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1 – 10 of 553
Article
Publication date: 1 March 1989

Mallikarjuna and Tarun Kant

A C° continuous finite element higher‐order displacement model is developed for the dynamic analysis of laminated composite plates. The displacement model accounts for…

Abstract

A C° continuous finite element higher‐order displacement model is developed for the dynamic analysis of laminated composite plates. The displacement model accounts for non‐linear distribution of inplane displacement components through the plate thickness and the theory requires no shear correction coefficients. Explicit time marching schemes are adopted for integration of the dynamic equilibrium equation and a diagonal ‘lumped’ mass matrix is employed with a special procedure applicable to Lagrangian parabolic isoparametric elements. The parametric effects of the time step, finite element mesh, lamination scheme and orthotropy on the transient response are investigated. The effect of the coupling on the transient response is also investigated. Numerical results for deflections and stresses are presented for rectangular plates under various boundary conditions and loadings and compared with results from other sources.

Details

Engineering Computations, vol. 6 no. 3
Type: Research Article
ISSN: 0264-4401

Article
Publication date: 1 March 2006

Guo‐Ping Cai and Jia‐Zhen Hong

In this paper, a first‐order approximation coupling (FOAC) model is investigated to analyze the dynamics of the hub‐beam system, which is based on the Hamilton theory and…

Abstract

In this paper, a first‐order approximation coupling (FOAC) model is investigated to analyze the dynamics of the hub‐beam system, which is based on the Hamilton theory and the finite element discretization method. The FOAC model for the hub‐beam system considers the second‐order coupling quantity of the axial displacement caused by the transverse displacement of the beam. The dynamic characteristics of the system are studied through numerical simulations under twos cases: the rotary inertia of the hub is much larger than, and is close to, that of the flexible beam. Simulation and comparison studies using both the traditional zeroth‐order approximation coupling (ZOAC) model and the FOAC model shows that when large motion of the system is unknown, possible failure exists by using the ZOAC model, whereas the FOAC model is valid. When the rotary inertia of the hub is much larger than that of the beam, the result using the ZOAC model is similar to that using the FOAC model. But when the rotary inertia of the hub is close to that of the beam, the ZOAC model may lead to a large error, while the FOAC model can still accurately describe the dynamic hub‐beam system.

Details

Multidiscipline Modeling in Materials and Structures, vol. 2 no. 3
Type: Research Article
ISSN: 1573-6105

Keywords

Article
Publication date: 4 September 2009

A. Mahmoodi, M.B. Menhaj and M. Sabzehparvar

The purpose of this paper is to present an algorithm for inverse dynamics problem of a generally configured Stewart platform which is both fast and accurate.

Abstract

Purpose

The purpose of this paper is to present an algorithm for inverse dynamics problem of a generally configured Stewart platform which is both fast and accurate.

Design/methodology/approach

A Newton‐Euler approach is presented, using the advantage of body coordinate frames, instead of inertial ones in order to omit redundant matrix transformations.

Findings

The method is found to lead to an efficient algorithm for inverse dynamics of a generally configured Stewart platform, which is at least three times faster than the available algorithms. This algorithm is at the same time more accurate, due to considering the gyroscopic effects of rotary parts within the legs.

Originality/value

Utilizing body coordinate frames for both platform and legs (instead of inertial ones) and taking into account the gyroscopic effects of the rotary parts within the leg, are the innovative aspects of this paper. The more significant achievement of the presented method is the remarkably faster rate of convergence, which is very important in feedback linearization control.

Details

Aircraft Engineering and Aerospace Technology, vol. 81 no. 5
Type: Research Article
ISSN: 0002-2667

Keywords

Article
Publication date: 1 November 2006

Sumeet Pradhan and P.K. Datta

To study the effect of rocket mass and an intermediate mass on the critical flutter load of a free‐free beam (missile‐like structure).

Abstract

Purpose

To study the effect of rocket mass and an intermediate mass on the critical flutter load of a free‐free beam (missile‐like structure).

