飞机结构件三维模型工艺性优化技术研究

针对MBD技术在航空制造企业产品研发当中的应用,研究了基于知识库的产品三维模型工艺性优化技术。通过对飞机结构件的可制造性分析,总结其工艺性优化内容。提出了"模型信息提取与简析—知识库建立—知识推理—优化结果可视化"模式的零件三维模型工艺性优化流程。综合运用多种知识与推理机制,建立模型特征与制造资源、工艺知识的关联,并对知识库结构以及推理过程进行了描述。解决了并行工程中的工艺性问题。开发的工艺性优化系统验证了该方法的可行性。

篦冷机工艺性能优化

系统研究了如何追求篦冷机最佳的热效率、尽量降低出篦冷机熟料温度、提高二次风温度,从篦冷机供风平衡、风机风压、篦板密封优化等方面做出详细分析。

浅论机床结构件的精细化设计

机床产品设计过程当中最重要的组成部分是结构件设计,结构件设计涵盖了多功能零部件的轻量化设计、材料设计、尺寸设计,以及优化改进。因此机床结构件设计是应当受到工程师的高度关注。而对于机床结构设计的相关专业性指标来说,其包含了机械设计、工艺设计等多元化组成部分。可以说现如今数控机床结构件设计,对整体产品的使用性能、用户的最终应用体验感会有直接的影响,为此必须要高度关注机床结构件的精细化设计。要遵循着设计目标,以及轻量化、短路程、优化配置的原则开展一系列的结构设计改进,并且探索更加优良的优化设计方法,这样才能够保障机床结构件精细化设计,在提升产品性能基础之上实现成本的有效节约。而本文则在此方面进行了论述与分析,希望本文的论述能够为新时期我国机床产品结构设计质量有效提升,提供一些帮助。

Microstructure evolution of modified die-cast AlSi10MnMg alloy during solution treatment and its effect on mechanical properties

To optimize the solution treatment process of a modified high-pressure die-cast AlSi10MnMg alloy, the influence of the solution treatment on the microstructure, mechanical properties and fracture mechanisms was studied using OM, SEM, EBSD and tensile test. The experimental results suggest that the solution treatment could be completed in a shorter time at a temperature much lower than the conventional practice. Surface blistering could be avoided and substantial strengthening effect could be achieved in the following aging process. Prolonging solution treatment time and elevating solution temperature would be meaningless or even harmful. The rapid evolution of eutectic silicon during solution treatment, especially at the early stage, affected the way of interaction among α-Al grains during plastic deformation, and changed the ultimate mechanical properties and fracture mode.

Effect of Zr content on crack formation and mechanical properties of IN738LC processed by selective laser melting

Two batches of commercial IN738LC alloy powders with different Zr contents were printed under the same parameters.The influences of Zr content(0.024 wt.% and 0.12 wt.%,respectively) in powders on crack density,distribution,formation mechanism and mechanical properties of selective laser melting(SLM)-treated parts were systematically studied.It was found that the crack density(area ratio) increases from 0.15% to 0.87% in the XOY plane and from 0.21% to 1.81% in the XOZ plane along with the Zr content increase from 0.024 wt.% to 0.12 wt.% in the original powders.Solidification cracks are formed along the epitaxially grown <001>-oriented columnar grain boundaries in molten pool center.The ultimate tensile strength of Sample 1(0.024 wt.% Zr) is 1113 MPa,and there are dimples in tensile fracture.With an increase in the Zr content to 0.12 wt.%(Sample 2),the ultimate tensile strength of Sample 2 decreases to 610 MPa,and there are numerous original cracks and exposed columnar grain boundaries in tensile fracture.The optimization of printing parameters of Sample 2 considerably increases the ultimate tensile strength by 55.2% to 947 MPa,and the plasticity is greatly improved.

Prediction of Cracking Gas Compressor Performance and Its Application in Process Optimization

Cracking gas compressor is usually a centrifugal compressor. The information on the performance of a centrifugal compressor under all conditions is not available, which restricts the operation optimization for compressor. To solve this problem, two back propagation (BP) neural networks were introduced to model the performance of a compressor by using the data provided by manufacturer. The input data of the model under other conditions should be corrected according to the similarity theory. The method was used to optimize the system of a cracking gas compressor by embedding the compressor performance model into the ASPEN PLUS model of compressor. The result shows that it is an effective method to optimize the compressor system.

