A heating and cooling apparatus capable of cyclic heating and cooling of a test specimen undergoing fatigue testing is discussed. Cryogenic fluid is passed through a block clamped to the speciment to cool the block and the specimen. Heating cartridges penetrate the block to heat the block and the specimen to very hot temperaures. Control apparatus is provided to alternatively activate the cooling and heating modes to effect cyclic heating and cooling between very hot and very cold temperatures. The block is constructed of minimal mass to facilitate the rapid temperature changes

Gardner, M. R.

Imig, L. A.

English

NASA Technical Reports Server

United States Patent [191 
Imig et al. 
[111 4,346,754 
[45] Aug. 31, 1982 
HEATING AND COOLING SYSTEM 
Inventors: Leland A. Imig, Goehner, Nebr.; 
Mickey R. Gardner, Gloucester 
Point, Va. 
The United States of America as 
represented by the Administrator of 
the National Aeronautics and Space 
Administration, Washington, D.C. 
Assignee: 
Appl. No.: 145,208 
Filed: Apr. 30, 1980 
Int. Cl.3 .............................................. F25B 29/00 
U.S. C1. ........................................ 374/46; 165/27; 
165/61; 165/80 E 165/12; 62/62; 62/514 R 
Field of Search ................... 165/11 R, 12, 27, 61, 
165/63, 64, 80 E, 62/62, 514 R, 78; 73/15 R, 
15.4 
References Cited 
U.S. PATENT DOCUMENTS 
3,143,167 SA964 
3,406,742 10/1968 
3,453,863 7/1969 
3,599,475 8/1971 
4,107,937 SA978 
4,117,881 10/1978 
Vieth ..................................... 165/64 
Naumann et al. .................... 165/12 
Scott ................................... 73/15 R 
Dubouch et al. ................... 73/15 R 
Chmiel .................................... 62/64 
Williams et al. ........................ 165/2 
4,134,447 1/1979 Jennings et al. ...................... 165/30 
FOREIGN PATENT DOCUMENTS 
2432734 4/1980 France ................................ 73/15 R 
435481 7/1975 U.S.S.R. ............................. 73/15R 
533850 11/1976 U.S.S.R. ............................. 73/15R 
563603 6/1977 U.S.S.R. ............................. 73/15R 
Primary Examiner-Albert W. Davis 
Assistant Examiner-Margaret A. Focarino 
Attorney, Agent, or Firm-Howard J. Osborn; John R. 
Manning; William H. King 
ABSTRACT [571 
A heating and cooling apparatus capable of cyclic heat- 
ing and cooling of a test specimen undergoing fatigue 
testing. Cryogenic fluid is passed through a block 10 
clamped to the specimen 11 to cool the block and the 
specimen. Heating cartridges 13 penetrate the block 10 
to heat the block and the specimen 11 to very hot tem- 
peratures. Control apparatus 36 and 46 is provided to 
alternately activate the cooling and heating modes to 
effect cyclic heating and cooling between very hot and 
very cold temperatures. The block 10 is constructed of 
minimal mass to facilitate the rapid temperature change 
thereof. 
9 Claims, 4 Drawing Figures 
FATIGUE TESTING 
MACHINE 
CONTROL 
CONTROL 
46 
I I 
https://ntrs.nasa.gov/search.jsp?R=19830025950 2020-03-22T01:04:05+00:00Z
U.S. Patent Aug. 31, 1982 Sheet 1 of 2 4,346,754 
SUPPLY 
46 
I f  
CONTROL - 
BOX 
CONTROL 
BOX 
4t- SWITCH - TI MER 
1 
- 7  
(40 48 
POWER 
SUPPLY : FIG. 1 
U.S. Patent Aug. 31, 1982 Sheet 2 of 2 4,346,754 
10 
L FIG. 2 
24 
1 
Dr 
3 
r 
2: 2o 
FIG. 
FIG. 4 
4,346,754 
HEATING AND COOLING SYSTEM 
ORIGIN O F  THE INVENTION 
The invention described herein was made by employ- 
ees of the U.S. Government and may be manufactured 
and used by or for the Government for governmental 
purposes without the payment of any royalites thereon 
or therefor. 
BACKGROUND O F  T H E  INVENTION 
The present invention relates to material fatigue test- 
ing and particularly to an apparatus for maintaining a 
test specimen at a control temperature and for cycli- 
cally inducing a range of temperatures between cryo- 
genic and elevated. 
Spacecraft endure a wide range of temperatures dur- 
ing space flights. The portion of the spacecraft exposed 
to the intense direct rays of the sun experience elevated 
temperatures while the portion of the spacecraft shaded 
from the sun experience relatively lower temperatures. 
Moreover, the spacecraft as a whole experiences low 
temperatures during travel through the shadow of a 
planet or other heavenly body. The temperatures vary 
from cryogenic, hundreds of degrees below 0" centi- 
grade, to elevated, hundreds of degrees above 0" centi- 
grade. Furthermore, the temperature of a particular 
spacecraft structural component may experience a wide 
range of temperatures in a short period of time during 
rotation of the spacecraft, in that the particular compo- 
