On an isoparametric finite-element for composite laminates with finite rotations

1993 ◽  
Vol 12 (6) ◽  
pp. 329-348 ◽  
Author(s):  
Y. Basar ◽  
U. Montag ◽  
Y. Ding
Keyword(s):  
Finite Element ◽  
Composite Laminates ◽  
Finite Rotations ◽  
Isoparametric Finite Element

scholarly journals Free Edge Strain Concentrations in Real Composite Laminates: Experimental-Theoretical Correlation

1985 ◽  
Vol 52 (4) ◽  
pp. 787-793 ◽  
Author(s):  
C. T. Herakovich ◽  
D. Post ◽  
M. B. Buczek ◽  
R. Czarnek
Keyword(s):  
Finite Element ◽  
Shear Strain ◽  
Composite Laminates ◽  
Critical Angle ◽  
Axial Strain ◽  
Free Edge ◽  
Experimental Results ◽  
Resin Matrix ◽  
Maximum Shear Strain ◽  
Isoparametric Finite Element

The magnitude of the maximum shear strain at the free edge of axially loaded [θ2/–θ2]s and [(± θ)2]s composite laminates was investigated experimentally and numerically to ascertain the actual value of strain concentration in resin matrix laminates and to determine the accuracy of finite element results. Experimental results using moire´ interferometry show large, but finite, shear strain concentrations at the free edge of graphite-epoxy and graphite-polyimide laminates. Comparison of the experimental results with those obtained using several different finite element representations showed that a four-node isoparametric finite element provided the best and most trouble-free numerical results. The results indicate that the ratio of maximum shear strain at the free edge to applied axial strain varies with fiber orientation and does not exceed nine for the most critical angle which is 15 deg.

Modal Analysis of the Axial Compressor Blade: Advanced Time-Dependent Electronic Interferometry and Finite Element Method

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Mykhaylo Tkach ◽  
Serhii Morhun ◽  
Yuri Zolotoy ◽  
Irina Zhuk
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Finite Element ◽  
High Reliability ◽  
Axial Compressor ◽  
Time Dependent ◽  
Experimental Setup ◽  
Vibration Modes ◽  
Compressor Blades ◽  
Isoparametric Finite Element

AbstractNatural frequencies and vibration modes of axial compressor blades are investigated. A refined mathematical model based on the usage of an eight-nodal curvilinear isoparametric finite element was applied. The verification of the model is carried out by finding the frequencies and vibration modes of a smooth cylindrical shell and comparing them with experimental data. A high-precision experimental setup based on an advanced method of time-dependent electronic interferometry was developed for this aim. Thus, the objective of the study is to verify the adequacy of the refined mathematical model by means of the advanced time-dependent electronic interferometry experimental method. The divergence of the results of frequency measurements between numerical calculations and experimental data does not exceed 5 % that indicates the adequacy and high reliability of the developed mathematical model. The developed mathematical model and experimental setup can be used later in the study of blades with more complex geometric and strength characteristics or in cases when the real boundary conditions or mechanical characteristics of material are uncertain.

2-D electromagnetic modeling by finite‐element method with a dipole source and topography

Geophysics ◽  
2000 ◽  
Vol 65 (2) ◽  
pp. 465-475 ◽  
Author(s):  
Yuji Mitsuhata
Keyword(s):  
Finite Element ◽  
Delta Function ◽  
Dipole Source ◽  
Electromagnetic Modeling ◽  
Secondary Field ◽  
Controlled Source ◽  
Transient Electromagnetic ◽  
Isoparametric Finite Element ◽  
Anomalous Bodies ◽  
Element Technique

I present a method for calculating frequency‐domain electromagnetic responses caused by a dipole source over a 2-D structure. In modeling controlled‐source electromagnetic data, it is usual to separate the electromagnetic field into a primary (background) and a secondary (scattered) field to avoid a source singularity, and only the secondary field caused by anomalous bodies is computed numerically. However, this conventional scheme is not effective for complex structures lacking a simple background structure. The present modeling method uses a pseudo‐delta function to distribute the dipole source current, and does not need the separation of the primary and the secondary field. In addition, the method employs an isoparametric finite‐element technique to represent realistic topography. Numerical experiments are used to validate the code. Finally, a simulation of a source overprint effect and the response of topography for the long‐offset transient electromagnetic and the controlled‐source magnetotelluric measurements is presented.

scholarly journals An Improved Analytical Solution for Process-Induced Residual Stresses and Deformations in Flat Composite Laminates Considering Thermo-Viscoelastic Effects

Materials ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 2506 ◽  
Author(s):  
Chao Liu ◽  
Yaoyao Shi
Keyword(s):  
Differential Equation ◽  
Finite Element ◽  
Analytical Solution ◽  
Residual Stresses ◽  
Composite Laminates ◽  
Composite Structures ◽  
Numerical Models ◽  
Element Analysis ◽  
Current Time ◽  
Viscoelastic Effects

Dimensional control can be a major concern in the processing of composite structures. Compared to numerical models based on finite element methods, the analytical method can provide a faster prediction of process-induced residual stresses and deformations with a certain level of accuracy. It can explain the underlying mechanisms. In this paper, an improved analytical solution is proposed to consider thermo-viscoelastic effects on residual stresses and deformations of flat composite laminates during curing. First, an incremental differential equation is derived to describe the viscoelastic behavior of composite materials during curing. Afterward, the analytical solution is developed to solve the differential equation by assuming the solution at the current time, which is a linear combination of the corresponding Laplace equation solutions of all time. Moreover, the analytical solution is extended to investigate cure behavior of multilayer composite laminates during manufacturing. Good agreement between the analytical solution results and the experimental and finite element analysis (FEA) results validates the accuracy and effectiveness of the proposed method. Furthermore, the mechanism generating residual stresses and deformations for unsymmetrical composite laminates is investigated based on the proposed analytical solution.

Modeling of smart composite laminates including debonding - A finite element approach

1997 ◽  
Author(s):  
Charles Seeley ◽  
Aditi Chattopadhyay ◽  
Charles Seeley ◽  
Aditi Chattopadhyay
Keyword(s):  
Finite Element ◽  
Composite Laminates ◽  
Smart Composite ◽  
Finite Element Approach ◽  
Element Approach
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