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This review is dedicated to balancing methods that are used to solve the rotor-balancing problem. To ensure a stable operation over an operating speed range, it is necessary to balance a rotor. The traditional methods, including the influence coefficient method (ICM) and the modal balancing method (MBM) are introduced, and the research progress, operation steps, advantages and disadvantages of these methods are elaborated. The classification of new balancing methods is reviewed. Readers are expected to obtain an overview of the research progress of existing balancing methods and the directions for future studies.

For large flexible parts with initial deformation, the springback deviation of a product often occurs with the release of the fixture constraints after assembly. Different final constraint states of product leads to different springback deformation. In order to solve the problem that the classical method of influence coefficient (CMIC) is single to the final constraint states of the product in the assembly deviation modeling of flexible parts, an improved method of influence coefficient (IMIC) based on unit displacement response is proposed in this paper, which can meet the assembly springback deviation analysis of the product under any final constraint states. On this basis, a modeling method of assembly deviation of large flexible parts is proposed, which can accurately and efficiently predict the assembly deviation of flexible parts with initial deformation. Through case comparison and analysis, the IMIC has the same calculation accuracy as the CMIC, and the analysis steps of deviation model based on the IMIC are reduced by 66.67% and the analysis time is shortened by 54.17%, which proves the efficiency of the method proposed in this paper. Compared with the CMIC, the method proposed in this paper is more applicable and universal.

The goal of this article is to conduct a detailed study of China’s forestry industry chain and determine the effect it has on the national economy. Based on the 2018 China Input–Output Table (153 departments) and other relevant data released by the National Bureau of Statistics, as well as the input–output method established by Wassily Leontief, this article conducts a comprehensive and detailed analysis of China’s forest industry chain and its impact on the national economy. The results show that the backward industrial chain of China’s forestry industry involves 105 industrial departments. China’s forestry sector purchases the most products from the tertiary industry, accounting for 56.05% of all forestry purchases. The products of the tertiary industry have a significant impact on forestry. The forward industry chain of China’s forestry involves 131 industrial sectors, with China’s forestry selling the most products to the secondary industry, accounting for 93.47% of all forestry sales. The forestry sensitivity coefficient is 0.767 and the influence coefficient is 0.65. The secondary industry has a significant impact on the sales of forestry products. The impact of the forward industry chain is greater than that of the backward industry chain and the impact of forestry on the national economy is quite large. Suggestions about how to expand the planting area and production scale of domestic economic forests were put forward. An increase in the added value of exported forestry products, improved service quality of the tertiary industry to forestry, and improved quality and quantity of products provided by forestry to the secondary industry are necessary.

Joint deformation greatly influences machining accuracy for a robotic arm. In this paper, the deformation characteristics of the robotic arm with hybrid kinematic chains are investigated to improve its machining accuracy. Firstly, the deformation model of the joints has been established based on the Strain energy method and Castigliano theorem according to the robot structure. Secondly, the deformation influence coefficient (DIC) is defined to investigate the deformation influence of main components on the end-effector, and the deformation characteristics are evaluated by the simulation. Finally, a small size robotic arm prototype is established and robotic drilling comparative experiments are conducted. The theoretical and experimental results show that the machining method can be selected according to the DIC, in which the force can be applied to the components with better stiffness. On the other hand, the deformation of driving components can also be reduced when the DIC cannot be adjusted to meet the accuracy requirement.

Three-dimensional spatial effects in deep excavations critically govern the mechanical response of retaining structures and adjacent soils, yet their quantitative characterization remains a challenge. This study systematically investigates the spatial behavior of row-pile-supported foundation pits through an integrated approach combining model tests, theoretical analysis, and numerical simulations. A novel formulation for the spatial effect influence coefficient K is derived from limit equilibrium principles and subsequently validated via ABAQUS-based finite element simulations. Model test results reveal pronounced spatial heterogeneity in earth pressure and bending moment distributions along the pit perimeter: lateral earth pressure at corner regions exceeds that at mid-side locations at equivalent depths, whereas bending moments in mid-side piles are substantially larger than those at corners. Displacement field measurements further demonstrate that corner zones, constrained bidirectionally, undergo minimal deformation, while maximum displacement occurs at the midpoints of the long sides. These observations collectively confirm the existence of a marked corner effect and a subdued side-midpoint effect under three-dimensional confinement. Complementary numerical analyses indicate that the coefficient K decreases monotonically with increasing half-angle corners and distance from the corner, thereby quantitatively capturing the decay of spatial constraint intensity. Together, these findings establish a theoretical framework for assessing excavation-induced spatial effects and provide actionable guidance for the rational design of deep foundation pit support systems.

