FRP Drive Shaft Joint Strength via Segmented Press-Fit Collar
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Solution Overview
Problem
Existing FRP drive shafts face challenges in achieving high joint strength between the FRP cylinder and metal end joints, with previous solutions experiencing stress concentration, heat damage, and peeling phenomena leading to breakage.
Innovation Solution
The implementation of a press-fitting joint with a serrated portion and a cylindrical outer collar, featuring non-circular engaging portions, which are engaged to transfer rotation and distribute torque evenly across the FRP cylinder, preventing peeling and enhancing joint strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If radial through-members are used to join the FRP cylinder and end joints, then the joint structure is simplified, but stress concentrates on the radial penetrations causing the FRP cylinder or through-members to fracture
Solution Approach 1:
The end joint is divided into two separate components: a press-fitting joint inserted into the FRP cylinder and an outer collar fitted on the outer periphery. This segmentation allows torque to be transferred through two distinct regions (inner and outer), preventing stress concentration at single penetration points while maintaining structural simplicity
Solution Approach 2:
The solution transitions from single-dimensional radial stress transfer to two-dimensional torque transfer by utilizing both the inner region (press-fitting joint) and outer region (outer collar) simultaneously. This dimensional expansion distributes stress across multiple pathways, preventing fracture
2Strength
If metal yoke and outer collar are welded together, then joint strength is increased, but the FRP cylinder is damaged by heat
Solution Approach 1:
The press-fitting joint with serrated portions acts as an intermediary mechanical connection between the inner structure and the outer collar. This intermediary enables torque transfer through friction and mechanical engagement without requiring thermal welding, thus protecting the FRP cylinder from heat damage while achieving strong joint connection
Solution Approach 2:
The solution replaces the thermal welding process with a mechanical connection system consisting of press-fitted serrated joints and friction-based torque transfer. This substitution eliminates harmful thermal effects on the FRP cylinder while maintaining or enhancing joint strength through mechanical engagement
3Power
If intermediate cylindrical member with serration-engagement and spline-engagement is used, then torque transfer is improved, but the FRP cylinder itself is damaged
Solution Approach 1:
The serrated portions are localized to specific regions of the press-fitting joint, creating local mechanical engagement points rather than requiring continuous serration along the entire cylinder. This localized approach provides effective torque transfer while minimizing damage concentration on the FRP cylinder structure
Solution Approach 2:
The end joint combines different material properties and engagement mechanisms (press-fitted metal joint with serrated portions, friction-based torque transfer, and outer collar) to create a composite connection system. This composite structure distributes torque transfer across multiple interfaces, preventing damage to the FRP cylinder while maintaining high torque transfer capability
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
This configuration effectively transfers rotational torque to both the inside and outside of the FRP cylinder, preventing breakage due to load differences and preventing peeling damage in multilayered CFRP cylinders, thereby achieving a high transfer torque and increased joint strength.
Implementation Method 1
a press-fitting joint 30 having a serrated portion 31 which is press-fitted into the FRP cylinder 10
Implementation Method 2
non-circular engaging portions which are engaged with each other to transfer rotation
Implementation Method 3
non-circular engaging portions which are engaged with each other to transfer rotation
Implementation Method 4
a rotational torque is exerted simultaneously on both the inside and the outside of the FRP cylinder
Data Source
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AI summary
An FRP drive shaft is achieved in which the joint strength between the FRP cylinder and the metal joint fixed at each end thereof can be enhanced, thereby capable of achieving a high transfer torque. The FRP drive shaft, according to the present invention, is formed by joining metal end-joints to each end of an FRP cylinder, wherein each of the metal end-joints includes a press-fitting joint having a serrated portion which is press-fitted into the FRP cylinder, and a cylindrical outer collar which is fixed to an outer periphery of the FRP cylinder, and non-circular engaging portions which are engaged with each other to transfer rotation are formed on the press-fitting joint and the cylindrical outer collar, respectively.