Flat Composite Layup Features for Wrinkle-Free 3D Forming
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Solution Overview
Problem
The challenge in composite material manufacturing is forming complex 3D shapes from flat laminates without wrinkles or structural integrity loss, as carbon fiber is resistant to stretching and AFP machines are inefficient when laying up sharp corners, leading to increased machine time and expense.
Innovation Solution
The method involves generating designs for flat laminates with layup features that allow them to be formed into complex 3D shapes without creasing or warping, using a mandrel with features to compensate for constraints and an NC program that adjusts for discrepancies during layup, enabling the formation of '2.5D' laminates that maintain structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If AFP machines lay up complex 3D shapes directly, then the desired 3D geometry is achieved, but the machine speed is substantially reduced and production time increases
Solution Approach 1:
The complex 3D shape is segmented into a flat laminate portion and a forming portion. The flat laminate is laid up at high speed using conventional AFP processes, then separately formed into the final 3D shape. This segmentation allows the majority of the part to be manufactured efficiently while only the necessary contouring operations are performed afterward.
Solution Approach 2:
The flat laminate is prepared in advance with predetermined features (such as varying thickness regions or material properties) that enable subsequent forming into 3D shapes. By preparing the laminate flat first, the AFP machine can operate at optimal speed, and the forming action is deferred to a later stage when speed is less critical.
2Shape
If flat laminates are formed into complex 3D shapes, then complex geometries are achieved, but wrinkles form due to carbon fiber resistance to stretching
Solution Approach 1:
The laminate is designed with locally varying properties: a flat portion with uniform thickness and a forming portion with predetermined non-uniform thickness or material characteristics. This local quality variation allows the forming region to accommodate 3D geometry changes without inducing wrinkles in the overall structure.
Solution Approach 2:
The solution transitions from attempting to form 3D shapes directly during layup to creating a flat 2D laminate with embedded features that enable subsequent 3D forming. This dimensional approach separates the layup process (flat) from the forming process (3D), allowing each to be optimized independently.
3Shape
If AFP machines lay up sharp corners in complex 3D shapes, then complete geometric fidelity is achieved, but machine time and expense are substantially increased
Solution Approach 1:
The part geometry is segmented into regions requiring high geometric fidelity (sharp corners) and regions where flat laminates suffice. The AFP machine lays up the flat portions efficiently, while sharp corners are formed subsequently using forming tools or post-processing operations, reducing overall machine time.
Data Source
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AI summary
Systems and methods are provided for designing flat composites that are formed into 3D shapes. One embodiment is a method that includes loading data defining a three dimensional (3D) shape for a composite part, identifying constraints based on dimensions of the 3D shape, simulating flattening of the 3D shape into a planar shape, and acquiring a mandrel having the planar shape. The method also includes placing features at the mandrel which permit a laminate laid-up onto the mandrel to compensate for the constraints during forming of the laminate into the 3D shape, and generating a Numerical Control (NC) program that directs an Automated Fiber Placement (AFP) machine laying up the laminate. The NC program includes instructions for laying up tows of constituent material onto the mandrel having the features, to form layers of the laminate.