A numerical approach is presented to simulate the combined effect of pressure, temperature, roughness and cavitation in the hydrodynamic plain journal bearing. The oil film temperature within the bearing increases because of shearing action. Consequently, the viscosity of lubricant reduces and hence the load capacity of the bearing decreases. Therefore, thermoelastohydrodynamic analysis of journal bearing is essential for better estimation of bearing performance. Finite difference method (FDM) is used to discretise the governing equations. Elastic deformation is obtained by influence coefficient method. Influence coefficient matrix is calculated through finite element method. Further, hydrodynamic pressure is determined by solving the three equations, namely Reynold’s equation, film thickness equation and energy equation, which are solved through FDM. Effect of surface roughness on pressure, temperature, friction and oil flow is studied. Results are compared with the existing published work and are in good agreement with it. There is a marginal increase in bearing deformation value with increase in eccentricity ratio up to 0.8, and there after a sharp rise is noticed for further higher eccentricity.

This paper presents a preliminary numerical investigation on the mechanical behavior under eccentric compression of T-shaped steel tube-steel reinforced concrete columns. A refined finite element (FE) model was developed in ABAQUS 2021 and validated against published axial compression test results. The effects of three key parameters (eccentricity, outer steel tube thickness, and built-in steel skeleton size) on the bearing capacity, failure mode, stiffness degradation, and stress distribution of the studied members were systematically analyzed via finite element analysis, followed by comparative calculations and an applicability analysis of the calculation of eccentric compression bearing capacity. All eccentric compression results presented herein were obtained through numerical simulation and have not been directly verified by physical tests. The results show that the ultimate bearing capacity decreases by more than 57% as the eccentricity increases from 0 mm to 75 mm, with the failure mode transitioning from axial compression failure to flexural failure. Within the studied parameter range, the 4 mm-thick outer steel tube exhibits superior comprehensive performance, including bearing capacity, stiffness, and ductility. Increasing the built-in steel skeleton size effectively enhances the flexural stiffness and ductility, and delays stiffness degradation. The existing code-specified formula demonstrates good accuracy (relative error < 6%) for e ≤ 50 mm but yields significant errors for e = 75 mm. An empirical expression for the equivalent eccentricity influence coefficient α is proposed, which reduces the overall average error from 4.89% to 2.26% within the parameter scope of this study.

The current analysis is an effort to obtain the vibration characteristics of a cantilever rotor shaft with an extra mass added at the free end of the rotor shaft partially immersed in a viscous medium. This work is concentrated on the theoretical analysis of the natural frequency and amplitude of the spinning cantilever rotor shaft with addition mass using the influence coefficient method. The influence of fluid forces is studied using the Navier–Stokes equation. The gap ratio (ratio of the fluid-filled container radius to the shaft radius) and viscosity of the fluid are taken as the main variable parameters.MATLAB programming is used to obtain vibration behavior from the theoretical expressions. The obtained result from the numerical analysis is validated by the comparison of the results of experimental analysis.

Carbonation can lead to reduction of alkalinity of concrete and initiation of steel reinforcement corrosion. In durability design of concrete structures, the carbonation depth should be duly considered. However, the concrete stress state would influence the carbonation depth, and there has been inadequate research on such effect. In this study, it is proposed to introduce a stress influence coefficient to the concrete carbonation depth model. With reference to the experimental data from eleven research studies in the literature encompassing both tensile and compressive stress states, the relationship between stress influence coefficient and concrete stress ratio is quantitatively investigated, and mathematical equations relating the stress influence coefficient with the concrete stress ratio are established. Comparative study with three typical existing groups of equations shows that the proposed equations of stress influence coefficient are more reasonable and have a higher reliability. The effects of carbonation time, mix proportions of concrete on stress influence coefficient are also analysed, and the magnitudes of the effects are found to be approximately within ±10%. Finally, the modified carbonation depth models are proposed and verified by the experimental data, which suggests that the proposed models are of desirable accuracy. Adoption of the proposed equations as the modified formula of stress influence coefficient in the concrete carbonation depth model for practical applications is recommended.

Flutter was encountered at part speeds in a scaled wide chord fan blisk designed for a civil aeroengine during a rig test when the fan bypass flow was throttled toward its stall boundary. Analysis of the blade tip timing measurement data revealed that the fan blades vibrated at the first flap (1F) mode with nodal diameters of two and three. To facilitate a further rig test and ultimately eliminate the flutter problem, a numerical campaign was launched to help understand the root causes of the flutter. Both the influence coefficient method (ICM) and the traveling wave method (TWM) were employed in the numerical investigation to analyze unsteady flows due to blade vibration, with the intention to corroborate different numerical results and take advantage of each method. To eliminate nonphysical reflections, a sponge layer with an inflated mesh size was used for the extended inlet and outlet regions. Steady flow field and unsteady flow field were examined to relate them to the blade flutter. The influences of vibration frequency, mass flow rate, shock, boundary layer separation and acoustic mode propagation behaviors on the fan flutter stability were also investigated. Particular attention was paid to the acoustic mode propagation behaviors.