The Experts below are selected from a list of 5745 Experts worldwide ranked by ideXlab platform
Pingfa Feng - One of the best experts on this subject based on the ideXlab platform.
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jaw chuck stiffness and its influence on dynamic Clamping Force during high speed turning
International Journal of Machine Tools & Manufacture, 2008Co-Authors: Pingfa Feng, Dingwen Yu, Zhijun Wu, Eckart UhlmannAbstract:The spindle rotational speed of machine tools has become steadily higher due to the application of high speed cutting (HSC) technology. Higher spindle speed leads to greater demands on Clamping systems. A basic problem with the application of jaw-chucks for Clamping workpieces during high-speed turning is the huge centrifugal Force that acts on chuck-jaws. This centrifugal Force reduces effectiveness of the dynamic Clamping Force, making the HSC process dangerous. We have developed a computational model for determining the dynamic Clamping Force of jaw-chucks during high-speed turning that takes into account the influence of the stiffness behaviours of the chuck and workpiece. This model was verified by means of FE-analyses and experimental investigations. The theoretical model we introduced has a high computation accuracy both for conventional and modern chucks, such as power-operated wedge hook chucks with centrifugal Force compensation. The exact computation of dynamic Clamping Force ensures a safe high-speed turning process, and makes it possible to fully utilize the potential of jaw-chucks at high rotational speeds. The study results provide reliable theoretical and technical supports for the optimization of the design and application of jaw-chucks.
Job Ha - One of the best experts on this subject based on the ideXlab platform.
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estimation of Clamping Force in high tension bolts through ultrasonic velocity measurement
Ultrasonics, 2006Co-Authors: Kyung-young Jhang, Hai Hua Quan, Job HaAbstract:Abstract The estimation of Clamping Force has been regarded as the main issue in the maintenance of high-tension bolts. This paper proposes a method which uses the dependency of ultrasonic velocity on stress based on the nonlinear elastic effect. The variation of ultrasonic velocity in the range of actual stress acting in the bolt is very small so that the precise measurement of ultrasonic velocity is needed. In this paper, we adopt a method to measure ultrasonic velocity, where the TOF (time of flight) of a tone-burst ultrasonic wave is precisely measured by using the phase detection technique. In order to verify the usefulness of the proposed method, two kinds of experiments are carried out. The first one measures ultrasonic velocity when the bolt is stressed by the tension tester, and from this, the exact axial Force acting in the bolt can be determined. The results show good agreement with the expected linear relationship between ultrasonic velocity and axial stress. The second experiment measures ultrasonic velocity when the bolt is stressed by the torque wrench. The results show that ultrasonic velocity decreased as the torque increased, which is identical to the theoretically expected tendency. From these results, it can be said that the proposed method is adequate in evaluating Clamping Force in high-tension bolts.
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Ultrasonic Estimation of Clamping Force in High-Tension Bolts
Key Engineering Materials, 2006Co-Authors: Kyung-young Jhang, Hai Hua Quan, Job HaAbstract:High-tension bolts have been used widely for the Clamping of many kinds of large structures. In these bolts, the estimation of Clamping Force has been regarded as the main issue in the evaluation of Clamping condition. This paper proposes a method using ultrasonic wave, which is based on the dependency of sound speed on the stress. In order to verify the usefulness of the proposed method, two kinds of experiments are carried out. The first one involves the measurement of sound speed when the bolt is stressed by the tension tester, and here, the relationship between the exact axial Force and sound speed is calibrated. The result shows good agreement with the expected linear relationship between sound speed and axial stress. The second experiment involves the measurement of axial stress by the proposed method when the bolt is stressed by the torque wrench. The results are coincident to the strain gage measurement. From these results, we can conclude that the proposed method is indeed useful in evaluating Clamping Force in high-tension bolts.
Eckart Uhlmann - One of the best experts on this subject based on the ideXlab platform.
