A Global Simulation Model for Hermetic Reciprocating Compressors

1991 ◽  
Vol 113 (3) ◽  
pp. 395-400 ◽  
Author(s):  
M. A. de los Santos ◽  
S. Cardona ◽  
J. Sa´nchez-Reyes
Keyword(s):  
Theoretical Model ◽  
Simulation Model ◽  
Modal Analysis ◽  
Degrees Of Freedom ◽  
Element Model ◽  
Discrete Element Model ◽  
Lagrange Equations ◽  
The Impact ◽  
Three Degrees Of Freedom ◽  
Elastic Elements

This article presents a simulation model for reciprocating hermetic compressors. The acoustical behavior of both admission and discharge circuits is analyzed by invoking the discrete element model. Cavities are considered as elastic elements and ducts as rigid elements with inertia according to this model. Reed valves are modeled as systems of three degrees of freedom, and are studied by using modal analysis. The percussive version of Lagrange equations is used to describe the impact between valves and stops or seats. Results from the theoretical model are checked with those experimentally obtained for a real compressor.

Fractality of Simulated Fracture

2009 ◽  
Vol 409 ◽  
pp. 154-160 ◽  
Author(s):  
Petr Frantík ◽  
Zbyněk Keršner ◽  
Václav Veselý ◽  
Ladislav Řoutil
Keyword(s):  
Numerical Model ◽  
Elastic Plate ◽  
Model Simulation ◽  
Element Model ◽  
The Other ◽  
Particle Model ◽  
Discrete Element Model ◽  
Fractal Nature ◽  
Discrete Elements ◽  
The Impact

The paper is focussed on numerical simulations of the fracture of a quasi-brittle specimen due to its impact onto a fixed rigid elastic plate. The failure of the specimen after the impact is modelled in two ways based on the physical discretization of continuum: via physical discrete elements and pseudo-particles. Advantages and drawbacks of both used methods are discussed. The size distribution of the fragments of the broken specimen resulting from physical discrete element model simulation follows a power law, which indicates the ability of the numerical model to identify the fractal nature of the fracture. The pseudo-particle model, on the other side, can successfully predict the kinematics of the fragments of the specimen under impact failure.

KINEMATICS FEATURES OF HAMMER PERFORATED TILLAGE ROLL

2020 ◽  
pp. 13-19
Author(s):  
I. А. Sharonov ◽  
◽  
Yu. М. Isaev ◽  
V. I. Kurdyumov ◽  
◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Soil Layer ◽  
Point Of View ◽  
Lagrange Equations ◽  
Middle Volga Region ◽  
Perforated Cylinder ◽  
Winter Crops ◽  
Combined Impact ◽  
The Impact

The task of improving the quality of agricultural tools by improving the technological processes of their functioning, taking into account the kinematic features of the combined impact of working elements of tools on the soil environment is important from a scientific and technical point of view. To form the required structure and density of the soil layer at the depth of sowing, a hammer perforated tillage roller (HPTR) has been developed. The study aim is to improve the quality of post-sowing compaction and structuring of the soil layer in the seed location zone based on the development of an innovative design of HPTR that combines different effects on the treated environment. The object of research is the kinematic mode of operation of the HPTR, equipped with cylindrical hammers installed at the ends of the rod, which, in turn, are radially and pivotally installed on the axis of the gunFeature of offered HPTR is the excitation of hammer vibrations, which changes the kinematic parameters of the tillage tool as a whole. Lagrange equations of the second kind are used to describe the process of HPTR operation, which is represented as a system of material objects with several degrees of freedom. The conducted studies revealed the periodic nature of changes in the strength of the impact of HPTR on the soil. The obtained equations allow us to determine the features of the HPTR movement at different masses of a hollow perforated cylinder and cylindrical hammers. This is of great importance for increasing the efficiency of soil bolster destruction and creating the soil structure recommended for winter crops sown in the Middle Volga region.

Establishment and verification of theoretical model for forming design of balanced curved rubber hose

2020 ◽  
pp. 096739112092592
Author(s):  
Gao Hua ◽  
Shuai Changgeng ◽  
Xu Guomin
Keyword(s):  
Theoretical Model ◽  
Simulation Model ◽  
Structural Parameters ◽  
Axial Direction ◽  
Element Model ◽  
Rubber Hose ◽  
Balance Performance ◽  
Equilibrium Angle ◽  
Calculation Results ◽  
Thin Shell Theory

This article focuses on the establishment of theoretical model for the formation of balanced curved rubber hose under pressure. According to the rotation angle of the cord along the axial direction in the curved rubber hose is the same as that in the straight hose before forming, the theoretical model of the straight hose length was established. Then based on the thin shell theory without considering bending moments and shear force, and considering the deformation characteristics of the rope structure and the mechanical equilibrium angle of the hose, the theoretical model of the balance performance was established. According to the theoretical model, the influence of structural parameters of curved hose on the length of the straight hose and the balance performance of hose was studied. Eventually, the finite element model was established to simulate the deformation process of the curved hose. Based on the calculation results of the theoretical and simulation model, the experiment of forming and balance performance of the curved hose was carried out. The experimental results are in good agreement with the theoretical and simulation model.

