Modelling Local Dynamic Pressure Within Inflatable Sports Balls

2012 ◽  
Author(s):  
Henry Hanson ◽  
Andy Harland ◽  
Chris Holmes ◽  
Dan Price ◽  
Tim Lucas
Keyword(s):  
Impact Analysis ◽  
Dynamic Pressure ◽  
Finite Element Models ◽  
Local Dynamic ◽  
Uniform Pressure ◽  
Pressure Method ◽  
Modelling Techniques ◽  
Internal Pressures ◽  
The Impact ◽  
Good Agreement

This study used a coupled Eulerian Lagrangian (CEL) approach to model the air within a football (soccer ball) during two types of impacts. Conventional modelling techniques (and those used in all previous football finite element models known by the author) utilize a uniform pressure method incapable of accounting for spatial pressure variation. Internal pressures and deformations for the CEL and uniform pressure models were within a few percent of each other, indicating good agreement between pressurization techniques. By necessity, the air was defined with different methods in each model and this may have contributed to a discrepancy in maximum internal pressure. Using the CEL model, the pressure wave generated at impact was observed to travel from one side of the ball to the other at the speed of sound. Though the CEL model helped illustrate the impact scenario, there were no clear distinctions that gave it an advantage over the uniform pressure method for simple impact analysis.

The penetration and ricochet of ogive-nosed rigid projectiles obliquely impacting metallic targets

2021 ◽  
pp. 204141962110377
Author(s):  
Yaniv Vayig ◽  
Zvi Rosenberg
Keyword(s):  
Experimental Data ◽  
Numerical Simulations ◽  
Dynamic Pressure ◽  
Oblique Impacts ◽  
Simulation Results ◽  
The Impact ◽  
Penetration Depths ◽  
Resistance To Penetration ◽  
Good Agreement

A large number of 3D numerical simulations were performed in order to follow the trajectory changes of rigid CRH3 ogive-nosed projectiles, impacting semi-infinite metallic targets at various obliquities. These trajectory changes are shown to be related to the threshold ricochet angles of the projectile/target pairs. These threshold angles are the impact obliquities where the projectiles end up moving in a path parallel to the target’s face. They were found to depend on a non-dimensional entity which is equal to the ratio between the target’s resistance to penetration and the dynamic pressure exerted by the projectile upon impact. Good agreement was obtained by comparing simulation results for these trajectory changes with experimental data from several published works. In addition, numerically-based relations were derived for the penetration depths of these ogive-nosed projectiles at oblique impacts, which are shown to agree with the simulation results.

Simulations of Reacting Fluidized Beds Using an Agent-Based Bubble Model

2003 ◽  
Vol 1 (1) ◽  
Author(s):  
S. Pannala ◽  
C.Stuart Daw ◽  
John Halow
Keyword(s):  
Gas Flow ◽  
Bubble Dynamics ◽  
Dynamic Pressure ◽  
Emergent Behavior ◽  
Ozone Decomposition ◽  
Agent Based ◽  
Dynamic Pressure Measurements ◽  
Bubbling Beds ◽  
The Impact ◽  
Good Agreement

We apply a low-order dynamical model for simulating the conversion of bubbling bed reactors. The model includes mass-transfer and first-order reactions between the gas and solids and accounts for upward motion and interactions between bubbles. On a time-average basis, we get reasonably good agreement between the model and experimental measurements from an ozone decomposition reactor. The collective result of the bubble dynamics is a type of global emergent behavior characterized by the formation of a pulsing central channel of high void fraction and high gas flow. These pulsations appear to be similar in character to those typically seen in dynamic pressure measurements of bubbling beds. We use our model to explore the impact of these pulsations on reactor conversion.

scholarly journals Experimental Validation of an Elastic-Plastic Contact Model

2011 ◽  
Author(s):  
M. R. Brake ◽  
P. L. Reu ◽  
D. J. VanGoethem ◽  
M. V. Bejarano ◽  
A. Sumali
Keyword(s):  
Numerical Models ◽  
Hard Metal ◽  
Finite Element Models ◽  
Elastic Plastic ◽  
Engineering Problems ◽  
Engineered Structures ◽  
Series Of Experiments ◽  
The Impact ◽  
Impact Events ◽  
Good Agreement

