The Improvement on the Determining Method of the Proper Pile Length in the Collapse Loess

2013 ◽  
Vol 353-356 ◽  
pp. 725-729
Author(s):  
Gen Sheng Zhao ◽  
Wei Wei ◽  
Huan Tao Zhou ◽  
Qi Zhang
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Skin Friction ◽  
Element Model ◽  
The Self ◽  
Engineering Practice ◽  
Superposition Method ◽  
Practical Application ◽  
Friction Resistance ◽  
Pile Length

In Consideration of the nonlinear of the soil and the interface between pile and soil, the spatial axisymmetry finite element model is established. Based on the model, the paper offers the Superposition Method to calculate proper pile length in the self-weight collapse loess , and gets the following deduction: when the upper and lower parts of soils skin friction has the same regularity, added pile length L has nothing to do with the skin friction distribution, but is related to ultimate friction resistance. Practical application shows that the method is effective and can be referenced in engineering practice.

scholarly journals Experimental Study of Friction Resistance between Steel and Concrete in Prefabricated Composite Beam with High-Strength Frictional Bolt

2020 ◽  
Vol 2020 ◽  
pp. 1-13 ◽  
Author(s):  
Qi Guo ◽  
Qing-wei Chen ◽  
Ying Xing ◽  
Ya-ning Xu ◽  
Yi Zhu
Keyword(s):  
Finite Element ◽  
Friction Coefficient ◽  
Finite Element Model ◽  
Bearing Capacity ◽  
Concrete Strength ◽  
High Strength ◽  
Element Model ◽  
Construction Time ◽  
Friction Behavior ◽  
Friction Resistance

Prefabrication of composites beam reduces the construction time and makes them easily to be assembled, deconstructed, and partially repaired. The use of high-strength frictional bolt shear connectors can greatly enhance the sustainability of infrastructure. However, researches about the concrete-steel friction behavior are very limited. To provide a contribution to this area, 21 tests were conducted to measure the friction coefficient and slip stiffness with different concrete strength, steel strength, and surface treatment of steel. An effective finite element model was developed to investigate the ultimate bearing capacity and load-slip characteristics of bolt shear connection. The accuracy of the proposed finite element model is validated by the tests in this paper. The results demonstrate a positive correlation between concrete strength and friction coefficient and better performance of shot-blasted steel. It is also proved that high-strength frictional bolt has a 30% lower bearing capacity but better strength reserve and antiuplifting than the headed stud.

A Three-Dimensional Coupled Finite Element Model for the Simulation of Stress Corrosion on Pipeline Steel

2019 ◽  
Author(s):  
Dongxu Sun ◽  
Ming Wu ◽  
Fei Xie ◽  
Ke Gong
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Stress Corrosion ◽  
Corrosion Behavior ◽  
Pipeline Steel ◽  
Three Dimensional ◽  
Element Model ◽  
Circumferential Direction ◽  
The Self ◽  
Corrosion Defect

Abstract In this study, a three-dimensional finite element model was constructed to study the stress corrosion behavior of pipeline steel. Stress analysis and electrochemical calculation were incorporated into the model through multiphysics field coupling technique. Tensile property and electrochemical corrosion behavior of X70 pipeline steel were measured by experiments to formulate the model. The modeling results show that the corrosion is accelerated on the surface of corrosion defect where the stress tends to concentrate because of mechanoelectrochemical effect. The effect of elastic strain on corrosion enhancement is not obvious. The plastic deformation on defect bottom increases the corrosion rate significantly, especially for the conditions with high operating pressure or large defect depth. The corrosion current distribution indicated that the “self-acceleration effect” exists on corrosion defect. This effect makes the corrosion develop to depth and the shape of corrosion defects is more likely to cause stress concentration, and finally induces corrosion perforation or cracking. The two directions, i.e. axial and circumferential direction, have the different stress corrosion behaviors. The “self-acceleration effect” is more obvious on circumferential direction than that on axial direction, which can explain the phenomenon that there are mostly axial stress corrosion cracks on the pipeline in field.

scholarly journals Finite Element Model Fractional Steps Updating Strategy for Spatial Lattice Structures Based on Generalized Regression Neural Network

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
Caiwei Liu ◽  
Jijun Miao ◽  
Changyong Zhao
Keyword(s):  
Neural Network ◽  
Finite Element ◽  
Finite Element Model ◽  
Model Updating ◽  
Element Model ◽  
Engineering Practice ◽  
Measuring Point ◽  
Stiffness Reduction ◽  
Spatial Lattice ◽  
Ball Joints