Design/methodology/approach

A finite element model of beam considering shear deformation and rotary inertia, based on Hamilton's principle applied to non‐conservative system.

Findings

Smaller geometric dimensions of the end rocket assist in the stability. Optimum positioning of the intermediate mass leads to stability.

Practical implications

The stability of free‐free missile structures can be better understood.

Originality/value

Sheds new light on the effect of rocket mass and an intermediate mass on the critical flutter load of a free‐free beam.

Details

Aircraft Engineering and Aerospace Technology, vol. 78 no. 6
Type: Research Article
ISSN: 0002-2667

Keywords

Article
Publication date: 28 June 2021

Mustafa Tolga Tolga Yavuz and İbrahim Özkol

This study aims to develop the governing differential equation and to analyze the free vibration of a rotating non-uniform beam having a flexible root and setting angle…

Abstract

Purpose

This study aims to develop the governing differential equation and to analyze the free vibration of a rotating non-uniform beam having a flexible root and setting angle for variations in operating conditions and structural design parameters.

Design/methodology/approach

Hamiltonian principle is used to derive the flapwise bending motion of the structure, and the governing differential equations are solved numerically by using differential quadrature with satisfactory accuracy and computation time.

Findings

The results obtained by using the differential quadrature method (DQM) are compared to results of previous studies in the open literature to show the power of the used method. Important results affecting the dynamics characteristics of a rotating beam are tabulated and illustrated in concerned figures to show the effect of investigated design parameters and operating conditions.

Originality/value

The principal novelty of this paper arises from the application of the DQM to a rotating non-uniform beam with flexible root and deriving new governing differential equation including various parameters such as rotary inertia, setting angle, taper ratios, root flexibility, hub radius and rotational speed. Also, the application of the used numerical method is expressed clearly step by step with the algorithm scheme.

Details

Aircraft Engineering and Aerospace Technology, vol. 93 no. 5
Type: Research Article
ISSN: 1748-8842

Keywords

Article
Publication date: 10 January 2020

Guangxin Wang, Lili Zhu, Ken Higuchi, Wenzhong Fan and Linjie Li

The purpose of this paper is to propose and analyze the free vibration response of the spatial curved beams with variable curvature, torsion and cross section, in which…

Abstract

Purpose

The purpose of this paper is to propose and analyze the free vibration response of the spatial curved beams with variable curvature, torsion and cross section, in which all the effects of rotary inertia, shear and axial deformations can be considered.

Design/methodology/approach

The governing equations for free vibration response of the spatial curved beams are derived in matrix formats, considering the variable curvature, torsion and cross section. Frobenius’ scheme and the dynamic stiffness method are applied to solve these equations. A computer program is coded in Mathematica according to the proposed method.

Findings

To assess the validity of the proposed solution, a convergence study is carried out on a cylindrical helical spring with a variable circular cross section, and a comparison is made with the finite element method (FEM) results in ABAQUS. Further, the present model is used for reciprocal spiral rods with variable circular cross section in different boundary conditions, and the comparison with FEM results shows that only a limited number of terms in the results provide a relatively accurate solution.

Originality/value

The numerical results show that only a limited number of terms are needed in series solutions and in the Taylor expansion series to ensure an accurate solution. In addition, with a simple modification, the present formulation is easy to extend to analyze a more complicated model by combining with finite element solutions or analyze the transient responses and stochastic responses of spatial curved beams by Laplace transformation or Fourier transformation.

Details

Engineering Computations, vol. 37 no. 5
Type: Research Article
ISSN: 0264-4401

Keywords

Article
Publication date: 31 January 2020

Mahdi Shayanmehr and Omid Basiri

In this paper, the important aspects of vibration analysis of carbon nanotubes (CNTs) as nano-resonators are studied. This study has covered the important nonlinear…

Abstract

Purpose

In this paper, the important aspects of vibration analysis of carbon nanotubes (CNTs) as nano-resonators are studied. This study has covered the important nonlinear phenomena such as jump super-harmonic and chaotic behavior. CNT is modeled by using the modified nonlocal theory (MNT).

