On Planar Impacts of Cylinders and Balls

2019 ◽  
Vol 86 (7) ◽  
Author(s):  
Khalid Alluhydan ◽  
Pouria Razzaghi ◽  
Yildirim Hurmuzlu
Keyword(s):  
Rigid Body ◽  
Coefficient Of Restitution ◽  
Experimental Results ◽  
Discretization Method ◽  
Stiffness Ratio ◽  
Hertz Model ◽  
Local Contact ◽  
Contact Models ◽  
Simulation Results ◽  
Number Of Segments

In this paper, we studied planar collisions of balls and cylinders with an emphasis on the coefficient of restitution (COR). We conducted a set of experiments using three types of materials: steel, wood, and rubber. Then, we estimated the kinematic COR for all collision pairs. We discovered unusual variations among the ball–ball (B–B) and ball–cylinder (B–C) CORs. We proposed a discretization method to investigate the cause of the variations in the COR. Three types of local contact models were used for the simulation: rigid body, bimodal linear, and bimodal Hertz models. Based on simulation results, we discovered that the bimodal Hertz model produced collision outcomes that had the greatest agreement with the experimental results. In addition, our simulations showed that softer materials need to be segmented more than harder ones. Softer materials are materials with smaller collision stiffness values than harder ones. Moreover, we obtained a relationship between the collision stiffness ratio and the number of segments of softer materials to produce physically accurate simulations of B–C CORs. We validated this relationship and the proposed method by conducting two additional sets of experiments.

Dynamics of a Radially Rotating Beam With Impact, Part 1: Theoretical and Computational Model

1990 ◽  
Vol 112 (1) ◽  
pp. 65-70 ◽  
Author(s):  
A. S. Yigit ◽  
A. G. Ulsoy ◽  
R. A. Scott
Keyword(s):  
Rigid Body ◽  
Computational Model ◽  
Computational Algorithm ◽  
Coefficient Of Restitution ◽  
Experimental Results ◽  
Body Motion ◽  
Momentum Balance ◽  
Rotating Beam ◽  
Before And After ◽  
Simulation Results

A model is presented for the dynamics of a radially rotating beam with impact. The model uses a momentum balance method and a coefficient of restitution, and enables one to predict the rigid body motion as well as the elastic motion before and after impact. A computational algorithm is also developed to implement the model. In Part 2 simulation results will be compared with experimental results to investigate the validity of the model.

Modeling and Simulation for Trajectory of TV-Guided Projectile

2015 ◽  
Vol 713-715 ◽  
pp. 278-282
Author(s):  
Ming Hou ◽  
Qiang Han ◽  
Han Chang Wang ◽  
Si Min Bi
Keyword(s):  
Rigid Body ◽  
Modeling And Simulation ◽  
Tilt Angle ◽  
Theoretical Basis ◽  
Attack Angle ◽  
Experimental Results ◽  
Simulation Program ◽  
Trajectory Model ◽  
Simulation Results

Through the analysis of the role of the force and moment on TV-guided projectile, the rigid body trajectory model of the projectile is established, and the simulation program of trajectory is developed based on MATLAB. The simulation results are basically consistent with the experimental results, so the trajectory model can reflect the characteristics of the TV-guided projectile. The characteristics of trajectory, velocity, trajectory tilt angle and attack angle are analyzed by simulations that can provide theoretical basis for improving correction precision.

A Critical Study of the Applicability of Rigid-Body Collision Theory

1996 ◽  
Vol 63 (2) ◽  
pp. 307-316 ◽  
Author(s):  
D. Stoianovici ◽  
Y. Hurmuzlu
Keyword(s):  
Rigid Body ◽  
High Speed ◽  
Equations Of Motion ◽  
Coefficient Of Restitution ◽  
Electrical Circuit ◽  
Experimental Results ◽  
Critical Study ◽  
Low Velocity ◽  
Steel Bars ◽  
Body Theory