In many engineered structures and components, impact events frequently occur between sub-components. Numerical models are able to adequately capture the salient features of these events; however, with high fidelity finite element models, an unreasonably large number of elements are needed to accurately model just the elastic regime when arbitrary contact is considered. In order to solve real engineering problems with elastic-plastic impacts in complex or built up systems, an analytical expression is needed to make solutions practical. To this end, a series of experiments are designed to test a new elastic plastic model for impact dynamics. A hard metal ball is attached as the end of a pendulum, and is struck against a relatively compliant metal puck. Digital image analysis is used to measure the displacement and velocity of the metal ball across the impact events. Frictional losses in the system are minimized, and the coefficient of restitution is calculated as a function of velocity. These measurements are used to validate an elastic-plastic impact model, which is further compared to and other models from the literature. Good agreement is found between the new analytical model and the experiments.

Use of Statical Indentation Laws in the Impact Analysis of Laminated Composite Plates

1985 ◽  
Vol 52 (1) ◽  
pp. 6-12 ◽  
Author(s):  
T. M. Tan ◽  
C. T. Sun
Keyword(s):  
Impact Analysis ◽  
Laminated Composite ◽  
Composite Plates ◽  
Impact Response ◽  
Low Velocity Impact ◽  
Low Velocity ◽  
The Impact ◽  
Theoretical Results ◽  
Theoretical Procedure ◽  
Good Agreement

The low-velocity impact response of graphite/epoxy laminates was investigated theoretically and experimentally. A nine-node isoparametric plate finite element in conjunction with an empirical contact law was used for the theoretical investigation. Theoretical results are in good agreement with strain-gage experimental data. The results of the investigation indicate that the present theoretical procedure describes the impact response of laminate for low-impact velocities.

Elementary Three-Dimensional Interactive Rotor Blade Impact Analysis

1976 ◽  
Vol 98 (4) ◽  
pp. 480-486 ◽  
Author(s):  
R. W. Cornell
Keyword(s):  
Impact Analysis ◽  
Impact Force ◽  
Three Dimensional ◽  
Soft Or ◽  
Mass System ◽  
Centrifugal Stiffening ◽  
Modes Of Vibration ◽  
Fan Blade ◽  
The Impact ◽  
Good Agreement

A theoretical analysis is presented which defines the loading and response of a rotor fan blade due to soft or frangible impacts in terms of the three fundamental modes of vibration by representing the blade as a lumped, spring-mass system. The analysis includes the effects of centrifugal stiffening, blade twist, retention stiffness and orientation, damping, and blade motion and deflection on the impact force. The features, solution, program, and applications of this analysis are reviewed, and the results are compared with those from a number of blade and specimen tests and found to be in good agreement.

Simplified Method for Predicting Impact Loads of Solid-Walled Transportation Packagings for Radioactive Materials

1989 ◽  
Vol 111 (3) ◽  
pp. 316-321 ◽  
Author(s):  
W. W. Teper ◽  
R. G. Sauve´
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Impact Analysis ◽  
Impact Force ◽  
Impact Loads ◽  
Radioactive Materials ◽  
Element Analysis ◽  
Elastic Plastic ◽  
The Impact ◽  
Good Agreement

Transportation packagings for radioactive materials must withstand severe impact conditions without loss of integrity and without excessive permanent distortions in the seal regions. The compliance with the requirements may be shown either through extensive testing, elastic-plastic impact analysis, or a combination of both. Elastic-plastic finite element analysis, although less costly than testing, is usually expensive and time consuming. In this paper, simplified methods for determining the impact force are presented for the following impact cases of solid-walled casks: impact on a pin, impact on an edge, and impact on a corner. The results of the simplified methods are in good agreement with the results of elastic-plastic finite element analysis. It is shown that in each case almost the entire impact energy is dissipated by the plastic deformation of the material in the impact zone.

The Impact of a Potential Public/Private Initiative on a Defined Region of the South Suburban Chicago Metropolitan Area

2019 ◽  
pp. 14-32
Keyword(s):  
Supply Chain ◽  
Economic Impact ◽  
Impact Analysis ◽  
Census Data ◽  
Economic Benefits ◽  
Local Economy ◽  
Market Area ◽  
State And Local ◽  
The University ◽  
The Impact

The university is considered one of the engines of growth in a local economy or its market area, since its direct contributions consist of 1) employment of faculty and staff, 2) services to students, and supply chain links vendors, all of which define the University’s Market area. Indirect contributions consist of those agents associated with the university in terms of community and civic events. Each of these activities represent economic benefits to their host communities and can be classified as the economic impact a university has on its local economy and whose spatial market area includes each of the above agents. In addition are the critical links to the University, which can be considered part of its Demand and Supply chain. This paper contributes to the field of Public/Private Impact Analysis, which is used to substantiate the social and economic benefits of cooperating for economic resources. We use Census data on Output of Goods and Services, Labor Income on Salaries, Wages and Benefits, Indirect State and Local Taxes, Property Tax Revenue, Population, and Inter-Industry to measure economic impact (Implan, 2016).

