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 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 Analytical Study of Babbitt/steel Composite Structural Bars in Oblique Contact-impact with a Solid Flat Surface

2019 ◽  
Vol 10 (1) ◽  
pp. 213-228 ◽  
Author(s):  
Yao Wang ◽  
Zhuang Fu
Keyword(s):  
Angular Velocity ◽  
Contact Force ◽  
Flat Surface ◽  
Permanent Deformation ◽  
Coefficient Of Restitution ◽  
Contact Forces ◽  
Experimental Results ◽  
Impact Behavior ◽  
Contact Impact ◽  
Weak Material

Abstract. The oblique contact-impact characteristic of the composite structural bar composed of Babbitt alloy and low-carbon steel (ZChSbSb11-6 ∕ AISI 1020) with a solid flat surface (AISI 1045) was studied theoretically and experimentally. The dynamic equation of the composite structural bar with vibration response during the contact-impact was established using the momentum theorem and assumed mode method, and the instantaneous contact forces during different impact phases were analyzed based on modified Jackson–Green model. Four sets of experiments (i.e. different proportion of Babbitt, ξ={1/8,1/2,3/4,7/8}) for the initial angle, θ=45∘, and different initial velocities were performed; and, the rebound linear and angular velocity of the contact point of composite structural bar after impact was calculated and compared with experimental results. Besides, the coefficient of restitution, the relation of contact force and contact deflection, and the permanent deformation were also compared for the composite structural bars with different proportions in combination, ξ. Three critical angles are found to determine whether the composite bar slides or not, but are prominently different for the composite bars with different ξ. In comparing with the experimental results, the numerical solutions of rebound linear and angular velocity had yield encourage results and, all relative errors were small, indicating that the simulations are in good agreement with the experimental results. Also, the oblique contact-impact behavior involving the coefficient of restitution, the relation of contact force and contact deflection, and the permanent deformation was explained in detail. It can be concluded that as the proportion of Babbitt ξ increases, the composite structural bar presents a characteristic of ease of deflection. And the contact-impact behavior of structural entity is closely related to the inherent properties of the elasto-plastic material, especially for the weak material of composite structures. The more easily the impacting object is deformed, the small the contact force during the contact-impact, which also indicates the yield strength of weak material is a very significant parameter in the event of collision. Such work could give conducive insights to contact-impact problems of the key parts or structures composed of composite materials in mechanical system.

scholarly journals Study on the Failure of the Bolted Flange Connection Structure between Stages of Missiles (Rockets) under Transverse Impact Load

2018 ◽  
Vol 2018 ◽  
pp. 1-16
Author(s):  
Tonghui Tian ◽  
Jiehong Yuan ◽  
Daokui Li ◽  
Qingwen Wang ◽  
Baisheng Chen
Keyword(s):  
Impact Force ◽  
Impact Load ◽  
Failure Process ◽  
Element Model ◽  
Experimental Results ◽  
Transverse Impact ◽  
Flange Connection ◽  
Response Data ◽  
Bolted Flange ◽  
The Impact

Based on the bolted flange connection structure between stages of the missiles, four experimental specimens are simplified and manufactured, and the transverse impact failure experiments of the drop hammer are designed and carried out in this study. During the experiments, a new signal sensor is designed to collect the data of the bolts force, and the response data such as the bolts force, the slotted displacement of the connecting interface, and the impact force are collected in the loading process. The sequential failure mechanism of the structure under transverse impact load is analyzed and demonstrated according to the experimental results and the measured data. Additionally, a finite element model to simulate the failure process of the connection structure has been established, and the precision of the model has been verified and validated according to the experimental results. Moreover, the comparison between the results of the experiments and the simulation shows that the precision of this model is reliable in the engineering.

Analytical Study of the Oblique Impact of a Rod with a Flat Using an Elasto-Plastic Contact Model

2015 ◽  
Vol 801 ◽  
pp. 25-32
Author(s):  
Ozdes Cermik ◽  
Hamid Ghaednia ◽  
Dan B. Marghitu
Keyword(s):  
Impact Velocity ◽  
Contact Force ◽  
Analytical Study ◽  
Initial Conditions ◽  
Permanent Deformation ◽  
Oblique Impact ◽  
Coefficient Of Restitution ◽  
Contact Model ◽  
Impact Angles ◽  
The Impact

In the current study a flattening contact model, combined with a permanent deformation expression, has been analyzed for the oblique impact case. The model has been simulated for different initial conditions using MATLAB. The initial impact velocity used for the simulations ranges from 0.5 to 3 m/s. The results are compared theoretically for four different impact angles including 20, 45, 70, and 90 degrees. The contact force, the linear and the angular motion, the permanent deformation, and the coefficient of restitution have been analyzed. It is assumed that sliding occurs throughout the impact.

scholarly journals Research and Improvement of the Hydraulic Suspension System for a Heavy Hydraulic Transport Vehicle

