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2022 Vol. 43, No. 6
Published: 2022-12-28
669
Research progress on the preparation, characterization, and application of magnetoactive films
DOI: 10.19636/j.cnki.cjsm42-1250/o3.2022.029
Magnetoactive films are a kind of novel smart materials, whose mechanical, electrical, magnetic, and acoustic properties can be controlled by an external magnetic field. Thus, Magnetoactive films show wide application prospects in several fields. This paper focuses on the preparation, properties characterization, and application of magnetoactive films. First, this paper summarizes the preparation methods of magnetoactive films from the aspects of material design, preparation process, and structural design. The results show that the saturation magnetization of magnetoactive films is closely related to the types and content of doped magnetic particles. The elastic modulus of the matrix is the main factor that affects the elastic modulus of magnetoactive films. Then, the mechanical, electromagnetic, and acoustic performance characterization are systematically elaborated. Magnetoactive films exhibit excellent deformation properties when suffering from magnetic field. Meanwhile, magnetoactive films show outstanding magnetic and electric performances. The stiffness of magnetoactive films can be controlled by the external magnetic field, magnetoactive films show excellent acoustic properties. Finally, this paper enumerates the applications of magnetoactive films in the fields of sensors, actuators, flexible robots, etc. Due to the excellent softness, stretchability, and magnetic field controllable property, magnetoactive films can be used as sensing devices for magnetic field, force, and deformation detection. Moreover, magnetoactive films may be an ideal material for actuators due to the morphological changeability under the external magnetic field. Furthermore, magnetoactive films show great potential in soft robots, such as moving soft robots, grippers, medical soft robots, etc. In addition, high-performance acoustic, adsorption, and biomedical devices can be developed by making full use of the deformation properties of magnetoactive films. In summary, the development, problems, and challenges of magnetoactive films have been prospected. The external magnetic field can control the shape and characteristics of magnetoactive films, and then resulted in a broad application of magnetoactive films in acoustics, electromagnetics, biomedicine, etc. Although many studies have been carried out, there are still some problems to be solved in the further. The fabrication of ultra-thin or large size or high mechanical properties of magnetoactive film remains a problem. The mechanical properties of magnetoactive films under a high strain rate need further study. More research should be done to achieve practical application of magnetoactive films.
2022 Vol. 43 (6): 669-691 [
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692
Hermite Gradient Reproducing Kernel Collocation Method and Its Application in Static Analysis of Functionally Gradient Material Plates
DOI: 10.19636/j.cnki.cjsm42-1250/o3.2022.023
Since the direct collocation method has low solution accuracy on the boundary when solving boundary value problems, this paper proposes a Hermite Gradient Reproducing Kernel Collocation Method (HGCM) to improve the boundary solution accuracy. Reproducing kernel approximation is a commonly used approximation function in meshfree methods, but calculation of the high gradients is complex and time-consuming. HGCM adopts the gradient reproducing kernel functions to create any high-order derivatives of the approximation function. This improves the computational efficiency. The discrete equation is constructed by the Hermite collocation method, which improves the boundary solution accuracy. This method has high accuracy and high computational efficiency in solving the static problems of functionally graded material plates which is governed by a fourth-order partial differential equation of variant coefficients. The proposed method can be further applied to boundary value problems described by high-order partial differential equations.
2022 Vol. 43 (6): 692-702 [
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139
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703
Chemical Corrosion-Confining Pressure Meso-Damage Constitutive Model and Discrete Element Simulation of Rock
DOI: 10.19636/j.cnki.cjsm42-1250/o3.2022.024
Based on Lemaitre's theory of strain equivalence hypothesis, and the influence of chemical corrosion and confining pressure coupling on rock mechanical parameters is considered. Through nuclear magnetic resonance technology and damage mechanics theory, The meso-chemical damage variables and force damage variables are introduced, and the micro-element damage conforms to the SMP criterion, the evolution equation and constitutive model of the rock chemical corrosion-mechanics coupling damage are established, and the required model parameters are obtained by the method of theoretical derivation. Based on the particle discrete element method, the parameter radius multiplier was introduced to change the size of the bonding contact between particles, so as to simulate the hydrochemical damage. The flat joint model was used to simulate the triaxial compression of the rock after hydrochemical action, and the triaxial simulation curves of the rock under hydrochemical action and different confining pressures were obtained. By comparing the theoretical curve, discrete element simulation curve and test curve of the constructed rock chemical corrosion-mechanical coupling damage constitutive model,the results show that the three curves are in good agreement and the generation and distribution of cracks in rock during triaxial compression are obtained by discrete element method.
