Mojia Huang

This study primarily investigates the mechanical performance of prestressed anchor foundations. Based on the assumptions of continuity, homogeneity, and isotropy of the anchor foundation and anchoring materials, a simplified elastic analysis model was developed. Using the superposition principle, the working stresses under vertical loads and bending moments were calculated, allowing for the determination of the maximum working stresses within the anchors and the foundation. Additionally, the distribution of bond strength of the prestressed tendons was analyzed, and the concept of effective anchorage length was introduced. The reliability of the model was validated through prototype testing, with the measured free segment strain values showing a high degree of consistency with theoretical calculations, with errors within 6.5%. Empirical data on ultimate bearing capacity and bond characteristics were also obtained. By integrating numerical calculations with experimental results, the performance of the anchoring system under extreme and specialized loading conditions was analyzed. The experimental results indicated that the failure modes of all anchor foundations were characterized by bond failure at the interface between the anchor and the surrounding rock mass. Based on the experimental data, a reasonable anchorage length satisfying design strength requirements was proposed. The findings provide a theoretical foundation and practical guidance for the design and application of prestressed anchor foundations in structures such as wind turbine towers.

Most metal plates are orthorhombic aggregates of cubic crystallites. First, we discuss the representations of the stress tensor, the strain tensor, the elasticity tensor, and the rotation tensor under the Kelvin notation. Then, we give the decomposition of determining the material constants and the mesostructure tensors on the metal plate of cubic crystallites. Under the Voigt model and the Reuss model, we derive the volume average stiffness tensor and the volume average flexibility tensor’s inverse, respectively, of cubic crystallites based on the decomposition. The elasticity tensors of the Voigt model and the Reuss model are upper and lower bounds of the effective elasticity tensor, respectively. We make use of an FEM example to check the decomposition of the elasticity tensor on the material constants and the mesostructures. The results of our decomposition are consistent with the FEM simulation’s results.

Uneven settlement of transmission tower foundations can result in catastrophic events, such as tower collapse and line failures, disrupting power transmission operations. To address the challenging repairs caused by uneven foundation settlement of transmission towers, we propose an adjustable foundation bolt (AFB). This paper provides a detailed theoretical analysis of the AFB’s stability and load-bearing capacity, including critical buckling force formulas and maximum normal stress expressions. Finite element simulations confirm the precision of our theoretical formulations. Additionally, we introduce a method using baffles to enhance its load-bearing capacity, analyzing the impact of different numbers of baffles through numerical simulations. The experimental results validate the effectiveness of baffles in enhancing structural load-bearing capacity. The device brings convenience and efficiency to the maintenance of transmission towers.

The integrity of large crossing cables is frequently compromised by inland river ultra‐high sand dredgers, leading to severe safety incidents. To mitigate these risks, height‐limiting mechanisms, known as river‐blocking lines, are essential on both sides of the large crossing cable. Traditional river‐blocking lines are typically rigid structures, posing challenges for both the river‐blocking line and passing ships. To address this issue and enhance safety measures, this study introduces a novel flexible blocking device. Initially, the fundamental principles of suspension cable theory are employed to design the river‐blocking line. By leveraging energy conversion principles, heavy objects are suspended at the cable ends to convert the kinetic energy of oncoming ships into potential energy during collisions. Subsequently, a structural model for a three‐suspension cable river‐blocking line is developed. Finite element simulations confirm the model’s efficacy, aligning with theoretical expectations. Furthermore, a scaled prototype of the model is constructed to assess project feasibility and reliability. The results affirm that the flexible blocking device can serve as an effective height‐limiting mechanism, proficiently impeding passing ships, mitigating impact loads, safeguarding vessels, and offering direct physical protection for ultra‐high voltage (UHV) large‐span cables.

