Lightweight Tennis Racket Frame with Porous Foam Insert
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Solution Overview
Problem
Existing tennis rackets with fiber reinforced resin frames and foam for enhanced rigidity and vibration absorptivity are heavy, making them difficult to swing quickly.
Innovation Solution
A hollow racket frame with a foam structure that includes an inside, outside, and middle parts, where the foam occupies a portion of the frame with air in the remaining space, providing excellent impact feel while maintaining a lightweight design through specific density and area ratios, and a manufacturing method involving lamination and curing of prepregs with foam pieces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large foam is included to enhance rigidity and vibration absorptivity, then the racket is excellent in feel at impact, but the weight becomes large and players cannot swing the racket quickly
Solution Approach 1:
The patent uses foam material with a porous structure containing numerous bubbles. This porous structure provides both vibration absorptivity and rigidity enhancement while maintaining lightweight properties. The foam's cellular architecture allows it to absorb impact vibrations effectively without adding excessive weight, resolving the contradiction between feel at impact and weight.
Solution Approach 2:
The patent combines foam material with fiber reinforced resin to create a composite structure. The foam is integrated into the frame at specific positions, creating a composite racket that leverages the advantages of both materials: the foam provides vibration absorption and comfort, while the fiber reinforced resin maintains structural strength and lightweight properties.
2Strength
If foam is joined to inner surface of the frame, then the racket maintains structural integrity, but the foam occupies space reducing the hollow structure's weight advantage
Solution Approach 1:
The patent applies foam material locally at specific positions within the frame rather than filling the entire structure. The foam is positioned at locations where it provides maximum vibration absorption and structural support, while leaving other areas hollow to maintain weight advantages. This localized application resolves the contradiction between structural integrity and weight reduction.
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 racket achieves a balance of excellent impact feel and light weight, allowing for easier swinging while maintaining structural integrity and vibration damping properties.
Implementation Method 1
the foam enhances vibration absorptivity of the racket
Implementation Method 2
a foam joined to a part of one of the inner surfaces of the frame and containing bubbles
Implementation Method 3
laminating a foam piece containing a large number of bubbles onto a part of a surface of a prepreg
Implementation Method 4
laminating a foam piece containing a large number of bubbles onto a part of a surface of a prepreg having a matrix resin
Implementation Method 5
curing the matrix resin
Implementation Method 6
curing the epoxy resin included in each prepreg
Data Source
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AI summary
A racket includes a head 8, a first foam 6a and a second foam 6b. The head 8 is formed from a fiber reinforced resin. The head 8 has an inside part 16, an outside part 18 and two middle parts 20. The foams 6 are joined to respective inner surfaces of the middle parts 20. Each foam 6 includes a matrix and a large number of bubbles dispersed in the matrix. In a cross section of the head 8, a ratio of an area of the foam 6 to an area of a space is equal to or greater than 5% and equal to or less than 50%. The foam 6 has a density of equal to or less than 0.30 g/cm3. The foam 6 has a 25%CLD measured in accordance with "JIS K6254" standard of equal to or less than 0.10 MPa.