Jonathan J. Miles

The Effect of Asymmetric Mechanical and Thermal Loading on Membrane Wrinkling

Effect of Asymmetric Mechanical and Thermal Loading on Membrane WrinklingJoseph R. Blandino*James Madison UniversityJohn D. Johnston**NASA Goddard Spaceflight CenterJonathan J. Miles*.**James Madison UniversityUrmil K. Dharamsi ....James Madison UniversityAbstractLarge, tensioned membranes are being considered forfuture gossamer spacecraft systems. Examples includesunshields, solar sails, and membrane optics. In manycases a relatively flat membrane with minimal _wrinkling is desired. Developing methods to predictand measure membrane wrinkling is important to thefuture development of gossamer spacecraft. Numericaland experimental data are presented for a 0.5 m square,tensioned membrane. The membrane is subjected tosymmetric and asymmetric mechanical loading. Dataare also presented for a symmetrically loadedmembrane subjected to spot heating in the center. Thenumerical model shows good agreement with theexperiment for wrinkle angle data. There is alsoreasonable agreement for the wrinkled area for bothisothermal and elevated temperature tests.IntroductionMembrane structures typically exhibit nonlinearbehavior when loaded. Since a membrane structurecannot support compressive stresses, local buckling orwrinkling often occurs. At ambient temperature thewrinkle pattern is dependent upon both the membraneand loading geometry. At elevated temperature thewrinkle pattem may also be a function of the materialproperties and the residual stress state of the membrane.The coefficient of thermal expansion will cause thematerial to expand, while heating may relieve any.residual stress from the membrane that was createdduring manufacturing. Quantifying the wrinklingbehavior of a membrane poses many challenges, bothexperimentally and analytically. Th e purpose of thispaper is to present both experimental and computationaldata quantifying the wrinkling behavior of a squaremembrane subjected to symmetric and asymmetricmechanical loading as well as non-uniform thermalloading.

Thermographic identification of wetted insulation on pipelines in the arctic oilfields

Steel pipes used at Alaskan oil-producing facilities to transport production crude, gas, and injection water between well house and drill site manifold building, and along cross-country lines to and from central processing facilities, must be insulated in order to protect against the severely cold temperatures that are common during the arctic winter. A problem inherent with this system is that the sealed joints between adjacent layers of the outer wrap will over time degrade and can allow water to breach the system and migrate into and through the insulation. The moisture can ultimately interact with the steel pipe and trigger external corrosion which, if left unchecked, can lead to pipe failure and spillage. A New Technology Evaluation Guideline prepared for ConocoPhillips Alaska, Inc. in 2001 is intended to guide the consideration of new technologies for pipeline inspection in a manner that is safer, faster, and more cost-effective than existing techniques. Infrared thermography (IRT) was identified as promising for identification of wetted insulation regions given that it offers the means to scan a large area quickly from a safe distance, and measure the temperature field associated with that area. However, it was also recognized that there are limiting factors associated with an IRT-based approach including instrument sensitivity, cost, portability, functionality in hostile (arctic) environments, and training required for proper interpretation of data. A methodology was developed and tested in the field that provides a technique to conduct large-scale screening for wetted regions along insulated pipelines. The results of predictive modeling analysis and testing demonstrate the feasibility under certain condition of identifying wetted insulation areas. The results of the study and recommendations for implementation are described.

Evaluation of microbolometer-based thermography for gossamer space structures

In August 2003, NASAs In-Space Propulsion Program contracted with our team to develop a prototype on-board Optical Diagnostics System (ODS) for solar sail flight tests. The ODS is intended to monitor sail deployment as well as structural and thermal behavior, and to validate computational models for use in designing future solar sail missions. This paper focuses on the thermography aspects of the ODS. A thermal model was developed to predict local sail temperature variations as a function of sail tilt to the sun, billow depth, and spectral optical properties of front and back sail surfaces. Temperature variations as small as 0.5 oC can induce significant thermal strains that compare in magnitude to mechanical strains. These thermally induced strains may result in changes in shape and dynamics. The model also gave insight into the range and sensitivity required for in-flight thermal measurements and supported the development of an ABAQUS-coupled thermo-structural model. The paper also discusses three kinds of tests conducted to 1) determine the optical properties of candidate materials; 2) evaluate uncooled microbolometer-type infrared imagers; and 3) operate a prototype imager with the ODS baseline configuration. (Uncooled bolometers are less sensitive than cooled ones, but may be necessary because of restrictive ODS mass and power limits.) The team measured the spectral properties of several coated polymer samples at various angles of incidence. Two commercially available uncooled microbolometer imagers were compared, and it was found that reliable temperature measurements are feasible for both coated and uncoated sides of typical sail membrane materials.

