发动机活塞热疲劳模拟试验装置

１概述发动机作为车辆的心脏，其可靠性直接影响到车辆的性能。在实际应用中，活塞承受反复的热负荷，易产生裂纹等故障。因而在发动机设计和制造过程中用疲劳试验的方法来确定活塞的极限强度是个重要环节。为能在较短时间内，以小规模、低成本的方式及时获得新产品的试验...

扑火中热过劳伤害及预防调节措施

扑救森林火灾是一项艰苦的工作,移动范围大,经常在险峻的地带和高海拔地区工作。通常天气炎热干燥,同时,由于人体表面暴露在火焰前面,更加受到热的熏烤。讨论火场环境使扑火队员产生热过劳伤害的危险,以及扑火队员把这种危险减少到最小限度,应该做些什么。

關於工業企業中勞動保護組織机構問題的意见

解放以來,在党和政府保護劳動的政策指導下,廠礦企業中的劳動保護工作逐步開展起來,企業行政方面的劳動保護職能机構也紛紛建立起來,並且隨着國家大規模經济建設的開展,企業劳動保護工作逐步走向計劃化,劳動保護組織机構也更趨健全。劳動保護工作已獲得重大成就。劳動保護組織机構的建立与健全本身也是劳動保護工作重要成績的一个方面。經驗証明,在進行劳動保護工作过程中,必須經常注意加强对企業劳動保護組織机構的領導。但是,在这方面,目前尚存在着一些問题,甚至有的問題还有爭执。个别企業單位採取的不是加强劳動保護組織机構的措施。

降白汤治疗骨髓增殖性疾病(白细胞增多型)1例报道

骨髓增殖性疾病,又称骨髓增殖性肿瘤,包括真性红细胞增多症、原发性骨髓纤维化、原发性血小板增多症、慢性粒细胞白血病等,这些疾病临床表现相似,以骨髓过度增殖为特点。而临床中慢性粒细胞白血病及骨髓纤维化以白细胞增多为主。中医将此病归于热劳的范畴,根据中医辨证论治原则,中医将此病辨为气滞血瘀,痰凝毒结型。治则以行气化瘀,化痰散结为主,方药使用自拟降白汤进行治疗,效果显著。

Temperature evolution and fatigue life evaluation of AZ31B magnesium alloy based on infrared thermography

The surface temperature of extruded AZ31B alloy plate was measured by infrared thermograph in air during tension and high-cycle fatigue tests. The mechanism of heat production was discussed and the value of critical fatigue damage temperature was calculated according to the P—ΔT curve. Results show that the variation trend of temperature is different between tension and fatigue tests. The temperature evolution in tension test consists of four stages： linear decrease, reverse linear increase, abrupt increase, and final drop. The initial decrease of temperature is caused by thermal elastic effect, which is corresponding to the elastic deformation in tension progress. When cyclic loading is above the fatigue limit, the temperature evolution mainly undergoes five stages： initial increase, steep reduction, steady state, abrupt increase, and final drop. The peak temperature in fatigue test is caused by strain hardening that can be used to evaluate the fatigue life of magnesium alloy. The critical temperature variation that causes the fatigue failure is 3.63 K. When ΔT≤3.63 K, the material is safe under cyclic loading. When ΔT3.63 K, the fatigue life is determined by cycle index and peak temperature.

劳盆地深海热液喷口沉积物中细菌多样性研究

采用PCR-RFLP技术调查了劳盆地深海热液喷口两位点沉积物中的细菌多样性。结果表明,在劳盆地深海热液喷口沉积物环境中细菌多样性十分丰富,样品DY1中发现6个细菌类群,DY2中则存在4个细菌类群,其中Gammaproteobacteria细菌亚群和Epsilonproteobacteria细菌亚群在两文库中均占据最大比例,为沉积物样品中的优势菌群。另外,在克隆文库中还发现了一些与数据库中的已知序列同源性较低的类群,从而说明劳盆地深海热液喷口沉积物中存在特有的微生物种属。

