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Characterization of mechanical properties of aluminum cast alloy at elevated temperature 被引量:6
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作者 Shuiqiang ZHANG Yichi ZHANG +5 位作者 Ming CHEN Yanjun WANG Quan CUI Rong WU D.AROLA Dongsheng ZHANG 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI CSCD 2018年第7期967-980,共14页
The tensile response, the low cycle fatigue (LCF) resistance, and the creep behavior of an aluminum (A1) cast alloy are studied at ambient and elevated temperatures. A non-contact real-time optical extensometer ba... The tensile response, the low cycle fatigue (LCF) resistance, and the creep behavior of an aluminum (A1) cast alloy are studied at ambient and elevated temperatures. A non-contact real-time optical extensometer based on the digital image correlation (DIC) is developed to achieve strain measurements without damage to the specimen. The optical extensometer is validated and used to monitor dynamic strains during the mechanical experiments. Results show that Young's modulus of the cast alloy decreases with the increasing temperature, and the percentage elongation to fracture at 100 ℃ is the lowest over the temperature range evaluated from 25 ℃ to 300 ℃. In the LCF test, the fatigue strength coefficient decreases, whereas the fatigue strength exponent increases with the rising temperature. The fatigue ductility at 100 ℃. As expected, the resistance to and changes from 200 ℃ to 300 ℃. coefficient and exponent reach maximum values creep decreases with the increasing temperature 展开更多
关键词 mechanical behavior aluminum(A1)cast alloy elevated temperature digital image correlation(DIC) optical extensometer
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An in situ monitoring campaign of a hard rock pillar at great depth within a Canadian mine 被引量:3
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作者 Bradley Forbes Nicholas Vlachopoulos +2 位作者 Mark S.Diederichs Andrew J.Hyett Allan Punkkinen 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2020年第3期427-448,共22页
A recent research campaign at a Canadian nickel-copper mine involved instrumenting a hard rock sill drift pillar with an array of multi-point rod extensometers,distributed optical fibre strain sensors,and borehole pre... A recent research campaign at a Canadian nickel-copper mine involved instrumenting a hard rock sill drift pillar with an array of multi-point rod extensometers,distributed optical fibre strain sensors,and borehole pressure cells(BHPCs).The instrumentation spanned across a 15.24 m lengthwise segment of the relatively massive granitic pillar situated at a depth of 2.44 km within the mine.Between May 2016 and March 2017,the pillar’s displacement and pressure response were measured and correlated with mining activities on the same level as the pillar,including:(1)mine-by of the pillar,(2)footwall drift development,and(3)ore body stoping operations.Regarding displacements of the pillar,the extensometers provided high temporal resolution(logged hourly)and the optical fibre strain sensors provide high spatial resolution(measured every 0.65 mm along the length of each sensor).The combination of sensing techniques allowed centimetre-scale rock mass bulking near the pillar sidewalls to be distinguished from microstrain-scale fracturing towards the core of the pillar.Additionally,the influence and extent of a mine-scale schistose shear zone transecting the pillar was identified.By converting measured rock mass displacement to velocity,a process was demonstrated which allowed mining activities inducing displacements to be categorised by time-duration and cumulative displacement.In over half of the analysed mining activities,displacements were determined to prolong for over an hour,predominately resulting in submillimetre cumulative displacements,but in some cases multi-centimetre cumulative displacements were observed.This time-dependent behaviour was more pronounced within the vicinity of the plumb shear zone.Displacement measurements were also used to assess selected support member load and elongation mobilisation per mining activity.It was found that a combined static load and elongation capacity of reinforcing members was essential to maintaining excavation stability,while permitting gradual shedding of stress through controlled pillar sidewall displacements. 展开更多
关键词 Hard rock pillar ROCKBURST Rock mass bulking Distributed optical fibre strain sensing EXTENSOMETER In situ monitoring High stress Dynamic support
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Double pull specimen more suitable for measuring bond-slip relationship of FRP-to-concrete interface 被引量:1