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jaw chuck stiffness and its influence on dynamic Clamping Force during high speed turning
International Journal of Machine Tools & Manufacture, 2008Co-Authors: Pingfa Feng, Dingwen Yu, Zhijun Wu, Eckart UhlmannAbstract:The spindle rotational speed of machine tools has become steadily higher due to the application of high speed cutting (HSC) technology. Higher spindle speed leads to greater demands on Clamping systems. A basic problem with the application of jaw-chucks for Clamping workpieces during high-speed turning is the huge centrifugal Force that acts on chuck-jaws. This centrifugal Force reduces effectiveness of the dynamic Clamping Force, making the HSC process dangerous. We have developed a computational model for determining the dynamic Clamping Force of jaw-chucks during high-speed turning that takes into account the influence of the stiffness behaviours of the chuck and workpiece. This model was verified by means of FE-analyses and experimental investigations. The theoretical model we introduced has a high computation accuracy both for conventional and modern chucks, such as power-operated wedge hook chucks with centrifugal Force compensation. The exact computation of dynamic Clamping Force ensures a safe high-speed turning process, and makes it possible to fully utilize the potential of jaw-chucks at high rotational speeds. The study results provide reliable theoretical and technical supports for the optimization of the design and application of jaw-chucks.
T N Chakherlou - One of the best experts on this subject based on the ideXlab platform.
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investigation of bolt Clamping Force on the fatigue life of double lap simple bolted and hybrid bolted bonded joints via experimental and numerical analysis
Engineering Failure Analysis, 2014Co-Authors: F Esmaeili, T N Chakherlou, Mohammad ZehsazAbstract:Abstract In this research, the effect of bolt Clamping Force on the fatigue life of double lap simple bolted and hybrid (bolted/bonded) joints have been studied both experimentally and numerically. To do so, two kinds of joints, i.e. double lap simple and hybrid (bolted/bonded) joints were studied. For each kind of the joints, three sets of specimens were prepared and subjected to tightening torque of 1, 2.5 and 5 N m and then fatigue tests were carried out at different cyclic longitudinal load levels. Experimental tests revealed that the hybrid joints have higher fatigue life in comparison with the simple bolted joints. In the numerical method, finite element code was used to obtain stress distribution in the joint plates due to Clamping Force and longitudinal applied loads. Numerical simulation and experimental results showed that the fatigue life of specimens was improved by increasing the Clamping Force due to compressive stresses created around the hole. In addition, the investigation revealed the positive role of Clamping Force resulting from torque tightening on the fatigue life of both simple and hybrid joints.
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finite element investigations of bolt Clamping Force and friction coefficient effect on the fatigue behavior of aluminum alloy 2024 t3 in double shear lap joint
Engineering Failure Analysis, 2013Co-Authors: T N Chakherlou, Mir Jalil Razavi, Babak AbazadehAbstract:Abstract In this paper, the effect of bolt Clamping Force on the fatigue life of bolted double shear lap joints was investigated numerically. To do so, finite element simulation results were used to illustrate the trends occurred in experimental fatigue tests showing the effect of bolt Clamping on improving the fatigue life of double shear lap joints. The results show that Clamping Force decreases the resultant longitudinal stress at the hole edge thus the fatigue life increases compared to clearance fit specimens. In general, at higher tightening torque longer fatigue lives were achieved, however, below a certain load level the life improvement was discontinued because of fretting occurrence. Also lubricating the specimens reduces the advantages of the Clamping Force.
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investigating Clamping Force variations in al2024 t3 interference fitted bolted joints under static and cyclic loading
Materials & Design, 2012Co-Authors: T N Chakherlou, B AbazadehAbstract:Abstract In this paper the variation of bolt Clamping Force in interference fitted-bolt clamped aluminum 2024-T3 specimens in double shear lap joints have been investigated under static and cyclic loads. In experimental part of the study, static or cyclic longitudinal remote loads have been applied to the joint and the variations of bolt Clamping Forces were measured in the tests. Finite element analysis was also performed and the results were compared with the results of statically loaded experimental tests. The results showed an initial reduction of the Clamping Force followed by an increase for bigger longitudinal static load. During cyclic loading in experimental tests, bolt Clamping Force reduction was observed in the first 1000 cycles, especially for joints with higher size of the interference fit. This reduction was due to the scrape of the protruded region around the hole, left from bolt interference fitting, on the exit plane of the main part.
