Parallel Calculation of Random Vibration for Reentry Vehicles in Fluctuating Pressure Environment

The reentry vehicle is in an unconstrained free-flight state during the reentry process. The pressure of air fluctuations acts on the external surface of the vehicle and induces a random vibration environment with a wide-frequency range, which makes great influences on the structural dynamic properties of vehicles. This paper aims at the parallel calculation of the wide-frequency random vibration problems for the free body under multipoint fluctuating pressure loads. The calculation method is based on the self-developed JAUMIN framework and PANDA platform. The novel algorithm based on the modal superposition method reduces the computational complexity, realizes the parallel calculation, and achieves the maximum numerical simulation calculation capacity of 1.045 billion degrees of freedom (DOFs) while improving the calculation efficiency and the accuracy of the results. Finally, this article also uses typical examples to verify the correctness and parallel scalability of algorithms and programs.

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Modal Superposition Method for Computationally Economical Nonlinear Structural Analysis

Journal of Pressure Vessel Technology ◽

10.1115/1.3454612 ◽

1979 ◽

Vol 101 (2) ◽

pp. 134-141 ◽

Cited By ~ 21

Author(s):

V. N. Shah ◽

G. J. Bohm ◽

A. N. Nahavandi

Keyword(s):

Seismic Analysis ◽

Equations Of Motion ◽

Test Problems ◽

Superposition Method ◽

Structural Dynamic ◽

Large Wave ◽

Modal Superposition ◽

Nonlinear Structural ◽

Direct Integration Method ◽

Modal Superposition Method

A modal superposition method for analyzing nonlinear structural dynamic problems involving impact between components is developed and evaluated. The finite-element method is used to express the equations of motion with nonlinearities represented by pseudo force vector. Three test problems are solved to verify this method. This has demonstrated the applicability of this method to seismic analysis of large, complex structural systems. It is concluded that the modal superposition method has a significant cost advantage over the direct integration method for problems with large wave fronts and the source of nonlinearities restricted to a limited portion of the structure.

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Multi-Degrees of Freedom System and Hydrodynamic Principle

Structural Dynamics and Static Nonlinear Analysis From Theory to Application - Advances in Civil and Industrial Engineering ◽

10.4018/978-1-7998-4399-3.ch003 ◽

2021 ◽

pp. 81-142

Keyword(s):

Degrees Of Freedom ◽

Degree Of Freedom ◽

Superposition Method ◽

Modal Superposition ◽

Damped System ◽

Modal Superposition Method ◽

Hydrodynamic Study

A system with one degree of freedom is far from reality, because we do not take into account all the degrees of freedom. In order to be close to the reality, it is necessary to use a system with several degrees of freedom. Efforts in this chapter are concentrated to the study of multi-degrees of freedom system, whether for a free undamped and forced damped system, by detailing the modal superposition method as well as a coupled coordinates. We finish the chapter with hydrodynamic study using Hozner method as well as some applications.

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Design, Fabrication, and Testing of a Novel 3D 3-Fingered Electrothermal Microgripper with Multiple Degrees of Freedom

Micromachines ◽

10.3390/mi12040444 ◽

2021 ◽

Vol 12 (4) ◽

pp. 444

Author(s):

Guoning Si ◽

Liangying Sun ◽

Zhuo Zhang ◽

Xuping Zhang

Keyword(s):

Degrees Of Freedom ◽

Dynamic Properties ◽

Three Dimensional ◽

Polyimide Film ◽

Zebrafish Embryos ◽

Multiple Degrees Of Freedom ◽

Electrothermal Actuator ◽

3D Space ◽

Pick And Place

This paper presents the design, fabrication, and testing of a novel three-dimensional (3D) three-fingered electrothermal microgripper with multiple degrees of freedom (multi DOFs). Each finger of the microgripper is composed of a V-shaped electrothermal actuator providing one DOF, and a 3D U-shaped electrothermal actuator offering two DOFs in the plane perpendicular to the movement of the V-shaped actuator. As a result, each finger possesses 3D mobilities with three DOFs. Each beam of the actuators is heated externally with the polyimide film. The durability of the polyimide film is tested under different voltages. The static and dynamic properties of the finger are also tested. Experiments show that not only can the microgripper pick and place microobjects, such as micro balls and even highly deformable zebrafish embryos, but can also rotate them in 3D space.

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Designing of Drive Systems in the Aspect of the Desired Spectrum of Operation

Energies ◽

10.3390/en14092562 ◽

2021 ◽

Vol 14 (9) ◽

pp. 2562

Author(s):

Tomasz Dzitkowski ◽

Andrzej Dymarek ◽

Jerzy Margielewicz ◽

Damian Gąska ◽

Lukasz Orzech ◽

...

