Racket Frame Stiffness Layout for Higher Ball Repulsion
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Solution Overview
Problem
Existing tennis rackets do not achieve optimal repulsion performance, as the balance between side pressure stiffness and ball-hitting face stiffness is not adequately addressed, 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 internally, which enhances the bending properties to achieve a large ball-hitting face stiffness while maintaining a small side pressure stiffness.
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 reduces comfort and control
Solution Approach 1:
The patent applies local quality by creating different stiffness characteristics in different directions of the racket frame. Through specific structural design and material arrangement, the ball-hitting face achieves high stiffness for repulsion performance, while the side pressure direction maintains low stiffness for comfort and control. This directional differentiation of mechanical properties directly resolves the contradiction between ball speed and side pressure stiffness.
Solution Approach 2:
The patent employs composite materials with different elastic moduli arranged in specific orientations within the racket frame. By combining materials with varying stiffness characteristics and arranging them in composite layers, the structure achieves high ball-hitting face stiffness while maintaining low side pressure stiffness, thereby resolving the technical contradiction between repulsion performance and comfort.
2Ease of operation
If the side pressure stiffness is decreased to improve comfort and control, then the ball-hitting face stiffness also decreases which reduces repulsion performance
Solution Approach 1:
The patent resolves this contradiction by applying local quality through directional structural design. The frame structure is configured to provide low side pressure stiffness for comfort and control while simultaneously providing high ball-hitting face stiffness for repulsion performance. The localized structural features allow different regions of the frame to have different stiffness characteristics optimized for their specific functions.
Solution Approach 2:
The patent uses composite materials with anisotropic properties to achieve directional stiffness control. By arranging composite material layers with specific fiber orientations and material compositions, the structure achieves low side pressure stiffness for comfort while maintaining high ball-hitting face stiffness for repulsion performance, thereby resolving the contradiction between ease of operation and ball speed.
3Speed
If the frame structure is made more complex to achieve optimal stiffness ratio, then the manufacturing difficulty increases
Solution Approach 1:
The patent applies segmentation by dividing the frame structure into multiple discrete components or modular sections that can be manufactured separately and then assembled. This modular approach reduces the manufacturing complexity of the overall structure while enabling precise control of stiffness characteristics in different regions, thereby resolving the contradiction between performance and ease of manufacture.
Solution Approach 2:
The patent resolves the contradiction by optimizing specific parameters such as material elastic moduli, layer thicknesses, and structural dimensions to achieve the desired stiffness ratio. By carefully selecting and adjusting these parameters within certain ranges, the patent achieves optimal ball speed performance while maintaining manufacturability, avoiding excessive structural complexity.
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 solution effectively enhances the repulsion performance by ensuring a high ball speed upon impact, with the ball-hitting face stiffness being significantly larger than the side pressure stiffness, resulting in improved repulsion performance.
Implementation Method 1
a high-elasticity layer with straight-type reinforcement fibers positioned internally, which enhances the bending properties to achieve a large ball-hitting face stiffness
Data Source
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.