DYNAMIC PROPERTIES OF THE ELECTROMECHANICAL SYSTEM DAMPED BY AN IMPACT ELEMENT WITH SOFT STOPS

2014 ◽  
Vol 06 (02) ◽  
pp. 1450016 ◽  
Author(s):  
MAREK LAMPART ◽  
JAROSLAV ZAPOMĚL
Keyword(s):  
Degrees Of Freedom ◽  
Dynamic Properties ◽  
Electric Circuit ◽  
Response Characteristic ◽  
Electromechanical System ◽  
Frequency Response Characteristic ◽  
Impact Element ◽  
The Impact ◽  
The Mathematical Model ◽  
Three Degrees Of Freedom

The main aim of this paper is to focus on analysis of the dynamic properties of the electromechanical system with an impact element. This model is constructed with three degrees of freedom in the mechanical oscillating part, two translational and one rotational, and is completed with an electric circuit. The mathematical model of the system is represented by three mutually coupled second-order ordinary differential equations. Here, the most important nonlinearities are: stiffness of the support spring elements and internal impacts. Several important results were obtained by means of computational simulations. The impacts considerably increase the number of resonance peaks of the frequency response characteristic. Character of the system motion strongly depends on the width of clearances between the impact body and the rotor frame and changes from simple periodic to close to chaotic or to periodic with a large number of ultraharmonic components. For a suitably chosen system parameters, a significant damping effect of the impact element was observed.

scholarly journals The impacting cantilever: modal non-convergence and the importance of stiffness matching

2013 ◽  
Vol 371 (1993) ◽  
pp. 20120434 ◽  
Author(s):  
John Melcher ◽  
Alan R. Champneys ◽  
David J. Wagg
Keyword(s):  
Modal Analysis ◽  
Degrees Of Freedom ◽  
Applied Mathematics ◽  
Point Of View ◽  
Higher Order Modes ◽  
Intermittent Contact ◽  
Bilinear Formulation ◽  
Modal Truncation ◽  
The Impact ◽  
Impact Models

The problem of an Euler–Bernoulli cantilever beam whose free end impacts with a point constraint is revisited from the point of view of modal analysis. It is shown that there is non-uniqueness of consistent impact laws for a given modal truncation. Moreover, taking an N -mode compliant, bilinear formulation and passing to the rigid limit leads to a sequence of impact models that does not converge as . The dynamics of such truncated models are studied numerically and found to give rise to quite different dynamics depending on the number of degrees of freedom taken. The simulations are compared with results from simple experiments that show a propensity for multiple-tap dynamics, in which higher-order modes lead to rapidly cycling intermittent contact. The conclusion reached is that, to derive an accurate model, one needs to avoid the impact limit altogether, and take sufficiently many modes in the formulation to match the actual stiffness of the constraining stop. mechanical engineering, applied mathematics

scholarly journals THE FORMATION OF PROFESSIONAL TALENT IN DETERMINATION WITH SEMANTIC ATTITUDE TO INNOVATIONS UNDER THE INFLUENCE OF VARIOUS DEGREES OF FREEDOM IN ACTIVITY

2020 ◽  
Vol 17 (4) ◽  
pp. 91-101
Author(s):  
T.N. Soboleva ◽  
Keyword(s):  
Empirical Data ◽  
Degrees Of Freedom ◽  
The Other ◽  
Psychological Analysis ◽  
Other Hand ◽  
Professional Talent ◽  
The One ◽  
The Impact ◽  
Three Degrees Of Freedom

The article is devoted to the poorly studied problem of the formation of talent in the conditions of different degrees of freedom in activity and the impact on that formation of a person’s conservative and innovative semantic attitudes towards the introduction of new equipment. The main objective of the study is to describe how the conditions of different degrees of freedom in the activity are refracted with internal conditions, which are conservative and innovative semantic attitudes and various talent structures. The study was conducted on a sample of 54 qualified railway drivers using a specialized simulator which allows to simulate three degrees of freedom in the activity. The psychological analysis of the activity revealed seven abilities ensuring the implementation of the activity. Based on empirical data, the article shows that low, medium and high degrees of freedom in activity are manifested in different degrees of productivity. Conservative and innovative semantic attitudes to the introduction of new equipment do not have a significant effect on the productivity of the activity in the conditions of different degrees of freedom. Along with this, depending on the conservative and innovative semantic attitudes, different structures of talent in terms of composition and degree of integration under the conditions of different degrees of freedom in the activity are formed. On the one hand, conservative and innovative semantic attitudes act as internal determinants; on the other hand, low, medium and high degrees of freedom in the activity act as external determinants of the formation of various talent structures.

