Accuracy Of Dynamic Analysis Research Articles

Dynamic analysis and rotation experiment of an optical-trapped microsphere in air.

A dual-fiber optical trap system to trap and rotate a borosilicate microsphere has been proposed and experimentally demonstrated. The trapping system can be used as a probe to measure environmental parameters, such as torque, force, and viscosity of the surrounding medium. Under various conditions with different fiber misalignments, optical power, and fiber separation, the trapped sphere will exhibit three motion profiles including random oscillation, round rotation, and abnormal rotation. The power spectrum analysis method is used to measure rotation rates up to 385Hz, which can be further increased by increasing laser power. In addition, simulation and experiment show consistent results in rotation rates and motion trajectory, which verifies the validity and accuracy of dynamic analysis.

Accuracy Assessment of Pseudo-Rigid-Body Model for Dynamic Analysis of Compliant Mechanisms

Dynamic characteristics analysis is very important for the design and application of compliant mechanisms, especially for dynamic and control performance in high-speed applications. Although pseudo-rigid-body (PRB) models have been extensively studied for kinetostatic analysis, their accuracy for dynamic analysis is relatively less evaluated. In this paper, we first evaluate the accuracy of the PRB model by comparing against the continuum model using dynamic simulations. We then investigate the effect of mass distribution on dynamics of PRB model for compliant parallel-guided mechanisms. We show that when the beam mass is larger than 10% of the motion stage, the error is significant. We then propose a new PRB model with a corrected mass distribution coefficient which significantly reduces the error of the PRB model. And the dynamic responses are also analyzed according to the corrected mass distribution coefficient. At last, a compliant double parallel-guiding mechanism is used as a case study for validation of the new PRB model for dynamics of compliant mechanisms.

An Explicit Dynamic Method of Rigid Bodies-Spring Model

The rigid bodies-spring model (RBSM) has been developed as a numerical model to generalize limit analysis in plasticity, in which the structure to be analyzed is idealized as an assemblage of rigid bodies connected by normal and tangential springs. Originally, this approach was a discrete model for handling static problem. In this paper, we illustrate the formulation of an explicit dynamic method for each element using the principle of hybrid-type virtual work. Additionally, we propose a new RBSM approach for contact mechanism and friction characteristics. Finally, we verify the accuracy of dynamic analysis by RBSM with some numerical examples.

Multi-Objective Robust Active Vibration Control of an Arbitrary Thick Piezolaminated Beam

A multi-objective mixed / robust output feedback control synthesis with additional regional pole placement constraints in a linear matrix inequalities (LMI) framework is adopted for active vibration suppression of a simply supported, arbitrary thick, piezolaminated beam with continuously integrated sensor and actuator layers, in the face of high frequency unmodeled dynamics (residual uncertainties) and external disturbance. The structural formulation is based on a spatial state-space approach using the exact linear two-dimensional piezoelasticity theory and involving local/global transfer matrices. To assist control system design, subspace-based multivariable system identification is carried out by using the first four modes in the frequency range of 0–4000 rad/sec for control purpose, while the remaining high frequency (residual) modes in the control bandwidth are left as the uncertainty of modeling. The dynamic performance of vibration control system is demonstrated in both frequency and time domains for a three-layered sandwich beam including three pairs of piezoelectric actuator/sensor (Ba2NaNb5O15/PZT4) segments asymmetrically collocated on both sides of an orthotropic core for two different types of loading (i.e., impulsive load and random disturbance). The accuracy of dynamic analysis is established with the aid of a commercial finite element package and the data available in the literature.

Active vibration control of an arbitrary thick smart cylindrical panel with optimally placed piezoelectric sensor/actuator pairs

Active vibration suppression of a simply supported, arbitrarily thick, transversely isotropic circular cylindrical host panel, integrated with spatially distributed piezoelectric actuator and sensor layers, is investigated based on the linear three dimensional exact piezo-elasticity theory. To assist control system design, system identification is conducted by applying a frequency domain subspace approximation method based on N4SID algorithm using the first few structural modes of the system. The state space model is constructed from system identification and used for state estimation and development of control algorithm. The optimal electrode configuration for the collocated piezoelectric actuator–sensor pair is found by applying a genetic optimization procedure based on maximization of a quantifiable objective function considering the controllability, observability and spillover prevention of the identified system. A linear quadratic Gaussian (LQG) optimal controller is subsequently designed and simulated based on the identified model of optimally configured smart structure in order to actively control the system response in both frequency and time domains. The dynamic performance and effectiveness of the optimized vibration control system is demonstrated for two different types of external mechanical excitations (i.e., impulsive load and white noise disturbance). The accuracy of dynamic analysis is established with the aid of a commercial finite element package and the data available in the literature.

Dynamic analysis and control design of optocoupler-isolated LLC series resonant converters with wide input and load variations

Off-line power supplies for consumer or industrial electronics frequently encounter substantial changes in both input voltage range and load current requirement. This study presents theoretical and practical details involved with the dynamic analysis and control design of LLC series resonant dc-to-dc converters operating under wide input and load variations. The accuracy of dynamic analysis and validity of control design are confirmed with both computer simulations and experimental measurements.

Development of Simple Articulated Human Models using Superquadrics for Dynamic Analysis

Objective: This study is aimed at developing Articulated Human Models(AHM) using superquadrics to improve the geometric accuracy of the body shape. Background: The previous work presents the AHM with geometrical simplification such as ellipsoids to improve analysis efficiency. However, because of the simplicity, their physical properties such as a center of mass and moment of inertia are computed with errors compared to their actual values. Method: This paper introduces a three steps method to present the AHM with superquadrics. First, a 3D whole body scan data are divided into 17 body segments according to body joints. Second, superquadric fitting is employed to minimize the Euclidean distance between body segments and superquadrics. Finally, Fee-Form Deformation is used to improve accuracy over superquadric fitting. Results: Our computational experiment shows that the superquadric models give better accuracy of dynamic analysis than that of ellipsoid ones. Conclusion: We generate the AHM composed of 17 superquadrics and 16 joints using superquadric fitting. Application: The AHM using superquadrics can be used as the base model for dynamics and ergonomics applications with better accuracy because it presents the human motion effectively.

An Analytical Expression of Motion Equations of SSI System

The soil-structure interaction (SSI) effect is paid more and more attention in the dynamic structural analysis and earthquake resistance protection. However, theoretical analysis of SSI effect cannot accord with engineering applications because the analysis of SSI system is too complicated to be studied with a comprehensive theoretical basis. In order to promote the accuracy of dynamic analysis of SSI system in theory, in this paper, an analytical expression of motion equations of SSI system is given based on the concept of the continuity of dynamic system. In addition, mechanical models of SSI system on the basis of the continuity of motion domains are built and the analytical expression of equations of SSI system is given.

Dynamic analysis of shrouded blades and disc coupling system with freely slipping shroud contact surfaces

Discusses the application of the fixed interface modal synthesis technique and the quasi‐ periodically symmetric feature of the shrouded blades and disc system for analysing the coupling vibration characteristic of a system which has freely slipping contact surfaces. This technique has led to the establishment of an entirely new dynamic analysis method. With this method, the scale of calculation required has been greatly reduced, relieving the demand on CPU time and storage capacity while still ensuring sufficient accuracy of dynamic analysis.