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1.
用盲孔释放法测残余应力的基本理论导出在任意钻孔偏心下应变释放系数 A、B 的精确公式.同时通过用偏心公式和不偏心公式计算得到的残余应力值的比较,说明钻孔偏心量对残余应力值影响很大.  相似文献   

2.
杨伯源 《实验力学》1990,5(3):329-335
用钻孔应变释放法测残余应力的基本理论导出在任意钻孔偏心下应变释放系数[A],[B]的精确公式.揭示了各传统近似方法(丝栅中心应变法、纵向线积分平均应变法及有效面积上积分平均应变法)的应变释放系数随r_м/а的变化规律。并采用数值逼近法求解了钻孔偏心时的应变释放系数及残余应力.结果表明,偏心对残余应力影响很大。  相似文献   

3.
无损电测解析法测定焊接容器的残余应力   总被引:2,自引:1,他引:1  
张亦良  程咏梅 《实验力学》1994,9(4):367-375
本文从塑性增量理论出发,论述了无损电测解析法的基本原理和应用此法确定残余应力的基本步骤,并将其应用大型球罐的现场测量。其特点是在容器例行的水压试验中只需应用电阻应变片测量应变即可确定残余应力用此法所得结果同盲孔法所得结果进行了对比。表明具有一定的工程精度。  相似文献   

4.
本文用激光散斑剪切干涉法及钻孔释放法直接测取释放应变,进而计算残余应力.用模拟铝合金试件测取残余应力,条纹清晰,试验结果与理论解一致性较好。  相似文献   

5.
残余应力测定的围箍压痕法模拟   总被引:1,自引:0,他引:1  
本文从同工量测方法得到启发,提出了一种新型的残余应力测试方法-围箍压痕法。采用轴对称弹塑性有限元计算模拟了围箍压痕法测量结构残余应力的力学过程,得到了围箍压痕时不同残余应力程度下材料的变形,塑性区和接触应力分布。  相似文献   

6.
冯传玉  Bruce  S.-J.  Kang 《实验力学》2007,22(4):314-322
球形压痕技术在材料力学属性,诸如硬度,弹性模量等的测量中得到了广泛的应用.应用Twyman-Green及云纹干涉法并配合相移技术,本文对IN783合金进行了一系列的球形压痕实验研究,并对残余压痕的面内(u, v)及离面(w)变形场进行了定量测量和分析.应用面内变形测量结果,进一步对试件表面的应力-应变分布进行了分析和计算,并在离面变形场的基础上,确立了压痕周围的弹塑性边界,从而进一步应用面内的分析结果,得到材料的屈服强度.应用压痕实验的接触半径和压力并配合Tabor经验公式,本文进一步得到了材料的应力应变曲线.实验结果与已知的IN783合金相吻合.对所涉及的一系列压痕实验,本文也进行了二维有限元分析并得到了比较一致的结果.  相似文献   

7.
双向载荷作用下试件应力分布的理论和实验分析   总被引:1,自引:0,他引:1  
谢大吉  冯升波 《实验力学》1997,12(1):139-144
本文利用弹性理论对十字形试验板的应力分布进行了推导,并得出一个近似计算公式,结合电测实验进行校核,为直观起见,用有限元画出了该模型的应力等值线,证明该计算公式基本正确  相似文献   

8.
本文结合聚焦离子束-电子束(Focused ion beam-electron beam,简称FIB-EB)双束系统和真空镀膜工艺,进行微区散斑的制备工艺研究,并将所发展的微散斑制备工艺应用于喷丸镍基合金材料表面制斑,进而结合切槽法进行残余应力高温释放规律的测量研究。在FIB-EB双束系统下记录切槽前后制斑微区的图像,利用数字图像相关法计算切槽后的位移,结合InglisMuskhelishvili理论公式可计算得到残余应力。文中研究了不同温度及保温时间对残余应力释放的影响规律。结果表明,残余应力随保温时间的增长释放速度逐渐减小,最后残余应力趋于稳定值。同时,温度越高,残余应力释放越彻底,800℃下近乎完全释放。该工艺具有适用性好,效率高等优点,可望在材料微区变形测量中得到进一步应用。  相似文献   

9.
大错位量散斑干涉法测量残余应力   总被引:1,自引:0,他引:1  
乌时毅  秦玉文 《实验力学》1993,8(2):125-131
本文提出大错位量激光散斑干涉法结合钻孔法测量残余应力,对单向拉伸残余应力进行了测量,试验结果与理论解非常吻合,并且实现了对真实构件表面残余应力的测量.  相似文献   

10.
球形压痕技术在材料力学属性,诸如硬度,弹性模量等的测量中得到了广泛的应用。应用Twyman-Green及云纹干涉法并配合相移技术,本文对IN783合金进行了一系列的球形压痕实验研究,并对残余压痕的面内(u, v)及离面( w)变形场进行了定量测量和分析。应用面内变形测量结果,进一步对试件表面的应力-应变分布进行了分析和计算,并在离面变形场的基础上,确立了压痕周围的弹塑性边界,从而进一步应用面内的分析结果,得到材料的屈服强度。应用压痕实验的接触半径和压力并配合Tabor经验公式,本文进一步得到了材料的应力应变曲线。实验结果与已知的IN783合金相吻合。对所涉及的一系列压痕实验,本文也进行了二维有限元分析并得到了比较一致的结果。  相似文献   

