Composite Hardware Riveting with Variable-Diameter Sleeve
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Solution Overview
Problem
The existing rivet technologies, such as solid, semi-tubular, and blind rivets, face challenges in providing adequate fatigue resistance, avoiding delamination, optimizing shear and tensile resistance, and reducing installation costs when fixing composite materials, with solid rivets causing damage and semi-tubular rivets lacking equivalent fatigue resistance, while blind rivets are costly.
Innovation Solution
A riveting process using a sleeve with a hollow core of varying diameters and an insert without axial bearing surfaces, allowing radial swelling and deformation to form a bulb without countersinking, enabling efficient assembly with conventional tools and ensuring fatigue and shear strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If solid rivets are used for fixing composite materials, then low manufacturing cost is achieved, but delamination occurs due to high radial stresses at the hole edge
Solution Approach 1:
The rivet is divided into two separate components: a tubular sleeve that forms the bulb and an insert that provides structural support. This segmentation allows the insert to occupy the hole and prevent radial stress concentration at the hole edge, eliminating delamination while maintaining the cost-effectiveness of the riveting process
Solution Approach 2:
The insert acts as an intermediary element between the sleeve and the composite material. It occupies the hole and distributes the radial stresses, preventing the high stress concentration that would otherwise occur at the hole edge and cause delamination
2Ease of operation
If semi-tubular rivets are used to reduce installation effort, then easier bulb formation is achieved, but fatigue resistance is insufficient
Solution Approach 1:
The invention merges the advantages of semi-tubular rivets (easy bulb formation) with the advantages of solid rivets (high fatigue resistance) by combining a deformable sleeve for bulb formation with a rigid insert that provides fatigue-resistant structural support throughout the rivet assembly
3Reliability
If blind rivets with crimping are used to achieve good fatigue resistance, then fatigue strength is improved, but manufacturing and installation costs increase significantly
Solution Approach 1:
The invention uses a simple tubular sleeve that can be easily deformed and discarded after forming the bulb, replacing the need for expensive blind rivets and specialized crimping tools. The sleeve performs its function and is then deformed to form the bulb, providing cost-effective fatigue-resistant joining
4Ease of manufacture
If solid rivets are used to ensure low cost, then manufacturing cost is reduced, but countersinking is required on the rivet side
Solution Approach 1:
Instead of countersinking the hole to accommodate a solid rivet head, the invention inverts the approach by using a tubular sleeve that forms its bulb on the opposite side of the composite material. This eliminates the need for countersinking while maintaining low manufacturing costs
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 method combines the advantages of solid and semi-tubular rivets, providing enhanced fatigue and shear resistance, minimizing damage to composite materials, and reducing costs by eliminating the need for countersinking and using traditional riveting machines.
Implementation Method 1
whose diameter is suitable for allowing it to be accommodated without deformation in the first section of the hollow core and capable of enabling it to be forcefully accommodated in the second section, of introducing the insert axially into the sleeve so that the latter swells radially inside the hole
Implementation Method 2
The insert has no axial surface having the function of deforming the sleeve which, in its axial movement inside the sleeve, makes it possible to see only radial deformations
Implementation Method 3
to be ensured by means of a rivet, pressure at the end to be deformed of the sleeve on its first section to ass ure bending by centrifugal radial extension
Implementation Method 4
pressure at the end to be deformed of the sleeve on its first section to ass ure bending by centrifugal radial extension
Implementation Method 5
continuing the folding until the folded end is crimped on the insert, which contributes to the creation of a structural fixing with optimized resistance to tearing
Data Source
AI summary
The invention relates to a method for assembling parts (P1 and P2) in composite hardware by means of a riveting member (R), and is notable in that it comprises: using a bushing (200), the hollow core (230) of which has two different sections (231 and 232); using an insert (100) having no functional axial bearing surface for the radial swelling of the bushing (200) in the through-hole (T), but the diameter (D3) of which is capable of enabling the housing thereof, with no change in shape, in the first section (231) of the hollow core (230), and is also capable of enabling the forcible housing thereof in the second section (232); axially feeding the insert (100) into the bushing (200) such that the latter radially swells inside the through-hole (T) up to the small section (232) thereof and such that the recess well-defined by said small section is occupied by said insert (100); and ensuring, by means of a rivet set (400), the pressure on the first section (231) of the bushing (200) by the end that changes shape to ensure the bending thereof by radial centrifugal extension.