喷丸对车轮辐板表面残余应力的影响

采用小直径盲孔法,对车轮辐板表面下残余应力分布状态进行测试和分析。通过对喷丸车轮辐板表面下残余应力分布状态和未喷丸车轮辐板表面下残余应力分布状态的对比,分析喷丸对车轮辐板表面下残余应力分布状态的影响。试验研究结果表明,喷丸处理能够有效改善车轮辐板表面残余应力状态,从而提高车轮的安全使用性能。     

钛及钛合金喷丸强化研究进展

喷丸强化能够显著提高钛及钛合金材料的常规抗疲劳性能和微动疲劳抗力,在最佳的喷丸工艺条件下可以得到较好的性能.本文从组织强化、应力强化、残余压应力及其松弛、表面粗糙度几方面叙述了钛合金的喷丸强化机制和研究进展.最后阐述了喷丸强化对钛合金力学性能的影响研究.     

喷丸处理对TiAl合金拉伸性能的影响

采用氧化锆颗粒在不同喷射压强下对成分为Ti-47.5Al-2.5V-1.0Cr(%,原子分数)的铸造TiAl合金进行喷丸处理实验,分析试样表面状态变化及其对室温拉伸性能的影响,结果表明,喷丸处理增加了表面粗糙度,改变了试样的表面形貌,使表面损伤痕迹的大小和方向均发生变化,且在试样的表面形成残余压应力,这些表面性质的改变程度均随喷射压强的提高而增大;喷丸试样的抗拉强度因表面压应力的存在而有所提高,但由于表面损伤和表面压应力的综合作用,其室温拉伸塑性在1×105Pa喷射压强下增加,而在2×105 Pa和2.5×105Pa的喷射压强下回落到原拉伸塑性水平.     

喷丸处理对S形辐板车轮辐板表面周向残余应力变化影响的试验研究

采用X射线衍射法对喷丸处理前后车轮辐板表面周向残余应力状态的实际变化情况进行了试验研究,研究结果表明,喷丸处理有效改善精加工过程对辐板表面残余应力状态的恶劣影响,从而提高车轮的安全使用性能。     

电磁强化处理对硬质合金涂层刀具组织及性能的影响研究

研究了电磁强化处理对硬质合金涂层刀具物理性能、微观组织、残余应力及切削性能的影响。结果表明,电磁强化对硬质合金磁性能及力学性能均无明显影响,却使刀具寿命提升了18.9%,相同切削时间的后刀面磨损量减小了27%。通过XRD测试刀具残余应力,结果表明电磁强化降低了刀具刃边的残余应力。通过SEM表征刀具微观组织,发现电磁强化提高了材料致密性,减少了微裂纹数量,从而可提高刀具的抗崩损能力。此外,电磁强化刀具切削表面吸附的球形纳米氧化物颗粒起到了减少摩擦、提升刀具抗磨损能力的作用。     

表面加工方法对TC4钛合金表面完整性及高周疲劳性能的影响

研究了磨削、一次喷丸、二次喷丸3种表面加工方法对TC4钛合金表面完整性及高周疲劳性能的影响规律,采用白光干涉仪、X射线残余应力测试仪对经不同方法加工的试样的表面形貌、表面粗糙度和表面残余应力分布等表面完整性参数进行了表征。采用旋转弯曲疲劳试验机分别测试了不同方法加工的光滑试样(应力集中系数Kt=1)和缺口试样(Kt=2)的旋转弯曲疲劳S-N曲线。结果表明,相比磨削,一次喷丸和二次喷丸处理后TC4钛合金光滑试样和缺口试样的疲劳极限均显著提高,TC4钛合金的疲劳缺口敏感性下降。另外,二次喷丸的疲劳极限增益效果优于一次喷丸的,原因是二次喷丸在TC4钛合金表面形成了更优的残余压应力场分布和更低的表面粗糙度。     

激光冲击喷丸对2195铝锂合金组织结构及抗应力腐蚀性能的影响

研究了激光冲击喷丸(LSP)对2195铝锂合金组织结构及抗应力腐蚀性能的影响。研究结果表明激光冲击处理后,2195铝锂合金表层晶粒细化到纳米量级,多次冲击能使表层晶粒进一步细化。残余应力测试结果表明激光冲击喷丸能够引入残余压应力,多次冲击后残余压应力数值更大。此外,应力腐蚀实验结果表明激光冲击喷丸能够有效提升2195铝锂合金的抗应力腐蚀性能。在应力腐蚀环境中,激光冲击喷丸诱生的表层残余压应力和晶粒细化层能够阻碍裂纹的萌生和扩展,防止应力腐蚀断裂。     

