Optimal design of butterfly-shaped linear ultrasonic motor using finite element method and response surface methodology

A new method for optimizing a butterfly-shaped linear ultrasonic motor was proposed to maximize its mechanical output. The finite element analysis technology and response surface methodology were combined together to realize the optimal design of the butterfly-shaped linear ultrasonic motor. First, the operation principle of the motor was introduced. Second, the finite element parameterized model of the stator of the motor was built using ANSYS parametric design language and some structure parameters of the stator were selected as design variables. Third, the sample points were selected in design variable space using latin hypercube Design. Through modal analysis and harmonic response analysis of the stator based on these sample points, the target responses were obtained. These sample points and response values were combined together to build a response surface model. Finally, the simplex method was used to find the optimal solution. The experimental results showed that many aspects of the design requirements of the butterfly-shaped linear ultrasonic motor have been fulfilled. The prototype motor fabricated based on the optimal design result exhibited considerably high dynamic performance, such as no-load speed of 873 ram/s, maximal thrust of 27.5 N, maximal efficiency of 43%, and thrust-weight ratio of 45.8.

Finite Element Analysis and Optimal Design Based on ANSYS in a XH2408 Gantry Style NC Machining Center

ANSYS, the software of construction analysis, is used to analyze static and dynamic performances of a XH2408 gantry style numerical control （NC） milling machining center and optimize its construction using the finite element method. First, a finite element model is established and the static and dynamic analysis are completed as constraints and loads applied on the finite element model. It is found that both spindle box and gantry are the worst components of assembly in performance. Secondly, the spindle box and gantry are chosen as objects of optimal design separately, aiming to improve their performance. The optimal plans are accomplished on the basis of the minimum volume for the spindle box and the maximum inherent frequency for the gantry subject to the constrains. Finally, the machine tool improved is analyzed statically and dynamically based on the optimal results of the spindle box and gantry. The results show that optimal design with the finite element method increases static and dynamical performances of the XH2408 gantry style numerical control milling machining center and the technique is effective and practical in engineering applications.

OPTIMAL DESIGN PROCEDURE BASED ON VISCOPLASTIC MATERIAL BEHAVIOUR

The optimization problems belong to the family of the most important engineering problems. The objective of this paper is to proposed a very efficient numerical algo- rithm which is involved in an optimal design procedure in the field of viscoplasticity phenomena. Because of the complexity of design procedure, particularly in the field of viscoplas- ticity, the finite element method is used. This method provides a good structural discretization and very efficient mathematical describing of time-rate effects. Accord- ing to the design specifications, which will dictate a limiting design strain, using the proposed algorithm, the design life of the considered structure will be covered. For the justification of the proposed method an example is presented. On the basis of specifications data and environment conditions, an operating pressure of a pressure vessel is obtained.

AN ITERATIVE ALGORITHM FOR OPTIMAL DESIGN OF NON-FREQUENCY-SELECTIVE FIR DIGITAL FILTERS

This paper proposes a novel iterative algorithm for optimal design of non-frequency-selective Finite Impulse Response(FIR) digital filters based on the windowing method.Different from the traditional optimization concept of adjusting the window or the filter order in the windowing design of an FIR digital filter,the key idea of the algorithm is minimizing the approximation error by succes-sively modifying the design result through an iterative procedure under the condition of a fixed window length.In the iterative procedure,the known deviation of the designed frequency response in each iteration from the ideal frequency response is used as a reference for the next iteration.Because the approximation error can be specified variably,the algorithm is applicable for the design of FIR digital filters with different technical requirements in the frequency domain.A design example is employed to illustrate the efficiency of the algorithm.

Optimal design of V-type ultrasonic motor

V-type ultrasonic linear motor fabricated using a simple punching technique was proposed to utilize as an actuator of small precision machine.The stator of the motor is composed of a thin elastic body and four ceramics attached to the upper and bottom areas of the body.The ceramics have each direction of polarization.When two harmonic voltages with a 90° phase difference are applied to the ceramics,symmetric and anti-symmetric displacements will generate at the tip to produce an elliptical motion.A finite element analysis(ATILA) was conducted to simulate the motion pattern for the contact tip of the stator.To develop a model that generates the maximum displacement at contact tip,the FEM program was used for various lengths.In addition,an optimal model was chosen by considering the magnitude and shape of the displacement according to changes in frequency.The maximum elliptical displacement is shown by W2L11 model,which has a ratio of ceramic width to length of 1:5.5.However,the displacement of the contact tip is reduced by the bucking phenomenon if the ratio is larger than 1:6.

