scholarly journals Dynamic Analysis for Mechanical Systems with Multi-Degree of Freedom under Base Excitation Using Relative Acceleration

2020 ◽  
Vol 19 (3) ◽  
pp. 36-41
Author(s):  
Tae Won Lee ◽  
Keyword(s):  
Dynamic Analysis ◽  
Mechanical Systems ◽  
Degree Of Freedom ◽  
Base Excitation ◽  
Relative Acceleration

Design and Analysis of Folding Linkage Based on Five Functional Medical Bed

2010 ◽  
Vol 42 ◽  
pp. 9-12
Author(s):  
Guang Ping Zhang ◽  
Jian Bin Zhang
Keyword(s):  
Theoretical Analysis ◽  
Dynamic Analysis ◽  
Design Principle ◽  
Mechanical Systems ◽  
Degree Of Freedom ◽  
Optimal Structure ◽  
Future Research ◽  
Folding Mechanism ◽  
Driving Torque ◽  
At Home

Based on the simplex style of the traditional medical beds at home and abroad presently, a new folding mechanism of multifunctional medical bed was presented. After theoretical analysis, an optimal structure was selected. This mechanism consists of several planar four-bar linkages. It has one degree of freedom, which means it can be driven by only one driving torque to achieve multi-states changes. Therefore, it could save the space and reduce the weight of the bed as much as possible. The analysis of mechanism was carried out, simulation and stability were performed as well. A proto was established in the software named Automatic Dynamic Analysis of Mechanical Systems (ADAMS) to verify feasibility of the mechanism and the correctness of the design principle. It is an ingenious and brief design, which provides useful information for future research about folding medical bed.

scholarly journals Mobility Method Applied to Calculate the Lubrication Properties of Bearing under Dynamic Loads

2013 ◽  
Vol 2013 ◽  
pp. 1-5 ◽  
Author(s):  
Tao He ◽  
Xiqun Lu ◽  
Jingzhi Zhu
Keyword(s):  
Dynamic Analysis ◽  
Mechanical Systems ◽  
Journal Bearings ◽  
Numerical Results ◽  
Dynamic Loads ◽  
Analysis Program ◽  
Computational Program ◽  
Dynamically Loaded ◽  
Mobility Method ◽  
Lubrication Properties

The analytical mobility method for dynamically loaded journal bearings was presented, with the intent to include it in a general computational program, such as the dynamic analysis program, that has been developed for the dynamic analysis of general mechanical systems. An illustrative example and numerical results were presented, with the efficiency of the method being discussed in the process of their presentation.

scholarly journals An approach to quantify the influence of ground motion uncertainty on elastoplastic system acceleration in incremental dynamic analysis

2017 ◽  
Vol 20 (11) ◽  
pp. 1744-1756 ◽  
Author(s):  
Peng Deng ◽  
Shiling Pei ◽  
John W. van de Lindt ◽  
Hongyan Liu ◽  
Chao Zhang
Keyword(s):  
Dynamic Analysis ◽  
Ground Motion ◽  
Earthquake Engineering ◽  
Structural Response ◽  
Incremental Dynamic Analysis ◽  
Degree Of Freedom ◽  
Maximum Acceleration ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
Performance Based Earthquake Engineering

Inclusion of ground motion–induced uncertainty in structural response evaluation is an essential component for performance-based earthquake engineering. In current practice, ground motion uncertainty is often represented in performance-based earthquake engineering analysis empirically through the use of one or more ground motion suites. How to quantitatively characterize ground motion–induced structural response uncertainty propagation at different seismic hazard levels has not been thoroughly studied to date. In this study, a procedure to quantify the influence of ground motion uncertainty on elastoplastic single-degree-of-freedom acceleration responses in an incremental dynamic analysis is proposed. By modeling the shape of the incremental dynamic analysis curves, the formula to calculate uncertainty in maximum acceleration responses of linear systems and elastoplastic single-degree-of-freedom systems is constructed. This closed-form calculation provided a quantitative way to establish statistical equivalency for different ground motion suites with regard to acceleration response in these simple systems. This equivalence was validated through a numerical experiment, in which an equivalent ground motion suite for an existing ground motion suite was constructed and shown to yield statistically similar acceleration responses to that of the existing ground motion suite at all intensity levels.

