Preliminary Study of Using Kerf as a Crack Arrestor in a Plate Under Tension Loading

Abstract

There are few methods that are available for arresting cracks in fracture mechanics such as the use of fastening additional material and stop-hole. Another potential method that could be further developed is by using a kerf to be fabricated parallel to a crack. An earlier study about the use of a kerf as a kerf-crack interaction proved that the presence of the kerf would be able to reduce the stress intensity factor of the crack tip. Therefore, this research is exploring the possibility of using kerf as a crack arresting method. This research focuses on the fatigue test of a specimen that contains an edge crack and an edge kerf in a finite plate under fatigue tension loading. Two types of specimens to differentiate between long and short crack were prepared and tested according to the ASTM standard. The kerf on the specimen was fabricated using wire cut electrical discharge machine with a wire diameter of 0.25 mm. The fatigue test results of the crack growth rate versus the stress intensity factor range, (K were compared with the specimen that only contains an edge crack. The presence of the kerf parallel to the edge crack under tension loading, increased the fatigue cycles requiring additional 3000 cycles to grow the crack from 5.6 mm to 8.9 mm. The presence of the kerf also reduced the fatigue crack growth rate at the early stage i.e for (K less than 19 MPa√m. This indicates that the kerf has good potential as crack arresting method. A similar trend can be observed in the case of shorter crack and kerf. However, the effect is lesser than for the case of longer crack and kerf because the generated kerf-crack interaction is lower when shorter crack and kerf are used. A further study would be required to discover its accurate dimension, configuration and limitation as a crack arresting method.
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