scholarly journals Infinite Element Static-Dynamic Unified Artificial Boundary

2018 ◽  
Vol 2018 ◽  
pp. 1-14 ◽  
Author(s):  
Zhiqiang Song ◽  
Fei Wang ◽  
Yujie Liu ◽  
Chenhui Su
Keyword(s):  
Reaction Force ◽  
Tangential Direction ◽  
Dynamic Effects ◽  
Artificial Boundary ◽  
Infinite Element ◽  
Dynamic Synthesis ◽  
Dynamic Boundary ◽  
Static Calculation ◽  
Force Calculation ◽  
External Wave

The method, which obtains a static-dynamic comprehensive effect from superposing static and dynamic effects, is inapplicable to large deformation and nonlinear elastic problems under strong earthquake action. The static and dynamic effects must be analyzed in a unified way. These effects involve a static-dynamic boundary transformation problem or a static-dynamic boundary unified problem. The static-dynamic boundary conversion method is tedious. If the node restraint reaction force caused by a static boundary condition is not applied, then the model is not balanced at zero moment, and the calculation result is distorted. The static numerical solution error is large when the structure possesses tangential static force in a viscoelastic static-dynamic unified boundary. This paper proposed a new static-dynamic unified artificial boundary based on an infinite element in ABAQUS to solve static-dynamic synthesis effects conveniently and accurately. The static and dynamic mapping theories of infinite elements were introduced. The characteristic of the infinite element, which has zero displacement at faraway infinity, was discussed in theory. The equivalent nodal force calculation formula of infinite element unified boundary was deduced from an external wave input. A calculation and application program of equivalent nodal forces was developed using the Python language to complete external wave inputting. This new method does not require a static and dynamic boundary transformation and import of stress field and constraint counterforce of boundary nodes. The static calculation precision of the infinite element unified boundary is more improved than the viscoelastic static-dynamic unified boundary, especially when the static load is in the tangential direction. In addition, the foundation simulation range of finite field can be significantly reduced given the utilization of the infinite element static dynamic unified boundary. The preciseness of static calculation and dynamic calculation and static-dynamic comprehensive analysis are unaffected.

scholarly journals Dynamic analysis of a ten-link tooth-lever differential transmission

2021 ◽  
Vol 939 (1) ◽  
pp. 012024
Author(s):  
A Abdukarimov ◽  
I Saidakulov
Keyword(s):  
High Speed ◽  
Reaction Force ◽  
Transmission Mechanism ◽  
Force Analysis ◽  
Axis Of Rotation ◽  
Processed Material ◽  
Differential Transmission ◽  
External Forces ◽  
Force Calculation ◽  
Force Characteristics

Abstract This article discusses the dynamics of a ten-link tooth-lever differential transmission mechanism. The force analysis of the transmission mechanism is given in order to find the dependence for determining the reaction in kinematic pairs and the balancing moment of the pair of forces and to show some features of the tooth-lever transmission mechanism. The force calculation was carried out taking into account the accelerated movement of links since their acceleration in modern high-speed machines is very significant. To obtain a more accurate concept of the external forces and moments loading the transmission mechanism in the accelerated movement of the links, the dynamics of the transient process of roller technological machines was considered. Cases of feeding the processed material were considered both from the side of the intermediate gears and from the side opposite to the parasitic gears. Dependencies were obtained to determine the force characteristics of this mechanism. Cases of pressure unloading and overloading on the processed material from the side of the free shaft, depending on the location of the transmission mechanism are shown. The dependence of the reaction force of intermediate gears on their own axes of rotation on the angle between the levers is shown. With an increase in the angle between the levers, the reaction of the intermediate gears on the axis of rotation increases.

scholarly journals Development of a Knee Joint CT-FEM Model in Load Response of the Stance Phase During Walking Using Muscle Exertion, Motion Analysis, and Ground Reaction Force Data

