The mechanics of a climbing fall with a belayer who can be lifted

2021 ◽  
pp. 175433712199261
Author(s):  
Ulrich Leuthäusser
Keyword(s):  
Exact Solution ◽  
Impact Force ◽  
Initial Position ◽  
Minimum Mass ◽  
Trade Off ◽  
Linear Elastic ◽  
Stopping Distance ◽  
Sport Climbing ◽  
Force Reduction ◽  
Maximum Impact Force

In sport climbing, a common method of belaying is to use a static rope brake attached to the belayer’s harness, but the belayer can move freely. This paper investigates the dynamics of a climbing fall with such a belayer. The dynamics are nontrivial because of the belayer’s constraint to be always at or above his initial position. An exact solution for a linear elastic rope is presented. Compared to a fix-point belay, one obtains a considerable force reduction on the belay-chain. However, there is a trade-off of a longer stopping distance of both climber and belayer. In order to calculate the stopping distance, friction between rope and the top carabiner has been taken into account. Closed-form formulas allow for calculating the maximum impact force, as well as the minimum mass of the belayer which is necessary to hold a fall from a certain height.

scholarly journals Experimental Study of the Debris Flow Slurry Impact and Distribution

2018 ◽  
Vol 2018 ◽  
pp. 1-15 ◽  
Author(s):  
Haixin Zhao ◽  
Lingkan Yao ◽  
Yong You ◽  
Baoliang Wang ◽  
Cong Zhang
Keyword(s):  
Debris Flow ◽  
Debris Flows ◽  
Impact Force ◽  
Influence Factors ◽  
Flume Experiment ◽  
Middle Point ◽  
Laboratory Flume ◽  
Critical Issues ◽  
Maximum Impact Force ◽  
The Impact

In this study, we present a new method to calculate debris flow slurry impact and its distribution, which are critical issues for designing countermeasures against debris flows. There is no unified formula at present, and we usually design preventive engineering according to the uniform distribution of the maximum impact force. For conducting a laboratory flume experiment, we arrange sensors at different positions on a dam and analyze the differences on debris flow slurry impact against various densities, channel slopes, and dam front angles. Results show that the force of debris flow on the dam distributes unevenly, and that the impact force is large in the middle and decreases gradually to the both sides. We systematically analyze the influence factors for the calculation of the maximum impact force in the middle point and give the quantitative law of decay from the middle to the sides. We propose a method to calculate the distribution of the debris flow impact force on the whole section and provide a case to illustrate this method.

scholarly journals Comparison of branded rugby headguards on their effectiveness in reducing impact on the head

2018 ◽  
Vol 4 (1) ◽  
pp. e000361 ◽  
Author(s):  
Erin R A Frizzell ◽  
Graham P Arnold ◽  
Weijie Wang ◽  
Rami J Abboud ◽  
Tim S Drew
Keyword(s):  
Impact Force ◽  
Linear Acceleration ◽  
Baseline Measurement ◽  
Peak Acceleration ◽  
Impact Forces ◽  
Impact Attenuation ◽  
The Mean ◽  
Force Reduction ◽  
The Right ◽  
The Impact

AimTo compare the available brands of rugby headguards and evaluate their impact attenuation properties at various locations on the cranium, with regard to concussion prevention.MethodsSeven different branded headguards were fitted onto a rigid headform and drop-tested in three different positions. An accelerometer measured the linear acceleration the headform experienced on impact with the ground. Each test involved dropping the headform from a height that generated 103.8 g on average when bare, which is the closest acceleration to the upper limit of the concussion threshold of 100 g. A mean peak acceleration for each drop position was calculated and compared with the bare baseline measurement.ResultsEach headguard demonstrated a significant decrease in the mean peak acceleration from the baseline value (all p≤0.01). Overall the Canterbury Ventilator was the most effective headguard, decreasing the impact force on average by 47%. The least effective was the XBlades Elite headguard, averaging a force reduction of 27%. In five of the seven headguards, the right side of the headwear was the most effective at reducing impact force.ConclusionOverall, the results indicate that it would be beneficial to wear a headguard during rugby in order to reduce the impact forces involved in head collisions. There was also a clear difference in performance between the tested brands, establishing the Canterbury headguard as the most effective. However, only one model of headguard from each brand was tested, so further research evaluating all other models should be considered.

Impact Force Reduction Using Variable Stiffness with an Optimal Approach for Falling Robots

2017 ◽  
pp. 404-415
Author(s):  
Juan Calderon ◽  
Gustavo A. Cardona ◽  
Martin Llofriu ◽  
Muhaimen Shamsi ◽  
Fallon Williams ◽  
...  
Keyword(s):  
Impact Force ◽  
Variable Stiffness ◽  
Force Reduction ◽  
Optimal Approach

Stochastic Analysis of Impact Loads on Marine Structures

2012 ◽  
Author(s):  
Jens B. Helmers ◽  
Hui Sun ◽  
Tormod Landet ◽  
Torgrim Driveklepp
Keyword(s):  
Stochastic Analysis ◽  
Impact Force ◽  
Plate Theory ◽  
Vertical Motion ◽  
Vertical Position ◽  
Marine Structures ◽  
Sea State ◽  
Stochastic Effects ◽  
Maximum Penetration ◽  
Maximum Impact Force

An efficient Monte Carlo method is developed to perform the stochastic analysis of slamming loads on marine structures. The probability distribution of the maximum impact force during slamming is established for a given stationary sea state. The method is demonstrated by using a uniform wedge and Wagner’s flat plate theory. Stochastic effects related to deadrise angle, flow separation from the knuckle, vertical position of the structure, vertical motion and roll motion are investigated. The statistics of other parameters such as the duration of the slamming event and the maximum penetration of the structure into water are also assessed.