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作者 杨奇飞 陆小华 熊光晶 《Journal of Central South University》 SCIE EI CAS 2010年第2期400-405,共6页
A new "conceptual" design named "double pull" specimen was proposed in order to measure the bond-slip(δ-τ) relationship of fiber reinforced polymer(FRP)-to-concrete interface more accurately.A fi... A new "conceptual" design named "double pull" specimen was proposed in order to measure the bond-slip(δ-τ) relationship of fiber reinforced polymer(FRP)-to-concrete interface more accurately.A finite element analysis(FEA) was performed for preliminarily evaluating the suitability of the proposed conceptual double pull specimen.Through the FEA,it was indicated that the FRP-to-concrete interface of the proposed conceptual specimen might subject to a much higher load level than that of the most commonly used simple shear specimen,showing a great potential for measuring δ-τ relationship more accurately.In the light of the conceptual specimen,a kind of "practical" double pull specimen was developed and proved to be more suitable for measuring δ-τ relationship through an exploratory experimental study with 20 specimens.Consequently,an experimental program with 10 double pull specimens was performed for measuring the ultimate slip δu which was difficult to capture by using the existing specimens.It is shown that the range of δu is 0.31-0.52 mm based on the test results.The suggestion for improving the measure method is also put forward. 展开更多
关键词 fiber reinforced polymer (FRP) concrete BOND-SLIP ultimate slip double pull specimen EXTENSOMETER
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Digital image correlation based high-speed crack tip locatingmethod and its application 被引量:1
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作者 曹彦彦 马沁巍 郭文婧 《Journal of Beijing Institute of Technology》 EI CAS 2016年第1期7-16,共10页
Based on a digital image correlation(DIC)method with the measurements of a high speed crack's displacement and strain fields,a technique to accurately and automatically locate its crack tip has been developed.The c... Based on a digital image correlation(DIC)method with the measurements of a high speed crack's displacement and strain fields,a technique to accurately and automatically locate its crack tip has been developed.The crack tip is identified by finding the abrupt jump on the opening(or dislocation)curve of a point on the trace of the crack propagation,while the opening is measured through a virtual extensometer technique and the abrupt jump is identified by finding the peak on the curve.The method was verified using a specially designed experiment and applied to measure the critical crack tip opening angle of a rock sample.Because the involvement of analytical models has been avoided and then the good performance could be ensured for low resolution speckle images,this technique is expected to be very useful in the quantitative study of high speed cracks in experiments using high speed cameras. 展开更多
关键词 digital image correlation(DIC) high speed crack crack tip virtual extensometer crack tip opening angle
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Development of a new differential extensometer
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作者 Lu Chongwu Yang Jiang 《Geodesy and Geodynamics》 2011年第1期77-80,共4页
This paper describes a new differential extensometer, which has a baseline rod in suspension with both ends free, and some preliminary test results. Compared with a traditional differential extensometer, which has one... This paper describes a new differential extensometer, which has a baseline rod in suspension with both ends free, and some preliminary test results. Compared with a traditional differential extensometer, which has one end of the baseline rod fixed to the ground, this instrument is less affected by commonly encountered interferences ,including environment vibration, momentary power failure, and power noise. 展开更多
关键词 EXTENSOMETER STRAIN differential structure TEST
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Performance analysis of a new baseline-based SS-Y extensometer
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作者 Linbin Wu Zhaosheng Nie 《Geodesy and Geodynamics》 2018年第5期418-423,共6页