11.
恶劣环境中应变测量的国内外发展综述   总被引:1,自引:0,他引:1  
机器部件、构件和微电子元件,很多是在恶劣环境(包括高温、高压、低温、磁场、辐射、等离子体、腐蚀环境、高速旋转、液下等)中工作的。它们的力学破坏,对人们的安全和生产有非常不利的影响。为防止这些破坏,需要通过分析、实验和计算来改进设计、制造和检测,以提供减少破坏所必要的数据。实验力学,特别是在恶劣环境中进行力学测量,在此起了关键的作用。它提供了基本数据和检测手段,用于计算和建立破坏理论模型。本文介绍在恶劣环境中,主要在高温中,进行应变测量的国内外一些发展情况。  相似文献   

12.
应变片技术在动态力学测量中的应用   总被引:11,自引:2,他引:11  
本文详细讨论了应变片技术,特别是半导体应变片技术在动态力学测量中的若干技术问题,主要有应变片及起动态应变仪的频率响应问题,应变片灵敏系数的动态标定问题。文章指出,随着数据处理微机化的日益普及,半导体材料所存在的非线性特性及拉压不对称性将不再影响到半导体应变片技术的推广使用。相反地,灵敏系数极高这一优良特性将使该项技术获得日益广泛的应用。  相似文献   

13.
This paper presents the results of an investigation evaluating the forces present in a statically loaded bicycle chain prior to and beyond sprocket engagement. Comparisons are made with previous investigations that have been limited to industrial chains and sprockets. The chain drive system for a bicycle differs from the industrial standard types not only in its size but in its operation. A high degree of lateral flexibility is required in the bicycle chain for it to operate with noncoplanar sprockets having an effective misalignment of 3 deg or more. The experimental analysis in this paper considers chain loads for a range of sprocket sizes and angles of misalignment. Results indicate that localized bending arising from misalignment between chain and sprocket can increase or decrease the strain on the side plates by a substantial fraction of the direct strain due to chain tension. The work presented here is part of a more general study of bicycle chain efficiency for competition applications.  相似文献   

14.
本文采用大子样、小子样抽样理论的数理统计方法,评定电阻应变计灵敏系数的精度等级。  相似文献   

15.
New development of the magnetic method for residual stress testing   总被引:2,自引:0,他引:2  
Experiments on specimens of mild steel and cast iron have been performed under various loading conditions. A modified formula is pur forward to analyze the cruciform specimen which is often used in magnetic methods for calibration. We assume that the relationship between the magnetic output and strain is linear and a new four-coefficient method is deduced. Finally, the results of practical applications are given.  相似文献   

16.
Experimental analysis of propagation of fatigue crack on gears   总被引:1,自引:0,他引:1  
Gears of different sizes and with different systems of loading are indispensable components of machines and devices. When optimizing such gear assemblies, on of the most important parameters is their required service life. To calculate the service life as precisely and reliably as possible, researchers need to use the required mathematical models for describing loading, the geometry, properties of materials and fracture mechanics parameters. The accuracy and reliability of the gear model assemblies can be compared only with appropriate experimental results. To this end, the authors have used and developed a series of methods and test pieces. A comparison of results has shown that the models and approaches are adequate.  相似文献   

17.
杨韶明  李树欣 《实验力学》1998,13(3):388-392
本文利用Wiliams应力函数导出的应变场渐进表达式和电阻应变片测量技术,测量张开型(I型)裂纹尖端附近两点应变来确定应力强度因子KI。通过对不同裂纹体的测试结果表明,该技术具有较好的适用性。  相似文献   

18.
郭朴仲 《实验力学》1989,4(3):261-265
本文介绍用脆漆法和电测法测定和分析车身骨架强度的方法及结果、并讨论使用这两种方法相辅相成的关系。  相似文献   

19.
In this paper, a two-dimensional (2-D) Langrangian technique for flow field measurement under high dynamic pressure is presented, which included a set of experimental device and 2-D Lagrange composite manganin-constantan ring gages. With this kind of gage, the histories of pressure and radial displacement can be measured simultaneously at different Lagrange positions in an axisymmetric shock loading flow field. The technique has some advantages over the 1-D one, such as, simplified loading device, continuously adjustable output pressure, no restriction on sample length and the availability for the study of lateral rarefaction in shock propogation. As a preliminary application, the processes of 2-D shock initiation and attenuation in compacted TNT are measured.  相似文献   

20.
This paper describes the application of the traditional four-point bending technique to conduct strain gage performance tests at moderate temperatures. The tests measure the apparent strain, linearity, drift, creep and hysteresis behavior to ascertain the reliability of strain gages to be used in the testing of experimental cylindrical vessels subjected to thermal loading. The four-point bending rig was designed to take advantage of the advances in personal computer datalogging and graphical processing software. The test rig is designed to provide a thermal barrier to minimize the heat losses and thermal isolation of the test beam while maintaining structural continuity. A low wattage and lightweight electric foil heater incorporating a precise temperature controller minimizes weight and enhances temperature stability. Gage performance data on five candidate strain gages at temperatures ranging from ambient to 215°C (419°F) are presented, and the evaluation procedure is outlined. The strain gage with the most acceptable performance was identified within the validity limits from ambient to a temperature of 215°C and from zero to a maximum strain of 1000 .  相似文献   

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