Tooth Stress Redistribution to Improve Bending Fatigue Strength of Spur-Gear
Samer A. Masoud Al-Said
Associate Professor
Mechanical Engineering Department, Jordan University of Science and
Technology
(Currently visiting associate professor at King Saud University Riyadh
Saudi Arabia)
P.O. Box 3030, Irbid 22110-Jordan
e-mail: masoud@just.edu.jo
Mohammad Qasim
Former Graduate Student
Mechanical Engineering Department, Jordan University of Science and
Technology
P.O. Box 3030, Irbid 22110-Jordan
ABSTRACT
Two techniques based on stress redistribution are proposed to reduce
the bending fillet stress of spur gear. In the first method, drilling
circular holes through gear face near the tooth fillet will reduce the
original maximum stress. In the second method, introducing pressurized
hole near tooth fillet creates compressive stress field that will
cancel part of the original tooth tensile stresses. Reductions up to
4.24% and 5.42 % of the maximum Von Mises stress at the root fillet of
the tension side (RFTS) are achieved in the first and the second method
respectively. Applying both methods to spur gear with small crack at
RFTS leads to similar results of the un-cracked spur gear. Computer
code utilizing boundary element method is developed to calculate gear
stresses. Also, an optimisation method is applied to the proposed
techniques to find the optimum fillet stress reduction. Using
Commercial finite element analysis code will verify the obtained
results.
