Search | Korea Science

Yeo, Hong-Tae;Choi, Young;Hur, Kwan-Do
- Journal of the Korean Society for Precision Engineering
- /
- v.16 no.6
- /
- pp.114-122
- /
- 1999
By using the FEM, a method for the stress analysis of the presented dies has been proposed. In this method, FEM and Lame equation are used for the analysis of the die insert and the stress ring, respectively. The proposed method includes the calculation of the contact pressure between the die insert and the stress ring. To show the validity, the proposed method has been applied to the simple test problem. The results of the stress analysis have been compared with the results of ANSYS, a commercial FE-code. Cold extrusion has been simulated by using the rigid-plastic FEM and the results of the deformation analysis have been used as the input of the die structure analysis. The stress states of the prestressed extrusion die have been obtained. The stress analysis of the die insert with stress rings has also been performed during extrusion.
PDF

Kim, Dae-Seung;Kim, Jin-Oh
- Transactions of the Korean Society for Noise and Vibration Engineering
- /
- v.16 no.1 s.106
- /
- pp.89-100
- /
- 2006
This paper presents an analytical approach to describe the variation in the vibration characteristics such as the natural frequency of a piezoelectric transducer under static pre-pressure. The transducer considered in this paper is a bolt-clamped Langevin-type transducer, which consists of a couple of piezoelectric discs, a couple of metal blocks for added mass effect, and a bolt to tighten them. A new analysis model for the transducer has been developed by taking into account the contact area between the piezoelectric ceramic disc and the metal block. The variation of the resonance frequency due to the pre-pressure has been calculated and compared with measured results reported earlier.
https://doi.org/10.5050/KSNVN.2006.16.1.089 인용 PDF KSCI

Park, Jong-Won;Kim, Hyoung-Eui;Kim, Jong-Ock;Sim, Yang-Jin;Jung, Won-Wook
- Transactions of the Korean Society of Mechanical Engineers A
- /
- v.34 no.9
- /
- pp.1161-1166
- /
- 2010
Tapered roller bearings are core components of rotating machine parts and are simultaneously subjected to axial and radial loads. Life-shortening effect was particularly evident in the case of tapered roller bearings used in the input and output shafts of transmission; this shortening of life was a result of excessive axial pre-load, which is common in the transmission assembly line. In this study, we derived an equation for evaluating the life of tapered roller bearings subjected to excessive pre-load by using accelerated life test data. The DOE(Design Of Experiment) method and FEA(Finite Element Analysis) was used for determining the condition for performing an accelerated life test. This equation for evaluating the service life of the bearings was derived by analyzing the Weibull distribution of the test results. Using the derived equation the life evaluated was 6-7 times longer than that evaluated by the conventional $L_{10}$ bearing-life equation. The results of this study will be helpful in predicting the life of tapered roller bearings subjected to excessive pre-load and in designing reliable rotating machines.
https://doi.org/10.3795/KSME-A.2010.34.9.1161 인용 PDF KSCI