Structural optimization of some space camera

Aiming at the lightweight design of a vehicle-mounted radar array structure, the static analysis and modal analysis of the design model were carried out by Ansys to obtain the deformation, stress distribution cloud diagram and the first 6 order natural frequencies and modes of vibration. The calculation results show that the safety factor of each part of the radar array structure is above 2 and the maximum deformation is less than 20mm after the main array plate weight is reduced by 8%. The overall stiffness and strength of the radar array structure are good, which can meet the design requirements.

Based on the principle of static and modal analysis, carry on the static and dynamic characteristics analysis to the spindle of CK61125 machine tool using the finite element method (FEM). Then, got the static stress and deformation cloud, solve the first six order natural frequency and mode shape of the structure, provides a reference of engineering design and application for the machine tool spindle.

The high-temperature superconducting magnet (HTS) is one of the core technologies of a superconducting maglev. The effects of multiphysics fields including electromagnetic, mechanical, and thermal should be taken into consideration in design. Traditional design methods rely on the initial configuration and the engineer's experience and only consider the design for the heat conduction performance or the structure strength, which often significantly increases the weight. To solve the above problems, based on COMSOL Multiphysics software, the mathematical model of topology optimization of the main support was established with electromagnetic force and thermal stress as the input loads. The objective functions were assigned to total strain energy and heat leakage, combined with stress value and volume fraction constraint conditions. The solid isotropic material with penalization (SIMP) method was used to carry out the topological analysis of multiphysics. Finally, the innovative structure of main support is obtained. Through finite element analysis of multiphysics fields, the heat leakage, the max Von-Mises stress, and weight were taken as evaluation indexes to compare the optimal structure performance. The results show that the method adopted in this paper can reduce the heat leakage by 61.7% while reducing the weight of the main support by 85%, and the max Von-Mises stress does not exceed the yield limit of the material. The work of this paper provides a theoretical foundation for the engineering design of the heat conduction structure of a HTS magnet.

It is crucial to investigate methods for improving the stiffness performance of machine tools according to their specific dynamic working conditions. This paper presents a complete computer-aided workflow for structural transient topology optimization (TO) design, which is applied to the structural design issue of the JH31-250 press machine (Zhejiang Weili Forging Machinery Co., Ltd., Shaoxing, China). The stiffness influenced by the shape of the press frame under long-term dynamic impact load is analyzed, and an optimal design for the frame structure of the press machine is explored. In order to reduce the iteration time of the dynamic analysis, we also proposed a way to simplify the physical structure of the machine tool into a thin-walled structure model with artificial pseudo-density and introduced the hybrid cellular automata (HCA) criterion to obtain the topological iteration direction. This simplified model can be transformed back into 3D solid design of the press. The maximum relative displacement of the worktable in this optimized press model is 0.4896 mm, which is reduced by 31.02% compared to the original press model, which shows that the transient dynamic stiffness of the press machine frame is improved. This work presents a topological optimization method and path, which can be used for the optimization of dynamic stiffness in forging machine tools, and proves the correctness and effectiveness of the design for the transient dynamic stiffness of the frame.

Topology optimization design of the main structure of 6-DOF manipulator based on the variable density method

In this work, we present an adaptive feature-driven topology optimization method with the adaptability realized by using the well-known SIMP method. The proposed new method inherits the merits of both the feature-driven approach and SIMP method, and optimized results with clear and smooth boundaries can therefore be obtained without initial layout dependence. Specifically, in the early stage of optimization design, engineer features (i.e. design primitives) are systematically introduced into the design domain according to the sensitivity analysis result of the SIMP method, in view of its high numerical stability and strong versatility; and in the final stage, the topology optimization is implemented based solely on the feature-driven method, so that the high-quality design result can be achieved with very few variables. The transition between the two methods is carried out automatically by a novel volume restriction scheme, in which the structural volume obtained by the SIMP approach is limited to the difference between the prescribed maximum volume and the features’ total volume. It should be noted that the number and volume of engineer features are quite small at first several iterations, hence the effective force transferring path could not be formed just by using these features. But benefiting from the proposed volume restriction scheme, the connection between the load application and the displacement constraint positions can always be guaranteed because the optimization design is dominated by the SIMP method at initial iterations. The superiority and universality are demonstrated by typical numerical examples including the topology optimization design of the stiffest structure and compliant mechanism.KeywordsFeature drivenSIMPTopology optimizationAdaptabilityVolume restriction

