Application of the finite element submodeling technique in a single point contact and wear problem

In view of the problems of low accuracy, small rotational angle, and large impact caused by flexure joints during the deployment process, an integrated flexure revolute (FR) joint for folding mechanisms was designed. The design was based on the method of compliance and stiffness ellipsoids, using a compliant dyad building block as its flexible unit. Using the single-point synthesis method, the parameterized model of the flexible unit was established to achieve a reasonable allocation of flexibility in different directions. Based on the single-parameter error analysis, two error models were established to evaluate the designed flexure joint. The rotational stiffness, the translational stiffness, and the maximum rotational angle of the joints were analyzed by nonlinear finite element analyses. The rotational angle of one joint can reach 25.5° in one direction. The rotational angle of the series FR joint can achieve 50° in one direction. Experiments on single and series flexure joints were carried out to verify the correctness of the design and analysis of the flexure joint.

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Electromigration-induced directional steps towards the formation of single atomic Ag contacts

Beilstein Journal of Nanotechnology ◽

10.3762/bjnano.11.55 ◽

2020 ◽

Vol 11 ◽

pp. 680-687

Author(s):

Atasi Chatterjee ◽

Christoph Tegenkamp ◽

Herbert Pfnür

Keyword(s):

Fourier Transforms ◽

Single Point ◽

Point Contact ◽

Single Atom ◽

Point Contacts ◽

Cross Sectional ◽

Shell Effects ◽

Theoretical Approaches ◽

Average Grain Size ◽

Thinning Process

Even though there have been many experimental attempts and theoretical approaches to understand the process of electromigration (EM), it has not been quantitatively understood for ultrathin structures and at grain boundaries. Nevertheless, we showed recently that it can be used reliably for the formation of single atomic point contacts after careful pre-structuring of the initial Ag nanostructures. The process of formation of nanocontacts by EM down to a single-atom point contact was investigated for ultrathin (5 nm) Ag structures at 100 K by measuring the conductance as a function of the time during EM. In this paper, we compare the process of thinning by EM of structures with constrictions below the average grain size of Ag layers (15 nm) with that of structures with much larger initial constrictions of around 150 nm having multiple grains at the centre constriction prior to the formation of a point contact. Even though clear morphological differences exist between both types of structures, quantized conductance plateaus showing the formation of single point contacts have been observed for both. Here we put emphasis on the thinning process by EM, just before a point contact is formed. To understand this thinning process, the semi-classical regime before the contact reaches the quantum regime was analyzed in detail. For this purpose, we used experimental conductance histograms in the range between 2G 0 and 15G 0 and their corresponding Fourier transforms (FTs). The FT analysis of the conductance histograms exhibits a clear preference for thinning along the [100] direction. Using well-established models, both atom-by-atom steps and ranges of stability, presumably caused by electronic shell effects, can be discriminated. Although the directional motion of atoms during EM leads to specific properties such as the instabilities mentioned, similarities to mechanically opened contacts with respect to cross-sectional stability were found.

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A Full-System Approach of the Elastohydrodynamic Line/Point Contact Problem

Journal of Tribology ◽

10.1115/1.2842246 ◽

2008 ◽

Vol 130 (2) ◽

Cited By ~ 61

Author(s):

W. Habchi ◽

D. Eyheramendy ◽

P. Vergne ◽

G. Morales-Espejel

Keyword(s):

Finite Element ◽

Nonlinear System ◽

System Approach ◽

Jacobian Matrix ◽

Point Contact ◽

System Of Equations ◽

Nonlinear System Of Equations ◽

Full System ◽

Element Discretization ◽

Fully Coupled

The solution of the elastohydrodynamic lubrication (EHL) problem involves the simultaneous resolution of the hydrodynamic (Reynolds equation) and elastic problems (elastic deformation of the contacting surfaces). Up to now, most of the numerical works dealing with the modeling of the isothermal EHL problem were based on a weak coupling resolution of the Reynolds and elasticity equations (semi-system approach). The latter were solved separately using iterative schemes and a finite difference discretization. Very few authors attempted to solve the problem in a fully coupled way, thus solving both equations simultaneously (full-system approach). These attempts suffered from a major drawback which is the almost full Jacobian matrix of the nonlinear system of equations. This work presents a new approach for solving the fully coupled isothermal elastohydrodynamic problem using a finite element discretization of the corresponding equations. The use of the finite element method allows the use of variable unstructured meshing and different types of elements within the same model which leads to a reduced size of the problem. The nonlinear system of equations is solved using a Newton procedure which provides faster convergence rates. Suitable stabilization techniques are used to extend the solution to the case of highly loaded contacts. The complexity is the same as for classical algorithms, but an improved convergence rate, a reduced size of the problem and a sparse Jacobian matrix are obtained. Thus, the computational effort, time and memory usage are considerably reduced.

