A Multilevel Hierarchical Parallel Algorithm for Large-Scale Finite Element Modal Analysis

The strict and high-standard requirements for the safety and stability ofmajor engineering systems make it a tough challenge for large-scale finite element modal analysis.At the same time,realizing the systematic analysis of the entire large structure of these engineering systems is extremely meaningful in practice.This article proposes a multilevel hierarchical parallel algorithm for large-scale finite element modal analysis to reduce the parallel computational efficiency loss when using heterogeneous multicore distributed storage computers in solving large-scale finite element modal analysis.Based on two-level partitioning and four-transformation strategies,the proposed algorithm not only improves the memory access rate through the sparsely distributed storage of a large amount of data but also reduces the solution time by reducing the scale of the generalized characteristic equation(GCEs).Moreover,a multilevel hierarchical parallelization approach is introduced during the computational procedure to enable the separation of the communication of inter-nodes,intra-nodes,heterogeneous core groups(HCGs),and inside HCGs through mapping computing tasks to various hardware layers.This method can efficiently achieve load balancing at different layers and significantly improve the communication rate through hierarchical communication.Therefore,it can enhance the efficiency of parallel computing of large-scale finite element modal analysis by fully exploiting the architecture characteristics of heterogeneous multicore clusters.Finally,typical numerical experiments were used to validate the correctness and efficiency of the proposedmethod.Then a parallel modal analysis example of the cross-river tunnel with over ten million degrees of freedom(DOFs)was performed,and ten-thousand core processors were applied to verify the feasibility of the algorithm.

THE DESIGN AND ANALYSIS OF VIBRATION STRUCTURE OF VERTICAL DYNAMIC BALANCING MACHINE

A new type of vibration structure (i.e. supporting system, called swing frame cus- tomarily) of vertical dynamic balancing machine has been designed, which is based on an analysis for the swing frame of a traditional double-plane vertical dynamic balancing machine. The static unbalance and couple unbalance can be e?ectively separated by using the new dynamic balancing machine with the new swing frame. By building the dynamics model, the advantages of the new structure are discussed in detail. The modal and harmonic response are analyzed by using the ANSYS7.0. By comparing the ?nite element modal analysis with the experimental modal analy- sis, the natural frequencies and vibration modes are found. There are many spring boards in the new swing frame. Their sti?nesses are di?erent and assorted with each other. Furthermore, there are three sensors on the measuring points. Therefore, the new dynamic balancing machine can measure static unbalance and coupling unbalance directly, and the interaction between them is faint. The result shows that the new vertical dynamic balancing machine is suitable for inertial measurement of ?ying objects, and can overcome the shortcomings of traditional double-plane vertical dynamic balancing machines, which the e?ect of plane-separation is inferior. The vertical dynamic balancing machine with the new vibration structure can ?nd wide application in the future. The modelling and analysis of the new vibration structure will provide theoretical basis and practical experience for designing new-type vertical dynamic balancing machines.

Towards a hybrid model-driven platform based on flux balance analysis and a machine learning pipeline for biosystem design

Metabolic modeling and machine learning(ML)are crucial components of the evolving next-generation tools in systems and synthetic biology,aiming to unravel the intricate relationship between genotype,phenotype,and the environment.Nonetheless,the comprehensive exploration of integrating these two frameworks,and fully harnessing the potential of fluxomic data,remains an unexplored territory.In this study,we present,rigorously evaluate,and compare ML-based techniques for data integration.The hybrid model revealed that the overexpression of six target genes and the knockout of seven target genes contribute to enhanced ethanol production.Specifically,we investigated the influence of succinate dehydrogenase(SDH)on ethanol biosynthesis in Saccharomyces cerevisiae through shake flask experiments.The findings indicate a noticeable increase in ethanol yield,ranging from 6%to 10%,in SDH subunit gene knockout strains compared to the wild-type strain.Moreover,in pursuit of a high-yielding strain for ethanol production,dual-gene deletion experiments were conducted targeting glycerol-3-phosphate dehydrogenase(GPD)and SDH.The results unequivocally demonstrate significant enhancements in ethanol production for the engineered strains Δsdh4Δgpd1,Δsdh5Δgpd1,Δsdh6Δgpd1,Δsdh4Δgpd2,Δsdh5Δgpd2,and Δsdh6Δgpd2,with improvements of 21.6%,27.9%,and 22.7%,respectively.Overall,the results highlighted that integrating mechanistic flux features substantially improves the prediction of gene knockout strains not accounted for in metabolic reconstructions.In addition,the finding in this study delivers valuable tools for comprehending and manipulating intricate phenotypes,thereby enhancing prediction accuracy and facilitating deeper insights into mechanistic aspects within the field of synthetic biology.

