軸의 Keyway 附近에서의 應力集中現狀에 관한 硏究 = A Study on the Stress Concentration Phenomenon Near the Keyway of a Shaft

다국어 초록 (Multilingual Abstract)

The fatigue strength is decreased by stress concentration in the curvature part of a keyway. Thus, the stress concentration phenomena near the kewway of a shaft have been treated as an important issue. The objective of this thesis is to analyze stress concentration phenomena numerically by means of 3-Dimensional Finite Element Method and to examine fracture form near the keyway of a shaft by a torsional fatigue testing.
Stress concentration phenomena have been studied for various width, depth, and sled radius of the sled runner type key way of the shaft which is subjected to torsional moment. Torsional fatigue tests were carried out using PMMA bar specimen to examine the initiation and the form of fracture.
The following results were obtained.
1.. The maximum principal stress was appeared near the end corner portion of a sled part and the direction of the maximum principal stress was 45 degree with the axis of the shaft.
2. As the depth of the keyway is being increased, the stress concentration coefficient for the maximum principal stress which appeared sled part is increased. And as the width of the keyway or the radius of the sled is being increased, stress concentration coefficient is decreased.
3. The fracture of a low ductile shaft occurs at the point where the distortion energy density is greatest and the direction of fracture is 45 degree with the axis of the shaft by means of principal stresses. The fracture of a high ductile shaft occurs, however, in the dirction of 90 degree with the axis of the shaft by means of the maximum shear stress at the parallel portion of the keyway.