• International Journal of Precision Engineering and Manufacturing
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• v.3 no.2
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• pp.61-71
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• 2002

This paper presents the dynamic analysis of indeterminate rotor systems with angular contact ball bearings subject to axial and radial loads. The reaction forces against applied radial loads significantly influence the dynamic characteristics of angular contact ball bearings. However, the reaction forces are hard to determine in the case of indeterminate rotor-bearing systems. To this end, this paper proposes a finite element model for indeterminate rotor systems with angular contact ball bearings. An improved bearing model is adopted which is originated from the Harris's bearing dynamic model. The bearing model is also extended to include centrifugal forces due to the ball and inner ring. This paper utilizes a new iterative algorithm for general, indeterminate rotor systems with angular contact ball bearings. This examples are provided to illustrate the dynamic characteristics of rotor systems with angular contact ball bearings subject to axial and radial loads. The experimental and numerical results prove that the proposed method is useful for the dynamic analysis of indeterminate rotor systems with angular contact ball bearings.

• Proceedings of the KSME Conference
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• 2001.11a
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• pp.67-72
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• 2001

The LBB behavior and the crack opening displacement after a crack penetrated wall thickness of statically indeterminate piping system were investigated in this study, compared with statically determinate piping system. The reduction of ultimate strength caused by a crack was relatively small in the statically indeterminate piping system. The statically indeterminate piping system has more safety margin for LBB behavior than the statically determinate piping system. The crack opening displacement could be evaluated by using the plastic rotation angle proposed to evaluate the crack opening displacement after crack penetration in pipe with a non-penetrating crack.

• Tribology and Lubricants
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• v.10 no.1
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• pp.62-68
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• 1994

The analysis of statically indeterminate bearing-shaft system was investigated. The moment loads and misalignment angles which were induced in the ball bearings were determined, and the influence of span length of this system on the moment loads and fatigue lives was identified. The sliding and spinning speeds between balls and raceways which affected the performance of ball bearing evaluated. The equation to estimate the cage speed of ball bearing under moment loads was proposed. This equation had been verified by the test results of measuring of cage speed, which was useful to the prediction of ball bearing under moment loads.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1993.12a
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• pp.70-76
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• 1993

From the analysis of shaft-bearing indeterminate system, moment and misalingment angle which was generated in bearing were determined. And the influence of span length between bearings on the fatigue life was established. The equation to estimate the cage rotational speed was proposed, and this equation was verified by the measuring of cage speed and shaft speed. And accoding to quasi-static analysis, the spinning speed of ball was determined.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.6
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• pp.725-730
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• 2010

The leak-before-break behavior and the crack opening displacement were investigated of statically indeterminate piping system and statically determinate piping system after a crack penetration. The reduction in the ultimate strength caused by a crack was relatively small in the statically indeterminate piping system. The leak-before-break in the statically indeterminate piping system had a larger safety margin than that in the statically determinate piping system. The crack opening displacement after crack penetration in a pipe with a nonpenetrating crack was evaluated by using a plastic rotation angle.

• Architectural research
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• v.3 no.1
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• pp.71-80
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• 2001

It is quite difficult to calculate the collapse probability of a system such as statically indeterminate structure that has many possible modes or paths to complete failure and the problem has remained essentially unsolved. A structure is synthesized by several components or elements and its capacity to resist the given loads is a function of the capacity of the individual element. Thus it is reasonable to assess the probability of failure of the system based upon those of its elements. This paper proposes an efficient technique to directly assess the reliability of a complex structural system from the reliabilities of its components or elements. The theory for the calculation of the probability of a structural system is presented. The target requirements of the method and the fundamental assumptions governing the method are clearly stated. A portal frame and two trusses are selected to demonstrate the efficiency of the method by comparing the results obtained from the proposed method to those from the existing methods in the literature.

• Transactions of the Korean Society of Mechanical Engineers
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• v.12 no.4
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• pp.675-681
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• 1988

A simplified FRF(frequency response function) model of an indeterminate cantilever system with viscoelastic material layers is derived. A way to calculate modal damping of the system from the dynamic properties of the viscoelastic material is proposed. The model is experimentally verified.

• The korean journal of orthodontics
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• v.26 no.3
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• pp.281-290
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• 1996

Determination of force system and prediction of side effects from unbent straight wire engaged in edgewise bracket is clinically very difficult because it is statically indeterminate system. This study is to develop a linear beam theory that explains the force system for straight wire engaged in edgewise bracket regardless of geometry(a/b), material, cross section of wire, and interbracket distance. 1. Formula for force system of bilateral fixed end beam was derived. 2. It is possible to calculate force system of each tooth engaged in continuous straight wire. 3. The possibility and location of permanent deformation can be predicted.

• Journal of The Korean Society of Agricultural Engineers
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• v.57 no.6
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• pp.59-68
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• 2015

Traditional structure analysis method is based on numerical matrix analysis to use the geometries consisting of the structure. The characteristics require a lot of computer memories and computational time. To avoid these weaknesses, new approach to analyze truss structure was suggested by adopting topological load redistribution method. The axial forces to be not structurely analyzed yet against outside loads were redistributed by using nodal equation of equilibrium randomly at each node without constructing global matrix. However, this method could not calculate the axial forces if structure is statically indeterminate due to degree of many indeterminacies. Therefore, to apply the method suggested in this research, all redundancies of truss structure were replaced by unit loads. Each unit load could make the deformation of a whole structure, and a superposition method was finally adopted to solve the simultaneous equations. The axial forces and deflections agreed with the result of commercial software within the relative error of 1 %, whereas in the case that the axial forces are relatively very smaller than others, the relative errors were increased to 2 %. However, as the values were small enough not to be considered, it was practically useful as a structural analysis model. This model will be used for structural analysis of truss type of large structure such as agricultural farming facility.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.59-64
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• 2003

The parameter modification of the initial FEM model to match it with the experimental results needs the modal information and the modal sensitivity matrix to the parameter change. There are two cases this methodology is ill-equip to deal with; the deficiency of the necessary modal information and the ill-conditioning of the sensitivity matrix. In this research, a novel concept of the feedback exciter that uses the summation of the white noise and the signals from the measurement sensors multiplied with feedback gains as the reference signal is proposed. There are 2 advantages using this external feedback excitation. First, we can use the change of the system response such as modal data by the active energy Path from the sensor to the exciter. This change of the system response can be additional clues to the system dynamics that we want to know. Secondly, the external energy Path alternates the offset of the Parameter change to the system response. That means the modal sensitivity of the parameters becomes different from the original sensitivities by the feedback excitation. Through the feedback loop, we can change the similar modal sensitivities of some updating parameters and consequently discriminate the parameters using the closed-loop modal data. To demonstrate the discrimination performance, the parameter estimation of an indeterminate structure by use of the feedback method is introduced.