Study on optimal design to improve auto-body structural crashworthiness

In this paper the optimal model of the main energy absorbed structure in an auto-body “front rail”, based on structural crashworthiness is built. For an optimal design on structure crashworthiness, the new method is based on a response surface model and Pareto GA, which improves the efficiency and flexibility of an optimal design, that is brought forward. The traditional optimal method can not be applied in the design of an impact structure due to the high nonlinearity and large time cost of crashworthiness FE analysis. So the method of an optimal design based on crashworthiness is brought forward. After constructing the response surface model of auto-body crashworthiness, the Pareto GA can be applied to find the multi-objective globally. The optimal solution set can then be used to provide many scheme combinations for choice structural parameters.To acquire the optimized structure parameters on front rail crashworthiness, this simplified model of an original design is built. After studying various ways of reinforcing the cross-section to control the structural failure mode, a better method has been found. On the precondition of not increasing the mass of the structure, an optimal design of the front rail is performed further. Finally, the optimized scheme is implemented in the full-car impact analysis and crashworthiness is studied. With proper measures to control deformation of the front rail structure the crashworthiness can be improved with minor structural modifications.

SHAPE OPTIMIZATION DESIGN OF CRUSH TOOTH USING FINITE ELEMENT METHOD

The load condition of the mineral sizer is discussed. Acoording to three typical load cases presented, FEM and optimization models are established. Computed the model problems by use of ANSYS software and sequential unconstrained minimization technique, the stress distribution on c rush tooth and it's optimal shape are aquired. After analyzing the results, the relation between stress distribution and structural parameters is presented.

ADAPTIVE FINITE ELEMENT METHOD BASED ON OPTIMAL ERROR ESTIMATES FOR LINEAR ELLIPTIC PROBLEMS ON CONCAVE CORNER DOMAINS

An adaptive finite element procedure designed for specific computational goals is presented,using mesh refinement strategies based on optimal or nearly optimal a priori error estimates for the finite element method and using estimators of the local regularity of the unknown exact solution derived from computed approximate solutions.The proposed procedure is analyzed in detail for a non-trivial class of corner problems and shown to be efficient in the sense that the method can generate the correct type of refinements and lead to the desired control under consideration.

Optimal Design of Bobbinless Rotary Magnetorheological Material Based Brake

The paper presents a novel configuration in order to improve the compactness and manufacturing cost of magneto-rheological material(or fluid)based brakes(MRB in short).In conventional configurations of MRBs,the coil is normally wound on a nonmagnetic bobbin which is placed on the housing.This causes difficulties in manufacturing of the brake and the bottle-neck problem of magnetic circuit.In the proposed configuration,the coil is wound directly on the inner cylinder of the housing.In this case,the inner cylinder of the housing should be designed in a special shape that maximizes the magnetic flux across the MR fluid(MRF)duct.After proposing of the new configuration of the MRBs,the modeling of the MRBs is performed based on Bingham rheological model of the MRF.An optimal design of the proposed MRBs and conventional MRBs is then performed based on finite element analysis results of magnetic circuit of the MRBs.A comparative work between the optimal parameters of the proposed MRBs and conventional MRBs is conducted and the advanced performance characteristics of the proposed MRBs are investigated.

Shape Optimal Design of Hydrodynamic Bearing Based on Dynamic Characteristics

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Diamond Rib: A Mechanical Design Method for Improving the Stiffness of a Structure

It is necessary to decrease the weight of space satellites, while maintaining their stiffness. To achieve this weight reduction, many structures, such as honeycomb and isogrid, have been reported in the literature. In this paper, the diamond rib method, a mechanical design method for improving the stiffness of structures, is introduced. By applying this method to a small space satellite, we propose a new structure called the “Diamond Rib Structure”. This structure significantly improves the ability to withstand the vibrational disturbances in a rocket fairing.

