Contribution to the Full 3D Finite Element Modelling of a Hybrid Stepping Motor with and without Current in the Coils

The paper presents our contribution to the full 3D finite element modelling of a hybrid stepping motor using COMSOL Multiphysics software. This type of four-phase motor has a permanent magnet interposed between the two identical and coaxial half stators. The calculation of the field with or without current in the windings (respectively with or without permanent magnet) is done using a mixed formulation with strong coupling. In addition, the local high saturation of the ferromagnetic material and the radial and axial components of the magnetic flux are taken into account. The results obtained make it possible to clearly observe, as a function of the intensity of the bus current or the remanent induction, the saturation zones, the lines, the orientations and the magnetic flux densities. 3D finite element modelling provide more accurate numerical data on the magnetic field through multiphysics analysis. This analysis considers the actual operating conditions and leads to the design of an optimized machine structure, with or without current in the windings and/or permanent magnet.

3D打印不同骨密度的椎间融合器优化设计

依据颈椎的原始数据,通过医学图像处理和逆向建模操作分别重建了颈椎C6段和C7段的模型,并将其装配形成颈椎C6~C7节段,得到椎间融合器基本数据。依据基本数据分别建立了矩形多孔、梯度多孔、八面体多孔椎间融合器模型。对融合器施加成年男性颈部所受到的最大力,通过有限元分析求解应力、应变以及最大变形量。计算设计的椎间融合器的弹性模量下降情况,对不同孔隙率的矩形多孔结构椎间融合器进行分析,并优化设计。结果可知,3种结构的融合器均有不同程度的弹性模量下降,而矩形结构椎间融合器的孔隙率在60%左右时,弹性模量下降得最多。

轻量化钵育秧盘的3D打印及有限元分析

新型插秧机的研发过程中,秧盘尺寸需要不断调整,为提高研发效率,引入3D打印技术制作秧盘。为使得秧盘更接近实际工况,对秧盘进行了抽壳处理以达到轻量化。为了保证秧盘组装后的强度,仅对秧盘3号块件进行抽壳。考虑到秧盘的尺寸大于3D打印机的最大打印尺寸,对秧盘进行了拆分和组装设计。为验证轻量化互锁拆分秧盘设计的合理性,对3种不同设计方式的秧盘进行了有限元分析。研究表明互锁拆分轻量化秧盘不仅能达到轻量化要求,而且其变形幅度也小。最后对轻量化互锁拆分秧盘进行了3D打印试制。实践结果表明,采用轻量化互锁设计后的秧盘,不仅省材、轻量,也能同时满足应用力学性能要求。

新型3D负泊松比多孔材料胞元的弹性性能研究

空间负泊松比多孔材料优异的多向能量吸收和体积变化可调特性,使其在航空航天和军工设备等领域具有广阔的应用前景。论文设计了一种正交各向同性的新型空间负泊松比多孔材料的胞元结构(REC胞元),并对其进行了增强设计。利用有限元仿真方法研究了胞元z向单轴压缩时的弹性力学行为,详细分析了几何参数对胞元无量纲弹性模量和泊松比的影响,并利用一组3D打印胞元试样的压缩试验对仿真结果进行了验证。所得结果可以为负泊松比多孔材料的功能设计和增强提供依据。

基于AE中Element 3D插件的三维特效制作思路与实例分析

AE中Element 3D是一款具有real time rendering(实时渲染)特性的插件,即在制作3D效果过程中可以直接在屏幕上看到渲染效果,CG运算的效率得以大幅提升,是AE中为数不多的支持完全3D渲染特性的插件之一。本文结合两个具有代表性的实例分析了该插件实现三维特效制作的方法。

