Experimental Validation of Theoretical Model for Centric Dumped Collision between Two Balls (original) (raw)

Review of the Dynamic Behaviour of Sports Balls during Normal and Oblique Impacts

In this paper are review of impact experiment to study the dynamic behaviour of sports ball during oblique and normal impacts. In previous studies, the investigation was done on the dynamic behaviour of a sports ball during oblique and normal impacts from experimental, numerical, and theoretical viewpoints. The experimental results are analysed and compared with the theories, in order to understand the dynamics behaviours based on the phenomenological occurrence. Throughout the experimental studies previously, there are results of dynamics behaviours examined by many researchers such as the coefficient of restitution, tangential coefficient, local deformation, dynamic impact force, contact time, angle of impact (inbound and rebound), spin rate of the ball, ball stiffness and damping coefficient which dependable of the initial or impact velocity.

The Use of Shock Waves in Ensuring Accuracy of a Ball Launcher for Collision Study

The paper presents a ball launcher used for the study of collisions. Knowing the precise data on kinematical parameters at launching and time measurements from launching until the first impact is a very important issue. An acoustic method is employed in finding the time period between the launch and the collision. In a first stage, the moment of launching was estimated with great errors. Therefore, design improvements were completed and, by means of shock waves generated in the launching mechanisms, the precise identification of the launching moment is made and implicitly, the flying duration.

AN EVALUATION OF A SIMPLE DYNAMICAL MODEL FOR IMPACTS BETWEEN RIGID OBJECTS

2009

The main purpose of this work is to propose a dynamical model for simulating the response of different metallic objects when impacted by another rigid body. In addition, a methodology for estimating the model parameters is presented and discussed. Results from real experiments shows that by assuming certain characteristics on impacting objects, the dynamic model can reproduce the transient dynamics

Experimental analysis of the kinematics in the elastic collision between two bodies during the contact time

The elastic collision between two bodies is a fleeting event challenging to observe due to its infinitesimally short contact time, usually lasting mere hundredths or even thousandths of a second. This brief duration poses significant challenges for accurately measuring velocities and impulsive forces and establishing representative functions. Consequently, this study aims to address these challenges. Experimental measurements of velocity, acceleration, and force changes during the contact period are crucial for validating theoretical models and functions that accurately represent the dynamics of collisions under realistic conditions. These measurements are critical in optimizing the activation response of airbag and restraint systems in vehicles and are fundamental in reconstructing physical scenarios of accidents. The experiments were conducted in a practical computer-assisted laboratory, utilizing wireless sensors embedded within the test vehicles and positioned on a low-friction track. The collision setup was designed to be horizontal and frontal, ensuring that the bodies involved did not undergo permanent deformations. The primary methodology adopted in this analysis integrates both quantitative and qualitative approaches, focusing on collecting and analyzing numerical data to identify patterns and establish mathematical relationships between variables. This integrated approach offers a more comprehensive understanding of the kinematics of colliding vehicles during the contact period.

Experimental and numerical study of ball size effect on restitution coefficient in low velocity impacts

2010

In this article, the Coefficient of Restitution (COR) and Energy Loss Percentage (ELP) of one-dimensional impacts are determined experimentally for different ball sizes using a drop test apparatus. Ball diameters range from 6 to 12 mm, made of steel and aluminum dropped on steel and aluminum sheets. Furthermore, effects of ball sizes on COR and contact time duration are studied numerically. In addition, time variation of displacement of the midpoint of sheet's top surface and vibration of the ball's center are investigated. This is done using a finite element model for elasto-plastic collisions. In this work, dynamic and explicit analyses have been carried out by using the LS-DYNA module of ANSYS. The numerical results are validated by the present experimental data. Moreover, the present results are compared with previous works. Results show that COR decreases as balls' diameters increase.

