考虑端部摩擦的中心直裂纹巴西圆盘断裂参数解析解

运用权函数法推导出考虑加载端摩擦的四种形式分布载荷加载下,中心直裂纹巴西圆盘试样在任意I/II复合型断裂模式下I、II型应力强度因子及T应力的解析解,并探究了端部摩擦及载荷分布角度对断裂参数的影响。研究结果表明:（1）当中心裂纹相对长度β较小时,纯I型、纯II型断裂的Y_I、Y_II及T*（分别是量纲为一的I型、II型应力强度因子及T应力）均随摩擦系数及载荷分布角度增大而减小;但是,当β较大时,摩擦系数增大可使纯I型Y_I增大,而载荷分布角度增大可使纯II型T*增大。（2）接触载荷分布形式为常数函数时,载荷分布角度对断裂参数的影响最显著,而四次函数下其对断裂参数的影响相对最小。（3）当β较小时,纯II型加载角度随载荷分布角度增大而减小;当β较大时,其随载荷分布角度增大而增大;摩擦系数增大可使纯II型加载角度增大。      

断层转折及其断层组合应力特征控油规律研究

受地震资料多解性和分辨率局限性的影响,依靠地震反射解释地下断层信息并不全面。鉴于此,对断裂转折和折射机理以及不同断裂组合型式应力集中状态做了系统研究。综合研究表明:断裂转折扩容控油,断裂转折处在剪切力作用下会形成规模性引张扩容空间,其与高孔高渗砂体的有利配置控制油气的主流向和富集程度;断裂切割深度突变的部位控油,断裂切割深度突变的位置是应力集中部位,一般也是断层面叠置的部位,张性裂缝通常发育,主断裂与其诱导的张性裂缝贯通联接构成油气优势运移通道和增大运移量;强应变区控油,油气往往富集于断裂脆塑性接触带或接触面构造应力叠复的强应变区,且油气富集强度与断裂面变形强度一般呈正相关。     

无底柱分段崩落采矿法回采方式对进路应力影响的模拟分析

以夏甸金矿无底柱分段崩落采矿法回采方式调整为工程背景,运用FLAC3D数值模拟分析软件,从应力变化规律、塑性破坏区变化特点和位移场分布特征等多个方面,对不同回采方式的采场地压变化规律进行数值模拟对比研究。研究发现无底柱分段崩落采矿法在回采过程中垂直应力集中区域出现在回采进路两帮的岩体中,水平应力集中区域出现在回采进路的顶底板中。当采用双翼阶梯式回采时,回采进路中应力分布较为均匀,总体应力较小,是最为合适的采矿方法。     

基于CAE技术的热连轧机齿轮减速箱输入轴断裂分析

某钢企热连轧生产线精轧机组在轧制过程中减速机输入轴发生多次断裂事故,对此利用有限元分析软件对该减速机齿轮轴进行了CAE分析,得到了该齿轮轴的应力分布情况。得出齿轮轴两端的R3圆角太小,这些部位产生较大的应力集中是造成齿轮轴断裂的主要原因。根据分析得到的结果,针对该齿轮轴结构提出了相应的改进的措施,并对改进后的齿轮轴重新进行CAE分析。改进后应力集中部位的最大应力值相比较改进前减小了36.8%,应力集中现象得到很大程度的改善,证明了改进措施的合理性和可行性。     

Al2O3-40%TiO2陶瓷涂层残余应力的有限元分析

为分析大气等离子喷涂Al2O3-40%Ti O2复合陶瓷涂层在冷却过程中涂层崩裂的现象,本文采用有限元方法,研究了涂层内部残余应力分布情况,探讨了涂层厚度、孔隙、裂纹等因素对残余应力的影响。结果表明:基体与粘结层和粘结层与涂层的界面边缘处出现了应力集中区域,随着X尺寸(模型水平方向的距离)的增加,涂层及粘结层内部应力由压应力转变为拉应力;涂层厚度只对残余应力值有影响,对应力分布状态影响较小,随着涂层厚度的增加,X向(径向)应力逐渐增加,Y向(轴向)应力及剪切应力在界面边缘处急剧变化;大孔隙、纵向裂纹对涂层残余应力影响较大。有限元模拟分析较好的解释了涂层在冷却过程中涂层层状崩裂的现象。     

陕西李家沟金矿床的控矿条件

近东西弧形压扭性断裂F2 为主干断裂 ,是矿床的控矿构造 ,并严格控制着矿体的分布 ,在入字型排列的构造相交部位为矿液上涌的良好通道和容矿场所 .探讨了控矿构造形迹的力学性质及相互关系 ,成矿控制因素以及围岩蚀变与成矿的关系     