NEW TYPE OF VIBRATION STRUCTURE OF VERTICAL DYNAMIC BALANCING MACHINE

A new type of vibration structure of vertical dynamic balancing machine isdesigned, which is based on the analysis for swing frame of a traditional vertical dynamic balancingmachine. The static unbalance and couple unbalance can be separated effectively by using the newmachine with the new swing frame. By building the dynamics model, the advantages of the newstructure are discussed in detail. The modal and harmonic response are analyzed by using theANSYS7.0. By comparing the finite element modal analysis with the experimental modal analysis, thenatural frequencies and vibration modes are found out. There are many spring boards in the new swingframe. Their stiffness is different and assort with each other. Furthermore, there are threesensors on the measurement points. Therefore, the new dynamic balancing machine can measure thestatic unbalance and couple unbalance directly, and the influence between them is faint. The newstructure has the function of belt-strain compensation to improve the measurement precision. Thepractical result indicates that the new vertical dynamic balancing machine is suitable for inertialmeasurement of flying objects, and can overcome the shortcomings of traditional double-planevertical dynamic balancing machines. The vertical dynamic balancing machine with the new vibrationstructure can be widely used in the future applications. The modeling and analysis of the newvibration structure provide theoretic instruction and practical experience for designing new type ofvertical dynamic balancing machines. Based on the design principles such as stiffness-matching,frequency-adjacence and strain-compensation and so on, various new type of vibration structures canbe designed.

高速线材吐丝头结构仿真与优化设计研究

针对高速线材轧制生产中吐丝机普遍存在振动值较大、连续运转稳定性较低、吐丝圈形不稳定等问题,对吐丝机关键部件吐丝头进行仿真优化研究。采用模态分析动力学控制方程、动平衡计算方程等,建立几何模型、有限元模型、运动学模型等并进行临界转速分析、模态分析和动平衡仿真分析,掌握吐丝头振动值较大的主要原因。为在设计阶段尽可能消除吐丝头的动平衡量,利用有限元仿真软件对原吐丝头进行模态分析,获得原吐丝头的第1阶临界转速为72.2 r/s,高于最高转速40 r/s,可按刚性转子对吐丝头进行动平衡。利用动力学仿真软件建立吐丝头的虚拟样机,对其进行双面动平衡仿真分析,获得吐丝头在两个校正面上所需的校正质量,并根据安装位置设计配重结构。通过对吐丝头进行动平衡优化,吐丝头在两个校正面的动不平衡质量分别由优化前的8.199 1 kg、6.655 4 kg下降为4.843 9×10^(-4) kg、3.603 8×10^(-4) kg,且1阶临界转速由72.2 r/s提升为72.75 r/s,满足设计要求。最后,将优化后的吐丝头安装在吐丝机空心轴上进行现场在线动平衡测试实验,吐丝头在线动平衡初始不平衡量为27.4 g,相位为232°,两个轴承位置测点的水平振动幅值分别为1.02μm、6.63μm,均小于10μm,满足设计要求。

