6th International Conference on VHCF
October 15–18, 2014, Chengdu, China

Development and Several Additional Performances of Dual-Spindle Rotating
Bending Fatigue Testing Machine GIGA QUAD
Taizoh Yamamoto1*, Akio Kokubu1, Tatsuo Sakai2, Yuki Nakamura3
1

Yamamoto Metal Technos Co. Ltd., 4-7 Setoguchi 2-chome, Hirano-ku, Osaka, 547-0034 Japan
2
Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu, Shiga, 525-8577 Japan3
Toyota National College of Technology, 2-1 Eiseicho, Toyota, Aichi, 471-8525 Japan* Corresponding author: yamakin@mx1.alpha-web.ne.jp

Abstract In order to investigate the fatigue characteristics of metallic materials experimentally, a long
period of time is required to get sufficient number of S-N data. In recent years, in order to overcome thisdifficulty, multi-type rotating bending fatigue testing machine whose name is GIGA QUAD has beendeveloped by Yamamoto Metal Technos Co., Ltd., in which four specimens can be tested simultaneously.
In this time, some additional new functions have been developed as follows;(1) 'high and low temperature environmental testing unit' whose target temperature is in a range of 600 deg.C
and -150deg.C, (2) 'constant temperature/humid environmental testing unit' combined with the conventional
corrosive cell, (3) ‘fracture alarm unit’, and (4) ‘2-step variable loading unit’.
By combining these new functions with the machine of GIGA QUAD, one can perform the fatigue tests
efficiently corresponding to the respective requirements for researchers in both of academic and industrial
sectors.
Keywords High temperature environmental testing unit, Low temperature environmental testing unit,
Constant temperature/humid environmental testing unit, Fracture alarm unit, 2-step variable loading unit

1. Introduction

Stress amplitude a , MPa

One of difficulties in fatigue tests for structural materials is to take a long time to perform thefatigue test. Fatigue tests are usually conducted toward the loading cycles of N=10 7, but the fatigue
property in gigacycle regime is also focused as an important subject in recent years[1]-[8]. In such along life region, a tremendous long period is required to perform fatigue tests. If the fatigue test is
performed at the loading frequency of 50Hz, it takes more than 200 days to reach 109 cycles of theload application. It means that it takes very long term for us to obtain one S-N curve.
In addition, since the fatigue life of any metallic material has a distinct scatter, sufficient number of
specimens should be tested to obtain the reliable fatigue property. An example of such fatigue test
data for a bearing steel in very high cycle regime are shown in Figure 1 as an S-N diagram[5]. TypeI indicates the conventional bearing steel, whereas Type II indicates the high purity bearing steel.
1800

Type Ⅰ surface slip
Type Ⅰ fish-eye
Type Ⅱ surface slip
Type Ⅱ fish-eye

1600
1400
1200
1000
800
103

104 105 106 107 108 109 1010
Number of cycles to failure N f , cycles
Figure 1. Typical example of fatigue test data for bearing steel in very high cycle regime-1-

6th International Conference on VHCF
October 15–18, 2014, Chengdu, China

Open marks indicate the data in the surface initiated fracture, while solid marks give those data in
the interior inclusion initiated fracture. In order to complete a series of fatigue tests to obtain all thedata in Fig.1, it takes several years for one kind of metallic material. This circumstance introduces aserious difficulty to every researcher in the area of “Metal Fatigue” from technological andeconomical backgrounds.
If the high loading frequency such as ultrasonic fatigue test was accepted to save the testing time,
temperature raising of the specimen due to the internal friction would take place and some coolingsystem or intermittent loading system should be furnished to examine the original fatigue
property[9-12]. Thus, the acceleration fatigue test by ultrasonic technology would cause new
difficult subjects as the fatigue testing method to obtain the fatigue property at the usual frequency.
In order to overcome these difficulties, authors have developed special types of fatigue testingmachines in rotating bending, in which four specimens can be tested simultaneously[13,14]. Thus aseries of fatigue tests even in gigacycle regime can be carried out within a reasonable time period.
Based on this advantageous performance, the name of “GIGA QUAD” was accepted for this newmachine. By using this machine of GIGA QUAD, fatigue tests can be performed much quickly
comparing with the conventional testing machines, even if it is used with various environment
options. Accordingly, this machine is useful to file up a number of fatigue test data in gigacycle
regime for various kinds of metallic materials, and such databases can provide the fundamental
design data for mechanical structures in the wide variety of the engineering application.

