FRP Power Transmission Shaft Tube With Predetermined Axial Weak Point
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Solution Overview
Problem
Conventional power transmission shafts made of fiber reinforced plastic face increased manufacturing costs due to the need for precise dimensioning of connection portions and the formation of multiple layers, which complicates the process of ensuring a weak portion fails under predetermined impact loads.
Innovation Solution
A tubular body for power transmission shafts with a main body portion, a connection portion, and an inclined portion where a weak portion is strategically formed to fail under axial load, reducing the need for precise joining force settings and facilitating cost-effective molding, with options for either decreasing or increasing outer diameter in the inclined portion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
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, increasing manufacturing cost
Solution Approach 1:
The weak portion is pre-formed in the inclined portion during the molding process, creating a predetermined failure point before the product is put into service. This preliminary action ensures that under impact load, the failure occurs at the intended location without requiring precise control of joining forces between separate components.
Solution Approach 2:
The inclined portion is designed with non-uniform wall thickness, creating a localized weak portion with specifically reduced strength in a particular region. This local quality change allows the shaft to fail in a controlled manner at the weak portion while maintaining strength in other areas during normal operation.
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 absorb impact energy, but the peripheral wall portion must be formed of multiple layers, increasing manufacturing cost
Solution Approach 1:
The wall thickness parameter of the inclined portion is varied to create a weak portion, transitioning from a uniform thick-walled structure to a non-uniform structure with localized thin sections. This parameter change enables controlled failure under impact load without requiring multiple material layers.
Solution Approach 2:
The weak portion is pre-formed during the molding process by controlling the wall thickness distribution in the inclined portion. This preliminary creation of a failure point eliminates the need for complex multi-layer structures that would otherwise be required to achieve controlled peeling failure.
3Reliability
If the connection portion and shaft portion are accurately dimensioned to control sliding under impact load, then the power transmission shaft can reliably absorb impact energy, but the manufacturing cost increases
Solution Approach 1:
The inclined portion is designed with locally varied wall thickness, creating a weak portion in a specific region. This local quality differentiation allows the component to be molded as a single piece with controlled failure characteristics, eliminating the need for accurate dimensioning and assembly of multiple precision components.
Solution Approach 2:
The connection portion and shaft portion are merged into a single molded component with an integrated inclined portion. The weak portion is formed as part of this unified structure, combining what would otherwise be separate precision-machined parts into one molded piece, thereby reducing manufacturing complexity and cost.
Data Source
AI summary
A tube is used in fiber-reinforced plastic power transmission shaft. The tube comprises: a cylindrical body section; a connection portion that has a larger diameter than the body section; and an inclined portion that has an outer diameter that increases toward the second connection section from the main body part. The inclined section has formed thereon, a weak section that is damaged when a load input in the axial direction exceeds a prescribed value. With this configuration, the cost of the tube can be reduced, and when a prescribed load is input to the tube in the axial direction, the tube is reliably damaged.