Spatial Impact of a Slender Beam

2002 ◽  
Author(s):  
Horatiu Barbulescu ◽  
Dan B. Marghitu ◽  
Uday Vaidya
Keyword(s):  
Composite Materials ◽  
Incident Angle ◽  
Contact Point ◽  
Equations Of Motion ◽  
Coefficient Of Restitution ◽  
Tangential Component ◽  
Sliding Direction ◽  
Generalized Momentum ◽  
Separation Force ◽  
The Impact

In this paper, the dynamics of the spatial impact of a slender beam is analyzed. The equations of motion are calculated using Kane’s impact method. The generalized momentum and generalized impulse of the beam are considered to find the equations of motion of the beam. The frictional phenomenon at the contact point is analyzed. For the case of impact without slipping, it is used the assumption that the tangential component of the velocity of separation is null. In the case with slipping, the tangential impulse (at the plane of impact) is computed. The sliding direction after impact is calculated. A simulation of the impact of beam with a surface is developed and the velocity of separation, force of impact and kinetic energy of the beam after impact are studied for different incident angles of the beam. The incident angle is varied from 0° to 57°. The results are function of the incident angle of impact. The results can be used to calculate the coefficient of restitution and friction for composite materials.

Spatial Impact of a Slender Beam

2003 ◽  
Vol 125 (4) ◽  
pp. 368-371 ◽  
Author(s):  
Horatiu Barbulescu ◽  
Dan B. Marghitu ◽  
Uday Vaidya
Keyword(s):  
Kinetic Energy ◽  
Incident Angle ◽  
Contact Point ◽  
Equations Of Motion ◽  
Tangential Component ◽  
Sliding Direction ◽  
Generalized Momentum ◽  
Separation Force ◽  
The Impact

In this paper, the dynamics of the spatial impact of a slender beam is analyzed. The equations of motion are calculated using Kane’s impact method. The generalized momentum and generalized impulse of the beam are considered to find the equations of motion of the beam. The frictional phenomenon at the contact point is analyzed. For the case of impact without slipping, it is used the assumption that the tangential component of the velocity of separation is null. In the case with slipping, the tangential impulse (at the plane of impact) is computed. The sliding direction after impact is calculated. A simulation of the impact of beam with a surface is developed and the velocity of separation, force of impact and kinetic energy of the beam after impact are studied for different incident angles of the beam. The incident angle is varied from 0 deg to 57 deg. The results are function of the incident angle of impact.

scholarly journals Mathematical Modeling of Impact of Possible Shock Dynamic Loads on the Modern Composite Materials

2019 ◽  
Vol 224 ◽  
pp. 02012
Author(s):  
Eugenе Sosenushkin ◽  
Oksana Ivanova ◽  
Elena Yanovskaya ◽  
Yuliya Vinogradova
Keyword(s):  
Composite Materials ◽  
Friction Force ◽  
Equations Of Motion ◽  
Elastic Fiber ◽  
Dynamic Loads ◽  
Friction Forces ◽  
Absolute Value ◽  
A Value ◽  
The Absolute ◽  
The Impact

In this paper, we study the dynamic processes in materials reinforced with fibers, that can be represented as composite rods. There has been developed a mathematical model of wave propagation under the impact of a shock pulse in semi-infinite composite rods. It is believed that the considered composite rod consists of two layers formed by simpler rods of different isotropic materials with different mechanical properties. The cross sections of such rods are considered to be constant and identical. When such composite materials are impacted by dynamic loads, a significant part of the energy is dissipated due to the presence of friction forces between the contact surfaces of the rods. In this regard, we study the propagation of waves in an elastic fiber-rod, the layers of which interact according to Coulomb law of dry friction. The case of instantaneous excitation of rods by step pulses is investigated. The blow is applied to a rod made of a harder material. In the absence of slippage, the friction force gets a value not exceeding the absolute value of the limit. In the absence of slippage, the friction force takes a value not exceeding the absolute value of the limit. Let us consider the value of the friction force constant. Normal stresses and velocities satisfy the equations of motion and Hooke’s law. The problem statement results in the solution of inhomogeneous wave equations by the method of characteristics in different domains, which are the lines of discontinuities of the solution. Solutions are found in all constructed domains. On the basis of the analysis of the obtained solution, qualitative conclusions are made and curves are constructed according to the obtained ratios. From the found analytical solution of the problem it is possible to obtain ratios for stresses and strain rates in composite rods and composite materials.

