Reusable holders have been devised for evaluating high-temperature, plasma-resistant re-entry materials, especially fabrics. Typical material samples tested support thermal-protection-system damage repair requiring evaluation prior to re-entry into terrestrial atmosphere. These tests allow evaluation of each material to withstand the most severe predicted re-entry conditions

Daniels, Christopher C.

NASA Technical Reports Server

8 NASA Tech Briefs, August 2010
Locking Nut With Stress-Distributing Insert
Lyndon B. Johnson Space Center, Houston, Texas
An improved locking nut comprises
(1) an internally threaded shell, partly
resembling a conventional nut, that can
be engaged by a wrench or other tool,
and (2) an internally and externally
threaded insert that engages the threads
of the shell and a bolt. Whereas some
prior locking nuts are plated over their
entire surfaces for lubrication and pre-
vention of galling caused by engage-
ment of threaded surfaces, this nut in-
cludes plating (silver or other soft
material) only on the threaded surfaces
of the insert, which, during engage-
ment, are enclosed. The elimination of
external plating reduces the likelihood
of contaminating adjacent equipment. 
The insert makes an interference fit
A specially configured seal system (see
figure) has been developed and pro-
duced that provides a barrier to gas leak-
age between a pressurized module and
its external environment. The seal sys-
tem includes a shroud covering that
both protects the sealing surface from its
environment when not in use and re-
tracts to expose the sealing surface when
engaged. The seal system is constructed
and arranged to mate with a replicate
seal system or with a flat surface. When
mated with a replicate seal system, the
seal system functions when the two seal-
ing surfaces are aligned or misaligned.
The seal system can operate over a wide
range of temperatures, limited only by
the glass transition and melt tempera-
tures of the material from which the
sealing surface is manufactured.
This work was done by Christopher C.
Daniels of The University of Akron for Glenn
Research Center. Further information is con-
tained in a TSP (see page 1).
In accordance with Public Law 96-517,
the contractor has elected to retain title 
to this invention. Inquiries concerning
rights for its commercial use should be ad-
dressed to:
Office of Technology Transfer
The University of Akron
Akron, Ohio 44325-2103
(330) 972-7840
Email: uarf@uakron.edu
Refer to LEW-18442-1, volume and num-
ber of this NASA Tech Briefs issue, and the
Seal With Integrated Shroud for Androgynous Docking 
and Berthing
Seal prevents gas leakage between the pressurized module and its external environment.
John H .Glenn Research Center, Cleveland, Ohio
The Shroud Covering protects the sealing sur-
face from the environment when not in use
(top) and retracts when mated (bottom).
Adaptable Holders for Arc-Jet Screening Candidate Thermal
Protection System Repair Materials
Lyndon B. Johnson Space Center, Houston, Texas
Reusable holders have been devised
for evaluating high-temperature,
plasma-resistant re-entry materials, espe-
cially fabrics. Typical material samples
tested support thermal-protection-sys-
tem damage repair requiring evaluation
prior to re-entry into terrestrial atmos-
phere. These tests allow evaluation of
each material to withstand the most se-
vere predicted re-entry conditions. 
In pursuit of this purpose, the holders
are capable of supporting the material
samples in a stagnation orientation
(normal to the flow) with respect to the
impinging plasma flow. The holder de-
sign allows rapid installation and
change-out of 2.8 in. (≈ 71 mm) diame-
ter samples and can accommodate sam-
ple thicknesses from fabrics to more
than 0.5 in. (≈ 13 mm). Each holder
consists of an interlocking set of rings,
constructed of silicon carbide coated
graphite, that clamp together concentri-
cally in such a manner as to restrain the
sample during a test. The sample is
mounted in front of a washerlike back-
ing plate to simulate the repair of a
damaged section of reinforced carbon-
carbon (RCC), such as that used on the
Space Shuttle Orbiter.
This work was done by Joe Riccio of John-
son Space Center and Jim D. Milhoan of
Lockheed Martin Corp. Further information
is contained in a TSP (see page 1).MSC-
24109-1
https://ntrs.nasa.gov/search.jsp?R=20100028882 2019-08-30T10:46:35+00:00Z
NASA Tech Briefs, August 2010 9
with the bolt thread, helping to lock the
shell against loosening during vibra-
tion. In response to bolt tension upon
tightening, the insert undergoes slight
elongation that helps distribute the ten-
sion along the full length of thread en-
gagement. The locking nut helps to dis-
sipate vibrational energy through
microscopic frictional rubbing between
the threads of the insert and the
threads of the shell. The soft plating
may contribute to damping of vibra-
tions. Rounding of the outer end of the
shell reduces the potential for damage
to nearby equipment or injury to
nearby persons.
This work was done by Rahmatollah F.
Toosky and Scott Forest of McDonnell Dou-
glas Corp. for Johnson Space Center. Further
information is contained in a TSP (see page 1).
Title to this invention, covered by U.S.
Patent No. 5,860,779, has been waived
under the provisions of the National Aero-
nautics and Space Act {42 U.S.C. 2457 (f)}.
Inquiries concerning licenses for its commer-
cial development should be addressed to: 
McDonnell Douglas Corp., 
A wholly owned subsidiary of The Boeing Co.
PO Box 2515
Seal Beach, CA 90740-1515
Refer to MSC-23062-1, volume and num-
ber of this NASA Tech Briefs issue, and the
page number.


Locking Nut with Stress-Distributing Insert

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