When a player swings the racket to strike the ball, force is first transmitted through the arm to the frame and then distributed across the string bed (the area where the strings intersect). Upon contact with the tennis ball, the strings deform-compressing and stretching-to store energy like a spring. They then snap back rapidly, transferring that energy back to the ball and propelling it at high speed.
The frame plays a role of "support and regulation" in this process. It must be rigid enough to minimize energy loss while retaining sufficient elasticity to dampen vibration and enhance rebound efficiency. The frame's shape and material influence this energy transfer; for instance, a stiffer frame typically offers greater control, whereas a more flexible frame facilitates higher ball speed.
String pattern density and tension also affect performance. A dense pattern (e.g., 18×20) offers greater stability and control, while an open pattern (e.g., 16×19) creates more "bite" on the ball, generating increased spin. Higher tension allows for finer control but reduces elasticity; lower tension makes it easier to generate power but sacrifices precision.
In short, the working principle of a tennis racket is: kinetic energy from the player → transmission via the frame → energy storage and rebound in the strings → acceleration of the ball-all while structural design balances power and spin.