A Method for Identifying Parameters of Mechanical Joints

1990 ◽  
Vol 57 (2) ◽  
pp. 337-342 ◽  
Author(s):  
J. Wang ◽  
P. Sas
Keyword(s):  
Physical Parameter ◽  
Mechanical Systems ◽  
Degree Of Freedom ◽  
Modal Testing ◽  
Physical Parameters ◽  
Mechanical Joints ◽  
Joint Parameters

A method for identifying the physical parameters of joints in mechanical systems is presented. In the method, a multi-d.o.f. (degree-of-freedom) system is transformed into several single d.o.f. systems using selected eigenvectors. With the result from modal testing, each single d.o.f. system is used to solve for a pair of unknown physical parameters. For complicated cases where the exact eigenvector cannot be obtained, it will be proven that a particular physical parameter has a stationary value in the neighborhood of an eigenvector. Therefore, a good approximation for a joint physical parameter can be obtained by using an approximate eigenvector and the exact value for the joint parameters can be reached by carrying out this process in an iterative way.

Accelerometer correction for the dynamic analysis of damped multi-degree of freedom systems

1969 ◽  
Vol 59 (4) ◽  
pp. 1591-1598
Author(s):  
G. A. McLennan
Keyword(s):  
Dynamic Response ◽  
Dynamic Analysis ◽  
Degrees Of Freedom ◽  
Degree Of Freedom ◽  
Exact Method ◽  
Three Degrees Of Freedom

Abstract An exact method is developed to eliminate the accelerometer error in dynamic response calculations for damped multi-degree of freedom systems. It is shown that the exact responses of a system can be obtained from the approximate responses which are conventionally calculated from an accelerogram. Response calculations were performed for two typical systems with three degrees of freedom for an assumed pseudo-earthquake. The results showed that the approximate responses may contain large errors, and that the correction developed effectively eliminates these errors.

Structural Analysis for Space-Swing Mechanism on Gyratory Compactor

2014 ◽  
Vol 621 ◽  
pp. 253-259
Author(s):  
Jing Qian ◽  
Ling Wei Meng
Keyword(s):  
Structural Analysis ◽  
Dynamic Analysis ◽  
Initial Phase ◽  
Mechanical Systems ◽  
Systems Software ◽  
Superpave Gyratory Compactor ◽  
Flexible Models

Based on the automatic dynamic analysis of mechanical systems software, both rigid and flexible models of the space-swing mechanism for the superpave gyratory compactor are developed. The structural analysis shows that the length and the initial phase of cranks, and the assembling accuracy (coordinates) of some points are very sensitive relative to the waving of compaction angle. Greater rigidity helps stabilize the change of the compaction angles.

On the Use of the Canonical Equations of Motion for the Dynamic Analysis of Constrained Multibody Systems

1992 ◽  
Author(s):  
E. Bayo ◽  
J. M. Jimenez
Keyword(s):  
Dynamic Analysis ◽  
Multibody Systems ◽  
Equations Of Motion ◽  
Mechanical Systems ◽  
Numerical Algorithms ◽  
Constrained Multibody Systems ◽  
Constrained Mechanical Systems ◽  
First Order ◽  
Canonical Variables ◽  
Lagrange’S Multipliers

Abstract We investigate in this paper the different approaches that can be derived from the use of the Hamiltonian or canonical equations of motion for constrained mechanical systems with the intention of responding to the question of whether the use of these equations leads to more efficient and stable numerical algorithms than those coming from acceleration based formalisms. In this process, we propose a new penalty based canonical description of the equations of motion of constrained mechanical systems. This technique leads to a reduced set of first order ordinary differential equations in terms of the canonical variables with no Lagrange’s multipliers involved in the equations. This method shows a clear advantage over the previously proposed acceleration based formulation, in terms of numerical efficiency. In addition, we examine the use of the canonical equations based on independent coordinates, and conclude that in this second case the use of the acceleration based formulation is more advantageous than the canonical counterpart.

Modeling of Flexible Bodies for Dynamic Analysis of Multi-Body Dynamic Systems Using Ritz Vectors

1991 ◽  
Author(s):  
Henry T. Wu ◽  
Neel K. Mani
Keyword(s):  
Dynamic Analysis ◽  
Mechanical Systems ◽  
Normal Modes ◽  
Flexible Bodies ◽  
Static Correction ◽  
Ritz Vectors ◽  
Regeneration Procedure ◽  
Efficient Vector ◽  
Multi Body ◽  
Body Dynamic

Abstract Vibration normal modes and static correction modes have been previously used to model flexible bodies for dynamic analysis of mechanical systems. The efficiency and accuracy of using these modes to model a system depends on both the flexibility of each body and the applied loads. This paper develops a generalized method for the generation of a set of Ritz vectors to model flexible bodies for dynamic analysis of multi-body mechanical systems. The Ritz vectors are generated using the distribution of dynamic loading on a flexible body. Therefore they form the most efficient vector basis for the spatial distribution of the loadings. The Ritz vectors can be re-generated when the system undergoes significant changes of its configuration and the regeneration procedure is inexpensive. The combinations of vibration normal modes and the proposed Ritz vectors thus form more efficient and accurate vector bases for the modeling of flexible bodies for dynamic analysis.

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