Acta Mechanica Solida Sinica最新文献

Inorganic perovskites, a class of materials with the general formula ABX₃, exhibit a wide range of electronic, dielectric, and structural properties, making them pivotal in energy, electronics, and catalysis applications. Accurate atomistic simulations of these materials require accurate interatomic potentials that capture both short-range and long-range interactions. While first-principles methods are of high accuracy, empirical and machine learning potentials remain essential for large-scale simulations. This survey categorizes and reviews the atomic potentials used in inorganic perovskite modeling based on how they treat electrostatic interactions: potentials without charges, potentials with constant charges, and potentials with variable charges. Given the ionic nature of perovskites, we emphasize the importance of charge treatment, and each class of potentials is discussed in detail with representative examples, functional forms, and application scenarios. For comparison, we perform molecular dynamics simulations to calculate the critical temperature for the phase transition of the perovskite CsPbI₃ with available empirical potentials, highlighting their strengths and limitations in capturing structural evolution. Finally, we outline future directions for developing more accurate and transferable atomic potentials for inorganic perovskites. We hope that this review can serve as a guiding resource for researchers who are starting to perform simulations for inorganic perovskites.

Acoustic metamaterials (AMs) exhibit outstanding sound absorption performance due to their customizable design. In this work, a low-frequency sound-absorbing metamaterial plate, which combines a fractal-based labyrinth acoustic metamaterial (FLAM) and a micro-perforation panel, is proposed. The theoretical, simulation, and experimental methods are used to comprehensively examine the sound absorption performance. A triangular fractal curve is first introduced, and the combined FLAM model is constructed. An equivalent straight channel model is developed to study the effects of the structural parameters on the sound absorption coefficients. The finite element analysis (FEA) is further conducted to validate the theoretical results. All the findings indicate that the proposed combined FLAM exhibits excellent sound absorption performance at a deep sub-wavelength scale, with absorption coefficients of 0.89, 0.98, and 1.00 for the first three fractal orders, respectively. Finally, the prototypes are fabricated, and the impedance tube experiments are conducted, yielding results that align closely with both analytical and FEA results. Notably, the sound absorption performance of large-area sound-absorbing plates is also investigated by splicing two/four FLAMs together, demonstrating a relative absorption bandwidth exceeding 35%. This work offers a viable alternative to low-frequency sound-absorbing materials for potential engineering applications.

Based on the linear elasticity theory of quasicrystals, this study addresses two defect problems in two-dimensional piezoelectric quasicrystals: rigid inclusions and holes. Using the Stroh formalism, Green’s function solutions are obtained for these defects under concentrated and uniformly distributed forces. Numerical examples are presented to analyze the mechanical behavior when loads are applied at various positions, including the center, outside, on the boundary, and at infinity of the elliptical defect. The study emphasizes the significant impact of the phonon line force on the distribution of key physical quantities. Results show that elliptical defects significantly disrupt multiple physical fields, leading to substantial variations in displacement and potential at the hole boundaries and pronounced stress concentrations. The stress in the phason field near the elliptical defect boundary exhibits complex variations under loading conditions, and the piezoelectric effect becomes more pronounced. These findings provide critical guidance for designing quasicrystal-based smart materials with controlled defect responses.

This paper proposes a state-of-the-art three-dimensional Voronoi cell finite element method (3D VCFEM) aimed at investigating the mechanical properties of particle-reinforced composites (PRCs) in space under different microstructural properties. Firstly, the modified residual energy generalized function of 3D VCFEM was proposed by applying the hybrid stress element method, and the element format of the 3D Voronoi element was constructed. On this basis, the interaction between the matrix and the inclusions was considered, and the higher-order stress function including the interaction stress term was constructed. Secondly, to solve the difficulty of integrating easily due to the complexity and irregularity of the integration region in space, Delaunay tetrahedra were introduced within the 3D Voronoi element for mesh refinement. It simplified the integration process. Finally, to verify the accuracy and efficiency of the 3D VCFEM model, comparative models of 3D VCFENM and FEM were established for analysis and discussion. The stress field and strain field were compared and analyzed for the first time. An example was also given for the presence of a large number of randomly distributed inclusion particles. The results showed that under the same accuracy, 3D VCFEM had the advantages of convenient mesh delineation and high computational efficiency compared with FEM, which provided a new way of thinking to analyze the actual PCRs.

Long-duration vehicles in near space have achieved great success; however, the non-destructive testing (NDT) methods for the envelope materials of such long-duration vehicles remain blank. In this paper, we propose the air-coupled ultrasonic NDT method theoretically. In the theoretical analysis process, the envelope material is simplified as an orthogonal sandwich structure. To calculate the displacement and stress fields of each medium, the state vectors are established and the transfer matrices of the material from the upper interface to the lower interface are obtained by using boundary conditions. Then, linear equations about the amplitude of reflected and transmitted waves are derived by combining the coupling boundary conditions of air and solid. The effects of incident angles, inflation of the envelope material, and debonding of the interfaces on the transmission coefficients are considered. The results show that the air-coupled ultrasonic NDT of the envelope material can be carried out in the pre-inflated state. Finally, a method for identifying interface debonding is proposed based on judging transmission coefficients within a certain frequency range.

