探究白车身轻量化的科学设计方法

随着科学技术的发展,人们在环境保护方面的意识不断提升,而汽车作为人出行过程中最为重要的工具之一,成为研究重点。由于汽车油耗与自身质量存在重要关联,基于此研究了科学性白车身轻量化设计方式,文章通过设计变量选择、试验设计以及构建与之相关的近似模型,得出优化方案。望本次研究能够帮助我国汽车工程得到进一步发展。

INTEGRATED DESIGN OF AN ELECTRIC POWERED UNMANNED AIR VEHICLE USING CONCURRENT SUBSPACE DESIGN

The concurrent subspace design (CSD) framework has been used to conduct a preliminary design optimization of an electric powered, unmanned air vehicle (EPUAV) operating at a low Reynolds number. A multidisciplinary system analysis that includes aerodynamics, weights, propulsion, performance and stability and control has been developed for this class of vehicles. The CSD framework employs artificial neural network based response surfaces to provide approximations to the design space. The EPUAV system includes 25 continuous and 4 discrete design variables. The CSD framework was able to identify feasible designs with significant weight reductions relative to any previously considered (i.e. initial database) designs. This was accomplished with a limited number of system analyses. The results also demonstrate the nature of this design framework adaptive to changes in design requirements.

EFFICIENT METHOD FOR MULTIDISCIPLINARY DESIGN OPTIMIZATION BY CONSIDERING UNCERTAINTY

A new reliability-based multidisciplinary design optimization （RBMDO） framework is proposed by combining the single-loop-based reliability analysis （SLBRA） method with multidisciplinary feasible （MDF） method. The Kriging approximate model with updating is introduced to reduce the computational cost of MDF caused by the complex structure. The computational efficiency is remarkably improved as the lack of iterative process during reliability analysis. Special attention is paid to a turbine blade design optimization by adopting the proposed method. Results show that the method is much more efficient than the commonly used double-loop based RBMDO method. It is feasible and efficient to apply the method to the engineering design.

Multidisciplinary design optimization on production scale of underground metal mine

In order to ensure overall optimization of the underground metal mine production scale, multidisciplinary design optimization model of production scale which covers the subsystem objective function of income of production, safety and environmental impact in the underground metal mine was established by using multidisciplinary design optimization method. The coupling effects from various disciplines were fully considered, and adaptive mutative scale chaos immunization optimization algorithm was adopted to solve multidisciplinary design optimization model of underground metal mine production scale. Practical results show that multidisciplinary design optimization on production scale of an underground lead and zinc mine reflect the actual operating conditions more realistically, the production scale is about 1.25 Mt/a (Lead and zinc metal content of 160 000 t/a), the economic life is approximately 14 a, corresponding coefficient of production profits can be increased to 15.13%, safety factor can be increased to 5.4% and environmental impact coefficient can be reduced by 9.52%.

Multidisciplinary design optimization for air-condition production system based on multi-agent technique

In order to guarantee the overall production performance of the multiple departments in an air-condition production industry, multidisciplinary design optimization model for production system is established based on the multi-agent technology. Local operation models for departments of plan, marketing, sales, purchasing, as well as production and warehouse are formulated into individual agents, and their respective local objectives are collectively formulated into a multi-objective optimization problem. Considering the coupling effects among the correlated agents, the optimization process is carried out based on self-adaptive chaos immune optimization algorithm with mutative scale. The numerical results indicate that the proposed multi-agent optimization model truly reflects the actual situations of the air-condition production system. The proposed multi-agent based multidisciplinary design optimization method can help companies enhance their income ratio and profit by about 33% and 36%, respectively, and reduce the total cost by about 1.8%.

Analyzing the Relation Between Earthquakes and Active Faults Based on the Parameter Optimization Model

The gestation and occurrence of strong earthquakes are closely related to fault activity, which is not only revealed by abundant experimentation and seismism but also proved by modern seismology. On the Chinese mainland, the relation between earthquake activity and active faults is one of the bases for partitioning potential seismic sources, analyzing the seismotectoulcs and estimating location of strong earthquakes.Due to the nonuniformity of earth media, instability of observation systems and disturbance of the environment, etc, the variety of observational data is complicated, that is, there is no absolutely ＂normal＂ or ＂abnormal＂, and seismic anomalies can be divided into many mutually exdusive＂ abnormal states＂. In different conditions of combined time-spacestrength, determining seismic anomalies by different monomial forecast methods and its efficiency could be different due to the uncertainty of a precursor itself or complexity of the relationship between a precursor and earthquake gestation. It is very difficult to discover and dispose of this difference in actual application in a ＂two-state＂ model. But in a ＂multi-state＂ model, the difference can be easily reflected and the optimal combination of forecasting parameters for a forecast method can also be determined easily. Based on the ＂multi-state＂ precursory model and the optimization method for parameters of earthquake forecast model under the condition of optimal forecast efficiency, the relationship of the spatial location of earthquake with M ≥ 6.0 and active faults in three seismic belts are analyzed. The results demonstrate that in the Hetao Seismic Belt, seismicity is mostly concentrated in the range of 20 km along the fault, the optimization model can forecast the location of potential earthquakes of M ≥ 6.0 near the faults with a relatively high accuracy and the reliability is 0.5 ; while in the Qilian Mt. Seismic Belt, the reliability only reaches 0.14 when we use the model to estimate earthquakes within 30 km range along the faults. The ＂multi-state＂ precursory model, the efficiency-evaluating model and the parameter selection of individual earthquake forecast model based on optimal efficiency are of certain revelatory and practicable meanings for developing knowledge about precursors, investigating the laws of earthquake preparation and searching for optimal forecasting methods.

