Magnetic poles enabled kirigami meta-structure for stable mechanical memory storage with high information density

Some bi or multi-stable Mechanical meta-structures have been implemented as mechanical memory devices which however are with limits such as complex structural forms, low information storage capability and/or fragile structural stability to maintain the stored information bits robustly under external interferences. To address these issues, we refer to the structural intelligence by constructing a simple 3D-printable multi-layered cylindrical kirigami module with gradient structural parameters and propose a mechanical memory device that can robustly store information bits exponentially larger than previous designs. We demonstrate the promising enhancement of information storage capability of our proposed mechanical memory device relies on two mechanisms 1 the deformation sequences of the kirigami module enabled by the gradient structural parameter, which brings the extra dimensional degree of freedom to break the traditional mechanical memory unit with only planar form and merits information bits with spatially combinatorical programmability, and 2 the combinatorics of the deformation independences among the cylindrical kiriagmi unit arrays in the constructed mechanical memory device. Particularly, we achieve both the structural stabilities and the desired structural robustness in the mechanical memory devices by additively introducing magnetic N-S poles in units, which can protect the stored information from interferences like mechanical crushing, impacting and or shaking

The Study of Thermal Stresses of a Two Phase FGM Hollow Sphere

This article focuses on the analytical solution for uniform heating of a FGM hollow sphere made of two phase of different materials. It is assumed that the volume fraction of one phase is a function f1=(rn-an)/(bn-an) varied in the radial direction. Based on the Voigt constant strain approximation, analytical solutions of stresses, displacements and the effective coefficient of thermal expansion are obtained. The effects of the volume fraction, Poisson’s ratio, Young’s moduli and coefficients of thermal expansion on the solutions are studied. Two special cases, constant elastic modulus and constant coefficient of thermal expansion, are finally discussed

A Theoretical Analysis on Elastic and Elastoplastic Stress Solutions for Functionally Graded Materials Using Averaging Technique of Composites

Functionally Graded Materials (FGMs) are being used in an everexpanding set of applications. For better applications, an analytical methodology using averaging technique of composites is developed to describe the thermo-elastic and thermo-elastoplastic behaviors of a three-layered FGM system subjected to thermal loading Solutions using averaging technique of composites for the stress distributions in a generic FGM system subjected to arbitrary temperature loading conditions are presented. The power-law strain hardening behaviour is assumed for the FGM metallic phase and the stress of the metallic phase are calculated to judge the plastic in this work The stress distributions within the FGM systems are compared with accurate numerical solutions obtained from finite element analyses and good agreement is found

An interference-reducing precoding for SCMA multicast design based on complementary sequences

In a multi-group multicast sparse code multiple access (SCMA) system, one base station multicasts common messages to multiple multicast groups via different code books. To accommodate more user terminals (UTs), traditional multicast systems have multiple transmitters, each of which works in one-to-many mode. In this way, each UT is subject to inter-transmitter interference. Considering the high degrees of freedom for transmitting and receiving, it is difficult to separate the desired signal from interference signals. Therefore, an interference-reducing precoding scheme is required to ensure the reliability of SCMA multicast communication system. For the SCMA multicast system design, we present three necessary conditions that the interference-reducing matrix should satisfy. Then, the precoding matrix satisfying the three necessary conditions simultaneously is designed by utilizing the complementary sequences (CS) and complete complementary sequences (CCS). In this context, we consider two scenarios with different transmission modes (single-cell and multiple-cell) and different precoding schemes (based on CS and CCS). Simulation results show that proposed transmission schemes can significantly reduce the bit error rate of multicast groups while ensuring the communication throughput, and behave a superior performance over other alternatives. Moreover, theoretical and simulation results also prove that the proposed precoding vectors have perfect average power radiation and omnidirectional coverage performance

Revisiting the electroelastic solution for an FGPM thick-walled cylinder subjected to mechanical and electric loadings

Abstract Theoretical analysis for an empty thick-walled FGPM cylinder exposed to electric and mechanical loadings are investigated. The cylinder is a composite material composed of PZT4 and PVDF and the volume fraction of PZT4 is given by the power law with three controllable parameters which can cover more complex circumstances. The hypergeometric equation of the radial displacement is acquired by utilizing the Voigt method, and the solutions of the stresses and the electric potential are obtained after solving the radial displacement. The method in this paper is appropriate for real functionally graded piezoelectric materials and can avoid assumptions about unknown overall material parameters appeared in previous references. Finally, the impacts of the parameter n in volume fraction of FGPM cylinder on mechanical and electric behaviors are examined. Furthermore, the distinction between the hoop stress and radial stress is discussed to decrease the pressure concentration in FGPM cylinder.</jats:p

An Approximate Thermoelastic Theoretical Solution of Functional Graded Thick-Walled Tube Based on the Mori-Tanaka Method

Purposes There is a problem of not considering the microstructure influence of component materials when analyzing the thermoelastic problem of functionally graded thick-walled tubes at present. Evaluating the equivalent parameters of functionally graded materials based on micromechanics methods such as the Mori-Tanaka method can effectively solve the problem mentioned above. However, existing literatures only provide numerical solutions based on the Mori-Tanaka method for functionally graded thick-walled tubes under combined thermal and mechanical loads. And in their works, only the spherical inclusion is considered. Methods To address the aforementioned issues, the thermoelastic problem of functionally graded thick-walled tubes is analyzed on the basis of the Mori-Tanaka method, and provides an approximate thermoelastic theoretical solution is provided. This theoretical solution not only has a high degree of compatibility with the numerical solution, but also considers the influence of inclusion shape on its physical quantities. Finally, the effects of inclusion shape on radial displacement and stresses under different boundary conditions are analyzed. Finding The results show that under both boundary conditions, the shape of the inclusion has a significant impact on the radial displacement. However, under the temperature boundary condition, the shape of inclusion has a significant impact on radial stress, but has a relatively small impact on axial and circumferential stresses. Under the stress boundary condition, the shape of inclusion has a greater impact on axial stress, but a smaller impact on circumferential and radial stresses