Fracture Surface Topography Analysis

SRI has developed a new technology that analyzes failures in materials and structures to disclose when cracks nucleated and how fast they grew. The technology, called FRASTA (Fracture Surface Topography Analysis), is a major advance in fractography that allows a failure event to be replayed in microscopic detail. Besides providing mechanistic and microstructural information not obtainable from conventional fracture surface examination, FRASTA can often provide the history of a crack and the fracture toughness of the material.

FRASTA can provide the understanding of failure in components required to develop lifetime predictive capability for new or in-service systems and provide earlier warning of impending failure. Furthermore, the improved knowledge of degradation processes in aging components is expected to lead to new ways to extend life and new techniques for inspecting a component's health.

For example, when FRASTA was applied to a part-through crack in a 22-year-old boiler tube in a fossil fuel power plant, we determined that the crack nucleated after 68,000 hours of operation and that acceleration and deceleration phases of crack growth occurred during plant operation. We were able to determine the crack growth rate during the entire operation and correlate changes in crack growth with chemical cleanings and hot starts. Such information can be used to alter the operation and maintenance conditions of the plant to extend plant life and set more realistic inspection schedules to ensure safe plant operation.

1. Readiness of Defense structures is determined bu mechanical damage from service and aging.
2. Cracks propagate by microstructural failure in the highly stressed process zone at the crack tip.
3. Deformation and microfailure in the process zone are manifested as roughness features on the fracture surfaces.
4. SRI's FRASTA technique provides a fast way to make accurate topographical maps of the fracture surfaces and software to analyze the data.
5. A crack propagation event can be reconstructed in microstructural detail.
6. FRASTA provides previously unobtainable data on deformation and microfailure, nucleation, growth and coalescence in the process zone.
7. Damage evolution rates will enable health monitoring and readiness

FRASTA GENERATED ELEVATION VIEW OF A GROWING CRACK

FRASTA GENERATED PLAN VIEW OF A GROWING CRACK

Contact Us
Don Shockey
Director, Center for Fracture Physics
Phone: 650-859-2587
Email: donald.shockey@sri.com