Radiometric imaging of internal boiler components inside a gas-fired commercial boiler

The Electric Power Research Institute and member utilities have sponsored since 1993 the Advanced Leak Detection - Research Evaluation Demonstration (all red) Project. The all red project utilizes an IR thermography system equipped with a high-temperature lens to detect internal boiler deficiencies and measure temperatures. Two high-temperature IR lenses were developed to perform internal boiler investigations. The lenses can operate in an environment that may reach as high as 2500 degrees F. The internal boiler areas and phenomena that are investigated include: tube temperatures, tube leaks, bowed tubes, and restricted flow; flame shape, flame temperature, and flame location; field distribution and identification of gas species. Detection of parameters that may assist with environmental NOx concerns is also desired. The results of the current study of radiative interactions indicate that IR temperature measurements made inside large commercial gas-fired furnaces are feasible, but acquisition of accurate and repeatable data requires special consideration of radiative phenomena. This study comprised three related efforts - an extensive literature survey and analysis of existing data acquired with a high-temperature lens; an experimental study including acquisition and analysis of spectroradiometric data; and the development of techniques to correct IR thermographic data. Concerns regarding default imager temperature-conversion algorithms and reliability of system calibration are also discussed. This paper represent the culmination of investigations that shed new light on the complexity involved in making in-situ measurements of boiler stream tubes with an IR thermography high-temperature lens system.

Development and implementation of thermal signature testing protocol of auxiliary power unit (APU) and diesel tractor

Thermal signature may be one of the defining factors in determining the applicability of fuel cell auxiliary power unit (APU) technology in military applications. Thermal characterization is important for military applications given that identification and detection may be accomplished through observation of its thermal signature. The operating modes and power takeoff operations of a vehicle will likely determine the thermal profile. The objective of our study was to develop and implement a protocol for quantifying the thermal characteristics of a methanol fuel cell and an idling tractor engine under representative characteristic operations. APU thermal characteristics are a special case for which standardized testing procedures do not presently exist. A customized testing protocol was developed and applied that is specific to an APU-equipped vehicle. Initial testing was conducted on the methanol APU-equipped Freightliner tractor using a high-performance radiometric infrared system. The APU profile calls for a series of infrared images to be collected at three different viewing angles and two different elevations under various loads. The diesel engine was studied in a similar fashion using seven different viewing angles and two different elevations. Raw data collected according to the newly developed methodology provided the opportunity for computer analysis and thermal profiling of both the fuel cell and the diesel engine.

Fiber optic infrared measurement system for thermal measurement of a Kapton HN sample

A dual-waveband, fiber-optic/infrared (F-O/IR) temperature measurement system was enhanced with incorporated optical chopping and applied to measure the surface temperature of a coated (aluminized) Kapton HN sample. The F-O/IR system provides a non-contact means for accurate membrane temperature measurement without distorting surface contour. An FTIR spectrometer was used to measure the absorptance and reflectance properties of the Kapton HN sample. A long-wave IR scanner was used to validate and enhance results obtained from the spectrometer and predict temperature dependence of optical properties. Data are presented that demonstrate the feasibility to apply the F-O/IR system for non-contact temperature measurement of highly reflective surfaces at low temperatures.

Analysis of thermal radiation in coal-fired furnaces

Many utilities throughout the United States have added infrared scanning to their arsenal of techniques for inspection and predictive maintenance programs. Commercial infrared scanners are not designed, however, to withstand the searing interiors of boilers, which can exceed 2500 degrees Fahrenheit. Two high-temperature lenses designed to withstand the hostile environment inside a boiler for extended periods of time were developed by the EPRI M&D Center, thus permitting real-time measurement of steam tube temperatures and subsequent analysis of tube condition, inspection of burners, and identification of hot spots. A study was conducted by Sunderland Engineering, Inc. and EPRI M&D in order to characterize the radiative interactions that affect infrared measurements made inside a commercial, coal- fired, water-tube boiler. A comprehensive literature search exploring the existing record of results pertaining to analytical and experimental determination of radiative properties of coal-combustion byproducts was performed. An experimental component intended to provide data for characterization of the optical properties of hot combustion byproducts inside a coal-fired furnace was carried out. The results of the study indicate that hot gases, carbon particles, and fly ash, which together compose the medium inside a boiler, affect to varying degrees the transport of infrared radiation across a furnace. Techniques for improved infrared measurement across a coal-fired furnace are under development.

