Definition of feel-related impact parameters of tennis rackets and correlations with racket properties

Abstract Understanding the human–equipment interaction is an important aspect of sports equipment design and engineering. Players are known to describe how the equipment they use feels based on their individualized sensory perception, but this response can be difficult to quantify. For tennis rackets, we have defined two impact parameters proposed as possibly related to player perception of impact “feel” of the racket. Shock Ratio is a measure of the initial impulsive force transmitted to the frame immediately following impact. Nervousness is a measure of the post-impact lingering vibrations. These impact “feel” variables and four other racket properties were measured at twenty-three string-bed locations for ten test rackets using experimental modal analysis. Parameters were monitored and calculated with a custom-built graphical user interface and a repeatability assessment was performed to ascertain the reliability of these measures. The “feel parameters” were then correlated with other racket properties using Spearman’s Rank Correlation Coefficient. The Shock Ratio proxy for minimum vibration load was significantly different across string bed locations revealing significant differences in the areas of minimum Shock Ratio across rackets. There was a moderate but significant correlation ( $$-$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mo>-</mml:mo> </mml:math> 0.53) between damping ratio of the first mode and Nervousness. This correlation should be a focus of future research investigating potential associations with player perception of racket feel and biomechanical responses during strokes. There was also a weak positive correlation (0.31) between Oscillation Ratio (stiffness/damping) and Nervousness highlighting that high stiffness and low damping may be related to frame vibrations players may be sensitive to.