山东招远界河金矿床断裂构造特征及其控矿规律

界河金矿床为胶东地区典型的蚀变岩型金矿床,矿床产于望儿山断裂的北段,矿体的产出严格受断裂构造控制。矿区断裂构造主要由F1、F2主断裂及一系列坎级断裂组成,矿体主要受F1主断裂控制。主断裂沿走向及倾向均呈现波状起伏的特征,其在主成矿期具有左型走滑的正断层性质。主断裂面凸凹转换部位对成矿最有利,其控制了矿体沿走向呈似等距性分布以及向南西侧伏的规律。次级断裂的类型以及构造岩的类型和破碎程度控制了不同的矿化类型。次级节理裂隙发育的频度控制着裂隙脉型矿化的强弱,形成了在主断裂与次级断裂收敛部位富集成矿的“断夹片式”控矿构造模式。通过断裂构造控矿规律分析推断,在I号矿体深部存在一定的找矿前景。     

基于复杂洞穴模型的阵列侧向测井正演响应研究

碳酸盐岩、火成岩等复杂油气藏是油气勘探的重要目标,洞穴型储层作为其重要的储集空间类型,洞穴的识别和预测相当重要。利用三维有限元数值模拟方法研究了洞穴内流体电阻率,洞穴中心与仪器中心的纵向距离,洞穴的扁平程度,钻穿程度和椭球形洞穴长轴与井轴夹角的变化的仪器响应特征,以及对洞穴型储层的定性识别和定量计算提供理论基础。研究表明:仪器响应随着洞穴内流体电阻率增大而增大;仪器响应随着仪器中心与洞穴中心的纵向距离的减小而减小,越接近洞穴中心受到洞穴的影响越大;随着洞穴的扁平性增大,仪器响应的变化程度也越大,对洞穴的识别能力减弱;随着椭球形洞穴钻穿程度的增大,仪器对洞穴的识别能力也增强,钻穿程度在20%以下,对阵列侧向测井仪器响应影响程度较大;仪器中心轴与椭球形洞穴长轴夹角在10(°)～60(°)之间时对仪器响应的影响较大,且随夹角的增大仪器响应也增大。     

陕西李家沟金矿床的控矿条件

近东西弧形压扭性断裂F2为主干断裂，是矿床的控矿构造，并严格控制着矿体的分布，在入字型排列的构造相交部位为矿液上涌的良好通道和容矿场所，探讨了控矿构造形迹的力学性质及相互关系，成矿控制因素以及围岩蚀变与成矿的关系。     

25MnSi、20MnSi螺纹钢筋冷弯外侧横裂的研究

本文分析了螺纹铜在横筋顺轧制方向一侧根部冷弯横裂的各种可能原因,最后得出结论:对20MnSi、25MnSi螺纹钢筋,其横裂产生的根本原因是两种应力的叠加超过了材料本身的强度。第一种应力集中来自横筋改变了正常的应力分布而造成其两侧根部应力线密度高于其它部位。第二种应力集中是仅仅存在于横筋顺轧制方向一侧根部因流线断裂造成的应力集中。文章分析了两种应力集中的成因并提出了缓解办法,基本上消除了螺纹钢的弯曲横裂。     

Influence of membrane oxygenators on the pulsatile flow in extracorporeal circuits: an experimental analysis

The vertical force applied to an endodontic spreader generates stress along the canal walls. Recognizing the potential for this stress may reduce the incidence of vertical root fractures. A photoelastic acrylic model was fabricated to exhibit the stress produced during obturation of curved canals using the lateral condensation technique. Twenty standardized models simulating curved canals (32 degrees) were formed within PL-2 photoelastic acrylic resin blocks. The canals were fitted with a gutta-percha point, and either a stainless-steel or nickel-titanium finger spreader was inserted. An Instron 4502 universal testing machine applied a vertical force of 20 Newtons to the spreader. Quarter wave and polarizing filters were used with backlighting to generate the fringe patterns in the models. Photographs of the resulting stress lines showed that the stainless-steel spreaders created three areas of concentrated stress. The nickel-titanium spreaders induced stress patterns spread out along the surface of the canals, thus reducing the concentration of stress and the potential for vertical root fracture.     

Influence of Profile of Blast Furnace on Motion and Stress of Burden by 3D-DEM

 The objective of the present investigation is to analyze the influence of profile of blast furnace on the burden motion and stress field through 3D-DEM (three-dimensional discrete element method). It is clarified that the decrease of shaft angle speeds up the velocity of burden descending and decreases normal stress between particles or particle and wall. This change is good for the smooth operation of blast furnace. However, ore and coke would be mixed for the too small shaft angle (75°), which would influence the permeability in blast furnace. Thus, the appropriate shaft angle is around 80°. Decrease of bosh angle prevents the burden descending motion and increases normal stress between particles and bosh wall. Meanwhile, maximum normal stress acting on the wall moves from belly wall to bosh wall in the case of 68° bosh angle, which accelerates abrasion of refractory in bosh by friction force between particles and wall. Although burden descends smoothly in the case of 88° bosh angle, room is not enough for the ascending heated gas flow. Thus, the appropriate bosh angle is about 78°.     

The effect of subacute administration of a neem pesticide on rat metabolic enzymes

Dual search coils were used to record horizontal, vertical and torsional eye movement components of one eye during nystagmus caused by off-center yaw rotation (yaw centrifugation). Both normal healthy human subjects (n=7) and patients with only one functioning labyrinth (n=12) were studied in order to clarify how the concomitant linear acceleration affected the nystagmus response. Each subject was seated with head erect on the arm of a fixed-chair human centrifuge, 1 m away from the center of the rotation, and positioned to be facing along a radius; either towards (facing-in) or away from (facing-out) the center of rotation. Both yaw right and yaw left angular accelerations of 10 degrees s(-2) from 0 to 200 degrees/s were studied. During rotation a centripetal linear acceleration (increasing from 0 to 1.24xg units) was directed along the subject's naso-occipital axis resulting in a shift of the resultant angle of the gravitoinertial acceleration (GIA) of 51 degrees in the subject's pitch plane and an increase in the total GIA magnitude from 1.0 to 1.59xg. In normal subjects during the angular acceleration off-center there were, in addition to the horizontal eye velocity components, torsional and vertical eye velocities present. The magnitude of these additional components, although small, was larger than observed during similar experiments with on-center angular acceleration (Haslwanter et al. 1996), and the change in these components is attributed to the additional effect of the linear acceleration stimulation. In the pitch plane the average size of the shift of the axis of eye velocity (AEV) during the acceleration was about 8 degrees for a 51 degrees shift of the GIA (around 16% of the GIA shift) so that the AEV-GIA alignment was inadequate. There was a very marked difference in the size of the AEV shift depending on whether the person was facing-in [AEV shift forward (i.e. non-compensatory) of about 4 degrees] or facing-out [AEV shift forward (i.e. compensatory) of around 12 degrees]. The linear acceleration decreased the time constant of decay of the horizontal component of the post-rotatory nystagmus: from an average of 24.8 degrees/s facing-in to an average of 11.3 degrees/s facing-out. The linear acceleration dumps torsional eye velocity in an manner analogous to, but independent of, the dumping of horizontal eye velocity. Patients with UVD had dramatically reduced torsional eye velocities for both facing-in and facing-out headings, and there was little if any shift of the AEV in UVD patients. The relatively small effects of linear acceleration on human canal-induced nystagmus found here confirms other recent studies in humans (Fetter et al. 1996) in contrast to evidence from monkeys and emphasizes the large and important differences between humans and monkeys in otolith-canal interaction. Our results confirm the vestibular control of the axis of eye velocity of humans is essentially head-referenced whereas in monkeys that control is essentially space-referenced.     

45号钢延迟断坯事故分析与研究

结合生产实际,对断坯试样进行了光谱、低倍、扫描电镜(SEM)及能谱分析,分析认为：板坯内部裂纹是45#钢板坯横向脆断的根本内因,热坯缓冷速度过快造成板坯内部存在较大收缩应力或吊运过程中受到较大的机械外力是板坯横向脆断主要外因;同时,二次冷却不均匀影响柱状晶生长并造成元素偏析、疏松及夹杂物富集,是造成板坯内部裂纹的主要原因。     

Evaluation of pulmonary arterial trunk on frontal chest radiograph in patients with atrial septal defects

Atrial septal defect (ASD) is one of the most common congenital cardiac anomalies encountered in adulthood. The evaluation of the pulmonary hypertension in ASD is clinically important for operative indication and prognosis. The pulmonary vasculature in chest radiographs in patients with ASD is characterized as dilatation of the central pulmonary arteries and increase of the peripheral pulmonary vessels in patients without pulmonary arterial hypertension (PH) and constriction of the peripheral pulmonary arteries in those with pulmonary hypertension. While the dilatation of the main pulmonary artery occurs in the patients both with and without pulmonary hypertension, its precise radiographic evaluation with regard to the morphological and hemodynamic change of the right ventricle and pulmonary arteries has not been reported. This study was to determine if the contour of the main pulmonary artery segment of the cardiac silhouette in the conventional frontal chest radiograph could be used 1) as indicators of PH or raised right ventricular pressure and 2) as a reliable base for evaluation of the size of the right ventricule (RV) in ASD. The intersection of the line (line A) drawn tangentially to the lateral lower margin of the main pulmonary artery segment to the horizontal line at the left hemidiaphragm is closely related to the apex of RV as measured by right ventricular angiography in supine position. The ratios of the distance of the intersection from the midline of the frontal chest radiograph to the internal diameter of the left hemithorax in normal subjects were 0.50 +/- 0.08 (mean +/- standard deviation) for male and 0.54 +/- 0.09 for female. The ratio increased with increasing left-to-right shunt [0.59(Qp/QS < 2), and 0.71 (Qp/QS > 2)] and shows a tendency of decrease with raised right ventricular systolic pressure (0.52-0.64 in normal subjects and patients with mild raised right ventricular systolic pressure and 0.43 in patients with severe raised right ventricular systolic pressure). The measurement of the angle of the line A from the vertical line tends to show increasing decrease with raised pulmonary arterial and right ventricular systolic pressure (20.1 degrees +/- 4.9 in mild PH and 10.3 degrees +/- 4.1 in moderate to severe PH). The decrease of the angle of the line A to the vertical line was well correlated with conventional radiographic criteria of the right and left central pulmonary arteries of PH.(ABSTRACT TRUNCATED AT 400 WORDS)     

