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Improvement of Tightening Reliability of Bolted Joints Using Elliptical Confidence Limit in Calibrated Wrench Method

Tokyo Metropolitan University-Soichi Hareyama, Ken-ichi Manabe, Satoshi Kobayashi
  • Technical Paper
  • 2020-01-0218
To be published on 2020-04-14 by SAE International in United States
The calibrated wrench method is used in the tightening of bolts in manufacturing industries in the case of a large amount of tightening work. It is important to apply a large initial clamping force to ensure tightening reliability and prevent self-loosening, fatigue breakage, and so forth. In this method, the clamping force of bolted joints is controlled using a torque wrench. However, since the clamping force is indirectly applied by a wrench, it varies greatly in the case of a large amount of tightening in a factory. Therefore, the calibrated wrench method is not so accurate from the viewpoint of clamping force control. It is conventionally thought that the distribution of the clamping force has the shape of a rhombus. When tightening torque and clamping force are considered to be two independent random variables, the clamping force is distributed within an elliptical confidence limit. Here, we show that the distribution of equivalent stress also has an elliptical confidence limit. Considering the permitted limit for working load stress on a bolted joint, the elliptical distribution has…
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Loosening Lifetime and Residual Clamping Force Prediction Method on Bolted Joints and Evaluation Criterion of Clamping Force Level for Prevention of Loosening Failure

Tokyo Metropolitan University-Soichi Hareyama, Ken-ichi Manabe, Satoshi Kobayashi
Published 2019-04-02 by SAE International in United States
To secure the reliability of bolted joints, high clamping force (axial tension) is required to prevent fatigue breakage or loosening failure, and so on. In this paper, at first, we observe the behavior of the initial clamping force decrease tendency (loosening phenomenon) obtained by tightening the bolt used in the actual machine (large forklift) during operation. Based on our previous research, there is a strong linear relationship on log-log paper of loosening phenomenon between decrease tendency of clamping force and distance travelled (or passage of time). By utilizing its properties, we show estimation method of residual clamping force such as "How much the clamping force is remaining after the tens of thousands of hours (kilometers)?" Also, a method for estimating loosening lifetime with respect to residual clamping force level is shown. Finally, we examine evaluation criteria such as "Is the residual clamping force sufficient for prevention of loosening failure?" The limit surface pressure is examined as the upper limit clamping force. As the lower limit clamping force, the allowable value of the external transverse force…
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Effect of Driver Posture on Driving Characteristics when Control is Passed from an Autonomous Driving System to a Human Driver

Tokyo Metropolitan University-Shoko Oikawa
NTSEL-Yasuhiro Matsui
Published 2018-04-03 by SAE International in United States
SAE International defines six levels of autonomous driving system, four of which include a change of control from the system to the driver in certain conditions. When vehicle control changes from the system to a human driver, a safe transition time is necessary. The present study focuses on level 3 automation, in which the system controls driving in ordinary conditions, but the human driver is expected to intervene in emergency situations. The aim of this study was to investigate the relationship between driver posture and transition time. Driver posture included four components: backrest angle, seat position, foot position, and arm position. These were adjusted to investigate a total of 30 posture patterns. In addition, the situation in which the driver was not watching the road, but instead using a tablet computer was investigated. The driver’s braking and steering reaction times were measured for a highway-driving scenario in which a truck dropped cargo in front of the vehicle. Acoustic and optical warnings were presented to the driver when the autonomous driving system was disengaging. The results…
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Working Load Measurement and Analysis of Bolted Joint under Off-road Vehicle Operation

Tokyo Metropolitan University-Soichi Hareyama, Ken-ichi Manabe
Published 2018-04-03 by SAE International in United States
In this study, we propose a method of measuring and analyzing the load on bolted joints used in a machine under off-road vehicle operation. Working load measurement under actual machine operation and the results of its analysis are shown as load frequency diagrams. An example of the measurement analysis of a load (three types of load: axial force, bending moment, and torsional torque) added to a bolted joint shank during actual machine operation is shown. In this paper, we describe how to apply the results of load analysis to the load condition at the design and experimental development stages.
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Residual Clamping Force Estimation and Lifetime Prediction to Loosening Failure of Bolted Joints

Tokyo Metropolitan University-Soichi Hareyama, Ken-ichi Manabe
Hitachi Construction Machinery-Takayuki Shimodaira, Akio Hoshi
Published 2017-03-28 by SAE International in United States
This investigation describes a method for estimating the absolute lock effect in bolted joint. Observation results of loosening phenomenon in industrial vehicle are analyzed for the linear relation by the proposed regression formula. Based on the relation, in early stages of the development test, the rate of clamping force decrease can be estimated accurately after prolonged operation by measuring the clamping force behavior. The tendency to decrease is observed about the depression type and working load type loosening. For evaluation design bases, the residual clamping force estimation chart is established. The L-N (Loosening Lifetime - Number of Cycles to Loosening N) diagram is proposed for the loosening lifetime prediction for working load type loosening also. Using the loosening damage (cumulative decrease of clamping force) and L-N diagram, the lifetime to loosening failure can be predicted accurately for the locking device and method as an absolute evaluation.
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Traffic Accidents Involving Cyclists Identifying Causal Factors Using Questionnaire Survey, Traffic Accident Data, and Real-World Observation

