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Fracture Toughness Testing

Fracture toughness testing
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Fracture toughness is a key input for a fitness-for-service assessment. In some industries fracture mechanics tests are generally known as 'CTOD (crack tip opening displacement) testing', although most current standard methods permit CTOD, J and K to be determined from the fracture toughness test. CTOD tests are increasingly being performed as part of weld procedure qualification. However, fracture toughness testing is more complex than other 'standard' mechanical tests, such as tensile or Charpy tests.

On the one hand fracture toughness tests are considered to be increasingly routine, requiring faster turnaround test times. Also, variations to high-constraint fracture toughness test specimens tested in air are being sought, such as SENT (single edge notch tension) tests, tests in sour environments, or full-scale pressure tests.

On the other hand, TWI's involvement with standards committees, fracture research, our testing capabilities for  bespoke tests, large-scale tests, pressure tests, and  sour/environmental tests means we can accommodate almost any request for non-standard fracture mechanics testing too.

Find out more about TWI’s fracture testing laboratories here

The originators of the CTOD test

We offer a competitive fracture toughness testing service. As the organisation that invented the CTOD test, TWI offers unique knowledge of standard fracture toughness tests, and in particular, the ability to interpret and provide advice when the results are complex (such as fitting tearing resistance curves, analysis of pop-ins, explaining low results or why tests may not fully meet qualification criteria, and whether that means the data can or cannot be safely used).

We can also offer training in fracture toughness testing.

Our express testing service for standard types of fracture mechanics specimen can provide results as test certificates with fast turnaround.

Where there are more complex requirements, such as SENT tests, R-curves, post-test metallography, ECA (engineering critical assessment) or other analysis, the work is performed as a project managed by a fracture expert to report the results, interpretations and analysis of the data.

Fracture Toughness Testing enquiry form

To assist with creating fracture toughness testing requirements you can quickly send details and specifications using our enquiry form:

Fracture Toughness Testing enquiry

For general enquiries you can also email us on

For more information please email: