Concentric Braided Fastener for UHTC Load Distribution
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Solution Overview
Problem
Ultra high temperature ceramic (UHTC) articles are brittle and micro-cracked, making it difficult to effectively distribute loads using structural fasteners due to complex interlaminar stresses not compatible with monolithic ceramics or composite UHTCs, and existing fastener designs fail to adequately transfer loads and torque.
Innovation Solution
A fastening device with a cylindrical shank comprising concentric braided layers of reinforcing fibers at varying angles, coated with adhesive layers to distribute axial and torque loads, featuring a core braid with a highly axial fiber orientation, a mid braid with a 45-degree angle, and an outer braid with a higher angle approaching the helix angle of the threads, along with an outer adhesive layer to enhance inter-laminar shear characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If structural fasteners are used in UHTC articles, then load distribution is attempted, but complex interlaminar stresses cause incompatibility with monolithic ceramics and composite UHTCs
Solution Approach 1:
The fastener is divided into multiple concentric braided layers with different fiber orientations (0°, 45°, 90°) to segment the load distribution function. Each layer handles specific stress components, preventing stress concentration that would occur in monolithic structures.
Solution Approach 2:
The invention uses composite UHTC materials with braided fiber reinforcement instead of monolithic ceramics. The multi-layer braided structure combines different fiber orientations to create a composite material that can handle complex interlaminar stresses while maintaining compatibility with brittle UHTC substrates.
2Device complexity
If conventional fastener designs are used, then simple structure is maintained, but inadequate load and torque transfer occurs
Solution Approach 1:
The fastener employs a nested multi-layer braided structure where inner and outer braided layers are concentrically arranged. Each layer is infused with resin matrix, creating a nested composite structure that enhances load and torque transfer capability while maintaining a relatively simple cylindrical fastener geometry.
Solution Approach 2:
Different braided layers have different fiber orientations (0°, 45°, 90°) tailored to handle specific local stress states. The 0° layer handles axial loads, the 90° layer handles hoop stresses, and the 45° layer handles shear stresses, optimizing local quality for each region of the fastener.
3Ease of manufacture
If single-layer fastener structures are used, then manufacturing is simplified, but interlaminar stress distribution is insufficient
Solution Approach 1:
The braided layers are pre-formed with specific fiber orientations before being assembled into the final fastener structure. This preliminary preparation of layers with optimized orientations allows for better interlaminar stress distribution while maintaining manufacturing feasibility through standardized braiding processes.
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 device effectively transfers axial and torque loads across the fastener, reducing interlaminar stresses and improving structural integrity by optimizing braid angles and adhesive layers, suitable for brittle materials like UHTCs, and capable of handling extreme environments.
Implementation Method 1
The core braid may be coated with an adhesive layer to form a bond resin interface configured to transfer loads from the threads and head radially inward to the core braid and transmit the axial loads axially along the core braid
Implementation Method 2
The concentric braided layers and adhesive layers may be configured to distribute axial loads from the threads radially inward to, and then axially along, a radially innermost core braid of the braid layers
Implementation Method 3
The outer braid layer may include braided reinforcing fibers that may have a braid angle of greater than 45 degrees relative to the fastener axis, and that may have a braid angle in the approximate range of 60 to 85 degrees relative to the fastener axis. The outer braid layer may include braided reinforcing fibers having a braid angle that approaches a helix angle of the thread.
Data Source
AI summary
A fastening device (10) for securing panels together. Threads (16) are formed along an outer circumference of a shank (12) of the fastening device. The shank is coaxially connected to a head (18) configured to be engaged by and to transfer torque loads from a tool to the shank. The shank comprises concentric cylindrical braid layers (20,22,24) that each includes braided reinforcing fibers infiltrated with a resin matrix and adhesive layers (30,31,36) may be disposed between them.