2020 ◽  
Vol 10 (15) ◽  
pp. 5220 ◽  
Author(s):  
Jianjun Wang ◽  
Jingyi Zhao ◽  
Wenlei Li ◽  
Xing Jia ◽  
Peng Wei
Keyword(s):  
Mathematical Model ◽  
Nonlinear System ◽  
Ride Comfort ◽  
Impact Force ◽  
Suspension System ◽  
Experimental Results ◽  
Hydraulic Transport ◽  
Transport Vehicle ◽  
Set Up ◽  
The Impact

In order to ensure the ride comfort of a hydraulic transport vehicle in transportation, it is important to account for the effects of the suspension system. In this paper, an improved hydraulic suspension system based on a reasonable setting of the accumulator was proposed for a heavy hydraulic transport vehicle. The hydraulic transport vehicle was a multi-degree nonlinear system, and the establishment of an appropriate vehicle dynamical model was the basis for the improvement of the hydraulic suspension system. The hydraulic suspension system was analyzed, and a mathematical model of the hydraulic suspension system with accumulator established and then analyzed. The results revealed that installing the appropriate accumulator can absorb the impact pressure on the vehicle, while a hydraulic suspension system with an accumulator can be designed. Further, it was proved that a reasonable setting for the accumulator can reduce the impact force on the transport vehicle through simulation, and the optimal accumulator parameters can be obtained. Finally, an experiment in the field was set up and carried out, and the experimental results presented to prove the viability of the proposed method.

scholarly journals Optimal damping coefficient for a class of continuous contact models

2020 ◽  
Vol 50 (2) ◽  
pp. 169-188
Author(s):  
Mohammad Poursina ◽  
Parviz E. Nikravesh
Keyword(s):  
Contact Force ◽  
Analytical Formula ◽  
Coefficient Of Restitution ◽  
Damping Coefficient ◽  
Optimization Strategy ◽  
Continuous Contact ◽  
Optimal Damping ◽  
Wide Range ◽  
Contact Models ◽  
The Impact

Abstract In this study, we develop an analytical formula to approximate the damping coefficient as a function of the coefficient of restitution for a class of continuous contact models. The contact force is generated by a logical point-to-point force element consisting of a linear damper connected in parallel to a spring with Hertz force–penetration characteristic, while the exponent of deformation of the Hertz spring can vary between one and two. In this nonlinear model, it is assumed that the bodies start to separate when the contact force becomes zero. After separation, either the restitution continues or a permanent penetration is achieved. Therefore, this model is capable of addressing a wide range of impact problems. Herein, we apply an optimization strategy on the solution of the equations governing the dynamics of the penetration, ensuring that the desired restitution is reproduced at the time of separation. Furthermore, based on the results of the optimization process along with analytical investigations, the resulting optimal damping coefficient is analytically expressed at the time of impact in terms of system properties such as the effective mass, penetration velocity just before the impact, coefficient of restitution, and the characteristics of the Hertz spring model.

scholarly journals The Effect of the Contact Model on the Design of Mechanical Systems

2012 ◽  
Author(s):  
M. R. Brake ◽  
D. S. Aragon ◽  
D. J. VanGoethem ◽  
H. Sumali
Keyword(s):  
Constant Coefficient ◽  
Degrees Of Freedom ◽  
Mechanical Systems ◽  
Constitutive Models ◽  
Coefficient Of Restitution ◽  
Rigid Body Dynamics ◽  
Contact Model ◽  
Elastic Plastic ◽  
Contact Models ◽  
The Impact

Impact is a wide-spread phenomenon in mechanical systems that can have a significant effect on the system’s dynamics, stability, wear, and damage. The simulation of impact in complex, mechanical systems, however, is often too computationally intensive for high fidelity finite element analyses to be useful as design tools. As a result, rigid body dynamics and reduced order model simulations are often used, with the impact events modeled by ad hoc methods such as a constant coefficient of restitution or a penalty stiffness. The consequences of the choice of contact model are studied in this paper for a representative multiple-degrees of freedom mechanical system. Four contact models are considered in the analysis: a constant coefficient of restitution model, two similar elastic-plastic constitutive models, and one dissimilar elastic-plastic constitutive model. The predictions of wear, mechanical failure, and stability are assessed for each of the contact models, and the subsequent effect on the system design is investigated. These results emphasize the importance of choosing a realistic contact model when simulations are being used to drive the design of a system.

