gravity), weight, body hardness and dynamic inertia. It is inversely proportional to
string
25 kg for each single one), the hardness of the string flat, manageability and control
knitting and tensioning (when knitted strings are pre-tensioned in the range of
Tennis balls are standard and have a weight
of 0.060 kg. Their external diameter
is between 65 and 68-mm average and this varies throughout the game as it is
reduced as a result of the wear on the external fibre surface. Various designs and
makes of materials of balls are available but the standard professional ball is hollow
inside, rubber cover and fibre textile surf
test rig is the bouncing feature (damping coefficient) when hitting a solid or elastic
ace. Especially important to the design of the
surface [6]. This coefficient is not a constant value and varies
contact surface, speed and material of the ball, etc. within a wide range – between
0.35 and 0.75.
8.2 Experimental data for the bending o
applied external load.
The simplest possible preliminary experimental test was carried out to establish
f the body of the tennis racket under
and clarify some of the basic parameters of the rackets and ball.
From all values measured and set in Table 1 and Table 2 we drew up the graphs
in Figures 1 and 2 underneath showing the relation P/Δ. – Force/deformation. It can be
seen from there that this relation is a linear function regardless of the relatively
complicated shape (elonga
ted ellipse) of the racket [9].
Deformation Δ mm Force P (N) Deformation Δ mm