nent is alternately exposed to the sun's rays and shaded 
therefrom. 
In the testing of structural components of spacecraft 
it is desirable to simulate as closely as possible the perti- 
nent environmental conditions the structure will exDeri- 
Control devices are provided to supply liquid nitrogen 
through the block and for power to the heating car- 
tridges in a manner to maintain a preselected tempera- 
ture. Cyclic operation between elevated and cryogenic 
5 temperatures with hot and cold cycles of unequal 
lengths, and at arbitrary times is possible by utilizing a 
timing device to alternate between heating and cooling. 
The small mass of the block is the key feature of the 
invention because its temperature can be changed rap- 
10 idly allowing quick heating and cooling of the test spec- 
imen. 
An object of the invention is to provide an apparatus 
for heating and cooling a fatigue test specimen. 
It i s  another object of the invention to provide a 
l5 heating and cooling apparatus having a minimal mass to 
allow quick cooling and heating thereof. 
A further object of the invention is a heating and 
cooling apparatus having the foregoing advantages and 
which is capable of cyclic operation between cryogenic 
Another object of the invention is a heating and cool- 
ing apparatus having the foregoing advantages which 
can be easily custom made to fit fatigue test samples 
connected in place to a testing machine. 
A further object of the invention is a heating and 
cooling apparatus having the foregoing advantages 
which is inexpensive and uses small amounts of energy 
to heat, and cryogenic materials to cool. 
Other objects and advantages of the present invention 
will be readily apparent from the following description 
and drawings which illustrate the preferred embodi- 
ment of the invention. 
SUMMARY OF T H E  INVENTION 
2o and very hot temperature. 
25 
3o 
?.e 
J J  
ence in space. Accordingly, in the fatigue testi;g of The present invention involves a heating and cooling 
structural components of spacecraft it is desirable to being of to rapid 
expose the structure to extreme high and low tempera- 
tures while maintaining a load on the test specimen. 
and heating thC3W)f. Cooling means are provided for 
cooling the block to cryogenic temperature and heating 
Relatively massive commercial systems are available in 40 means are provided for heating the block to elevated 
the prior art either as heat Sources or as cryogenic temperature. Control means are provided for alter- 
sources but none include cyclic temperature capabilities nately activating the heating means and the cooling 
into the cryogenic temperature range. In some known means. 
systems test specimens are alternately transported be- 
tween a cryogenic chamber and a hot chamber. How- 45 
ever, these systems are unacceptable for tests in which FIG. 1 is a perspective view of the preferred embodi- 
the specimen position must remain fixed as in a testing ment of a heating and cooling apparatus according to 
machine. the present invention in place on a fatigue test specimen; 
The massive commercial systems of the prior art are FIG. 2 is a sectional view of the block of the Pre- 
incompatible with the fatigue testing machine designed 50 ferred embodiment ofthe heating and cooling apparatus 
to test small samples. Furthermore, they require large 
amounts of electricity for heating, large amounts of FIG. 3 is a cross-sectional view taken along line 111- 
cryogenic material for cooling, and do not provide 
cyclic temperature capability. The systems which trans- 
port this space specimen between hot and cold cham- 55 
bers are inherently incompatible with the stationary 
configuration of a fatigue testing machine. 
The present invention alleviates to a great extent the 
short comings of the prior art. In the present invention 
the same block having a small mass is used to transfer 60 
both elevated and cryogenic temperatures to the test 
sample. The block is clamped to the test specimen dur- 
ing fatigue testing. Liquid nitrogen is directed through 
the block for cooling it to cryogenic temperatures. 
block, are provided for heating the block to elevated 
temperatures. A thermocouple probe penetrates the 
block to monitor the temperature of the test specimen. 
BRIEF DESCRIPTION O F  T H E  DRAWINGS 
according to the Present invention; 
-111 of FIG. 2; 
and 
IV-IV of FIG. 3. 
FIG. 4 is a cross-sectional view taken along line 
DETAILED DESCRIPTION O F  THE 
PREFERRED EMBODIMENT 
Referring now to FIG. 1 there is shown in perspec- 
tive the preferred embodiment of the invention desig- 
