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.

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 of a Man Hip Joint Femur under Impact Loads

Objective： The biomechanical characters of the bone fracture of the man femoral hip joint under impact loads are explored. Methods ：A biosystem model of the man femoral hip joint by using the GE （ General Electric） lightspeed multi-lay spiral CT is conducted. A 3D finite element model is established by employing the finite element software ANSYS. The FE analysis mainly concentrates on the effects of the impact directions arising from intense movements and the parenchyma on the femoral hip joint on the stress distributions of the proximal femur. Results：The parenchyma on the hip joint has relatively large relaxation effect on the impact loads. Conclusion：Effects of the angle δ of the impact load to the anterior direction and the angle γ of the impact load to the femur shaft on the bone fracture are given;δ has larger effect on the stress and strain distributions than the angle γ,which mainly represents the fracture of the upper femur including the femoral neck fracture when the posterolateral femur is impacted, consistent with the clinical resuits.

Optimal Design Strategies of Femur Tumor Hyperthermia Based on Finite Element Analysis of Temperature Field

A 3D femoral model was built to obtain the three-dimensional temperature distribution of femur and its surrounding tissues and provide references for clinical applications. According to the relationship between gray-value and material properties,the model was assigned with various materials to make sure that it is more similar to the real femur in geometry and physical properties. 3D temperature distribution is obtained by using finite element analysis software ANSYS 11. 0 on the basis of heat conduction theory,Laplace equation,Pennes bio-heat transfer equation,thermo physical parameters of bone tissues,the boundary condition,and initial conditions. Taken the asymmetry of the 3D distribution of temperature into account,it is necessary to adopt the heating method with multiple heat sources. This method can ensure that the temperature fields match well with the tumor tissues and kill the tumor cells efficiently under the condition of protecting the normal tissues from damage. The analysis results supply important guidance for determining the needle position and the needle number and controlling the intensity of heating.

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.

Biomechanical analysis of an absorbable material for treating fractures of the inferior orbital wall

AIM:To investigate the biomechanical properties and practical application of absorbable materials in orbital fracture repair.METHODS:The three-dimensional(3D)model of orbital blowout fractures was reconstructed using Mimics21.0 software.The repair guide plate model for inferior orbital wall fracture was designed using 3-matic13.0 and Geomagic wrap 21.0 software.The finite element model of orbital blowout fracture and absorbable repair plate was established using 3-matic13.0 and ANSYS Workbench 21.0 software.The mechanical response of absorbable plates,with thicknesses of 0.6 and 1.2 mm,was modeled after their placement in the orbit.Two patients with inferior orbital wall fractures volunteered to receive single-layer and double-layer absorbable plates combined with 3D printing technology to facilitate surgical treatment of orbital wall fractures.RESULTS:The finite element models of orbital blowout fracture and absorbable plate were successfully established.Finite element analysis(FEA)showed that when the Young’s modulus of the absorbable plate decreases to 3.15 MPa,the repair material with a thickness of 0.6 mm was influenced by the gravitational forces of the orbital contents,resulting in a maximum total deformation of approximately 3.3 mm.Conversely,when the absorbable plate was 1.2 mm thick,the overall maximum total deformation was around 0.4 mm.The half-year follow-up results of the clinical cases confirmed that the absorbable plate with a thickness of 1.2 mm had smaller maximum total deformation and better clinical efficacy.CONCLUSION:The biomechanical analysis observations in this study are largely consistent with the clinical situation.The use of double-layer absorbable plates in conjunction with 3D printing technology is recommended to support surgical treatment of infraorbital wall blowout fractures.

Stochastic analysis of excavation-induced wall deflection and box culvert settlement considering spatial variability of soil stiffness

In this study, a three-dimensional (3D) finite element modelling (FEM) analysis is carried out to investigate the effects of soil spatial variability on the response of retaining walls and an adjacent box culvert due to a braced excavation. The spatial variability of soil stiffness is modelled using a variogram and calibrated by high-quality experimental data. Multiple random field samples (RFSs) of soil stiffness are generated using geostatistical analysis and mapped onto a finite element mesh for stochastic analysis of excavation-induced structural responses by Monte Carlo simulation. It is found that the spatial variability of soil stiffness can be described by an exponential variogram, and the associated vertical correlation length is varied from 1.3 m to 1.6 m. It also reveals that the spatial variability of soil stiffness has a significant effect on the variations of retaining wall deflections and box culvert settlements. The ignorance of spatial variability in 3D FEM can result in an underestimation of lateral wall deflections and culvert settlements. Thus, the stochastic structural responses obtained from the 3D analysis could serve as an effective aid for probabilistic design and analysis of excavations.

