Composite Projectile Connecting Element for Impact Stress
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Solution Overview
Problem
The connection between composite material and steel components in piercing military projectiles is inadequate to withstand the stresses encountered during impact, particularly when penetrating thick concrete targets, due to axial compression, bending, and hydrodynamic effects, leading to potential separation and damage.
Innovation Solution
A connecting element with a metal longitudinal extension and annular abutment is used to support the composite material body, providing lateral contact and bonding, which helps in transmitting axial compression and compensating for radial and bending stresses, allowing the composite material to work optimally in axial compression and enhancing mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If composite material is used for the cylindrical body to reduce weight, then weight efficiency improves, but connection strength with steel nose deteriorates under impact stresses
Solution Approach 1:
A connecting element made of steel is introduced as an intermediary component between the composite cylindrical body and the steel nose. This mediator provides a strong mechanical connection that can withstand impact stresses while allowing the composite body to maintain its weight advantages. The connecting element features an annular abutment that contacts the front edge of the composite body and a longitudinal extension that provides lateral support.
Solution Approach 2:
The projectile employs a hybrid construction combining composite material for the cylindrical body with steel components (nose and connecting element). The composite body provides weight reduction while the steel connecting element provides the necessary strength and durability at critical connection points, creating an optimized composite structure that balances weight and strength requirements.
2Ease of manufacture
If steel is used for the nose to provide scratch resistance and ease of machining, then durability and manufacturability improve, but overall projectile weight increases
Solution Approach 1:
Steel is used locally only where required (at the nose and connecting element) to provide scratch resistance and ease of machining, while the majority of the projectile body is made from lighter composite material. This localized application of heavy material minimizes weight increase while maintaining the functional benefits of steel where needed.
Solution Approach 2:
The projectile uses a composite construction with steel nose and connecting element combined with composite cylindrical body. This allows the advantages of steel (scratch resistance, ease of machining) to be preserved at critical components while the overall weight is reduced through the use of composite materials for the main body structure.
3Quantity of substance
If composite material is used for the body to increase explosive mass ratio, then payload capacity improves, but resistance to bending and radial stresses deteriorates
Solution Approach 1:
The steel connecting element acts as a mediator that protects the composite body from bending and radial stresses. It absorbs and distributes these stresses away from the composite material, allowing the composite body to maintain its lightweight, high-explosive-ratio design while the connecting element handles the mechanical stresses that would otherwise compromise the composite structure.
Solution Approach 2:
The connecting element provides enhanced strength locally at the connection zone where bending and radial stresses are most severe, while the composite body maintains its optimized design for maximum explosive capacity. The steel reinforcement is applied precisely where needed to counteract specific stress types without adding unnecessary weight elsewhere.
4Strength
If drilling is used to bond the connecting element to the composite body, then bonding strength improves, but composite fibers are damaged
Solution Approach 1:
The patent replaces mechanical fastening methods (drilling and screwing) with chemical bonding using adhesive. This substitution eliminates the need to drill holes through the composite body, thereby preserving the integrity of the composite fibers while still achieving strong bonding between the connecting element and the composite cylindrical body.
Solution Approach 2:
The bonding method changes from mechanical (drilling) to chemical (adhesive bonding), fundamentally changing the parameter of how the connecting element is attached to the composite body. This parameter change allows for strong bonding without the harmful effects of drilling, maintaining both bonding strength and fiber integrity.
Data Source
AI summary
According to the invention, the rear part of the connecting element (1), which part is intended to be connected to a body (4) made of composite material, comprises at least one abutment (13) of annular shape, centered with respect to a longitudinal axis (10) and intended to come into contact with the front edge (14) of said body (4), and a longitudinal rearward extension (15) which is defined from said abutment (13) onward and which comprises a contact face (16) and has a shape and diameter suited to said body (4) so that its contact face (16) can come laterally into contact with a peripheral surface (17) thereof.