Finite element analysis of knee and ankle joint during gait based on motion analysis

Park, Sangbaek,Lee, Seungju,Yoon, Jeongro,Chae, Soo-Won Elsevier 2019 Medical engineering & physics Vol.63 No.-

<P><B>Abstract</B></P> <P>Contact pressures in the articular cartilage during gait affect injuries and the degenerative arthritis of knee and ankle joints. However, only contact forces at the knee and ankle joints during gait can be estimated by using a rigid body dynamic model. The contact pressure distribution can be obtained quantitatively for a static posture by using finite element (FE) analysis in most cases. The purpose of this study is to develop a new method to obtain the contact pressure distribution at the knee and ankle joints during gait by integrating FE analysis with rigid body dynamic analysis. In this method, a reference FE model of the lower extremity is constructed first and is then transformed to each stance phase of the gait obtained from dynamic analysis by using homogeneous transformation. The muscle forces and ground reaction force (GRF) during gait obtained from the dynamic analysis were used as loading conditions for FE analysis. Finally, the contact pressure distribution at the tibia plateau cartilage and talus cartilage were estimated at the 1st peak, mid-stance, and the 2nd peak at the same time. The present method can provide the contact pressure distribution at the knee and ankle joints over the entire gait.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A new method that integrates FE analysis with rigid body dynamic analysis is proposed. </LI> <LI> Interface program with self-written codes is developed to apply the results of motion analysis to the FE analysis. </LI> <LI> Coordinate system matching OpenSim model and FE model is performed to transform the FE model. </LI> <LI> Contact pressure distribution at the knee and ankle joints can be obtained according to the desired stance phase. </LI> </UL> </P>

Contact Tracking Development Trend Using Bibliometric Analysis

Chaoqun Li,Zhigang Chen,Tongrui Yu,Xinxia Song 한국정보처리학회 2022 Journal of information processing systems Vol.18 No.3

The new crown pneumonia (COVID-19) has become a global epidemic. The disease has spread to mostcountries and poses a challenge to the healthcare system. Contact tracing technology is an effective way forpublic health to deal with diseases. Many experts have studied traditional contact tracing and developed digitalcontact tracking. In order to better understand the field of contact tracking, it is necessary to analyze thedevelopment of contact tracking in the field of computer science by bibliometrics. The purpose of this researchis to use literature statistics and topic analysis to characterize the research literature of contact tracking in thefield of computer science, to gain an in-depth understanding of the literature development status of contacttracking and the trend of hot topics over the past decade. In order to achieve the aforementioned goals, weconducted a bibliometric study in this paper. The study uses data collected from the Scopus database. Whichcontains more than 10,000 articles, including more than 2,000 in the field of computer science. For populartrends, we use VOSviewer for visual analysis. The number of contact tracking documents published annuallyin the computer field is increasing. At present, there are 200 to 300 papers published in the field of computerscience each year, and the number of uncited papers is relatively small. Through the visual analysis of the paper,we found that the hot topic of contact tracking has changed from the past “mathematical model,” “biologicalmodel,” and “algorithm” to the current “digital contact tracking,” “privacy,” and “mobile application” and othertopics. Contact tracking is currently a hot research topic. By selecting the most cited papers, we can displayhigh-quality literature in contact tracking and characterize the development trend of the entire field throughtopic analysis. This is useful for students and researchers new to field of contact tracking ai well as forpresenting our results to other subjects. Especially when comprehensive research cannot be conducted due totime constraints or lack of precise research questions, our research analysis can provide value for it.

초고압 단로기 접점의 단락전류 통전성능 평가기술 개발

吳年浩(Yeon-Ho Oh),宋基東(Ki-Dong Song),鄭鎭敎(Jin-Kyo Chong) 대한전기학회 2008 전기학회논문지 Vol.57 No.1

Extra-high voltage(EHV) disconnecting switch(DS) consists of the electrical contacts and mechanical parts which actuate the contacts. When the short-circuit condition occurs, a large amount of current flows through the electrical contact in disconnecting switches and this causes considerable temperature rise due to Joule heating. If the temperature rise is higher than the melting point of contact material, the DS contact becomes melting and cannot be usable anymore. For this reason, the analysis for capability of carrying short-circuit current in DS contacts must be performed at a design stage. Here, we proposed a numerical technique for evaluating the capability of carrying short-circuit current at electrical contacts in EHV DS. In this numerical approach, the mechanical and thermal analyses were simulated to check the capability of carrying short-circuit current. First, the applied pressure at contact parts was analyzed considering the mechanical properties, and then contact resistance was calculated by an empirical equation. Finally, thermal analysis was performed with resistance variation at electrical contacts. To verify these numerical results, the distributions of temperature in DS were experimentally measured and compared with each other. The results from experiments were agreed well with those from the proposed numerical simulations.

