Session: 12-07-01: Mechanics of Soft Materials
Paper Number: 93951
93951 - Soft Artificial Muscle Actuators for Undersea Launch and Recovery Systems
The U.S. Navy’s pursuit of increased autonomy for Undersea Warfare (USW) missions present significant launch, recovery, positioning and control (LRP&C) challenges. Innovative technologies are necessary for LRP&C of USW assets from both legacy and future undersea platforms where manned presence is not possible. Subsea platforms include submarines, UUVs, etc. – each having limited onboard stowage and operational support for LRP&C systems. The need to innovate new actuation technologies is further intensified by increasing demands for rapid deployability with rapid compactability, autonomy, scalability, adaptability and connectivity across the undersea to surface domains.
Inflatable and on-demand deployable/compactable actuator technologies coupled with state-of the-art High Performance Fabrics (HPF) materials and soft robotics can provide transformational and disruptive LRP&C solutions with the enhanced robustness necessary for autonomous missions in extreme underwater environments. In contrast to rigid structures that can yield, permanently deform and fracture during overloading events, inflatable structures provide a fail-safe mechanism in the form of elastic wrinkling where, upon restoration from overloading, inflatable structures fully recover.
The proposed research investigates the mechanical behaviors, load and stroke capacities and limitations of artificial soft fabric muscles (ASFMs) subject to extreme undersea environments for undersea LRP&C of USW assets. Load capacities are not well documented in the literature; however, several papers and patents suggest load capacities as high as 10,000-lbs in tension can be theoretically achieved. The limiting factors on load capacities are the fiber materials, fiber quantities, fabric architectures and actuator fatigue life cycles.
This research considers both short- and long-term operations with air-inflated and water-inflated configurations for USW. Water-inflated ASFMs are necessary to avoid implosion when operating in the submerged environments. Both Finite Element Analysis (FEA) and experimental methods are pursued to evaluate the static, dynamic, cyclic, cold (deep-sea) temperature and hydrostatic behaviors of ASFMs constructed of High Performance Fabrics (HPFs), hyperelastic bladder materials and inflatable soft structures. Performance efficiencies and end closure designs were optimized to achieve maximum force-contraction metrics.
Physics-Based Models of braided ASFMs were generated using MATLAB scripts in conjunction with HyperMesh Finite Element Analysis (FEA) preprocessor. The scripts enabled rapid generation of braided ASFM models necessary for investigating the effects of various fiber materials, fabric architectures, onsets of shear jamming states, actuator length/diameter (L/D) ratios and to permit scalability studies. The ASFM models were run using ABAQUS/Explicit FEA software to: (1) identify and rank key performance parameters (KPPs) such as stroke distance and force capacities, (2) evaluate fabric patterns, braid periodicity factor l and interfiber spacings, (3) short and long term duration response, and (4) develop virtual design criteria and methods for ASFMs. Equations of state (EOS) were used to govern the mechanical and thermodynamic behaviors of the inflation media (gases, liquids) during radial expansion and axial contraction of the ASFMs upon pressurization.
Experimental tests were performed on circular braided ASFMs constructed of different high performance fiber materials having a range of 2.0-inch to 10.0-inch nominal diameter. The tests measured the tensile force-axial contraction behaviors (short and long term durations), shear jamming states and interfiber friction coefficients for each braid. Additional testing included tensile and creep evaluation of individual fiber bundles (yarns). The experimental results identified critical material and system behaviors that the models simulated. Correlation studies were performed between model, analytical and test results.
ASFMs operating in deep-water hydrostatic and hydrodynamic environments present new focus areas not previously considered for artificial soft muscles. This research combined multiple disciplines in the areas of inflatable structures, soft robotics, hydraulics & pneumatics, High Performance Fabrics (HPFs), thermodynamics and nonlinear materials. Capacity thresholds and limitations of ASFMs were identified to advance the technology base for next-generation soft actuators used in USW operations.
Presenting Author: Paul Cavallaro Naval Undersea Warfare Center
Presenting Author Biography: Paul Cavallaro is the Leader of the Mechanics of Advanced Structures and Materials Team (C7023) at the Naval Undersea Warfare Center Division Newport, Newport, RI. He has over 35 years of experience in research, design, finite element analysis and experimental testing of composites, sandwich structures, metals, elastomers and technical textiles. His current research areas include multi-scale computational and experimental mechanics of discrete material systems, interfacial damage mechanics, and development of predictive performance tools for use in advanced structures. His focus areas include innovative applications for lightweight structures, advanced composite pre-forms, composites damage and fracture behaviors, deployable and inflatable structures with Fluid/Structure Interactions, ballistic protection systems, cold spray additive manufacturing of metals, buoyancy recovery systems for undersea applications and inflatable launch and recovery systems for USW towed bodies and vehicles. He has authored more than 45 technical reports, journal publications, conference papers and several book chapters. He holds 18 issued U.S. patents with 5 additional pending related to the state of the art advancement in materials, mechanical testing, composites and technical textiles.
Authors:
Paul Cavallaro Naval Undersea Warfare CenterMichael Smith Naval Undersea Warfare Center Division Newport
Jacob O'donnell Naval Undersea Warfare Center Division Newport
Allison Redington Naval Undersea Warfare Center Division Newport
Eric Warner Naval Undersea Warfare Center Division Newport
Soft Artificial Muscle Actuators for Undersea Launch and Recovery Systems
Paper Type
Technical Paper Publication