CTOD Test (Crack Tip Opening Displacement Test)

The CTOD test is a fracture toughness test when some plastic deformation can occur before fracture, focusing on the stretching and opening of the tip of a crack, hence the displacement of the tip opening.

Crack Tip Opening Displacement, or CTOD, is a measure of the crack length or physical opening of the fatigue crack tip formed at the fracture point. The CTOD test measures the strength of cracked materials before they break and records the value at which crack formation begins.

Test Standards are ISO 24306, ASTM E1820, ASTM E1290, ASTM E399, BS 7448 and other in-house method.

CTOD testing is typically observed with three types of errors.

1. In the specimen, fracture is observed in the elastic region or shortly after the onset of deformation.
2. In the specimen, fracture is observed as the force continues to increase after crack formation has started.
3. Fracture occurs if the specimen cannot hold the applied load any longer and an unstable crack occurs.

The CTOD Test is a test that allows us to see the fracture mechanics of the material and determines the resistance of the material to the propagation of the crack. The test is performed by examining the notch previously opened on the test sample, a measuring device connected to this notch, and the progression of the crack as a result of the bending. During and after the test, it is observed how far the crack has progressed and how it progresses.

The main purpose of the test is not whether the material will crack under a certain load, but how long it will take for the crack to be critical after the crack is detected, and which method will be appropriate for crack detection.

EUROLAB Laboratory can help you with CTOD tests.