Structural Design Analysis Research Articles

A numerical algorithm for damage progression of reinforced concrete bridge piers during air temperature and solar radiation cycles

Reinforced concrete (RC) solid piers are unavoidably affected by air temperature changes and solar radiation during service life. Nevertheless, the deterioration of pier concrete with increased exposure age remains unclear. A novel thermal-mechanical numerical algorithm (finite element model) for characterizing the deterioration characteristics of RC structures under cyclic environmental loads has been suggested. The deterioration of RC pier concrete after 100 years of air temperature and solar radiation cycles is simulated. The numerical results demonstrate that tensile damage of pier concrete during air temperature and solar radiation cycles increases continuously with exposure age. After one year of exposure, the tensile damage value of pier surface concrete increased to 0.201 and further increased to 0.286 and 0.357 as the exposure age grew to 10 and 100 years. Pier concrete tensile damage can be mitigated by using surface short-wave absorption-reducing methods, controlling the thermal properties of concrete, and raising the concrete peak tensile strain. The proposed finite element framework and numerical solutions enable a viable simulation-based method for the analysis of bridge structural long-term deterioration behavior and design of the bridge engineering.

Structural Design and Flight Simulation of Firefighting and Rescue UAV Based on Coaxial Dual Rotors

The technology of firefighting unmanned aerial vehicles (UAVs) used in fire scene reconnaissance, water disaster investigation, and rescue missions, has become a crucial asset in responding to fires and emergencies. The key to this technology is to swiftly and effectively improve the operational efficiency of UAVs. Based on the premise of rapid and effective rescue, the stability, tracking, and safety of hexacopter UAVs technology improved the design and optimization innovative design of the storage and transportation convenience structure of unmanned aerial vehicles were carried out. An innovative high-pressure ejection mechanism for fire bombs (delivery items) has been designed. So, a portable, efficient, and fast unmanned aerial vehicle structure was designed. The PX4 flight control system was used to conduct simulation experiments on the newly designed UAV, and it was found that the structural design was reasonable, and the UAV was operated smoothly and accurately during the simulation flight. This structural design and simulation analysis can provide new ideas for the design of new fire-fighting equipment.

Dynamic viscoelastic properties of ultra-large particle size asphalt mixture based on fractional derivative constitutive model

The aim of this paper was to accurately grasp and precisely characterize the dynamic viscoelastic properties of Ultra-Large Particle Size Asphalt Mixture (LSAM-50), and fully explore the features and simplified forms of the generalized fractional derivative Zener (GFDZ) model. The constitutive relations of the GFDZ model with n Abel elements were first given, and a modified GFDZ (mGFDZ) model was proposed. Then the master curves of LSAM-50, AC-13 and AC-20 mixtures were constructed, and the expression effects of different models and the dynamic viscoelastic behaviors of different asphalt mixtures were compared. The results showed that LSAM-50 was a typical viscoelastic material similar to traditional mixture. Both dynamic modulus and energy storage modulus decreased with increasing temperature. The phase angle increased first and then decreased with temperature increasing, and the peak value appeared near 40℃ at low frequency. The loss modulus increased first and then decreased with the temperature increasing. When the loading frequency was 0.1 Hz∼25 Hz, the peak value appeared at 0℃∼20℃. The rutting factors of LSAM-50 became larger with temperature reduction and frequency enhancement. When the number of Abel elements reached 2 in the GFDZ model or reached 3 in the mGFDZ model, the model fitting effects would no longer change significantly. The 2-mGFDZ model with only 5 parameters fitted master curves data satisfactorily and the physical meanings of parameters were clear. Comparing among three mixtures, LSAM-50, with the lowest asphalt content, showed significantly superior elasticity and better deformation resistance at medium and high temperatures. At low temperatures, the viscosity behavior of LSAM-50 was slightly inferior, but it may have pronounced plate properties considering the effect of aggregate skeletonization. The research results would promote new pavement structural design and mechanical response analysis.