Most of the offshore wind turbines (OWT) recently installed in Europe, China and North America are in shallow water. However, unlocking the full potential of OWT lies in deeper waters. Jacket substructures have presented themselves as a reliable foundation concept for transitional water depth. This study focuses on the structural static and dynamic analysis of the traditional jacket substructures (with X and K bracing) and the recently patented three-legged twisted jackets (with a twisted angle of 30 and 60 degrees) for deployment in transitional water (beyond 60 m). To facilitate comparison, the dimensions of all the jackets remain the same, while, the geometric configurations are distinct. Static analysis was implemented to better understand the global load bearing behaviour of the jackets. First, the global displacement patterns at the tower top are compared. The individual reactions at mud-line were investigated, followed by the evaluation of the maximum von Mises stress. Subsequently, this research went on to investigate the effect of dynamic loading. In this dynamic analysis, three main critical points were considered, including the wave point (67 m), the platform and the tower top. A modal analysis was performed to compute the mode shapes and natural frequencies for all the jackets. The first five modes of all the jackets were also checked against the results available for the OC4 project. A similar analytical approach was adopted for the structural design of monopile or tripod foundations for offshore wind turbines. The results showed that in the static analysis both the traditional jackets and the twisted jackets were safe under the provided load combination. The twisted jacket proved to possess excellent structural behaviour compared to the traditional four-legged jackets, while maintaining the merits of lower material usage with fewer nodes. Analysing the von Mises stress revealed that the maximum stress occurred at the transition piece and close to the working platform. The modal analysis results of the jackets demonstrated that the twisted jackets (30 and 60 degrees) with the first natural frequency of 0.29 and 0.31 Hz fell under the soft-stiff design category whereas the traditional four-legged jackets were classified as stiff-stiff designs. The discovered structural performance of OWTs equipped with various jacket foundations contributes to the preliminary structural selection and optimal design of foundations of OWTs to be installed in transitional water.

This paper takes a helical gear shaft as research subject and discusses the main structural parameters to see how it would affect natural frequency sensitivity. The parametrical model of helical gear shaft is created by using software PROE3.0. The natural frequencies and vibration shapes are calculated by the modal analysis. The relationship between the structural parameters and the natural frequency sensitivity can be obtained by means of ANSYS. The result shows that the structural parameters can affect the natural frequency sensitivity. The variation in low order natural frequency is similar to that in high order natural frequency. The effect of module on the natural frequency sensitivity is more remarkable comparing with pressure angle, modification coefficient and helical angle. Selecting structural parameters reasonably may reduce vibration and noise of the helical gear shaft effectively.

According to the requirements of the aerospace industry for high strength, high stiffness, and lightweight structural parts, topology optimization has been proved to be an effective product design method. As one of the most conceptual and prospective structural optimization design methods, topology optimization intends to seek the optimal layout of materials in an allowed design region under a given load and boundary conditions. Thus, the object of study in the article is the method of topological optimization of aircraft structures. The goal of this article is to analyze the existing approaches, algorithms, as well as application of the method of topological optimization in the aerospace field in applied problems. The tasks are to describe the existing various approaches methods, features, and research directions of topological optimization as well as to study the possibility of application in the manufacturing process of composite structures. The following results were obtained. The optimization methods are briefly explained and compared, and the advantages and limitations of each approach are discussed. The various ways of simultaneous optimization of fiber orientation and structural topology were described and analyzed. The features of different methods of continuous fiber orientation optimization method were reviewed. The discrete fiber orientation optimization methods were represented. The possibility of multi-scale concurrent topological optimization was described. The combination of topology optimization and additive manufacturing was considered. Finally, the topology optimization of FRC structures which have been resolved in literature are reviewed and the potential research fields requiring more investigation are pointed out. Conclusions. In the article, a comprehensive review of the topology optimization design of FRC structures was presented. The promising way is to combine topology optimization with additive manufacturing techniques. However, these proposed methods may not suitable for other more complex problems, such as bucking stability and natural frequency. Hence, the topology optimization design of complex FRC components under complicated conditions is the main challenge in the future. This can be a new trend in the topology design of FRC structures.

To detect faint target stars of 22nd magnitude and above, an astronomical exploration project requires its space camera's readout noise to be less than 5e- with long-time working stability. Due to the limitation of satellite, the traditional CCD detector-based camera does not meet the requirements, including volume, weight, and power consumption. Thereby, a low-noise ultra-stable camera based on 9 K × 9 K large target surface CMOS is designed to meet the needs. For the first time, the low-noise ultra-stable camera based on CMOS detector will be applied to space astronomy projects, remote sensing imaging, resource survey, atmospheric and oceanic observation and other fields. In this paper, the design of the camera is introduced in detail, and the camera is tested for several rounds at -40 °C; it also undergoes further testing and data analysis. Tests proved super stability and that the readout noise is lower than 4.5e-. Dark current, nonlinearity and PTC indicators meet the requirements of the astronomical exploration project.