A model undergraduate research institute for study of emerging non-contact measurement technologies and techniques

The Infrared Development and Thermal Structures Laboratory (IDTSL) is an undergraduate research laboratory in the College of Integrated Science and Technology (CISAT) at James Madison University (JMU) in Harrisonburg, Virginia. During the 1997-98 academic year, Dr. Jonathan Miles established the IDTSL at JMU with the support of a collaborative research grant from the NASA Langley Research Center and with additional support from the College of Integrated Science and Technology at JMU. The IDTSL supports research and development efforts that feature non-contact thermal and mechanical measurements and advance the state of the art. These efforts all entail undergraduate participation intended to significantly enrich their technical education. The IDTSL is funded by major government organizations and the private sector and provides a unique opportunity to undergraduates who wish to participate in projects that push the boundaries of non-contact measurement technologies, and provides a model for effective hands-on, project oriented, student-centered learning that reinforces concepts and skills introduced within the Integrated Science and Technology (ISAT) curriculum. The lab also provides access to advanced topics and emerging measurement technologies; fosters development of teaming and communication skills in an interdisciplinary environment; and avails undergraduates of professional activities including writing papers, presentation at conferences, and participation in summer internships. This paper provides an overview of the Infrared Development and Thermal Structures Laboratory, its functionality, its record of achievements, and the important contribution it has made to the field of non-contact measurement and undergraduate education.

Development and Implementation of a Thermal Signature Testing Protocol for a Fuel Cell Auxiliary Power Unit (APU) on a Diesel Tractor

Thermal signature is one of several factors that will determine the applicability of fuel cell auxiliary power unit (APU) technology to military vehicles. Thermal characterization is important for military applications in particular because it is a common mode of identification and detection. Fuel cell APU thermal characteristics are a unique case for which standardized testing procedures have yet to be established. The objective of our study was to develop and implement a protocol for quantifying the thermal characteristics of a fuel cell-equipped tractor operating under representative load conditions. Initial testing was conducted on a fuel cell APU-equipped Freightliner tractor using a high-performance radiometric infrared system. The testing protocol calls for a series of infrared images of the APU to be collected at three different viewing angles and two different elevations while the APU is under various loads. The diesel engine was studied under similar load conditions using seven different viewing angles and two different elevations. Simulation of various operating modes and power takeoff operations was performed because thermal profile of the fuel cell was expected to vary as a function of load. Thermal analysis of both the methanol-fueled fuel cell and the diesel tractor were conducted using box averaging and line analysis. We found that the APU had a unique, load-varying thermal profile; however, a metal cover significantly filtered radiation resulting in a measurable but not easily identifiable profile.

Dual roles of infrared imaging on a university campus: serving the physical plant while enhancing a technology-based curriculum

The campus of a comprehensive, residential university is in many respects a small city unto itself. All the amenities and services one would expect in a typical community are readily available on a college campus, including residences, athletic and dining facilities, libraries, and stores. A large campus, therefore, requires a reliable energy plant to provide steam, hot water, chilled water, and electricity. James Madison University supports two power plants: a vintage steam plant and a modern resource recovery facility comprising two solid-waste incinerators and two gas-fired units for steam generation, three steam-driven absorption- chilling units, and a single steam-driven generator for peak electricity production. Infrared imaging, as a teaching tool, was introduced in the Program of Integrated Science and Technology at James Madison University in 1997. The Infrared Development and Thermal Testing Laboratory was established at the university later in 1997 with government and industry support, and it is presently equipped with infrared imagers and scanners, single-point detectors, and data-acquisition systems. A study was conducted between 1998 and 1999 to test the economic feasibility of implementing an IR-based predictive maintenance program in the university steam plant. This paper describes the opportunities created at James Madison University to develop IR-based predictive maintenance programs that enhance the operation of the university energy plants; to establish IR-related research and development activities that support government and industry activities; and to enhance a science- and technology-based curriculum by way of unique, IR-based laboratory experiences and demonstrations.