Two-stage Strain Recovery of Explosively Welded NiTi/NiTi Shape Memory Alloys Prestrained in Martensitic Phase

The present work aimed to investigate the transformation behavior and strain recovery characteristics of Ni50.2Ti/Ni51Ti shape memory alloys （SMAs） prepared by explosive welding. The differential scanning calorimetry （DSC） results showed that the reverse transformation temperatures and the temperature range of NiTi-NiTi alloys increased with increasing prestrain level. Meanwhile, a two-stage strain recovery over a wide temperature range was obtained.

A method for extracting the preseismic gravity anomalies over the Tibetan Plateau based on the maximum shear strain using GRACE data

The occurrence of earthquakes is closely related to the crustal geotectonic movement and the migration of mass,which consequently cause changes in gravity.The Gravity Recovery And Climate Experiment(GRACE)satellite data can be used to detect gravity changes associated with large earthquakes.However,previous GRACE satellite-based seismic gravity-change studies have focused more on coseismic gravity changes than on preseismic gravity changes.Moreover,the noise of the north–south stripe in GRACE data is difficult to eliminate,thereby resulting in the loss of some gravity information related to tectonic activities.To explore the preseismic gravity anomalies in a more refined way,we first propose a method of characterizing gravity variation based on the maximum shear strain of gravity,inspired by the concept of crustal strain.The offset index method is then adopted to describe the gravity anomalies,and the spatial and temporal characteristics of gravity anomalies before earthquakes are analyzed at the scales of the fault zone and plate,respectively.In this work,experiments are carried out on the Tibetan Plateau and its surrounding areas,and the following findings are obtained:First,from the observation scale of the fault zone,we detect the occurrence of large-area gravity anomalies near the epicenter,oftentimes about half a year before an earthquake,and these anomalies were distributed along the fault zone.Second,from the observation scale of the plate,we find that when an earthquake occurred on the Tibetan Plateau,a large number of gravity anomalies also occurred at the boundary of the Tibetan Plateau and the Indian Plate.Moreover,the aforementioned experiments confirm that the proposed method can successfully capture the preseismic gravity anomalies of large earthquakes with a magnitude of less than 8,which suggests a new idea for the application of gravity satellite data to earthquake research.

Therapeutic Effect of Shaoyao Jiawei Gancao Decoction(芍药加味甘草汤)with Acupoint Application on Chronic Lumbar Muscle Strain and the Recovery of Lumbar Strength

Objective:To study the therapeutic effect of Shaoyao Jiawei Gancao Decoction(芍药加味甘草汤)with acupoint application on chronic lumbar muscle strain and the recovery of lumbar strength.Methods:From August 2018 to August 2019,100 patients with chronic lumbar muscle strain admitted to our hospital were selected and randomly divided into an acupoint application group and a combined group of 50 cases each.The acupoint application group was treated by acupoint application,and the combined group was treated with Shaoyao Jiawei Gancao Decoction(芍药加味甘草汤)based on acupoint application.The indexes scores,VAS scores,ADL scores,ODI scores,lumbar endurance,TCM syndrome scores and the treatment effects of the two groups before and after treatment were statistically analyzed,and TNF-αand TXB2 levels were detected.Results:After treatment,the scores of indexes,VAS,ODI,TCM syndrome,TNF-αand TXB2 in the combined group were lower than those in the acupoint application group,and the ADL score,lumbar endurance and treatment efficiency were higher than those in the acupoint application group,with a statistical difference(P<0.05).Conclusion:Shaoyao Jiawei Gancao Decoction(芍药加味甘草汤)with acupoint application can effectively reduce pain,improve lumbar function,restore lumbar strength,effectively relieve inflammation,with significant effects.

Deep postbuckling and nonlinear bending behaviors of nanobeams with nonlocal and strain gradient effects

In this paper, multi-scale modeling for nanobeams with large deflection is conducted in the framework of the nonlocal strain gradient theory and the Euler-Bernoulli beam theory with exact bending curvature. The proposed size-dependent nonlinear beam model incorporates structure-foundation interaction along with two small scale parameters which describe the stiffness-softening and stiffness-hardening size effects of nanomaterials, respectively. By applying Hamilton's principle, the motion equation and the associated boundary condition are derived. A two-step perturbation method is introduced to handle the deep postbuckling and nonlinear bending problems of nanobeams analytically. Afterwards, the influence of geometrical, material, and elastic foundation parameters on the nonlinear mechanical behaviors of nanobeams is discussed. Numerical results show that the stability and precision of the perturbation solutions can be guaranteed, and the two types of size effects become increasingly important as the slenderness ratio increases. Moreover, the in-plane conditions and the high-order nonlinear terms appearing in the bending curvature expression play an important role in the nonlinear behaviors of nanobeams as the maximum deflection increases.

