Composite Resistance Welding with Segmented Electrode Portions
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Solution Overview
Problem
Resistance welding of composite materials faces challenges such as size limitations, uneven welds, and overheating due to high voltages required for large or complex geometries, particularly with carbon fibre layers, leading to degradation and impracticality for complex faying surfaces.
Innovation Solution
A method involving conductive elements with electrode portions of lower resistivity, allowing localized spot welding and sequential welding along the length of the contact area, using a conductive element with lower resistivity electrode portions to minimize current leakage and overheating, enabling access from convenient locations and facilitating welding in complex geometries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If high voltage is applied to generate sufficient heat for large welds, then welding capability is improved, but carbon fibre degradation and overheating occur
Solution Approach 1:
The conductive element is divided into multiple electrode portions spaced apart along the length of the contact area. Each electrode portion can be independently activated, allowing the weld to be constructed in segments rather than requiring a single high-voltage application across the entire weld length. This segmentation enables progressive welding from one end to the other, maintaining lower voltages while achieving long welds without carbon fibre degradation.
Solution Approach 2:
Different regions of the conductive element have different electrical resistivities. The electrode portions have lower resistivity than the intermediate sections, creating localized heating zones at the electrode portions while the intermediate sections conduct current with minimal heating. This local quality differentiation allows precise control of heat generation at specific locations, enabling long welds to be constructed by sequentially activating different electrode portions without overheating any single region.
2Manufacturing precision
If high current is applied to ensure proper welding, then weld quality is improved, but uneven heating and current leakage occur
Solution Approach 1:
The conductive element features electrode portions with lower resistivity specifically positioned at the welding zones, while intermediate sections have higher resistivity. This creates localized low-resistance pathways that guide current flow precisely where needed for welding, minimizing current leakage into adjacent regions. The result is uniform heating at each electrode portion without energy loss to surrounding areas, achieving consistent weld quality along the entire contact area.
3Length of moving object
If sequential electrode connection is used to extend weld length, then weld size is improved, but higher currents and prolonged heating are required
Solution Approach 1:
The conductive element is segmented into multiple electrode portions that can be activated in sequence. By spacing these electrode portions along the contact area, the welding process can progress systematically from one end to the other. Each electrode portion completes its welding function quickly due to the localized heating efficiency, allowing the entire long weld to be constructed in a controlled sequence without requiring prolonged heating at each stage.
Solution Approach 2:
The electrical resistivity parameter is varied along the length of the conductive element, with electrode portions having lower resistivity than intermediate sections. This parameter differentiation allows each electrode portion to generate sufficient heat quickly for proper welding, while the higher resistivity intermediate sections minimize energy loss. The result is an efficient sequential welding process that achieves long weld lengths without excessive heating duration.
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
Enables continuous welding of composite articles with minimal overheating, allowing for consistent welds in complex geometries and high aspect ratios without requiring high voltages, and supports non-destructive testing and repair.
Implementation Method 1
Electrodes or electrode portions of the conductive element extend out from between the faying surfaces, and electrical current is applied to the electrodes to generate resistive heating
Data Source
Figure 1~2
Figure 3a~3c
Figure 4a~4f
AI summary
Disclosed is a method of resistance welding between composite articles. A conductive element is provided between faying surfaces, having a plurality of lower resistivity electrode portions spaced apart along the length of the contact area between the composite articles. The electrode portions can be used to spot weld across the electrode portions, and along a longitudinal portion of the conductive element between the electrode portions by application of an electrical current. Also disclosed are apparatus for use in the resistance welding methods and composite articles and structures and elements incorporating the conductive element.