scholarly journals An Improved C0 FE Model for the Sandwich Lattice Composite Panel

Polymers ◽  
2021 ◽  
Vol 13 (23) ◽  
pp. 4200
Author(s):  
Junqing Hong ◽  
Chunyan Shen ◽  
Weiqing Liu ◽  
Hai Fang ◽  
Laiyun Yang
Keyword(s):  
Degrees Of Freedom ◽  
Element Model ◽  
Design Tool ◽  
Composite Panel ◽  
Fe Model ◽  
Three Dimension ◽  
Plate Element ◽  
Analysis Model ◽  
Analysis And Design ◽  
Numeric Calculation

Combining the improved C0 plate element using high-order zigzag theories and the beam element degenerated from the plate element, a type of analysis model for the sandwich lattice composite panel was developed. Compared with the actual test results including the mid-span deflections and the surface sheet normal stresses, the outstanding of that method was presented through numeric calculation. The results showed that the model has great potential to become an excellent and highly efficient analysis and design tool for sandwich lattice composite panel to avoid the conventional three-dimension hybrid element model, which usually may lead to the complex program establishment, and the coupling degrees of freedom among the different types of elements.

scholarly journals Wind-Induced Vibration Control of Dalian International Trade Mansion by Tuned Liquid Dampers

2012 ◽  
Vol 2012 ◽  
pp. 1-21 ◽  
Author(s):  
Hong-Nan Li ◽  
Ting-Hua Yi ◽  
Qin-Yang Jing ◽  
Lin-Sheng Huo ◽  
Guo-Xin Wang
Keyword(s):  
International Trade ◽  
Vibration Control ◽  
Design Procedure ◽  
Element Model ◽  
Wind Loading ◽  
Three Dimension ◽  
Analysis And Design ◽  
Tuned Liquid Dampers ◽  
Liquid Dampers ◽  
Wind Induced Vibration

This paper focuses on the wind-induced vibration control of the Dalian international trade mansion (DITM) by using the tuned liquid dampers (TLDs). To avoid the intensive computationally demanding problem caused by tens of thousand of degrees of freedom (DOF) of the structure in the numerical analysis, the three-dimension finite element model of the DITM is first simplified to the equivalent series multi-DOF system. The wind loading is subsequently simulated by the Davenport model according to the structural environmental condition where the actual samples of wind speed are measured. Following that, the shallow- and deep-water wave theories are applied to model the liquid sloshing inside TLDs, the tank sizing, and required water depth, and numbers of TLDs are given according to the numerical results of different cases. Comparisons between uncontrolled and controlled displacement and acceleration responses of the DITM under wind forces show that the designed shallow tank has higher efficiency than the deep one, which can effectively reduce the structural response amplitudes and enhance the comfortableness of the mansion. The preliminary TLD design procedure presented in this paper could be applied as a reference to the analysis and design of the wind-induced vibration for high-rise buildings using the TLD.

scholarly journals Interfacial crack arrest in sandwich beams subjected to fatigue loading using a novel crack arresting device – Numerical modelling

2017 ◽  
Vol 21 (2) ◽  
pp. 422-438 ◽  
Author(s):  
G Martakos ◽  
JH Andreasen ◽  
C Berggreen ◽  
OT Thomsen
Keyword(s):  
Finite Element ◽  
Sandwich Beam ◽  
Interfacial Crack ◽  
Fatigue Loading ◽  
Element Model ◽  
Crack Arrest ◽  
Design Tool ◽  
Fe Model ◽  
Sandwich Beams ◽  
Element Analysis

A novel crack arresting device is implemented in foam-cored composite sandwich beams and tested using the Sandwich Tear Test (STT) configuration. A finite element model of the setup is developed, and the predictions are correlated with observations and results from a recently conducted experimental fatigue test study. Based on a linear elastic fracture mechanics approach, the developed FE model is utilised to simulate crack propagation and arrest in foam-cored sandwich beam specimens subjected to fatigue loading conditions. The effect of the crack arresters on the fatigue life is analysed, and the predictive results are subsequently compared with the observations from the previously conducted fatigue tests. The FE model predicts the energy release rate and the mode mixity based on the derived crack surface displacements, utilising algorithms for the prediction of accelerated fatigue crack growth as well as the strain field evolution in the vicinity of the crack tip on the surface of the sandwich specimens. It is further shown that the developed finite element analysis methodology can be used to gain a deeper insight onto the physics and behavioural characteristics of the novel peel stopper concept, as well as a design tool that can be used for the implementation of crack arresting devises in engineering applications of sandwich components and structures.

