Composite Barrel Winding Angles Match Thermal Expansion
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Solution Overview
Problem
Composite gun barrels face issues with burst strength, thermal management, and thermal stress due to mismatched coefficients of thermal expansion between the steel inner liner and the carbon fiber composite outer shell, leading to potential deformation and accuracy degradation.
Innovation Solution
A composite projectile barrel design with a continuous fiber composite outer shell that matches the axial coefficient of thermal expansion of the inner liner, achieved by varying the winding angles and thickness of regions around the barrel, ensuring superior axial and torsional strength while minimizing weight and radial bulk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If additional layers of windings are added to improve burst strength and axial strength, then the barrel's strength and stiffness are improved, but the manufacturing complexity, material expense, weight, and barrel profile bulk increase
Solution Approach 1:
The patent applies parameter changes by varying the winding angles of carbon fiber tows at different radial regions of the barrel. The inner region uses a first winding angle, intermediate regions use intermediate winding angles, and the outer region uses a second winding angle. This gradient approach optimizes burst strength and axial strength while minimizing the number of layers required, thereby reducing manufacturing complexity and material expense.
Solution Approach 2:
The patent implements local quality by assigning different winding angles to different radial regions of the barrel. The inner region, intermediate regions, and outer region each have optimized winding angles tailored to their specific structural requirements. This localized optimization allows the barrel to achieve maximum strength with minimal material, reducing overall weight and manufacturing complexity while maintaining superior burst strength.
2Weight of moving object
If carbon fiber composite outer shell is used to reduce weight, then the barrel weight is reduced, but thermal management becomes problematic due to poor heat conduction
Solution Approach 1:
The patent employs composite materials by combining carbon fiber tows with a polymer resin matrix to create a carbon fiber reinforced polymer composite outer shell. This composite structure provides both weight reduction and improved thermal management, as the composite architecture allows for optimized heat dissipation pathways while maintaining the lightweight advantage of carbon fiber.
Solution Approach 2:
The patent addresses thermal management through parameter changes in the composite structure, utilizing the anisotropic thermal properties of carbon fiber composites. By optimizing fiber orientation and layering in different radial regions, the design enhances heat conduction in critical directions while maintaining weight reduction, effectively managing thermal characteristics through structural parameter optimization.
3Weight of moving object
If carbon fiber composite outer shell with mismatched CTE is used, then weight is reduced, but thermal stress and deformation occur during operation
Solution Approach 1:
The patent resolves thermal expansion mismatch through parameter changes in the winding angle configuration. By varying the winding angles across different radial regions, the design optimizes the effective coefficient of thermal expansion of the composite shell to match that of the steel liner. This gradient winding angle approach minimizes thermal stress and prevents deformation during operation while maintaining the weight advantage of carbon fiber composites.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design provides a lightweight, durable barrel that maintains structural integrity under heat, reduces interlaminar stress, and enhances accuracy by matching thermal expansion coefficients, resulting in improved performance and durability.
Implementation Method 1
the average effective axial coefficient of thermal expansion (CTE) of the CFC is approximately equal to the axial CTE of the inner liner
Data Source
AI summary
A composite projectile barrel is disclosed comprising a continuous fiber composite outer shell whose average effective coefficient of thermal expansion in the longitudinal direction approximately matches that of an inner liner. In one embodiment, the composite barrel comprises PAN precursor carbon fiber and a thermoset epoxy resin, with the carbon fiber wound at varying winding angles to form a plurality of regions within the outer shell. The finished barrel exhibits light weight, superior axial stiffness and strength, durability, and is reliably accurate.