Modeling Impacts Between a Continuous System and a Rigid Obstacle Using Coefficient of Restitution

2009 ◽  
Vol 77 (2) ◽  
Author(s):  
Chandrika P. Vyasarayani ◽  
John McPhee ◽  
Stephen Birkett
Keyword(s):  
Initial Conditions ◽  
Equations Of Motion ◽  
Continuous System ◽  
Coefficient Of Restitution ◽  
Continuous Systems ◽  
Rigid Obstacle ◽  
Unit Impulse ◽  
Before And After ◽  
System Equations ◽  
The Impact

In this work, we discuss the limitations of the existing collocation-based coefficient of restitution method for simulating impacts in continuous systems. We propose a new method for modeling the impact dynamics of continuous systems based on the unit impulse response. The developed method allows one to relate modal velocity initial conditions before and after impact without requiring the integration of the system equations of motion during impact. The proposed method has been used to model the impact of a pinned-pinned beam with a rigid obstacle. Numerical simulations are presented to illustrate the inability of the collocation-based coefficient of restitution method to predict an accurate and energy-consistent response. We also compare the results obtained by unit impulse-based coefficient of restitution method with a penalty approach.

A Numerical Method for Multibody System Frictional Impact Simulation

2001 ◽  
Author(s):  
Evtim V. Zakhariev
Keyword(s):  
Multibody Systems ◽  
Contact Point ◽  
Coefficient Of Restitution ◽  
Dynamics Modeling ◽  
Tangential Plane ◽  
Impact Process ◽  
Impact Theory ◽  
Rigid Multibody Systems ◽  
Two Stages ◽  
The Impact

Abstract In the paper a numerical algorithm for modeling of impact of rigid and flexible multibody systems considering the nonlinear Coulomb friction is presented. The algorithm is developed on the basis of the kinematic decomposition of the contacting surfaces. The possible motion along the normal direction of the contact point tangential plane is considered generalized coordinate. The impulse-momentum equations are derived using a general algorithm for dynamics modeling and solved consequently for the two stages, compression and restitution, of the impact process. Rigid body impact theory and analysis of the contacting point relative velocity are applied for effective modeling of the events sliding-stiction and reverse sliding. The method presented considers either Newton’s or Poisson’s hypothesis for the coefficient of restitution. The same approach is used for flexible systems that are discretized using finite element theory. It is pointed out that, if rigid multibody systems are considered, the coefficient of restitution does not reveal the true picture of the impact process. Several examples are solved and compared with the results obtained in other treatments.

Impact With Friction

1986 ◽  
Vol 53 (1) ◽  
pp. 1-4 ◽  
Author(s):  
J. B. Keller
Keyword(s):  
Frictional Force ◽  
Equations Of Motion ◽  
Coefficient Of Restitution ◽  
Rigid Bodies ◽  
The Impact ◽  
Impact With Friction

A theory of the impact or collision of two rigid bodies, taking account of friction, is presented. It determines how the direction of sliding varies during the impact, which must be known to calculate the direction of the frictional force and thence the frictional impulse. This is accomplished by analyzing the equations of motion of the bodies during the collision. The normal impulse is determined by using a coefficient of restitution. When the direction of sliding is constant throughout the collision, the theory agrees with that given by Whittaker, which is correct only in this case.