左归丸联合西药治疗再生障碍性贫血随机平行对照研究

[目的]观察左归丸联合西药治疗再生障碍性贫血疗效。[方法]使用随机平行对照方法,将104例住院患者按抽签法随机分为两组。对照组52例,环孢素A 5mg/kg/次,3次/d。康力龙6mg/次,3次/d。治疗组52例左归丸(熟地25g,山药15g,山茱萸、枸杞子各12g,鹿角胶6g,菟丝子15g,杜仲12g,当归、肉桂、丹皮各10g),水煎200mL,1剂/d,早晚温服。西药治疗同对照组。连续治疗3个月为1疗程。观测临床症状、血常规、骨髓像、不良反应。治疗1疗程,判定疗效。[结果]治疗组52例,基本痊愈21例,缓解13例,明显进步15例,无效3例,总有效率94.23%。对照组52例,基本痊愈12例,缓解9例,明显进步22例,无效9例,总有效率82.69%。临床疗效治疗组优于对照组(P<0.05)。[结论]左归丸加减治疗再生障碍性贫血疗效显著,值得推广。

Fatigue behavior of AZ31B magnesium alloy electron beam welded joint based on infrared thermography

Fatigue behavior of AZ31B magnesium alloy electron beam welded joint undergoing cyclic loading was investigated by infrared thermography. Temperature evolution throughout a fatigue process was presented and the mechanism of heat generationwas discussed. Fatigue limit of the welded joint was predicted and the fatigue damage was also assessed based ontheevolution of the temperatureand hotspot zone on the specimen surfaceduring fatigue tests. The presented results show that infrared thermography can not onlyquicklypredict the fatigue behavior of the welded joint, but also qualitatively identify the evolution of fatigue damage in real time. It is found that the predicted fatigue limit agrees well with the conventionalS-Nexperimental results. The evolution of the temperatureand hotspot zone on the specimen surface can be an effectivefatigue damage indicatorfor effectiveevaluationof magnesium alloy electron beam welded joint.

Effects of Si addition on microstructure, mechanical and thermal fatigue properties of Zn-38Al-2.5Cu alloys

The influence of Si addition on microstructure, mechanical properties and thermal fatigue behavior of Zn-38Al-2.5Cu alloys was investigated. The results show that constitutional supercooling of ZA38 alloys is formed because of the Si addition. Zn-38Al-2.5Cu-0.55Si alloy shows the dramatically refined microstructure and the best mechanical properties. When the Si addition exceeds 0.55%,αdendrites develop and Si phases become larger and aggregate along the dendrites boundaries, decreasing the mechanical properties. Oxides and pits formed by the plastic deformation are the main factors of cracks initiation. During the early stage of crack propagation, the cracks grow at a high speed well described by Paris law because of the porous and loose oxide, and mainly propagate along the dendrites boundaries. During the slow-growth stage, secondary cracks share the energy of crack growth, delaying the propagation of cracks, and the cracks propagate and fracture by the mixture of intergranular and transgranular modes.

Thermal fatigue crack growth behavior of ZCuAlFeMn alloy strengthened by laser shock processing

The effect of laser shock processing(LSP) on the hardness, surface morphology, residual stress, and thermal fatigue properties of a ZCuAl10Fe3Mn2 alloy was investigated to improve the thermal fatigue performance and decrease the surface crack of high-temperature components. The microstructure and crack morphology were analyzed by scanning electron microscopy(SEM) and energy dispersive spectroscopy(EDS). The results showed that laser shock could significantly improve the thermal fatigue performance of the alloy at a pulse energy of 4 J. Under the effect of thermal stress and alternating stress, microstructure around the specimen notch was oxidized and became porous, leading to the formation of multiple micro-cracks. The micro-cracks in the vertical direction became the main cracks, which mainly expanded with the conjoining of contiguous voids at the crack tip front. Micro-cracks in other directions grew along the grain boundaries and led to material shedding.

Effect of preload force on heat generation of fatigue crack in ultrasonic infrared thermography

The heat generation behaviors of fatigue crack are deeply investigated under different preload forces combing numerical simulation and experiment.Firstly,a multi-contact simulation model is applied to stimulate the crack surfaces contact and the horn-sample contact under ultrasonic excitation for calculating the temperature fields.Then,the ultrasonic infrared thermography testing and the microscope testing are carried out for the heat generation and the plastic deformation behaviors of crack region under different preload forces.On this basis,an indirect observation method based on dots distribution is proposed to estimate the plastic deformation on crack contact surfaces.The obtained results show that the temperature rise of crack region increases with the increase of preload force when the preload force is less than 250 N,while the temperature rise rapidly declines due to the plastic deformation on crack contact surfaces and the inhibition effect when the preload force is 280 N.Moreover,the plastic deformation does not lead to the crack propagation,but reduces the detection repeatability of fatigue crack.This work provides an effective method for optimizing testing conditions in practical testing processes,which will be helpful to the establishment of testing standards for batches of test objects in ultrasonic infrared thermography testing.

