Shoulder-Centered Sleeve Composite Joint for Stress Management
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Solution Overview
Problem
Composite joints, particularly those involving dissimilar materials, are the weakest link in mechanical systems due to stress mismatches, thermal expansion issues, and manufacturing challenges, leading to high stress concentrations, peel stresses, and difficulties in bonding and inspecting large members.
Innovation Solution
A composite joint design featuring a metal first member with a groove, a fiber-reinforced composite second member, and a unitary annular connector member with beveled edges and a radially extending raised portion, which is adhesively bonded to the composite member and received in the groove to bias the load path from the peripheral to the central portion, minimizing peak stresses and optimizing stiffness and thermal expansion matching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a typical mismatched joint bonds two members of different thicknesses and stiffnesses, then the joint can connect dissimilar members, but it creates high stress concentrations at the leading edges and high peel stresses that reduce joint strength
Solution Approach 1:
A compliant layer is introduced between the thick and thin adherents to act as a stress-distributing intermediary. This layer has intermediate stiffness properties that bridge the mismatch between dissimilar members, reducing stress concentrations at the leading edges and minimizing peel stresses while still enabling the joint to connect dissimilar members of different thicknesses and stiffnesses.
2Quantity of substance
If a typical mismatched joint is used to join large members, then the joint can connect large components, but it creates manufacturing problems including adhesive squeeze-out, voids, uncontrolled fillets, and alignment difficulties
Solution Approach 1:
The compliant layer is pre-formed and positioned between the adherents before adhesive application. This preliminary placement establishes controlled geometry and spacing, preventing adhesive squeeze-out and void formation while ensuring consistent fillet profiles. The pre-positioned layer also facilitates alignment of large members during assembly.
3Adaptability or versatility
If a typical mismatched joint is used, then the joint can connect members of different properties, but it creates high stress concentrations that initiate failure and reduce fatigue life
Solution Approach 1:
The compliant layer modifies the stiffness parameter distribution through the joint thickness, creating a gradual transition rather than an abrupt mismatch. This parameter change in the intermediate layer reduces stress concentrations at the leading edges and distributes cyclic loads more evenly, thereby extending fatigue life while maintaining the ability to join members of different properties.
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 design enhances structural strength, fatigue life, and reduces peel stresses by moving load paths into low-stress regions, improving manufacturing consistency and non-destructive inspection capabilities, while maintaining compactness and ease of assembly.
Implementation Method 1
the connector member is adhesively bonded to the composite member
Implementation Method 2
the raised portion received in the groove so as to bias a load path between the first member and the second member from a peripheral portion to a central portion of the connector member
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
A composite joint includes a first member (12) having a groove (14) therein, a second member (16) adjacent to the first member (12), and a connector member (18) disposed between the second member (16) and the first member (12). The connector member (18) is received in the groove (14) so as to bias a load path between the first member and the second member from a peripheral portion to a central portion of the connector member.