2022 Vol. 43 (6): 703-715 [
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130
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Experimental study on effect of injection pressure on fracture initiation and propagation in effective stress reforming
DOI: 10.19636/j.cnki.cjsm42-1250/o3.2022.025
2022 Vol. 43 (6): 716-726 [
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101
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727
Numerical simulation of thermal mechanical coupling behavior at crack tip of NiTi shape memory alloy
DOI: 10.19636/j.cnki.cjsm42-1250/o3.2022.026
In this paper, the thermomechanical coupling behavior at the mode I crack tip of NiTi shape memory alloy is numerically simulated and verified by experiments. A constitutive model including phase transformation and thermal mechanical coupling is established. The longitudinal strain, martensite volume fraction and temperature field near the crack tip are obtained by finite element calculation. The effective stress intensity factor at the crack tip was modified according to the martensitic transformation, and the effect of loading rate on the effective stress intensity shadow at the crack tip of shape memory alloy was revealed. Parametric study shows that with the increase of loading frequency, the temperature near the crack tip increases gradually, the martensitic transformation region decreases gradually, and the effective stress intensity factor decreases. The shape memory alloy shows toughening effect, which is helpful to slow down the crack growth. The results of this study have important reference significance for revealing the fatigue crack growth law of hyperelastic shape memory alloy under thermal mechanical coupling.
2022 Vol. 43 (6): 727-736 [
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128
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737
Heat conduction analysis of cracked orthotropic plates by using peri-dynamic differential operator
DOI: 10.19636/j.cnki.cjsm42-1250/o3.2022.027
A nonlocal model for heat conduction problems of orthotropic plates is developed by using peridynamic differential operator (PDDO). The boundary conditions and heat conduction equations are transformed from local differential form to nonlocal integral form by introducing the peridynamic function. Lagrange multipliers and variational analysis were introduced to solve the temperature and heat flux distributions at the crack tip of orthotropic plates. The convergence and effectiveness of the proposed model are verified by the comparative examples. The effects of orthotropy, material ply angle, crack angle and spacing on heat flux at crack tip were analyzed. The results show that the heat conduction model of orthotropic plate based on PDDO can effectively improve the calculation accuracy and predict the singularity of crack tip.
2022 Vol. 43 (6): 737-749 [
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175
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750
Eshelby Tensors for Three-dimensional Cubic Quasicrystal Materials with Ellipsoidal Inclusions
DOI: 10.19636/j.cnki.cjsm42-1250/o3.2022.028
The Quasicrystal (QC) particle-mixed composite (QCPMC) is a new class of composite which combines the excellent comprehensive properties of QCs giving rise to many promising technological applications. However, due to its unique microstructure, QCs possess phonon field, phase field, and phonon-phase coupling field, which is different from traditional solid materials. In order to optimize the QCPMCs effectively, the Eshelby tensor of the 3D cubic QCs material with ellipsoid inclusion is obtained by using Green’s function and Cauchy’s residue theorem, which is further used to explore the physical phenomenon of the influence of the quasicrystal particles distribution in mesoscopic scale on the macroscopic properties of QCPMC. The obtained Eshelby tensors are validated by degrading QCs to isotropic materials. Furthermore, the closed-form expressions are given when the particle shape are spheroid, elliptic cylinder, rod-shaped, penny-shaped, and ribbon-like, respectively. These expressions are the function of the particle shape and material properties. Moreover, it is found that the number of the independent non-zero components of the Eshelby tensor is 48, 17, 12 and 6, when the particle shape is spheroid, elliptic cylinder, sphere and penny-shaped, respectively. Finally, numerical studies are given to investigate the effect of particle aspect ratio. With the increasing of the aspect ratio, the increase of S3333 and S6363 is much larger than others, that is, Eshelby tensors related to x3 are more sensitive with respect to the particle shape. It is worth noting that the variation of the Eshelby tensors trend to flat when the aspect ratio approaches 10, and the convergence value of each tensor is close to the fixed value when ρ→∞, respectively. Consequently, when the aspect ration is larger than 10, the effect of the particle shape to the macroscopic properties of QCPMC is limited. For further applications, the solutions obtained in this paper can serve as the theoretical basis to obtain the effective properties of QCPMC, and solve the more complicated problems, such as fracture problem and defect behavior of QCs.