Identification of Free-Free Modes From Constrained Vibration Data for Flexible Multibody Models

1999 ◽  
Author(s):  
Tong Y. Yi ◽  
Parviz E. Nikravesh
Keyword(s):  
Finite Element ◽  
Boundary Conditions ◽  
Finite Element Model ◽  
Degrees Of Freedom ◽  
Multibody System ◽  
Element Model ◽  
Flexible Body ◽  
Fe Model ◽  
Modal Data ◽  
Vibration Data

Abstract This paper presents a method for identifying the free-free modes of a structure by utilizing the vibration data of the same structure with boundary conditions. In modal formulations for flexible body dynamics, modal data are primary known quantities that are obtained either experimentally or analytically. The vibration measurements may be obtained for a flexible body that is constrained differently than its boundary conditions in a multibody system. For a flexible body model in a multibody system, depending upon the formulation used, we may need a set of free-free modal data or a set of constrained modal data. If a finite element model of the flexible body is available, its vibration data can be obtained analytically under any desired boundary conditions. However, if a finite element model is not available, the vibration data may be determined experimentally. Since experimentally measured vibration data are obtained for a flexible body supported by some form of boundary conditions, we may need to determine its free-free vibration data. The aim of this study is to extract, based on experimentally obtained vibration data, the necessary free-free frequencies and the associated modes for flexible bodies to be used in multibody formulations. The available vibration data may be obtained for a structure supported either by springs or by fixed boundary conditions. Furthermore, the available modes may be either a complete set; i.e., as many modes as the number of degrees of freedom of the associated FE model is available, or it can be an incomplete set.

Extraction of Free-Free Modes from Constrained Vibration Data for Flexible Multibody Models

2001 ◽  
Vol 123 (3) ◽  
pp. 383-389 ◽  
Author(s):  
Tong Y. Yi, ◽  
Parviz E. Nikravesh
Keyword(s):  
Finite Element ◽  
Boundary Conditions ◽  
Finite Element Model ◽  
Degrees Of Freedom ◽  
Multibody System ◽  
Element Model ◽  
Flexible Body ◽  
Fe Model ◽  
Modal Data ◽  
Vibration Data

This paper presents a method for identifying the free-free modes of a structure by utilizing the vibration data of the same structure with boundary conditions. In modal formulations for flexible body dynamics, modal data are primary known quantities that are obtained either experimentally or analytically. The vibration measurements may be obtained for a flexible body that is constrained differently than its boundary conditions in a multibody system. For a flexible body model in a multibody system, depending upon the formulation used, we may need a set of free-free modal data or a set of constrained modal data. If a finite element model of the flexible body is available, its vibration data can be obtained analytically under any desired boundary conditions. However, if a finite element model is not available, the vibration data may be determined experimentally. Since experimentally measured vibration data are obtained for a flexible body supported by some form of boundary conditions, we may need to determine its free-free vibration data. The aim of this study is to extract, based on experimentally obtained vibration data, the necessary free-free frequencies and the associated modes for flexible bodies to be used in multibody formulations. The available vibration data may be obtained for a structure supported either by springs or by fixed boundary conditions. Furthermore, the available modes may be either a complete set, having as many modes as the number of degrees of freedom of the associated FE model, or an incomplete set.

scholarly journals Analysis of stiffened laminated composite plates by finite element based on higher-order displacement theory

2008 ◽  
Vol 30 (2) ◽  
pp. 112-121 ◽  
Author(s):  
Tran Ich Thinh ◽  
Tran Huu Quoc
Keyword(s):  
Finite Element ◽  
Degrees Of Freedom ◽  
Plate Theory ◽  
Laminated Composite ◽  
Composite Plates ◽  
Element Model ◽  
Higher Order ◽  
Plate Element ◽  
Laminated Composite Plates ◽  
Element Free

In this paper, authors use a finite element model based on higher-order displacement plate theory for analysis of stiffened laminated composite plates. Transverse shear deformation is included in the formulation making the model applicable for both moderately thick and thin composite plates. The plate element used is a nine-noded isoparametric one with nine degrees of freedom at each node. The stiffness of stiffener is reflected at all nine nodes of plate element in which it is placed. Accordingly, the stiffeners can be positioned anywhere within the place element. Free vibration and deflection of stiffened laminated composite plates are carried out, and results are compared with existing analytical and other solutions.