The Efficacy of Impact-Absorbing Materials during Collision with a Soccer Ball

2013 ◽  
Vol 440 ◽  
pp. 363-368
Author(s):  
Zahari Taha ◽  
Mohd Hasnun Arif Hassan ◽  
Mohd Azri Aris
Keyword(s):  
High Speed ◽  
Impact Force ◽  
Coefficient Of Restitution ◽  
Soccer Ball ◽  
Absorbing Materials ◽  
The Subject ◽  
The Impact ◽  
The Brain ◽  
Peak Impact Force ◽  
Impact Duration

The uniqueness of soccer is that the players are allowed to use their head to pass the ball to a teammate of even try to score goal. Studies have shown that heading in soccer might be dangerous to the brain and could lead to brain trauma. There are headgears available for soccer players to protect their head, but studies have proven that currently available headgears are ineffective in reducing the impact caused by a soccer ball. The objective of this study is to test the efficacy of six different types of impact-absorbing materials in reducing the linear impact force from a soccer ball. The soccer ball was dropped from the height of 2.3 m onto a force platform to measure the impact force. A high-speed camera is used to record the motion and the impact duration, and then the coefficient of restitution for each impact was determined. Polyurethane (PU) comb-gel was found to be the most effective material in reducing the peak impact force and impulse compared with other materials. The reduction in peak force was associated with longer impact duration between the soccer ball and the PU comb-gel. However, the coefficient of restitution was reduced by 21.7%, implying that using the gel alone will reduce the speed of the ball after heading, thus reducing the performance of a player wearing it. A combination of PU gel and another stiffer material is suggested and the effectiveness of the composite will be the subject of future investigation.

scholarly journals Numerical and Experimental Results on Charpy Tests for Blends Polypropylene + Polyamide + Ethylene Propylene Diene Monomer (PP+PA+EDPM)

2020 ◽  
Author(s):  
Catalin Pirvu ◽  
Andreea Elena Musteata ◽  
George Ghiocel Ojoc ◽  
Lorena Deleanu
Keyword(s):  
Equivalent Plastic Strain ◽  
Material Model ◽  
Element Model ◽  
Tensile Tests ◽  
Experimental Results ◽  
Low Velocity ◽  
Sem Images ◽  
Charpy Test ◽  
Simulation Results ◽  
The Impact

This paper presents results from numerical and experimental investigation on Charpy tests in order to point out failure mechanisms and to evaluate new polymeric blends PP+PA6+EPDM. Charpy tests were done for initial velocity of the impactor of 0.96 m/s and its mass of 3.219 kg and these data were also introduced in the finite element model. The proposed model take into account the system of four balls, including support and the ring of fixing the three balls and it has a finer discretization of the impact area to highlight the mechanisms of failure and their development in time. The constitutive models for four materials (polypropylene with 1% Kritilen, two blends PP+PA6+EPDM and a blend PA6+EPDM) were derived from tensile tests. Running simulations for each constitutive model of material makes possible to differentiate the destruction mechanisms according to the material introduced in the simulation, including the initiation and the development of the crack(s), based on equivalent plastic strain at break (EPS) for each material. The validation of the model and the simulation results was done qualitatively, analysing the shape of broken surfaces and comparing them to SEM images and quantitatively by comparing the impact duration, energy absorbed by the sample, the value of maximum force during impact. The duration of the destruction of the specimen is longer than the actual one, explainable by the fact that the material model does not take into account the influence of the material deformation speed in Charpy test, the model being designed with the help of tests done at 0.016 m/s (1000 mm/min) (maximum strain rate for the tensile tests). Experimental results are encouraging for recommending the blends 20% PP+42% PA6+28% EPDM and 60% PA6+ 40%EPDM as materials for impact protection at low velocity (1m/s). Simulation results are closer to the experimental ones for the more brittle tested materials (with less content of PA6 and EPDM) and more distanced for the more ductile materials (with higher content of PA6 and EPDM).

scholarly journals Numerical Investigation on Dynamic Response of RC T-Beams Strengthened with CFRP under Impact Loading

Crystals ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 890
Author(s):  
Huiling Zhao ◽  
Xiangqing Kong ◽  
Ying Fu ◽  
Yihan Gu ◽  
Xuezhi Wang
Keyword(s):  
Numerical Simulation ◽  
Impact Force ◽  
Reaction Force ◽  
Impact Resistance ◽  
Structural Response ◽  
Element Model ◽  
Strengthening Effect ◽  
Strengthened Beam ◽  
Simulation Results ◽  
The Impact

To precisely evaluate the retrofitting effectiveness of Carbon Fiber Reinforced Plastic (CFRP) sheets on the impact response of reinforced concrete (RC) T-beams, a non-linear finite element model was developed to simulate the structural response of T-beams with CFRP under impact loads. The numerical model was firstly verified by comparing the numerical simulation results with the experimental data, i.e., impact force, reaction force, and mid-span displacement. The strengthening effect of CFRP was analyzed from the section damage evaluation. Then the impact force, mid-span displacement, and failure mode of CFRP-strengthened RC T-beams were studied in comparison with those of un-strengthened T-beams. In addition, the influence of the impact resistance of T-beams strengthened with FRP was investigated in terms of CFRP strengthening mode, CFRP strengthening sizes, CFRP layers and FRP material types. The numerical simulation results indicate that the overall stiffness of the T-beams was improved significantly due to external CFRP strips. Compared with the un-strengthened beam, the maximum mid-span displacement of the CFRP-strengthened beam was reduced by 7.9%. Additionally, the sectional damage factors of the whole span of the CFRP-strengthened beam were reduced to less than 0.3, indicating that the impact resistance of the T-beams was effectively enhanced.

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