Composite Shell Assembly Device with Tensioned Shaft
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Solution Overview
Problem
The assembly of composite shell elements with existing methods is challenging due to poor resistance to burring stresses, requiring tight shape tolerances and pre-assembled fasteners, which is time-consuming and difficult to achieve, especially for large-sized structures, and results in parasitic bending stresses.
Innovation Solution
A device comprising cylindrical flanged receptacles with apertures and a shaft under tension, allowing assembly without turned-out edges, with interference fitting and a deformable sleeve to absorb alignment defects, enabling assembly from one side and reducing parasitic stresses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional assembly methods with collars and fasteners are used, then the assembly can transmit force flow, but the contact surfaces must be perfectly adjusted with tight shape tolerances and pre-assembled fasteners, which is time-consuming and difficult to achieve
Solution Approach 1:
The invention extracts and eliminates the collar component from the assembly system. Instead of using a separate collar to join shell elements, the patent integrates the joining function directly into the shell elements themselves through recesses and protrusions, thereby removing the need for pre-assembled fasteners and tight shape tolerances on contact surfaces.
Solution Approach 2:
The invention introduces an intermediary deformable sleeve that fits between the protrusion and the recess. This sleeve absorbs alignment defects and facilitates the assembly process by allowing slight misalignments without requiring perfect adjustment of contact surfaces, thereby reducing assembly time while maintaining reliable force flow transmission.
2Ease of manufacture
If traditional assembly methods with collars are used, then the assembly structure is established, but turned-out edges must be created at extremities which generate parasitic bending stresses
Solution Approach 1:
The invention removes the turned-out edges that were previously necessary for collar-based assemblies. By eliminating the collar and using direct protrusion-recess connections, the method avoids creating the parasitic bending stresses that arise from turned-out edges, while still establishing a valid assembly structure.
Solution Approach 2:
The invention converts the potential harm of rigid connections into a benefit by introducing the deformable sleeve. This sleeve allows controlled deformation that absorbs stress concentrations, transforming what would be harmful stress points into beneficial stress-dissipating features that eliminate parasitic bending stresses.
3Reliability
If composite shell elements are assembled with traditional methods, then the assembly can be made, but the poor resistance to burring stresses requires tight shape tolerances and pre-assembled fasteners
Solution Approach 1:
The deformable sleeve acts as an intermediary that compensates for the poor burring resistance of composite materials. By allowing the sleeve to deform and absorb misalignments, the system maintains assembly integrity without requiring tight shape tolerances on the composite shell elements themselves.
Solution Approach 2:
The invention changes the mechanical parameters of the assembly system by introducing a deformable component. This allows the assembly to accommodate variations in shape and alignment that would otherwise be unacceptable in rigid composite-to-composite connections, thereby maintaining reliability without demanding high manufacturing precision.
4Strength
If local reinforcement of composite shell elements is performed to increase thickness near assembly plane, then resistance to burring improves, but the elements become considerably more rigid and difficult to adapt in shape and perimeter
Solution Approach 1:
The invention extracts the need for local reinforcement by changing the assembly mechanism. Instead of reinforcing the shell elements to resist burring, the patent uses a deformable sleeve that absorbs misalignment stresses, thereby maintaining shape adaptability without requiring increased thickness or rigidity in the composite elements.
Solution Approach 2:
The deformable sleeve serves as an intermediary that protects the composite shell elements from burring stresses during assembly. This allows the elements to remain thin and adaptable in shape while still achieving reliable connections, as the sleeve absorbs the mechanical stresses that would otherwise require reinforcement.
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 efficient assembly of composite shell elements with reduced parasitic stresses and alignment defects, allowing for a Meccano-type mounting without play, suitable for large-sized structures and maintaining structural integrity.
Implementation Method 1
a shaft (40) which can be introduced into said apertures and which is under tension
Implementation Method 2
bearing means (51, 52) which bear on the interior surfaces of the cylindrical receptacles (31, 32) and are able to maintain tension in the shaft (40)
Implementation Method 3
a deformable sleeve to absorb alignment defects
Data Source
AI summary
A device and method for assembling two structural elements made from a composite material is provided. The device includes two cylindrical flanged receptacles, each pierced by an aperture perpendicular to the axis of the cylinder, and a shaft that can be introduced into said apertures. The device also includes bearing means, which bear on the interior surfaces of the cylindrical receptacles and can maintain tension in the shaft when the shaft extends through the apertures in the two receptacles. The device includes means of placing the shaft under tension.