Characteristics of Deformation and Recovery in Shape Memory Alloy

The mechanical behavior and the effect of pre-strain on recovery behavior of Ti50Ni47Fe3 (at. pct) alloy were investigated systematically by tensile and recovered tests accompanied by electrical resistance measurement. Ti50Ni47Fe3 alloy has different deformation behaviors at different temperature ranges, the deformation curves in different temperature range can be classified into four kinds. The start temperature of recovery increases with the increase of pre-strain. There exists an optimal deformation condition, at which the specimen exhibits maximum free recovery strain. With increasing pre-strain the recovery stress increases and reaches the maximum at 8% pre-strain. R-phase to parent transition offered about 0.2% recovery strain. With pre-strain increasing the recovery stress increases and reaches to the maximum at 8% pre-strain. The recovery stress is corresponding with the critical stress of stress-induced martensitic transformation.

Comparison of microstructures in electroformed and spin-formed copper liners of shaped charge undergone high-strain-rate deformation

The as-formed and post-deformed microstructures in both electroformed and spin-formed copper liners of shaped charge were studied by optical microscopy(OM), electron backscattering Kikuchi patterns(EBSP) technique and transmission electron microscopy(TEM). The deformation was carried out at an ultra-high strain rate. OM analysis shows that the initial grains of the electroformed copper liner are finer than those of the spin-formed copper liners. Meanwhile, EBSP analysis reveals that the fiber texture exists in the electroformed copper liners, whereas there is no texture observed in the spin-formed copper liners before deformation. Having undergone high-strain-rate deformation the grains in the recovered slugs, which are transformed from both the electroformed and spin-formed copper liners, all become small. TEM observations of the above two kinds of post-deformed specimens show the existence of cellular structures characterized by tangled dislocations and subgrain boundaries consisting of dislocation arrays. These experimental results indicate that dynamic recovery and recrystallization play an important role in the high-strain-rate deformation process.

Dynamic recrystallization of electroformed copper liners of shaped charges in high-strain-rate plastic deformation

The microstructures in the electroformed copper liners of shapedcharges after high-strain-rate plastic deformation were in-vestigated by transmission electron microscopy(TEM). Meanwhile, theorientation distribution of the grains in the recovered slug wasexamined by the electron backscattering Kikuchipattern(EBSP)technique. EBSP analysis illustrated that unlike theas-formed electro- formed copper liners of shaped charges the grainorientations in the recovered slug are distributed along randomly allthe directions after undergoing heavily strain deformation athigh-strain rate. Optical microscopy shows a typicalrecrystallization structure, and TEM exam- ination revealsdislocation cells existed in the thin foil specimen. These resultsindicate that dynamic recovery and recrystallization occur duringthis plastic deformation process, and the associated deformationtemperature is considered to be higher than 0.6 times the meltingpoint of copper.

PLASTIC DEFORMATION BEHAVIOR OF ELECTROFORMED COPPER LINER OF SHAPED CHARGE AT DIFFERENT STRAIN RATES

The paper deals with different plastic deformation behavior of electroformed copper liner of shaped charge, deformed at high strain rate (about 1×107s-1) and normal strain rate (4×10-4s-1). The crystallographic orientation distribution of grains in recovered slugs which had undergone high-strain-rate plastic deformation during explosive detonation was investigated by electron backscattering Kikuchi pattern technique. Cellular structures formed by tangled dislocations and sub-grain boundaries consisting of dislocation arrays were detected in the recovered slugs. Some twins and slip dislocations were observed in specimen deformed at normal strain rate. It was found that dynamic recovery and recrystallization take place during high-strain-rate deformation due to the temperature rising, whereas the conventional slip mechanism operates during deformation at normal strain rate.

聚氨酯-泡沫铝复合材料的性能研究

目的制备一种具有可恢复阻尼机制的聚氨酯-泡沫铝(PU-AF)减震复合材料,研究PU-AF减震复合材料的阻尼机制,泡沫铝体积质量对PU-AF静态压缩力学性能、吸能性能的影响。方法将制备的PU-AF复合材料在万能材料试验机上进行单调循环压缩试验,由应力-应变曲线研究复合材料的阻尼机制和吸能性能。结果当泡沫铝体积质量为0.70~0.85 g/cm 3时,在相同应变值下,随着泡沫铝体积质量的增加,PU-AF复合材料的屈服强度、弹性模量均增大。吸能效率在应变为30%以后有所降低,最佳吸能效率对应的应变为25%~35%。结论聚氨酯可以显著提高复合材料的应变恢复率;PU-AF是一种很好的减震复合材料。