차륜/레일의 구름접촉을 위한 유한요소모델 및 접촉피로 수명평가

서정원,전현규,배영훈,여인호 한국도시철도학회 2022 한국도시철도학회논문집 Vol.10 No.1

Fatigue damage on the rail surface is caused by repeated rolling contact between the wheel and the rail. Such damage to the rail surface affects ride comfort, noise and driving safety. If proper maintenance is not performed, the rail may break and cause a major accident. It is important to evaluate and predict fatigue damage caused by rolling contact for safety and maintenance of rail. In this paper, a procedure and a finite element model were developed to evaluate the rolling contact fatigue damage of rail. A submodel technique was used to accurately evaluate the repeated rolling contact and the elasto-plastic behavior of the material. Since the surface of the rail undergoes plastic deformation in rolling contact with the wheel, the shape of the contact surface changes, so the contact pressure was obtained through elasto-plastic analysis. From the rolling contact fatigue life evaluation, it was found that cracks occurred at a depth of 2.4 mm from the rail surface, parallel to the surface and almost perpendicular to the rolling direction. 레일 표면의 피로손상은 차륜과 레일의 반복적인 구름접촉에 의해서 발생한다. 이러한 손상은 승차감, 소음 및 주행안전성 등에 영향을 미친다. 만일 적합한 유지보수가 수행되지 않으면 레일의 파단이 발생하여 대형사고를 일으킨다. 레일의 안전성 확보와 유지보수를 위해서는 구름접촉에 의해서 발생하는 피로손상을 평가하고 예측하는 것이 중요하다. 본 논문에서는 레일의 구름접촉피로손상을 평가하기 위한 절차 및 유한요소모델을 개발하였다. 반복적인 구름접촉과 재료의 탄소성 거동을 정확하게 평가하기 위하여 서브모델 기법을 사용하였다. 레일의 표면은 차륜과의 구름접촉으로소성변형이 발생하고, 레일의 접촉면 형상이 변화하므로 탄소성 해석을 통하여 접촉압력을 구하였다. 접촉피로수명평가로부터, 균열은 레일 표면에서 2.4mm 떨어진 깊이에서 표면과 수평이고, 구름방향의 거의 직각인 방향로 발생함을 알 수 있었다.

Two-dimensional frictionless large deformation contact problems using isogeometric analysis and Nitsche’s method

Zhao Gang,Zhang Ran,Wang Wei,Du Xiaoxiao 한국CDE학회 2022 Journal of computational design and engineering Vol.9 No.1

The simulation of large deformation contact problems has been a tough subject due to the existence of multiple nonlinearities, including geometric nonlinearity and contact interface nonlinearity. In this paper, we develop a novel method to compute the large deformation of 2D frictionless contact by employing Nitsche-based isogeometric analysis. The enforcement of contact constraints as one of the main issues in contact simulation is implemented by using Nitsche’s method, and the node-to-segment scheme is applied to the contact interface discretization. We detailedly derive the discrete formulations for 2D large deformation frictionless contact where NURBS is used for geometrical modeling and the Neo-Hookean hyperelastic materials are applied to describe the deformation of the model. The collocation method with Greville points is employed to integrate the contact interface and the classical Legendre–Gauss quadrature rule is used for contact bodies’ integration. The Lagrange multiplier method and penalty method are also implemented for comparison with Nitsche’s method. Several examples are investigated, and the obtained results are compared with that from commercial software ABAQUS to verify the effectiveness and accuracy of the Nitsche-based isogeometric analysis.

응착 완전 접촉 문제에서 접촉면 미끄럼 현상에 관한 고찰

김형규 한국트라이볼로지학회 2020 한국트라이볼로지학회지 (Tribol. Lubr.) Vol.36 No.3

This paper is within the framework of an adhered complete contact problem wherein the contact between a half plane and sharp edged indenter, both of which are elastic in character, is constituted. The eigensolutions of the contact shear and normal stresses, σrq and σq, respectively, are evaluated via asymptotic analysis. The ratio of σrq/σqq is investigated and compared with the coefficient of friction, μ, of the contact surface to observe the propensity to slip on the contact surface. Interestingly, there exists a region of |σrθ/σθθ| ≥ |μ|. Thus, slipping can occur, although the problem is solved under the condition of an adhered contact without slipping. Given that a tribological failure potentially occurs at the slipping region, it is important to determine the size of the slipping region. This aspect is also factored in the paper. A simple example of the adhered contact between two elastically dissimilar squares is considered. Finite element analysis is used to evaluate generalized stress intensity factors. Furthermore, it is repeatedly observed that slipping occurs on the contact surface although the size of it is extremely small compared with that of the contacting squares. Therefore, as a contribution to the field of contact mechanics, this problem must be further explained logically.

