How broken is broken? Crack tip opening displacement testing

Even the strongest and hardest-working materials on earth—pipes, drills, munitions, girders—crack. A crack is the beginning of failure, but when and how dramatically will the failure occur?

The world demands more—greater quantities of energy, taller buildings, longer pipelines, faster and higher-flying aircraft. Material scientists have responded with stronger and more durable metals, but every one, given the right set of circumstances, will crack.

Crack Tip Opening Displacement (or CTOD) is one of a family of fracture mechanics tests that measures the resistance of a material to crack growth, (or failure). Stork Southwestern Laboratories acquired CTOD capabilities to provide better data for their customers who use the thickest, strongest metals in their businesses, such as the oil and gas industry. Similar tests (with names like da/DN, K1C, KEE, and J1C) can determine fracture resistance of a material, but CTOD is particularly suited to pipeline and drilling equipment.

Stork scientists using CTOD data can predict the growth rate of a fracture, giving clients the information they need to select the best possible material and take the best possible course of action at the best possible time. Testing provides “critical defect assessment” data, virtually the precise point—in time and space—at which a crack or other flaw must be controlled. This information is extremely valuable to clients making material, financial, insurance, production, staffing and safety decisions based on the condition and demands of their equipment.

Read our white paper on CTOD: Crack Tip Opening Displacement: Using Materials Testing to Control Cracks