Springs are fundamental components in mechanical systems, crucial for ensuring the safety and functionality of mechanisms. Timoshenko’s stiffness formula accounts for both bending and torsional energy effects, providing accurate results for small deformations. However, when the deformation becomes large, the spring stiffness becomes a nonlinear problem due to the changing inclination angle and radius during deformation. In this study, we derive a formula for the cylindrical spring stiffness under nonlinear large deformation by considering two assumptions: the invariability of the polar angle at any point and spring wire length during deformation. This formula incorporates the effects of inclination and radius changes on the spring wire. We analyze the stiffness of the cylindrical spring with different initial inclinations using the finite element method (FEM). FEM results were compared with those obtained from Timoshenko’s formula, Hiroyuki’s formula, and the derived formula. For small deformations, the FEM results matched well with all three formulas. However, for nonlinear large deformations, the calculated results from Timoshenko’s formula showed a discrepancy of up to 32.58% compared to the FEM results. The modified Hiroyuki formula also exhibited slightly poorer agreement with the FEM results than the formula proposed in this paper. On the other hand, our derived formula demonstrated excellent agreement with the FEM results for nonlinear large deformations. Therefore, our stiffness formula for cylindrical springs is recommended for mechanical engineering spring design applications involving nonlinear large deformations.

The thermal conductivity of thermal insulation materials directly affects the building energy consumption. The types and constituents of thermal insulation materials in thermal insulation boards are the key to determining the insulation performance. By optimizing the material constituents and ratios, this paper proposes an improved graphite composite insulation board (GCIB), which has lower thermal conductivity and good fire resistance. Through theoretical derivation, it is found that the limit range of the thermal conductivity of the new GCIB is 0.042–0.064 W/(m · K). Combined with the results of theoretical value analysis, and according to the ratios of material components, the random distribution function of each material component is constructed, and the numerical model of GCIB is established. Through numerical analysis, the range of thermal conductivity of the new composite insulation board is 0.046–0.050 W/(m · K). Finally, we establish an experimental model of the new GCIB. Through the model test of six GCIBs, the thermal conductivity of the new GCIB is obtained as 0.046 W/(m · K), which is in good agreement with the results of theoretical analysis and numerical simulation. Through theoretical analysis, numerical simulation and a sample test, this paper verifies the better thermal insulation performance of the improved GCIB, providing theoretical and numerical simulation methods for the new GCIB, as well as a theoretical reference for the promotion and application of the GCIB.

The grain shape and orientation distribution of metal sheets at mesoscales are usually irregular, which has an impact on the elastic properties of metal materials. A grain shape function (GSF) is constructed to represent the shape of grains. The expansion coefficient of GSF on the basis of the Wigner D function is called the shape coefficient. In this paper, we study the influence of average grain shape on the elastic constitutive relation of orthogonal polycrystalline materials, and obtain a new expression of the elastic constitutive relation of polycrystalline materials containing grain shape effects. The seven string method is proposed to fit the shape of irregular grains. Experiments show that the GSF can better describe the shape of irregular grains. Using the microscopic images of the grains, we carried out the experimental measurement of micro and macrostrain at grain scale. The experimental results show that the grain shape parameter (slenderness ratio) is consistent with the theoretical results of the material macroscopic mechanical properties.

A new Drucker yield function for an orthorhombic aggregate of cubic crystallites is proposed. The related function κ(η) between the Drucker yield function and the Hershey yield function is determined. The Drucker yield function and the Hershey yield function with the related function κ(η) have good consistency. We get the yield stresses and the q-values of isotropic polycrystals from the Drucker yield function and the Hershey yield function under the biaxial tensional stretching. In the case of anisotropy, the uniaxial yield stress and q-value with effects of the texture coefficients and {the directional dependence} are derived from the new Drucker yield function. The parameters Y_iso,κ ) can be determined by{ fitting the data of the Taylor--Bishop--Hill theory }under the biaxial tensional stretching. The material parameters (β,γ) are obtained by fitting the yield stress and the q-value of the Taylor--Bishop--Hill theory }under the uniaxial tensional stretching. The new Drucker yield function for the orthorhombic aggregate of cubic crystallites can precisely reproduce the predictions of the Taylor--Bishop--Hill theory. The plastic yield stress Y_θ and the q-value q_θ based on the new Drucker yield function under the uniaxial tensional stretching can fit the experimental data Y_i, q_i) of steel sheets and aluminium sheets very well. The material parameters (Y_iso, βc⁴_m0,γc⁴_m0) of the new Drucker yield function are determined via the experimental data.