The presence of notches in engineering components generally weakens these components and leads to a reduction in their operational life. I order to ensure safety and reliability, It is necessary to be able to predict the role of the notches in governing the strength and fracture characteristics.
In this research, specimensmade of some structural alloys have been tested to determine the fracture resistance of these alloys under static loading and in the presence of sharp notches. Notched and un-notched specimens were made of ductile and grey cast irons in addition to data taken previously on high strength aluminum alloy of type 7075 and brass. Both ductile and grey cast Irons were manufactured in the foundary workshop of Mahalla Spinning and Weaving company.
Test results show that the reduction in the fracture resistance for the tested alloys depends on whether the alloy Is ductile or bottle. Ductile cast iron which is known to exhibit ductile behaviour showed low sensitivity to notching where bolted reduction in the fracture strength occured due to the presence of sharp notches. Crey cast Iron being a brittle material the other hand, experienced severe reduction in the fracture strength. Experimental points for the four structural alloys are seen generally to follow closely expected behaviour for ductile and bottle and brittle materials.
This behaviour has been expressed mathematically by an empirical formula.