Acta Mechanica Solida Sinica最新文献

This paper presents a novel fully edge-based smoothed finite element method for free vibration analysis of functionally graded plates, incorporating a quasi-weak form of smoothed integral within an edge-based finite element method framework. Employing first-order shear deformation plate theory, the present method accounts for transverse shear strain and rotary inertia effects while addressing exponentially graded material properties along the plate thickness. The formulation integrates a three-node Mindlin plate element (MIN3) with a shear stabilization technique to prevent shear locking. The quasi-weak form of smoothed integral necessitates the evaluation of indefinite integrals for shape functions, effectively tacking domain integrals related to the shape functions without partial derivatives. By applying both quasi-weak form of smoothed integral and strain smoothing technique, all domain integrals in stiffness and mass matrices are converted into boundary integrals over smoothing domains. Therefore, isoparametric mapping and computing of Jacobian matrix are completely eliminated throughout the solution process. The natural frequencies obtained using the present method are in good agreement with those reported in the literature, highlighting the versatility of the present method for free vibration analysis of functionally graded plates. Notably, the present method demonstrates advantages in eliminating shear locking and reducing sensitivity to mesh distortion.

The recovery stress of materials has a great potential application in the field of road crack self-repair, composite material self-repair, and so on. Taking into account the diversity of practical application environments, the recovery stresses of constrained shape memory alloy (SMA) materials in the initial state of austenite and twinned martensite are given respectively in this paper. As for the experimental research, the austenitic SMA is loaded and constrained. The recovery stresses at different stages are observed by increasing the temperature. In terms of the theoretical research, constitutive models with the initial state of austenite and martensite are established respectively based on the one-dimensional macroscopic phenomenon theoretical model and constraints of SMA. These constitutive models can describe the relationship between recovery stress and volume fraction of martensite under temperature loading with different pre-strains. The theoretical model and experimental data in this paper can provide specific support for the practical engineering application of SMA recovery stress.

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.

To address the challenges associated with multi-sided shells in traditional isogeometric analysis (IGA), this paper introduces a novel isogeometric shell method for trimmed CAD geometries based on toric surfaces and Reissner–Mindlin shell theory. By utilizing toric surface patches, both trimmed and untrimmed elements of the CAD surfaces are represented through a unified geometric framework, ensuring continuity and an accurate geometric description. Toric-Bernstein basis functions are employed to accurately interpolate the geometry and displacement of the trimmed shell. For singularities and corner points on the toric surface, the normal vector is defined as the unit directional vector from the center of curvature to the corresponding control point. Several numerical examples of polygonal shells are presented to evaluate the effectiveness and robustness of the proposed method. This approach significantly simplifies the treatment of trimmed shell IGA and provides a promising solution for simulating complex shell structures with intricate boundaries.

This paper presents a novel surface model based on the Gurtin–Murdoch theory and Kerr-type differential relations, which is established and numerically simulated. By employing the principles of equivalent force and mechanical equilibrium, a differential equation for the contact pressure-deflection relationship between a rigid indenter and an elastic thin beam is derived. The study investigates pressure distribution within the contact area and deformation patterns outside this region. The relationship between indentation parameters is analyzed from two perspectives: clamped and simply-supported boundaries, with a detailed comparison to classical cases. The findings reveal that the normalized contact pressure and load–displacement relationship of elastic thin beams are influenced not only by the half-width ratio and indentation depth but also by the material’s surface elasticity. Similar to classical contact scenarios, an increase in surface elasticity leads to the separation of the indenter from the beam’s center when the contact half-width exceeds a certain threshold (e.g., a ratio of 4 to the beam thickness). This results in a negative normalized contact pressure and the formation of two independent, symmetric contact strips. Notably, the relationship between displacement and contact half-width remains largely unaffected by surface elasticity, aligning with classical indentation contact results. The methodology and outcomes of this research provide a foundation for analyzing the structures and properties of nanostructured materials, offer insights for the design of future nanostructured devices, and present innovative approaches to addressing practical engineering challenges.

In pressurized nuclear power plants, metallic tubes such as steam generator (SG) tubes are subject to complex mechanical and environmental loads that can lead to crack initiation and propagation. Evaluating the structural integrity of SG tubes requires non-destructive assessment of crack size and location. Current inversion schemes can determine crack shape but lack position information, and reconstruction using a single coil has low efficiency. While array probes improve defect detection, reconstruction research based on array signals is challenging due to the complexity of processing multiple sets of signals. This study proposes a simple and effective array reconstruction scheme utilizing signals from two adjacent coils near the crack, enabling simultaneous determination of both crack shape and location through interpolation techniques. Numerical results validate this new crack sizing method, showing accurate reconstruction of both size and location.

Multi-cell structures and corrugated tubes illustrate excellent energy absorption capacities. Besides, bamboo with continuously changing contours demonstrates superior impact-resisting capacities. As a result, a bionic multi-cell double corrugated (BMDC) tube, inspired by Buddha bamboo, is investigated to assess whether it is an ideal energy absorber candidate. Compared to a corrugated tube, a BMDC contains an outer structure, an inner structure, and diaphragms, which are like webs bridging the inner and outer structures. A basic numerical model is correlated using a physical experiment, followed by an investigation of BMDC tubes’ energy absorption performance under axial loading, considering thickness and mass effects. Results indicate that the EA, MCF, and SEA of a BMDC containing 5 diaphragms (BMDC-5) with a 1.5 mm thickness can improve their respective responses by 112.89, 112.89, and 83.32% higher compared to a BMDC with no diaphragm (BMDC-0). In addition, the BMDC-5 with 0.156 kg mass generates the highest EA, MCF, and SEA, which is 79.78% higher than a BMDC-0 with the same mass. The parametric analysis illustrates that diaphragms’ amplitude and diameter have a decisive influence on energy absorption characteristics. This study emphasizes that BMDC tubes are innovative and practical, possessing excellent energy absorption performance.

The advantages of guided wave detection, such as its ability to propagate over long distances and penetrate deeply, have led to its application in the field of anisotropic damage detection in carbon fiber-reinforced polymer (CFRP). Due to the anisotropy of CFRP, traditional guided wave-based detection methods have difficulty in precisely locating the defect. In this study, we proposed a novel deep learning-based detection method for CFRP by employing image recognition technology for guided wave field inspection. This method is capable of rapidly and accurately extracting defective features from the structure, thereby facilitating precise damage identification. To avoid time-consuming sample data generation by simulation for CFRP, the steady-state guided wave field of the aluminum plates was simulated instead. The isotropic wave field data were then stretched and applied for neural network training.