FRP Power Transmission Shaft Weak-Point Structure for Impact Failure
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Solution Overview
Problem
Conventional power transmission shafts made of fiber reinforced plastic face challenges in manufacturing cost and weight due to the need for precise dimensions and multiple layers, which are not effectively addressed by existing designs that rely on sliding or peeling mechanisms under impact loads.
Innovation Solution
A tubular power transmission shaft with a weak portion featuring a linear rupture design on its outer surface, made of carbon fiber reinforced plastic, which fails when an axial load exceeds a predetermined value, allowing for cost reduction and weight optimization without requiring precise joining forces or additional members.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the shaft portion slides relative to the connection portion under impact load, then the power transmission shaft can absorb impact energy, but the joining force between the connection portion and the shaft portion must be accurately set, requiring precise molding and increasing the diameter of the connection portion, which leads to increased manufacturing cost and weight
Solution Approach 1:
The patent pre-forms a weak portion with a specific cross-sectional area in the connection portion before the impact occurs. This weak portion is deliberately designed to have lower strength than the shaft portion, so it will fail first under impact load. By performing this structural preparation in advance, the invention eliminates the need for precise joining force control and accurate molding of the connection portion, while still enabling impact energy absorption through the controlled failure of the weak portion.
2Reliability
If the inner peripheral portion of the connection portion peels off together with the shaft portion under impact load, then the power transmission shaft can fail safely, but the peripheral wall portion must be formed of multiple layers, which increases manufacturing cost
Solution Approach 1:
The patent applies local quality by creating a weak portion with specifically reduced cross-sectional area at a localized region of the connection portion, while the rest of the connection portion maintains its normal multi-layer structure. This localized modification allows the weak portion to fail first under impact load, achieving safe failure, while avoiding the need to manufacture the entire connection portion with complex multi-layer structures, thereby reducing manufacturing cost.
3Strength
If the diameter of the connection portion is increased to ensure accurate joining force, then the power transmission shaft can maintain structural integrity, but the weight of the power transmission shaft increases
Solution Approach 1:
The patent creates a weak portion with reduced cross-sectional area at a specific location in the connection portion, while the rest of the connection portion and shaft portion maintain their original dimensions and strength. This localized structural modification ensures that the weak portion fails first under impact load, protecting the main structural integrity without requiring an overall increase in the diameter of the connection portion, thereby avoiding additional weight.
4Ease of manufacture
If a weak portion with reduced cross-sectional area is formed in the connection portion, then the power transmission shaft can fail at a predetermined load with lower manufacturing cost and weight, but the weak portion must be precisely positioned and sized to ensure controlled failure
Solution Approach 1:
The patent pre-forms the weak portion with a specifically reduced cross-sectional area in the connection portion during the manufacturing process. This weak portion is deliberately designed with controlled dimensions and positioning to ensure it will fail first under impact load. By performing this structural preparation in advance with defined geometry, the invention achieves controlled failure at predetermined load while using standard manufacturing processes, avoiding the need for post-manufacturing adjustments or extremely precise assembly.
Data Source
AI summary
A tubular body of a power transmission shaft made of fiber-reinforced plastic is provided with a cylindrical main body portion, and a second connection portion continuous with an end portion of the main body portion and to which a stab shaft is joined. The main body portion is formed with a weak portion which fails when a load input in the direction of an axial line exceeds a predetermined value. A linear rupture portion is formed on an outer peripheral surface of the weak portion. In the present configuration, cost reduction and weight reduction of the tubular body are made possible, and the tubular body fails infallibly when a predetermined load is input to the tubular body in the direction of the axial line.