Differential Formulation for the Coefficient of Restitution of a Rigid Link

2015 ◽  
Vol 762 ◽  
pp. 175-182 ◽  
Author(s):  
Dorian Cojocaru ◽  
Dan B. Marghitu
Keyword(s):  
Mobile Robots ◽  
Initial Conditions ◽  
Equations Of Motion ◽  
Coefficient Of Restitution ◽  
Numerical Techniques ◽  
Differential Impact ◽  
Differential Formulation ◽  
Nonlinear Contact ◽  
Nonlinear Equations Of Motion ◽  
The Impact

The differential impact equations of motion are developed using an nonlinear contact force. The nonlinear equations of motion are written using symbolical MATLAB and are solved using numerical techniques. The impact equations are based on the Kogut-Etsion model. The numerical results are obtained for different geometries of the link, different coefficients of friction, and different initial conditions. The coefficient of restitution (COR) is discussed for specific cases. The results can be used for the impact of mobile robots with different type of surfaces.

scholarly journals Effect of Lipopolysaccharides (LPS) and Lipoteichoic acid (LTA) on the Inflammatory Response in Rumen Epithelial Cells (REC) and the Impact of LPS on Claw Explants

Animals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 2058
Author(s):  
Nicole Reisinger ◽  
Dominik Wendner ◽  
Nora Schauerhuber ◽  
Elisabeth Mayer
Keyword(s):  
Epithelial Cells ◽  
Inflammatory Response ◽  
Structural Integrity ◽  
Animal Health ◽  
Lipoteichoic Acid ◽  
Local Inflammatory Response ◽  
Tissue Integrity ◽  
Separation Force ◽  
The Impact ◽  
Rumen Epithelial Cells

Endotoxins play a crucial role in ruminant health due to their deleterious effects on animal health. The study aimed to evaluate whether LPS and LTA can induce an inflammatory response in rumen epithelial cells. For this purpose, epithelial cells isolated from rumen tissue (RECs) were stimulated with LPS and LTA for 1, 2, 4, and 24 h. Thereafter, the expression of selected genes of the LPS and LTA pathway and inflammatory response were evaluated. Furthermore, it was assessed whether LPS affects inflammatory response and structural integrity of claw explants. Therefore, claw explants were incubated with LPS for 4 h to assess the expression of selected genes and for 24 h to evaluate tissue integrity via separation force. LPS strongly affected the expression of genes related to inflammation (NFkB, TNF-α, IL1B, IL6, CXCL8, MMP9) in RECs. LTA induced a delayed and weaker inflammatory response than LPS. In claw explants, LPS affected tissue integrity, as there was a concentration-dependent decrease of separation force. Incubation time had a strong effect on inflammatory genes in claw explants. Our data suggest that endotoxins can induce a local inflammatory response in the rumen epithelium. Furthermore, translocation of LPS might negatively impact claw health.

scholarly journals The Effect of Superabsorbent Polymers on the Microstructure and Self-Healing Properties of Cementitious-Based Composite Materials

2021 ◽  
Vol 11 (2) ◽  
pp. 700
Author(s):  
Irene A. Kanellopoulou ◽  
Ioannis A. Kartsonakis ◽  
Costas A. Charitidis
Keyword(s):  
Mechanical Properties ◽  
Composite Materials ◽  
Hybrid Structure ◽  
The Self ◽  
Self Healing ◽  
Cementitious Composite ◽  
Superabsorbent Polymers ◽  
Porosity Reduction ◽  
Environment Control ◽  
The Impact

