Multi Clinch Fastener Insert for Composite Panels
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Solution Overview
Problem
Current fastening technologies for composite materials face issues with thread strength, retention force, and stress concentration due to small bearing areas, which are not effectively addressed by existing self-clinching fasteners, especially in brittle materials like carbon fiber and aluminum honeycomb panels.
Innovation Solution
A two-piece fastener system comprising a retainer with a through-hole and knurls, and an insert with multiple self-clinching features of increasing diameters, allowing for secure attachment and accommodating various panel thicknesses and tolerances, using a retainer and insert that can be made from metallic or non-metallic materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If self-clinching fasteners are used in composite panels, then installation speed and simplicity are improved, but the fasteners cannot engage brittle materials like carbon fiber or honeycomb panels
Solution Approach 1:
The fastener is divided into two separate components: a retainer that engages the composite panel and an insert that provides threading. This segmentation allows each component to be optimized for its specific function - the retainer for engaging brittle composite materials without requiring deformation, and the insert for providing secure threading engagement.
Solution Approach 2:
The retainer acts as an intermediary between the composite panel and the threaded insert. It provides a ductile metal interface that can accommodate the insert through deformation, while its knurled exterior engages the composite panel through a hole without requiring the panel material itself to be ductile.
2Ease of operation
If mechanical riveting inserts are used, then self-clinching capability is achieved, but thread strength and retention force are reduced due to material softness requirements
Solution Approach 1:
By separating the clinching function (retainer) from the threading function (insert), the design allows the retainer to be soft enough for deformation while the insert can be made from harder materials with superior thread strength. The retainer's deformation provides the self-clinching effect, while the insert provides the strong threading engagement.
3Device complexity
If small bearing area fasteners are used, then installation is simplified, but stress concentration on the panel increases leading to material failure
Solution Approach 1:
The retainer distributes loads across multiple dimensions: the knurled exterior distributes panel engagement stress around the hole perimeter, while the multiple clinch features distribute the fastening load across several deformation zones within the panel thickness, reducing stress concentration at any single point.
4Strength
If adhesive fastening methods are used, then thread strength is improved, but installation time and complexity increase
Solution Approach 1:
The design replaces the chemical bonding process of adhesives with a mechanical self-clinching process. The insert is forced through the retainer, causing plastic deformation that mechanically locks the components together, eliminating the need for adhesive application and curing time while maintaining strong joint integrity.
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 fastener system provides higher strength joints in composite panels, with improved pull-out strength and simplified installation compared to adhesive methods, enabling secure attachment of multiple layers with reduced material stress and accommodating a range of panel thicknesses and materials.
Implementation Method 1
deformation of a cylindrical through-hole wall by the self-clinching features. Each self-clinching feature comprises a land and an undercut for receiving material of the retainer displaced by the land
Implementation Method 2
The retainer has a head of enlarged diameter and a shank with peripheral gripping means for engaging a wall of the panel hole
Data Source
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AI summary
An insert for the attachment of objects to composite or plastic panels consists of two parts, a retainer and an insert. The retainer has a through-hole and knurls on its perimeter for gripping the walls of a receiving hole in the composite or plastic panel. The insert has multiple self-clinching features at increasing diameters which when inserted into the retainer rigidly attach it to the retainer. The panel is rigidly clamped between opposite sides of the panel by an enlarged head of the retainer and an opposing flange on the insert. The self-clinching features of different diameter permit the device to be used with panels of different thickness and allow a large tolerance range. A plain or threaded stud can be substituted for the threaded hole of the insert. Both the retainer and the insert can be metallic.