Braided Composite Structure With Conical Mandrel Hole Routing
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Solution Overview
Problem
Existing methods for forming holes in composite structures, such as carbon fibre materials, often weaken the structure by severing fibres, which reduces their strength and ability to transfer forces like torque, especially when holes are drilled after curing.
Innovation Solution
A method involving a mandrel with conical parts and a braiding machine is arranged to prevent fibre tows from intersecting with the vertex of the conical parts during the braiding process, allowing holes to be formed without fibre severance by adjusting variables like the height and angle of the conical parts, and the relative positions of the mandrel and braiding machine.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If holes are formed by drilling or machining after the composite structure is fully formed and cured, then holes can be created for joints and connections, but the strength of the structure is significantly reduced due to fibre severance
Solution Approach 1:
The conical parts are incorporated into the mandrel before the braiding process begins. During braiding, the fibre tows are routed around these conical parts, which automatically create holes in the final composite structure without requiring subsequent drilling or machining. This preliminary arrangement of the mandrel geometry ensures that holes are formed during the primary manufacturing process, eliminating the need for later fibre-severing operations.
Solution Approach 2:
The mandrel is divided into a base part and at least one conical part. The conical part acts as a separate functional element that defines the hole geometry while the base part supports the overall structure. This segmentation allows the hole-forming function to be integrated into the mandrel design without compromising the structural integrity of the composite during manufacturing.
2Reliability
If the braiding machine runs slowly with manual adjustment to avoid fibres laying onto the vertex of the cone, then fibre breakage is avoided, but manufacturing time and labour increase significantly
Solution Approach 1:
The braiding machine and mandrel are pre-configured with specific geometric parameters before production begins. The conical parts are positioned and dimensioned such that during automated braiding, the fibre tows naturally follow paths that clear the vertices of the conical parts. This preliminary setup eliminates the need for slow manual adjustment during operation, maintaining both high manufacturing speed and fibre integrity through automated precise control.
Solution Approach 2:
Specific parameters of the braiding process are optimized to prevent fibre-tow intersection with conical vertices. By carefully selecting and controlling parameters such as the dimensions of the conical parts, their positioning on the mandrel, and the braiding machine's operational parameters, the system achieves automatic avoidance of fibre breakage conditions while maintaining high automated production speed.
3Reliability
If manual intervention is used to move fibre tows away from the vertex of the cone during braiding, then fibre integrity is maintained, but manufacturing cost and complexity increase
Solution Approach 1:
The mandrel design with integrated conical parts enables the braiding process to self-regulate fibre path routing. The geometry of the conical parts automatically guides the fibre tows along safe paths that clear the vertices, eliminating the need for external manual intervention or complex control systems. The system serves itself by using the mandrel's own geometry to prevent fibre breakage conditions.
Solution Approach 2:
The optimal configuration of conical parts on the mandrel is determined in advance through design and modeling. This preliminary design ensures that during automated braiding, the fibre tows naturally follow paths that avoid the conical vertices without requiring real-time manual adjustment or complex active control mechanisms, thereby maintaining simplicity while ensuring fibre integrity.
Data Source
AI summary
A method of manufacturing a composite structure includes providing a mandrel comprising a base part and at least one conical part. The base part comprises an elongate shaft. The base part of the mandrel comprises a cylindrical surface around a longitudinal axis of the base part. The at least one conical part extends from the cylindrical surface of the base part. The mandrel and a braiding machine are moved relative to one another such that fibre tows are braided over at least the base part of the mandrel. The mandrel and the braiding machine are arranged such that during the braiding process, none of the fibre tows intersect with a vertex of the at least one conical part of the mandrel.