Modeling of Tread Block Contact Mechanics Using Linear Viscoelastic Theory3

2008 ◽  
Vol 36 (3) ◽  
pp. 211-226 ◽  
Author(s):  
F. Liu ◽  
M. P. F. Sutcliffe ◽  
W. R. Graham
Keyword(s):  
High Speed ◽  
Slip Rate ◽  
Material Model ◽  
Contact Forces ◽  
Block Modeling ◽  
Rate Dependent ◽  
Linear Viscoelastic Material ◽  
Linear Viscoelastic ◽  
The Impact ◽  
Good Agreement

Abstract In an effort to understand the dynamic hub forces on road vehicles, an advanced free-rolling tire-model is being developed in which the tread blocks and tire belt are modeled separately. This paper presents the interim results for the tread block modeling. The finite element code ABAQUS/Explicit is used to predict the contact forces on the tread blocks based on a linear viscoelastic material model. Special attention is paid to investigating the forces on the tread blocks during the impact and release motions. A pressure and slip-rate-dependent frictional law is applied in the analysis. A simplified numerical model is also proposed where the tread blocks are discretized into linear viscoelastic spring elements. The results from both models are validated via experiments in a high-speed rolling test rig and found to be in good agreement.

Impact Analysis of the Mechanization Program for Tribal Paddy Farmers of Goa

2019 ◽  
Vol 6 (1) ◽  
Author(s):  
MATHALA JULIET GUPTA ◽  
ASHISH M. PITRE ◽  
SUMATI CHAVAN PANDURNAG ◽  
SALONI SALIL VANJARI
Keyword(s):  
Impact Analysis ◽  
Field Capacity ◽  
Significant Saving ◽  
Manual Methods ◽  
Paddy Farmers ◽  
The Impact ◽  
And Training

This paper assessed the impact of the mechanization of the 8 tribal paddy farmers’ groups of Goa benefited in the year 2011 through the Tribal sub-plan program of ICAR-CCARI through results of surveys conducted in 2012 and 2015. Shift to mechanization among beneficiaries was significant in power tillers (64-100%) but less in power reapers(0-91%). Also significant saving in manpower (Power tillers:33.3% to 60%, power reapers: 33.3% to 83.3%), , time (field capacity increased (power tillers : 41.7% to141%, power reapers :58.1% to 912.8%) and cost(power tillers :44.7% to 59.1%, power reapers : 57.8% to 82.9%) was reportedthrough the use of equipment as compared to desi plough or manual methods of harvesting. Some constraints like lack of access roads and training in use and maintenance of the equipment were reported by the beneficiary farmers.

Dynamic model for high-speed rotors based on their experimental characterization

2017 ◽  
Vol 2 (4) ◽  
pp. 25
Author(s):  
L. A. Montoya ◽  
E. E. Rodríguez ◽  
H. J. Zúñiga ◽  
I. Mejía
Keyword(s):  
Dynamic Model ◽  
High Speed ◽  
Natural Frequencies ◽  
Mode Shapes ◽  
Experimental Characterization ◽  
Rotating Systems ◽  
Computing Performance ◽  
The Impact ◽  
Stiffness Distribution ◽  
Good Agreement

Rotating systems components such as rotors, have dynamic characteristics that are of great importance to understand because they may cause failure of turbomachinery. Therefore, it is required to study a dynamic model to predict some vibration characteristics, in this case, the natural frequencies and mode shapes (both of free vibration) of a centrifugal compressor shaft. The peculiarity of the dynamic model proposed is that using frequency and displacements values obtained experimentally, it is possible to calculate the mass and stiffness distribution of the shaft, and then use these values to estimate the theoretical modal parameters. The natural frequencies and mode shapes of the shaft were obtained with experimental modal analysis by using the impact test. The results predicted by the model are in good agreement with the experimental test. The model is also flexible with other geometries and has a great time and computing performance, which can be evaluated with respect to other commercial software in the future.

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