Thermo-mechanical analysis of multilayered composite beams based on a new mixed global-local model

2019 ◽  
Vol 53 (28-30) ◽  
pp. 3963-3978 ◽  
Author(s):  
Qilin Jin ◽  
Ziming Mao ◽  
Xiaofei Hu ◽  
Weian Yao
Keyword(s):  
Transverse Shear ◽  
Order Theory ◽  
Mechanical Analysis ◽  
Composite Beams ◽  
Higher Order ◽  
Shear Stresses ◽  
Mixed Form ◽  
Multilayered Composite ◽  
Proposed Model ◽  
Higher Order Theory

An accurate mixed-form global-local higher-order theory including transverse normal thermal deformation is developed for thermo-mechanical analysis of multilayered composite beams. Although transverse normal deformation is considered, the number of displacement parameters is not increased. The proposed mixed-form global-local higher-order theory is derived using the displacement assumptions of global-local higher-order theory in conjunction with the Reissner mixed variational theorem. Moreover, the mixed-form global-local higher-order theory retains a fixed number of displacement variables regardless of the number of layers. In order to obtain the improved transverse shear stresses, the three-dimensional equilibrium equation is used. It is significant that the second-order derivatives of in-plane displacement variables have been eliminated from the transverse shear stress field, such that the finite element implementation is greatly simplified. The benefit of the proposed mixed-form global-local higher-order theory is that no post-processing integration procedure is needed to accurately calculate the transverse shear stresses. The equilibrium equations and analytical solution of the proposed model can be obtained based on the Reissner mixed variational equation. The performance of the proposed model is assessed through different numerical examples, and the results show that the proposed model can better predict the thermo-mechanical responses of multilayered composite beams.

scholarly journals Understandable robots - What, Why, and How

2018 ◽  
Vol 9 (1) ◽  
pp. 110-123 ◽  
Author(s):  
Thomas Hellström ◽  
Suna Bensch
Keyword(s):  
Theory Of Mind ◽  
Order Theory ◽  
Higher Order ◽  
Proposed Model ◽  
Higher Order Theory ◽  
Communicative Actions ◽  
The Mind ◽  
Novel Model

Abstract As robots become more and more capable and autonomous, there is an increasing need for humans to understand what the robots do and think. In this paper, we investigate what such understanding means and includes, and how robots can be designed to support understanding. After an in-depth survey of related earlier work, we discuss examples showing that understanding includes not only the intentions of the robot, but also desires, knowledge, beliefs, emotions, perceptions, capabilities, and limitations of the robot. The term understanding is formally defined, and the term communicative actions is defined to denote the various ways in which a robot may support a human’s understanding of the robot. A novel model of interaction for understanding is presented. The model describes how both human and robot may utilize a first or higher-order theory of mind to understand each other and perform communicative actions in order to support the other’s understanding. It also describes simpler cases in which the robot performs static communicative actions in order to support the human’s understanding of the robot. In general, communicative actions performed by the robot aim at reducing the mismatch between the mind of the robot, and the robot’s inferred model of the human’s model of the mind of the robot. Based on the proposed model, a set of questions are formulated, to serve as support when developing and implementing the model in real interacting robots.

Interlaminar stress analysis of multilayered composites based on the Hu-Washizu variational theorem

2017 ◽  
Vol 52 (13) ◽  
pp. 1765-1779 ◽  
Author(s):  
Wu Zhen ◽  
Chen Wanji
Keyword(s):  
Transverse Shear ◽  
Equilibrium Equation ◽  
Beam Element ◽  
Composite Beams ◽  
Higher Order ◽  
Shear Stresses ◽  
Interlaminar Stresses ◽  
Beam Elements ◽  
Transverse Shear Stresses ◽  
Derivatives Of

Up to date, accurate prediction of interlaminar stresses is still a challenging issue for two-node beam elements. The postprocessing approaches by integrating the three-dimensional equilibrium equation have to be used to obtain improved transverse shear stresses, whereas the equilibrium approach requires the first-order derivatives of in-plane stresses. In-plane stresses within two-node beam element are constant, so the first-derivatives of in-plane stresses are close to zero. Thus, two-node beam elements encounter difficulties for accurate prediction of transverse shear stresses by the constitutive equation or the equilibrium equation, so a robust two-node beam element is expected. A two-node beam element in terms of the global higher-order zig-zag model is firstly developed by employing the three-field Hu-Washizu mixed variational principle. By studying the effects of different boundary conditions, stacking sequence and loading on interlaminar stresses of multilayered composite beams, it is shown that the proposed two-node beam element yields more accurate results with lesser computational cost compared to various higher-order models. It is more important that accurate transverse shear stress has active impact on displacements and in-plane stresses of multilayered composite beams.

scholarly journals Vibration of Antisymmetric Angle-Ply Laminated Plates of Higher-Order Theory with Variable Thickness

2018 ◽  
Vol 2018 ◽  
pp. 1-14 ◽  
Author(s):  
A. K. Nor Hafizah ◽  
J. H. Lee ◽  
Z. A. Aziz ◽  
K. K. Viswanathan
Keyword(s):  
Free Vibration ◽  
Variable Thickness ◽  
Plate Theory ◽  
Order Theory ◽  
Higher Order ◽  
Laminated Plates ◽  
Shear Stresses ◽  
Transverse Shear Stresses ◽  
Thickness Variations ◽  
Higher Order Theory

Free vibration of antisymmetric angle-ply laminated plates with variable thickness is studied. Higher-order shear deformation plate theory (HSDT) is introduced in the present method to remove the shear correction factors and improve the accuracy of transverse shear stresses. The thickness variations are assumed to be linear, exponential, and sinusoidal. The coupled differential equations are obtained in terms of displacement and rotational functions and approximated using cubic and quantic spline. A generalized eigenvalue problem is obtained and solved numerically by employing the eigensolution techniques with eigenvectors as spline coefficients to obtain the required frequencies. The results of numerical calculations are presented for laminated plates with simply supported boundary conditions. Comparisons of the current solutions and those reported in literature are provided to verify the accuracy of the proposed method. The effects of aspect ratio, number of layers, ply-angles, side-to-thickness ratio, and materials on the free vibration of cylindrical plates are discussed in detail.

A Higher-Order Theory for Plane Stress Conditions of Laminates Consisting of Isotropic Layers

1999 ◽  
Vol 66 (1) ◽  
pp. 95-100 ◽  
Author(s):  
X. J. Wu ◽  
S. M. Cheng
Keyword(s):  
Three Dimensional ◽  
Order Theory ◽  
Higher Order ◽  
Shear Stresses ◽  
Stress Equilibrium ◽  
Material Discontinuities ◽  
Interlaminar Shear ◽  
Higher Order Theory ◽  
Three Dimensional Elasticity ◽  
Higher Order Functions

In this paper, a higher-order theory is derived for laminates consisting of isotropic layers, on the basis of three-dimensional elasticity with displacements as higher-order functions of z in the thickness direction. The theory employs three stress potentials, Ψ (an Airy function), p (a harmonic function), and its conjugate q, to satisfy all conditions of stress equilibrium and compatibility. Interlaminar shear stresses, i.e., antiplane stresses, are shown to be present at the interfaces, especially near material discontinuities where gradients of in-plane stresses are usually high. For illustrating its practical application, the problem of a plate containing a hole patched with an intact plate is solved.

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