nated generally by the reference numeral 8. Flat elon- 
gated test specimen 11 is connected at both ends thereof 
to a fatigue test machine (not shown). Two identical 
Heating cartridges accommodated by apertures in the 65 blocks 10 and 10a are clamped to specimen 11 by 
clamps 32 and 32a. The clamps 32 and 32a are made of 
spring or resilient material and force the block 10 and 
10a against the specimen. It is to be understood that 
4,346,754 
3 4 
other types of clamps might be utilized. Positioning back probe 30 (which is in contact with specimen 11) 
plates 38 and 380 are affixed to specimen 11 above and senses that the desired temperature has been achieved. 
below blocks 10 to preclude slippage of block 10 along Solenoid valve control 36 then closes solenoid valve 35 
specimen 11 and to keep the specimen from buckling. interrupting the flow of liquid nitrogen. When heat 
Coolant flow is applied through the block by coolant 5 conducted from the surroundings tends to warm speci- 
supply 34 in fluid communication via inlet pipes 26 with men 11; thermocouple probe 30 actuates solenoid valve 
chambers (see FIGS. 3-51 of block 10. The coolant of control 36 to open solenoid valve 35 to allow nitrogen 
the Preferred embodiment is cryogenic, typically liquid to flow, thus maintaining temperature within a narrow 
nitrogen. Coolant is exhausted as a vapor and exhaust range. 
pipes 28 provide fluid communication between block 10 10 The system functions similarly when used to maintain 
and the atmosphere. test specimens at constant elevated temperature. In this 
Solenoid operated valve 35 controls coolant flow case, however, thermocouple probe 30 indicates the 
through inlet pipe 26. Thermocouple probe 30 extends temperature of the specimen to control 46 which con- 
through block 10 to a position adjacent the specimen 11 trols electrical power to heating cartridges 13. 
to monitor temperature thereof. The system operates alternately as a heater or cooler, 
A signal indicative of specimen 11 temperature is sent in the ways described above, by introducing a device to 
via wire 31 and switch 40 to 36 alternately power liquid nitrogen controller 36 or  ele- 
imen 11 temperature at a desired set level. The solenoid quirements of a particular testing program. The system 
control 36 and the solenoid valve 35 are of conventional 20 has operated successfully in a test wherein heat (6000 F.) 
and cold (-250" F.) were achieved alternately by a design and available commercially. 
nately to the controllers 36 and 46. Cyclic operation 
wire 15. A signal indication of specimen 11 temperature 25 and cold cycles of unequal lengths and at arbitrary times 
is sent via wire 31 and switch 40 to power supply con- depends on the characteristics of the device which acti- trol46 whereby the power supply is activated to main- vates controllers 36 and 46. If the device 48 which tain specimen 11 temperature at a desired set level. 
Timing device 48 operates switch 4o to elect heating activates controllers 36 and 46 is the same device that 
l 5  
whereby 35 is Operated to maintain spec- vated temperature controller 46 according to the re- 
Heating l3 penetrate through simple timing device 48 which provides power alter- 
37 provides power to l3 via between elevated and cryogenic temperatures with hot 
'' and provide a Source Of heat thereto' Power 
or  cooling of the block for cyclic operation. The power 30 sequences loads 
supply 37, the switch 40, power supply controller 46, 
and timer are also of conventional design and are avail- 
to specimen 11, the loading and 
temperature Of specimen l1 can be either synchronized 
or phased at the discretion Of the person conducting the 
able from commercial suppliers. The details of the con- tests. The latter mode of operation is the operation for 
trol structure and operation are considered known to which this system was devised. In actual tests it was 
35 found that a test specimen could be cooled from +600" one skilled in the art and need not be explained. 
Refer now to FIG. 2 there being shown a view of F. to -250" F. in a time interval of 15 minutes and 
block 10 of the preferred embodiment. Heating element heated from a -250" F. to +6000 F. in en- 
apertures 12 extend through block 10 and are sized to abling a cycle to be completed in 25 minutes. The small 
accept heating element cartridges 13 (see FIG. 1). CY- mass of block 10 is a key feature of the invention be- 
lindrical coolant chambers 14 extend through block 10. 40 cause its temperature can be changed relatively rapidly. 
Slots or conduits 16 and 17 establish fluid communica.. The above description and drawings are only illustra- 
