Experimental Study of the Effect of Wire Electrical Discharge Machining on Crack tip Opening Displacement for Compact Tension Specimens of Low Carbon Steel
Pages: 58 - 71
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Participants:
Sara A. Khudair |
Atheed H. Taha |
Ameen A. Nassar |
Summary:
Fracture mechanics approach is important for all mechanical and civil projects that might involve cracks in metallic materials
the purpose of this paper is to determine a crack tip opening displacement fracture toughness experimentally, also study the
effect of thickness on CTOD fracture toughness of low carbon steel and study the effect of Wire Electrical Discharge Machine
(WEDM) to have a pre-crack, instead of fatigue pre-crack by using a CT specimen of low carbon steel with a thickness of
(8,10, and15 mm), a width of 30mm, crack length of 15mm, and pre-crack of 1.3mm for all samples, this dimension according
to ASTM-E399-13, by pulling the specimen in a 100 KN universal testing machine at a slow speed rate of 0.5 mm/min, the
load applied on the specimen is generally a tension load. The crack tip plastically deforms until a critical point PC at this
moment a crack is initiated. The computer-controlled universal testing machine gives the value of the load and the
displacement transducer gives a crack mouth opening displacement. Critical crack tip opening displacement CTOD is found
with the plastic hinge model (PHM) method. The result showed the stress intensity factor KI increases with increased loading
in the elastic region and the thickness effect refers to the effect of the plastic zone at the crack tip on the stress intensity factor,
In a thin specimen, a plastic zone is large at the fracture tip leads to a high-stress intensity factor at the fracture tip but in the
thick specimen, on the other hand, has a small a plastic zone and a low-stress intensity factor around the crack tip. The fracture
toughness is found to increase with an increase in the thickness of specimens.