Medicina ◽  
2020 ◽  
Vol 56 (2) ◽  
pp. 56
Author(s):  
Kunihiro Watanabe ◽  
Hirotaka Mutsuzaki ◽  
Takashi Fukaya ◽  
Toshiyuki Aoyama ◽  
Syuichi Nakajima ◽  
...  
Keyword(s):  
Finite Element ◽  
Knee Joint ◽  
Ground Reaction Force ◽  
Reaction Force ◽  
Equivalent Stress ◽  
Element Model ◽  
Calculation Model ◽  
Quantitative Ct ◽  
Load Response ◽  
Force Calculation

Background and objectives: There are no reports on articular stress distribution during walking based on any computed tomography (CT)-finite element model (CT-FEM). This study aimed to develop a calculation model of the load response (LR) phase, the most burdensome phase on the knee, during walking using the finite element method of quantitative CT images. Materials and Methods: The right knee of a 43-year-old man who had no history of osteoarthritis or surgeries of the knee was examined. An image of the knee was obtained using CT and the extension position image was converted to the flexion angle image in the LR phase. The bone was composed of heterogeneous materials. The ligaments were made of truss elements; therefore, they do not generate strain during expansion or contraction and do not affect the reaction force or pressure. The construction of the knee joint included material properties of the ligament, cartilage, and meniscus. The extensor and flexor muscles were calculated and set as the muscle exercise tension around the knee joint. Ground reaction force was vertically applied to suppress the rotation of the knee, and the thigh was restrained. Results: An FEM was constructed using a motion analyzer, floor reaction force meter, and muscle tractive force calculation. In a normal knee, the equivalent stress and joint contact reaction force in the LR phase were distributed over a wide area on the inner upper surface of the femur and tibia. Conclusions: We developed a calculation model in the LR phase of the knee joint during walking using a CT-FEM. Methods to evaluate the heteromorphic risk, mechanisms of transformation, prevention of knee osteoarthritis, and treatment may be developed using this model.

Numerical Analyses for Layered Foundation by Coupling Finite and Axis-Radiate Infinite Elements

2011 ◽  
Vol 90-93 ◽  
pp. 359-364
Author(s):  
Hong Yang Xie ◽  
Huan Yang ◽  
Jin Quan Yin
Keyword(s):  
Numerical Calculation ◽  
Good Accuracy ◽  
Elastic Recovery ◽  
Rigid Base ◽  
Artificial Boundary ◽  
Element Mesh ◽  
Mapping Functions ◽  
Infinite Element ◽  
Infinite Elements ◽  
Recovery Capacity

The model of the axis-radiate infinite element is developed for simulation of the infinite layered foundation underlain by a rigid base. Within the infinite element, the coordinate and displacement of any point are expressed by those of the nodes located on the artificial boundary, and concise mapping functions can easily express the attenuation character of the displacement field. By coupling finite and infinite elements, the elastic recovery capacity and radiation damping of the infinite layered foundation are simulated. In the numerical calculation, the infinite element mesh is performed only on the artificial boundary. Compared to FEM, the present approach needs less nodes and elements, and shows good accuracy and efficiency.

Analysis of Dynamic Characteristics of Pile-Soil Coupling Effect in Consideration of Large Span Cable-Stayed Bridge

2014 ◽  
Vol 501-504 ◽  
pp. 1270-1273
Author(s):  
Wen Yuan Chen
Keyword(s):  
Axial Force ◽  
Soil Structure ◽  
Coupling Effect ◽  
Reaction Force ◽  
Bending Moment ◽  
Internal Force ◽  
Cable Stayed Bridge ◽  
Long Span ◽  
Pile Cap ◽  
Force Calculation

Using the viscouselastic artificial boundary, three conditions of long-span cable-stayed bridge are analyzed,such as pile cap consolidation, pile - structure and pile soil structure interaction. Natural frequency of bridge of pile - soil - structure coupling becomes small and cycle becomes long. The pile bottom reaction force decreased obviously, at the same time, the axial force , bending moment, axial force of cable, tower of axial force and bending moment is also reduced significantly. Cable-stayed bridge is a special flexible structure, so, static internal force calculation in the tower bottom consolidation pattern is safe, but the value is too large.

scholarly journals Calculation of the Influence Zone for Planetary Sampling Based on DEM Simulation