Design and numerical analysis of perforated plate lattice structures

The plate lattice structure, a novel mechanical metamaterial, surpasses traditional truss lattice structures in stiffness and strength. However, its closed-walled topology poses challenges for manufacturing using powder or liquid-based additive manufacturing methods. This study addresses this issue by focusing on designing manufacturable plate lattice structures with various perforations. Through numerical simulations, we conducted a parametric study to investigate how different perforations influence the stiffness, isotropy, strength, and buckling resistance of the plate lattice structures. The results demonstrate that perforated plate lattice structures maintain higher stiffness compared to the traditional stretching-dominated octet truss lattice. The degree of stiffness deterioration is dependent on the geometry of the perforations. While plate lattice structures exhibit high stiffness at an extremely low relative density of 0.009, their strength is limited by premature elastic buckling. In contrast, at this relative density, the octet truss lattice demonstrates much greater strength. Interestingly, the introduction of perforations improves the plate lattices’ buckling resistance as compared to the unperforated design. With an increase in relative density, the plate lattices’ yielding mechanism shifts from elastic buckling-dominated to material plasticity-dominated. Moreover, when compared to other lattice structures in literature, it becomes evident that perforated plate lattice structures exhibit superior stiffness and strength, underscoring their considerable potential. The perforated lattices designed in this study contribute to the advancement of infill structures applicable in additive manufacturing and expanding the current state of the art in this field.

Systematic analysis of Structural optimization design of post-disaster emergency rescue robot

Systematic analysis of Structural optimization design of post-disaster emergency rescue robot

Application of laced built-up columns with cold-formed lipped angle sections in wind turbine towers

Increasing the height of wind turbine towers effectively enhances their power output. Consequently, there is a growing demand for constructing wind turbine towers with higher hubs, especially in heavily populated and energy-intensive areas. Traditional approaches involve enlarging angled steel, posing production challenges and economic feasibility concerns. This study proposes replacing traditional angled steel with cold-formed lipped angles for improved structural performance. In this paper, a finite element model of the built-up column with cold-formed lipped angles is developed through ANSYS software. Finite element calculations are applied to various cross-sectional dimensions of cold-formed lipped angle sections to analyze column curves. Incorporating calculation methods from international standards, the paper presents a fitting formula and calculation method for the load-carrying capacity of the built-up column with cold-formed steel lipped angle sections. Finally, utilizing a wind turbine tower with a 120 m hub height as a case study, the paper conducts structural modeling and design analyses for both the built-up column with cold-formed lipped angles and the one with conventional angled steel. The research indicates that after adopting the built-up column with cold-formed lipped angle sections, the stress ratio of the tower columns is significantly reduced, with an approximate 16 % decrease in the stress ratio of the most critical section. The adoption of cold-formed lipped angle section effectively enhances the overall load-carrying capacity of the wind tower, providing a greater safety margin for the design. The calculation method provides valuable insights for future engineering applications.

Design and mechanical performance analysis of T-BCC lattice structures

The Body-Centered Cubic (BCC) lattice structure is commonly used in high-end equipment fields, such as aerospace, due to its superior mechanical properties, lightweight characteristics, and ease of processing. However, there is a need to improve the performance-to-weight ratio of the traditional BCC lattice structure. This study utilizes topology optimization to design a T-BCC lattice structure based on the BCC unit cell, with the aim of maximizing stiffness. A model proposing the characterization of the Young's modulus of BCC lattice structures is presented. The model is based on calculations of cell porosity and beam stress analysis, assuming a large cell. This approach indirectly enables the calculation of the Young's modulus of T-BCC lattice arrays in multiple dimensions. Simulation and experimental comparison were used to analyze the compressive performance and load-bearing modes of T-BCC lattice structures, revealing the mechanisms of compressive deformation and failure modes. The accuracy of the characterization model for Young's modulus was found to be 93.1%. Compared to BCC lattice structures designed by traditional methods, T-BCC lattice structures designed via topology optimization can increase the Young's modulus by up to 36% and yield strength by 37.2%. This suggests that T-BCC lattice structures are a more lightweight and efficient solution for designing components in high-end equipment fields.

Design, Synthesis and Proteomics-Based Analysis of Novel Triazinone Derivatives Containing Amide Structures as Safer Protoporphyrinogen IX Oxidase Inhibitors.

Resistant weeds severely threaten crop yields as they compete with crops for resources required for survival. Trifludimoxazin, a protoporphyrinogen IX oxidase (PPO) inhibitor, can effectively control resistant weeds. However, its crop safety record is unsatisfactory. Consequently, a scaffold-hopping strategy is employed in this study to develop a series of new triazinone derivatives featuring an amide structure. Most compounds depicted excellent herbicidal activity across a broad spectrum at 37.5-150 g ai/ha, among which (R)-I-5 was equivalent to flumioxazin. (R)-I-5 demonstrated significant crop tolerance to rice and wheat, even at 150 g ai/ha. (R)-I-5 exhibited superior pharmacokinetic features compared to flumioxazin and trifludimoxazin. This was depicted by the absorption, distribution, metabolism, excretion, and toxicity predictions. Notably, proteomics-based analysis was applied for the first time to investigate variations among plant proteins before and after herbicide application, shedding light on the conservative and divergent roles of PPO.