tion between chambers 14. tive of one embodiment which achieves the objects, 
features and advantages of the present invention, and it 
through block 10 and is sized to accept thermocouple is not intended that the present invention be limited 
probe 30 (see FIG. 1). Securing screw 21 is provided to 45 thereto. Any modification of the Present invention 
hold probe 30 in place. Inlet conduit 18 establishes fluid which comes within the spirit and scope of the follow- 
communication between inlet pipe 26 and slot 17; exit ing claims shall be considered part of the present inven- 
conduit 19 establishes fluid communication between tion. 
slot 16 and exhaust pipe 28. What is claimed as new and desired to be secured by 
block 10 by screws or  other suitable means (not shown) 1. A device for heating and cooling a specimen under- 
to enclose chambers 14 and slots 16 and 17. 
Turning to FIG. 4 another view is shown for clarity a fatigue testing machine; 
and to show cap 22 iI1 position to establish a closed a test specimen connected to said fatigue testing ma- 
coolant passageway within block 10 consisting of slots 55 chine; 
16, 17 and chambers 14. block means having a small mass to enable rapid 
In operation of the invention when used to maintain a cooling and heating thereof; 
constant cold temperature on the test specimen the said block means being constructed and arranged to 
coolant, typically liquid nitrogen (not shown), is intro- engage said test specimen; 
duced through coolant inlet pipe 26 by solenoid valve 60 clamping means for securing said block means to said 
35 from remote pressurized coolant source 34. Liquid test specimen; 
nitrogen enters coolant containing chambers 14 and cooling means for cooling said block means and test 
slots 16, and 17 of block 10 and absorb heat from the specimen to very cold temperatures; 
surrounding material of block 10 including heat con- heating means for heating said block means and test 
ducted from specimen 11. Absorbed heat vaporizes the 65 specimen to very hot temperatures; and 
liquid nitrogen; the vapor then exhausts to the atnio- contol means for selectively activating said heating 
sphere through exhaust pipes 28. Liquid nitrogen con- means and said cooling means to selectively heat 
tinues to flow into block 10 until thermocouple feed- and cool said test specimen. 
Refer to FIG. 3. Thermocoup~e bore 20 
Caps 22 and 24 (shown in FIG. 4) are secured to 50 Letters Patent o f t h e  United States is: 
going fatigue testing comprising: 
4,346,754 
5 6 
2. A device as in claim 1 wherein said control means 6. A device as in claim 2 wherein said control means 
includes temperature sensing means for indicating test further comprises a timing device for selectively acti- 
specimen temperatures; vating said cooling means and said heating means to 
cooling control means for selectively activating and effect cyclic temperature of the test specimen between 
deactivating said cooling means respondent to the 5 very hot and very cold temperatures at desired time 
temperature sensitive means to maintain a desired intervals. 
cold temperature; and 7. A device for heating and cooling a test specimen as 
heating control means for selectively activating and in claim 1 wherein said block means is a pair of blocks; 
deactivating said heating means respondent to the one of said blocks engaging one side of said test speci- 
temperature sensitive means to maintain the desired 10 men and the other block engaging the other side of 
hot temperature. said test specimen substantially surrounding said 
test specimen to facilitate rapid heat transfer. 
8. A device for heating and cooling a test specimen as 
in claim 1 including means for positioning said block 
15 means on said test specimen and preventing buckling 
thereof. 
9. A device for heating and cooling a test specimen as 
in claim 1 wherein said block means includes multiple 
chambers and conduits to reduce the mass thereof and 
3. A device as in claim 1 wherein said cooling means 
includes a supply of cryogenic fluid and conduit means 
extending from said supply of cryogenic fluid and 
through said block means. 
4. A device as in claim 1 wherein said heating means 
includes at least one heating cartridge penetrating said 
block means. 
5. A device as in claim 3 wherein said cooling control 
means includes a solenoid controlled valve positioned in 20 facilitate maximum flow of a heat transfer medium. 
said conduit means. * * * * *  
25 
30 
35 
40 
45 
50 
55 
60 
65 


Heating and cooling system

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