Data Mining Practical Machine Learning Tools and Techniques

INTRODUCTION TO COMPOSITE MATERIALS Chapter Objectives Introduction Classi?cation Recycling Fiber-Reinforced Composites Mechanics Terminology Summary Key Terms Exercise Set References MACROMECHANICAL ANALYSIS OF A LAMINA Chapter Objectives Introduction Review of De?nitions Hooke's Law for Different Types of Materials Hooke's Law for a Two-Dimensional Unidirectional Lamina Hooke's Law for a Two-Dimensional Angle Lamina Engineering Constants of an Angle Lamina Invariant Form of Stiffness and Compliance Matrices for an Angle Lamina Strength Failure Theories of an Angle Lamina Hygrothermal Stresses and Strains in a Lamina Summary Key Terms Exercise Set References APPENDIX A: MATRIX ALGEBRA Key Terms APPENDIX B: TRANSFORMATION OF STRESSES AND STRAINS Transformation of Stress Transformation of Strains Key Terms MICROMECHANICAL ANALYSIS OF A LAMINA Chapter Objectives Introduction Volume and Mass Fractions, Density, and Void Content Evaluation of the Four Elastic Moduli Ultimate Strengths of a Unidirectional Lamina Coefficients of Thermal Expansion Coefficients of Moisture Expansion Summary Key Terms Exercise Set References MACROMECHANICAL ANALYSIS OF LAMINATES Chapter Objectives Introduction Laminate Code Stress-Strain Relations for a Laminate In-Plane and Flexural Modulus of a Laminate Hygrothermal Effects in a Laminate Summary Key Terms Exercise Set References FAILURE, ANALYSIS, AND DESIGN OF LAMINATES Chapter Objectives Introduction Special Cases of Laminates Failure Criterion for a Laminate Design of a Laminated Composite Other Mechanical Design Issues Summary Key Terms Exercise Set References BENDING OF BEAMS Chapter Objectives Introduction Symmetric Beams Nonsymmetric Beams Summary Key Terms Exercise Set References INDEX

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Mechanics of composite materials

3D meso-scale fracture modelling and validation of concrete based on in-situ X-ray Computed Tomography images using damage plasticity model

Generation of 3D representative volume elements for heterogeneous materials: a review

Independence-oriented VMD to identify fault feature for wheel set bearing fault diagnosis of high speed locomotive

https://robots.iopscience.iop.org/article/10.1088/1361-6463/ac026a/pdf

Efficient pure-mode elastic mode-converting diode

To realize extraordinary wave phenomena, metamaterials need to attain unique effective material properties. In this work, we propose an inverse design strategy for metamaterials with specific anisotropic EMD (effective mass density). Although the conventional inverse homogenization technique has been extended to various fields, few works have been published to explore the inverse realization of an EMD tensor, each component of which is supposed to gain a given value at a target frequency. To this end, we propose a calculation scheme, in which the EMD tensor can be calculated in a much similar way to the homogenized static stiffness. Therefore, the scheme is quite convenient for sensitivity analysis. The coating layer interfacing the core and matrix is chosen as the design region because it directly determines the motion of the core. The matrix layout, which not only contributes to the stiffness of the metamaterial but also highly affects the core's local motion, is chosen carefully. The perfect transmodal Fabry–Perot interference phenomenon is considered in this work, and through several numerical examples, the phenomenon is ideally realized. The proposed design strategy could be critically useful in designing locally resonant metamaterials with general anisotropy.

Inverse design of locally resonant metamaterial with anisotropic mass density for perfect transmodal Fabry–Pérot interference

Abstract. In recent years, quantum communication technology has gradually entered the practical stage. Multiple quantum key distribution (QKD) networks have been built and tested all over the world. However, quantum communication networking mode always evolves from a point-to-point network to a many-to-many network. The major challenges in quantum communication are secret key rate, distance, cost, and size of QKD devices. We proposed a low-cost, lightweight-client, twin-field QKD network with wavelength division multiplexing (WDM). The proposed implementation adopts polarization multiplexing, time-division multiplexing, and WDM technology to solve all these major challenges and implement a many-to-many dynamic communications network. Furthermore, our scheme can effectively reduce the cost to less than half of that of current QKD networks and has reference significance for large-scale deployment of QKD networks.

