THE EFFECT OF NOTCH ANGLES ON THE FRACTURE PARAMETERS OF ALUMINUM THREE POINT BEND SPECIMENS
Keywords:
Stress Intensity Factor, Compliance based approach, J-integral, Linear Elastic Fracture Mechanics, Elasto Plastic Fracture MechanicsAbstract
Stable Crack Growth in ductile materials like aluminum, occurs prior to instability. The instability happens at higher load than the crack initiation load. A usual design based on the crack initiation load may lead to an under utilization of the material. In order to realize the full potential of the material, it is better to characterize the stable crack growth. n this work, the effect of notch angle on the critical stress intensity factor KIc is investigated for aluminum 6061 grade. A standard three point bend test is carried out on a rectangular bar with notch angles 300, 450 and 600 on a servo hydraulic machine. The specimen is precracked under cyclic loads and later tested under monotonic non cyclic loads. American Standard for Testing of Materials (ASTM) guidelines were used to fabricate and experiment the specimens to determine the critical Crack Tip Opening Displacement (CTOD) values. Compliance based approach was used to compute the Elasto-Plastic Fracture Toughness, J integral at different Crack Mouth Opening Displacement(CMOD) values.
Downloads
References
Rice, J.R., “A Path Independent Integral and Approximation Analysis of Strain Concentration by Notches and Cracks”, ASME Journal of Applied Mechanics, 379-396, 1968.
Mourad. A.H.I, Alghafri. M.J., Abu Zeid. O.A., Maiti. S.K., Experimental investigation on ductile stable crack growth emanating from wire-cut notch in AISI 4340 steel, Nuclear Engineering and Design 235, 637–647, 2005.
Pirondi.A, Dalle Donne.C., Characterization of Ductile Mixed Mode Fracture with Crack-Tip Displacement Vector, Engineering Fracture Mechanics 68, 1385-1402, 2001.
Shih CF. Relationship between the J-integral and the crack tip opening displacement for stationary and extending cracks, Journal of Mechanics and Physics of Solids, 29, 305-26, 1981.
Merkle J.G., Corten H.T., J-Integral Analysis for the Compact Specimen Considering Axial Force as well as Bending Effects, Journal of Pressure Vessel Technology, Trans ASME, 96, 286-292, 1974.
Standard Test Method for Crack Tip Opening Displacement (CTOD) fracture toughness measurement ASTM, 1290-99, Philadelphia, 1999.
Kudari.S.K. and Kodancha. K.G., On the Relationship between J-Integral and CTOD for CT and SENB Specimens, Frattura ed Integrita’ Strutturale 6, 3-10, 2008.
Jacques H. Giovanola, Steven W. Kirkpatrick, James E. Crocker, Fracture of Geometrically Scaled, Notched Three-Point-Bend Bars of High Strength Steel, Engineering Fracture Mechanics 62, 291- 310, 1999.
Derbalin.G, “J-integral Estimation Procedures”, Journal of Pressure Vessel Technology, 105, 299-308, 1983
