Papers by Keyword: Pendulum

Abstract: This paper presents the characteristics of damping force and energy regeneration of a pendulum. The damping force analysis includes force-displacement and force velocity loops when the pendulum, attached in a cart, is subjected with sinusoidal displacement input. The energy regeneration analysis includes the voltage, the current and the power generated by a generator. The main objectives of this paper are to obtain the mathematical models and to characterize both force and energy regeneration based on the inputs. The results show that the amplitudes and the frequencies at low level are most likely basic damper behavior. Moreover, the energy regeneration increases as well as the amplitude and the frequency.

Abstract: Dynamic simulations of structures to determine their seismic performance is an essential part of civil engineering research. Time integrators of increasing sophistication has been elaborated over the last few decades to achieve higher order accuracy, unconditional stability, computational efficiency and high-frequency dissipation. This paper tries to extend 1-stage Rosenbrock-based integrator to an integrator of second-order accuracy without losing computational efficiency and unconditional stability. Initially, 1-stage Rosenbrock integrator is introduced and its order of accuracy is studied theoretically. According to accuracy analysis, a force term at the end of current step is considered, resulting a novel integrator of second-order accuracy. Moreover, the stability of the proposed method is studied by means of the energy method. To investigate its performance for nonlinear structures, numerical simulations are conducted on a shear-type structure including a pendulum.

Abstract: A new type of spherical robot based on the concept of changing the barycenter of the system is presented. The robot is consist of a shell and inner driving unit inside. The driving motor can provide the torque to move forward and backward, and the other motor can control the movement of a slider which is used to change the barycenter when turning the direction. The whole system is easy to design and the plate inside can be installed with certain sensor for special tasks. The dynamic model of the robot is introduced. The simulation results which shows the accordance with the experiment is presented.

Abstract: The efficiency analysis of wave energy collection and conversion is crucial for utility of wave energy of inverse pendulum. In the paper, we build the hydrodynamic model of interaction between pendulum and wave in wave energy converter of inverse pendulum. On the basis of this typical model, we choose the actual wave condition of some sea area in the east of China as the background, research the hydrodynamic property of pendulum by numerical simulation with fluent software, get the relation curve of between the rotation angle of pendulum and moment of wave force with time, and acquire energy conversion model from wave energy to mechanical energy in wave energy converter of inverse pendulum. It makes the beneficial exploration for optimal design of wave energy converter of inverse pendulum.

Abstract: The paper developed a pendulum impact testing machine. The impact testing machine is mainly used for dynamic mechanical properties testing and anti-destructive testing for the steering assembly. The mechanical system of testing machine adopts the impact type of pendulum acceleration of gravity. It adopts optical-electricity encoder to control the pendulum angle of oscillation. The movement of the pendulum is controlled by gear reducer motor and clutch. The curve of the impact force changing along with the time is half-sine wave during the whole process.

Abstract: Impact test of shipboard systems must be taken before navy ships take service. Only in this way can we ensure the safety and reliability of them. In middle-weight high impact testing machine which is one of main devices to test medium weight equipments, pendulum is the most important as well as the most perishable part of this machine. Good quality of pendulum should be ensured. Energy demands, reliability, service life and deformation of the pendulum must be taken into account when design pendulum of this tester part. An optimization methods to design pendulum is presented in this paper. By means of optimization of the position of mass centre, percussion centre and impact point, the reliability and service life of pendulum can be improved.

Abstract: Collision impulse to pendulum shaft is tend to be generated when hammer impacting the anvil. In order to eliminate the collision impulse and find a preferential size of the pendulum, based on the rigid body dynamical model, the conditions of the coincidence of the center of strike and the center of percussion are established; calculation formula of the distance between the axis of the pendulum shaft and the center of percussion is derived. By selecting certain geometric parameters of the pendulum as design variables and transferring the multi-objective nonlinear optimal design problem into single objective problem, a mathematical model of the optimal design of the pendulum is established. Matlab optimization toolbox is utilized to calculate the model, and a reasonable result is obtained. The work of this paper has considerable significance in the far field of engineering design.

Abstract: The present paper is a generalization of the problem of a rubber spring pendulum discussed by Bhattacharyya in 2000 and Stănescu in 2011, which studied the case of the neo-Hookean rod without mass. In our paper we consider that the mass of the neo-Hookean rod is not negligible and its deformation is realized such that at any moment of time the rod can be treated as a homogeneous rigid bar of variable length. Using the second order Lagrange equations we obtained the equations of motion in the most general case and we identified as particular cases the situations presented in the bibliography. We also performed a study of the equilibrium positions and their stability. A study of the small oscillations about the stable equilibrium positions is realized too. The theoretical results are finally compared to those obtained by numerical simulation.

Abstract: Based on the analysis of pendulum, the period formulas and dynamic model of asymmetric pendulum were explored, the effects of the release heights and the distances (the following known as nail distances) between two nails on the vertical on the period of asymmetric pendulum were analyzed and tested, we studied period differences on the condition that the asymmetric pendulum was released from different sides of the vertical. The test results indicate that the period of asymmetric pendulum decreases gradually with the increasing of nail distances under the same release heights condition and the asymmetric pendulum has the same period when the pendulum is released from different sides of the vertical under the condition of the same nail distances and the same release heights.

Abstract: The requirements for evaluating the mechanical characteristics of materials have increased in the various industrial, research and the applications such as materials testing. Therefore, the authors have proposed a method for measuring force acting a material using pendulum [1]. In the Material tester, the mechanical characteristics of material against small force are measured by means of the pendulum mechanism based on the levitation mass method (LMM) [2,3,4].In the LMM, the Doppler shift frequency is measured for measuring the inertial force. The Doppler shift frequency of a laser beam reflected from the mass is accurately measured by using optical interferometer. The velocity, position, acceleration and inertia force of the mass are calculated from the measured time-varying Doppler shift frequency. Thus, the accurate measure of frequency makes that of force.