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Absolute nodal coordinate formulation can be used to represent large displacement and large deformation in flexible body analysis based on the concept of continuum mechanics. However, the analysis takes a long time because of the increase in the degrees of freedom at a nodal point. In this study, the analysis time was reduced by using non-dimensional variables for the time, length, and force to convert a dimensional equation of motion into a non-dimensional one. Revolute and spherical joint were used to obtain numerical solutions by applying the non-dimensional equation of motion of free-falling pendulum. The non-dimensional equation of motion was verified by comparing the solutions with the numerical solution obtained using a dimensional equation of motion. The motion of a flexible hose was predicted by using the absolute nodal coordinate formulation, and it was shown the efficiency of non-dimensional equation of motion. [ABSTRACT FROM AUTHOR]

The unwinding behavior of thin cable has been studied in textile engineering. Recently, J.W. Lee derived transient equations of motion for an unwinding cable. Thus, this paper discusses numerical simulations of unwinding behavior as compared to experiments. The cable unwinding system is modeled using cylindrical coordinates, and Hamilton's principle in an open system is used to represent the mass change of the cable in the control volume. In a transient equation of unwinding motion, the transient-state response is affected by twopoint boundary conditions, such as the guide-eyelet point and the lift-off point. In previous research, only the unwinding velocity at the guide-eyelet point defined the boundary. Here, a boundary condition at the lift-off point is also considered in the unwinding velocity along with the unwinding length of cable in the control volume. The results of this study show that transient equations of motion should be derived by considering angular acceleration because of time-varying angular velocity. [ABSTRACT FROM AUTHOR]

When a cable unwinds from a spool dispenser, the cable demonstrates transient nonlinear behavior that makes a balloon. A precise analysis of the unwinding behavior of a wound cable is necessary in the design of a spool dispenser. In this study, the steady and transient states of a thin cable unwinding from a cylindrical spool dispenser are analyzed. Simulation results are compared with experimental results to verify complex unwinding behavior, such as tangling. Transient analysis results are in good agreement with experimental results. However, the steady-state solution is not in good agreement with experimental results because nonlinear transient equations are transformed into steady-state equations with the time-dependent terms neglected. Many solutions according to numerous sets of tension forces and radial slopes at the guide eyelet are found in these time-dependent terms. Transient solutions are necessary in the design of a realistic and accurate spool dispenser. [ABSTRACT FROM AUTHOR]

The motion of a flexible hose connected to a mother ship continually changes according to the motion of the mother ship. In such a case, telecommunication lines protected by the hose can give rise to serious problems like cutting or connecting error. It is very important to accurately analyze and predict the motion of an underwater flexible hose, because large deformation motions of the hose in axial and normal directions determine the vehicle's driving conditions. In a realistic situation, it is difficult to carry out an experiment because the length of the hose is at least 10 m. Therefore, the behavior has to be predicted by computer simulation. In this paper, a mother ship was considered as a rigid body with six degrees of freedom driven at a specific rudder angle and surge propulsion velocity. And to model the flexible hose, absolute nodal coordinate formulation (ANCF) was adopted, whose formulation is accurate enough to express both the large deformation effect and various forms of behavior of the flexible hose. In ANCF, the concept of continuum mechanics is introduced to derive the tensile and bending stiffness of the hose. Hence, nonlinear effects of elastic forces can be considered more effectively. Fluid drag is also imposed, which has a significant effect on both the vehicle and the flexible hose. [ABSTRACT FROM AUTHOR]

In the field of ‘human vibration’, until now most frequency weighting functions have been derived from particular experiments whose subjects were only Western people. However, because of inherent differences (e.g., characteristic and shape of body parts, muscular and cellular tissue) between Western people and Asian people, frequency weighting function based on Asian people is required. An experiment was carried out to develop a frequency weighting function for the Korean people in vertical whole-body vibration, and to verify whether this weighting is acceptable in practical applications in comparison with ISO 2631-1. Ten male subjects of mean weight and height were tested for a posture similar to sitting in a passenger seat (footrest, upright and placement of the palms of hands on thighs, etc.) of a car. This experiment was performed using sinusoidal excitation in the range from 2 to 250 Hz, which was a combination of one-half and one-third octave bands at eight determined amplitudes. To guarantee the reliability and accuracy of the test, non-parametric statistics was adopted to resolve the fact that there was not enough of the sample. Furthermore, two methods were considered to make the frequency weighting function and equal sensation curves. The first method changes the amplitude at every fixed frequency, and the other assigns weighting values. Korean people showed the most sensitivity to vertical whole-body vibration at 6.3 Hz excitation, so much higher weighting factors than weighting factors of other frequencies must be assigned near that frequency. [ABSTRACT FROM AUTHOR]