A Simple Spring-Loaded Inverted Pendulum (SLIP) Model of a Bio-Inspired Quadrupedal Robot Over Compliant Terrains

2018 ◽  
Author(s):  
Hasti Hayati ◽  
Paul Walker ◽  
Terry Brown ◽  
Paul Kennedy ◽  
David Eager
Keyword(s):  
Degrees Of Freedom ◽  
Inverted Pendulum ◽  
Viscoelastic Behavior ◽  
Slip Model ◽  
Runge Kutta Method ◽  
Synthetic Rubber ◽  
Spring Loaded Inverted Pendulum ◽  
Single Support Phase ◽  
The Impact ◽  
Three Degrees Of Freedom

To study the impact of compliant terrains on the biomechanics of rapid legged movements, a well-known spring loaded inverted pendulum (SLIP) model is deployed. The model is a three-degrees-of-freedom system (3 DOF), inspired by galloping greyhounds competing in a racing condition. A single support phase of hind-leg stance in a galloping gait is taken into consideration due to its primary function in powering the greyhounds locomotion and higher rate of musculoskeletal injuries. To obtain and solve the nonlinear second-order differential equation of motions, the Lagrangian method and MATLABb R2017b (ode45 solver), which is based on the Runge-Kutta method, has been used, respectively. To get the viscoelastic behavior of compliant terrains, a Clegg hammer test was developed and performed five times on each sample. The effective spring and damping coefficients of each sample were then determined from the hysteresis curves. The results showed that galloping on the synthetic rubber requires more muscle force compared with wet sand. However, according to the Clegg hammer test, wet sand had a higher impact force than synthetic rubber which can be a risk factor for bone fracture, particularly hock fracture, in greyhounds. The results reported in this paper are not only useful for identifying optimum terrain properties and injury thresholds of an athletic track, but also can be used to design control methods and shock impedances for legged robots performing on compliant terrains.

Impact Loading Analysis of Light Sport Aircraft Landing Gear

2014 ◽  
Vol 518 ◽  
pp. 252-257 ◽  
Author(s):  
Pu Woei Chen ◽  
Shu Han Chang ◽  
Chan Ming Chen
Keyword(s):  
Simulation Model ◽  
Impact Loading ◽  
Loading Condition ◽  
Element Model ◽  
Landing Gear ◽  
Market Demand ◽  
Critical Loading ◽  
Aircraft Landing ◽  
Aluminum Plates ◽  
The Impact

This paper examined the critical loading condition of a light sport aircrafts main landing gear during the impact loading condition. The new category airplane was established by the FAA in 2004. The light sport aircraft has great market demand for personnel entertainment purpose and regional transportation. The main object of this research was to establish a static and dynamic loading simulation model for the aluminum alloy landing gear of a light sport aircraft. This work also examined the critical loading parameters of the main landing gear, including the maximum take-off weight and maximum stall speed. The analysis was performed using ANSYS and LS-DYNA to establish the finite element model after simplifying the geometric characteristics and verifying the results by energy conservation, hourglass energy, and sliding energy. The study tested aluminum plates with a thickness from 15~25 mm. The results showed all the samples could sustain the required loading condition, except for the thickness of 15mm that failed under impact loading. The simulation model provides a cost-saving process compared to a real crashworthiness drop test to test the main landing gears compliance with regulations.

The Impact of Nonlinear of Tire on Multi-Axle Vehicle Steering

2011 ◽  
Vol 403-408 ◽  
pp. 3424-3429 ◽  
Author(s):  
Huan Wang ◽  
Xiu Hua Gao ◽  
Jian Kai Chen ◽  
Chao Wang
Keyword(s):  
Degrees Of Freedom ◽  
Vehicle Body ◽  
Step Response ◽  
Slip Angle ◽  
Rolling Angle ◽  
Side Slip Angle ◽  
Bp Neural Network Model ◽  
Yaw Angle ◽  
The Impact ◽  
Three Degrees Of Freedom

BP neural network model of tire and three degrees of freedom dynamic model of Multi-Axle vehicle were built. According to Zero side slip angle control theory, with the use of MATLAB software, comparative analysis of the step response of the vehicle side slip angle, yaw angle velocity and rolling angle in the driving vehicle with linear and nonlinear tires was done. The results show thatMulti-Axle vehicle with nonlinear tires has obvious affect between side slip angle and yaw angle velocity of the vehicle body. Relative to Multi-Axle vehicle with linear tires, the overshoot of step response increases greatly, and the Steady-State value does not equal to zero; but rolling angle of the vehicle with nonlinear tires has less affected.

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.

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