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Finite Element Analysis of Large-Size Yaw Bearings with Supporting Structure in Wind Turbine

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.672-674.1550 ◽

2014 ◽

Vol 672-674 ◽

pp. 1550-1553

Author(s):

Zhen Guo Shang ◽

Zhong Chao Ma ◽

Zhen Sheng Sun

Keyword(s):

Finite Element ◽

Wind Turbine ◽

Point Contact ◽

Element Model ◽

Contact Forces ◽

Element Analysis ◽

Supporting Structure ◽

Rolling Elements ◽

Yaw Bearing ◽

Compression Springs

A procedure for obtaining the load distribution in a four point contact wind turbine yaw bearing considering the effect of the structure’s elasticity is presented. The inhomogeneous stiffness of the supporting structures creates a variation in the results obtained with a rigid model. A finite element model substituting the rolling elements with nonlinear compression springs has been built to evaluate the effect of the supporting structure elasticity on the contact forces between the rolling elements and the raceways.

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A recommendation of computation of normal streeses in single point incremental forming technology

Science and Technology Development Journal ◽

10.32508/stdj.v17i1.1279 ◽

2014 ◽

Vol 17 (1) ◽

pp. 21-28

Author(s):

Dien Khanh Le ◽

Nam Thanh Nguyen ◽

Binh Thien Nguyen

Keyword(s):

Finite Element Method ◽

Finite Element ◽

Incremental Forming ◽

Single Point ◽

Finite Element Method Simulation ◽

Recent Decade ◽

Work Piece ◽

Single Point Incremental Forming ◽

Forming Technology ◽

Element Method

Single Point Incremental Forming (SPIF) has become popular for metal sheet forming technology in industry in many advanced countries. In the recent decade, there were lots of related studies that have concentrated on this new technology by Finite Element Method as well as by empirical practice. There have had very rare studies by pure analytical theory and almost all these researches were based on the formula of ISEKI. However, we consider that this formula does not reflect yet the mechanics of destruction of the sheet work piece as well as the behavior of the sheet in reality. The main aim of this paper is to examine ISEKI’s formula and to suggest a new analytical computation of three elements of stresses at any random point on the sheet work piece. The suggested formula is carefully verified by the results of Finite Element Method simulation.

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The Study on Airborne Equipments Life Prediction Based on the Finite Element Simulation under Comprehensive Stress

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.365-366.224 ◽

2013 ◽

Vol 365-366 ◽

pp. 224-228

Author(s):

Tian Ma ◽

Chuan Ri Li ◽

Shuang Long Rong

Keyword(s):

Finite Element ◽

Finite Element Simulation ◽

Life Prediction ◽

Single Point ◽

Simulation Method ◽

Distribution Fitting ◽

Kinetic Experiment ◽

Element Simulation ◽

Vibration Stress ◽

Equipment Lifetime

To predict an airborne equipment lifetime with finite element simulation method, use ANSYS and Flothem, respectively, to analysis vibration stress and temperature stress, corrected by kinetic experiment; then import the results into the failure prediction software-CALCE PWA, set the intensity and duration of stress according to its mission profile, finally get the component failure life prediction results under comprehensive temperature and vibration stress; extract the Monte-Carlo simulation data, use the single point of failure distribution fitting, fault clustering and multipoint distribution fusion method to get the board and the whole machines lifetime and reliability prediction. The design refinement suggestion of the airborne equipment is given at the end of the conclusion.

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Finite Element Analysis of Fiber Composite Dental Bridges: The Effect of Length / Depth Ratio and Load Application Method

10.1115/imece1999-0471 ◽

1999 ◽

Author(s):

Michael D. Nowak ◽

Kim Haser ◽

A. Jon Goldberg

Keyword(s):

Finite Element Analysis ◽

Finite Element ◽

Mechanical Testing ◽

Fiber Composite ◽

Single Point ◽

Element Analysis ◽

Elastic Range ◽

Single Force ◽

Range Testing ◽

Fiber Reinforce

Abstract Work is continuing in the evaluation of orthotropic fiber reinforce composites for use in the construction of dental bridges. Finite Element Analysis (FEA) models were constructed based upon mechanical testing of end clamped specimens center loaded with a metal indenter. Various length / depth specimens were evaluated in the elastic range, with a variety of load magnitudes. Separate FEA models utilized single point loading, distributed loading, and the construction of a model indenter. Deflections at the loading point demonstrated that all models presented similar findings to those seen in mechanical testing. The similarity of results between the single loading point and the indenter FEA models suggest that either is reasonable for elastic range testing. The significantly shorter CPU run times for the single force models suggest that this may be the best means by which to model orthotropic fiber reinforced dental composites in the elastic range.

