Topology Optimal Design of Material Microstructures Using Strain Energy-based Method

敏感分析和使用的微观结构的拓扑学优化拉紧基于精力的方法被介绍。与 homogenization 方法相比，基于精力的方法有的紧张更高计算效率和简化编程有利。双凸的编程方法和周界限制计划被用来优化 2D 和 3D 微观结构。数字结果显示基于精力的方法有的紧张象为 orthotropic 材料的 homogenization 方法的一样的有效性。

Reversing design methodology of investment casting die profile based on ProCAST

Turbine blade is one of the critical components of aircraft engine.The performance of the engine depends on the shape and dimensions of components,but superalloy blade material cannot be easily machined.Although investment casting is an ideal process for such net-shape components,it requires an accurate determination of the casting-die profile.In this paper,a reversing design methodology for investment casting die using ProCAST is proposed.By combining the methods of simplifying grid files and quick sorting,the efficiency of sorting and matching can be largely improved.Further,the mould/die cavity anti-deformation system can be easily built.With ProCAST,the optimized die profile for investment casting can be established.

Research of Enterprise Resource Management Supporting Networked Manufacturing

The nature of networked manufacturing and agile manufacturing is to recognize enterprise resources timely and accurately. This paper mainly discusses an enterprise resource model method and the construction process. Furthermore, the system frameworks of software and application are put forward to realize various enterprise resources management based on a resource business process. Thus, we ensure the integration and sharing of enterprise resources for the requirement of networked manufacturing.

Raster to Vector Conversion for Engineering Drawings:Survey and Prospect

Recent development and recognition methods of raster to vector conversion for engineering drawings are presented. The advantages and disadvantages of all existing models are analyzed. Some research challenges and future directions are discussed.

Adaptive sliding mode control of the A-axis used for blisk manufacturing

As a key assembly in the 5-axis CNC machine tools, positioning precision of the A-axis directly affects the machining accuracy and surface quality of the parts. First of all, mechanical structure and control system of the A-axis are designed. Then, considering the influence of nonlinear friction, backlash, unmodeled dynamics, uncertain cutting force and other external disturbance on the control precision of the A-axis, an adaptive sliding mode control(ASMC) based on extended state observer(ESO) is proposed. ESO is employed to estimate the state variables of the unknown system and an adaptive law is adopted to compensate for the input dead-zone caused by friction,backlash and other nonlinear characteristics. Finally, stability of the closed-loop system is guaranteed by the Lyapunov theory. Positioning experiments illustrate the perfect estimation of ESO and the stronger anti-interference and robustness of ASMC, which can improve the control precision of the A-axis by about 40 times. Processing experiments show that the ASMC can reduce the waviness,average error and roughness of the processed surface by 35.63%, 31.31% and 30.35%, respectively.

Riveting Process Modeling and Simulating for Deformation Analysis of Aircraft＇s Thin-walled Sheet-metal Parts

固定关节是重要联合方法之一永久地系住二薄墙的表金属部分。高效地在飞机为表演，疲劳耐久性和固定结构的损坏分析并且估计固定关节的变丑是很基本的。这篇论文研究薄墙的表金属的分析变丑分开的精确地当模特儿并且模仿到更多的固定过程数学。首先，为铆钉的有弹性的变丑，塑料变丑和 springback 的数学和力学模型被力学理论造。根据 ABAQUS 系统，第二，一个有限元素系统，由铆钉组成的一个例子和铝合金的二薄墙的表金属部分被用来分析并且模仿压力和变丑。而且，比较在有限元素方法数学和力学模型和那些获得的结果之间被做(女性) 。模型被计算和例子的模拟结果证明真。

Stiffeners layout design of thin-walled structures with constraints on multi-fastener joint loads

The purpose of this paper is to present an extended topology optimization method for the stiffeners layout design of aircraft assembled structures. Multi-fastener joint loads and manufacturing constraints are considered simultaneously. On one hand, the joint loads are calculated and constrained within a limited value to avoid the failure of fasteners. On the other hand, the manufacturing constraints of the material distribution in the machining directions of stiffeners are implemented by an improved piecewise interpolation based on a beveled cut-surface. It is proven that the objective function is strictly continuous and differentiable with respect to the piecewise interpolation. The effects of the extended method with two different constraints are highlighted by typical numerical examples. Compared with the standard topology optimization, the final designs have clearly shown the layout of stiffeners and the joint loads have been perfectly constrained to a satisfying level.