Precision Balance Method for Cupped Wave Gyro Based on Cup-bottom Trimming

The mechanical balance process is the key process to eliminate the quadrature error and improve the performance of the cupped wave gyro. The conventional mechanical balance method for cupped wave gyro based on cup-wall trimming requires high control accuracy of trimming quantity, which increases the production cost and decreases the fabrication efficiency in large extent. However, it is hard to reach the high balance accuracy with the natural frequency split of mHz grade by using the conventional method. In this paper, the lumped mass dynamic model of the cupped wave gyro is built by discretization method, and the effects of different position trimming on the natural frequency are analyzed. It is pointed out that trimming off a tiny quantity of material from cup-wall causes large variation of the natural frequency is the main reason for the low accuracy of the conventional mechanical balance method. Then, a precision balance method for cupped wave gyro based on cup-bottom trimming is presented and the entire procedures of this method are given. The static balance process and dynamic balance process of the precision balance method are simulated by the finite element software. The simulation result shows that the precision balance method based on cup-bottom trimming brings less additional natural frequency split in the static balance process, minimizes the natural frequency split to mHz grade and rectify the angle of mode offset to 0.1° grade in the dynamic balance process, furthermore, the method decreases the requirement for control accuracy of trimming quantity evidently. The research work provides references for structure optimization design and balance process plan of the cupped wave gyro.

Optimal Design of Novel Electromagnetic-Ring Active Balancing Actuator with Radial Excitation

Imbalance vibration is a typical failure mode of rotational machines and has significant negative effects on the efficiency,accuracy,and service life of equipment.To automatically reduce the imbalance vibration during the operational process,different types of active balancing actuators have been designed and widely applied in actual production.However,the existing electromagnetic-ring active balancing actuator is designed based on an axial excitation structure which can cause structural instability and has low electromagnetic driving efficiency.In this paper,a novel radial excitation structure and the working principle of an electromagnetic-ring active balancing actuator with a combined driving strategy are presented in detail.Then,based on a finite element model,the performance parameters of the actuator are analyzed,and reasonable design parameters are obtained.Self-locking torque measurements and comparative static and dynamic experiments are performed to validate the self-locking torque and driving efficiency of the actuator.The results indicate that this novel active balancing actuator has sufficient self-locking torque,achieves normal step rotation at 2000 r/min,and reduces the driving voltage by 12.5%.The proposed novel balancing actuator using radial excitation and a combination of permanent magnets and soft-iron blocks has improved electromagnetic efficiency and a more stable and compact structure.

基于机器学习的迭代式数据均衡分区算法研究

为了实现数据均衡分区,提出一种基于机器学习的迭代式数据均衡分区算法。利用中心数据仓库技术对数据进行集成,并同时完成数据清洗与消减工作,采用核主成分分析法对集成得到的数据进行特征提取。根据特征提取结果,运用机器学习中的决策树算法构建分类器模型,实现数据迭代式均衡分区。实验结果表明,所提算法的数据查全率高于90%,平均查准率在85%以上,均优于传统方法。

单侧主缆刚度损伤悬索桥的模态分析及1:1内共振

悬索桥缆索在长期服役状态下损伤很难避免,单侧主缆刚度损伤会使系统出现主梁竖弯与扭转自由度间的耦合,这可能会进一步对悬索桥的模态和大振幅下的非线性响应造成影响.为此,建立了考虑单侧主缆刚度受损的七自由度悬索桥横截面模型,模态分析发现单侧主缆刚度损伤会使得系统前两阶固有频率曲线由交叉变为跃迁,导致两个本身相互独立的模态发生耦合.以此为基础,考虑悬索桥主缆刚度有损伤和未损伤两种工况,运用拓展的增量谐波平衡法(EIHB)计算系统在内共振条件下的非线性振动.研究结果表明:单侧主缆刚度有损伤的悬索桥在外部简谐激励下发生1∶1内共振,系统能量表现出明显的转移现象;竖向和扭转简谐激励下,有损伤的悬索桥较未损伤工况响应幅值有所减小,但出现了两个共振响应峰值,对激励频率更为敏感.数值结果与利用Runge-Kutta法计算得到的结果吻合一致,验证了EIHB法的准确性.