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A Node Embedding-Based Influential Spreaders Identification Approach

Mathematics ◽

10.3390/math8091554 ◽

2020 ◽

Vol 8 (9) ◽

pp. 1554

Author(s):

Dongming Chen ◽

Panpan Du ◽

Bo Fang ◽

Dongqi Wang ◽

Xinyu Huang

Keyword(s):

Social Influence ◽

Vector Space ◽

Single Point ◽

Point Contact ◽

Representation Learning ◽

Influence Maximization ◽

Maximization Problem ◽

Data Sets ◽

Full Contact ◽

The Social

Node embedding is a representation learning technique that maps network nodes into lower-dimensional vector space. Embedding nodes into vector space can benefit network analysis tasks, such as community detection, link prediction, and influential node identification, in both calculation and richer application scope. In this paper, we propose a two-step node embedding-based solution for the social influence maximization problem (IMP). The solution employs a revised network-embedding algorithm to map input nodes into vector space in the first step. In the second step, the solution clusters the vector space nodes into subgroups and chooses the subgroups’ centers to be the influential spreaders. The proposed approach is a simple but effective IMP solution because it takes both the social reinforcement and homophily characteristics of the social network into consideration in node embedding and seed spreaders selection operation separately. The information propagation simulation experiment of single-point contact susceptible-infected-recovered (SIR) and full-contact SIR models on six different types of real network data sets proved that the proposed social influence maximization (SIM) solution exhibits significant propagation capability.

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Effect of Rotation Speed on Electric Damage of Copper Tribo/Electric Rolling Pairs under Lubricated Single-Point Contact

MATERIALS TRANSACTIONS ◽

10.2320/matertrans.mt-m2019214 ◽

2020 ◽

Vol 61 (1) ◽

pp. 111-118

Author(s):

Zili Liu ◽

Chenfei Song ◽

Jiawei Li ◽

Xinbin Hou ◽

Li Wang ◽

...

Keyword(s):

Rotation Speed ◽

Single Point ◽

Point Contact

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Refined Vehicle-Bridge Interaction Analysis Using Incompatible Solid Finite Element for Evaluating Stresses and Impact Factors

Advances in Civil Engineering ◽

10.1155/2020/7032460 ◽

2020 ◽

Vol 2020 ◽

pp. 1-15

Author(s):

Qing Xie ◽

Wanshui Han ◽

Yangguang Yuan

Keyword(s):

Finite Element ◽

Computational Efficiency ◽

Interaction Analysis ◽

Computational Cost ◽

Point Contact ◽

Time History ◽

Analysis Method ◽

Heavy Vehicles ◽

Solid Element ◽

Bridge Responses

The vehicle-bridge interaction can induce bridge vibration and consequently fatigue, durability deterioration, local damage, and even collapse of bridge structure. In this paper, a solid vehicle-bridge interaction (VBI) analysis method is developed to provide refined analysis on the bridge responses including displacement and local stress under vehicle loads. The incompatible solid finite element (FE) is introduced to model the bridge, where the element shear locking is alleviated by incompatible displacement modes without sacrificing the computational efficiency. Benchmark example shows the incompatible solid element has superior computational efficiency compared to the conventional solid element. By virtue of the mass-spring-damper vehicle model, the interaction between vehicle and bridge is simulated with point-to-point contact assumption and the coupled dynamic equations are solved via nonlinear iteration. A case study on a simply supported T-girder bridge is conducted to validate the developed solid VBI analysis method and then the dynamic impact factor (DIF) of the bridge is evaluated based on the computed stress results and compared to code values. Results show that the solid VBI analysis method yields more accurate time-history bridge responses including displacement and stress under moving vehicles than the grillage method despite higher computational cost. Particularly, it can simulate realistic stress distribution and concentration along any concerned sections as well as in local components, which can provide detail information on the bridge behavior under dynamic loads. On the other hand, the DIF based on the computed stress result generally agrees well with the code values except for heavy vehicles where the stress-based DIF is slightly higher than the value in Chinese code while lower than that of AASHTO, suggesting the value specified by Chinese code may underestimate the DIF of heavy vehicles in certain circumstances to which more attention should be paid.

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