Study of M-ZSM-5 nanocatalysts(M: Cu, Mn, Fe, Co …) for selective catalytic reduction of NO with NH_3: Process optimization by Taguchi method

A series of different transition metals(V,Co,Cr,Mn,Fe,Ni,Cu and Zn) promoted H-ZSM-5 catalysts were prepared by impregnation method and characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM) and transmission electron microscopy(TEM).The catalytic activity of these catalysts was evaluated for the selective catalytic reduction(SCR) of NO with NH_3 as reductant in the presence of oxygen.The results revealed that the catalytic activity of Cu-ZSM-5 nanocatalyst for NO conversion to N_2 was 80%at 300 ℃,which was the best among various promoted metals.Design of experiments(DOEs) with Taguchi method was employed to optimize NH_3-SCR process parameters such as NH_3/NO ratio,O_2 concentration,and gas hourly space velocity(GHSV) over Cu-ZSM-5 nanocatalyst at 250 and 300 ℃.Results showed that the most important parameter in NH_3-SCR of NO is O_2 concentration;followed by NH_3/NO ratio and GHSV has little importance.The NO conversion to N_2 of 63.1%and 94.86%was observed at 250℃ and 300℃,respectively under the obtained optimum conditions.

Regeneration of waste activated carbon after extracting gold with steam under microwave heating:Optimization using response surface methodology

The technology that waste activated carbon after extracting gold is regenerated with steam under microwave heating was studied. The influence of the activation temperature, activation duration and steam flow rate on iodine adsorption value and regeneration yield of activated carbon was investigated. The response surface methodology （RSM） technique was utilized to optimize the process conditions. The optimum conditions for the preparation of activated carbon are identified to be activation temperature of 831 ℃, activation duration of 40 min and steam flow rate of 2.67 mL/min. The optimum conditions result in an activated carbon with an iodine number of 1048 mg/g and a yield of 40%, and the BET surface area evaluated using nitrogen adsorption isotherm is 1493 m2/g, with total pore volume of 1.242 cm3/g. And the pore structure of activated carbon regenerated is mainly composed of micropores and a small amount of mesopores.

Processing maps and hot working mechanisms of supercritical martensitic stainless steel

The hot working mechanism of 2Cr11 MolVNbN steel was investigated by means of compression tests at temperatures of900-1150 ℃ and strain rates of 0.005-5 s^(-1).At strains of 0.2,0.3,0.5 and 0.7,the relationship among strain rate sensitivity,power dissipation efficiency and instability parameter under different conditions were studied.Power dissipation maps and instability maps at different strains were established.The optimal and the instable deformation regimes were established by the processing maps based on the dynamic material model.The processing maps were developed for the typical strains of 0.2,0.3,0.5 and 0.7,predicting the instability regions occurring at high strain rate more than 0.05 s^(-1),which should be avoided during hot deformation.The optimized processing parameters for hot working of 2CrllMolVNbN supercritical stainless steel were temperatures of 1080-1120 ℃ and strain rates of 0.005-0.01 s^(-1).

Development of an Emulator for the Plasma Process Control

This work aims at developing an automatic system for the control of the APS （air plasma spraying） plasma process in which some instability phenomena are present. APS is a versatile technique to produce coatings of powder material at high deposition rates. Using this technique, powder particles are injected into a plasma jet, where they are melted and accelerated towards a substrate. The coating microstructures and properties depend strongly on the characteristics of the plasma jet, which can be controlled by the adjustment of the process parameters. However, the imeractions among the spray variables, render optimization and control of this process are quite complex. Understanding relationships between coating properties and process parameters is mandatory to optimize the process technique and the product quality. We are interested in this work to build an on-line control model for the APS process based on the elements of artificial intelligence and to build an emulator that replicates the dynamic behavior of the process as closely as possible.

Fabrication of compact and stable perovskite films with optimized precursor composition in the fast-growing procedure

The fast-growing procedure （FGP） provides a simple, high-yield and lead （Pb）-release free method to prepare perovskite films. In the FGP, the ultra-dilute per- ovskite precursor solution is drop-cast onto a hot （-240℃） substrate where a perovskite film grows immediately ac- companied by the rapid evaporation of the host solvent. In this process, all the raw materials in the precursor solution are deposited into the final perovskite film. The potential pollution caused by Pb can be significantly reduced. Proper- ties of the FGP-processed perovskite films can be modulated by the precursor composition. While CH3NH3CI （MACI） affects the crystallization process and leads to full surface coverage, CH（NHz）2I （FAI） enhances the thermal stability of the film. Based on the optimized precursor composition of PbI2.（1-x）FAI.xMACI, x=0.75, FGP-processed planar het- erojunction perovskite solar cells exhibit power conversion efficiencies （PCEs） exceeding 15% with suppressed hysteresis and excellent reproducibility.