Eugene Niemi

Sensing performance of electrically conductive fabrics and suspension lines for parachute systems

The electronic sensing capabilities of parachute fabrics and suspension lines coated with conducting polymers, single-walled carbon nanotubes, and their composites are described. A new synthetic method is described to obtain a thin, strongly adhering coating of conducting polymers on commercial parachute fabrics and suspension lines using oligoanilines as an undercoating. The results indicate that both materials have a sensing ability; however, the coated suspension lines show superior performance compared to the coated parachute fabrics.

REVIEW OF SMART MATERIAL TECHNOLOGIES FOR ACTIVE PARACHUTE APPLICATIONS

The performance (drag, lift, stability, etc.) of a parachute is a function of the physical properties of the canopy fabric (such as porosity) and geometry of the canopy (such as air-vent openings). These variables typically remain constant during descent and therefore the parachute retains constant drag and lift. The ability to change these variables and the parachute drag and lift characteristics during flight will greatly widen the performance envelope of a parachute, the maneuverability, and versatility of the airdrop mission. This paper provides a literature review of existing smart material technologies in an effort to improve the performance characteristics and enhance the safety of existing parachutes and parafoils by incorporating these advanced materials into parachute systems.

Sensing performance of electrically conductive fabrics and dielectric electro active polymers for parachutes

This paper quantifies the sensing capabilities of novel smart materials in an effort to improve the performance, better understand the physics, and enhance the safety of parachutes. Based upon a recent review of actuation technologies for parachute applications, it was surmised that the actuators reviewed could not be used to effectively alter the drag or lift (i.e. geometry, porosity, or air vent openings) of a parachute during flight. However, several materials showed potential for sensing applications within a parachute, specifically electrically conductive fabrics and dielectric electro-active polymers. This paper introduces several new conductive fabrics and provides an evaluation of the sensing performance of these smart materials based upon test results using mechanical testing and digital image correlation for comparison.

High-strain and deformation measurements using imaging and smart material sensors

The purpose of this paper is to present experimental testing results obtained by using a novel polymer high strain sensor, Metal RubberTM. Dynamic, quasi-static tensile and quasi-static bending tests are performed to study the sensors change in resistance as a result of the application of various mechanical loads. The strain signal generated by the Metal RubberTM sensor is also compared to the strain measured by a set of optical imaging cameras during a high strain tensile test of a nylon fabric. The results of the aforementioned experiments indicate that the Metal RubberTM sensor exhibits non-linearity and hysteresis as compared to a conventional metal foil strain gage. In addition, time varying, stress hardening was observed in the sensor. Results of the dynamic tests demonstrated that the sensor could be used to determine the resonant frequencies of a cantilever beam, when compared to using an accelerometer or a metal foil strain gage.

Sensing of electrically conductive textiles and capacitance sensor-embedded fabrics for parachutes

This paper evaluates the conductive properties and sensing capabilities of various smart materials being considered for enhancing parachute performance. In a previous review of sensing technologies, several materials showed potential for parachute implementation - specifically, electrically conductive textiles and dielectric electro-active polymers (DEAPs). Past efforts have been focused on mechanically testing and evaluating the sensing performance of conductive fabrics (coated with carbon nanotubes, polypyrrole and polyaniline) and DEAPs. While some of the conductive fabrics demonstrated sufficient sensing capability, they were not conductive enough to implement into an intelligent parachute sensor network for transmitting power or data. Also, attaching or stitching DEAPs to the parachute fabric has proven to be a challenge. The primary goal of this paper is to investigate the use of highly-conductive textiles in an intelligent textile sensor network for sensing and as a means to transmit power or electrical signals. The applications of the materials investigated in this paper may also extend beyond parachutes to any large-scale textile structure.

Introduction of Parachute Aerodynamics into an Undergraduate Aerodynamics Course

This paper describes an aerodynamics course that covers the basics of a typical first course in aerodynamics, but also includes two weeks of coverage of parachute aerodynamics. It is designed to fill a need by providing students with an introduction to parachutes as a resource for local research labs and industry, as well as providing a university’s graduate students with the background to work on ongoing research projects related to parachutes. The procedure described here as to which topics to delete from the basic course, to provide room for the parachute information, can be used to introduce other major topics into an aerodynamics course, such as rotary-wing aerodynamics, supersonic aerodynamics, or orbital mechanics.

Sensing Performance of Electrically Conductive Parachute Fabrics and Suspension Lines

This paper quantifies the sensing capabilities of novel smart materials in an effort to improve the performance, better understand the physics, and enhance the safety of parachutes. Based upon a recent review of actuation technologies for parachute applications, several materials showed potential for sensing applications within a parachute, specifically electrically conductive fabrics and suspension lines. This paper introduces several new electrically conductive fabrics and suspension lines and provides an evaluation of the sensing performance of these smart materials based upon test results using mechanical testing.