Stress-dependent Mohr–Coulomb shear strength parameters for intact rock

Rock strength is imperative for the design and stability analysis of engineering structures. The Mohr–Coulomb (M-C) criterion holds significant prominence in geotechnical engineering. However, the M-C criterion fails to accurately capture the nonlinear strength response and neglects the critical state of rocks, potentially leading to inaccuracies in the design phase of deep engineering projects. This study introduces an innovative stress-dependent friction angle and cohesion (SFC) for the M-C criterion to capture the nonlinear strength responses of intact rocks, spanning from non-critical to critical states (brittle to ductile regions). A novel method for determining these stress-dependent parameters at each corresponding σ3\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\sigma_{3}$$\\end{document} is initially introduced. Subsequently, an examination of the confinement dependency of the friction angle and cohesion is conducted, leading to the derivation of the SFC model. The SFC-enhanced M-C criterion, utilizing parameters obtained from triaxial tests under lower σ3\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\sigma_{3}$$\\end{document}, demonstrates the capability to delineate the complete non-linear strength envelope from brittle to ductile regions. Validation through triaxial test data confirms that the predictions of the SFC-enhanced M-C criterion accurately correspond to the strength characteristics of the tested rocks.

Bond performance and constitutive model of steel bar in G-UHPC under cyclic loading

The increasing embrace of the low-carbon and environmentally sustainable construction approach has opened exciting opportunities for using environmentally friendly geopolymer based ultra-high-performance concrete (G-UHPC) in engineering structures, drawing significant attention to its performance. Seismic performance is a crucial factor in structural design, and it is greatly affected by the bond behavior between steel bar and concrete. As a result, a thorough understanding of the bond behavior of steel bars to G-UHPC provides essentially theoretical support for the structural design and nonlinear finite element analysis of G-UHPC structures, which is vital for their widespread implementation in earthquake engineering. This study tested 54 specimens from 18 groups to examine the bond performance of G-UHPC and steel bars under cyclic loading. The influence of concrete and steel bar types, protective layer thickness, bond length, and steel fiber on critical bond performance indicators were evaluated, and the bond stress-slip hysteretic and skeleton curves were analyzed. Subsequently, based on the experimental data, a constitutive model was proposed to predict the bond stress-slip relationship of steel bars and G-UHPC under cyclic loading. The results indicated that the steel bars exhibited superior bond performance with G-UHPC as compared to NSC. The bond and residual strength between steel rebars and G-UHPC was approximately 1.73 times and 3 times greater, respectively, in comparison with that between NSC and steel rebars. Increasing the strength of steel bars only resulted in a limited 2 % improvement in bond strength. The steel bar diameter, protective layer thickness, bond length, and the dosage and length of steel fibers in G-UHPC significantly influenced the bond performance. The addition of irregular-shaped steel fibers to G-UHPC has demonstrated potential in improving energy consumption, with the most remarkable enhancement observed for the inclusion of twisted steel fibers. Specifically, the incorporation of twisted steel fibers signally enhanced the energy consumption to approximately 1.3 times the energy dissipation as compared to straight steel fibers with the same dosage and aspect ratio. In addition, the accuracy of the proposed constitutive model has been validated.

Design and experimental study of a stepped magnetorheological damper with power generation

Traditional vehicle suspension magnetorheological dampers have problems with low output damping force and require additional energy input to operate, to improve the performance of the vehicle suspension magnetorheological damper, in this paper, we propose and investigate a stepped magnetorheological damper structure with power generation, and conducts structural design and magnetic circuit analysis. The effects of different currents, damping gaps, coil slot positions, and coil turns on the damping performance of the stepped magnetorheological damper with power generation are numerically studied. The magnetic circuit sensitivity analysis of the power generation structure and the magnetorheological damper structure is also performed. Experiments have verified the effects of different input excitations on damping and energy-feeding performance, and the results of numerical analysis have been verified. The results show that when the excitation coil is wound for 257 turns, the magnetic circuit requirements are met. And the influence of different amplitudes, frequencies, and currents on the output damping force was studied through experiments. The results showed that the damping force would increase with the increase of single parameter values. When the amplitude was 7 mm, the frequency was 1 Hz, and the current was 2 A, the output damping force could reach 4500 N, meeting the requirements for use.