Web-Based Synthetic Optimization Design System of Micro-Components

In order to meet the requirement of network synthesis optimization design for a micro component, a three-level information frame and functional module based on web was proposed. Firstly, the finite element method （FEM） was used to analyze the dynamic property of coupled-energy-domain of virtual prototype instances and to obtain some optimal information data. Secondly, the rough set theory （RST） and the genetic algorithm （GA） were used to work out the reduction of attributes and the acquisition of principle of optimality and to confirm key variable and restriction condition in the synthesis optimization design. Finally, the regression analysis （RA） and GA were used to establish the synthesis optimization design model and carry on the optimization design. A corresponding prototype system was also developed and the synthesis optimization design of a thermal actuated micro-pump was carded out as a demonstration in this paper.

Dynamic analysis and optimization of car's body-in-white based on superelement approach

An approach based on the superelement theory is proposed, and it is applied to model the car's body-in-white as well as to dynamic simulation and optimization. This approach can improve the calculation speed and do the dynamic optimization among substructures respectively in the car's body design. To meet the car's design of harshness, a dynamic optimal design model, based on the mean square of vertical displacement response at two points of the car floor, is proposed. Satisfactory results are achieved.

不同结构参数对高速开关阀液压力的影响研究

因其具有价格低廉、抗污染性强等优点,高速开关阀已被广泛运用到各种车辆的制动系统中,其动态性能直接影响到车辆的制动效果,而阀芯所受的液压力是决定高速开关阀动态特性优劣的关键参数。针对不同参数对高速开关阀液压力的影响,以及实际工程中阀芯液压力难以测量的问题,采用计算流体动力学(CFD)对高速开关阀进行了数值模拟。首先,基于有限体积法(FVM),建立了不同开度、压差、温度、以及结构参数(阀座节流孔直径和锥角)的三维仿真模型;然后,对比不同网格数量的仿真结果,排除了网格数量对于仿真结果的影响,并详细分析了各参数对液压力的影响,得出了高速开关阀液压力与各参数之间的变化规律;最后,采用响应面分析结合遗传算法对开关阀的结构参数进行了优化。研究结果表明:随着阀芯开度的增加,节流区域发生了转变;较大的压差会导致液压力产生较大幅度的变化;相较于高温,低温对液压力有着更加显著的影响;对结构参数进行优化后,最小开度的液压力提高了49.2%,提高了阀控制稳定性,为高速开关阀线性控制设计提供了理论基础。

热循环条件下BGA叠层焊点可靠性研究及参数优化

构建叠层焊点最优结构参数,提高BGA叠层焊点热循环条件下的可靠性具有重要的意义。建立有限元模型,分析叠层焊点在热循环条件下应力应变,运用田口正交法和曲面响应法,将焊点的高度、直径、间距、阵列作为实验设计的变量,关键焊点最大等效塑性应变作为优化目标。结果表明:焊点阵列对优化目标的影响权重最大,优化后的BGA叠层焊点结构参数如下,田口正交法:单层焊点高度为0.38 mm,焊点间距为0.55 mm,焊点直径为0.44 mm,焊点阵列为8×8;曲面响应法:单层焊点高度为0.387 mm,焊点间距为0.573 mm,焊点直径为0.446 mm,焊点阵列为8×8。对优化前后的寿命进行预测,优化后的叠层焊点寿命约是优化前的3.75倍。

一种异形支架结构的多目标优化设计方法

以航空发动机润滑油箱在机匣上安装时所采用的成附件安装结构支架为典型代表,具有复杂结构形式的异形支架,要求具有相对较高的刚度和较轻的质量,为此,建立了综合正交试验方法、有限元分析方法和神经网络拟合方法相结合的一种结构动力学特性的优化设计方法,对于具有复杂结构形式的支架结构具有较高的优化设计效率。应用正交试验方法,在支架样件模型的设计变量的可行域内合理地选择零件的解集,使该解集能充分反映优化的目标变量与设计变量之间的关系;使用有限元参数化仿真方法,对选择出的样件模型进行参数化仿真计算,得到解集中每个样件模型对应的优化的目标变量值;基于神经网络拟合方法,基于参数化仿真得到的数据,构建出设计变量与优化目标变量之间的数学模型,并使用多目标优化算法NSGA-Ⅱ进行迭代求解,得到最终优化设计结果;优化样件与初始样件的固有频率相对变化率与仿真计算值基本一致,可以验证支架结构多目标优化设计方法的准确性和有效性。

