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oai:www.ideals.illinois.edu:2142/19087 2023-07-10 col_2142_5131 col_2142_16278 com_2142_5130 com_2142_16277 com_2142_9614

Groppel, J. Shin, In-Sik 2011-05-07T11:56:32Z 2011-05-07T11:56:32Z 10000-01-01 1989 The motion of the ball and frame during and just after impact was inferred from the acceleration-time change of an accelerometer instrumented impactor pendulum, and the strain-time change of the frame during the clamped racket impact. The impulsive loads acting on the elbow joint were estimated by adopting an inverse dynamic analysis (impulse-momentum equation) for the racket and forearm during the backhand drive. The stiffness and string tension conditions tested in the experiment were 5450 and 7540 N/m crossed with 178,245, and 311 N, respectively for the two phases of tests. Generally, the impulse of the first acceleration spike was not consistently affected by the string tension and frame stiffness. However, at the slowest impact speed, high string tension and flexible frame significantly reduced the impulse on the ball. This specific result was partly consistent with the impulse measured in actual backhand drive impact where only the tighter string reduced the impulse applied to the ball. Although the mean impulses produced by the stiff frame were larger than those by flexible frame at the tested string tensions, the difference was not significant. The mean linear and angular impulses acting on the elbow joint during backhand drive were 0.804 N $\cdot$ sec and 0.416 N $\cdot$ sec, respectively, with large variability in the measures. The approximated peak impulsive force and moment was 144 N and 78 Nm respectively. The effect of different string tension and frame stiffness on the impulsive loads at the elbow joint during backhand drive was not significant. Recommendations. A lighter impactor would improve the applicability of the impactor pendulum results to actual racket and ball interaction. A set of 3-D impulse-momentum equations need to be developed for incorporation into 3-D motion analysis. ETDs are only available to UIUC Users without author permission U of I Only AAI9011021 (UMI)AAI9011021 http://hdl.handle.net/2142/19087 eng Copyright 1989 Shin, In-Sik Applied Mechanics Education, Physical Engineering, Biomedical The influences of string tension and frame stiffness on racquet and ball motions, and on impact loads at the elbow joint during the tennis backhand drive text Kinesiology and Community Health Kinesiology University of Illinois at Urbana-Champaign Dissertation Ph.D.