Interlocking Composite Layer Assemblies for Impact Damage Tolerance
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Solution Overview
Problem
Composite materials produced by automated fibre/tow placement are sensitive to damage from low-speed impact, leading to strength reduction and potential catastrophic failure due to the low out-of-plane strength of the matrix between layers, which increases weight and cost when attempting to compensate for this sensitivity.
Innovation Solution
A method of creating composite materials with interlocking layer assemblies made from strips of longitudinal fibres and a binder, where each layer assembly comprises multiple sets of parallel strips deposited at different angles, forming a regular pattern that enhances damage resistance and tolerance without increasing structural weight, by redistributing impact energy and preventing delamination growth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If through-the-thickness reinforcement is provided (e.g., stitching, weaving, braiding), then damage tolerance is improved, but weight and cost increase
Solution Approach 1:
The composite structure is divided into multiple layers with fibers oriented in different directions (0°, 45°, 90°, -45°). Each layer segment handles specific stress components, and the collective arrangement provides through-the-thickness reinforcement without requiring additional reinforcement elements like stitching or weaving. This segmentation of functional responsibilities achieves damage tolerance while avoiding extra weight.
Solution Approach 2:
The invention uses a composite structure combining multiple fiber layers with different orientations and a matrix material. The multi-layer composite arrangement itself provides the through-the-thickness reinforcement function, eliminating the need for separate reinforcement elements. The composite material structure inherently delivers both in-plane strength and out-of-plane damage tolerance without additional weight penalty.
2Strength
If thicker composite material is used to compensate for strength reduction, then strength is improved, but weight increases
Solution Approach 1:
Fibers are oriented at specific angles (0°, 45°, 90°, -45°) at different locations within the laminate to match local stress distributions. This local optimization ensures that each region receives fiber reinforcement precisely where needed to handle specific load paths, maximizing strength efficiency without requiring uniform thickness increases throughout the entire structure.
Solution Approach 2:
The invention introduces fiber orientation in multiple dimensions (different angles and directions) to handle out-of-plane loads. By distributing fibers across multiple angular orientations rather than simply increasing thickness in one dimension, the structure achieves enhanced strength and damage tolerance while maintaining optimal weight-to-strength ratio.
3Reliability
If more material is added to account for strength reduction due to damage, then reliability is improved, but cost increases
Solution Approach 1:
The laminate structure is designed in advance with multiple fiber orientations and a matrix that provides inherent damage tolerance. By pre-configuring the composite structure with this multi-layer arrangement, the need for additional material to compensate for potential damage is eliminated. The preliminary design incorporates the reinforcement function directly into the base structure, avoiding the need for extra material additions later.
Data Source
AI summary
A method is presented for making a composite material from strips comprising longitudinal fibers and a binder or resin, which material comprises a number of layer assemblies one on top of the other. Each layer assembly comprises m sets (with m at least 2) of parallel strips each extending in a different direction, Each layer assembly is manufactured by successive steps of depositing groups of parallel strips according to a well defined pattern (without longitudinally interweaving strips with previously deposited strips). Before completing a layer assembly, with the exception of the last layer assembly, by depositing its last group of parallel strips, the first group of parallel strips of the following layer assembly is already deposited. A composite material manufactured with such a method is presented too.