基于细胞黏附的不同微结构3D打印多孔生物支架流体力学有限元分析

目的研究不同孔形态结构的3D打印支架应用于骨再生时对细胞黏附的影响。方法利用MSLattice软件设计四种具有不同孔形态的支架结构,分别是立方形(Cubic)、六边形(Hexagon)、钻石形(Diamond)和螺旋形(Gyroid)。利用有限元分析(Finite element method,FEM)和计算机流体建模(Computational fluid dynamics,CFD)的原理,使用Simenns Star CCM+软件对四种支架内部流体域进行组织液流动模拟,模拟细胞黏附过程,测量支架内组织液流速和压力、组织液的渗透率和黏附层厚度。结果当液体流经四种支架后,压力会被逐渐削弱,但由于支架相对规则,压力均呈现出梯度分布,组织液流经四种支架前的压力值模拟按顺序依次为:Gyroid>Cubic>Diamond>Hexagon。流速:Cubic>Gyroid>Diamond>Hexagon。四种支架的渗透率:Diamond>Hexagon>Cubic>Gyroid。黏附层厚度:Gyroid>Hexagon>Cubic>Diamond。结论流体力学分析结果显示,Gyroid支架具有更低的渗透率和最高的黏附层厚度,更有利于细胞黏附。

面向3D打印的排爆机械臂栅格优化

文中以排爆机器人机械臂为研究对象,设计了一种面向3D打印的排爆机械臂。通过SolidWorks建立机械臂三维模型,采用ANSYS Workbench对原始大臂进行静力学分析,再根据分析结果对机械臂大臂进行拓扑优化。在满足大臂工作要求的前提下,采用Altair Inspire为拓扑优化大臂分别填充3种不同直径的栅格结构。通过Inspire对优化后的大臂进行静力学分析,与原始大臂相比,优化后的机械臂不仅满足工作要求,且自身质量减小,提升了机械臂的承载能力与末端执行器精度,增强了排爆工作的安全性。采用3D打印技术制造的机械臂,解决了优化大臂模型复杂、加工困难的问题,提高了设计制造的效率。

3D打印个体化定制枕颈融合系统的三维有限元分析

目的:运用三维有限元分析法对3D打印个体化定制枕颈融合系统(3D printing occipitocervical fusion system,3D-OCF)进行生物力学评价。方法:设计并研制3D-OCF,将该内固定系统与传统Summit内固定系统作对比,建立两套枕颈融合内固定方式的三维有限元模型,模拟术后上颈椎活动,分别在屈伸、侧屈及旋转6种工况下施加40 N垂直载荷及1.5 N·m力矩的预载荷,观察两种内固定系统固定下椎体活动度、枕骨位移峰值及内固定装置的应力分布。结果:在屈伸、侧屈、旋转6种工况下,与传统Summit内固定系统相比,3D-OCF固定的上颈椎各节段活动度明显降低,各节段整体活动度下降73.02%~100.00%;椎体位移峰值,与传统Summit内固定系统相比,3D-OCF固定的颈椎最大位移值明显降低,各个工况下下降了78.09%~95.73%;内固定系统应力分析,在屈伸、侧屈、旋转6种工况下,两套内固定系统所受最大应力值均在前屈状态下,3D-OCF最大应力值为37.43 MPa,Summit内固定系统最大应力值为533.32 MPa。3D-OCF的最大应力值与使用传统Summit内固定系统相比,3D-OCF各个工况的最大应力值明显降低,且各个工况下应力差均衡,无明显应力集中点。结论:3D-OCF能为枕颈融合内固定术能提供足够的强度和稳定性,且3D-OCF装置应力相对较为分散,系统装置发生断裂、失效的可能性小。

3D打印矫正鞋垫晶格支撑结构的有限元分析

矫正鞋垫可通过3D打印技术定制,而支撑鞋垫的拓扑晶格结构可利用有限元分析来探索优化。基于面心立方(FCC)、体心立方(BCC)这2种常规晶格支撑结构建立结构模型,分析寻找最优拓扑结构,并深化构造FCC和BCC复合结构模型,研究结构因子及晶格轮廓对矫正支撑性能的影响。模拟结果显示,相同受力条件下,FCC晶格结构支撑强力较高,同等变形下的抗压力较大;对于由FCC和BCC组成的复合结构,其有限元分析的参数值随着FCC结构在复合模型中所占比例的降低而增加,且FCC占比每减小25%,应力增大约1.03倍。模拟结果证明,FCC结构在支撑矫正鞋垫时具有理论和实用的一致性,能形成良好的足底压力分布。