TC17钛合金叶片制造过程的表面完整性研究

采用多种最终加工工序组合,在TC17钛合金叶片表面引入不同表面完整性状态,研究最终加工工序对叶片表面形貌、平均粗糙度、残余应力的影响。结果表明:仅振动光饰处理后,表面平均粗糙度在0.2μm以下,表面残留有磨料运动痕迹,残余应力影响层深度约为30~40μm,表面残余应力仅-200 MPa左右;不进行振动光饰处理时,陶瓷丸喷丸比玻璃丸喷丸后叶片表面粗糙度更佳,喷丸后叶片表面Kurtosis值接近3,本研究中残余应力影响层深度约为100μm,表面残余应力在-750~-850 MPa之间;喷丸后进行振动光饰可消除叶片表面的喷丸弹坑,平均粗糙度减小到0.2μm以下,残余应力影响层深度与未经振动光饰处理的相当,表面残余应力变化小。当加工痕迹被喷丸消除时,叶片表面Kurtosis值接近3,这说明弹坑底部圆滑,因此认为Kurtosis值可作为表征喷丸表面的特征粗糙度参数。     

高强铝合金表面强化工艺研究

铝合金表面强化包括喷丸强化、振动强化和滚筒强化，它们均使材料表面产生一层强化层，其深度约在0．07～0．5mm。研究了滚筒强化处理后7804高强铝合金厚板的表面残余应力、硬化层深度和疲劳性能。试验结果表明，滚筒强化处理能明显提高7804铝合金厚板的疲劳性能。     

喷丸强化对TB6钛合金疲劳性能和表面完整性的影响

为了提高TB6钛合金零件的疲劳抗力,研究了喷丸强化对TB6钛合金疲劳性能的影响,并采用白光干涉仪、X射线应力测量仪、显微硬度计及扫描电子显微镜等仪器对其表面完整性进行分析,探讨喷丸强化机制。结果表明:相比未处理的试样,喷丸处理试样的旋转弯曲疲劳寿命显著提高。喷丸强度对TB6钛合金的疲劳性能影响显著,随着喷丸强度的增加,残余压应力层和硬化层深度相应增大,对疲劳性能有利;而同时表面粗糙度也在增大,局部应力集中效应会抑制疲劳性能的改善。     

A laboratory approach to the dynamics of psychological stress.

"This paper undertakes 2 somewhat limited tasks: (a) an analysis of some of the key problems in experimentation, and (b) the presentation of a brief account of some research from the author's own laboratory which was designed to throw light on some of the psychological mechanisms underlying stress reactions." Original research is summarized in 4 figures presenting the effect on skinconductance pattern of various conditions. The theoretical and methodological problems inherent in the field of psychological stress require attention to psychological processes (as well as the physiological) and the empirical conditions which identify these processes. "In the experimental laboratory what we need are more carefully thought out analogues of these psychological processes." (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Review of Stress reduction and prevention.

Reviews the book, Stress reduction and prevention edited by Donald Meichenbaum and Matt E. Jaremko (1983). In this edited volume, Meichenbaum and Jaremko extend the heuristic value of the stress management paradigm by having a number of researchers present their observations and programmes under the stress inoculation training umbrella. The organizational tactic is a success, as the book contains a wealth of theoretical and practical information dealing with stress management and prevention. The book is divided into three sections. The goal of the first section is to have the contributors survey the literature on stress and coping and to demonstrate the practical implications of their research. The second section of the book deals exclusively with the stress inoculation training paradigm. The third and final section represents the heart of the book. The reader is led through a number of interesting and novel applications of stress inoculation training. The editors are to be commended for this book--it is definitely worth purchasing (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Neural bases of moderation of cortisol stress responses by psychosocial resources.