Influence of TiB2 particles on machinability and machining parameter optimization of TiB2/Al MMCs

In situ formed TiB_2 particle reinforced aluminum matrix composites(TiB_2/Al MMCs)have some extraordinary properties which make them be a promising material for high performance aero-engine blade.Due to the influence of TiB_2 particles, the machinability is still a problem which restricts the application of TiB_2/Al MMCs.In order to meet the industrial requirements, the influence of TiB_2 particles on the machinability of TiB_2/Al MMCs was investigated experimentally.Moreover, the optimal machining conditions for this kind of MMCs were investigated in this study.The major conclusions are:(1) the machining force of TiB_2/Al MMCs is bigger than that of nonreinforced alloy and mainly controlled by feed rate;(2) the residual stress of TiB_2/Al MMCs is compressive while that of non-reinforced alloy is nearly neutral;(3) the surface roughness of TiB_2/Al MMCs is smaller than that of non-reinforced alloy under the same cutting speed, but reverse result was observed when the feed rate increased;(4) a multi-objective optimization model for surface roughness and material removal rate(MRR) was established, and a set of optimal parameter combinations of the machining was obtained.The results show a great difference from Si C particle reinforced MMCs and provide a useful guide for a better control of machining process of this material.

Dynamics modeling and pressure control of composites tape winding system based on LQSMC

Pressure fluctuations during the composite fiber winding process seriously affect the produces compactness strength,fatigue resistance,stress uniformity,and resin content.The accuracy of pressure control systems is affected by nonlinear disturbances,such as friction,parameter perturbation,and measurement noise.A robust control algorithm based on linear quadratic optimal control and sliding mode control(LQSMC)is proposed to overcome these problems.The method is based on the system state space expression and linear quadratic optimal control.The state space model of the system is improved by using a Kalman filter and control input for state estimation,and a new sliding surface equation is defined.The ameliorated control algorithm exhibits good performance and can effectively suppress sliding mode control(SMC)chattering.Simulation and experimental results show that LQSMC offers high control precision,much stronger antiinterference,and robustness,which can effectively improve the positioning and tracking accuracy of a pressure control system compared with linear quadratic optimal control(LQC).The winding pressure control precision is improved by 45%to 50%.The results show that the porosity of composite fiber tape winding products decreased thanks to our method.

Surface integrity and fatigue behavior when turning γ-TiAl alloy with optimized PVD-coated carbide inserts

This paper presents a comprehensive investigation on the effects of tool and turning parameters on surface integrity and fatigue behavior in turning c-Ti Al alloy. The wear of inserts surface, cutting forces, and surface roughness were studied to optimize PVD-coated carbide inserts.Surface topography, residual stresses, microhardness, and microstructure were analyzed to characterize the surfaces layer under different turning parameters. Surface integrity and fatigue life tests of c-Ti Al alloy were conducted under turning and turning-polishing processes. The results show that compared to CNMG120412-MF4, CNMG120408-SM is more suitable because it obtained low cutting force, surface roughness, and tool wear. With increasing the cutting speed and depth, the depths of the compressive residual stress layer, hardening layer, and plastic deformation layer increased. For turning and turning-polishing specimens, the compressive residual stress was relaxed by less than 20%–30% after 10~7 cycles. The fatigue life of a turning-polishing specimen with R_a= 0.15 mm has increased 3 times from that of a turning specimen with R_a= 0.43 mm.