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On the Variation of Clamping Force in Bolted Double Lap Joints Subjected to Longitudinal Loading: A Numerical and Experimental Investigation
Strain, 2011Co-Authors: T N Chakherlou, Mir Jalil Razavi, A.b. AghdamAbstract:: This study investigates the variation of Clamping Force and its concomitant effects on the performance of bolted double lap joints subjected to longitudinal loading. Two different amounts of Clamping Force were applied to bolted double lap joints made of Aluminium 2024-T3, and variations of Clamping Force were measured under the application of longitudinal loading. Finite element modelling was also performed to compare with experiments. The results unanimously revealed a gradual initial reduction of Clamping Force followed by a significant increase as the longitudinal load was increased. Also affected, was the load transfer mechanism in the joint resulting in variation of friction Force between the plates, but in a different trend compared to Clamping Force. Finally, the key parameters have been discussed and highlighted pertaining to the performance of the joint.
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reduction in Clamping Force due to applied longitudinal load to aerospace structural bolted plates
Aerospace Science and Technology, 2009Co-Authors: Reza Hashemi Oskouei, T N ChakherlouAbstract:The main purpose of the present work is to experimentally and numerically study why and how the magnitude of the bolt Clamping Force reduces in the aerospace structural bolted plates when they are subjected to a longitudinal tensile load. In the experimental method, a holed plate of aluminium alloy 7075-T6 was clamped using a single bolt fastener, and then tested under an increasing static longitudinal tensile load. The bolt Clamping magnitude was determined by using the measured axial compressive strains of a steel bush placed between the nut and plate. Two clamped specimens with different initial Clamping Forces were studied. In each specimen the actual Clamping Forces were determined during the longitudinal loading on the plate. In the numerical method, a three-dimensional (3D) finite element model was generated in order to simulate and quantify the bolt Clamping Force in the plate model loaded in tension. Both experimental and numerical results showed that the Clamping Force reduces considerably in the aluminium bolted plates under the longitudinal tensile loading. This is because of the transverse contraction of the plate material that causes the clamped material to release from the initial compression, and as a result, the Clamping Force to relax.
Kyung-young Jhang - One of the best experts on this subject based on the ideXlab platform.
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estimation of Clamping Force in high tension bolts through ultrasonic velocity measurement
Ultrasonics, 2006Co-Authors: Kyung-young Jhang, Hai Hua Quan, Job HaAbstract:Abstract The estimation of Clamping Force has been regarded as the main issue in the maintenance of high-tension bolts. This paper proposes a method which uses the dependency of ultrasonic velocity on stress based on the nonlinear elastic effect. The variation of ultrasonic velocity in the range of actual stress acting in the bolt is very small so that the precise measurement of ultrasonic velocity is needed. In this paper, we adopt a method to measure ultrasonic velocity, where the TOF (time of flight) of a tone-burst ultrasonic wave is precisely measured by using the phase detection technique. In order to verify the usefulness of the proposed method, two kinds of experiments are carried out. The first one measures ultrasonic velocity when the bolt is stressed by the tension tester, and from this, the exact axial Force acting in the bolt can be determined. The results show good agreement with the expected linear relationship between ultrasonic velocity and axial stress. The second experiment measures ultrasonic velocity when the bolt is stressed by the torque wrench. The results show that ultrasonic velocity decreased as the torque increased, which is identical to the theoretically expected tendency. From these results, it can be said that the proposed method is adequate in evaluating Clamping Force in high-tension bolts.
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Ultrasonic Estimation of Clamping Force in High-Tension Bolts
Key Engineering Materials, 2006Co-Authors: Kyung-young Jhang, Hai Hua Quan, Job HaAbstract:High-tension bolts have been used widely for the Clamping of many kinds of large structures. In these bolts, the estimation of Clamping Force has been regarded as the main issue in the evaluation of Clamping condition. This paper proposes a method using ultrasonic wave, which is based on the dependency of sound speed on the stress. In order to verify the usefulness of the proposed method, two kinds of experiments are carried out. The first one involves the measurement of sound speed when the bolt is stressed by the tension tester, and here, the relationship between the exact axial Force and sound speed is calibrated. The result shows good agreement with the expected linear relationship between sound speed and axial stress. The second experiment involves the measurement of axial stress by the proposed method when the bolt is stressed by the torque wrench. The results are coincident to the strain gage measurement. From these results, we can conclude that the proposed method is indeed useful in evaluating Clamping Force in high-tension bolts.