COMPLIANT STRUCTURES LABORATORY Mechanical Engineering Department
South Dakota School of Mines and Technology, Rapid City, South Dakota
The Compliant Structures Laboratory (CSL) is dedicated to promoting engineering based on compliance, or flexibility, as is found in naturally occurring biological structures. Dr. Christopher H. M. Jenkins founded the CSL in 1993 to provide computational and experimental facilities to understand and predict the performance of these challenging structures. Since that time, CSL has been directly involved in research supporting a variety of private sector corporations and governmental organizations such as the Air Force Office of Scientific Research, the Army Research Office, the Jet Propulsion Laboratory, NASA, the National Science Foundation, and the Naval Research Laboratory. Numerous MS and Ph.D. students have trained in the lab.
Some examples of our capabilities and recent activities include:
General Analysis
Deployment Modeling
Shape Control
Active Polymers for Shape Control of Inflated Reflectors
Membrane Dynamics
Additional Analysis
Current Research Assistants
Current Research
Mechanics and Materials in Structural Design
Publications
Solar Neutrino Detector Experiment
Facilities at Compliant Structure Laboratory
Forthcoming Book
A New Book on Gossamer Spacecraft
Edited by:
Dr. Christopher H. M. Jenkins
Analyzing compliant structures, such as elastomers, membranes, and flexible composites, including:
The VPI sensor is the heart of this full-field vibration imaging system. It is a multi-point measurement system which can be used for modal analysis, design studies, nondestructive testing, and system identification. The VPI system uses laser doppler interferometry to make accurate noncontact vibration measurements on complex systems without the drawbacks of conventional vibration testing techniques.
Points are scanned in a raster-like manner under adjustable computer control. Spatial resolutions of 1 mm diameter at 20 m are possible at up to 50 points per second scan rates. Loading frequencies range from DC to 3000 kHz. Vibration velocities from 0.001 – 1000 mm/s at working distance of up to 200 m are possible. A CCD camera falicitates setup and post-processing.
Click here to see laser vibrometer picture of the first axisymmetric circular membrane vibration mode
Ometron SPATE 4000 Scanning Infrared Radiometer.
The SPATE (Stress Pattern Analysis by Thermal Emission) system detects the infrared flux emitted from a surface as a result of the minute temperature changes in a cyclically stressed structure. The technique dates from investigations by Lord Kelvin during the middle 19th century. Within the elastic range, a reversible coupling exists between the mechanical energy of the applied loads and the thermal internal energy of the material body. For adiabatic conditions, the change in stress (sum of principal stresses), and the corresponding change in temperature, is linear and independent of the loading frequency. Temperature history (dc or transient) is available directly as well.
Points are scanned in a raster-like manner under adjustable computer control. Spatial resolutions of 0.15mm diameter are possible at up to 50 points per second scan rates. A liquid nitrogen cooled IR sensor achieves temperature discrimination on the order of 10-3 Celsius, and specimen temperatures can exist up to 800 Celsius. Loading frequencies range from 0.5 Hz to 50 kHz. Working distance is 0.1 m to infinity. A CCD camera falicitates setup and post-processing.
Click here to see some results from thermal analysis of membranes
Other compliant structures analyzed have included high-altitude scientific balloons, submerged membrane breakwaters, and flexible composite materials. Click here to see NASA Goddard Sunshield Test
For more information contact Dr. C. Jenkins
Gossamer Spacecraft: Membrane and Inflatable Structures Technology for Space Applications
C. H. M. Jenkins, Editor, Progress in Astronautics and Aeronautics Hardcover, 586 page(s), ISBN or Order Number: 1-56347-403-4, Copyright: 2001
This volume addresses a wealth of issues associated with the fascinating technology of gossamer spacecraft. The organization is such that topical sections have been assembled, with many experts in the field bringing together, in one place, the state of the art of membrane/inflatable structure technology for space applications. The content spans a broad range, from that accessible to the lay-technical reader, to more theoretical discussions aimed at the engineer and scientist. Twenty-two chapters plus appendices are included.
The book begins with a broad overview of membrane/inflatable applications in space technology. Then an historical review is given, the depth and breadth of which the uninitiated reader may find surprising. Sections then focus on the fundamental underpinnings of membrane/inflatables technology, beginning first with the mechanics and physics of membrane structures. Then follows chemical and processing issues related to membrane materials, such as developments in the deployment and subsequent rigidization of membrane/inflatables. Among other testing issues, the unique challenges associated with ground testing of these highly compliant structures is given.
The later portion of the volume deals with state of the art in the science, concepts, and designs of modern space mission applications of membrane/inflatables. These range from passive structures such as shades and sails, to high precision structures such as radar and radiometers, to human habitats for space exploration.
For More Information, Please Contact: Dr. Christopher H. M. Jenkins
For Purchasing, Please Visit: http://store.aiaa.org/moreinfo.cfm?productid=885&Search=NO
The Compliant Structure Laboratory (CSL) has recently consulted for the Physics Department at Princeton University, New Jersey. We used the nonlinear code ABAQUS for finite element analysis of the structural design of the Borexino Solar Neutrino Detector. Both elastic and viscoelastic analysis were performed.
For details, please visit: Borexino Design Report
Ometron VPI 4000 Scanning Laser-Doppler Vibrometer
The VPI sensor is the heart of this full-field vibration imaging system. It is a multi-point measurement system that can be used for modal analysis, design studies, nondestructive testing, and system identification. The VPI system uses laser doppler interferometry to make accurate noncontact vibration measurements on complex systems without the drawbacks of conventional vibration testing techniques.
Points are scanned in a raster-like manner under adjustable computer control. Spatial resolutions of 1 mm diameter at 20 m are possible at up to 50 points per second scan rates. Loading frequencies range from DC to 3000 kHz. Vibration velocities from 0.001 – 1000 mm/s at working distance of up to 200 m are possible. A CCD camera facilitates setup and post-processing.
Laser vibrometer making membrane vibration measurements at AFRL.
Vibrometer results showing first asymmetric vibration mode.
Scale-model sunshield ready for the vacuum chamber at NASA Goddard.
Laser vibrometer at NASA Goddard ready for vibration testing of the scale-model sunshield.
Ometron SPATE 4000 Scanning Infrared Radiometer
Points are scanned in a raster-like manner under adjustable computer control. Spatial resolutions of 0.15mm diameter are possible at up to 50 points per second scan rates. A liquid nitrogen cooled IR sensor achieves temperature discrimination on the order of 10-3 Celsius, and specimen temperatures can exist up to 800 Celsius. Loading frequencies range from 0.5 Hz to 50 kHz. Working distance is 0.1 m to infinity. A CCD camera facilitates setup and post-processing.
Other Major Equipment
Other major equipment available to the lab includes:
Interfacial Force Microscope Atomic Force Microscope
FT-IR Spectrometer (NIR and MID) FT-IR Spectrometer (MID and microscope)
X-Ray Diffractometer Laser Raman Spectrometer
Scanning Electron Microscope Transmission Electron Microscope
Mini-Materials Testing System Image Analyzer
100 kip Materials Testing Machine Holographic and fiber optic analysis
Dynamic Materials Analyzer Thermo-mechanical Materials Analyzer
Dynamic Scanning Calorim
Home Web Designer: Sunil Chiluvuri, Mohammad Masum Hossain & N.M. Awlad Hossain, July 2001.