Biomimetic Soft-Bodied UUV Propulsion for Acoustic Stealth
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Solution Overview
Problem
Current underwater vehicles face limitations in speed, range, stealth, and endurance due to noisy and inefficient propulsion mechanisms, suboptimal hydrodynamics, structural impedance mismatch, risk of collision damage, and limited battery energy density.
Innovation Solution
A biomimetic underwater vehicle design utilizing soft robotics and electro-active polymers, replicating the propulsive and hydrodynamic structures of pelagic fishes, with a central chord member and muscle layers featuring dielectric elastomer actuators for efficient, silent, and acoustically transparent propulsion, along with energy recovery systems for enhanced endurance and collision resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If conventional propellers and rotating machinery are used for propulsion, then propulsion force is generated, but noisy tonal noise is produced that makes the UUV easily detected
Solution Approach 1:
The patent replaces conventional rotating mechanical propellers with a biomimetic caudal fin propulsion system that uses oscillating flexural waves. This substitution eliminates the need for rotating machinery and bearings, thereby eliminating the tonal noise generated by conventional propellers while maintaining effective propulsion force through hydrodynamic lift and drag mechanisms.
Solution Approach 2:
The patent changes the propulsion mechanism from high-frequency rotating motion to lower-frequency oscillating flexural waves. This parameter change in motion frequency and pattern reduces the generation of tonal noise while maintaining propulsion effectiveness through the oscillating caudal fin structure that mimics natural fish swimming.
2Strength
If syntactic foam and hollow pressure vessels are used for structural support, then structural strength is improved, but acoustic waves are reflected creating impedance mismatch
Solution Approach 1:
The patent employs a flexible soft-bodied structure composed of elastomeric materials that can deform and adapt to environmental pressures. This flexible shell design replaces rigid hollow pressure vessels, allowing the structure to absorb acoustic waves through deformation rather than reflecting them, thereby achieving acoustic transparency while maintaining structural integrity through material flexibility and energy dissipation.
3Strength
If conventional rigid UUV designs are used, then structural integrity is maintained, but collision damage risk increases in shallow-water environments
Solution Approach 1:
The patent utilizes a soft-bodied flexible structure made of elastomeric materials that can deform upon impact with obstacles. This flexibility allows the UUV to absorb collision energy through material deformation and structural compliance, significantly reducing damage from impacts with the seabed or other objects in shallow-water environments while maintaining overall structural integrity through the cohesive elastomeric construction.
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 biomimetic underwater vehicle achieves high-speed endurance with low self-noise, improved stealth, and increased resistance to collision damage, while offering efficient energy use and expanded operational depth, surpassing conventional UUV capabilities.
Implementation Method 1
Each actuator comprises a standardized actuator cassette, each cassette including a stack of Dielectric Elastomer Actuator (DEA) layers
Implementation Method 2
low-cost organic polymers may be tuned to match the impedance of water, creating an acoustically transparent propulsion system
Data Source
AI summary
An acoustically stealthy, soft-bodied underwater propulsion system includes a central chord member and a series of successive muscle layers each having a skeletal mechanism and a set of actuators. Each skeletal mechanism includes a central vertebra, two or more actuator arms extending radially outward from the central vertebra and disposed axially symmetrically about the central chord member, and an actuator plate extending from a radially outward end of each actuator arm and oriented substantially transverse to the actuator arm. Each actuator is situated between an actuator plate from a first muscle layer of the series and a second muscle layer of the series.