In order to solve the problems in the observation with the SS-Y extensometer, such as background noise and discontinuity of earth tide curve, this paper proposed to improve the stability of the instrument and the smoo... In order to solve the problems in the observation with the SS-Y extensometer, such as background noise and discontinuity of earth tide curve, this paper proposed to improve the stability of the instrument and the smoothness of the earth tide curve by improving the baseline structure of the instrument. In this study, a new φ20*1.2 invar tube was introduced in replacement of the existing φ6 invar rod as the baseline of the instrument and compared with the existing φ6 invar rod on the instrument’s linearity,sensitivity and other indexes. Firstly, the SS-Y extensometers using φ6 invar rod and cp20*1.2 invar tube were tested. Test results were then calculated, and accuracy errors of the instruments based on the two baselines were obtained. Finally, their accuracy errors and earth tide curves were compared. Results showed that, compared with the extensometer based on the existing φ6 invar rod, the extensometer based on the new φ20*1.2 invar tube was superior in performance, with linearity error reducing to 0.495% from 0.937%, sensitivity increasing to 68.65 mV/μm from 65.46 mV/μm, and earth tide curve growing more stable and continuous. 展开更多
关键词 Invar tube EXTENSOMETER Ground deformation Background noise Earth tide
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Detecting the Earthquake Excited Spheroidal Free Oscillation of the Earth by Use of Observational Data at Huzhou Seismic Station
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作者 Fang Yanxun Bian Genfa +1 位作者 Hui Ruoyu Sun Zongqiang 《Earthquake Research in China》 CSCD 2016年第4期584-593,共10页
By using the digital observations of the pendulum tiltmeter, water tube tiltmeter,extensometer and volumetric strainmeter at Huzhou station and with the power spectrum density estimation method,we acquired the_0S_5-_0... By using the digital observations of the pendulum tiltmeter, water tube tiltmeter,extensometer and volumetric strainmeter at Huzhou station and with the power spectrum density estimation method,we acquired the_0S_5-_0S_50 fundamental sphere free oscillations caused by the Japan earthquake on March 11,2011,then compared it with the PREM model. The relative errors are mostly bigger than 1.2‰. The extensometer and volume strainmeter can clearly detect _0S_2,_0S_3and_0S_4,which are closely related to the deep structure and earth's interior. 展开更多
关键词 Pendulum tiitmeter Water tube tiitmeter EXTENSOMETER Volumetric strainmeter Free oscillation of the earth
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Monitoring Instrumentation in Underground Structures
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作者 Alireza Maghsoudi Behzad Kalantari 《Open Journal of Civil Engineering》 2014年第2期135-146,共12页
Nowadays underground structures are very important. Based on observations of engineering;properties during geotechnical construction are an integral part of the design of underground structures. This research presents... Nowadays underground structures are very important. Based on observations of engineering;properties during geotechnical construction are an integral part of the design of underground structures. This research presents instrumentation as a tool to assist with these measurement observations, determine the need for modifications to loading or support arrangement. Also apart from above construction control, instrumentation is also indispensable for site investigation, design verification and safety of the structure. Instrumentation used in the construction of tunnels and subways can be implemented in three stagesbefore, during operation and during operation are examined. Metro Railway Tunnels are constructed in populated area and have a more comprehensive instrumentation and monitoring program that additionally includes monitoring of ground conditions, underground water levels, tilt and settlement of nearby buildings or other structures of interest in the vicinity of the tunnel alignment. Instrumentation monitoring for metro railway tunnels includes monitoring of the structures under construction together with the ground, buildings and other facilities within the predicted zone of influence. Furthermore, instrumentation and subway tunnels in and around them increase accuracy of the different layers of the earth and excavation of the surrounding structures and make safety and accuracy. This paper presents the features of sophisticated instrumentation available today for geotechnical monitoring. A wide range of sophistic have been described with their applications ted electronic and mechanical instrumentation with different instrumentation schemes used to meet the requirements of different types of structures. 展开更多
关键词 Tunnel Hydraulic FRACTURING Flat Jack TEST Press TEST (PMT) Plate Bearing TEST EXTENSOMETER PIEZOMETER Seismic Refraction Tomography (SRT)
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