Treatment of spondylolysis and spondylolisthesis in children and adolescents

The treatment of spondylolysis and spondylolisthesis in children depends on the severity of clinical symptoms, pathologic anatomy, and prognosis. Simple spondylolysis can be cured by immobilization alone in selected cases, or by surgery when it remains symptomatic and resistant to nonoperative treatment. The majority of cases are asymptomatic and require no treatment. Spondylolisthesis is classified into 2 types based on the magnitude of the lumbosacral angle: spondylolisthesis with a horizontal sacrum (lumbosacral angle > or = 100 degrees), which seldom requires surgical treatment, usually responds to orthotic management, and generally shows little progression; spondylolisthesis with a vertical sacrum (lumbosacral angle < 100 degrees) which is always progressive, can produce neurologic impairment and cosmetic and functional disability, and requires surgical treatment. In 17 cases the author has reduced the latter deformity by gradual traction in hyperextension followed by cast immobilization, then stabilized the reduction by posterolateral fusion performed through the cast without instrumentation and without opening the spinal canal. When the lumbosacral angle is not improved to 100 degrees or more by hyperextension and traction, an anterior console interbody fusion is added before the posterolateral fusion.     

Jet penetration and liquid splash in submerged gas injection

Jet penetration, bubble dispersion, and liquid splash were studied in the nitrogen-water system. Among the effects evaluated were those due to lance design, nozzle dimensions, gas driving pressure, and liquid density. In side-nozzle injection, penetration is found to increase with jet force number,N, given by the product of the gas driving pressure and the nozzle diameter. In top-submerged injection, horizontal and vertical penetrations increase with the horizontal and vertical components, respectively, of the jet force number. Liquid splash is greater in the side-nozzle injection than in top-submerged multiple-orifice injection, and appears to decrease as the number of orifices increases.     

Active Earth Pressure on Retaining Wall for c-? Soil Backfill under Seismic Loading Condition

This technical note describes the derivation of an analytical expression for the total active force on the retaining wall for c-? soil backfill considering both the horizontal and vertical seismic coefficients. The results based on this expression are compared with those obtained from earlier analytical expressions for the active force for c-? soil backfill under seismic conditions, and found to have a similar trend of variation. The parametric study shows that the inclination of the critical failure plane with the horizontal plane decreases with the increase in values of seismic coefficients; the decrease being more for their higher values. The total active force increases with the increase in value of horizontal seismic coefficient; while it decreases with the increase in value of vertical seismic coefficient except for a very high value of horizontal seismic coefficient. Design charts are presented for various combinations of horizontal and vertical seismic coefficients (kh and kv), and values of cohesion and angle of shearing resistance for estimating the total active force on the retaining wall for c-? soil backfill for practical applications.     

招远金华山金矿区成矿构造分析及找矿方向研究

通过对井下现场调查、构造编图和成矿期构造应力场的数值模拟等方面的成果综合分析,提出金华山金矿区控矿构造型式为前孙家—洼孙家主断裂及其平行次级断裂所夹的雁行张裂带。矿区构造控矿规律表现为:构造与矿化具有垂向上的分层性,构造张开中心与矿化富集中心具有一致性、成矿构造方位具有近南北向和北北东向的优选性、矿体总体产状的南东倾和南西侧伏的规律以及脉岩具有明显的控矿作用等。在此基础上对本区下一步的找矿提出了明确的方向。     

复杂地质条件下矿区初始地应力场反演分析

初始地应力场是地下工程设计和稳定性分析的重要依据.前常铁矿矿区地质构造复杂、巷道围岩破坏严重,掌握矿区地应力场的分布规律对了解巷道破坏、进行支护设计具有重要意义.采用三维有限差分数值计算软件(Flac3D),建立了考虑矿区主要断层、岩层等的三维数值模型,进行矿区地应力场的模拟,分析了矿区整体、地质构造处和-480 m中...