This article deals with the collision of steel bars with external surfaces. The central issue of the article is the investigation of the fundamental concepts that are used to solve collision problems by using rigid-body theory. We particularly focus on low-velocity impacts of relatively rigid steel bars to test the applicability of these concepts. An experimental analysis was conducted to study the rebound velocities of freely dropped bars on a large external surface. A high-speed video system was used to capture the kinematic data. The number of contacts and the contact time were determined by using an electrical circuit and an oscilloscope. Tests were performed by using six bar lengths and varying the pre-impact inclinations and the velocities of the bars. The experimental results were used to verify the applicability of Coulomb’s law of friction and the invariance of the coefficient of restitution in the class of impacts considered in this study. Then, given the unusual variation the coefficient of restitution as a result of changing pre-impact inclinations, a theoretical model was developed to explain this variation. A discrete model of the bar was used to obtain the equations of motion during impact. Computed and experimental results were compared to establish the accuracy of numerical model. The internal vibrations of the bar and multi impacts between the bar and the surface were found to be two main factors that cause the variation of the coefficient of restitution. Furthermore, a slenderness factor was proposed to identify the subset of collision problems where the coefficient of restitution was invariant to the inclination angle.

Predicting the Permanent Deformation After the Impact of a Rod With a Flat Surface

2014 ◽  
Vol 137 (1) ◽  
Author(s):  
Hamid Ghaednia ◽  
Dan B. Marghitu ◽  
Robert L. Jackson
Keyword(s):  
Flat Surface ◽  
Impact Force ◽  
Permanent Deformation ◽  
Element Model ◽  
Coefficient Of Restitution ◽  
Experimental Results ◽  
Normal Impact ◽  
Previous Contact ◽  
Contact Models ◽  
The Impact

In this study, a new expression for the permanent deformation after the impact of a rod with a flat surface is given. Both flat and the surface have been considered elastoplastic. The contact has been considered frictionless and has been divided into three phases, the elastic, the elastoplastic, and the unloading phase. For the normal impact force in the loading phase, we considered a nonlinear expression that satisfies the effect of deformation on both objects by using a finite element model. For the unloading phase, the contact force has been considered to follow the Hertz theory. The simulation and experimental results were conducted for different initial impact velocities of the rod. Permanent deformation after the impact and the motion of the rod has been measured accurately in the experiments. Based on the simulation and experimental results an expression for the permanent deformation has been developed. Finally, the model has been verified and compared with previous contact models in terms of the coefficient of restitution.

Simulation of carding condensing process

2021 ◽  
pp. 004051752098812
Author(s):  
Xixi Qian ◽  
Yuanying Shen ◽  
Qiaoli Cao ◽  
Jun Ruan ◽  
Chongwen Yu
Keyword(s):  
Experimental Results ◽  
Simulation Results ◽  
Carding Machine ◽  
The Web

A simulation describing the fiber movement during the condensation was conducted, and the effect of the condensation in the carding machine was studied. The simulation results showed that the condensation has the blending and the evening effect on the condensed sliver, which can be explained by the fiber rearrangement. Moreover, the increasing web width and the decreasing condensing length can result in a more uniform sliver. Further, the evening effect of the web width on the web was verified by experiments. The simulation results were in general agreement with the experimental results.

A UMDA-Based Discretization Method for Continuous Attributes

2011 ◽  
Vol 403-408 ◽  
pp. 1834-1838
Author(s):  
Jing Zhao ◽  
Chong Zhao Han ◽  
Bin Wei ◽  
De Qiang Han
Keyword(s):  
Machine Learning ◽  
Data Mining ◽  
Evolutionary Algorithms ◽  
Marginal Distribution ◽  
Convergence Speed ◽  
Fast Convergence ◽  
Experimental Results ◽  
Discretization Method ◽  
Bottom Up ◽  
Global Dynamic

Discretization of continuous attributes have played an important role in machine learning and data mining. They can not only improve the performance of the classifier, but also reduce the space of the storage. Univariate Marginal Distribution Algorithm is a modified Evolutionary Algorithms, which has some advantages over classical Evolutionary Algorithms such as the fast convergence speed and few parameters need to be tuned. In this paper, we proposed a bottom-up, global, dynamic, and supervised discretization method on the basis of Univariate Marginal Distribution Algorithm.The experimental results showed that the proposed method could effectively improve the accuracy of classifier.

