内燃机车曲轴中频淬火过程的数值模拟

借助 ANSYS大型有限元分析软件 ,实现了 16 V2 4 0曲轴淬火过程的计算机模拟 ,模拟结果可直观地显示出任一时刻曲轴表面及内部的温度分布、冷却曲线以及淬火结束后的残余应力分布 ,并能预测淬硬层深度。同时对比了轴颈内圆角处进行淬火和不进行淬火两种工艺的效果 ,为现场提供了用虚拟现实方法详尽分析和研究淬火工艺的工具。     

深层搅拌桩复合地基的现场试验研究

结合雍六高速公路长江二桥江北接线工程 ,对填土荷载下复合地基的应力、变形特性进行了长期现场观测研究 .结果表明 :路基经深搅桩加固后 ,沉降变形得到有效控制 .加固区沉降量较小 ,下卧层沉降量较大 ,总沉降量满足设计及规范的要求 ;柔性路堤下桩与桩间土的沉降规律有差别 ,桩身上部桩周土沉降较大 ,随着深度增加 ,桩周土沉降逐渐小于桩的沉降 ,在这个过程中 ,桩与桩周土存在等沉面 ;在填土加荷过程中 ,桩与土各自分担的应力处在动态的变化之中 :加荷时 ,桩上应力相对集中 ;间歇期 ,桩土应力比减小 ;体现了荷载传递过程中桩与土是相互协调作用的     

浅谈中承式钢管拱肋单拱桥的施工方法

右江平圩大桥钢管拱肋的制作、拼装、吊装、混凝土灌注的施工方法及注意事项 ,事故原因分析及处理。     

全20CrMnTi表面激光重熔的组织与性能研究

本文对激光重熔20CrMnTi材料表明改性层显微组织分布特征、表面硬度分布规律以及残余应力状态作了研究,结果表明,表面改性层由熔融层、相变硬化层及过渡层组成,且材料表面显微硬度得到大幅度提高,表面硬度达到HV841,约提高4倍。硬化层深度约1mm。残余应力测试得出最大残余应力出现在熔凝带中心,表现为压应力。随着离中心距离的增大,残余应力逐步降低,到熔化带边缘,表现为低幅值压应力;而熔池的外边缘应力在热影响区则转变为拉应力状态。     

关于瞬态应力强度因子和裂纹扩展加速度之间的关系探讨

将动态焦散线法与高速摄影技术相结合,本文记录了高分子材料悬臂梁内裂纹扩展加速、减速过程。一方面,利用动态焦散线可确定扩展裂尖的瞬态应力强度因子;另一方面,利用最小二乘法将裂纹扩展的水平、垂直位移分量拟合成时间(t)的四次多项式,描述了裂纹扩展方向、裂纹扩展加速度以及裂纹扩展加速度与动态应力强度因子的关系。结果表明:裂纹扩展加速度与动态应力强度因子之间存在一定的依赖关系;利用最小二乘法将裂纹扩展的水平、垂直分量拟合成时间(t)的四次多项式,可以对裂纹的扩展方向、加速度进行定量分析。     

Predicting posttraumatic growth in breast cancer survivors.

Wide variability exists with respect to how breast cancer survivors respond to common psychological and psychosocial challenges of their disease, ranging from posttraumatic stress disorder to posttraumatic growth. This cross-sectional study examined contextual, disease-related, and intraindividual predictors of posttraumatic growth in 224 randomly selected breast cancer survivors. A series of hierarchical regression analyses found that age at diagnosis, marital status, employment, education, perceived intensity of disease, and active coping accounted for 34%, 35%, and 28% of the variance in growth in relationships with others, new possibilities, and appreciation for life. These findings suggest that a more comprehensive model of growth will be helpful in understanding the various factors that play a role in breast cancer survivors' perception of psychological and psychosocial growth. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Experimental validation of FE predicted fracture behaviour in thermally sprayed coatings

The fracture behaviour of a brittle coating on a substrate is not only governed by its intrinsic fracture strength, but also by a range of other parameters. In order to be able to understand (and thus predict) the fracture response, it is very important to accurately determine the key coating properties such as elastic modulus, residual stresses and fracture strength. In the present work, the fracture behaviour of three different high velocity oxy-fuel (HVOF) sprayed WC–17% Co coatings on Ti–6Al–4V substrates was studied using four-point bending with the acoustic emission technique. The key coating properties were determined experimentally and finite element (FE) models incorporating these experimentally measured properties were used to predict the cracking behaviour. It was found that the FE model was able to predict the differences in the fracture responses of the three coating types based upon differences in their mechanical properties, which in turn enabled the properties which dominate the fracture response to be identified. Moreover, the ability to predict the fracture behaviour of the coatings provided validation of the physical basis of the FE model.     

Treatment of Posttraumatic Stress Disorder in Military and Veteran Populations.

While concerns about the psychological effects of war are not new, only recently has systematic attention been paid to such problems among past and present military personnel. There is increasing recognition that mental health has serious implications for operational performance, retention, and compensation. Although little controlled research exists with this population, preliminary evidence suggests that psychological treatments for posttraumatic stress disorder may be beneficial, albeit less so than for civilian populations. This article reviews evidence for each of several psychological treatment stages: stabilization and engagement, psychoeducation, symptom management, prolonged exposure, cognitive restructuring, and relapse prevention, with particular reference to the clinical issues raised by military personnel. Possible explanations for reduced treatment effects in this population compared with civilians are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

应用地应力模拟技术研究断块区剩余油分布

应力场数值模拟不仅能够重塑出不同阶段地应力场，而且还可以定量一半定量地预测破裂的发生、裂缝的方向和密度，进一步探讨时间和空间上油气运移的规律，为油田勘探、开发提供必要的依据。本文以大庆萨北开发区北二西断层区为研究对象，通过应力场数值模拟研究了流体运移势场与剩余油分布的关系、流体运移与构造应力的关系、裂缝形成与剩余油分布的关系，确定了剩余油分布的有利区域，为油田注采系统的设计、部署和油田开发及措施调整提供了依据。