陶瓷3D打印技术研究进展

3D打印技术因具有加工精度高、成本低、操作简易、制造灵动等优点,被广泛应用于航空航天、汽车、医疗、武器等领域。将3D打印技术与陶瓷成型制造相结合,可以解决很多使用传统陶瓷制造技术带来的问题。3D打印技术主要有喷墨打印技术、浆料直写成型技术、光固化成型技术、陶瓷熔融沉积成型技术、激光选区烧结成型技术。本文概述了各3D打印技术的特点及其研究进展,阐述了光固化成型技术中的陶瓷浆料制备、后处理工艺,讨论了有限元数值模拟在3D陶瓷打印技术领域的应用,分析了氧化硅、碳化硅、氧化铝、氧化锆、陶瓷前驱体、磷酸三钙陶瓷的特性及其应用现状,最后总结了陶瓷3D打印技术目前存在的问题以及未来发展的潜力。

仿生蛛网孔隙结构3D打印个性化钛网设计及三维有限元分析

背景:蜘蛛网结构具有内在的能量耗散机制,使其能承受较大的集中负荷,将其应用到3D打印个性化钛网设计上来减少由于应力集中引起的局部断裂。目的:研究新型仿生蛛网孔隙结构3D打印个性化钛网的设计方法,并应用三维有限元法对其进行生物力学分析。方法:应用锥形束CT、Mimics、Geomagic Wrap、3-matic Research和ANSYS Workbench等软件分别建立仿生蛛网孔隙结构、圆孔结构、方孔结构、六边形孔结构且厚度均为0.3 mm的4组个性化钛网有限元模型,将100 N的载荷加载在牙槽嵴顶对应的钛网上,进行有限元分析。结果与结论:①方孔、圆孔、六边形孔、仿生蛛网孔隙结构个性化钛网最大位移值分别为0.064,0.103,0.107,0.070 mm,等效应力最大分别为1633.5,1611.3,2131.2,1104.8 MPa;②各组固位螺钉在钛网受力后应力分布相似,主要集中在螺钉颈部与钛网相接触部位,方孔、圆孔、六边形孔、仿生蛛网孔隙结构个性化钛网组固位螺钉最大等效应力值分别为149.13,200.32,178.73,163.30 MPa,各组固位螺钉所受到的应力处于安全范围内;③结果显示,仿生蛛网孔隙结构个性化钛网能很好地分散钛网应力,减少应力集中现象;同时,0.3 mm厚度仿生蛛网孔隙结构个性化钛网可以满足大面积颌骨缺损重建机械强度的要求。

A multiscale 3D finite element analysis of fluid/solute transport in mechanically loaded bone

The transport of fluid, nutrients, and signaling molecules in the bone lacunar-canalicular system （LCS） is critical for osteocyte survival and function. We have applied the fluorescence recovery after photobleaching （FRAP） approach to quantify load-induced fluid and solute transport in the LCS in situ, but the measurements were limited to cortical regions 30-50 μm underneath the periosteum due to the constrains of laser penetration. With this work, we aimed to expand our understanding of load-induced fluid and solute transport in both trabecular and cortical bone using a multiscaled image-based finite element analysis （FEA） approach. An intact murine tibia was first re-constructed from microCT images into a three-dimensional （3D） linear elastic FEA model, and the matrix deformations at various locations were calculated under axial loading. A segment of the above 3D model was then imported to the biphasic poroelasticity analysis platform （FEBio） to predict load-induced fluid pressure fields, and interstitial solute/fluid flows through LCS in both cortical and trabecular regions. Further, secondary flow effects such as the shear stress and/or drag force acting on osteocytes, the presumed mechano-sensors in bone, were derived using the previously developed ultrastructural model of Brinkman flow in the canaliculi. The material properties assumed in the FEA models were validated against previously obtained strain and FRAP transport data measured on the cortical cortex. Our results demonstrated the feasibility of this computational approach in estimating the fluid flux in the LCS and the cellular stimulation forces （shear and drag forces） for osteocytes in any cortical and trabecular bone locations, allowing further studies of how the activation of osteocytes correlates with in vivo functional bone formation. The study provides a promising platform to reveal potential cellular mechanisms underlying the anabolic power of exercises and physical activities in treating patients with skeletal deficiencies.

