Drop Stitch Inflatables - and some random concepts and ideas on growing and casting structured materials

Windy_Skies · June 5, 2021, 6:59pm

I’d like to see a dropstitch loom (in action). I haven’t been able to find that yet. I wonder if looms exist that can make (compound) curves.

Some results searching for “dropstitch”, that might answer some questions:

https://repository.tudelft.nl/islandora/object/uuid:283ee3ae-7a4b-4fb2-a4b5-7b0c44a71d65/datastream/OBJ/download

Recent Advancements in the Development of Inflatable Multi-Hull Boats Utilizing Drop-Stitch Fabric

ABSTRACT
The development and use of drop-stitch technology has been around since the early 1950’s when Goodyear and the U.S. Government began experimenting with inflatable airplanes. In 1991, CDI Marine (then Band Lavis and Associates) conducted a feasibility study for the U.S. Navy to develop a concept design for a 4-meter inflatable combat rubber raiding craft utilizing drop-stitch fabric. The purpose of this project was to determine if drop-stitch technology could be adapted to small inflatable boats to improve their performance, i.e., seakeeping and speed.

Over the past 20 years, the design of inflatable high performance hullforms has expanded to include more sophisticated multi-hull hull forma that, for performance purposes, require rigid appendages of wood and aluminium to be attached to the hulls in order to achieve the proper hull shape. The initial design concerns raised with respect to the rigidity of the attachment points were resolved. Test results bore out the feasibility of such attachments to the degree that specific hard attachments can now be confidently employed in new designs. This development leads the way for future boats that are larger and with more powerful engines. Such past proposals to build large boats with composite after bodies, containing powerful Personal Water Craft (PWC) waterjet propulsion packages, are now within the realm of reality with minimal risk.

KEY WORDS
Inflatable Boats
Drop-Stitch Fabric
Multi-Hull Boats
Advanced Hullform

Starboard Inflatable Woven Technology for Inflatable Paddleboards

https://supinflatables.co.uk/info/board-construction

https://youtu.be/jJiCVw6UCF4?t=363

https://digitalcommons.uri.edu/theses/1856/

Abstract

Drop-stitch inflatable structures are of increasing significance in aerospace, naval, and military applications. The advantages of drop- stitch inflatable structures are high strength to weight ratios, rapid deployment capabilities and ease of storage. The stiffness of the structure increases with inflation pressure and is dependent on the material properties of the panel skin.

The objective of this research was to characterize the constituent material properties and mechanical response of drop-stitch inflatable panels subjected to various load conditions. This research aimed to characterize the nonlinear elastic response of drop-stitch inflatable panels by using a new material system in comparison to previous studies. These characterizations included three dimensional digital image correlation, uniaxial and biaxial loading, and panel inflation and bending experiments.

Material properties of the drop-stitch inflatable panel skin were experimentally determined across multiple experiments utilizing three dimensional-digital image correlation. In addition, three dimensional digital image correlation was used to characterize panel skin surface displacements and strains in a way not done before in previous drop-stitch structure research.

The results of this research found that relevant material properties of the dropstitch inflatable panel were able to be experimentally determined through multiple different experiments, however these material property values are extremely sensitive to load conditions. Further research is required to accurately predict the structural behavior from constituent characterization data.

Recommended Citation

Buglio, Ryan A., “CHARACTERIZATION OF DROP-STITCH CONSTITUENT MATERIALS AND INFLATED PANEL RESPONSE” (2020). Open Access Master’s Theses. Paper 1856.
"CHARACTERIZATION OF DROP-STITCH CONSTITUENT MATERIALS AND INFLATED PAN" by Ryan A. Buglio

Some old results when searching for “airmat” (as used in the Goodyear Inflatoplane):

https://archive.org/download/DTIC_AD0402310/DTIC_AD0402310.pdf

Structural Fabric Program

JO Miller, E BILKSY - 1962 - apps.dtic.mil

A structural fabric investigation, related to aerospace applications, was initiated to provide a means of manufacturing large low-density Airmat structures made of metallic cloth and yarns capable of small volume packaging. The effort included an investigation into the problem of …

…

The purpose of this program, as related to aerospace application, is to provide a means of manufacturing large low-density AIRMAT* structures made of metallic cloth and yarns capable of small volume packaging.

The work reported herein was accomplished during the seventh quarterly period under contract AF33(600)-43036. During this period, the loom design was finalized and fabrication of the major portion of the loom parts and assemblies was completed. The design of the take-off mechanism was completed and fabrication was underway. A site for the loom was selected and preparations are underway for loom installation.

The aforementioned efforts are directed toward the development of a loom procurement specification and the actual procurement of a loom capable of producing a low-density AIRMAT in the order of 20 feet wide with a maximum depth of 8 feet.

https://archive.org/download/DTIC_AD0628050/DTIC_AD0628050.pdf

DTIC AD0628050: INFLATABLE STRUCTURE TEST PROGRAM

Small specimen tests (elevated temperature with internal pressure) were performed to predict the ability of a CS-105 silicone elastomer coated AIRMAT model to withstand the environment of a hypersonic wind tunnel (900- 1500?F). The specimens all leaked badly in the expected wind tunnel temperature range. This indicated the probability of subsequent model failure. The wind tunnel model tests were successful however. Influence coefficient and vibration tests, both at room and elevated temperatures, were performed on AIRMAT models in support of flutter research. As before, the models could not withstand elevated temperature (800?F or above). The laboratory model inflation pressure was 10 psi compared with the wind tunnel model inflation pressure of about 2 psi. Time at temperature and/or an oxidizing atmosphere could be failure factors. Further testing of CS-105 coated AIRMAT structures is needed to evaluate the influence of load, pressure, temperature, and environment on coating characteristics and wire strength.