2. Dual-Spindle Rotating Bending Fatigue Testing MachineThis machine has two spindles and two specimens can be mounted at both ends of each spindle asindicated in Fig.2 and Fig.3. Each spindle is driven by an electric motor via a V belt and the numberof revolution is counted by means of photo-sensor. Thus, this machine can perform fatigue tests for
4 specimens simultaneously. In order to apply the testing load, the corresponding weight issuspended through a helical spring attached to the outer bearing block. The rotating speed of thespindle, that is, the testing speed is 3,150rpm (52.5Hz)
GIGA QUAD has two types of ‘YRB200’ and ‘YRB200L’ according to the loading capacity(Maximum load). The maximum load of YRB200 is 20kg, whereas the load of YRB200L is 80kg.

Table 1. Specification of the Device

YRB200YRB200L

Motor

0.2kw-4P

0.4kw-4p

Power

380V

380V

Collet Chuck

Φ5~10

Φ10~16

Max Load

20kg * 4

80kg * 4

Spindle Speed

3,150rpm

3,150rpm

Weight

140kg

170kg

Size

470*400*1050

800*660*1100

Spindle Number

2

2

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6th International Conference on VHCF
October 15–18, 2014, Chengdu, China

Figure 2. GIGA QUAD YRB200

Figure 3. GIGA QUAD YRB200L

Hourglass type of specimen as shown in Fig.4 is accepted as a formal specimen. Diameter of thecritical section ‘Φβ’ is designed as to give the reasonable stress level for the each material, while thediameter of the specimen grip ‘Φγ’ may be decided by user freely. Collet chucks with different
diameters such as 6mm, 8mm and 10mm are prepared in advance. Among them, the user canchoose the most preferable collet chuck depending on the individual circumstance for the testingmaterial.

Figure 4. Shape and dimensions of the specimen-3-6th International Conference on VHCF
October 15–18, 2014, Chengdu, China

3. Support for Environmental Testing
3.1. High temperature environmental testing unit
In the applications of metallic materials to power and energy plants, the key components always
work in a high temperature. For example, in the design of gas turbines, it is important to increasegas temperatures in order to attain a high thermal efficiency. For jet engines, an increased
temperature realize higher loads, higher speed and a greater output range. In the case of power
generating gas turbines, the increase of temperature leads to lower fuel consumption, pollution andcost.
Thus, it is necessary to clarify the reliability property of structural materials at high environmental
temperature. Then a high environmental temperature unit was developed as an option for the fatigue
testing machine YRB200 and YRB200L. The unit is expected to contribute to clarify the fatigue
property and fracture mechanism at high environmental temperature.

Figure 5. High temperature environmental testing unit

A spot light-condensed heating method is adopted in the developed high temperature unit. The lightemitted from the halogen lamp is reflected and condensed to the small spot in the center of
specimen. The center of the specimen can be heated rapidly to the temperature of 600 deg.C. A
temperature sensor is used to measure the temperature inside the chamber. And the temperatureinside the chamber is controlled to keep a given value set by the temperature control panel, throughadjusting the input voltage of the lamp automatically. A water cooling system is used to protect
lamp power components from over-heating. An air cooling system is used to cool the bearing of theadapter in the end of the specimen.
【Specification】
Testing Temperature:

Fe 100~600 deg.C
Al 100~250 deg.C
Temperature Control: PID / Power Control
Input ±5 deg.C
Temperature Measurement: 1 deg.C(resolution)
Size of Control Panel: W500*D500*H1400mm
Specimen: YRB200- Φ10 (Standard)
Number of Chambers:
2 (Separate control)-4-6th International Conference on VHCF
October 15–18, 2014, Chengdu, China

Figure 6. Temperature setting

The light from halogen lamp is condensed to the center of the specimen. The environmental
temperature inside the chamber is measured and controlled to a given value. However, thetemperature inside the specimen is different from the set environmental temperature. The difference
between temperatures inside the specimen and the environmental chamber is governed by the heat
conductivity of the specimen. For example, when the specimen should be tested at the temperatureof 200 deg.C, the environmental temperature should be set as 400 deg.C for aluminum alloy while
the temperature for SUS steel is about 170 deg.C. Based on the calibration diagram in Fig.6, one
can set the temperature of the specimen.
【Testing condition】
Loading Mode: Rotating bending
Loading Frequency: 52Hz
Material: S45C
Machine: YRB200① Environmental Temperature: Room
② Environmental Temperature: 500 deg.C【Specimen】

Figure 7. Example of fatigue test result obtained by using the present unit

In order to compare S-N curves at room temperature and 500 deg.C, fatigue tests were carried out
for the S45C steel. In this work, fatigue tests were performed by using the rotating bending fatigue
machine of YRB200 for both temperature conditions. The S-N curve at room temperature is plottedby the blue line, whereas another S-N curve 500 deg.C is plotted by the red line. A remarkabledifference between the S-N curves of room temperature and 500 deg.C is confirmed.
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October 15–18, 2014, Chengdu, China

