Asymmetrical Ultrasonic Joining Element for Porous Materials
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Solution Overview
Problem
The existing methods for joining objects using thermoplastic dowel-shaped joining elements with mechanical vibration are limited in strength and applicability, as the vibration energy asymmetry between the proximal and distal ends of the joining element often results in unsatisfactory anchorage, particularly due to differences in vibration transmission and material properties.
Innovation Solution
The solution involves designing the joining element and recess with asymmetrical features, such as differing end designs, materials, or resistance properties, to balance the vibration energy and improve coupling, allowing for more effective infiltration of thermoplastic material into the porous objects, thereby enhancing the mechanical strength of the joint across a wider range of applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a symmetrical joining element is used in blind holes of two objects, then the joining method is simple to implement, but the vibration energy asymmetry results in unsatisfactory anchorage strength at one end
Solution Approach 1:
The joining element is designed with asymmetrical features where one end has a first configuration (e.g., larger diameter, different material composition, or modified surface properties) and the other end has a second configuration. This asymmetry compensates for the vibration energy distribution differences during ultrasonic joining, ensuring both ends achieve satisfactory anchorage strength in the respective blind holes.
Solution Approach 2:
Different portions of the joining element are given different properties: one end may have enhanced material composition, surface treatment, or geometric features optimized for the specific loading conditions and vibration energy levels at that location, while the other end has properties optimized for its local conditions.
2Length of stationary object
If the joining element length corresponds to the total depth of two blind holes, then the gap between objects is minimized, but the vibration energy transmission is insufficient for proper anchorage
Solution Approach 1:
The asymmetrical design of the joining element ends allows optimization of vibration energy transmission. One end may have a configuration that enhances energy coupling with the sonotrode, while the other end is optimized for anchorage in the second blind hole, ensuring sufficient energy transmission throughout the element length.
3Ease of manufacture
If conventional symmetrical joining elements are used, then manufacturing is straightforward, but the method lacks applicability to various object configurations and materials
Solution Approach 1:
The asymmetrical joining element design provides adaptability to different object configurations, material types, and blind hole geometries. By having different end configurations, the element can be optimized for specific application requirements while maintaining manufacturability through standard formation processes.
Solution Approach 2:
The joining element parameters (material composition, diameter, surface properties) are varied at different ends to adapt to different object materials and configurations, expanding the method's applicability while maintaining ease of manufacture through controlled parameter variations.
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 approach enables the creation of joints with balanced anchorage strength at both ends, improving the overall mechanical strength and applicability of the joining method, allowing for more general and effective use in various applications.
Implementation Method 1
application of mechanical vibration, e.g. ultrasonic vibration
Implementation Method 2
positioning it in a blind hole provided in the object or by forcing it through the surface of the object and by then applying mechanical vibration (e.g. ultrasonic vibration) to the joining element
Implementation Method 3
in its liquid state is pressed into the pores of the porous material where it forms an anchorage on re-solidification. In the anchorage area, the porous material is interpenetrated by the thermoplastic material
Implementation Method 4
in its liquid state is pressed into the pores of the porous material where it forms an anchorage on re-solidification
Data Source
AI summary
A first and a second object (1 and 2) are joined with the aid of a joining element (8) including at least in the region of its distal and proximal ends (8.1 and 8.2) a thermoplastic material. Two blind holes (5 and 6) facing each other are provided in the two objects (1 and 2) and the joining element (8) is positioned in the blind holes such that its distal and proximal ends (8.1) are in contact with the bottom faces of the blind holes and such that there is a gap (9) between the two objects (1 and 2). This assembly is then positioned between a support (3) and a sonotrode (4). The sonotrode (4) and the support (3) are forced towards each other, while the sonotrode (4) is vibrated, thereby liquefying at least part of the material having thermoplastic properties, there, where the joining element ends (8.1 and 8.2) are pressed against the bottom faces of the holes (5 and 6) and allowing the liquefied material to infiltrate into pores of the hole surfaces or unevennesses or openings provided in the hole surfaces.