Split-screw grips for tensile testing provide uniform loading on the specimen shoulders. Holes in the heads enable the screws and specimen to be threaded as an assembly into a grip body, closely controlled guides and seats afford positive seating, and precision machining of mating surfaces minimizes misalignment effects

Skalka, R. J.

Vandergrift, E. F.

English

NASA Technical Reports Server

Tensile Testing 
Mechanism N
Grip 
Bodies 
Tensile 
Specim 
I 
December 1967	 Brief 67-10628 
ICY C 
()	
AEC-NASA TECH BRIEF 
AEC-NASA Tech Briefs describe innovations resulting from the research and development program 
of the U.S. AEC or from AEC-NASA interagency efforts. They are issued to encourage commercial 
application. Tech Briefs are published by NASA and may be purchased, at 15 cents each, from 
the Clearinghouse for Federal Scientific and Technical Information, Springfield, Virginia 22151. 
Tensile Testing Grips Are Easily Assembled under Liquid Nitrogen 
Movable 
The problem:	 How it's done: 
To design a specimen gripping device for tensile 	 The split-screw grips were developed for testing 
testing that provides uniform loading on the specimen 	 specimens of beryllium irradiated at 140°R. At the 
shoulders. The device must be easily assembled under	 beginning of the test procedure, the specimen and 
liquid nitrogen (LN2), should minimize misalignment 	 split-screw grips are under LN2. Tongs are used to 
effects, and afford positive sealing to the specimen.
	
	 place the two matching halves of the screw around

the specimen and onto the pins of the wrench. This 
The solution:	 assembly is threaded into the top grip body; then the 
Split-screw grips featuring: (I) holes in the split-	 movable crosshead is run up so that the specimen is 
screw heads such that when matched to corresponding 	 hanging into the bottom grip body. Another pair of 
pins on a special wrench, -the screws and specimen 	 split-screw grips is assembled around the specimen 
can be threaded as an assembly into a grip body;	 and threaded in with the opposite side of the wrench. 
(2) closely controlled guides and seats which afford 	 Positive location of the holes and pins eliminates 
positive seating; and (3) precision machining of mating 	 mismatching of threads and subsequent jamming. The 
surfaces to minimize misalignment effects. 	 split design offers uniform loading around the entire 
(continued overleaf) 
This document was prepared under the sponsorship of the Atomic 
Energy Commission and/or the National Aeronautics and Space 
Administration. Neither the United States Government nor any per-
son acting on behalf of the United States Government assumes any
liability resulting from the use of the information contained in this 
document, or warrants that the use of any information, apparatus, 
method, or process disclosed in this document may not infringe pri-
vately owned rights.
https://ntrs.nasa.gov/search.jsp?R=19670000627 2020-03-11T21:34:59+00:00Z
shoulder of the specimen. The guide and seats pro-
vide controlled surfaces so that no contribution to 
misalignment is made and correct seating of the speci-
men is positive and reproducible. Assembly under 
LN2 is relatively fast and easy, and the operation 
does not necessarily require viewing to ensure a proper 
fit. The inside surface and edges of the wrench and 
the ends of the tongs are taped to prevent scratching 
the specimen. The wrench handle is insulated to pro-
tect the hands. 
Note: 
Inquiries concerning this innovation may be di-
rected to:
Technology Utilization Officer 
AEC-NASA Space Nuclear Propulsion 
Office 
U.S. Atomic Energy Commission 
Washington, D.C. 20545 
Reference: B67-10628
Patent status: 
No patent action is contemplated by AEC or 
NASA.
Source: R. J. Skalka and E. F. Vandergrift

of Westinghouse Astronuclear Laboratory

under contract to

AEC-NASA Space Nuclear Propulsion Office 
(NUC- 10524) 
Brief 67-10628	 Category 05


Tensile testing grips are easily assembled under liquid nitrogen

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