Composite Dome-Cylinder Layup Without Pole Steering Singularities
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Solution Overview
Problem
Current methods for fabricating composite structures with dome and cylindrical portions face challenges such as steering singularities at the poles of the dome, leading to undesirable effects like wrinkling and fiber misalignment.
Innovation Solution
A method involving the use of a mandrel with a rounded end and a cylindrical surface, where dome plies are laid up using a plurality of rosettes and cylindrical plies using an independent layup rosette, forming a transition region by varying the lengths of the plies to create a joint between the dome and cylindrical portions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional single rosette method is used to lay up dome plies, then the fabrication process is simpler, but steering singularities occur at the poles causing wrinkling and fiber misalignment
Solution Approach 1:
The patent divides the dome layup process into multiple segments by using multiple rosettes (at least three) positioned at different angular locations around the dome. Each rosette handles a specific angular sector, eliminating the steering singularity that occurs at the pole when using a single rosette. This segmentation allows continuous fiber placement without the directional conflicts that cause wrinkling and misalignment.
Solution Approach 2:
The patent introduces an intermediary computational model that calculates optimal fiber placement paths for multiple rosettes. This intermediary system processes the geometric constraints and coordinates the movement of each rosette to ensure smooth transitions and eliminate singularities, acting as a mediator between the simple desire for a single rosette and the need for multiple coordinated rosettes.
2Reliability
If dome and cylindrical portions are fabricated separately and joined, then manufacturing flexibility is improved, but joint inconsistencies and structural weaknesses occur
Solution Approach 1:
The patent merges the fabrication of dome and cylindrical portions into a single continuous process. The same automated fiber placement system that lays up the dome plies continues without interruption to lay up the cylindrical plies, creating a seamless transition zone. This eliminates the separate joining operation that causes joint inconsistencies and structural weaknesses.
Solution Approach 2:
The patent performs preliminary planning of the entire structure (dome plus cylinder) as a single integrated component. The fiber placement paths, rosette positions, and ply orientations are all pre-calculated to ensure continuous coverage from the dome apex through the transition zone into the cylindrical portion, preventing any gaps or misalignments at the junction.
3Volume of moving object
If smaller dome diameters are used, then the overall structure size is reduced, but steering singularities become more pronounced causing increased wrinkling
Solution Approach 1:
The patent applies segmentation by using multiple rosettes positioned circumferentially around the small dome, which distributes the fiber placement tasks and eliminates the steering singularity that would otherwise be amplified on a smaller radius dome. Each rosette operates in its own angular sector with reduced steering requirements.
Solution Approach 2:
The patent transitions from a single-point (1D) rosette approach to a multi-point (2D circumferential distribution) rosette arrangement. By distributing rosettes around the dome's circumference, the system adds a circumferential dimension to the layup process, eliminating the radial steering singularity that plagues small-diameter single-rosette approaches.
Data Source
AI summary
A unitary composite structure and methods of forming are presented. A method of laying up a unitary composite structure comprises laying up a plurality of dome plies on a rounded end of a mandrel using a plurality of rosettes; laying up a plurality of cylindrical plies on a cylindrical surface of the mandrel using a layup rosette independent of the plurality of rosettes; and forming a transition region comprising a joint between the plurality of dome plies and the plurality of cylindrical plies by varying lengths of the plurality of dome plies and lengths of the plurality of cylindrical plies.