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Qian Li ◽  
Junping Li ◽  
Lanlan Xie
Keyword(s):  
Soil Mechanics ◽  
Reaction Force ◽  
Lunar Soil ◽  
Sampling Device ◽  
Influence Zone ◽  
Dem Simulation ◽  
Related Research ◽  
Physical Experiments ◽  
Device Structures ◽  
Force Calculation

In the design of planetary sampling devices, calculating the reaction force acting on the sampling devices is crucial. According to related research, the influence zone caused by sampling plays an important role in calculating the reaction force. A new method for estimating the range of the influence zone based on 3D DEM simulation is discussed in this paper. Taking lunar soil as an example, first, via validation of physical experiments, the DEM lunar soil simulant was proven to have mechanical properties similar to those of real lunar soil. Second, stress was selected as an indicator to identify the influence zone by computing the match percentage via a comparison between classical soil mechanics and DEM simulation. Using the proposed calculation method, it can be observed that the trend of change of influence zone at different sampling moments showed similar to the change of reaction force. Calculation of the influence zone can be used to analyze the reaction force of different gravity environments, sampling device structures, and motions.

scholarly journals DESIGN OF A CONTROLLER FOR IDEAL POSITIONING SERVOSYSTEM

2019 ◽  
pp. 134-140
Author(s):  
Lubica Mikova
Keyword(s):  
Pid Controller ◽  
High Speed ◽  
Initial Conditions ◽  
Reaction Force ◽  
Point Of View ◽  
Integration Constant ◽  
Engineering Practice ◽  
Theoretical Point ◽  
Dynamic Effects ◽  
Low Pass

Urgency of the research. In advanced mechatronics, motion systems are the key technology, since mechanical systems such as Microelectronics manufacturing equipments are often required for high speed and accuracy. As a result, the increasing influence of the dynamics of the mechanical system on the quality of the position servosystem is noticeable. One of the important dynamic effects is the dynamics of the mechatronic system's vibroisolation, which arises as a result of the reaction force generated by the action variable. Target setting. The aim of the paper was to design a PID controller for an ideal positioning servosystem. Ideal positioning servosystem consists of a one mass which is actuated by the Fservo force. Actual scientific researches and issues analysis. In modern controllers, in the correction error value, classic feedback combines with forwarding feedback. The forward control is based on the fact that if the model of the mechanical actuator is known and all the initial conditions are zero, the desired position can be reached without the use of feedback. Uninvestigated parts of general matters defining. From a theoretical point of view, it has been devoted to ideal positioning servosystem for quite a long time, but the results achieved are rarely used in practice. One of the reasons is their theoretical focus, using complex mathematics, and as a result there is a great gap between theory and engineering practice. The research objective. Design of PID controller is based on equation for crossover frequencies, which allows to determine the derivative and integration constant of a PID controller for a given bandwidth. The statement of basic materials. The most important dynamic effects that impact the properties of actuators are actuator flexibility, flexibility of system limited mass and rigidity of the stationary part of the system. From the equation for the eigenfrequency ωDP of the low-pass second order filter is determined. Finally, the specific gain P is determined to suit the amplitude and phase margin. This completes the design of the ideal positioning servosystem. Conclusions. PID controller for an ideal positioning servosystem is design based on equation for crossover frequencies, which allows to determine the derivative and integration constant of a PID controller for a given bandwidth.

Application of Three-Moment Equation in Rudder Stock's Force Calculation

2013 ◽  
Vol 347-350 ◽  
pp. 3435-3439
Author(s):  
Bin Can Zhang
Keyword(s):  
Mechanical Model ◽  
Reaction Force ◽  
Bending Moment ◽  
Moment Equation ◽  
Strength Theory ◽  
Check Calculation ◽  
Conventional Methods ◽  
Force Calculation

The mechanical model of the rudder stock is established. The rudder stock can be simplified into a statically indeterminate beam. The reaction force from the support, torque and bending moment within the length of the rudder stock can be solved using three-moment equation. The stress in the profile of the stock is checked using the fourth strength theory. The calculation is directly carried out based on Ship Specification of Classification and Shipbuilding. Compared with the conventional methods, the results show that three-moment equation is correct and available in check calculation.

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