1A2-F10 High-speed Throwing Motion Based on Wave Propagation

Abstract Stamping is one of the most used manufacturing processes, where real-time monitoring is quite difficult due to high speed of the mechanical press, which leads to deterioration of the accuracy of the products In the present work, a method is developed to model elastic waves propagation in solids to measure contact conditions between die and workpiece during stamping. A two-dimensional model is developed that reduces the wave propagation equations to two-dimensional equations. To simulate the wave propagation inside the die-workpiece model, the finite difference time domain (FDTD) method and modified Yee algorithm has been employed. The numerical stability of the wave propagation model is achieved through courant stability condition, i.e., Courant-Friedrichs-Lewy (CFL) number. Two cases, i.e., flat die-workpiece interface and inclined die-workpiece interface, are investigated in the present work. The elastic wave propagation is simulated with a two-dimension (2D) model of the die and workpiece using reflecting boundary conditions for different material properties. The experimental and simulation-based results of reflected and transmitted wave characteristics are compared for different materials in terms of reflected and transmitted wave height ratio and material properties such as acoustic impedance. It is found that the numerical simulation results are in good agreement with the experimental results.

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Time analysis of throwing motions to second base by baseball catchers: Comparison of three throwing motions

International Journal of Sports Science & Coaching ◽

10.1177/1747954120930370 ◽

2020 ◽

Vol 15 (5-6) ◽

pp. 677-684

Author(s):

Koichi Kawabata ◽

Tatsuya Urata ◽

Koji Fukuda ◽

Satoru Tanabe

Keyword(s):

High Speed ◽

Time Analysis ◽

Release Times ◽

Motion Time ◽

Ball Velocity ◽

Positive Correlations ◽

Throwing Motion ◽

Motion Types

The purpose of this study was to investigate a baseball catcher’s throwing time to second base using three throwing motion types. The subjects were professional ( n = 4) and college ( n = 12) baseball catchers. Two high-speed cameras were set to capture the throwing motion, while one was set to capture the net on second base. The throwing time of quick throw (throwing motion to release the ball immediately after catching the ball rather than usual throwing motion) was significantly shorter than those of usual throw (throwing motion used during games and practice) and fast ball throw (throwing motion to increase the ball velocity than usual throwing motion). From this result, it became clear that quick throw is the optimal throwing motion when judged by time. Thus, with respect to correlations between variables, there were significant positive correlations between throwing and motion times (usual throw: r = 0.760; fast ball throw: r = 0.719; quick throw: r = 0.767), and between throwing and airborne times (usual throw: r = 0.784; fast ball throw: r = 0.744; quick throw: r = 0.806), for all three throwing motions. However, negative correlations were shown between throwing and release times in usual throw and fast ball throw. The results suggest that, to shorten the throwing time, it is necessary to shorten the hold and stride times and to improve the ability to throw the ball as fast as possible with a shorter motion time.

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Analyzing Out-of-Plane Vibration of a Rotating Ring with Wave Propagation

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.693.31 ◽

2016 ◽

Vol 693 ◽

pp. 31-36

Author(s):

Di Shan Huang ◽

Hong He

Keyword(s):

Wave Propagation ◽

High Speed ◽

Harmonic Wave ◽

Roller Bearing ◽

Torsional Motion ◽

Plane Vibration ◽

Coupled Equations ◽

Wave Solutions ◽

Thin Ring ◽

Out Of Plane

Wave propagation is introduced to analyze out-of-plane vibration problem of a rotating ring. Harmonic wave solutions are found for the coupled equations of the axial and torsional motion. Wavenumber spectra and phase velocity map are obtained, and the ratio of axial displacement to torsional displacement and the cut-off frequencies are determined. Examples for the free vibration of the uniform rotating thin ring are given to illustrate the validity of the wave propagation. This research will be valuable in the application of a solid cage in high speed roller bearing.

