Racket Head Structure With Localized Stiffness for Ball Repulsion
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Solution Overview
Problem
Existing tennis rackets do not achieve optimal repulsion performance, as measured by the ratio of ball-hitting face stiffness to side pressure stiffness, limiting the speed of the ball upon impact.
Innovation Solution
A racket design with a frame that has a ratio of ball-hitting face stiffness to side pressure stiffness greater than or equal to 3.20, incorporating a high-elasticity layer with straight-type reinforcement fibers positioned on the inner side of the head, enhancing both face and side pressure stiffness values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the ball-hitting face stiffness is increased to improve repulsion performance, then the ball speed increases, but the side pressure stiffness also increases which may reduce comfort and control
Solution Approach 1:
The patent applies different stiffness characteristics to different regions of the racket head. The ball-hitting face is designed with high stiffness (G2) to maximize ball speed, while the side pressure area is designed with lower stiffness (G1) to maintain comfort and control. This is achieved through specific structural design of the frame that creates a large ratio G2/G1 ≥ 3.20, allowing each region to have optimized local properties for its specific function.
2Strength
If the frame structure is modified to achieve higher ball-hitting face stiffness, then repulsion performance improves, but the side pressure characteristics deteriorate
Solution Approach 1:
The frame structure is designed to create localized stiffness differences. The ball-hitting face region incorporates structural features that maximize stiffness (G2) for optimal energy transfer, while the side pressure regions are designed with different structural characteristics that provide lower stiffness (G1) for player comfort and control. The ratio G2/G1 ≥ 3.20 ensures that these local quality differences are sufficiently pronounced to achieve both performance goals simultaneously.
3Power
If the racket design focuses on maximizing kinetic energy transfer, then ball speed increases, but the structural complexity increases
Solution Approach 1:
The patent achieves improved kinetic energy transfer by optimizing key structural parameters of the frame rather than introducing complex mechanisms. By adjusting the ratio of ball-hitting face stiffness (G2) to side pressure stiffness (G1) to be ≥ 3.20, and by optimizing parameters such as frame thickness, material distribution, and geometric dimensions, the design maximizes power transfer efficiency while maintaining a relatively simple overall structure that is manufacturable and practical.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design achieves improved repulsion performance by allowing for higher ball speed upon impact, with the ball-hitting face stiffness value being relatively large and side pressure stiffness value being relatively small, resulting in enhanced kinetic energy transfer.
Implementation Method 1
a high-elasticity layer with straight-type reinforcement fibers positioned on the inner side of the head, enhancing both face and side pressure stiffness values
Data Source
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AI summary
A racket includes a frame 4. The frame 4 includes a head 14. The head 14 includes a first high-elasticity layer 37a and a second high-elasticity layer 37b. Each of these high-elasticity layers 37 is positioned on an inner side in the head 14 in a thickness direction of the head 14. Each high-elasticity layer 37 includes straight-type reinforcement fibers. In the frame 4, a ratio (G2 / G1) of a ball-hitting face stiffness value G2 to a side pressure stiffness value G1 is greater than or equal to 3.20. In the frame 4, a ratio (Tf / Wf) of a thickness Tf of the frame 4 to a width Wf of the frame 4 is preferably greater than or equal to 2.0.