DYNAMIC CHARACTERISTICS MEASUREMENTS OF A FORCE TRANSDUCER AGAINST SMALL AND SHORT-DURATION IMPACT FORCES

2014 ◽  
Vol 21 (1) ◽  
pp. 59-66 ◽  
Author(s):  
Mitra Djamal ◽  
Kazuhide Watanabe ◽  
Kyohei Irisa ◽  
Irfa Aji Prayogi ◽  
Akihiro Takita ◽  
...  
Keyword(s):  
Short Duration ◽  
Dynamic Characteristics ◽  
Impact Force ◽  
Inertial Force ◽  
Small Mass ◽  
Force Transducer ◽  
Force Transducers ◽  
Impact Forces ◽  
Maximum Impact Force ◽  
The Impact

Abstract A method for evaluating the dynamic characteristics of force transducers against small and short-duration impact forces is developed. In this method, a small mass collides with a force transducer and the impact force is measured with high accuracy as the inertial force of the mass. A pneumatic linear bearing is used to achieve linear motion with sufficiently small friction acting on the mass, which is the moving part of the bearing. Small and short-duration impact forces with a maximum impact force of approximately 5 N and minimum half-value width of approximately 1 ms are applied to a force transducer and the impulse responses are evaluated.

scholarly journals 1712 Impact force reduction method using humanoid robot arm for inevitable collision

2012 ◽  
Vol 2012.18 (0) ◽  
pp. 27-28
Author(s):  
Yuuki KIMOTSU ◽  
Junpei HATAYAMA ◽  
Shinnya KOTOSAKA ◽  
Ryuuichi HODOSHIMA
Keyword(s):  
Humanoid Robot ◽  
Reduction Method ◽  
Impact Force ◽  
Robot Arm ◽  
Force Reduction

A Comparative Study on the Effect of Mechanical Compliance for a Safe Physical Human–Robot Interaction

2020 ◽  
Vol 142 (6) ◽  
Author(s):  
Yu She ◽  
Siyang Song ◽  
Hai-Jun Su ◽  
Junmin Wang
Keyword(s):  
Impact Force ◽  
Variable Stiffness ◽  
Human Robot Interaction ◽  
Design Parameters ◽  
Robot Dynamics ◽  
Robot Interaction ◽  
Promising Alternative ◽  
Mechanical Compliance ◽  
Maximum Impact Force ◽  
The Impact

Abstract In this paper, we study the effects of mechanical compliance on safety in physical human–robot interaction (pHRI). More specifically, we compare the effect of joint compliance and link compliance on the impact force assuming a contact occurred between a robot and a human head. We first establish pHRI system models that are composed of robot dynamics, an impact contact model, and head dynamics. These models are validated by Simscape simulation. By comparing impact results with a robotic arm made of a compliant link (CL) and compliant joint (CJ), we conclude that the CL design produces a smaller maximum impact force given the same lateral stiffness as well as other physical and geometric parameters. Furthermore, we compare the variable stiffness joint (VSJ) with the variable stiffness link (VSL) for various actuation parameters and design parameters. While decreasing stiffness of CJs cannot effectively reduce the maximum impact force, CL design is more effective in reducing impact force by varying the link stiffness. We conclude that the CL design potentially outperforms the CJ design in addressing safety in pHRI and can be used as a promising alternative solution to address the safety constraints in pHRI.

Three-Dimensional Liquid Sloshing Numerical Analysis on a New Designed Tank Container

2019 ◽  
Author(s):  
Wenjun Yue ◽  
Xu Chen
Keyword(s):  
Fluid Flow ◽  
Carrying Capacity ◽  
Impact Force ◽  
Three Dimensional ◽  
Economic Benefits ◽  
Cylindrical Vessel ◽  
Filling Ratio ◽  
Operating Conditions ◽  
New Type ◽  
Maximum Impact Force

Abstract Based on the conventional tank container which has a cylindrical vessel, a new structure of tank container was designed to improve the carrying capacity of the tank. Fluid flow inside the new tank container under different operating conditions (liquid filling ratio K, braking deceleration a, filling medium, no baffle and with baffles) was studied. A volume-of-fluid (VOF) method and a k-epsilon (k-ε) turbulence model were used to simulate the fluid flow. Results showed that all the factors studied in this work had an influence on the tank. The maximum impact force increased with the increasing of a and K. A clear linear positive correlation was found between the maximum impact force and braking deceleration. Besides, the maximum impact force had a relationship with the density of medium. Compared with the conventional tank container, the carrying capacity of the new type tank container increases by 11.8%, which means the new type tank container has better economic benefits.

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