Multi-Clinch Fastener Insert for Composite Panel Clamping
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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, making them unsuitable for brittle materials like carbon fiber and aluminum honeycomb panels, which cannot support installation loads.
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, enabling direct contact clamping between the retainer and insert for enhanced strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If self-clinching fasteners are used in composite panels, then installation speed and joint strength are improved, but the panel material must be ductile metal which excludes brittle materials like carbon fiber
Solution Approach 1:
The fastener is divided into two separate components: a retainer that remains in the panel and an insert that provides the threaded function. This segmentation allows each component to be optimized for different functions - the retainer for mechanical anchoring in brittle materials and the insert for threading operations
Solution Approach 2:
The retainer acts as an intermediary between the brittle panel material and the threaded insert. It provides a ductile interface that can deform during installation while the insert remains intact, enabling self-clinching benefits to be applied to brittle composite materials
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:
Separating the clinching function (retainer) from the threading function (insert) allows each to be optimized independently - the retainer for mechanical anchoring and the insert for high-strength threading without compromising either function
Solution Approach 2:
The insert design incorporates multiple clinch features with varying diameters and geometries that create different deformation zones, allowing the material to be sufficiently soft for installation yet maintain high thread strength through optimized geometry and material distribution
3Strength
If flaring or riveting operations are performed, then mechanical attachment is achieved, but the bearing area is small creating high stress on the panel
Solution Approach 1:
The multiple clinch features are arranged in a stepped configuration along the insert, creating deformation zones at different diameters. This dimensional arrangement distributes the mechanical load across multiple areas rather than concentrating it at a single point, reducing stress on the panel
4Adaptability or versatility
If adhesive fastening is used, then material compatibility with composite panels is improved, but installation time and process complexity increase
Solution Approach 1:
The patent replaces the chemical bonding mechanism of adhesives with a mechanical self-clinching system. The insert is installed using a press that applies mechanical force to deform the retainer and secure the insert, eliminating the need for adhesive application and curing time while maintaining compatibility with composite materials
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 solution provides higher strength joints in composite panels, with improved pull-out strength and faster installation compared to adhesive methods, suitable for a range of materials including carbon fiber and honeycomb panels, by utilizing a retainer and insert that deform to securely clamp the panel between them.
Implementation Method 1
deformation of a cylindrical through-hole wall by the self-clinching features
Implementation Method 2
peripheral gripping means for engaging a wall of the panel hole
Data Source
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.