A New Finite Element Model with Manufactured Error for Additive Manufacturing

Additive manufacturing(AM),adding materials layer by layer,can be used to produce objects of almost any shape or geometry.However,AM techniques cannot accurately build parts with large overhangs,especially for the large features close to horizontal,hanging over the void.The overhangs will make the manufactured model deviate from the design model,which will result in the performance of the manufactured model that cannot satisfy the design requirements.In this paper,we will propose a new finite element(FE)analysis model that includes the manufacturing errors by mimicking the AM layer by layer construction process.In such FE model,an overhang coefficient is introduced to each FE,which is defined by the support elements in the lower layer.By mimicking the AM process from the bottom layer to the top layer,all the FE properties are updated based on their overhang coefficients,which makes the computational model be able to predict the manufactured model with manufacturing errors.The proposed model can be used to predict the performance of the AM objects in the design stage,which will help the designers to improve their design by the simulation results.

3D Design and Analysis of Crushing Roller of High-pressure Grinding Roller

Crushing roller is one of the main parts of High-p re ssure Grinding Roller, which is a kind of high efficient ore crushing equipment. A kind of assembled roller, which is more convenient to renovate worn surface b y simply replacing segmented surface of the roller, was developed. The structura l models of assembled roller’s components were designed with SolidWorks softwar e based on feature modeling, these solid models of the roller were virtually ass embled. Through this work, not only was the assemble interference checked out so as to examine validity of the structure design, but also these solid models cou ld be recognized by COSMOS/Works software, through which the finite element an alysis can be done. Then the stress and displacement of the main shaft and sur face segment in two different working states were analyzed and detected quickly according to the analysis results with COSMOS/Works. In conclusion, the optimum clearance of 1.0～2.0 mm between concave-convex studded segments is determined to make the using life of assembled roller longer.

Analysis of the Magnetic Flux Density, the Magnetic Force and the Torque in a 3D Brushless DC Motor

As permanent magnet motors and generators produce torque, vibration occurs through the small air gap due to the alternating magnetic forces created by the rotating permanent magnets and the current switching of the coils. The magnetic force can be calculated from the flux density by finite element methods and the Maxwell stress tensor in cy-lindrical coordinates. In this paper the magnetic flux density, the magnetic force and the torque of a real three dimen-sional brushless DC motor are simulated using Maxwell 3 D V 11.1.

Numerical Investigation of Laser Surface Hardening of AISI 4340 Using 3D FEM Model for Thermal Analysis of Different Laser Scanning Patterns

Laser surface hardening is becoming one of the most successful heat treatment processes for improving wear and fatigue properties of steel parts. In this process, the heating system parameters and the material properties have important effects on the achieved hardened surface characteristics. The control of these variables using predictive modeling strategies leads to the desired surface properties without following the fastidious trial and error method. However, when the dimensions of the surface to be treated are larger than the cross section of the laser beam, various laser scanning patterns can be used. Due to their effects on the hardened surface properties, the attributes of the selected scanning patterns become significant variables in the process. This paper presents numerical and experimental investigations of four scanning patterns for laser surface hardening of AISI 4340 steel. The investigations are based on exhaustive modelling and simulation efforts carried out using a 3D finite element thermal analysis and structured experimental study according to Taguchi method. The temperature distribution and the hardness profile attributes are used to evaluate the effects of heating parameters and patterns design parameters on the hardened surface characteristics. This is very useful for integrating the scanning patterns’ features in an efficient predictive modeling approach. A structured experimental design combined to improved statistical analysis tools is used to assess the 3D model performance. The experiments are performed on a 3 kW Nd:Yag laser system. The modeling results exhibit a great agreement between the predicted and measured values for the hardened surface characteristics. The model evaluation reveals also its ability to provide not only accurate and robust predictions of the temperature distribution and the hardness profile as well an in-depth analysis of the effects of the process parameters.