Low-cost lightweight-client twin-field quantum key distribution network with wavelength division multiplexing

The strength of rocks under complex stress can be regarded as a function of stress state. This function is generally referred to as a failure criterion. In the past century, a large number of criteria have been proposed for rock materials. Among these criteria, the Mohr–Coulomb criterion and Hoek–Brown criterion might be the most commonly used in rock engineering practice. A major limitation of these criteria is that the influence of the intermediate principal stress is not considered. There have been a number of attempts to develop modified failure criteria based on the Mohr–Coulomb criterion or the Hoek–Brown criterion to include the effect of intermediate principal stress for rocks (Priest 2005; Zhang 2008; Singh et al. 2011). The Drucker–Prager criterion is another widely used criterion as a smooth approximation to the Mohr–Coulomb criterion. It is worth noting that although the Drucker–Prager criterion includes the intermediate principal stress effect, it neglects the influence of stress angle (also called similarity angle) on the cross-sectional shape of the failure surface. This problem is often ignored in rock engineering practice when the Drucker–Prager criterion is applied, however, many experimental results indicate that it is important to take this problem seriously. It has been pointed out that the Drucker–Prager criterion with a circular cross section “gives a very poor approximation to the real failure conditions” (Humpheson and Naylor 1975; Zienkiewicz and Pande 1977). Chen (1982) argued that “the trace of the failure surface on a deviatoric plane is noncircular but depends on the angle of similarity ”. Ottosen and Ristinmaa (2005) recommended that “Due to the elimination of the cos 3 -term, the Drucker–Prager criterion should be used with caution”. Yu (2006) pointed out that “experimental research also suggests that its circular shape on a deviatoric plane does not agree well with experimental data, for this reason, care is needed when the Drucker–Prager plasticity model is used in geotechnical analysis”. Neto et al. (2008) summarized several cases of Drucker–Prager approximation to the Mohr–Coulomb criterion and noted “any of the above approximations to the Mohr–Coulomb criterion can give a poor description of the material behavior for certain states of stress”. Some studies provide a theoretical basis for solving the problem. Five requirements for describing the general properties of failure criteria are summarized by Yu (2018). They are as follows:

A Failure Criterion Considering Stress Angle Effect

An approach for the aerodynamic optimization design of elastic configuration is implemented and tested. Aeroelastic analysis was carried out by coupling Euler equations solver and finite-element structural solver. Two important techniques used in high-fidelity aerostructural design optimization are discussed, which are the grid deformation method and the update method of finite-element mesh (FEM). An improved grid deformation methodology based on transfinite interpolation (TFI) and radial basis function (RBF) method is presented, which adapts to complex configuration very well. The technique to update the FEM is based on bilinear interpolation method and RBF method, and it adapts to any grid type of finite-element model. Discrete adjoint method is used to get the gradient of objective function with respect to design variables. Optimizations of a wing and a more realistic wing-body configuration are done to demonstrate the effectiveness of the proposed approach. Results show that the lift to drag ratio can be improved with constraints through optimization, which indicates that the present methodology can be successfully applied to the optimization design of transonic jig shape of aircraft.

Yueming Li

Papers

Efficient pure-mode elastic mode-converting diode

Inverse design of locally resonant metamaterial with anisotropic mass density for perfect transmodal Fabry–Pérot interference

Low-cost lightweight-client twin-field quantum key distribution network with wavelength division multiplexing

A Failure Criterion Considering Stress Angle Effect

Efficient Multidisciplinary Aerodynamic Optimization Design Based on Discrete Adjoint Method