The Effect of Different Turbulence Models on the Emitter Discharge by Using Computational Fluid Dynamics

2013 ◽  
Vol 662 ◽  
pp. 586-590
Author(s):  
Gang Lu ◽  
Qing Song Yan ◽  
Bai Ping Lu ◽  
Shuai Xu ◽  
Kang Li
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Flow Field ◽  
Turbulence Models ◽  
Experimental Results ◽  
Turbulent Model ◽  
Simulation Results ◽  
Rsm Model ◽  
Dynamics Method ◽  
Emitter Discharge

Four types of Super Typhoon drip emitter with trapezoidal channel were selected out for the investigation of the flow field of the channel, and the CFD (Computational Fluid Dynamics) method was applied to simulate the micro-field inside the channel. The simulation results showed that the emitter discharge of different turbulent model is 4%-14% bigger than that of the experimental results, the average discharge deviation of κ-ω and RSM model is 5, 4.5 respectively, but the solving efficiency of the κ-ω model is obviously higher than that of the RSM model.

Design of Magnetic Levitated Thrust Bearing Experiment Table

2011 ◽  
Vol 199-200 ◽  
pp. 597-602
Author(s):  
Shou Fa Liu ◽  
Zhang Jie Shi ◽  
Chun Feng Li
Keyword(s):  
Thrust Bearing ◽  
Deformation Measurement ◽  
Experimental Results ◽  
Electromagnetic Parameters ◽  
Ansys Simulation ◽  
Overall Design ◽  
Experimental Parameters ◽  
Structural Dimensions ◽  
Simulation Results

In this paper, the overall design of magnetic levitated thrust bearing experiment table was completed, of which the main experimental parameters those are electromagnetic parameters and structural dimensions were determined, in addition, the joint debugging and deformation measurement are performed. Analysis results showed that theoretical value, ANSYS simulation results and experimental results were similar, which said that it is feasible to perform stiffness check of the thrust collar on the experiment table.

SIMULATION OF DYNAMIC EVENT OF IMPACT USING EXPLICIT 3D FEM MODEL AND VALIDATION BY EXPERIMENT AND CONTACT MODELS

2021 ◽  
Vol 6 (3) ◽  
Author(s):  
Akshay Mallikarjuna ◽  
Dan Marghitu ◽  
P.K. Raju
Keyword(s):  
Material Properties ◽  
Permanent Deformation ◽  
Oblique Impact ◽  
Coefficient Of Restitution ◽  
Impact Behavior ◽  
3D Fem ◽  
Dynamic Event ◽  
Contact Models ◽  
Explicit Dynamic ◽  
The Impact

— In this study, an optimized method to simulate the dynamic 3D event of the impact of a rod with a flat surface has been presented. Unlike the 2D FEM based contact models, in this study both the bodies undergoing the impact are considered elastic(deformable) and simulation is the dynamic event of the impact, instead of predefined 2D symmetric contact analysis. Prominent contact models and plasticity models to define material properties in ANSYS are reviewed. Experimentation results of normal and oblique impact of the rod for different rods provided the coefficient of restitution. Experimental results of permanent deformation on the base for different impact velocity is derived out of a prominent impact study. The simulation results are in co-relation with experiment and both indentation and flattening models on the coefficient of restitution (COR) and permanent deformation of the base and rod after the impact. Thus, the presented 3D Explicit Dynamic simulation of impact is validated to analyze the impact behavior of the 2 bodies without any predefined assumptions with respect to boundary conditions or material properties.

scholarly journals Numerical Simulations of V-Shaped Plates Subjected to Blast Loadings: A Validation Study

2016 ◽  
Vol 10 (11) ◽  
pp. 203
Author(s):  
Mohd Zaid Othman ◽  
Qasim H. Shah ◽  
Muhammad Akram Muhammad Khan ◽  
Tan Kean Sheng ◽  
M. A. Yahaya ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Numerical Simulations ◽  
Variable Mass ◽  
Blast Loading ◽  
Experimental Results ◽  
Average Difference ◽  
Simulation Results ◽  
Blast Loadings ◽  
Carrier Vehicle ◽  
Good Agreement

A series of numerical simulations utilizing LS-DYNA was performed to determine the mid-point deformations of V-shaped plates due to blast loading. The numerical simulation results were then compared with experimental results from published literature. The V-shaped plate is made of DOMEX 700 and is used underneath an armour personal carrier vehicle as an anti-tank mine to mitigate the effects of explosion from landmines in a battlefield. The performed numerical simulations of blast loading of V-shaped plates consisted of various angles i.e. 60°, 90°, 120°, 150° and 180°; variable mass of explosives located at the central mid-point of the V-shaped vertex with various stand-off distances. It could be seen that the numerical simulations produced good agreement with the experimental results where the average difference was about 26.6%.

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