Structural Mechanics Analysis Using an FE-Mesh Adaption to Real, 3D Surface Detected Geometry Data

Within today＇s product development process, various FE-simulations （finite element） for the functional validation of the desired characteristics are made to avoid expensive testing with real components. Those simulations are performed with great effort for discretization, use of simulations conditions, like taking different non-linearities （i.e., material behavior, etc.） into account, to create meaningful results. Despite knowing the effects of deformations occurring during the production processes, always the non-deformed design model of a CAD-system （computer aided design） is used for the FE-simulations. It seems rather doubtful that further refinement of simulation methods makes sense, if the real manufactured geometry of the component is not considered for in the simulation. For an efficient exploit of the potential of simulation methods, an approach has been developed which offers a geometry model for simulation based on the existing CAD-model but with integrated production deviations as soon as a first prototype is at hand by adapting the FE-mesh to the real, 3D surface detected geometry.

3D Nonlinear Analysis of the Preloading Filling Spiral Case of the Jinping-I Hydropower Station

In consideration of the contact between the steel spiral casing and the peripheral reinforced concrete, a nonlinear analysis for the combined bearing structure of the JinPing-I preloading filling spiral case has been made with ANSYS. Contrasts of the stress of the reinforcing bars, the biggest width of the crack and the outspread section of the crack has been made with the different parameters of preloading pressure and reinforcement scheme, resulting in a reasonable preloading pressure and reinforcement scheme. This conclusion has been applied to the spiral casing of JinPing-I hydropower station.

3D finite element analysis of a two-surface wear model in fretting tests

This article aims at developing a computationally efficient framework to simulate the erosion of two contact surfaces in three-dimensional(3D),depending on the body resistance.The framework involves finite element(FE)resolution of a fretting problem,wear computation via a non-local criterion including a wear distribution parameter(WDP),as well as updating of the geometry and automatic remeshing.Its originality is based on the capability to capture the damage on each surface and obtain local and global results for a quantitative and qualitative analysis.Numerical simulations are carried out for two 3D contact specimens with different values of WDP.The results highlight the importance of correctly modelling wear:One-surface wear model is sufficient from a global point of view(wear volume),or whenever the wear resistance for a body is much higher than that of another one,whereas a 3D two-surface wear model is essential to capturing local effects(contact pressure,wear footprint,etc.)related to the difference in wear resistance of the bodies.

Evaluation of labial versus labio-inferior lines of osteosynthesis using 3D miniplate for fractures of anterior mandible:A finite element analysis with a pilot clinical trial

Purpose:The fractures of anterior mandible are subject to severe torsional forces due to muscles acting in opposite directions.3D miniplate has been suggested as a good alternative by some researchers.However,finite element model(FEM)studies indicate that labio-inferior positioning of two miniplates perpendicular to each other offers better stability as compared to labial positioning.This study aims at combining the advantages of a single 3D miniplate and labio-inferior positioning of two conventional miniplates,which was assessed by finite element analysis along with a pilot clinical trial.Methods:Two FEM models were created using CT data of a 24-year-old patient with Angie class I occlusion:control model with labial plating and study model with labio-inferior plating.The models were processed with MIMICS.(materialise,Leuven,Belgium),CATIA.(Dassault Systemes)and finite element analysis softwares.Parameters adopted for analysis were(1)displacement(mm)of fracture fragments during each screw fixation,(2)lingual splay and post fixation stability of fracture fragments with masticatory load,and(3)stress distribution(MPa)across fracture fragments.Moreover,a pilot clinical trial including five patients with anterior mandible fracture was conducted.The fractures were managed by intraoral open reduction and 3D miniplate fixation in labio-inferior position.Intraoperative interfragmentary gap,post fixation lingual splay and radiographic fracture union and complications were assessed clinically.Results:Labio-inferior plating demonstrated less displacement(mm)of fracture fragments during screw fixation(0.059 vs.0.079)as well as after application of masticatory load(1.805 vs.1.860).Negligible lingual splay and less stress distribution(MPa)across fracture fragments(1.860 vs.1.847)were appreciated in the study group as compared to control group.Clinical trial support the favorable outcome related to intraoperative and postoperative assessment parameters.Conclusion:FEM analysis and clinical trial reveal better results with labio-inferior positioning of 3D miniplate when compared to labial positioning.

