Experimental Testing and Computational Modal Analysis of Air-Inflated Drop-Stitch Fabric Structures for Marine Applications
Abstract
The U. S. Navy seeks to develop the capability to rapidly deploy marine structures. Surface-based inflatable structures including rigid inflatable boats, inflatable causeways and bridging, and launch and recovery systems provide unique solutions for temporary structures used during sea-based missions. Specifically, the Navy seeks to develop inflatable structures using shapes other than the typical cylindrical beams, arches, and spheres that are in service today. Air-inflated drop-stitch fabric panels enable the formation of lightweight inflatable structures that are suitable for structural applications requiring flat shapes. Unlike conventional metallic structures that buckle and fracture when they are exposed to overloaded conditions, air-inflated structures provide a failsafe mechanism during overload conditions: they wrinkle and collapse without damage to the fabric and regain their design shape and structural performance when the overload is removed. Design standards, however, are virtually nonexistent for inflatable structures involving shapes constructed of spheres, beams, arches, and most recently flat panels using three-dimensional woven drop-stitch panels. Predictive performance tools (analytical and numerical) for static and dynamic applications lag behind those for conventional structures, particularly with respect to the influence of inflation pressure on dynamic response. This research establishes the validity of physics-based models using the Ideal Gas Law as an equation of state to predict the natural frequencies and corresponding mode shapes of air-inflated drop-stitch fabric panels as functions of inflation pressure ranging from 5.0 to 30.0 psig. Both numerical and experimental methods were pursued; the results of laboratory modal experiments were used to validate the numerical models. Predicted and experimental natural frequencies and mode shapes were compared, and excellent correlation was observed.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 05, 2017
- Accession Number
- AD1148352
Entities
People
- Andrew W. Hulton
- Christopher J. Hart
- Paul V. Cavallaro
Organizations
- Naval Undersea Warfare Center