Thermo-mechanical fatigue reliability optimization of PBGA solder joints based on ANN-PSO

Based on a method combined artificial neural network (ANN) with particle swarm optimization (PSO) algorithm, the thermo-mechanical fatigue reliability of plastic ball grid array (PBGA) solder joints was studied. The simulation experiments of accelerated thermal cycling test were performed by ANSYS software. Based on orthogonal array experiments, a back-propagation artificial neural network (BPNN) was used to establish the nonlinear multivariate relationship between thermo-mechanical fatigue reliability and control factors. Then, PSO was applied to obtaining the optimal levels of control factors by using the output of BPNN as the affinity measure. The results show that the control factors, such as print circuit board (PCB) size, PCB thickness, substrate size, substrate thickness, PCB coefficient of thermal expansion (CTE), substrate CTE, silicon die CTE, and solder joint CTE, have a great influence on thermo-mechanical fatigue reliability of PBGA solder joints. The ratio of signal to noise of ANN-PSO method is 51.77 dB and its error is 33.3% less than that of Taguchi method. Moreover, the running time of ANN-PSO method is only 2% of that of the BPNN. These conclusions are verified by the confirmative experiments.

Effect of nano-sized Al2O3 reinforcing particles on uniaxial and high cycle fatigue behaviors of hot-forged AZ31B magnesium alloy

The effect of hot-forging process was investigated on microstructural and mechanical properties of AZ31 B alloy and AZ31 B/1.5 vol.%Al2 O3 nanocomposite under static and cycling loading. The as-cast alloy and composite were firstly subjected to a homogenization heat treatment at 450 ℃ and then an open-die forging at 450 ℃. The results indicated that the presence of reinforcing particles led to grain refinement and improvement of dynamic recrystallization. The forging process was more effective to eliminate the porosity in the cast alloy workpiece. Microhardness of the forged composite was increased by up to 80% and 16%, in comparison with those of the cast and forged alloy samples, respectively. Ultimate tensile strength and maximum tensile strain of the composite were improved by up to 45% and 23%, compared with those of the forged alloy in similar regions. These enhancements were respectively 50% and 37% in the compression test. The composite exhibited a fatigue life improvement in the region with low applied strain;however, a degradation was observed in the high applied strain region. Unlike AZ31 B samples, tensile, compressive and high cycle fatigue behaviors of the composite showed less sensitivity to the applied strain, which can be attributed to the amount of porosity in the samples before and after the hot-forging.

Fatigue strength and microstructure evaluation of Al 7050 alloy wires recycled by spray forming,extrusion and rotary swaging

Recycled high-strength aluminum alloys have limited use as structural materials due to poor mechanical properties. Spray forming remelting followed by hot extrusion is a promising route for reprocessing 7 xxx alloys. The 7050 alloy machining chips were spray formed, hot extruded, rotary swaged and heat-treated in order to improve mechanical properties. Microstructures, tensile properties and fatigue strength results for a 2.7 mm-diameter recycled wire are presented. Secondary phases and precipitates were investigated by XRD, SEM, EBSD, TEM and DSC. As-swaged and heat-treated(solution and aging) conditions were evaluated. Mechanical properties of both conditions outperformed AA7050 aerospace specification. Substantial grain refinement resulted from the extensive plastic deformation imposed by rotary swaging. Refined micrometric and sub-micrometric Al grains, as well as coarse and fine intermetallic precipitates were observed. Subsequent solution treatment resulted in a homogeneous, recrystallized and equiaxed microstructure with grain size of 9 μm. Nanoscale GP(I) zones and η′ phase precipitates formed after aging at 120 ℃, imparting higher tensile(586 MPa) and fatigue(198 MPa) strengths.

High cyclic fatigue performance of Al-Cu-Mg-Ag alloy under T6 and T840 conditions

High cyclic fatigue(HCF)behavior of an AA2139alloy belonging to Al-Cu-Mg-Ag system in T6and T840conditionswas examined.The T840treatment involving cold rolling with a40%reduction prior to peak ageing provides an increase in tensilestrength compared with the T6condition.However,fatigue lifetime for two material conditions was nearly the same since there isweak effect of thermomechanical processing on micro-mechanisms of crack initiation and growth.

