PREDIKSI PENJALARAN RETAK FATIK PADA POROS YANG DIKENAI BEBAN LENTUR AMPLITUDO KONSTAN

• Main Author: Akhyar
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/5205
• Institution: Institut Teknologi Bandung

<b>Abstract: <p align=\"justify\"> <br /> <br /> A crack on machine shafts can be effected by design, pabrication, assembling and operation error. At the crack tip of shaft surface usually attend a plastic zone. Then, if subjected to a external loading, crack will propagate so that shaft will be broken. <br /> This research was conducted to study the change of the stress intensity factor on the shaft surface with semi-elliptical crack geometry subjected to cyclic bending moment with constant amplitude. Beside that, this research also is to find a prediction model of fatigue crack growth, critical crack depth and fatigue life. This work is conducted by computer simulation and to verify the result a fatigue rotating bending experiment has been developed on the shaft specimens of AISI 1045 and A1-2024-T3 with 15 mm diameter. The pre-crack sizes was given 0.5 mm on the AISI 1045 shaft surface and 1.0 mm on the AI-2024-T3 shaft surface. <br /> The research result shows that shafts with semi-elliptical surface crack have a higher stress intensity factor by higher loadings. The trend of crack geometries change from semi-elliptical towards semi-circular which b/a ratio approaches 1.0 both steel and aluminium specimens. The simulation of critical crack depth and fatigue life can be predicted and have been be verification by experiment with accuracy of 89% and 92% respectively; or with a deviation of 8% and l0% for steel, and 11% and 10% for aluminium. The fractograph of specimen shows that fatigue failure consists of pre-crack, crack growth indicated by the present of beach mark, and final rupture.<p align=\"justify\"> <br /> <br />