumper design and VIV fatigue evaluation

The purpose of this paper is to present a design procedure for subsea rigid jumper system including strength and fatigue analysis. Special attention gives to a methodology based on DNV-RP-F105 to evaluate jumper fatigue damage caused by vortex induced vibration (VIV). Jumper strength analysis is to determine the jumper con-figuration which can accommodate various load conditions and all possible span lengths driven by installation tole-rances of connected subsea structures. Fatigue analysis includes two parts:thermal fatigue and VIV fatigue. This paper presents the procedure of VIV fatigue damage calculation. An example is given to illustrate above methodologies.

Analysis and Comparison of Safety and Fatigue Comfort of Postal Bicycles Based on Finite Element Method and sEMG

The safety and the fatigue comfort were compared between a domestic and a Japanese postal bicycle. Firstly, the fatigue comfort of these two kinds of bicycles was evaluated by surface electromyographic signal (sEMG) experiment, in which human lower limb muscle groups were research objects, and the average EMG (AEMG) index and median frequency (MF) were chosen as the evaluation indexes. Secondly, the safety of these two kinds of bicycle frames was analyzed and compared by using the finite element analysis. The results show that the riding fatigue comfort of the Japanese postal bicycle is better, and the Japanese postal bicycle frame is more safe and reasonable although both the postal bicycles meet the requirement for strength. Finally, based on the above analysis, the frame structure and related parameters of the domestic postal bicycle were improved with reference to the Japanese postal bicycle and biomechanics theory.

Fatigue damage reliability analysis for Nanjing Yangtze river bridge using structural health monitoring data

To evaluate the fatigue damage reliability of critical members of the Nanjing Yangtze river bridge, according to the stress-number curve and Miner’s rule, the corresponding expressions for calculating the structural fatigue damage reliability were derived. Fatigue damage reliability analysis of some critical members of the Nanjing Yangtze river bridge was carried out by using the strain-time histories measured by the structural health monitoring system of the bridge. The corresponding stress spectra were obtained by the real-time rain-flow counting method. Results of fatigue damage were calculated respectively by the reliability method at different reliability and compared with Miner’s rule. The results show that the fatigue damage of critical members of the Nanjing Yangtze river bridge is very small due to its low live-load stress level.

An Investigation on Low Frequency Fatigue Damage of Mooring Lines Applied in a Semi-Submersible Platform

Assessing the fatigue life of mooring systems is important for deep water structures. In this paper, a comprehensive fatigue analysis is conducted on the mooring lines applied in a semi-submersible platform with special focus on the low frequency(LF) fatigue damage. Several influential factors, including water depth, wave spectral parameters, and riser system, are considered. Numerical simulation of a semi-submersible platform with the mooring/riser system is executed under different conditions, and the fatigue damage of mooring lines is assessed by using the time domain analysis method as a benchmark. The effects of these factors on the mooring line tension and the fatigue damage are investigated and discussed in detail. Research results indicate that the LF fatigue damage only accounts for a very small portion of the total damage, although the LF components dominate the global motion response and the mooring line tension of the semi-submersible platform. However, it is demonstrated that the LF fatigue damage is clearly affected by the influential factors. The increase in water depth and spectral peak periods, and the existence of risers can weaken the contribution of the LF components to the mooring line fatigue damage, while the fatigue damage due to the LF components increases with the increase of significant wave height.

Probabilistic Analysis and Fatigue Damage Assessment of Offshore Mooring System due to Non-Gaussian Bimodal Tension Processes

Both wave-frequency(WF) and low-frequency(LF) components of mooring tension are in principle non-Gaussian due to nonlinearities in the dynamic system.This paper conducts a comprehensive investigation of applicable probability density functions(PDFs) of mooring tension amplitudes used to assess mooring-line fatigue damage via the spectral method.Short-term statistical characteristics of mooring-line tension responses are firstly investigated,in which the discrepancy arising from Gaussian approximation is revealed by comparing kurtosis and skewness coefficients.Several distribution functions based on present analytical spectral methods are selected to express the statistical distribution of the mooring-line tension amplitudes.Results indicate that the Gamma-type distribution and a linear combination of Dirlik and Tovo-Benasciutti formulas are suitable for separate WF and LF mooring tension components.A novel parametric method based on nonlinear transformations and stochastic optimization is then proposed to increase the effectiveness of mooring-line fatigue assessment due to non-Gaussian bimodal tension responses.Using time domain simulation as a benchmark,its accuracy is further validated using a numerical case study of a moored semi-submersible platform.