Simplified FEM Model of Paper Machine Roll for Multibody Rolling Contact Analyses

2001 ◽  
Author(s):  
Veli-Matti Järvenpää ◽  
Erno K. Keskinen
Keyword(s):  
Finite Element ◽  
Degrees Of Freedom ◽  
Equations Of Motion ◽  
Element Model ◽  
Rolling Contact ◽  
Fe Model ◽  
Test Model ◽  
Paper Machine ◽  
Element Analysis ◽  
Computational Costs

Abstract In this paper a finite element model of a rotating paper machine roll for nip unit rolling contact analyses is discussed. This work presented here is based on the earlier work of the authors presented in [1] and [2]. The major motivations for developing a tailored FE-model including the large spin rotation are firstly to include the complex vibration phenomena as the shell vibrations of the roll structure in the analyses and secondly to reduce the computational costs of the numerical simulations due to the large number of degrees of freedom. The approach used is the use of the modal analysis i.e. to express the dynamics of the roll in terms of the lowest eigenmodes. The equations of motion are at first written in the rotating coordinates and then in addition to this the equations are expressed by using the modal coordinates. Numerical tests executed show that this modeling technique reduces computational costs significantly. Furthermore, use of the (semidefinite) eigenmode basis maintains the vibration characteristics of the roll structure. For verification purposes a test model was constructed and these simulation results were compared to the standard geometrically non-linear finite element analysis.

Free-Free Vibration Extraction From Available Vibration Data

2000 ◽  
Author(s):  
Thomas T. Yi
Keyword(s):  
Finite Element ◽  
Free Vibration ◽  
Boundary Conditions ◽  
Finite Element Model ◽  
Degrees Of Freedom ◽  
Element Model ◽  
Fe Model ◽  
Modal Data ◽  
Vibration Data ◽  
Dynamic Formulation

Abstract This paper presents a procedure for identifying the free-free vibration data of a structure from the available vibration data of the same structure with boundary conditions. For a structure in a mechanical system, depending upon the dynamic formulation used, we may need a set of free-free modal data or a set of constrained modal data. If a finite element model of the structure is available, its vibration data can be obtained analytically under any desired boundary conditions. However, if a finite element model is not available, the vibration data may be determined experimentally. Since experimentally measured vibration data are obtained for a structure supported by some form of boundary conditions, we may need to determine its free-free vibration data. The aim of this study is to extract, based on experimentally obtained vibration data, the necessary free-free frequencies and the associated modes for structures to be used in dynamic formulations. The available vibration data may be obtained for a structure supported either by springs or by fixed boundary conditions. Furthermore, the available modes may be either a complete set; i.e., as many modes as the number of degrees of freedom of the associated FE model is available, or it can be an incomplete set.

Long-Term Structural Analysis of 3-D Ship Structures Using a New Stiffened Plate Element

2000 ◽  
Vol 123 (1) ◽  
pp. 29-37 ◽  
Author(s):  
Y. V. Satish Kumar ◽  
Madhujit Mukhopadhyay ◽  
Tanmay Sarkar
Keyword(s):  
Finite Element ◽  
Structural Analysis ◽  
Coastal Waters ◽  
Degrees Of Freedom ◽  
Element Model ◽  
Computational Effort ◽  
Plate Element ◽  
Stiffened Plate ◽  
Principal Stresses