滚筒式残膜回收机关键部件应力应变监测系统设计与实验

滚筒式残膜回收机是残膜回收机中的主要机型,其关键部件是否正常运行直接影响到残膜回收机的作业效率和回收效果。设计了残膜回收机关键部件监测系统总体方案,对机具关键部件松土齿耙不同工况下实施应变测量,入土深度、前进速度不同,对松土齿耙应变产生明显影响。动态测试试验在入土深度80 mm时,模块数据采集稳定性比较好,不同前进速度平均相对误差均在10%左右,整体平均相对误差为10.12%,测量精度可进一步提升。

新型产甲烷菌系提高极限含水油藏采收率技术

我国东部老油田已整体进入特高含水开发阶段,呈含水上升快、采油速度低、水驱效益低等开发特征,现有提高采收率技术已无法实现原油的经济采出,亟需建立接替技术。为此,以胜利油田某聚驱后油藏为试验区,开展了油藏菌群结构分析、新型产甲烷菌系的激活产气、油藏适应性及驱油性能研究,探索新型产甲烷菌系在这类油藏的应用潜力。研究结果显示,试验区油藏具有丰富的石油烃降解菌,有利于生物气化技术的实施。模拟试验区油藏条件下,新型产甲烷菌系与油藏内源微生物有较好的相容性,90 d每克原油的产气量达到3.12 mmol,是单独激活油藏微生物产气量的4.5倍,且产生的气体中甲烷气占比达到78%。菌群结构分析显示,新型产甲烷菌系占比达到35.9%,是产气速率大幅提升的关键。适应性研究结果显示,在油藏温度低于65℃、原油黏度小于1 356 mPa·s条件下,新型产甲烷菌系均展示了良好的产气性能。利用实验室设计的物理模型,评价了该菌系产气提高驱油性能,结果显示,注入该菌系后产气作用有效动用了模型顶部的剩余油,极限含水条件下驱油效率提高5.4个百分点;在此基础上提出了生物气化技术提高极限含水油藏采收率的机理。

松辽盆地深部基底地应力状态:来自松科2井地应力实测数据的证据

松辽盆地基底内的地应力状态是地震等地质灾害研究、盆地动力学分析和油气资源开发利用等领域的重要基础数据。岩心非弹性应变恢复法是近年来发展起来的基于钻孔岩心的近原位三维地应力测量方法。本文将岩心非弹性应变恢复法应用于松辽盆地大陆科学钻探松科2井(SK-2)深部地应力测量,获得了松辽盆地基底内近6~7 km的三维地应力状态,结果表明盆地基底内(6646~6846 m)为走滑断层应力环境(σ_(H)>σ_(V)>σ_(h)),最大水平主应力方向为近E-W方向。盆地基底内的应力状态与盆地内及周边邻近区域的震源机制解(震源深度7~15 km)所反演的应力环境相吻合。盆地基底处于以E-W向近水平挤压为主导的构造应力场,这种应力状态的形成,可能为西太平洋板块NW向挤压运动背景下,受控于NE-NEE走向的依兰—伊通断裂和敦化—密山断裂右行走滑产生的次级应力场。研究结果对于认识区域构造应力场背景及松辽盆地的形成与演化过程具有重要参考价值。

基于无线通讯技术的松土装置应力应变监测系统设计与试验

【目的】测量滚筒式残膜回收机中的主要部件松土齿耙在作业过程中监测系统装置的应力应变状况,为提高残膜回收机工作效率、降低松土齿耙的故障率提供参考。【方法】设计松土齿耙应力应变监测系统,通过ANSYS分析确定监测点,采用DH5922N数据分析仪标定传感器,采集模块对松土齿的微小变形进行应力应变测量,连续监测松土齿应力应变数据,并针对松土齿耙壅土过载工况下提前预警。【结果】应力应变监测系统可以有效的对松土齿耙应力应变实时监测,模拟机具田间作业工况,轻度过载阈值为140 Mpa,严重过载阈值为180 Mpa,监测结果整体平均相对误差为10.12%,过载阈值设置可提前预警。【结论】松土齿耙应力应变监测系统主要由微处理器、应力应变采集模块、AD模数转换模块、电源模块、通讯模块、云平台可视化界面6部分组成,可实时监测松土齿耙的应力应变作业状况。

高应变动测技术在如东海域大直径钢管桩基工程中的应用研究

基于江苏如东海域三根大直径敞口钢管桩的初打和复打高应变动测试验数据,提出了适用于该海域的桩端折减系数η的推荐值和承载力恢复计算公式,为该海域大直径钢管桩基础的承载力评估提供了技术依据。敞口钢管桩高应变试验数据显示,试验桩侧阻力的恢复系数都远大于端阻力的,且桩侧阻力随时间增长显著,但端阻力的增长却很小。基于此,推荐如东海域大直径敞开钢管桩的桩端阻力折减系数η取0.05进行估算。此外,通过桩基土体恢复和增长机理探讨,提出桩基承载力恢复计算公式,且验证误差在10%以内。