Tokyo Metropolitan University-Shigeru Aomura
National Traffic Safety and Environment Laboratory-Shoko Oikawa, Yasuhiro Matsui
Published 2016-11-07 by The Stapp Association in United States
The purpose of this study is to clarify the mechanism of traffic accidents involving cyclists. The focus is on the characteristics of cyclist accidents and scenarios, because the number of traffic accidents involving cyclists in Tokyo is the highest in Japan. First, dangerous situations in traffic incidents were investigated by collecting data from 304 cyclists in one city in Tokyo using a questionnaire survey. The survey indicated that cyclists used their bicycles generally while commuting to work or school in the morning. Second, the study investigated the characteristics of 250 accident situations involving cyclists that happened in the city using real-world bicycle accident data. The results revealed that the traffic accidents occurred at intersections of local streets, where cyclists collided most often with vehicles during commute time in the morning. Third, cyclists’ behavior was observed at a local street intersection in the morning in the city using video pictures. In one hour during the morning commute period, 250 bicycles passed through the intersection. The results indicated that one of the reasons for traffic accidents involving…
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Experimental Method Extracting Dominant Acoustic Mode Shapes for Automotive Interior Acoustic Field Coupled with the Body Structure

SAE International Journal of Passenger Cars - Mechanical Systems

Tokyo Metropolitan University-Takuya Yoshimura
Nissan Motor Co., Ltd.-Hiromichi Tsuji, Shinichi Maruyama, Eiji Takahashi
  • Journal Article
  • 2013-01-1905
Published 2013-05-13 by SAE International in United States
For a numerical model of vibro-acoustic coupling analysis, such as a vehicle noise and vibration, both structural and acoustical dynamic characteristics are necessary to replicate the physical phenomenon. The accuracy of the analysis is not enough for substituting a prototype phase with a digital phase in the product development phases. One of the reasons is the difficulty of addressing the interior acoustical characteristics due to the complexity of the acoustical transfer paths, which are a duct and a small hole of trim parts in a vehicle. Those complex features affect on the nodal locations and the body coupling surface of acoustic mode shapes. In order to improve the accuracy of the analysis, the physical mechanisms of those features need to be extracted from experimental testing.The accuracy of the vibro-acoustic coupled system model for the low frequency range depends on how accurately modal characteristics are represented at the input, output, and the structure-acoustic coupling surface. Therefore, this study focus on extracting the detailed acoustic mode shapes on the coupling surface for the improvement of the model…
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Real-time Analysis of Benzene in Exhaust Gas from Driving Automobiles Using Jet-REMPI Method

Tokyo Metropolitan University-Jun Matsumoto
CNRS-Kotaro Tanaka
Published 2009-11-02 by SAE International in United States
Real-time analysis of benzene in automobile exhaust gas was performed using the Jet-REMPI (supersonic jet / resonance enhanced multi-photon ionization) method. Real-time benzene concentration of two diesel trucks and one gasoline vehicle driving in Japanese driving modes were observed under ppm level at 1 s intervals. As a result, it became obvious that there were many differences in their emission tendencies, because of their car types, driving conditions, and catalyst conditions. In two diesel vehicle, benzene emission tendencies were opposite. And, in a gasoline vehicle, emission pattern were different between hot and cold conditions due to the catalyst conditions.
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Simultaneous Measurements of Aromatic Hydrocarbons in Exhaust using a Laser Ionization Method

SAE International Journal of Engines

Tokyo Metropolitan University-Jun Matsumoto
CNRS-Kotaro Tanaka
  • Journal Article
  • 2009-01-2742
Published 2009-11-02 by SAE International in United States
A simultaneous multi-composition analyzing (SMCA) resonance enhanced multi-photon ionization (REMPI) system was used to investigate gasoline engine exhaust. Observed peaks for exhaust were smaller mass numbers than those from diesel exhaust. However, large species up to three ring aromatics were observed suggesting that soot precursor forms even in the gasoline engine. At low catalyst temperature condition, the reduction efficiencies of a three-way catalyst were higher for higher mass numbers. This result indicates that the larger species accumulate in the catalyst or elsewhere due to their lower vapor pressures. To evaluate the emission of low volatility species, the accumulation should be taken into account. In the hot mode, reduction efficiencies for aromatic species of three-way catalyst were almost 99.5% however, they fall to 70% in the cold start condition.
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