In order to get a more accurate finite element model of a spatial lattice structure with bolt-ball joints for health monitoring, a method of modifying the bolt-ball joint stiffness coefficient was proposed. Firstly, the beam element with adjustable stiffness was used in the joint zone in this paper to reveal the semirigid characteristic of the joint. Secondly, the value of stiffness reduction factor (ar) was limited in the range of[0.2,0.8]and the reference value (ar0) of it was suggested to be 0.5 based on referenced literatures. Finally, the finite element model fractional steps updating strategy based on neural network technique was applied and the limited measuring point information was used to form the network input parameter. A single-layer latticed cylindrical shell model with 157 joints and 414 tubes was used in a shaking TABLE test. Based on the measured modal data, the presented method was verified. The results show that this model updating technique can reflect the true dynamic characters of the shell structure better. Moreover, the neural network can be simplified considerably by using this algorithm. The method can be used for model updating of a latticed shell with bolt-ball joints and has great value in engineering practice.

Modal Analysis Method for Blisks Based on Three-Dimensional Blade and Two-Dimensional Axisymmetric Disk Finite Element Model

2016 ◽  
Vol 139 (5) ◽  
Author(s):  
Wangbai Pan ◽  
Guoan Tang ◽  
Meiyan Zhang
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Modal Analysis ◽  
Degrees Of Freedom ◽  
Mechanical Energy ◽  
Three Dimensional ◽  
Element Model ◽  
Computational Time ◽  
Engineering Practice ◽  
Analysis Method

In this paper, a novel and efficient modal analysis method is raised to work on blisk structures based on mixed-dimension finite element model (MDFEM). The blade and the disk are modeled separately. The blade model is figured by 3D solid elements considering its complex configuration and its degrees-of-freedom (DOFs) are condensed by dynamic substructural method. Meanwhile, the disk is structured by 2D axisymmetric element developed specially in this paper. The DOFs of entire blisk are tremendously reduced by this modeling approach. The key idea of this method is derivation of displacement compatibility to different dimensional models. Mechanical energy equivalence and summation further contribute to the model synthesis and modal analysis of blade and disk. This method has been successfully applied on the modal analysis of blisk structures in turbine, which reveals its effectiveness and proves that this method reduces the computational time expenses while maintaining the precision performances of full 3D model. Though there is limitation that structure should have proper coverage of blades, this method is still feasible for most blisks in engineering practice.

Finite Element Analysis of the Effect of Core Pile in Combined Composite Foundation

2012 ◽  
Vol 594-597 ◽  
pp. 608-611
Author(s):  
Shao Dong Liu ◽  
Wei Guo ◽  
Xin Zheng
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Finite Element Model ◽  
Carrying Capacity ◽  
Element Model ◽  
Composite Foundation ◽  
Element Analysis ◽  
The Core ◽  
Optimal Value ◽  
Pile Length

Combined composite foundation has been widely used in actual projects, but its working behaviors need to be studied further. By establishing finite element model, the effect of the core pile was researched. Analysis shows that, the diameter and the length of core pile affect the bearing capacity of combined composite foundation significantly. There is an optimal value of the length and the diameter of core pile, which can make the foundation generate maximum carrying capacity. With the increase of core pile length, the depth of neutral point increased.

Strength check of a three-row roller slewing bearing based on a mixed finite element model

2016 ◽  
Vol 231 (18) ◽  
pp. 3393-3400 ◽  
Author(s):  
Yunfeng Li ◽  
Di Jiang
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Internal Stress ◽  
Contact Stress ◽  
Mixed Finite Element ◽  
Element Model ◽  
Structural Deformation ◽  
Engineering Practice ◽  
Slewing Bearing ◽  
Bearing Rings

For the two failure modes of a three-row roller slewing bearing, ring fracture and raceway spalling, a method for checking the strength of a slewing bearing through finite element analysis is proposed. This method calculates the internal stress distribution of the bearing rings by using the mixed finite element model with both solid elements and spring elements of the slewing bearing assembly and checks the bearing structural strength by using the maximum internal stress of the bearing rings. The method also calculates the contact stress between the roller and raceways by using the entity contact model between the roller and the raceways; the obtained maximum contact stress is used to check the contact strength of the slewing bearing. The proposed mixed finite element model considers the structural deformation of the bearing rings, and the calculated results can reflect the real situation more accurately than the traditional analytical model with the hypothesis of rigid ring. The proposed method also avoids the solution problem, which has large-scale calculation and difficulty of convergence of the entity finite element model of a slewing bearing, and the calculation efficiency is improved effectively. The calculated results by mixed finite element model are consistent with the failure mode of this type of slewing bearing in engineering practice.