Dynamic Modal Reanalysis Using Flexibility Disassembly Perturbation Method

In structural optimization design and reliability analysis, it is necessary to repeatedly modify the structure and calculate the corresponding vibration modal parameters. It will require significant computational costs if a complete analysis is used to calculate the vibration modes of each modified structure. In order to improve computational efficiency, this work develops a dynamic modal reanalysis method based on flexibility disassembly perturbation, which utilizes the modal data of the original structure to quickly calculate the modal parameters of the modified structure. The core idea of the proposed method is to use the flexibility matrix decomposition formula to quickly calculate the flexibility matrix after each modification of the structure and then obtain a high-precision reduced eigenvalue problem for solving the vibration modes of the modified structure. Three numerical examples are used to validate the proposed modal reanalysis method. It has been shown that the proposed method has higher computational accuracy and efficiency than the existing modal reanalysis method, especially for high-rank and large modification scenarios.

Structural design and preliminary feasibility analysis of a new stabilizing plate for the advanced tokamak in MD event

In tokamak devices, the stabilizing plates are installed in the vacuum vessel to mitigate the vertical instability of plasma. As the power and operating time of tokamak devices increase, the electromagnetic force generated by MD (Major Disruption) of plasma and thermal load will be greater than before. In order to maintain the performance of the stabilizing plate, a new concept about stabilizing plate for the advanced tokamak is introduced in this article. The new stabilizing plate is designed with a sturdy body and a composite cooling structure. Meanwhile, in order to reduce the contact resistance between stabilizing plates, an electrical connection structure is specially added for the stabilizing plate. Based on the electromagnetic analysis and thermal analysis, theoretical feasibility for the new stabilizing plate is provided. In order to verify the actual performance of the electrical connection structure, the contact resistance test is conducted. According to the experimental results, the total contact resistance of total stabilizing plates is less than 3.2 μΩ.

Design and control of a side dense transplanting machine for sweet potato seedlings on mulch film

At present, China is the leading country in sweet potato cultivation worldwide. However, there are still several problems such as high labor intensity, low efficiency of manual transplanting, and lack of machinery for side transplanting for sweet potato seedlings on mulch film. Therefore, a side dense transplanting machine for sweet potato seedlings on mulch film is designed, using a multi-row side transplanting method. It is mainly composed of a transplanting device, a seedling conveying device, a traveling device, and a control system. Based on the agronomic requirements for sweet potato transplanting, the study focuses on the structure and working principle of the complete machine. It involves the detailed structural design and motion analysis of the crank-rocker and cam of the transplanting device. Based on the sweet potato seedlings transportation plan, parameters such as the vertical height of the seedling conveying device, the size of the support frame, and the relative relationship between position of the transplanting device are determined. To ensure the smooth transplantation of sweet potato seedlings, the motor parameters required for each device are calculated and determined. An Arduino control system is developed to manage the coordinated movement of each device. Positioning components are integrated to ensure accurate coordination between the transplanting device and the seedling conveying device. This setup enables the seedling claws to pick sweet potato seedlings and perform the side transplanting on the mulch film. Field test results show the missed rate of seedlings, the qualified rate of transplanting and the qualified rate of transplanting depth are 4.13 %, 91.62 % and 93.86 % respectively. The transplant spacing coefficient of variation and the average spacing between seedlings are 1.90 and 177.06 mm respectively. All indicators of the transplanting machine meet the agronomic requirements for side dense transplanting for sweet potato seedlings on mulch film. The transplanting machine is integrated with sweet potato seedling transplanting agronomy, achieving mechanized transplanting of sweet potato seedlings, reducing labor intensity, and promoting the quality and efficiency of sweet potato production. This research provides a reference for the development of sweet potato seedlings transplanting equipment.