The Stress Combination Method for the Fatigue Assessment of the Hatch Corner of a Bulk Carrier Based on Equivalent Waves

The stress combination method for the fatigue assessment of the hatch comer of a bulk carrier was investigated based on equivalent waves. The principles of the equivalent waves of ship structures were given, including the determination of the dominant load parameter, heading, frequency, and amplitude of the equivalent regular waves. The dominant load parameters of the hatch comer of a bulk carrier were identified by the structural stress response analysis, and then a series of equivalent regular waves were defined based on these parameters. A combination method of the structural stress ranges under the different equivalent waves was developed for the fatigue analysis. The combination factors were obtained by least square regression analysis with the stress ranges derived from spectral fatigue analysis as the target value. The proposed method was applied to the hatch comer of another bulk carrier as an example. This shows that the results from the equivalent wave approach agree well with those from the spectral fatigue analysis. The workload is reduced substantially. This method can be referenced in the fatigue assessment of the hatch comer of a bulk carrier.

Fatigue life evaluation of girth butt weld within welded cast steel joints based on the extrapolation notch stress method

The fatigue life evaluation of the girth butt weld within the welded cast steel joint was studied based on the extrapolation notch stress method.Firstly,the mesh sensitivity of the finite element model of the welded cast steel joint was analyzed to determine the optimal mesh size.Based on the stress field analysis of the finite element model of the welded cast steel joint at the weld toe and weld root,the sharp model of the extrapolation notch stress method was applied to derive the effective notch stress of the rounded model belonging to the effective notch stress method,in which the key problem is to calculate the extrapolation point C,and the extrapolation point C has an exponential function relationship with the geometric parameters of the welded cast steel joint.By setting different values of geometric parameters,the corresponding value of parameter C is calculated,and then the functional relationship between the extrapolation point C and the geometric parameters can be obtained by the multiple linear regression analysis.Meanwhile,the fatigue life evaluation of the girth butt weld within welded cast steel joints based on the effective notch stress was performed according to the guideline recommended by the IIW(International Institute of Welding).The results indicate that the extrapolation notch stress method can effectively simplify the process of calculating the effective notch stress and accurately evaluate the fatigue life of the girth butt weld within welded cast steel joints.

Fatigue damage evaluation by metal magnetic memory testing

Tension-compression fatigue test was performed on 0.45% C steel specimens.Normal and tangential components of magnetic memory testing signals,Hp(y) and Hp(x) signals,with their characteristics,K of Hp(y) and Hp(x)M of Hp(x),throughout the fatigue process were presented and analyzed.Abnormal peaks of Hp(y) and peak of Hp(x) reversed after loading; Hp(y) curves rotated clockwise and Hp(x) curves elevated significantly with the increase of fatigue cycle number at the first a few fatigue cycles,both Hp(y) and Hp(x) curves were stable after that,the amplitude of abnormal peaks of Hp(y) and peak value of Hp(x) increased more quickly after fatigue crack initiation.Abnormal peaks of Hp(y) and peak of Hp(x) at the notch reversed again after failure.The characteristics were found to exhibit consistent tendency in the whole fatigue life and behave differently in different stages of fatigue.In initial and crack developing stages,the characteristics increased significantly due to dislocations increase and crack propagation,respectively.In stable stage,the characteristics remained constant as a result of dislocation blocking,K value ranged from 20 to 30 A/(m·mm)-1,and Hp(x)M ranged from 270 to 300 A/m under the test parameters in this work.After failure,both abnormal peaks of Hp(y) and peak of Hp(x) reversed,K value was 133 A/(m·mm)-1 and Hp(x)M was-640 A/m.The results indicate that the characteristics of Hp(y) and Hp(x) signals were related to the accumulation of fatigue,so it is feasible and applicable to monitor fatigue damage of ferromagnetic components using metal magnetic memory testing(MMMT).

A Rapid Estimation Method of Structural Fatigue Analysis for a 17k Ton DWT Oil Tanker

Fatigue cracks and fatigue damage have been important issues for ships and offshore structures for a long time.However,in the last decade,with the introduction of higher tensile steel in hull structures and increasingly large ship dimensions,the greater attention should be paid to fatigue problems.Most research focuses on how to more easily access the fatigue strength of ships.Also,the major classification societies have already released their fatigue assessment notes.However,due to the complexity of factors influencing fatigue performances,such as wave load and pressure from cargo,the combination of different stress components,stress on concentration of local structure details,means stress,and the corrosive environments,there are different specifications with varying classification societies,leading to the different results from different fatigue assessment methods.This paper established the Det Norske Veritas（DNV） classification notes ＂fatigue assessment of ship structures＂ that explains the process of fatigue assessment and simplified methods.Finally,a fatigue analysis was performed by use data of a real ship and the reliability of the result was assessed.