A novel compliant mechanism with three degree of freedom (DOF) is proposed, based on the method of Freedom and Constraint Topology (FACT). One movement and two rotations are obtained in Case 3, Type 2 freedom space. A redundant constraint is added to improve the symmetry. The finite element modal (FEM) is established and static force analysis is conducted. Results demonstrate that the compliant mechanism is decoupled. Modal analysis is carried out with the finite element method. And four orders natural frequency and main vibration mode are obtained.

In this study, the topology-optimized solid-lattice hybrid structures with variable-density or iso-density are proposed to achieve the structural lightweight and performance requirements. Based on solid isotropic material with penalty topology optimization method, novel optimized structures are designed, including pure solid structure, pure lattice structure, and solid-lattice hybrid structure with iso-density or variable-density. All experimental samples with few 3D-printing defects are fabricated by selective laser sintering additive manufacturing method. Both three-point bending test and finite element simulation are conducted to evaluate the mechanical behaviors, including force-displacement curves and failure modes. Results show that hybrid structure with variable-density lattice has the highest peak force, while the pure lattice fails at the largest displacement which presents high energy absorption. The stress concentrations at the topology-optimized solid region are significantly alleviated by the support of the distributed lattice. It is illustrated that the reasonable lattice distribution around the topology-optimized solid region to increase the structural efficiency is mainly responsible for the obvious improvements. Furthermore, the solid-lattice hybridization-based topology optimization method is applied to the automotive crash beams, and simulations are performed to verify the effectiveness of method. This method provides valuable guidance for lightweight design of high-performance complex structures.

In this chapter, a topology optimization algorithm based on the topological derivative concept combined with a level-set domain representation method is presented. The model problem is governed by the elasticity system into two spatial dimensions. The topological asymptotic expansion of a tracking-type shape functional, associated with the nucleation of a small circular inclusion endowed with different material property from the background, is rigorously derived. Finally, the obtained theoretical result is used as a steepest-descent direction in the optimization process, which is applied in the context of compliance structural topology optimization and topology design of compliant mechanisms.

A flexible assembly cell has been designed for precision microstructures. In this paper, the static analysis and dynamic characteristics of the assembly cell are analyzed respectively. Through the finite element static analysis and simulation, we optimized the assembly cell’s structure design. Through the modal analysis, the first six nature frequencies and nature mode shapes are obtained. The overall oscillation of the first two sections, shows that the asssembly cell has a better dynamic performance. Meanwhile a modal test on assembly cell structure was also conducted. The first-order natural frequency has been obtained. The critical rotating speed is much higher than the maximum speed of the motor in the assembly cell, and no resonance phenomenon can be generated. The simulative results are consistent with the experimental results, and the correctness and adaptability of the simulation method are verified, ensuring the accuracy and reliability of the assembly cell.

<p>This work presents a numerical and analytical vibrational and structural analysis of a wing model with morphing winglets. The methodology for this analysis is developed by the undergraduate thesis students in collaboration with the faculty at Toronto Metropolitan University (formerly known as Ryerson University) and performs a static structural and modal analysis for the developed wing with morphing winglet model. This report summarizes the modal and static structural analysis conducted on the model. The CAD model for the study was developed on Solidworks while the two analyses were conducted on Ansys. The wing model was developed with four winglet configurations with varying cant angles. Various winglet configurations were designed with variable cant to study the effect of morphing winglet on the structure’s modal analysis. During the structural test, it was observed that the model undergoes a deflection of 0.001 in under the prescribed loading conditions. The modal analysis was completed for the four configurations using similar boundary conditions as for the static structural analysis. The average frequency for the first mode shape for all the configurations were recorded to be 29 Hz.</p> <p>The results for the modal analysis conducted on Ansys were then verified using an analytical methodology. The equations for this method were developed by modelling the wing as a slender and straight wing with rigid root and no sweep back angles. The procedure for this accounted for the maximum speed of the wind tunnel at Toronto Metropolitan University. The frequency solution obtained from the analytical methodology was then compared to the frequency obtained from the modal analysis completed on Ansys. The frequency at flutter was calculated to be 30 Hz. This validates the assumptions and expectations made prior to both methods of analysis.</p> <p>The next step for this study would be to build the 3D model of the wing with morphing winglets and conduct a ground vibration testing and wind tunnel testing. The observations made during this study, specifically, the natural frequencies, damping, and mode shapes, can be further compared and validated through conducting the ground vibration testing and wind tunnel testing of these models. By comparing the results, it is possible to validate the numerical models and simulation techniques used for the modal analysis and improve the design of the wing with winglets.</p>