2022 Vol. 43 (6): 750-762 [
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177
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763
Study on Flutter Characteristics and Vibration Suppression of a Composite Laminated Plate
DOI: 10.19636/j.cnki.cjsm42-1250/o3.2022.033
The flutter characteristics and the vibration suppression of a composite laminate in the supersonic flow are studied. The first-order piston theory is used to calculate the aerodynamic pressure in the supersonic flow field. The dynamic model of a piezoelectric composite laminate is deduced by using the classical laminate theory and the Hamilton's principle. The sliding observer is designed to reduce the observation overflow, and the Lyapunov method is used to prove the stability. The LQR controller is designed based on the observed state. The effects of geometric parameters and fiber angles on the flutter characteristics of piezoelectric composite laminates are studied. The impulse response of the laminated plate is solved by SIMULINK simulation to verify the effectiveness of the controller. The results show that reasonable planning of the geometric parameters and fiber angle of the laminated plate can improve the system flutter stability. The sliding mode observer can trace the original system more accurately and has good robustness. The LQR control can eliminate the flutter point of the laminate within a certain range, and also can effectively suppress the vibration of the piezoelectric composite laminate at the flutter boundary, with the increase of the Q matrix, and the vibration suppression effect is better. The LQR control effect is better with the thickness of the piezoelectric layer becomes larger.
2022 Vol. 43 (6): 763-772 [
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84
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773
The Elastic Property Variations of Nb3Sn During Superconducting Transition
DOI: 10.19636/j.cnki.cjsm42-1250/o3.2022.035
Quench of a Nb3Sn superconductor is an important phenomenon in the operation of superconducting magnet equipment. It is a transient process that the superconductor transforms from superconducting phase to normal phase. In the Nb3Sn material’s application in the construction of the high-field-superconducting-magnet, the quench is accompanied by the instantaneous drastic change of the mechanical, thermal and electrical parameters because of the high energy storage density. During a quench, the superconducting phase transition is accompanied by the abrupt change of elastic properties of Nb3Sn. The study of this change is the key to the microscopic and multiscale modelling of the stress arising from the superconducting-normal transition. In this paper, the first-principle calculation method is used to calculate the variation of the elastic constants with temperature, and the results show that due to the lack of the consideration of the effect of the variations of the special electronic band structure of Nb3Sn with the ambient temperature, the elastic constants of Nb3Sn, extrapolated from 0K to the finite temperature based on the quasi-static approximation method, show qualitative difference between the calculations and the experimental observations. Then, based on the function of lattice free energy, an analytical model is given to describe the variation of the elastic properties of cubic Nb3Sn single crystal with temperature. The model predictions are qualitatively consistent with the experimental results, and an analytical description of the elastic properties of Nb3Sn single crystal during the superconducting phase transition is given. The results of the study will contribute to the development of the modelling and numerical simulation of the stress generating by the quench, and lay a foundation of the safety analysis of the superconducting magnets.
2022 Vol. 43 (6): 773-782 [
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783
Study on rigidity strengthening of aircraft slotted large opening structure
DOI: 10.19636/j.cnki.cjsm42-1250/o3.2022.037
in order to meet the aircraft stiffness requirments of the typical rectagular fuselage with large opening, a design scheme of adding four side beams to the groove large opening structure to strengthen the stiffness was designed and its engineering analysis model is constructed. The bending stiffness and torsional stiffness are compared with the typical rectagular fuselage without openings.The stiffness ratio of the two kinds of configuration are obtained, and then the formula for sectional area of side beams are given under a certain stiffness index. Besides, the curves of stiffness ratio with area of side beams and the stiffness strengthen process for rectangular fuselage with large opening are also shown. This study can be used in the scheme phase of the large opening structure plane strengthen design.
2022 Vol. 43 (6): 783-790 [
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108
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