3.2. Low temperature environmental testing unit
Markets of structural materials applying to the low environmental temperature will further grow in
the near future. The environmental temperature of superconductivity applications is below -150
deg.C. In the progress of the hydrogen society, hydrogen will be transported and stored at a very
low temperature. The market of space exploration is growing quite fast in recent years, especially in
China. And there is also a quite great market in the cold regions, resource exploration of Siberia andthe polar scientific expedition. Thus, it is necessary to clarify the reliable fatigue property ofstructural materials at low environmental temperature.
Then a low environmental temperature unit was developed as an option for the rotating bending
fatigue testing machine YRB200L. The fatigue testing carried out by the YRB200L with thisdeveloped low temperature unit is expected to help clarifying the fatigue property and fracture
mechanism at low environmental temperatures.

Figure 8. Low temperature environmental testing unit

The nitrogen evaporation is used to cool the testing chamber. Through adjusting the flow quantityof liquid nitrogen provided to the environmental chamber, the temperature inside the chamber iscontrolled to be a given value set by the temperature control panel. The evaporated nitrogen isdischarged out through the exhaust pipe with a fan and a blower. A safety booth is set to prevent theoperator breathing in the air with an oxygen concentration lower than the critical value due to theleak of exhaust nitrogen from the low temperature chamber. The O2 censor inside the booth candetect the decrease of oxygen concentration caused by the trouble in exhaust ventilation system. If
the situation exceeds the critical level, charge of the liquid nitrogen is shut down and an alarm isprovided. Even if the O2 censor inside the booth can’t work well, the O2 censor outside the boothalso can detect the decrease of oxygen concentration near the temperature control panel caused byleak of nitrogen from booth. If the critical situation takes place, charge of the liquid nitrogen is shut
down and an alarm is given at the moment.

-6-6th International Conference on VHCF
October 15–18, 2014, Chengdu, China【Specification】
Temperature Control: PID / Input ±5 deg.C
Precision of Temperature Measurement: 0.1 deg.C
Size of Control Panel: W600 * D400 * H1300 mm
Number of Chambers: 2 (Separate temperature control)
Specimen: YRB200L - Φ12 (Standard)

Figure 9.Construction of duplex chamber

A duplex chamber structure is adopted to decrease the growth speed of the frost inside and outside
the low temperature chamber. Liquid nitrogen is sprayed to the center of the specimen to keep agiven testing temperature. The evaporated nitrogen then flows out from the inner chamber to theouter chamber through a gap between the specimen and the inner chamber. When the nitrogen flows
out from the outer chamber, the gas is mixed with the air and the mixed gas is discharged out
through the exhaust ventilation system.

Figure 10. Temperature setting-7-

6th International Conference on VHCF
October 15–18, 2014, Chengdu, China

The liquid nitrogen is sprayed to the center of specimen and the environmental temperature ismeasured and controlled to a given value. However, the temperature inside the specimen is a little
higher than the set environmental temperature. The difference of temperatures between inside andoutside the specimen is governed by the heat conductivity of the specimen. Such a difference for the
A2017 alloy is about 15 deg.C, while the value for SUS304 steel is about 4 deg.C.
【Testing condition】
Loading Mode:

Rotating bending

Loading Frequency:
Material:

52Hz

S45C

Machine: YRB200L① Environmental Temperature: -100 deg.C② Environmental Temperature: Room【Specimen】

Figure 11. Example of fatigue test result obtained by using the present unit

S-N curves at room temperature and -100 deg.C for the S45C steel are compared with each other.
The fatigue tests in both temperature conditions were performed by using the rotating bending
fatigue machine of YRB200L. The S-N curve at room temperature is plotted by the red line,
whereas the S-N curve at -100 deg.C is plotted by the blue line. A remarkable difference between
the S-N curves of room temperature and -100 deg.C is confirmed.
3.3. Fracture alarm unit
A fracture alarm unit which can detect the fracture of specimen and inform the fracture toresearchers via e-mail has been developed. In the case of fatigue test to obtain the S-N property, thetest is repeatedly conducted by using a lot of specimens. In some cases, stress is changed with adefinite time span in order to simulate the actual service loading. Since the fatigue life of eachspecimen has a distinct scatter, it is impossible to know the fatigue life exactly before the fatigue
test. Due to this difficulty, every researcher has to come to the testing machine to confirm whether
the specimen has failed or not.
If the person does not notice the fracture of the specimen, he/she wastes much time to find thefatigue failure even though the number of cycles to failure is recorded. In order to prevent such atime consumption, this unit was originally developed here. Adopting this unit, the researcher can
get the prompt information on the failure immediately after the specimen has failed. Thus, the next
fatigue test can be started soon and the above time consumption can be effectively solved. In
addition to this advantage, researchers’ mental stress to check the fatigue failure can be also
reduced.
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6th International Conference on VHCF
October 15–18, 2014, Chengdu, China

Figure 12. Fracture alarm unit

4. Concluding remarks
Conventional fatigue tests take a long time more than 200days to reach N=109, and a number offatigue test data are required as the fundamental data in the mechanical design. In order to solve
such difficulties, the high performance fatigue testing machine in rotating bending “GIGA QUAD”
has been developed in this work.
Based on a lot of experimental results, the fundamental performance of this testing machine wasconfirmed. Actually these machines are already being used at many laboratories in universities andindustries. Thus, conventional customers and new customers have informed that this testingmachine is successfully used to obtain a number of fatigue data within a reasonable short period.

5. References[1]

T. Sakai, Y. Sato, Y. Nagano, M. Takeda and N. Oguma, Effect of Stress Ratio on Long Life
Fatigue Behavior of High Carbon Chromium Bearing Steel under Axial Loading,International Journal of Fatigue, Vol.28, No.11, (2006), 1547-1554[2]

Bathias, C., P. C. Paris. Gigacycle Fatigue in Mechanical Practice, Marcel Dekker, 2005.

[3]

Sakai T., Ochi Y., Jones J. W. Special Issue on the Third International Conference on VeryHigh Cycle Fatigue held in Kyoto/Kusatsu, Japan on 16-19 September, 2004, International
Journal of Fatigue, 2006; 28: 1437.
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October 15–18, 2014, Chengdu, China[4]

T. Sakai, Review and Prospects for Current Studies on Very High Cycle Fatigue of Metallic
Materials for Machine Structural Use, Journal of Solid Mechanics and Materials Engineering,
Vol.3, No.3, (2009), 425-439.

[5]

N. Oguma, B. Lian, T. Sakai, K. Watanabe, and Y. Odake, Long Life Fatigue Fracture
Induced by Interior Inclusions for High Carbon Chromium Bearing Steels under Rotating
Bending, Journal of ASTM International, Vol.7, No.9, (2010), 1-9.

[6]

W. Li, T. Sakai, Q. Li, L.T. Lu and P. Wang, Effect of Loading Type on Fatigue Properties ofHigh Strength Bearing Steel in Very High Cycle Regime, Materials Science and Engineering,
A, Vol.528, No.15, (2011), 5044-5052.

[7]

H. Mughrabi, Zur dauerschwingfestigkeit im bereich extrem hoher bruchlastspielzahlen:
Mehrstufige lebensdauerkurven, Harterei-technische Mitteilungen, 56 (2001), 300-303.

[8]

T. Sakai, B. Lian, M. Takeda, K. Shiozawa, N. Oguma, Y. Ochi, M. Nakajima, T. Nakamura,
Statistical duplex S–N characteristics of high carbon chromium bearing steel in rotating
bending in very high cycle regime, Int J Fatigue, 32 (2010), 497-504.

[9]

R. Ebara, The Present Situation and Future Problems in Ultrasonic Fatigue Testing – Mainly
reviewed on Environmental Effects and Materials’ Screening, International Journal of Fatigue,28, (2006), 1465-1470.

[10] H. O. K. Kirchner, W. Kromp, F. B. Prinz, P. Trimmel, Plastic Deformation under
Simultaneous Cyclic and Unidirectional Loading at Low and Ultrasonic Frequencies. Mat.
Sci. Eng., 68, (1985), 197-206.
[11] S. Stanzl-Tschegg, Fatigue Crack Growth and Thresholds at Ultrasonic Frequencies,
International Journal of Fatigue, 28, (2006), 1465-1470.
[12] H. Ishii, T. Yamada, Y. Okada, Very High Cycle Fatigue Strengths of Thin Sheet Metals,
Proceedings of VHCF-3, (2004), 420-426.
[13] T. Sakai, M. Takeda, K. Shiozawa, Y. Ochi, M. Nakajima, T. Nakamura and N. Oguma,
Experimental Reconfirmation of Characteristic S-N Property for High Carbon Chromium
Bearing Steel in Wide Life Region in Rotating Bending, J. Soc. Mat. Sci., Japan, Vol.49,
No.7, (2000), 779-785.
[14] T. Sakai, T. Furusawa, R. Takizawa, N. Oguma, H. Hohjo, H. Ikuno, Development ofMulti-type High Efficiency Fatigue Testing Machines in Rotating Bending and Axial
Loading, Proceedings of the Hael Mughrabi Honorary Symposium, TMS Annual Meeting,(2008), 241-246.

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