结构模态多级分层并行计算方法

基于稀疏存储技术和传统并行模态综合法提出了一种有限元结构模态分析多级分层并行计算方法。该方法在两级分区4次变换策略的基础上不仅实现了大量数据的分布式稀疏存储,提高了数据的内存访问效率,而且实现了系统整体缩减后的广义特征方程规模的有效降低,大幅度减少了广义特征方程的求解时间。此外,它还利用计算任务和异构众核集群硬件体系结构映射实现了计算过程的多级并行,不仅有效改善了不同层级的负载均衡,而且通过通信分离有效提高了通信效率。因此,它能够充分利用异构众核分布式存储并行计算机的体系结构特点提升大规模有限元模态并行计算效率。数值算例表明,相比于传统的并行模态综合法,稀疏存储格式模态多级分层并行方法能够大幅度节省内存空间和提高计算效率。

复合地层中土压平衡盾构掘进参数变化规律分析

对于复杂地质条件下的盾构隧道,科学设置掘进参数对工程的安全与高效至关重要。为研究复合地层中盾构掘进参数的变化规律,依托青岛地铁4号线沙子口站—崂山六中站区间左线线路,对下穿河道段、均匀黏土段、上软下硬段3种不同地质环境下的掘进参数进行了统计分析。统计特征值计算及相关性分析结果表明:1)下穿河道段因其主要为粉质黏土夹粗砂,总推进力数值最低;2)均匀黏土段掘进的参数较为稳定,土压平均值最高,总推进力和掘进速度的相关性最强;3)在上软下硬段掘进的参数变化频率与幅度较大,掘进速度最慢。

应用模态分析及傅里叶变换的柔性转子无试重动平衡方法

针对旋转机械不平衡导致的振动问题,提出一种的柔性转子现场动平衡方法。其通过有限元理论建立转子系统动力学模型,并将系统运动微分方程按模态振型展开,利用FFT及IFFT变换,获取频域下不平衡载荷谱,最终识别转子不平衡状态。仿真和试验结果均表明,该方法仅需在低于临界转速的状态下采集振动响应数据,并且无需停机试重,就能准确识别转子不平衡状态,添加配重后可使转子各阶不平衡振动得到有效抑制。

全自动动平衡机关键技术研究

介绍了用于中小型电机转子动平衡的两工位全自动动平衡机的系统组成、工作过程及体系结构,提出了数字跟踪窄带滤波方法,其中心频率可根据转子的转速自适应调整,准确地跟踪不平衡信号的频率,并保证零相移,可有效地去除变频率结构噪声.全面考虑了去重质量分布及圆周槽对实际去除不平衡量的影响,建立了精确的R型铣削去重模型和智能规划系统.开发了基于PCI总线的两级测控系统,将系统的协调控制分为动作级和系统级协调.应用结果表明,上述方法极大地提高了全自动动平衡机的精度和可靠性.

基于模态振型分析的大型汽轮机低压转子高速动平衡方法

针对目前传统影响系数法难以平衡某些大型汽轮机低压转子的难题,提出一种基于模态振型分析的大型柔性转子高速动平衡方法。在分析汽轮机转子系统结构的基础上,综合考虑了动平衡机摆架轴承座的动力特性,采用基于有限元的转子轴承动力学分析商业软件DyRoBeS建立了转子-轴承-摆架系统模型,分析转子系统临界转速和振型,从而根据转子的模态振型,结合柔性转子影响系数平衡法要点,设计合理的平衡工艺,有针对性的选择平衡校正面和平衡转速点,采取逐阶次平衡的方法,实现这类大型特殊柔性转子的动平衡。最后以哈汽产的66万千瓦大型汽轮机低压转子高速动平衡试验为例,应用结果表明采用该方法能有效平衡大型柔性转子,且减少了起机次数,节省了平衡费用。