沥青胶结料应变延迟恢复特性的动态剪切流变试验表征

沥青胶结料在中、高温条件下的变形恢复特性直接影响沥青混合料的抗车辙性能。传统的经验指标(针入度、软化点等)以及一些基于复数模量的力学性能指标在表征沥青的应变延迟恢复特性方面存在不足。本工作基于串联Maxwell模型和并联Kelvin模型所描述的力学行为差异及粘弹性力学参数的频率响应特征,提出了采用相位角频域曲线的斜率来表征沥青胶结料应变延迟恢复特性的方法。本研究综合分析了三种不同针入度水平的基质沥青和两种SBS改性沥青在30~70℃下的复数模量和相位角参数,发现相位角频域主曲线相比复数模量主曲线可以更清晰地反映不同类型沥青胶结料的粘弹力学特性差异。试验结果表明,SBS改性沥青的相位角并非如基质沥青随角频率增加单调降低,而是会在特定的温度、频率区间呈现增长趋势。此规律可用于表征沥青胶结料的应变延迟恢复特性,并用于评价材料在特定温度范围的抗车辙性能。

孔隙压力变化对岩石强度特性的影响

在油气开采过程中,注采制度的改变必然会引起孔隙压力的波动,进而影响到储层岩石的力学性质。通过三轴抗压实验研究不同孔隙压力下的岩石强度特性及周期性孔隙压力作用下的岩石变形特征,结果表明,围压恒定,随孔隙压力下降,岩石的三轴抗压强度、弹性模量、体积模量、剪切模量都呈现增大趋势,泊松比整体呈下降趋势。对采用降压方式开发的油气藏,随着孔隙压力降低,岩石体积模量增大,体积压缩系数减小,岩石的可压缩性逐渐减弱。孔隙压力周期性加、卸载过程中岩石的轴向应变、径向应变和体积应变都将随循环周期逐渐累积,在加、卸载初期变化较大,随循环次数增加逐渐趋于稳定。岩石强度及变形规律随孔隙压力的变化规律表明,油气藏开发初期的压力降落对储层物性的影响和损害大,在储层开发前期若不采取有效措施稳定地层压力,到储层开发后期,再通过注入流体来改变地层的渗透率不会产生明显的效果,而且岩石变形的累计还可能诱发、诱导地层破坏甚至灾害性事件发生。

Fe-Mn-Si-Cr-Ni-C形状记忆合金回复应力的研究

研究了预应变量、加热和冷却工艺对FeMn－Si-Cr－Ni－C形状记忆合金回复应力的影响。结果表明，当预应变量小于3％～4％时，随应变量的增加，回复应力增加。大于3％～4％后，则下降。同一温度下，冷却过程的回复应力大于加热过程的回复应力。停止加热时的温度越高，冷却过程中的回复应力越大。

尾矿区不同植被恢复模式下高效固氮菌的筛选及Biolog鉴定

为了从铁尾矿中获得高效土著固氮菌,采用选择性无氮培养基从不同恢复模式下铁尾矿土样中筛选高效固氮菌,并且通过乙炔还原法对分离出的48株固氮菌进行固氮酶活性测定。结果表明:筛选出两株具有较高固氮活性菌株Db1与Ec1,Biolog鉴定为固氮菌属(Azotobacter),固氮比活力分别为203.20 nmol·mg-1·h-1和307.23 nmol·mg-1·h-1。不同植被恢复模式、物种多样性、尾矿坡向、工程措施、恢复年限均对尾矿固氮菌株数量有影响。样地处于尾矿阳坡,或属于人造混交林,或植被恢复年限长,又或者实施六孔砖、坡岩造地等工程措施的尾矿植被恢复模式下筛得的固氮菌菌株数较多或固氮活力较高。

微生物采油技术的研究进展及展望

经过70多年的发展,微生物采油技术(MEOR)已经成为继热力驱、化学驱、聚合物驱之后的第4种提高采收率的新的"三采"技术,并且越来越受到人们的重视。在介绍微生物采油技术发展历史的基础上,重点阐述了微生物采油的机理、菌种筛选和评价的方法以及应用该技术的油层条件和应用前景,并提出了一些建议。

热变形动态软化本构模型

动态回复、动态再结晶是奥氏体热变形过程中动态软化的主要机制。建立了动态回复、动态再结晶型流变曲线模型，５０ ％ 再结晶应变等特征应变与形变参数 Ｚ 间的关系模型以及基于 Ｅｎｇｌｅ Ｂｒｅｗ ｅｒ 理论的形变激活能模型。提出了一种应用最优化技术求解非线性本构模型的新方法。用 Ｇｌｅｅｂｌｅ２０００ 型热／力模拟试验机对 Ｓｔ４１ 钢进行了平面应变热压缩试验。实验结果及有关文献报导印证了模型的正确性。