Page 65 - Shimadzu Dynamic and Fatigue Testing Systems

For Evaluating Fatigue Strength at Cycle Level of Fatigue Strength of SNCM439(B) Steel
10 or Higher 1100 SNCM439(B)
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C. Masuda et al.
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Conventionally, it was assumed that fatigue strength of steel was constant beyond 10 cycles. In 1000 Rotating bending,50Hz
other words, it was assumed that fatigue failure would not occur at stresses below the fatigue Properties of SNCM439(B) Steel
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limit for 10 cycles. However, we are now learning that in the case of materials strengthened by 900 f Yield stress: 1444 MPa
Tensile strength: 1870 MPa
quenching or surface treatment, internal inclusions can cause fatigue fractures between 10 and Stress amplitude, S(MPa) f f Vickers hardness: 592 Hv EHF Series Electric Hydraulic Dynamic and Fatigue Testing System
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9
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10 cycles even for stress levels below the 10 fatigue limit. f
Therefore, now that products are being used for longer periods at higher speeds, fatigue 800 f f
fractures between 10 and 10 cycles have become an extremely important issue. f
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9
700
Fracture at stresses below
Allows tests of 10 cycles to be completed in only six days, the 10 7 cycle fatigue limit f: Fracture from internal
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defect
which would normally take 3.2 years at 100 Hz. 600
1.0x10 4 1.0x10 5 1.0x10 6 1.0x10 7 1.0x10 8 1.0x10 9 1.0x10 10
Number of cycles, N
Example of the fatigue
For Analyzing Inclusions in Test Materials fracture surface of
high-strength steel
In high-strength steels and other materials, fatigue can propagate from micro defects fractured by the Shimadzu
USF-2000 Ultrasonic
and inclusions inside the material, which are known to result in fatigue fractures at the Fatigue Testing System
gigacycle level. Therefore, identifying and analyzing defects and inclusions in test
materials are useful for developing materials with high fatigue strength. Inclusion where the fatigue
fracture originated can be
Due to the extremely small size of such defects and inclusions, they are very dif cult to identi ed
identify using non-destructive methods. Typically, materials were sliced and the section
surface visually inspected. EMT/NJ-SERVO/MMT Series Electric Fatigue and Endurance Test System
However, the ef ciency of identifying and analyzing inclusions can be increased
dramatically by using an ultrasonic fatigue testing machine to the point of fatigue
fracture, which ensures a defect or inclusion will be discovered on the fracture surface.
Example of Sample Dimensions (given Young's modulus of 206,000 MPa and density of 7.85 g/cm 3 )
Circular Tapered Sample Notched Sample
M6×0.75 (6.49)
M6×0.75 R3.0
Ø 3.0 (R58.9) Ø10.0 Ø 6.0

90° Ø10.0
40±0.05
60.75±0.05 Servo Controller 4830 Controller for Dynamic and Fatigue Testing Systems
9.8±0.05 9.8±0.05
121.5±0.05
Test stress range: About 200 to 1000 MPa nominal Test stress range: About 140 to 700 MPa nominal
Stress concentration factor: About 1.56 Units: mm

Specifications
Test frequency 20 kHz ±500 Hz (recommended test range: 20 kHz ±30 Hz) Note: The test frequency is determined from the resonance frequency of the sample.
Vibration at horn tip ±10 to ±50 m
Test stress range Stress given ±10 to ±50 m displacement of sample Note: Stress values depend on sample shape and physical property values.
Stress ratio -1
Materials that can be resonated at 20 kHz and generate minimal heat during resonance
Testable materials
Example: High-strength steel, duralumin, titanium alloy, aluminum, etc.
Materials that cannot resonate at 20 kHz
Materials for which samples are difficult to attach
Not-testable materials Materials that generate significant heat during resonance at 20 kHz, due to friction
Examples: Resins, ceramics, etc.
Power requirements 3-phase 200 V: 2 kVA (air compressor) , 1-phase 200V: 3.5 kVA (ultrasonic fatigue testing system) , 1-phase 100V: 1 kVA (computer, displacement logger, air dryer, etc.)
USF-2000A Ultrasonic Fatigue Testing System main unit (including table), ultrasonic resonance system, control computer, Various Dynamic Testing Systems
Standard contents ultrasonic testing control and measurement software, and cooling unit (air dryer and compressed air lines)
Note: Air compressor for cooling is not included.
Air compressor (for regions with 50 Hz or 60 Hz power) 3-phase 200 V: 2 kVA
Displacement measuring system (eddy current displacement gauge with 0.5 m resolution)
Required optional products
Note: A high-speed data logger or digital oscilloscope is required separately for reading voltages output from the displacement gauge.
Displacement gauge calibrator (CDE-25 C1 high-performance micrometer)
Note: Systems can be selected without an air compressor in cases where the customer will supply the compressed air. A 150 L/m ow rate of compressed air at a minimum 0.2 MPa is required.

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