Cementitious structures have prevailed worldwide and are expected to exhibit further growth in the future. Nevertheless, cement cracking is an issue that needs to be addressed in order to enhance structure durability and sustainability especially when exposed to aggressive environments. The purpose of this work was to examine the impact of the Superabsorbent Polymers (SAPs) incorporation into cementitious composite materials (mortars) with respect to their structure (hybrid structure consisting of organic core—inorganic shell) and evaluate the microstructure and self-healing properties of the obtained mortars. The applied SAPs were tailored to maintain their functionality in the cementitious environment. Control and mortar/SAPs specimens with two different SAPs concentrations (1 and 2% bwoc) were molded and their mechanical properties were determined according to EN 196-1, while their microstructure and self-healing behavior were evaluated via microCT. Compressive strength, a key property for mortars, which often degrades with SAPs incorporation, in this work, practically remained intact for all specimens. This is coherent with the porosity reduction and the narrower range of pore size distribution for the mortar/SAPs specimens as determined via microCT. Moreover, the self-healing behavior of mortar-SAPs specimens was enhanced up to 60% compared to control specimens. Conclusively, the overall SAPs functionality in cementitious-based materials was optimized.

scholarly journals Towards Transabdominal Functional Photoacoustic Imaging of the Placenta: Improvement in Imaging Depth Through Optimization of Light Delivery

2021 ◽  
Author(s):  
Kristie Huda ◽  
Kenneth F. Swan ◽  
Cecilia T. Gambala ◽  
Gabriella C. Pridjian ◽  
Carolyn L. Bayer
Keyword(s):  
Delivery System ◽  
Light Propagation ◽  
Ex Vivo ◽  
Photoacoustic Imaging ◽  
Incidence Angle ◽  
Incident Angle ◽  
Placental Tissue ◽  
Light Delivery ◽  
Imaging Depth ◽  
The Impact

AbstractFunctional photoacoustic imaging of the placenta could provide an innovative tool to diagnose preeclampsia, monitor fetal growth restriction, and determine the developmental impacts of gestational diabetes. However, transabdominal photoacoustic imaging is limited in imaging depth due to the tissue’s scattering and absorption of light. The aim of this paper was to investigate the impact of geometry and wavelength on transabdominal light delivery. Our methods included the development of a multilayer model of the abdominal tissue and simulation of the light propagation using Monte Carlo methods. A bifurcated light source with varying incident angle of light, distance between light beams, and beam area was simulated to analyze the effect of light delivery geometry on the fluence distribution at depth. The impact of wavelength and the effects of variable thicknesses of adipose tissue and muscle were also studied. Our results showed that the beam area plays a major role in improving the delivery of light to deep tissue, in comparison to light incidence angle or distance between the bifurcated fibers. Longer wavelengths, with incident fluence at the maximum permissible exposure limit, also increases fluence within deeper tissue. We validated our simulations using a commercially available light delivery system and ex vivo human placental tissue. Additionally, we compared our optimized light delivery to a commercially available light delivery system, and conclude that our optimized geometry could improve imaging depth more than 1.6×, bringing the imaging depth to within the needed range for transabdominal imaging of the human placenta.

scholarly journals Effect of ball collision direction on a wet mechanochemical reaction

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Takahiro Kozawa ◽  
Kayo Fukuyama ◽  
Kizuku Kushimoto ◽  
Shingo Ishihara ◽  
Junya Kano ◽  
...  
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Reaction Rates ◽  
Tangential Component ◽  
Normal Direction ◽  
Mechanochemical Reaction ◽  
Precipitation Mechanism ◽  
The Impact ◽  
Mechanochemical Reactions ◽  
Ball Motion

AbstractMechanochemical reactions can be induced in a solution by the collision of balls to produce high-temperature and high-pressure zones, with the reactions occurring through a dissolution–precipitation mechanism due to a change in solubility. However, only a fraction of the impact energy contributes to the mechanochemical reactions, while the rest is mainly consumed by the wear of balls and the heat generation. To clarify whether the normal or tangential component of collisions makes a larger contribution on the reaction, herein we studied the effect of collision direction on a wet mechanochemical reaction through combined analysis of the experimental reaction rates and simulated ball motion. Collisions of balls in the normal direction were found to contribute strongly to the wet mechanochemical reaction. These results could be used to improve the synthesis efficiency, predict the reaction, and lower the wear in the wet mechanochemical reactions.

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