Dynamic Tensile Testing Using a Three-Dimensional DIC Analysis System —Observation of Strain Distribution and Measurement of Strain in Polypropylene Just before Fatigue Failure—

Previously, it was often difficult to predict the appropriate fatigue life during fatigue testing that applied dynamic test forces or strains at high speeds due to stress concentration in the areas measured with conventional strain measurement methods that use contact-type sensors. For this reason, in recent years, analysis by digital image correlation (DIC) has attracted attention as a testing technique that can be used to accurately evaluate the static and dynamic mechanical characteristics of materials in the elastic and plastic ranges. The fatigue characteristics of such materials can now be comprehensively evaluated by installing a three-dimensional DIC analysis system in the fatigue and durability testing machine.

Fatigue DIC Analysis Example

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  Principal Strain-Time Diagrams
  (Virtual Strain Gauge Measurement)

In-Plane Principal Strain Distribution (Confirmation of Strain Concentration Locations)
Note: The virtual strain gauge is a function included in the DIC analysis software that can measure displacement at any arbitrarily specified point on the sample observation surface.

• Enables detailed evaluation of in-plane strain during the fatigue failure process.
• Data is continuously acquired during the measurement time of one fatigue test cycle, so the strain distribution can be evaluated during hysteresis.
• Enables fatigue evaluation from peak-to-peak data acquisition.

 

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  Test Sample and Jigs
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  Comparison of Stress-Strain Curves
  (Comparison of Strain Gauge and Virtual Strain Gauge)

 In-Plane Principal Strain Distribution

 

This system can also be used for static tensile testing.