An Approach towards the Incorporation of Soft Aspects Such as Manufacturing Efforts into Structural Design Optimization

This paper introduces an efficient holistic approach to the design optimization of lightweight structures of braided fiber-reinforced plastic material. The approach aims to mitigate the paradox of making design decisions at early development phases, when necessary information is incomplete or lacking detail so as to properly make these decisions. However, expert knowledge is available and though it is imprecise in nature, it can compensate to create useful models. Manufacturing effort for the braiding process has been described by information accumulated via interviews with braiding experts. This information is then modelled using the soft-computing approach by fuzzy-rule-based systems. The resulting models can further be efficiently integrated into the structural design optimization process. A multidisciplinary design optimization is facilitated considering several aspects including manufacturing effort and structural mechanics, which can be used in early design phases leading to more holistic designing and, thereby, unlocking lightweight and cost-reducing potentials. Benefits of this method, including viability and ease of implementation, are proven by investigations on two academic test problems before advancing to the challenging automotive engineering design problem of the roadster A-pillar.

An approach for shape optimization of stratosphere airships based on multidisciplinary design optimization

Airship shape is crucial to the design of stratosphere airships. In this paper, multidisciplinary design optimization (MDO) technology is introduced into the design of airship shape. We devise a composite objective function, based on this technology, which takes account of various factors which influence airship performance, including aerodynamics, structures, energy and weight to determine the optimal airship shape. A shape generation algorithm is proposed and appropriate mathematical models are constructed. Simulation results show that the optimized shape gives an improvement in the value of the composite objective function compared with a reference shape.

Efficient aero-structural design optimization: Coupling based on reverse iteration of structural model

Traditional coupled multi-disciplinary design optimization based on computational fluid dynamics/computational structure dynamics(CFD/CSD)aims to optimize the jig shape of aircraft,and general multi-disciplinary design optimization methodology is adopted.No special consideration is given to the aircraft itself during the optimization.The main drawback of these methodologies is the huge expanse and the low efficiency.To solve this problem,we put forward to optimize the cruise shape directly based on the fact that the cruise shape can be transformed into jig shape,and a methodology named reverse iteration of structural model(RISM)is proposed to get the aero-structural performance of cruise shape.The main advantage of RISM is that the efficiency can be improved by at least four times compared with loosely-coupled aeroelastic analysis and it maintains almost the same fidelity of loosely-coupled aeroelastic analysis.An optimization framework based on RISM is proposed.The aerodynamic and structural performances can be optimized simultaneously in this framework,so it may lead to the true optimal solution.The aerodynamic performance was predicted by N-S solver in this paper.Test shows that RISM predicts the aerodynamic and structural performances very well.A wing-body configuration was optimized by the proposed optimization framework.The drag and weight of the aircraft are decreased after optimization,which shows the effectiveness of the proposed framework.

Multidiscipline collaborative optimization of differential steering system of electric vehicle with motorized wheels

Based on the multidiscipline design optimization theory, a multidiscipline collaborative optimization model of the differential steering system of electric vehicle with motorized wheels is built, with the steering economy as the main system and the steering road feel, the steering flexibility and the mechanic character of the steering sensors as the subsystems. Considering the coupled relationship of each discipline, the main system is optimized by the multi-island algorithm and the subsystems are optimized by the sequential quadratic programming algorithm. The simulation results show that the steering economy can be optimized by the collaborative optimization, and that the system can get good steering road feel, good steering flexibility and good mechanic character of the steering sensors.

Study on Capital Supply Capacity of Forestry Scientific Innovation

Scientific innovation system is the backbone and engine of economic development and social progress as well as the foundation and backup of comprehensive national strengths and international competitiveness. Factors determining scientific innovation capacity mainly include the forming of an environment for innovation, the capital supply for innovation, innovation performances, innovation diffusivity, etc. The present paper is mainly studying on the capital supply for forestry scientific innovation and analyzing the capital supply capacity for forestry scientific innovation through the forming of scientific innovation capital, the effective supply of scientific innovation capital, the optimization mechanisms to promote the effective capital supply, etc.