The paper presents the development of a technique for long-term 3-D structural analysis of the complete ship using a new stiffened plate element. The 3-D analysis involves the 3-D finite element modeling of the vessel and evaluation of hydrodynamic pressures using the 3-D linear diffraction theory. The elegance of the present stiffened plate element is that it can accommodate any number of arbitrarily oriented stiffeners within the plate element. Thus, the formulation obviates the use of mesh lines strictly along the longitudinals and transverses of the ship, which minimizes the required number of degrees of freedom of the finite element model of the complete vessel and reduces the computational effort considerably. The long-term prediction for the worst hydrodynamic pressures in the lifetime of the ship is carried out using the ISSC spectrum and scatter tables of Indian coastal waters. As an example problem, long-term structural analysis of a mini-bulk carrier in Indian coastal waters is presented in the paper. The long-term pressures are estimated with a probability of exceedence of 10−4 and principal stresses are calculated. It is shown that the present method provides a new, elegant, and economic technique for long-term 3-D structural analysis of the complete ship.

Harmonic Response of a Layered Halfspace Using Reduced Finite Element Model With Perfectly-Matched Layer Boundaries

2016 ◽  
Author(s):  
Simon Jones
Keyword(s):  
Finite Element ◽  
Degrees Of Freedom ◽  
Incident Angle ◽  
Element Model ◽  
Mode Shapes ◽  
Surface Load ◽  
Fe Model ◽  
Perfectly Matched Layers ◽  
Frequency Independent ◽  
Spatial Coordinates

The current paper investigates the use of perfectly-matched layers (PML) as absorbing elements for a finite element (FE) model simulating a semi-infinite medium. This formulation is convenient for application of Craig-Bampton reduction (CBR), which significantly reduce the number active degrees-of-freedom in the model in an attempt to improve the computational efficiency. The results from this investigation suggest the PML elements worked seamlessly with the FE elements to approximate the elastodynamic response of a 2D layered halfspace subjected to a surface load; the wave energy appears to be fully absorbed by the PMLs regardless of incident angle or wavelength. The size of the model is reduced by approximately 77% using the CBR, which transforms the system into a mixed set of coordinates, including both modal and spatial coordinates. The model reduction is accomplished by neglecting modal frequencies for the system above one and a half times the maximum forcing frequency of interest. By only transforming the frequency-independent FE section into modal coordinates, and leaving the frequency-dependent PML elements as spatial degrees-of-freedom, the mode-shapes must only be solved once and can then be reused for different forcing frequencies. The results from this investigation suggest this could provide computational benefits if a number of cases are being computed for different frequencies.

Finite Element Analysis of the Distributed Vibration Absorbers for Structural Noise Control

2005 ◽  
Author(s):  
Ashwini Gautam ◽  
Chris Fuller ◽  
James Carneal
Keyword(s):  
Finite Element ◽  
Numerical Model ◽  
Base Plate ◽  
Element Model ◽  
Fe Model ◽  
Vibration Absorbers ◽  
Element Analysis ◽  
Poroelastic Media ◽  
Hexahedral Elements ◽  
Component Models

This work presents an extensive analysis of the properties of distributed vibration absorbers (DVAs) and their effectiveness in controlling the sound radiation from the base structure. The DVA acts as a distributed mass absorber consisting of a thin metal sheet covering a layer of acoustic foam (porous media) that behaves like a distributed spring-mass-damper system. To assess the effectiveness of these DVAs in controlling the vibration of the base structures (plate) a detailed finite elements model has been developed for the DVA and base plate structure. The foam was modeled as a poroelastic media using 8 node hexahedral elements. The structural (plate) domain was modeled using 16 degree of freedom plate elements. Each of the finite element models have been validated by comparing the numerical results with the available analytical and experimental results. These component models were combined to model the DVA. Preliminary experiments conducted on the DVAs have shown an excellent agreement between the results obtained from the numerical model of the DVA and from the experiments. The component models and the DVA model were then combined into a larger FE model comprised of a base plate with the DVA treatment on its surface. The results from the simulation of this numerical model have shown that there has been a significant reduction in the vibration levels of the base plate due to DVA treatment on it. It has been shown from this work that the inclusion of the DVAs on the base plate reduces their vibration response and therefore the radiated noise. Moreover, the detailed development of the finite element model for the foam has provided us with the capability to analyze the physics behind the behavior of the distributed vibration absorbers (DVAs) and to develop more optimized designs for the same.

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