Composite Strut Manufacturing with Slotted Bore for Mandrel Removal
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Solution Overview
Problem
Aerospace struts formed from composite materials often have weakened fused portions at the connections, which can lead to structural failures under tension and compression loads, limiting their rigidity and reliability.
Innovation Solution
A method of fabricating struts with a hollow central bore using a mandrel and filament or fiber material, where slots are formed in the connective end sections to allow bending and enlargement of the bore, enabling the mandrel's removal and resulting in a continuous, unfused central section with enhanced structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If composite materials are used to form aerospace struts, then weight is reduced, but structural strength and reliability are weakened due to fused portions at connections
Solution Approach 1:
The manufacturing process segments the filament laying into distinct sections: continuous filaments in the central section and separate filament ends in the end sections. This segmentation prevents fused portions from forming in the critical central section while allowing end sections to be properly formed and connected to the airframe.
Solution Approach 2:
Different filament configurations are applied to different sections of the strut: the central section uses substantially continuous filaments for maximum strength, while the end sections use filaments that can be properly fused and connected. This local differentiation optimizes both weight and structural integrity in each specific region.
2Ease of manufacture
If slots are formed and connective sections are bent to enlarge the bore, then the mandrel can be removed, but the manufacturing process becomes more complex
Solution Approach 1:
Slots are pre-formed in the end sections before the filament winding process begins. This preliminary action creates predetermined pathways that guide the bending operation and mandrel removal, simplifying what would otherwise be a complex extraction process.
Solution Approach 2:
The end sections are separated from the central section through slot formation and bending, creating distinct segments. This segmentation allows the mandrel to be removed through the enlarged bore openings without disturbing the continuous filaments in the central section.
Data Source
AI summary
A method of fabricating a strut having a hollow central bore includes the steps of providing a mandrel and a quantity of a filament or fiber material, laying the filament or fiber material about the mandrel to form a strut having a central cylindrical section, two opposing connective end sections, a central bore extending through the strut, the central bore having two reduced diameter portions extending through each end section, and an axis extending centrally through the bore, forming a slot or slots extending inwardly from one of the connective section outer ends and terminating within the connective section or the central section, bending at least a portion of the one connective section along the slot to enlarge the bore reduced diameter section at the one end, and displacing the mandrel along the central axis and through the enlarged bore end section until the mandrel is removed from the bore.