3D finite element analysis on pile-soil interaction of passive pile group

The interaction between pile and soft soil of the passive pile group subjected to soil movement was analyzed with three-dimensional finite element model by using ANSYS software. The soil was assumed to be elastic-plastic complying with the Drucker-Prager yield criterion in the analysis. The large displacement of soil was considered and contact elements were used to evaluate the interaction between pile and soil. The influences of soil depth of layer and number of piles on the lateral pressure of the pile were investigated, and the lateral pressure distributions on the (2×1) pile group and on the (2×2) pile group were compared. The results show that the adjacent surcharge may result in significant lateral movement of the soft soil and considerable pressure on the pile. The pressure acting on the row near the surcharge is higher than that on the other row, due to the "barrier" and arching effects in pile groups. The passive load and its distribution should be taken into account in the design of the passive piles.

3D Finite Element Simulation of Tunnel Boring Machine Construction Processes in Deep Water Conveyance Tunnel

Applying stiffness migration method,a 3D finite element mechanical model is established to simulate the excavation and advance processes.By using 3D nonlinear finite element method,the tunnel boring machine(TBM) excavation process is dynamically simulated to analyze the stress and strain field status of surrounding rock and segment.The maximum tensile stress of segment ring caused by tunnel construction mainly lies in arch bottom and presents zonal distribution.The stress increases slightly and limitedly in the course of excavation.The maximum and minimum displacements of segment,manifesting as zonal distribution,distribute in arch bottom and vault respectively.The displacements slightly increase with the advance of TBM and gradually tend to stability.

3D Finite Elements Technique for Collapse Causes of the Pylons in Egyptian Temples: A Study of the Great Pylon of Ramesseum Temple, Luxor, Egypt

This research presents damage causes of the pylons in the ancient Egyptian temples based on 3D finite elements analysis. The main purpose of the research determines the failure causes of the first pylon of the Ramessium temple, which is situated in Upper Egypt, at Luxor “Thebes” on the west bank of the Nile River. The first pylon of Ramessium temple subjected to seismic activity effects on long term, combined with several structural damage factors such as the defects resulting from the construction technique, where the builder used the poor quality of stones in foundations of the pylon, the building materials residue was used as filler for the core of the pylon walls, and it lacked vertical joints between the courses. In addition to it founded on alluvial soil that is vulnerable to contaminated water, it is still suffering damage factors and urban trespasses at the moment. All of the former factors helped the pylon to be affected by the earthquakes loads that occurred on it. The structural behavior of the pylon under self-weight and earthquakes loads were carried out by Numerical analysis to find out the loads and stresses which caused collapsing of the pylon. Results of the study indicated that the pylon subjected to a horizontal displacement due to old earthquakes force, led to collapse of the pylon. Finally, the study represents use of modern technique to study the structural behavior of the most important architectural units in ancient Egyptian temples to identify the causes of its collapse.

回字形3D打印混凝土受压性能试验及数值模拟

本文将回字形3D打印混凝土试样切割成中心回字型、边缘条纹型和角部拐角型三种类型试块,开展X、Y和Z三个方向的抗压强度试验,并利用基于界面黏结的有限元模型模拟其受压行为,探究回字形3D打印混凝土的强度不均匀性、各向异性和形成机理。结果表明:三种类型试块均为X向(顺打印条带方向)抗压强度最高,Z向(逐层叠加方向)强度最小,其中,中心回字型试块三个方向的平均强度最高,各向异性也最显著,但总体而言三种类型试块的平均强度差异不大;有限元模型的强度计算结果及损伤特征与试验结果基本吻合,说明黏结单元的引入能较好地模拟3D打印混凝土的界面行为;与受力方向垂直的水平界面对强度影响较大,不同加载方向上此类界面的数量和分布不同是导致3D打印混凝土强度各向异性的主要原因。上述研究为3D打印混凝土的打印路径规划提供了参考。

