Sculptured Rivet and Deformable Washer for Composite Joints
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Solution Overview
Problem
Traditional mechanical joining systems, such as rivet joints, are not suitable for composite materials as they cause abrasion and fatigue, leading to unsightly and structurally weak connections, particularly in industrial applications like motor vehicle production.
Innovation Solution
A rivet connection system featuring a rivet with a sculptured stem and a washer that undergoes axial deformation to increase contact area, distributing axial compression and reducing the risk of material failure and abrasion, while ensuring structural strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional mechanical rivet joining is used, then connection strength is achieved, but material abrasion and fatigue damage occur
Solution Approach 1:
The patent introduces a specially designed rivet with a sculptured stem surface as an intermediary element. The sculptured surface features micro-structures that act as a mediator between the rivet and the composite material, distributing contact pressures and preventing direct abrasive interaction. This resolves the contradiction by maintaining connection strength through the rivet while eliminating material abrasion through the sculptured surface design.
Solution Approach 2:
The patent changes the surface parameters of the rivet stem by creating a sculptured surface with specific micro-geometric features. This parameter change transforms the smooth surface into a textured surface that can control stress distribution, reduce contact pressure, and prevent material fatigue. The sculptured surface parameters are optimized to balance connection strength with material protection.
2Stability of the object's composition
If rivet closing operation is performed, then joint fastening is achieved, but surface abrasion and unsightly effects are caused
Solution Approach 1:
The sculptured stem surface acts as an intermediary that prevents direct contact and abrasion between the rivet and the composite material during the closing operation. The micro-structures on the sculptured surface distribute the closing forces uniformly, preventing localized stress concentrations that would cause surface damage or unsightly effects while still achieving secure joint fastening.
Solution Approach 2:
The sculptured surface design provides beforehand cushioning by creating a compliant interface between the rigid rivet and the composite material. The micro-geometric features of the sculptured surface absorb and distribute closing forces before they can cause damage, preventing surface abrasion and unsightly effects during the rivet closing operation.
3Ease of manufacture
If conventional rivet design is used, then manufacturing simplicity is maintained, but material damage risk increases
Solution Approach 1:
The patent modifies the rivet stem surface parameters by adding a sculptured texture through conventional manufacturing processes. This parameter change can be achieved through standard techniques such as knurling, rolling, or stamping, maintaining manufacturing simplicity while significantly reducing material damage risk. The sculptured surface parameters are designed to be compatible with existing manufacturing capabilities.
Solution Approach 2:
The patent applies local quality by creating a sculptured surface only on the stem portion of the rivet that contacts the composite material, while keeping other parts of the rivet simple and conventional. This localized modification maintains overall manufacturing simplicity while providing the necessary protection against material damage at the critical contact interface.
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
The system effectively prevents material damage and ensures structural integrity by distributing axial forces over a larger area, reducing the risk of failure and abrasion, making it suitable for industrial use.
Implementation Method 1
bringing about axial deformation of the washer (104) from an undeformed condition in which it fits on the stem (108) with play, to a deformed condition in which it fits on the stem (108) in a condition of interference
Implementation Method 2
The stem (108) is provided as a hollow body that includes a central blind cavity (109) and is to be housed within a seat provided on the washer (104). Like the stem (8), the stem (108) comprises an outer surface (110) that presents a surface sculpturing preferably throughout its extension
Data Source
Figure 1~2A
Figure 3~4A
AI summary
Described herein is a connection system (1; 100) for connection of two or more overlapping layers (L1, L2) of material, the system comprising: - a rivet (2; 102) including a head (6; 106) and a stem (8; 108), the head (6; 106) of the rivet (2; 102) being configured, in use, to bear upon a surface of a first layer (L1) of said two or more layers of material, the stem (8; 108) having an outer surface that comprises a surface sculpturing and being configured, in use, for passing through said two or more layers of material (L1, L1) and projecting beyond them; and - a washer (4; 104) configured to fit (11; 111) on said stem (8; 108) and configured to bear, in use, upon a surface of a last layer (L2) of said two or more overlapping layers (L1, L2) of material, said washer (4; 104) being deformable by axial compression from an undeformed condition where it fits on said stem (8; 108) with play, to a deformed condition where it fits on said stem (8; 108) in a condition of interference with said outer surface of the stem (108). Moreover described is a corresponding method for joining two or more overlapping layers (L1, L2) of material using the aforesaid connection system (1; 100) .