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2 results on '"Slip ratio"'

1. Aircraft Anti-Skid Brake Control Based on High-Speed on-off Valve

Author

Li Wei, Zhang Hu, and Huang Xiaoya

Subjects
aircraft anti-skid brake, high-speed on-off valve, slip ratio, large close loop, Engineering (General). Civil engineering (General), TA1-2040
Abstract

Aircraft hydraulic brake system usually use pressure servo valve for anti-skid brake control. As pressure servo valve realizes the pressure closed loop by hydraulic feedback loop, this structure increased the complexity of the processing and manufacturing, restricted the pressure closed loop parameters adjustment, and increased the difficulty of debugging the system design. Pressure servo valve is expensive and difficult to process, poor ability to resist pollution. This paper proposed a slip ratio large closed loop aircraft anti-skid brake control method based on high-speed on-off valve, built the model of aircraft ground vertical taxiing and slip ratio large closed loop control algorithm in the MATLAB/SIMULINK, and built the model of aircraft hydraulic brake system based on on-off valve in the AMESim and a joint simulation was carried out. The simulation results show that the aircraft anti-skid brake control method based on high-speed on-off valve is feasible, and the on-off valve is cheap with strong ability to resist pollution, easy processing and manufacturing and so on, showing a good application prospect.

Published
2015
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2. Rock climbing belay device analysis, experiments and modeling

Author

Jean-Daniel Brabant, Lionel Manin, Marc Bissuel, Matthieu Richard, Laboratoire de Mécanique des Contacts et des Structures [Villeurbanne] (LaMCoS), Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), and Colin, Anne-Marie

Subjects
Tension (physics), business.industry, Climbing, Brake, escalade, Slip ratio, Structural engineering, Impact, business, ComputingMilieux_MISCELLANEOUS, Mathematics, Slip (vehicle dynamics), Rope
Abstract

Amazingly no standard exists for belay devices used in rock or ice climbing. This paper presents an analysis performed on several belay devices that permits their comparison in terms of characteristics and efficiency. The belay device characterization consists in testing the brakes in the case of a given fall arrest in a testing room. Here, a belay device is characterized by its braking coefficient, the rope slip through the brake till the arrest of the fall and the impact load on the last runner. The braking coefficient is the ratio between the rope tensions on the tight and slack sides of the belay device. A device called “virtual hand” has been developed, it tries to reproduce the belayer hand action on the rope during the fall arrest, and it also enables the measurement of the load on the brake and the control of the rope tension on the belayer hand side. The fall arrest intensity or brutality is evaluated from the measurements of the rope slip in the brake and the load on the last runner. The analysis of the three measured characteristics enables the comparison of the six belay devices tested. It appears that these three quantities are related, indeed the larger the braking coefficient the lower the rope slip and the higher the impact load. The energy of the fall is absorbed over a shorter time period for belay device having a high braking coefficient. Therefore, an efficient braking gives way to a high impact force on the climber and a more brutal arrest of the fall. A basic model for the brake has been implemented in an already developed climber fall arrest model. Comparison of experimental and numerical results is made and is satisfactorily.

Published
2006

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