Structural design and surface networking analysis of a truss antenna based on hexagonal frustum deployable mechanism units

With the development of space technology, deployable mechanism has been widely applied in large aperture space antennas. In this paper, a hexagonal frustum deployable antenna unit and an innovative modular assembling concept are proposed for large parabolic truss antenna. Screw topology diagram and screw constraint matrix are established to solve degree of freedom (DOF) of the antenna mechanism. By separating column vectors of screw constraint matrix, whole actuations of antenna mechanism are obtained according to unique solution condition. A new hexagon antenna network method based on hexagon frustum units and rotation transformation matrix is proposed, and correctness and efficiency of the modeling principle are proved by simulation. Finally, a prototype of the proposed hexagonal frustum truss deployable antenna mechanism is constructed, and a deployment experiment is conducted, which demonstrate the mobility and deployment performance of the mechanism. The mechanism proposed in this paper provides a theoretical reference for the parabolic truss deployable antenna mechanism, which is potentially valuable in the application of large aperture deployable antennas.

Structural Design and Optimization Analysis of Multi-degree-of-freedom Motor Using Gas Bearing

Structural Design and Optimization Analysis of Multi-degree-of-freedom Motor Using Gas Bearing

Structural Design and Mechanical Analysis of HTS CICC Made From Twisted Stack Slotted-Core Cable

Structural Design and Mechanical Analysis of HTS CICC Made From Twisted Stack Slotted-Core Cable

Structural design and kinematic analysis study of ultrasonic flaw detection robot

Abstract A five-degree-of-freedom robot design scheme for liquid immersion ultrasonic flaw detection is proposed to address the challenges in complex surface ultrasonic flaw detection. To meet the requirements of underwater working environments, an XYZ+AB-type robot, which improves part of its structure, is adopted. A kinematic model of the robot is established using improved D-H parameters to obtain the forward and inverse kinematics of the robot. Based on the kinematic model, the simulation model of the robot is established by using the Matlab toolbox, which verifies the rationality of the design and the correctness of kinematics. The robot designed in this plan mainly targets thin-walled parts, such as aircraft skin and engine blades, with a repeat positioning accuracy of 0.01 mm and a detection speed of 120 mm/s. Compared with foreign high-degree-of-freedom penetrative flaw detection robots, the hardware cost of the robot in this plan can be reduced by half.

Structural design and finite element analysis of a milling machine sliding saddle

Abstract With the rapid development of modern manufacturing, the requirements for milling machine products are becoming higher and higher, leading to higher requirements for the working accuracy of milling machines. It is necessary to use the finite element method for static analysis of key components. This article uses 3D software to establish a geometric model of the milling machine saddle and establishes a finite element model. Finite element analysis is performed on the stiffness and strength of the sliding saddle in the middle of the crossbeam and the spindle sleeve at the lowest end of the sliding saddle under the load condition. Through analysis, it is known that the milling machine slide saddle is located in the middle of the crossbeam, and the spindle sleeve is located at the lowest end of the sliding saddle, which is the worst working condition. According to the strength theory, it is verified that its strength meets the requirements. This static analysis can provide reliable data for the design optimization of the milling machine saddle.

A fast analysis algorithm for structural vibration modal sensitivity

Vibration modal sensitivity analysis has a wide range of applications in structural optimization design, model correction, fault detection, and reliability analysis. The existing methods for calculating modal sensitivity mainly include modal superposition method, Nelson’s method, and some improved algorithms derived from them. However, the existing algorithms have the drawback of low computational efficiency when applied to modal sensitivity analysis of the large-scale structures. In view of this, the objective of this work is to develop a fast modal sensitivity analysis method that can more efficiently calculate the modal sensitivity of the large structures with thousands of degrees of freedom. This new sensitivity analysis technique integrates Sherman-Morrison-Woodbury formula, subspace iteration and forward-difference to achieve the goal of fast calculation. The innovations of the proposed method mainly include the following aspects. Firstly, the Sherman-Morrison-Woodbury formula is used to quickly calculate the perturbed flexibility matrix due to the minor modification in the structure. Then, the perturbed flexibility matrix is introduced into the subspace iteration method to calculate the perturbed modal parameters. Finally, the forward-difference algorithm is used to calculate the modal sensitivity. Two numerical examples are used to verify the superiority of the proposed modal sensitivity algorithm. Taking the 1952-bar structure as an example, the calculation time of the proposed algorithm is only 8.3 % and 18.2 % of that of the existing approximate modal superposition method and the improved Nelson’s method, respectively. In terms of calculation accuracy, the results obtained by the proposed method are exactly the same as the exact solution when the perturbation scale is set to 10−5. It is found that the proposed method significantly reduces computation time compared to the existing methods on the premise that the calculation accuracy is basically unchanged.