Mechanistic identification of cutting force coefficients in bull-nose milling process

An improved method to determine cutting force coefficients for bull-nose cutters is proposed based on the semi-mechanistic cutting force model. Due to variations of cutting speed along the tool axis in bull-nose milling, they affect coefficients significantly and may bring remarkable discrepancies in the prediction of cutting forces. Firstly, the bull-nose cutter is regarded as a finite number of axial discs piled up along the tool axis, and the rigid cutting force model is exerted. Then through discretization along cutting edges, the cutting force related to each element is recalculated, which equals to differential force value between the current and previous elements. In addition, coefficient identification adopts the cubic polynomial fitting method with the slice elevation as its horizontal axis. By calculating relations of cutting speed and cutting depth, the influences of speed variations on cutting force can be derived. Thereby, several tests are conducted to calibrate the coefficients using the improved method, which are applied to later force predictions. Eventually, experimental evaluations are discussed to verify the effectiveness. Compared to the conventional method, the results are more accurate and show satisfactory consistency with the simulations. For further applications, the method is instructive to predict the cutting forces in bull-nose milling with lead or tilt angles and can be extended to the selection of cutting parameters.

Tool Path Generation for Clean-up Machining of Impeller by Point-searching Based Method

用机器制造大扫除区域的质量在 impeller 的表演上有强烈影响。以便很快计划大扫除工具路径并且获得好完成表面质量，一个有效、柔韧的工具路径产生方法被介绍，它采用一条途径基于寻找点。用机器制造的大扫除在这提到纸为有一个球结束切割器的一个自由形态的模型是铅笔切割和多层的切切割。为铅笔切割，切割器中心位置能经由判定它是否满足距离要求被决定。在寻找的方向和跟踪方向被决定了以后，由与两分的想法采用寻找点的算法，所有切割器接触(CC ) 指，切割器地点(CL ) 指能被发现，大扫除边界罐头也很快被定义。然后，工具路径被产生。基于铅笔切割的主要概念，一个多层的切切割方法被建议，它与它的半径利用一个球结束切割器不到大扫除的设计半径区域。使用中间的虚拟切割器的一个序列把大扫除区域划分成几层并且为最后的层给尖顶高度忍耐，然后，为所有层的工具路径被计算。最后，计算机实现也在这份报纸被介绍，并且结果证明建议方法是可行的。

Mtuli-objective Optimization Method for Automatic Drilling and Riveting Sequence Planning

There are numerous riveting points on the large-sized aircraft panel,irregular row of riveting points on delta wing.It is essential to plan the riveting sequence reasonably to improve the efficiency and accuracy of automatic drilling and riveting.Therefore,this article presents a new multi-objective optimization method based on ant colony optimization(ACO).Multi-objective optimization model of automatic drilling and riveting sequence planning is built by expressing the efficiency and accuracy of riveting as functions of the points' coordinates.In order to search the sequences efficiently and improve the quality of the sequences,a new local pheromone updating rule is applied when the ants search sequences.Pareto dominance is incorporated into the proposed ACO to find out the non-dominated sequences.This method is tested on a hyperbolicity panel model of ARJ21 and the result shows its feasibility and superiority compared with particle swarm optimization(PSO) and genetic algorithm(GA).

Comparisons of Heat Transfer Enhancement of an Internal Blade Tip with Metal or Insulating Pins

Cooling methods are needed for turbine blade tips to ensure a long durability and safe operation.A common way to cool a tip is to use serpentine passages with 180-deg turn under the blade tip-cap taking advantage of the threedimensional turning effect and impingement like flow.Improved internal convective cooling is therefore required to increase the blade tip lifetime.In the present study,augmented heat transfer of an internal blade tip with pin-fin arrays has been investigated numerically using a conjugate heat transfer method.The computational domain includes the fluid region and the solid pins as well as the tip regions.Turbulent convective heat transfer between the fluid and pins,and heat conduction within pins and tip are simultaneously computed.The main objective of the present study is to observe the effect of the pin material on heat transfer enhancement of the pin-finned tips.It is found that due to the combination of turning,impingement and pin-fin crossflow,the heat transfer coefficient of a pin-finned tip is a factor of 2.9 higher than that of a smooth tip at the cost of an increased pressure drop by less than 10%.The usage of metal pins can reduce the tip temperature effectively and thereby remove the heat load from the tip.Also,it is found that the tip heat transfer is enhanced even by using insulating pins having low thermal conductivity at low Reynolds numbers.The comparisons of overall performances are also included.