Mathematical Model and Tooth Contact Analysis of an Internal Helical Gear Pair with Selectable Contact Path

Shuai Peng,Bingkui Chen,Dong Liang,Lu-he Zhang,Si-ling Qin 한국정밀공학회 2018 International Journal of Precision Engineering and Vol.19 No.6

An internal helical gear pair with point contact pattern based on the space meshing theory is proposed which consists of an involute internal gear and a pinion with quadratic curve profile. Particularly, the contact path of the tooth surface is selectable, which can inherit the characteristic of the surface. Moreover, this type of internal gear pair has lower sensitivity to assembly errors. The generation principle and mathematical model is presented. The motion simulation and adaptability to center distance error of the internal gear pair are discussed. The gear pair is manufactured. Based on the mathematical model and tooth contact analysis (TCA) method, the locations of contact points and kinematic errors are determined under different center distance variation and axial misalignments. The simulated results reveal that the locations of contact points of the gear and pinion change under assembly errors. Little kinematic error occurs under axial misalignment. No edge contact occurs under any assembly error condition. Experiment study is performed and the result is consistent with the theoretical analysis.

A novel method for longitudinal modification and tooth contact analysis of non-circular cylindrical gears

Dawei Li,Yongping Liu,Jun Gong,Yongqiao Wei,Gang Zhao 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.12

The traditional geometry of non-circular cylindrical gears provides a contact line between tooth surfaces. In a misaligned non-circular cylindrical gear drive, causing edge contacts that result in noise and vibration. The point contact of the tooth surface is achieved by modification of the driving gear in the longitudinal direction, in order to reduce the sensitivity of tooth surface contact to installation errors. The proposed longitudinal modification method is based on the application of a grinding worm by controlling the center distance of non-circular cylindrical gear and worm. Based on the gear meshing principle, a mathematical model of the tooth surfaces of non-circular cylindrical gears is established, and a parametric tooth surface equation with a unified expression is obtained. Tooth contact analysis (TCA) of non-circular cylindrical gears shows that the contact path and contact area on the tooth surface are shifted with the change of installation error, but still distributed in the middle of the tooth surface without creating edge contact. The transmission error is increased with the growth of installation error. Tooth modification in a longitudinal direction has an obvious improvement effect on the bad tooth contact condition, but too large a tooth modification parameter will make the tooth surface load distribution concentrated in a smaller area, which results in the decrease of gear load capacity.

PIP 개스킷의 3D Sealing 해석과 평가방법에 관한 연구

강병권(Byoungkwon Kang),이병하(Byung-ha Lee),윤재원(Jaewon Youn) 한국자동차공학회 2015 한국자동차공학회 학술대회 및 전시회 Vol.2015 No.11

Types of elastomeric seals include PIP (Press in Place) gaskets, O-rings and edged bonded gasket with metal carrier. This study focused on PIP gasket. In general, for development or validation of PIP gasket, minimum sealing pressure, maximum nominal principal strain and minimum seal contact width are delivered at operating temperatures through 2D Cross-Section analysis. Then, 3D system structural analysis is performed with load-deflection curve that is from 2D Cross-Section analysis. However, in case of some specific geometries, the approach of 2D Cross-Section analysis would be inappropriate. For example, a cam cover including mechanical vacuum pump has a half-moon contact area at which the gasket profile and standoff value are changed. In this case, it is difficult to evaluate the gasket sealing performance with 2D Cross-Section analyses. In fact, there were some leaks and tear issues in the validation test even though all analysis results with a common method met the internal target. In this study, we performed 3D gasket sealing analysis for PIP gasket and proposed how to evaluate the analysis results.

길들이기 과정을 고려한 변속기용 기어의 접촉피로 수명 예측

문길환(Kilhwan Moon),이석기(Sukgi Lee),이상돈(Sangdon Lee),조용주(Yongjoo Cho) 한국자동차공학회 2006 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-

The contact fatigue life analysis of transmission gear considering run-in process is presented in this paper. The effect of surface roughness change can be calculated by this analysis. To apply "Run-in" process to the contact fatigue life prediction, rolling test results were used. Computational method and the theoretical basis are also discussed. Contact stresses are obtained by contact analysis of a semi-infinite solid based on the use of influence functions; the subsurface stress field is obtained using rectangular patch solutions. Mesoscopic multiaxial fatigue criterion which can yield satisfactory results for nonproportional loading is then applied to predict fatigue damage. Suitable counting method and damage rule were used to calculate the fatigue life of random loading caused by rough surface. As a result of analysis the relationship between the life and the variable roughness is calculated.