Rebound Property in Low Velocity Impact of Two Equivalent Balls

The present study focuses on an impact phenomenon of two spheres and its rebound property. The collision of two spheres is a fundamental problem with impact phenomenon. The coefficient of restitution characterizes the property of impact phenomenon and has been estimated in general by experiment. In addition, it has been tried to estimate the coefficient by analytical and numerical methods. Considering body deformation, the body is deflected rapidly in collision and the strain rate occurred in the body is significantly high. It is well known the yield stress of the specific industrial material depends on the strain rate. However, it has not been proved the relationship between the coefficient of restitution and the strain rate in details yet. The present paper discusses the coefficient of restitution in low velocity impact of two equivalent balls. The impact experiments were conducted for the balls with different diameters by a pendulum impact apparatus. And the balls are numerically analyzed based on the finite element method considering the dependence of yield stress on strain rate as the material property of the balls. In conclusion, the strain rate decreases with the increment of the ball diameter and, it causes the coefficient of restitution to decrease.

IJERT-Numerical Investigation And Simulation of Impact Energy Absorption by Materials in Ballstic

International Journal of Engineering Research and Technology (IJERT), 2021

https://www.ijert.org/numerical-investigation-and-simulation-of-impact-energy-absorption-by-materials-in-ballstic https://www.ijert.org/research/numerical-investigation-and-simulation-of-impact-energy-absorption-by-materials-in-ballstic-IJERTV10IS060190.pdf This report treats terminal ballistics which is the branch of the ballistic science concerning the mechanics of impact. The purpose of this project is to determine the parameters governing projectile failure when impact against a target is achieved and energy loss of projectile in each layer of composite are observed. In the Simulation approach, a model has been derived capable of determining the amount of deformation in the projectile after impact, energy summary in each layer An Simulation method of obtaining the resistance pressure, by which the target resists penetration, and a method of determining the energy loss project tile material are also implemented. A numerical section explaining the main factors and approaches in hydro code and dynamic modeling is also devised along with simulations of projectile impact.

An experimental study of the impact of a sepak takraw ball on a flat surface

The Impact of Technology on Sport III. RMIT University Publisher (2009). Chapter: Design, pp 447- 452, ISBN 13: 978-1-921426-39-1.

The takraw ball is a very unique interwoven ball used in the action game of sepak takraw. The traditional takraw ball is manufactured by conventionally weaving split rattan strips into a spherical basket. Modern takraw balls are manufactured by forming strips of plastics materials into interwoven hoop. These interwoven hoops form 12 holes and 20 intersections. To date there has been no studies on the dynamic behavior and mechanical properties of the takraw ball. The purpose of this study is to predict the dynamic behavior and mechanical properties of the takraw ball in particular of normal impact on flat surfaces at low speeds. Two methods are employed to measure the dynamics behavior and mechanical properties of the takraw ball. The impact force, contact time, coefficient of restitution, deformation of the ball, inbound and rebound velocity were measured by using two dimensional motion analysis of high-speed video data and force plate data. Then, a finite element (FE) model of the homogeneous takraw ball is constructed, based on the experimental results. This FE model is used to predict modulus elasticity and Poisson ratio of the takraw ball. The FE analysis solution of the ball model was found to be reasonable close with the experimental results. However further improvement need to be done by taking into consideration the nonlinearity of the takraw ball under large deformation as well as at high impact velocity.

An investigation of the comparative behaviour of alternative contact force models during elastic collisions

Powder Technology, 2011

In this paper the rebound kinematics obtained using different contact force models are compared for the simple problem of an elastic sphere impacting obliquely with a target wall. It is shown that, for an appropriately calibrated normal spring stiffness and a realistic ratio of the tangential to normal spring stiffnesses, excellent results can be obtained by using a simple linear spring model. The paper also demonstrates that for non-linear contact models, integral equations for the tangential force-displacement cannot be used as the spring stiffness varies during the collision. Finally some comments are provided regarding the limitations of the linear spring model and alternatives are discussed.