Maxwell 3D在开关磁阻平面电机结构设计中的应用

利用Maxwell3D电磁场有限元分析软件对开关磁阻平面电机结构进行优化设计。对两种电机结构(动子宽齿结构、动子等齿结构)进行3D静磁场建模与仿真,获得磁场分布特性和电磁推力特性。仿真结果表明,等齿结构与宽齿结构相比,饱和程度低,而且等齿结构电磁推力的最大值较大,可控范围宽,即等齿结构要优于宽齿结构。仿真结果为电机结构设计和研制提供了一定的理论依据。

粒料3D打印机机头传热结构优化设计

在熔融沉积成型制造技术中,热流道及喷头的温度场对聚合物的流动及沉积有很大影响。针对现有的聚合物熔体微分粒料3D打印机,建立机头的三维模型,运用有限元分析的方法得到其温度场分布。模拟结果表明,热源与喷头之间存在较大温差,且热流道温度分布不均匀。针对以上结构的缺点,提出机头结构的优化方案,并对其所用材料进行改进。对优化后的机头再次进行有限元热分析,分析结果表明,优化后的机头热源与喷头之间的温差显著减小,且热流道的温度分布趋于均匀。因此,3D打印机机头结构优化方案对于聚合物熔体的稳定输送及沉积成型有重要意义。

Effect of 3D anchorage attachment on the alleviating tipping/extrusion of premolars for en-mass distalization of maxillary molars with clear aligners:A finite element study

This study aimed to explore the optimal invisible orthodontic force system during the en-mass distalization of two maxillary molars to minimize the side effect of anchorage loss by changing the direction of the application of the orthodontic force system.A high bio-fidelity 3D finite element model including maxilla,periodontal ligament,dentition,clear aligner,3D anchorage attachment and mini-implant was established.Different lengths of lateral hooks of 3D-printed anchorage attachments and mini-implant positions into the palatal alveolus were considered.A 200 g distal force was applied to the lateral hooks of different horizontal lengths(3.26 mm,6.52 mm and 9.78 mm)with the mini-implant as the application point.Using ABAQUS software,orthodontic tooth movements under 12 different clinical treatment designs were analyzed and calculated.The 3D anchorage attachment enhanced the anchorage of anterior teeth and alleviated the tipping/extrusion of premolars.In contrast to without clear aligners,length of the lateral hook had a negligible effect on both mesial tipping and buccal tipping with clear aligners,which could then be ignored.The change in mesial tipping was less and nearly remained constant despite of the different heights of the mini-implant.The 3D anchorage attachment assisted clear aligner can avoid the side effects of anterior tooth proclination caused by insufficient anchorage.The length of the lateral hook,and height of the mini-implant in this invisible orthodontic force system hardly affects the tooth movement of anchorage units.Clear aligners can effectively control the rotation and tipping of anchorage units caused by 3D anchorage attachment.

3D打印柔性材料特性及有限元分析方法研究

针对3D打印柔性材料特性及有限元分析问题,对3D打印柔性试件的力学特性和有限元仿真方法进行了研究。通过对不同打印条件的柔性试件进行了单轴拉伸实验,测量了试件的力学特性,得到了打印条件对试件弹性模量和泊松比的影响;利用单轴拉伸实验得到的应力应变数据和不同的Abaqus有限元仿真方法对试件进行了分析,得到了3D打印柔性材料的最佳仿真方法,并利用复杂结构零件的仿真结果对仿真方法进行了验证。研究结果表明:层高和打印方向会影响3D打印柔性试件的弹性模量和泊松比;不同打印条件的试件可等效为不同材料的试件进行仿真,将3D打印柔性材料设置为超弹性体时仿真效果最好。

Evaluating performance of lignite pillars with 2D approximation techniques and 3D numerical analyses

This paper attempts to investigate the use of approximate 2D numerical simulation techniques for the evaluation of lignite pillar geomechanical response, formed via the room and pillar mining method.Performance and applicability of the developing methodology are assessed through benchmarking with a more direct and accurate 3D numerical model. This analysis utilizes an underground lignite mine which is being developed in soft rock environment. Through the decisions made for the optimum room and pillar layout, the design process highlights the strong points and the weaknesses of 2D finite element analysis, and provides useful recommendations for future reference. The interpretations of results demonstrate that 2D approximation techniques come near quite well to the actual 3D problem.However, external load approximation technique seems to fit even better with the respective outcomes from the 3D analyses.