Hybrid Composite Projectile Barrel Locking Features
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Solution Overview
Problem
Hybrid composite firearm barrels face stress concentration and low adhesive strength at the interface between dissimilar materials, leading to potential fracture and corrosion, especially in breech and muzzle transition regions due to thermal and mechanical stresses.
Innovation Solution
Incorporating mechanical locking features such as notches and pins on the inner liner, which interlock with the continuous fiber composite outer layer during manufacturing, to distribute stresses effectively and enhance adhesive strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If adhesive bonding is used to join the inner steel liner to the outer composite layer, then the barrel structure is simplified and manufacturing is easier, but the interface strength is insufficient under thermal and mechanical stresses
Solution Approach 1:
The invention combines adhesive bonding with mechanical locking features (ribs and grooves) to create a hybrid joint system. The adhesive provides continuous bonding while the mechanical features provide stress distribution and interlocking, creating a composite joining system that overcomes the limitations of adhesive alone.
Solution Approach 2:
The interface between the inner liner and outer composite layer is segmented into multiple regions through the addition of ribs and grooves. This segmentation allows stress to be distributed across multiple locations rather than concentrated at a single interface, improving overall joint strength.
2Device complexity
If the interface between dissimilar materials is simplified, then manufacturing is easier and costs are lower, but stress concentration occurs leading to fracture and corrosion
Solution Approach 1:
The interface is segmented into multiple regions using ribs and grooves, which distribute stress across numerous smaller contact points rather than a single continuous interface. This reduces stress concentration at any one location, preventing fracture and corrosion initiation.
Solution Approach 2:
The mechanical locking features (ribs and grooves) are applied locally at the interface regions where stress concentration is most critical, rather than throughout the entire barrel structure. This provides enhanced reliability at critical locations while maintaining simplicity elsewhere.
3Reliability
If thermal expansion differences between composite and steel components are accommodated, then reliability under thermal stress improves, but manufacturing complexity increases
Solution Approach 1:
The interface is divided into multiple segments through ribs and grooves, allowing each segment to accommodate thermal expansion independently. This segmentation enables the structure to handle differential thermal expansion between steel and composite materials without creating excessive stress.
Solution Approach 2:
The mechanical locking features modify the physical parameters of the interface, creating compliance that allows for thermal expansion movement. The ribs and grooves provide a mechanism that accommodates parameter changes (thermal expansion) while maintaining structural integrity.
Data Source
AI summary
An improved hybrid composite projectile barrel comprising an inner liner and an outer composite matrix, the inner liner having a breech transition region and a muzzle transition region. The breech transition region and the muzzle transition region each comprises locking features that secure the outer composite matrix to the inner liner at the transition regions. In a first embodiment, the locking features are a series of longitudinally extending ribs with notches. In a second embodiment, the locking features are a plurality of pins disposed around the circumference of the breech and muzzle transition regions. In a third embodiment, the ridges and pins are combined such that a pin extends from the top of each ridge. In each embodiment with pins, the height of the pins is preferably adjusted so that the top ends of the pins form a line that is parallel with the outer diameter of the inner liner.