Plane Strain Fracture Toughness Testing

Applied Technical Services offers plane strain fracture toughness testing in accordance with ASTM E399.  Plane strain fracture toughness, or KIC, measures a material’s resistance to crack extension in conditions where there is minimal plastic deformation. The stress-intensity factor (K) is a function of structural geometry, crack size, and loading, while KIC determines a material’s fracture toughness independent of the abovementioned factors.

Why is Fracture Toughness Testing Important?

Fracture toughness testing provides insight into the stress needed to propagate preexisting flaws in a material. Flaws such as cracks, weld defects, and design discontinuities occur throughout the materials’ production and service life, so manufacturers must evaluate the toughness of materials to determine their best application. Failure to inspect materials may result in abrupt failure, expensive repairs, and safety concerns as there may be unaddressed and unseen flaws propagating within a material.


ASTM E399 tests pre-cracked specimens using three-point bending or tension loading to determine their plane strain fracture toughness. The standard evaluates the relationship between the stress applied to a material and the length of the surface crack by subjecting the sample to a continuously increasing load.

During the procedure, samples with preexisting cracks endure cyclic loading, causing crack propagation. Our experts record the stress and load at which the failure and observe the crack propagation to evaluate the material’s mechanical properties, including the material’s threshold for brittle cracking and tearing.

More About Our Mechanical Testing Lab

In addition to plane strain fracture toughness testing, our A2LA-accredited mechanical testing lab offers various testing and analysis services that assist in failure analysis and material qualification. Our engineers evaluate materials and determine their structural integrity through tensile, hardness, fatigue, and impact tests. Our staff works with clients to develop testing procedures that align with the demands of their service requests to ensure that our services satisfy their needs.

About Applied Technical Services

Applied Technical Services provides professional consulting engineering, inspection, and testing services to clients worldwide. In our 55 years of business, we have expanded our operation into an extensive list of services that benefit various industries, including:

Please submit a web request form or call + 1 (888) 287-5227 for additional details regarding our plane strain fracture toughness testing services.

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