13th International Conference on Fracture
June 16–21, 2013, Beijing, China

Development and Several Additional Performances of Dual-Spindle Rotating
Bending Fatigue Testing Machine GIGA QUAD
Taizoh Yamamoto1,*, Akio Kokubu1, Tatsuo Sakai2, Yuki Nakamura3
1Yamamoto Metal Technos Co. Ltd., 4-7 Setoguchi 2-chome, Hirano-ku, Osaka, 547-0034 Japan
2Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu, Shiga, 525-8577 Japan
3Toyota 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 have 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℃
and -150deg.C, (2) ‘fracture alarm unit’, and (3) ‘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 industrialsectors.
Keywords High temperature environmental testing unit, Low temperature environmental testing unit,
Fracture alarm unit, 2-step variable loading unit, multi-type rotating bending fatigue testing machine

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 isperformed 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 ofspecimens 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
Number of cycles to failure N f , cycles

1010

Figure 1. Typical example of fatigue test data for bearing steel in very high cycle regime-1-13th International Conference on Fracture
June 16–21, 2013, Beijing, 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 environmentoptions. 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

MotorCapacitanceCollet Chuck
Max LoadSpindle Speed
WeightSize
Spindle Number

YRB2000.2kw-4P
380V
φ2.5～1320kg x 4
3,150rpm
140kg
470x400x1050
2-2-YRB200L
0.4kw-4p
380V
φ2.5～2080kg x 4
3,150rpm
170kg
800x660x1100
2

13th International Conference on Fracture
June 16–21, 2013, Beijing, China

Collet nut

Specimen

SpecimenCollet nut
Outer
block

Outer
block
CounterCounter

SpringSpringWeight Weight

Figure 2. GIGA QUADYRB200Figure 3. GIGA QUADYRB200L

Hourglass type of specimen as shown in Fig.4 is accepted as a formal test piece. 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.

The shape and dimensions of the specimen

3. Support for environmental testing
3.1. High temperature environmental testing unit
In order to perform the rotating bending fatigue test at high temperature, a special chamber and a-3-

13th International Conference on Fracture
June 16–21, 2013, Beijing, China

temperature controlling system have been developed.
By using such an unit, one can carry out the fatigue test within a temperature range of room
temperature (RT) to 600deg.C. Accuracy of the temperature controlling is within  2deg.C. As
fatigue test data are distinctly affected by the testing temperature, it is important to perform thefatigue tests at the accurate temperature. In such a case, this unit is useful to obtain the correct S-N
property of the material at the definite temperature.
Specification
Temperature controlling range: room temperature to 600deg.C
Size of control panel box: 170mm x 220mm x 280mm
Specimen type : our standard specimen (φ10)
Power: AC100V 1set

Heat chamber

Figure 5.

3.2.

High temperature environmental testing unit

Low temperature environmental testing unit

A special unit to spray liquid nitrogen into the chamber has been developed to conduct the rotating
bending fatigue test at low temperature environment.
By using this unit, one can carry out the fatigue test within the temperature range of RT to-100deg.C with the accuracy of  5deg.C.
Specification
Temperature controlling range : -100 deg.C to room temperature
Size of control panel box : 170mm x 220mm x 280mm
Specimen type : our standard specimen (φ10)

3.3.

2-step variable loading unit

A special loading unit has been developed to perform the rotating bending fatigue test under thecondition of 2-step variable loading. Stress applied to the specimen is provided by suspending theappropriate weight in the structure of the machine. In this unit, 2-step loading is applied by lifting apart of weight with air cylinder periodically in testing. By setting any value of the weight and thelifting period, one can perform fatigue tests in a wide variety of the testing environments close toreal machines in the practical use.
-4-

13th International Conference on Fracture
June 16–21, 2013, Beijing, China

3.4.

Fracture alarm unit

A fracture alarm unit which can detect fracture of specimen and inform the fracture to researchers
via e-mail has been developed. In the case of fatigue test to obtain the S-N property, the test isrepeatedly conducted by using a lot of specimens. In some cases, stress is changed with a definite
time span in order to simulate the actual service loading. Since the fatigue life of each specimen has
a distinct scatter, it is impossible to know the fatigue life exactly before the fatigue test. Due to thisdifficulty, 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 tocheck the fatigue failure can be also reduced.

Figure 7.

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 was-5-13th International Conference on Fracture
June 16–21, 2013, Beijing, China

confirmed. 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] Sakai T. Review and Prospects for Current Studies on Very High Cycle Fatigue of Metallic
Materials for Machine Structural Use. Proc. of VHCF-4, Ann Arbor, MI, USA, (2007), 3-12.
[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 Very HighCycle Fatigue held in Kyoto/Kusatsu, Japan on 16-19 September, 2004, International Journal ofFatigue, 2006; 28: 1437.
[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, Journalof 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 invery 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, T. Furusawa, R. Takizawa, M. Nakajima, K. Shiozawa, N. Oguma, K. Okada, Y.
Ochi, A. Sugeta, N. Kawagoishi, A. Sakaida, H. Sakamoto, Development of Multi-type Fatigue
Testing Machine in Axial Loading and Some Fatigue Test Results on A Bearing Steel, Proceedingsof VHCF-3, (2004), 484-491.
[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.

-6-