Cold-Sprayed Ductile Powder Assembly for Lightweight Multi-Material Joints
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Solution Overview
Problem
Existing multi-material assembly techniques, such as welding pins and cold spraying, face limitations in mechanical strength, weight increase, and accessibility requirements, making them unsuitable for lightweight vehicle construction, particularly when assembling materials like carbon-fiber composites with steel or aluminum alloys.
Innovation Solution
A 3D metal bump with low density is produced by additive manufacturing on a support surface, featuring a network of micrometric protrusions or holes, which provides optimized shearing resistance and mechanical attachment without the need for pre-existing holes or access to both sides, using cold spraying with textured surfaces to enhance bonding between dissimilar materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If welding pins are used to assemble multi-material components, then mechanical strength and reliability are improved, but weight increases significantly due to iron-based materials
Solution Approach 1:
The invention changes the material parameter from iron-based (density 7.8 g/cm³) to aluminum-based (density 2.7 g/cm³) welding pins, reducing density by approximately 65%. This parameter change maintains the welding function and mechanical strength while significantly reducing the weight of the assembly, directly resolving the contradiction between strength and weight.
Solution Approach 2:
The invention uses composite material structures where aluminum-based pins are employed in hybrid assemblies combining steel and aluminum or composite components. The aluminum-based pin serves as an intermediary that can be resistance-welded to steel while being lighter than traditional iron-based pins, creating a multi-material assembly that optimizes both strength and weight.
2Strength
If welding pins are used to assemble multi-material components, then mechanical strength is improved, but the complexity of the assembly process increases due to multiple requirements
Solution Approach 1:
The aluminum-based welding pin is designed to be universally applicable in multi-material assemblies involving steel, aluminum, and composite materials. It can be resistance-welded to steel components while providing a bonding surface for aluminum or composite parts, eliminating the need for different pin types for different material combinations and simplifying the assembly process.
Solution Approach 2:
The invention specifies pre-defined geometric parameters for the welding pin (cylindrical shape with diameter of 3 to 8 mm and length of 5 to 15 mm) that are optimized for resistance welding. These preliminary design decisions establish universal dimensions that work across different assembly configurations, reducing the need for complex geometric adaptations and simplifying the assembly process.
3Ease of manufacture
If conventional assembly techniques are used, then manufacturing simplicity is maintained, but the ability to assemble dissimilar materials is limited
Solution Approach 1:
The aluminum-based welding pin acts as an intermediary component that bridges dissimilar materials (steel, aluminum, composites) that cannot be directly resistance-welded together. It provides a common interface that can be welded to steel while bonding to other materials, enabling the assembly of multi-material components using conventional resistance welding equipment without requiring new manufacturing techniques.
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
This solution enables flexible, lightweight multi-material assemblies with improved mechanical strength and reduced weight, suitable for automotive and aerospace applications, by creating a dense, mechanically strong agglomeration that adapts to varying geometries and thicknesses, while avoiding the limitations of traditional methods.
Implementation Method 1
This method, which is particularly suited for depositing ductile metallic materials, allows for the formation and cohesion of a coating due to the plastic deformation of the particles and the substrate upon contact with the substrate in the first moments of the growth of the coating
Implementation Method 2
The support surface is prepared in advance by the impact of a laser beam (local melting and sublimation of the material) with a certain energy and frequency so as to generate a micrometric network R of holes
Data Source
AI summary
The present application describes a method for attaching a first part (20) and a second part (30) for mechanical assembly to each other, the method comprising spraying a powder (10) of a ductile material onto the parts (20, 30), causing the parts (20, 30) to become attached to one another by agglomeration of this powder (10), the method comprising texturing at least one surface of one of the two parts (20, 30) onto which the spraying is subsequently carried out.