Effect of annealing treatment on microstructure and fatigue crack growth behavior of Al–Zn–Mg–Sc–Zr alloy

Al-Zn-Mg-Sc-Zr alloy samples were annealed to four different states （under-aging, peak-aging, over-aging and double-aging） and then thoroughly investigated by means of electron backscatter diffraction （EBSD）, transmission electron microscopy （TEM）, scanning electron microscopy （SEM）, tensile and fatigue crack growth rate tests to explore the influence of annealing treatment on microstmcture and fatigue crack growth behavior. The results indicate that Al3（Sc,Zr） particles can effectively refine grains and enhance tensile properties and fatigue properties. After annealing treatment, the under-aged sample and double-aged sample obtained average grain sizes of 4.9473 and 4.1257 μm, and the maximum value of yield/tensile strength （561 MPa/581 MPa） was obtained in peak-aged state. In the Paris region, fatigue crack growth rate, crack deflection and bifurcation, crack blunting and inter/trans-granular propagation were discussed based on data fitting and Laird model and Griffith theory. And the results show that the under-aged sample possesses the best resistance to fatigue crack propagation and the most tortuous and bifurcated crack path. For all samples, the fatigue crack growth rate in the rupture region was inversely proportional to yield strength.

Cyclic deformation behaviors of Ti-46Al-2Cr-2Nb-0.15B alloy during thermo-mechanical fatigue tests

Thermo-mechanical fatigue tests were carried out on the gamma-TiAl alloy in the temperature range of 500-800℃ under mechanical strain control m order to evaluate its cyclic deformation behaviors at elevated temperature. Cyclic deformation curves, stress-strain hysteresis loops under different temperature--strain cycles were analyzed and dislocation configurations were also observed by TEM. The mechanisms of cyclic hardening or softening during thermo-mechanical fatigue （TMF） tests were also discussed. Results showed that thermo-mechanical fatigue lives largely depended on the applied mechanical strain amplitudes, applied types of strain and temperature. On the hysteresis loops appeared two apparent asymmetries： one was zero asymmetry and the other was tensile and compressive asymmetry. Dislocations configuration and slip behaviors were contributed to cyclic hardening or cyclic softening.

Long term performance of warm mix asphalt versus hot mix asphalt

The fatigue behavior, indirect tensile strength （ITS） and resilient modulus test results for warm mix asphalt （WMA） as well as hot mix asphalt （HMA） at different ageing levels were evaluated. Laboratory-prepared samples were aged artificially in the oven to simulate short-term and long term ageing in accordance with AASHTO R30 and then compared with unaged specimens. Beam fatigue testing was performed using beam specimens at 25 ℃ based on AASHTO T321 standard. Fatigue life, bending stiffness and dissipated energy for both unaged and aged mixtures were calculated using four-point beam fatigue test results. Three-point bending tests were performed using semi-circular bend （SCB） specimens at -10 ℃ and the critical mode I stress intensity factor K1 was then calculated using the peak load obtained from the load-displacement curve. It is observed that Sasobit and Rheofalt warm mix asphalt additives have a significant effect on indirect tensile strength, resilient modulus, fatigue behavior and stress intensity factor of aged and unaged mixtures.

“有革必調,有余必抽”

我們在党的正确领导和总路线的光輝照耀下,今年以来,积极开展了以“四化”为中心的技术革新、技术革命运动,并且从各方面采取措施,把劳动力节約出来。这样,不仅解决了劳动力不足的问题,而且还抽調劳动力支援了兄弟单位。从一月到六月十日,全局共节約出劳动力五百四十二人,到五月十九日,我們已经提前四十二天超额完成了上半年的任务。我們的主要措施有以下几項: 有革必調 有余必抽我们随着技术革新、技术革命运动的逐步开展,那里有革新,就在那里調整劳动組織:对多余的劳动力和机具,当抽就抽,当收就收。这样做不仅节省了劳动力,而且巩固了革新战果,

《悟医吟草》连载

肿瘤篇恶性肿瘤(序)时病恶癌人悸忡,癥瘕积聚状相同。血瘀忧郁藏因果,中药中医本可攻。注:1、闻癌失色是当今人们普遍的心态,然而随着科技的发展,致癌的因素不断增多,如:光、化学、物理、食品、环境等等,因此,癌肿病人也不断增多。现代医学采用手术、化疗、放疗的疗法,只凭单一攻杀,并无考虑到机体的全面变化。