Needling Head Shift for Uniform Fiber Layer Bonding
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Solution Overview
Problem
The mechanical properties of composite material parts formed by needling are limited by the uniformity and efficiency of the needling process, which can damage the fiber layer and hinder matrix introduction.
Innovation Solution
A method involving a first needling step followed by a shift step, where the fiber layer is moved relative to the needling head to prevent needles from re-entering previous holes, and a second needling step, improving uniformity and reducing shear, thereby enhancing mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the fiber layer is needled multiple times by the needling head, then the bonding between fiber layers is improved, but the fiber layer is damaged and the uniformity of needling deteriorates
Solution Approach 1:
The invention introduces a shift step between first and second needling steps, where the fiber layer is shifted relative to the needling head along a shift direction. This dynamic repositioning ensures that during the second needling step, needles penetrate into different regions of the fiber layer, creating a more uniform distribution of needling points and avoiding concentration of damage in the same areas while maintaining bonding effectiveness.
2Ease of manufacture
If the needles penetrate into the same holes during needling, then the needling process is simplified, but the fiber layer is damaged and matrix introduction is hindered
Solution Approach 1:
The invention performs a shift step as a preliminary action between the first and second needling steps. This shift repositions the fiber layer relative to the needling head before the second needling operation, ensuring that needles will penetrate into different regions rather than the same holes. This preliminary repositioning prevents fiber damage and creates favorable conditions for subsequent matrix introduction without complicating the overall needling process.
3Ease of operation
If the fiber layer is stationary during needling, then the operation is simpler, but shear in the fiber layer increases and mechanical properties deteriorate
Solution Approach 1:
The invention introduces a shift step where the fiber layer is shifted relative to the needling head along a shift direction between the first and second needling steps. This dynamic repositioning reduces shear in the fiber layer during needling operations, thereby improving the mechanical properties of the final part while maintaining operational simplicity through the structured sequence of steps.
Data Source
AI summary
A method of needling a fiber layer, includes first needling the fiber layer by a needling head, during which the fiber layer is caused to move in translation relative to the needling head, wherein needles of the needling head are distributed uniformly over a surface of the needling head; after the first needling, shifting the fiber layer relative to the needling head along a shift direction through a distance d equal to N·x·p, where N is an integer not less than 1, x is a coefficient greater than 0, and less than 1, and p designates the pitch of two consecutive needles of the needling head along the shift direction; and second needling the fiber layer, after the shifting, and during which the fiber layer is moved in translation relative to the needling head, the needles not penetrating, during the second needling, into the holes formed during the first needling.