Keyword(s):

Degrees Of Freedom ◽

Dynamic Properties ◽

Dynamic Parameters ◽

Synthesis Algorithm ◽

Moments Of Inertia ◽

Driving System ◽

Six Degrees Of Freedom ◽

Resonance Frequencies ◽

Drive Systems ◽

Power Component

A method for selecting dynamic parameters and structures of drive systems using the synthesis algorithm is presented. The dynamic parameters of the system with six degrees of freedom, consisting of a power component (motor) and a two-speed gearbox, were determined, based on a formalized methodology. The required gearbox is to work in specific resonance zones, i.e., meet the required dynamic properties such as the required resonance frequencies. In the result of the tests, a series of parameters of the drive system, defining the required dynamic properties such as the resonance and anti-resonance frequencies were recorded. Mass moments of inertia of the wheels and elastic components, contained in the required structure of the driving system, were determined for the selected parameters obtained during the synthesis.

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OMA Study on the Structural Dynamic Properties of a Launcher Vehicle Using Flight Data

58th AIAA/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference ◽

10.2514/6.2017-1827 ◽

2017 ◽

Author(s):

Marco Eugeni ◽

Giuliano Coppotelli ◽

Franco Mastroddi ◽

Paolo Gaudenzi ◽

Stephan Muller ◽

...

Keyword(s):

Dynamic Properties ◽

Structural Dynamic ◽

Flight Data

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Structural Shape Reconstruction of FBG Flexible Plate Using Modal Superposition Method

Volume 8: 29th Conference on Mechanical Vibration and Noise ◽

10.1115/detc2017-67316 ◽

2017 ◽

Author(s):

Li Li ◽

Ben S. Zhong ◽

Zi Y. Geng ◽

Wei Sun

Keyword(s):

Mode Shape ◽

Shape Reconstruction ◽

Displacement Sensor ◽

Superposition Method ◽

Flexible Plate ◽

Structural Shape ◽

Modal Superposition ◽

Displacement Mode ◽

Modal Superposition Method ◽

Strain Data

Structural shape reconstruction is a critical issue for real-time structural health monitoring in the fields of engineering application. This paper shows how to implement structural shape reconstruction using a small number of strain data measured by fiber Bragg grating (FBG) sensors. First, the basic theory of structural shape reconstruction is introduced using modal superposition method. A transformation is derived from the measured discrete strain data to global displacement field through modal coordinate, which is the same for strain mode shape superposition and displacement mode shape superposition. Then, optimization of the sensor layout is investigated to achieve the effective reconstruction effect. Finally, structural shape reconstruction algorithm using modal superposition method is applied in experiments. The experiment results show that the reconstructed displacements match well with those measured by a laser displacement sensor and the proposed approach is a promising method for structural shape reconstruction.

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Structural dynamic properties of pentahaptocyclopentadienylmetal dicarbonyl dimers

Inorganic Chemistry ◽

10.1021/ic50110a001 ◽

1972 ◽

Vol 11 (4) ◽

pp. 671-676 ◽

Cited By ~ 90

Author(s):

J. G. Bullitt ◽

F. A. Cotton ◽

T. J. Marks

Keyword(s):

Dynamic Properties ◽

Structural Dynamic

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Effects of distributed structural dynamic modification with reduced degrees of freedom

Mechanical Systems and Signal Processing ◽

10.1016/j.ymssp.2009.03.014 ◽

2009 ◽

Vol 23 (7) ◽

pp. 2154-2177 ◽

Cited By ~ 8

Author(s):

Huajiang Hang ◽

Krishna Shankar ◽

Joseph C.S. Lai

Keyword(s):

Degrees Of Freedom ◽

Structural Dynamic ◽

Structural Dynamic Modification ◽

Dynamic Modification

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Seismic Analysis of Structures With Coulomb Friction

Journal of Pressure Vessel Technology ◽

10.1115/1.3264260 ◽

1983 ◽

Vol 105 (2) ◽

pp. 171-178 ◽

Cited By ~ 2

Author(s):

V. N. Shah ◽

C. B. Gilmore

Keyword(s):

Rigid Body ◽

Coulomb Friction ◽

Seismic Event ◽

Seismic Analysis ◽

Equations Of Motion ◽

Relative Displacement ◽

Rigid Body Motion ◽

Body Motion ◽

Superposition Method ◽

Modal Superposition Method

A modal superposition method for the dynamic analysis of a structure with Coulomb friction is presented. The finite element method is used to derive the equations of motion, and the nonlinearities due to friction are represented by pseudo-force vector. A structure standing freely on the ground may slide during a seismic event. The relative displacement response may be divided into two parts: elastic deformation and rigid body motion. The presence of rigid body motion necessitates the inclusion of the higher modes in the transient analysis. Three single degree-of-freedom problems are solved to verify this method. In a fourth problem, the dynamic response of a platform standing freely on the ground is analyzed during a seismic event.

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