Validity requirements for fracture toughness measurements obtained from small circumferentially notched cylindrical specimens
✍ Scribed by R.N. Ibrahim; H.L. Stark
- Publisher
- Elsevier Science
- Year
- 1987
- Tongue
- English
- Weight
- 487 KB
- Volume
- 28
- Category
- Article
- ISSN
- 0013-7944
No coin nor oath required. For personal study only.
✦ Synopsis
The authors have earlier proposed a small cylindrical circumferentially notched and fatigue cracked specimen for estimating K,, Finite element studies carried out are discussed with specific attention to the comparison between K,( thus obtained to that obtained experimentally. The size of the plastic zone is of particular interest in respect of the validity of the results; the F.E. result is compared to that obtained using Von Mises and Irwin approximations. Validity requirements are proposed for this specimen considering general yield of the final ligament, final ligament size. plastic zone size and depth of fatigue crack.
NOMENCLATURE
the critical plane strain stress intensity factor (MPaJm) specimen outside diameter (mm) tensile force appled to specimen at fracture (N) radius from the crack tip (mm) orientation from crack plane ahead of crack tip (Fig. 5) (<) constant describing specimen geometry (eq. 4) plastic zone correction (Irwin) (mm) crack depth. (machined notch + fatigue crack + r,) (mm) average axial stress in the final ligament at fracture (MPa) normal stresses in the coordinate directions s, r and :, (Fig. 2) (MPa) shear stresses in the coordinate directions X. J and Z. (Fig. 2) tensile yield strength of specimen material (MPa) Poisson's ratio (0.3 elastic. 0.5 plastic)