In this paper, the free vibration and stationary stochastic response of functionally graded (FG) rectangular plates with varying thickness in supersonic flow and thermal environment are analyzed. Two types of material property variations of FG plates with varying thickness are considered: the variation along the direction perpendicular to the mid-surface and that along the direction perpendicular to the bottom surface. Considering the effects of aerodynamic pressure and thermal load, the governing equations of motion of FG plates with varying thickness are derived using Hamilton’s principle within the framework of first-order shear deformation theory. A meshfree Jacobi radial point interpolation (Jacobi-RPI) shape function is constructed by combining the Jacobi polynomials and radial basis to approximate the displacement components of the plate. The accuracy and reliability of the present approach are confirmed through sufficient comparisons with numerical results from the published literature and the finite element software ABAQUS. Finally, the effects of different parameters on the free vibration and stationary stochastic response of FG plates are investigated.

FeMnSi-based shape memory alloys (SMAs) have great applied potential to large-scale structures in civil engineering, especially as an aseismic structural material. Low-cycle fatigue performance is one of the most important properties of FeMnSi-based SMA aseismic materials. However, the low-cycle fatigue behavior of such SMAs, especially the stress-controlled low-cycle fatigue behavior (with ratchetting effect), has not been clearly understood. In this work, the low-cycle fatigue behavior of the FeMnSiCrNi SMAs subjected to stress-controlled cyclic tension–compression loads is investigated, and the effects of temperature, loading frequency, stress amplitude, and stress ratio are addressed. By analyzing the cyclic stress–strain response, fatigue fracture surface morphology, dissipation energy, ratchetting strain, and equivalent damping ratio, the mechanisms behind the temperature-, loading frequency-, stress amplitude-, and stress ratio-dependent low-cycle fatigue behavior are discussed. The results show that the plasticity, martensitic transformation, and/or the ratchetting strain caused by their tension–compression asymmetry are the decisive factors affecting the low-cycle fatigue behavior of FeMnSiCrNi SMAs.

The purpose of this paper is to make an assessment on the performance of a fiber reinforced plastic (FRP) helmet-head system subjected to ballistic impact. Firstly, a finite element (FE) model for the human head is developed. Constitutive models for each component of the head are determined and, in particular, strain rate effects of the compact bone of the skull and the hyperelastic property of the scalp are taken into account for the first time. Secondly, an FE model for Kevlar fiber reinforced plastic (KFRP) helmet is constructed based on the personal armor system for ground troops (PASGT) helmet. Recently developed dynamic constitutive models for metals and FRP laminates are employed for full metal jacketed (FMJ) bullet and the KFRP helmet. Finally, both the head and the helmet models are validated against available test data. Furthermore, the effects of various factors such as padding system, impact position, and projectile type on the ballistic performance of the helmet-head system have been systematically investigated with special attention being paid to the severity of head injury. It is found that the performance of the helmet with OA foam is advantageous over that of the helmet with strap-netting in head injury prevention. It is also found that a lower velocity (358 m/s) FMJ bullet poses more threats to head injury than a higher velocity (610 m/s) fragment-simulating projectile for the PASGT helmet-head system.

In order to realize the automatic recognition and classification of cracks with different depths, in this study, several deep convolutional neural networks including AlexNet, ResNet, and DenseNet were employed to identify and classify cracks at different depths and in various materials. An analysis process for the automatic classification of crack damage was presented. The image dataset used for model training was obtained from scanning experiments on aluminum and titanium alloy plates using an ultrasonic phased-array flaw detector. All models were trained and validated with the dataset; the proposed models were compared using classification precision and loss values. The results show that the automatic recognition and classification of crack depth can be realized by using the deep learning algorithm to analyze the ultrasonic phased array images, and the classification precision of DenseNet is the highest. The problem that ultrasonic damage identification relies on manual experience is solved.

This study investigates the structural, electronic, vibrational, and mechanical properties of cubic InTe using density functional theory and density functional perturbation theory. The results reveal the metallic character of cubic InTe, as indicated by its electronic structure and density of states. The dynamic stability of the material is confirmed by phonon dispersion analysis, with no imaginary frequencies observed. The Debye temperature (172.276 K) and melting temperature (1092.832 K) suggest excellent thermal resistance. A shear modulus of 18.20 GPa, Poisson’s ratio of 0.343, and Pugh’s ratio ((B/G)) of 2.87 support mechanical stability and indicate ductility. Isotropic dielectric properties, with Born effective charges of −3.768 for both In and Te atoms, highlight potential ferroelectric applications. These findings emphasize InTe’s suitability for electronic and construction applications.