was performed to verify the validity of the derived spring con-

Table 1。 Comparison of spring constants between theoretical results and FEM results。

Thickness [mm] Diameter [mm] Spring constants [N。m/rad]

Equation Analysis Error ratio*

2。4 68。2 72。1031 72。1999 0。13

2。0 63。8 45。1770 45。6126 0。95

1。8 60。0 35。4755 35。9964 1。45

1。6 56。6 26。7706 27。2686 1。83

1。4 53。6 19。2010 19。6143 2。11

1。2 51。0 12。8843 13。1587 2。09

1。1 48。7 10。5388 10。8064 2。48

1。0 46。6 8。3959 8。5864 2。22

Spring Pack 230。5463 233。2433 1。16

* (Analysis – Equation) / Analysis × 100%

Fig。 9。 Experimental equipment。

Table 2。 Torsional torque according to rotation angle of inner star。

Working angle ( ) Trosional torque [N。m]

Degree Radian

0。0 0 0

0。2 0。0335 116。048

0。4 0。0070 234。920

0。6 0。0105 356。724

0。8 0。0140 481。570

1。0 0。0175 609。577

stant。 Fig。 7 shows the modeling and boundary conditions for obtaining spring constant of the sleeve spring。 The spring con- stant was obtained by piding the rotation angle into the ap- plied moment。 The rotation angle was obtained by converting deformation in the Y-direction, as shown in Fig。 8。 Table 1 summarizes a comparison of theoretical results and the FEA results for the spring constants。 [1]

The values of the theoretical results using the spring con- stant formula were always less than those of the FEM results, and the error between the theoretical results and the FEM was less than 2。48%, which indicated good agreement。 The error between the theoretical results and the FEM for the spring pack was 1。16%。 The torsional torque according to the    rota-

tion angle of the inner star was calculated by applying the values in Table 1 to Eq。 (3), as shown in Table 2。 In the result, the stiffness of the sleeve spring torsional vibration damper used in the MT881 Ka-550 engine was 609。4N。m/°。