新型立式动平衡机的设计与分析

在分析传统的双面立式动平衡机的振动结构的基础上 ,设计了一种新的立式动平衡机的振动结构 (即摆架 ) ,采用新摆架结构的动平衡机可以实现静不平衡和偶不平衡的有效分离。文中详细分析了新摆架结构的特点 ,并在ANSYS7.0平台上对摆架进行了有限元模态分析和谐响应分析。由于新的摆架结构采用多块簧板 ,在多个部位刚度匹配 ,且采用多个传感器安装于测量点处 ,这样新的动平衡机可以直接测量静不平衡和偶不平衡 ,且相互影响极小。实践证明 :采用新摆架结构的动平衡机特别适合于飞行物体的惯性测量 ,且克服了传统的双面立式动平衡机长期以来平面分离不佳的缺点 ,具有很高的推广价值。

多功能固体有机肥撒施机拨料辊的设计及试验研究

拨爪式拨料辊是有机肥(包括厩肥)撒施机关键部件。为此,根据有机肥撒施机整机设计目标,对拨料辊进行了设计,并计算优化了拨爪式拨料辊拨爪的折弯角、排列间距及排列方式,得到最佳设计参数。通过ANSYS Workbench对拨料辊进行模态分析,结果表明:在正常工作下拨料辊不会发生共振,符合设计要求。对整机进行试验验证,有机肥抛撒幅宽为5m,抛撒均匀性横向变异系数为15.4%,纵向变异系数为8.9%,均满足设计的要求。

硬支撑轮胎动平衡机的振动特性研究

对硬支承轮胎动平衡机的主轴系统及其他主要机械结构的振动特性进行了详细的理论分析和计算,并使用Pro/E软件进行实体建模,借助有限元仿真软件对模型主轴-轴承-基础系统等结构进行模态分析。通过激振实验,获得了可靠准确的实验数据,实验数据与计算分析数据具有较好的一致性,证明了所采用模型的正确性和可靠性。综合计算和实验结果可得,皮带结构对机械系统的振动特性影响较大,应重点考虑。同时提出优化和改进建议,为提高平衡机的测量精度提供参考。

有限元技术在基于能量平衡的机床动态设计中的应用

结构动态系统的能量平衡是实现机床结构动态设计的依据之一。文中尝试将有限元技术应用于基于能量平衡的机床结构动态设计,在介绍结构动态系统能量分析方法的基础上,针对结构动态系统的有限元模型,提出定量描述结构动态特性优劣的方法,通过算例对悬臂梁结构的集中参数模型能量分析结果与有限元能量分析结果进行比较,并以有限元能量分析实现悬臂梁结构的改进。结果表明该结构动态设计技术具有明显的优越性,最后将该技术应用于某平面磨床结构的动态特性分析,找出该磨床结构的薄弱环节,对该磨床结构的优化设计起到指导作用。

ANSYS在压电天平设计中的应用

利用ANSYS力电耦合的有限元分析方法,对一台三分量压电天平的性能进行评估。主要进行了静力、模态和瞬态响应特性分析,静力分析的目的是获得天平输出与施加载荷之间的关系,评估压电天平各分量的主灵敏度系数和分量间干扰灵敏度系数;模态分析的主要目的是获得压电天平的各阶振动频率和振型,用于评估天平的频率响应特性;瞬态响应特性分析主要用于评估天平在瞬态载荷下的响应特性,评估加速度计惯性补偿的有效性。ANSYS分析结果表明:压电天平的各分量主灵敏度较高,具有较好的分量间抗干扰能力,设计的天平频响较高,加速度计实现了对天平输出信号中惯性振动信号的补偿,能够满足激波风洞测力试验的需求。天平校准和风洞试验结果表明:天平的实际性能与有限元评估结果一致。

工作研究应用于企业生产线优化再设计——案例研究

运用工作研究方法对GY公司核心产品生产线的生产流程进行优化和再设计。根据实地观察获得的数据,应用5W1H提问技术、工时测定和人机作业分析等方法分析生产瓶颈工序及其产生原因。提出通过消除瓶颈工序、减少总检工序工位和人员冗余等措施,对作业工位的工作任务进行了重新设计,增加了1台ATE测试机器和减少了1个作业员。优化设计后的结果显示,生产线平衡率提升了29.9%,每小时产能提升了132PCS,每件产品制造成本减少了0.227元RMB。