Design/methodology/approach

In previous research studies, the effects of CNT’s rotary inertia, stiffness and shear modulus of the medium were neglected. So by considering these terms in MNT, a comprehensive model of vibrational behavior of carbon nanotube as a nanosensor is presented. The nanotube is modeled as a nonlocal nonlinear beam. The first eigenmode of an undamped simply supported beam is used to extract the nonlinear equation of CNT. Harmonic balance method is used to solve the equation, while to study its super-harmonic behavior, higher-order harmonic terms were used.

Findings

In light of frequency response equation, jump phenomenon and chaotic behavior of the nanotube with respect to the amplitude of excitation are investigated. Also in each section of the study, the effects of elastic medium and nonlocal parameters on the vibration behavior of nanotube are investigated. Furthermore, parts of the results in linear and nonlinear cases were compared with results of other references.

Originality/value

The present modification of the nonlocal theory is so important and useful for accurate investigation of the vibrational behavior of nano structures such as a nano-resonator.

Details

World Journal of Engineering, vol. 17 no. 1
Type: Research Article
ISSN: 1708-5284

Keywords

Article
Publication date: 1 January 1961

H.L. Cox

The free and harmonically forced flexural vibrations of missiles accelerating along initial trajectories are considered. A general matric formulation is given for the…

Abstract

The free and harmonically forced flexural vibrations of missiles accelerating along initial trajectories are considered. A general matric formulation is given for the problem whereby the effects of variable inertial axial loads along the missile length, variable stiffness and material properties, variable mass, variable mass moment of inertia, variable shear stiffness, and variably distributed forcing functions are treated. The matric formulation of the problem is in standard eigenvalue form and no special coding will be required for organizations that currently are solving eigenvalue problems on electronic digital computers. The time required for an engineer to fill in the matrices of the basic matric equation governing the vibrations of a missile structure is quite small since only fundamental data are needed and almost all calculations are performed within the computer.

Details

Aircraft Engineering and Aerospace Technology, vol. 33 no. 1
Type: Research Article
ISSN: 0002-2667

Article
Publication date: 1 August 2004

Dick Bloss

Recent National Manufacturing Week Show in Chicago highlighted many new innovations. Assembly system designers can choose from new low inertia drives, more compact linear…

Abstract

Recent National Manufacturing Week Show in Chicago highlighted many new innovations. Assembly system designers can choose from new low inertia drives, more compact linear and rotary motors, innovative robots and pneumatic actuators along with new modular structural components which were featured at the show and in other recent introductions.

Details

Industrial Robot: An International Journal, vol. 31 no. 4
Type: Research Article
ISSN: 0143-991X

Keywords

Article
Publication date: 1 March 2006

Ratnakar S. Udar and P. K. Datta

To predict the occurrence of the combination resonances in parametrically excited, simply supported laminated composite plates in contrast to the simple resonances by…

Abstract

Purpose

To predict the occurrence of the combination resonances in parametrically excited, simply supported laminated composite plates in contrast to the simple resonances by using first‐order shear deformation lamination theory considering the effects of shear deformation and rotary inertia.

Design/methodology/approach

Finite element technique is applied to obtain the equilibrium equation of a plate. Modal transformation is applied to transform the equilibrium equation into a suitable form for the application of the method of multiple scales (MMS). The MMS is applied to obtain the boundaries of the simple and combination resonances.

Findings

The combination resonance zones contribute a considerable amount to the local instability region and the widths of combination resonance zones are comparable to those of the simple resonance zones for the loading of the small bandwidth at one end or for the concentrated edge loading.

Practical implications

Aircrafts, spacecrafts and many other structures such as ships, bridges, vehicles and offshore structures use the plate type elements, which are susceptible to dynamic instability.

Originality/value

It will assist the researchers of stability behavior of elastic systems.

Details

Aircraft Engineering and Aerospace Technology, vol. 78 no. 2
Type: Research Article
ISSN: 0002-2667

Keywords

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