基于拓扑优化的SPMT驮梁支架轻量化设计

为解决用于跨线桥拆除的自行式模块化运输车(Self-propelled Modular Transporter, SPMT)驮梁支架结构冗余、重量偏大、制造及安装复杂等问题,依托京哈高速公路跨线桥拆除工程,在“16根标准节段钢管立柱+32道联结系杆”驮梁支架初步设计方案的基础上,以体积最小化为优化目标,利用Abaqus软件的拓扑优化模块开展驮梁支架轻量化设计研究,并对轻量化驮梁支架与初步设计的应力、位移及稳定性进行对比分析。结果表明:优化后的驮梁支架体积减少19.8%,支架联结系杆减少至12道,钢管立柱节段数量简化为2节段,节段长度提升至4 m,构件组拼联结接头数量减少约2/3,总重量较初步设计降低1.44 t;在最不利荷载工况下,驮梁支架优化前、后应力变化较小,最大位移差值在2 mm以内,且满足临界荷载系数大于4的稳定性要求。工程实践证明,轻量化驮梁支架力学性能满足要求,虽然安全系数小幅降低,但结构安全性与优化前基本一致;轻量化驮梁支架在施工现场组拼工作量及组拼时间均有所减少,经济效益显著。

UHPC箱梁桥面体系主要设计参数优化及试验研究

为获取UHPC箱梁桥面体系主要设计参数的合理取值范围,以某单跨跨径102 m的UHPC简支箱梁桥为背景,通过单参数影响效应分析和ANSYS优化设计模块分析对桥面板厚度h 1、上弦板高度h 2、上弦板厚度b及上弦板间距L的合理取值进行优化设计,并对优化后的UHPC箱梁桥面体系开展1∶2缩尺模型试验和有限元模拟,最后对UHPC箱梁桥面体系抗裂性能参数(上弦板受拉钢筋直径和上弦板高度)进行分析。结果表明:h 1、h 2、b和L合理取值范围分别为UHPC单箱室顶板(不含翼缘)横向跨度的1/40~1/35、1/10~1/8、1/37~1/31和1/2.8~1/1.4,对于背景工程h 1、h 2、b应分别不小于14、55、15 cm,L应不大于4 m;ANSYS优化结果与力学特性指标优化结果参数取值较为接近,优化后背景工程全桥UHPC体积减少约11.0%;试验梁上弦板发生面内受弯破坏,为UHPC箱梁桥面体系最不利受力部件;试验梁开裂应力值是正常使用极限状态设计值的2.14倍,具有较高安全储备,优化方案能满足工程应用要求;增大上弦板受拉钢筋直径及上弦板高度整体上可有效提高UHPC箱梁桥面体系的抗裂性能。

一种艾灸装置的结构设计及支撑座的优化设计

为了提高艾灸的质量和效率,设计了一种艾灸装置,整个艾灸装置既能实现自动清灰,且艾灸温度能精准控制。为了艾灸装置的使用方便和成本低减,对艾灸装置的关键部件艾灸支撑座进行了优化设计,以艾灸支撑座的三个结构尺寸为设计变量,利用OSF方法选取了设计变量的试验点,建立了径向基神经网络代理模型,并检验了该模型的精度。以艾灸支撑座的质量和最大变形量为多目标优化函数,以最大变形量和最大应力为约束条件,利用多岛遗传算法得到Pareto最优解集。在保证艾灸支撑座力学性能不降低的前提下,质量减轻了15.01%。结果表明,该方法具有较高的精度和较强的工程实用性。

基于田口-灰色关联法的驱动桥壳多目标优化设计

针对传统方法对驱动桥壳进行结构设计时,产品存在部分性能冗余的问题,本文提出一种结合田口法和灰色关联法的驱动桥壳多目标优化设计方法。以驱动桥壳结构参数为设计变量,桥壳刚度、强度和动态性能为优化目标,采用田口法正交试验设计实验方案,利用有限元法进行驱动桥壳典型工况的仿真分析,在试验数据信噪比分析的基础上结合灰色关联法对驱动桥壳进行多目标优化,得到最优结构参数组合。研究结果表明,优化后驱动桥壳的上述优化目标性能得到提升,验证了联合优化方法的有效性。