• Title/Summary/Keyword: Spline Shaft Connection

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DDM Rotordynamic Design Sensitivity Analysis of an APU Turbogenerator Having a Spline Shaft Connection

  • Lee, An-Sung;Ha, Jin-Woong
    • Journal of Mechanical Science and Technology
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    • v.17 no.1
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    • pp.57-63
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    • 2003
  • An eigenvalue design sensitivity formulation of a general nonsymmetric-matrix rotor-bearing system is devised. using the DDM (direct differential method). Then, investigations on the design sensitivities of critical speeds are carried out for an APU turbogenerator with a spline shaft connection. Results show that the dependence of the rate of change of the critical speed on the stiffness changes of bearing models of spline shaft connection points is negligible, and thereby their modeling uncertainty does not present any problem. And the passing critical speeds up to the 4th critical speed are not sensitive to the design stiffness coefficients of four main bearings. Further, the dependence of the rate of change of the critical speed on the shaft-element length changes shows quantitatively that the spline shaft has some limited influence on the 4th critical speed but no influence on the 1st to 3rd critical speeds. With no adverse effect from the spline shaft, the APU system achieves a critical speed separation margin of more than 40% at a rated speed of 60,000 rpm.

Rotordynamics Design Sensitivity Analysis of an APU Gas Turbine having a Spline Shaft Connection (스플라인-축 연결을 갖는 보조동력장치 가스터빈의 로터다이나믹 설계민감도 해석)

  • Lee, An-Sung;Ha, Jin-Woong
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2000.11a
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    • pp.593-598
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    • 2000
  • In this paper the critical speed analysis and design sensitivity investigation are carried out with an APU(auxiliary power unit) gas turbine having a spline shaft connection. The DDM(direct differential method) is directly applied to formulate the critical speed design sensitivity problem of a general nonsymmetric-matrix rotor-bearing system. The design sensitivity analysis have shown that the critical speed change rate to the support modeling of the spline shaft connection point is extremely negligible, and thereby its design uncertainty is lifted. It has also been confirmed that the critical speeds up to the 4th are not sensitive to the design stiffness coefficients of 4-main bearings or supports, including two air foil bearings. Further, the critical speed change rate to the shaft-element length have shown quantitatively that the spline shaft has some limited influence on the 4th critical speed.

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Fatigue Life Estimation of Induction-Hardened Drive Shaft Under Twisting Loads (비틀림 하중을 받는 고주파열처리 드라이브 차축의 피로수명 평가)

  • Kim, Tae Young;Kim, Tae An;Han, Seung Ho
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.41 no.6
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    • pp.567-573
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    • 2017
  • The drive shaft of passenger vehicle has an important role in transmitting the torque between the power train system and the wheels. Torsional fatigue failures occur generally in the connection parts of the spline edge of the drive shaft, when there is significant fatigue damage under repeated twisting loads. A heat treatment, an induction hardening process, has been adopted to increase the torsional strength as well as the fatigue life of the drive shaft. However, it is still unclear how the extension of the induction hardening process in a used material relates to its shear-strain fatigue life range. In this study, a shear-strain controlled torsional-fatigue test with a specially designed specimen was conducted by an electro-dynamic torsional fatigue test machine. A finite element analysis of the drive shaft was carried out using the results obtained by the fatigue experiment. The estimated fatigue life was verified through a twisting load test of the real drive shaft in a test rig.

A Study on the Corrosion Prevention of the Integral Series Generator for Military Vehicles (군용차량용 엔진일체형 직렬 발전기 부식 방지에 관한 연구)

  • Kang, Tae-Woo;Kim, Seong-Gon;Shin, Cheol-Ho;Lee, Kye-Sub
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.20 no.6
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    • pp.74-79
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    • 2019
  • The military vehicle produces electric power through an engine-integrated serial hybrid generator that is connected to the engine and does not have a separate generator installation space. However, depending on the mechanical characteristics of the connection between the generator and the engine, iron oxide for internal rusting and lubrication grew scattered. The iron oxide is adhered to the starter to deteriorate the starting performance, and there is a problem that the noise of the leg due to wear of the gear is increased. To solve this problem, the connection spline material and the surface treatment of the engine were improved and the shape was changed to a grease sealing type to prevent the generation of iron oxide inside. As the shape of the generator connector composing the shafting system was changed, the integrity of the structure was confirmed through the torsional endurance test. In addition, through the actual vehicle load test, it was verified that no corrosion occurred during the target life span without internal corrosion. It was confirmed that the anti-scattering structure of the grease effectively suppresses the generation of iron oxide, thereby reducing the noise generated from the generator. In this paper, we propose a fundamental solution to the degradation of the starter and the noise generation by preventing the back corrosion caused by the serial hybrid generator installed between the engine and the transmission.