3D打印TPU/PCL共混物食管支架在食管内的生物力学性能

通过静态和动态的有限元数值模拟及体外力学试验,研究不同组分比的3D打印热塑性聚氨酯(TPU)/聚己内酯(PCL)共混物支架与食管模型之间的生物力学特性,实现对支架植入后食管生物力学表征的预测。采用Abaqus软件对支架植入释放、吞咽收缩和动态迁移过程进行有限元模拟,结合力学试验,对食管模型的收缩率、抗迁移力和管壁应力等指标进行量化、比较和分析。结果表明该支架具有良好的径向性能,能在吞咽压力下保持正常形状且无较大变形,而且比商用食管支架对食管产生的最大等效应力小,可以缓解患者的不适。有限元模拟结果与试验结果吻合度较好。使用有限元方法结合3D打印技术可以快速模拟支架的生物力学性能,并反馈到支架的设计上,优化3D打印共混物支架的制造参数。通过有限元模拟真实的生物力学环境,可以更直观地体现支架植入的治疗效果,为支架的设计和临床选择提供科学的建议。

基于PLAXIS 3D模型的地铁旁深基坑开挖有限元分析

以天津鲁能绿荫里项目深基坑降水及土方开挖工程为研究对象,采用岩土工程有限元分析软件PLAXIS 3D进行模型构建,研究深基坑土方开挖对邻近既有地铁结构及隧道的影响,探究影响土体沉降量及结构变形的因素,验证施工工艺的可行性,并进行总结。研究表明,土方开挖后基坑周围会出现沉降带现象且基坑围护结构会向内凹进;采用分步开挖的施工方法对减轻基坑施工对地铁站及隧道的影响有积极作用;相邻基坑存在力的传递,此区域围护结构变形及沉降较大。

3D打印前臂外固定支具的有限元分析与结构优化设计

背景:使用3D打印技术制作适合患者个性化的支具普遍存在,但却缺乏支具对前臂骨折断裂处保护效果的生物力学验证。目的:将逆向建模、有限元分析与拓扑优化等方法相结合,提出一种3D打印制作前臂支具的可行性方法,并通过有限元分析验证支具的有效性。方法:采用逆向建模方法,通过医学图像处理软件Mimics构建1例男性志愿者前臂模型,并利用参数化设计软件Grasshopper对Rodin 4D采集的前臂数据进行处理并建立支具模型。依据前臂生物力学特性对佩戴支具的前臂整体模型进行有限元分析,再根据有限元分析结果对支具进行拓扑优化并作打孔处理,最后用3D打印机将支具打印出来。结果与结论:(1)在100 N的压力载荷下,骨折断裂处应力与位移分别为1.53 MPa和0.27 mm,而前臂在支具保护下断裂处的应力与位移分别下降到0.19 MPa和0.005 mm;(2)在保证支具力学性能前提下对支具进行拓扑优化,通过对比优化后支具的支承刚度结果,选择减少40%体积作为优化结果,再根据优化结果使用Grasshopper插件对支具进行打孔减材处理;(3)通过对比由不同文样镂空设计的支具强度,选择泰森多边形作为打孔文样;(4)提出使用数字化设计与3D打印技术制作的前臂支具具有可行性,实验建立了完整的前臂支具设计、验证及制造系统。

A 3D Numerical Simulation of Sand Drain Element in the Soft Soil of Guangzhou-Zhujiang Highway,China

The behavior of sand drain was estimated so that the size of very large load-pressure could be eliminated by changing the configuration of the sand drain elements into sand wall.A 3D mathematical model was formulated to transform the configuration of a sand drain into a sand wall to minimize or eliminate the excessive stress and primary settlement on the road base.This was barely considered in the past. According to soil mechanics theory and seepage characteristics of sand drain in road base foundations, a 3D sand drain element in FEM format was generated,and a matrix expression was formulated which was introduced into 3D Biot Consolidation