Psychosocial resources have been tied to lower psychological and biological responses to stress. The present research replicated this relationship and extended it by examining how differences in dispositional reactivity of certain neural structures may underlie this relationship. Two hypotheses were examined: (a) psychosocial resources are tied to decreased sensitivity to threat and/or (b) psychosocial resources are associated with enhanced prefrontal inhibition of threat responses during threat regulation. Results indicated that participants with greater psychosocial resources exhibited significantly less cortisol reactivity following a stress task, as predicted. Analyses using functional magnetic resonance imaging revealed that psychosocial resources were associated with greater right ventrolateral prefrontal cortex and less amygdala activity during a threat regulation task but were not associated with less amygdala activity during a threat sensitivity task. Mediational analyses suggest that the relation of psychosocial resources to low cortisol reactivity was mediated by lower amygdala activity during threat regulation. Results suggest that psychosocial resources are associated with lower cortisol responses to stress by means of enhanced inhibition of threat responses during threat regulation, rather than by decreased sensitivity to threat. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

金属成型过程中摩擦的分析

本文从微观入手对金属压力成型过程中摩擦的形成原因进行了分析,认为摩擦是由于变形金属被压入工具表面的凹坑所引起的。摩擦功率等于此部分金属的变形功率,当它的变形功率大于在界面产生剪切流动的功率时,摩擦由滑动转变为粘着摩擦。同时,根据对工具表面的某些假设,推导了摩擦应力与粗糙和静水压应力等之间的关系,并求出了发生粘着摩擦所需的静水压力。计算结果表明,建立的摩擦模型是比较有效和合乎实际的,它为理论计算摩擦     

A further study of the effect of stress on palmar prints.

In a recent publication, Mowrer has described a method for obtaining palmar prints. Presumably densitometer measurements of such prints vary directly with emotional upset and relaxation. This document describes a study that was designed to test directly the hypothesis that real-life stress can be related to the index of palmar sweat. All measurements were taken during a period of stress rather than during a temporally adjacent period. Briefly, the palmar prints of a group of 34 college students were taken during an examination and contrasted with control prints of the same Ss which were taken either two weeks prior to the examination or two weeks after the examination. The method utilized for taking the palmar prints was that described by Mowrer. The results are described. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

计算机辅助齿轮试验台设计及关键零部件强度计算的软件开发与应用

系统介绍了齿轮试验的设备、测试方法以及试验方案,并对其优、缺点进行了阐述。通过比较并结合实际需求设计了合理的试验台结构,同时,对各部件的载荷工作状况进行了计算和校核。同时介绍了一种应用Delphi软件开发的计算齿轮接触应力的程序,用户可以通过输入一些设计参数来方便、快捷、准确的计算齿轮的接触应力并加以校核。     

石油套管的壁厚公差对承载能力的影响

石油套管的强度计算是按API标准进行的，它未能反映高强度套管和尺寸公差对抗压溃能力的影响。利用弹塑性力学理论建立理想的石油套管的抗压溃能力计算公式，并考虑套管的壁厚公差对计算公式进行修正。用该方法对受均匀载荷及非均匀载荷作用的套管进行分析，并同有限元计算结果相比，两者十分吻合，说明该方法的有效性。     

带钢淬火变形及硬度偏低原因浅析

针对带钢材料在淬火处理后出现的变形及硬度偏低的情况，从其生产工艺、化学成分，及金相组织方面，分析了其产生的原因，结果表明，造成此情况的原因是原材料的脱碳。     

不同应力状态下带钢的破鳞机理

利用自主设计的拉矫机对热轧带钢进行不同应力状态的破鳞试验,采用金相显微镜、扫描电镜和能谱分析对破鳞前后氧化皮的表面和界面进行分析,研究了带钢不同应力状态下的破鳞机理.试验结果表明,随着拉应力和压应力的增大,氧化皮全剥落率不断增大,并逐渐趋于稳定,且压应力的破鳞效果强于拉应力;拉应力作用下氧化皮以分层剥落为主,外层Fe3O4发生剥落,内层FeO仅在缺陷处发生少量剥落;而压应力作用下氧化皮以全剥落为主,临界弯曲应力随剥落量的增大而增大.     

厚壁冷成型钢构件残余应力分析

从理论上将厚壁冷弯残余应力形成过程模拟成大变形加载(弯曲)和弹性卸载(回弹)过程,对不同厚度、不同相对弯曲半径下的冷成型厚钢板进行了大变形弯曲和回弹分析,得到了弯曲应力场和回弹应力场,将这两种应力场相叠加,得到了残余应力场,并分析了其分布规律,最后以国外的实测结果为基础进行了比较分析,证实了该理论分析方法的正确性,从而为进一步研究残余应力对厚壁冷成型钢构件性能的影响奠定了理论基础。