Stress Analysis of Hygrothermal Delamination of Quad Flat No-Lead (QFN) Packages

2008 ◽  
Author(s):  
Minshu Zhang ◽  
S. W. Ricky Lee ◽  
Xuejun Fan
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Thermal Loading ◽  
Element Model ◽  
Interfacial Stress ◽  
Moisture Distribution ◽  
Superposition Method ◽  
Element Analysis ◽  
Interfacial Delamination ◽  
Simulation And Experiment

Interfacial delamination is a major reliability issue of Quad Flat No-lead (QFN) packages under the JEDEC-MSL preconditioning and reflow process. Failures will occur when the hygrothermal stress exceeds the interfacial strength. Simulation based on finite element model is a popular method for studying the failure mechanism. However, the non-accurate material properties and the lack of experiment validations always constrain the Finite Element Analysis (FEA) at the artificial parametric study stage. To further investigate the interfacial delamination, a complex system including both simulation and experiment validation is established in this study. A dummy QFN is fabricated first as the test vehicle for the subsequent study. Then the related finite element model is built to reveal the interfacial stress distribution when the packages are subjected to the pure thermal loading and hygrothermal loading, respectively. Once the interfacial stress is derived, the strength approach is applied here to indicate the high risk area where delamination will occur. Finally, the analyses from simulation are verified by Moisture Sensitivity Level (MSL) tests using dummy samples. In this paper, a superposition method is used to integrate the thermo-mechanical and hygro-mechanical stress, with considering the non-uniform moisture distribution during reflow. Such a method is different from the previously method in literature. Results show that the shear stress is dominant along all the interfaces. From the comparison between simulation and experiments, the strength approach is applied to evaluate the package reliability successfully. Both simulation and experiment results show that the molding compound/lead-frame interface around the junction of die attach fillet would be the initiation of delamination.

scholarly journals Friction-Induced Vibration of a Railway Wheelset-Track System and Its Effect on Rail Corrugation

Lubricants ◽  
2020 ◽  
Vol 8 (2) ◽  
pp. 18
Author(s):  
Guangxiong Chen
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Element Model ◽  
The Self ◽  
3D Finite Element ◽  
Rail Corrugation ◽  
Track System ◽  
Excited Vibration ◽  
Creep Force ◽  
Friction Induced Vibration

In the present study, the effect of the radius of railway curved tracks on the slip of a wheel on a rail is studied. A 3D finite-element model of a wheelset-track system is established when the creep force between the wheel and rail is saturated. The occurrence propensity of the self-excited vibration of the wheelset-track system is predicted. It is concluded that the radius of curved tracks has a strong effect on the slip of wheels on rails. In the tightly curved tracks, the slip of the wheel of the leading wheelset on the rail always occurs. The wheelset-track system has a strong occurrence propensity for unstable vibrations on the tightly curved tracks. The accuracy of the rail corrugation prediction based on the unstable vibrations of wheelset-track systems is determined to be 85–90% or higher.

Topological Optimization Design of Cistern Stents of the Planomiller Machine Based on Hyperworks

2011 ◽  
Vol 421 ◽  
pp. 423-426
Author(s):  
Fu Yun Liu ◽  
Ying Sun ◽  
Tian Chao Yu
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Optimization Design ◽  
Element Model ◽  
Topological Optimization ◽  
Structural Deformation ◽  
Engineering Practice ◽  
Geometry Model ◽  
Design Variables ◽  
The Finite Element Model

Planomiller is a milling machine that widely used in processes of large parts. Cistern stents is a component of planomiller supporting the sink. In this paper, topological optimization of Cistern stents is implemented to reduce its weight. Firstly geometry model of Cistern stents is built in SolidWorks, a finite element model of Cistern stents is established. Then loads and boundary conditions are loaded to the finite element model according to engineering practice. Finally density of units is set as the design variables, energy of structural deformation is set as the objective function, Cistern stents can be optimized by optimizing analysis. The compared results show that the proposed optimization design is effective.

The Study on Simulation Static Load Test Base on Flexibility Matrix

2012 ◽  
Vol 178-181 ◽  
pp. 2048-2051
Author(s):  
Xian Min Zhang ◽  
Yan Gao
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Static Load ◽  
Element Model ◽  
Load Test ◽  
Actual State ◽  
Engineering Practice ◽  
Static Load Test ◽  
Flexibility Matrix ◽  
The Finite Element Model

Through the measured simply supported bridge's dynamic parameters, we can establish the finite element model of the structure.As the flexibility matrix can reflect the actual state of the bridge, making the actual measured flexibility matrix as a basis to inverse the bridge’s finite element model .Combined with the engineering practice static load test, we can assess the bearing capacity of the bridge according to inversion model bridge.

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