Measurement of fracture toughness of miniature coupons from aging structures
- Univ. of California, La Jolla, CA (United States)
It is often necessary to assess the integrity of many major structures and their components which have been, and are, in service and hence, have aged. In particular, it may be necessary to assess the change in the fracture toughness of the material of the structural components as they age. In these situations, often only very small-size (miniature) samples may be available, on the basis of which an assessment of the fracture toughness needs to be made. Using UCSD`s novel recovery tension Hopkinson technique, we have developed a procedure to estimate the fracture toughness of miniature coupons, over a broad range of strain rates, from, say, a hundred to several thousand per second. In this technique a fatigue crack is first initiated at the tips of a small notch or a hole (1 mm in diameter), and then the coupon is subjected to a stress pulse of fully-controlled profile and energy content. Through high-speed photography (up to 2,000,000 frames/sec, 8 5 frames, 35mm film), crack initiation, growth, and arrest are recorded. In addition, the corresponding load and displacement of the coupon, as functions of time, are measured. The data thus allow obtaining estimates of the resistance to fracturing of the material and the average crack-growth velocity. We have complete control of the fracturing process, so that we are able to recover the sample before the cracks reach the free sides of the coupon. The width of the coupon can be 0.45 to 1.00 inch.
- OSTI ID:
- 175120
- Report Number(s):
- CONF-950686-; TRN: 95:006111-0029
- Resource Relation:
- Conference: Joint applied mechanics and materials summer meeting, Los Angeles, CA (United States), 28-30 Jun 1995; Other Information: PBD: 1995; Related Information: Is Part Of AMD - MD `95: Summer conference; PB: 520 p.
- Country of Publication:
- United States
- Language:
- English
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