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Centrifuge Simulation of Wave Propagation due to Vertical Vibration on Shallow Foundations and Vibration Attenuation Countermeasures

Journal of Vibration and Control ◽

10.1177/1077546305054150 ◽

2005 ◽

Vol 11 (6) ◽

pp. 781-800 ◽

Cited By ~ 18

Author(s):

K. Itoh ◽

X. Zeng ◽

M. Koda ◽

O. Murata ◽

O. Kusakabe

Keyword(s):

Wave Propagation ◽

High Speed ◽

Ground Vibration ◽

Vertical Vibration ◽

Shallow Foundations ◽

Testing System ◽

High Speed Trains ◽

Railway System ◽

Environmental Consideration ◽

The Impact

When constructing a high-speed railway system in an urban area, the reduction of the ground vibration and noise generated by train passages is a vitally important environmental consideration. In this paper we focus on the development of a centrifuge vibration testing system, which can simulate dynamic loading acting on shallow foundations. The system is used to generate vertical vibration similar to that generated by high-speed trains. The characteristics of wave propagation in a shallow circular foundation on sand are investigated. The effects of two types of barriers on vibration reduction are studied. Additionally, the impact of using vibration attenuating materials to build trackbeds is evaluated.

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Experimental Contribution to the Modeling of Shock Propagation Induced by a Linear Pyrotechnical Source

Journal of the IEST ◽

10.17764/jiet.51.1.axr1237j54476706 ◽

2008 ◽

Vol 51 (1) ◽

pp. 122-145 ◽

Cited By ~ 1

Author(s):

Christelle Collet ◽

Philippe Chabin ◽

Henri Grzeskowiak

Keyword(s):

Shock Wave ◽

Wave Propagation ◽

High Speed ◽

Composite Plates ◽

Shock Wave Propagation ◽

Shock Propagation ◽

Mechanical Responses ◽

Space Agency ◽

Out Of Plane ◽

Space Launcher

In recent years, the phenomena occurring during shock wave propagation in spatial structures have been studied to characterize more accurately and to minimize the effects of pyrotechnical sources. As part of a program managed by the Centre National d'Etudes Spatiales (CNES, the French space agency), SNPE Matériaux Energétiques (SME) and MBDA France collaborated in a study to understand the mechanisms of shock wave propagation induced by the detonation of a linear pyrotechnical source. The focus of the study was on structures representative of space launcher structures such as those used for the Ariane 5 launcher. Various experiments were performed with metallic and composite plates, and two types of measurement devices (strain gauges and accelerometers) were investigated. Additional out-of-plane velocity and displacement measurements were provided by laser vibrometers, and displays of the separation of the plates were provided by a high-speed camera (up to 4800 feet/second). Signals treatment provided bending and compression strain describing plate mechanical responses. The apparatus used and the associated concerns that arose during the firings also are discussed.

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On High Speed Photoelastie Analysis of Stress wave Propagation

The Journal of the Japan Society of Aeronautical Engineering ◽

10.2322/jjsass1969.21.146 ◽

1973 ◽

Vol 21 (230) ◽

pp. 146-153

Author(s):

Kozo KAWATA ◽

Shozo HASHIMOTO

Keyword(s):

Wave Propagation ◽

Stress Wave ◽

High Speed ◽

Stress Wave Propagation

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High Frequency Signal Propagation in Through Silicon Vias

International Symposium on Microelectronics ◽

10.4071/isom-2012-tp12 ◽

2012 ◽

Vol 2012 (1) ◽

pp. 000239-000243

Author(s):

Srinidhi Raghavan Narasimhan ◽

A. Ege Engin

Keyword(s):

Wave Propagation ◽

High Frequency ◽

High Speed ◽

Signal Propagation ◽

Successful Implementation ◽

High Frequency Signal ◽

3D Ic ◽

Through Silicon Vias ◽

Integration Technology ◽

Silicon Vias

The 3D IC integration technology and silicon interposers rely on through silicon vias (TSVs) for vertical interconnections. Hence, the medium carrying high frequency signals is lossy silicon (Si). Fundamental understanding of wave propagation through TSVs is essential for successful implementation of 3D IC integration technology as well as for the development of Si interposers at RF/microwave frequencies. The focus of this paper is characterization and modelling of TSVs and Si to explore high speed signal propagation through the lossy Si medium. To understand better the physical significance of the TSV, we will establish a framework for wave propagation through TSVs based on dielectric quasi-TEM, skin effect, and slow-wave modes similar to MIS micro-strip lines. For validation of the existence of these modes, full wave simulation results will be compared with simpler two dimensional transmission line simulators.

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