Vibrations due to Impact in a Non Ideal Mechanical System With a Non-Linear Hertzian Contact Model

2014 ◽  
Author(s):  
Helio A. Navarro ◽  
Jose M. Balthazar ◽  
Reyolando M. L. R. F. Brasil
Keyword(s):  
Mechanical System ◽  
Rigid Wall ◽  
Contact Forces ◽  
Hertzian Contact ◽  
Impact Behavior ◽  
Steady State Responses ◽  
Post Impact ◽  
The Impact ◽  
The Mathematical Model ◽  
State Responses

This work analyses the post impact behavior of a mechanical system consisting of an oscillator and an unbalanced non–ideal electrical motor. The impact between the mechanical system and a rigid wall is based on the assumption that the impacting bodies undergo local deformations. The method used in the present work is similar to the Discrete Element Method for particle systems modeled with a “soft–sphere” mechanism. The contact forces are modeled using a nonlinear damped Hertzian Spring-Dashpot system. The mathematical model of the mechanical system is represented by a set of nonlinear ordinary differential equations. The transient and steady-state responses are discussed. As the motor is considered a non ideal energy source, the Sommerfeld effect is also analyzed. The impact model is first applied for a single freely falling particle and then in the proposed mechanical system. Non-dimensional expressions for the contact force and numerical simulations of the mechanical system behavior are also presented.

scholarly journals Impact Behavior of a Rotating Rigid Body with Impact and Viscous Friction

2020 ◽  
Vol 2020 ◽  
pp. 1-11 ◽  
Author(s):  
Dorian Cojocaru ◽  
Dan B. Marghitu
Keyword(s):  
Viscous Friction ◽  
Friction Model ◽  
Contact Forces ◽  
Hertzian Contact ◽  
Impact Behavior ◽  
Element Analysis ◽  
Friction Parameters ◽  
Friction Function ◽  
Coulomb Dry Friction ◽  
The Impact

The impact between a rotating link and a solid flat surface is considered. For the impact, we consider three distinct periods: elastic period, elastoplastic period, and restitution period. A Hertzian contact force is considered for the elastic period. Nonlinear contact forces developed from finite element analysis are used for the remaining two phases. The tangential effect is taken into account considering a friction force that combines the Coulomb dry friction model and a viscous friction function of velocity. Simulations results are obtained for different friction parameters. An experimental setup was designed to measure the contact time during impact. The experimental and simulation results are compared for different lengths of the link.

Resolving the Unique Invariant Slip-Direction in Rigid Three-Dimensional Multi-Point Impacts at Stick-Slip Transitions

2018 ◽  
Author(s):  
Abhishek Chatterjee ◽  
Alan Bowling
Keyword(s):  
Single Point ◽  
Three Dimensional ◽  
Impact Behavior ◽  
Slip Direction ◽  
Stick Slip ◽  
Impact Forces ◽  
Post Impact ◽  
Impact Problems ◽  
Slip Transition ◽  
The Impact

This work presents a new approach for resolving the unique invariant slip direction at Stick-Slip Transition during impact. The solution method presented in this work is applicable to both single-point and multi-point impact problems. The proposed method utilizes rigid body constraints to resolve the impact forces at all collision points in terms of a single independent impact forces parameter. This work also uses an energetic coefficient of restitution to terminate impact events, thereby yielding energetically consistent post-impact behavior.

scholarly journals Effect of In-Situ Synthesized Boride Phases on the Impact Behavior of Iron-Based Composites Reinforced by B4C Particles

Metals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 554
Author(s):  
Fehmi Nair ◽  
Mustafa Hamamcı
Keyword(s):  
Contact Forces ◽  
Impact Behavior ◽  
Iron Matrix ◽  
Impact Tests ◽  
B4c Particles ◽  
Iron Based ◽  
In Situ Reactions ◽  
Boride Phases ◽  
The Impact

The objective of this study is to investigate the impact behavior of iron-based composites reinforced with boron carbide (B4C) particles and in-situ synthesized iron borides (Fe2B/FeB). The composite specimens (Fe/B4C) were fabricated by hot-pressing under a pressure of 250 MPa at 500 °C, and sintered at a temperature of 1000 °C. The effects of the reinforcement ratio on the formation of in-situ borides and impact behavior were investigated by means of different volume fractions of B4C inside the iron matrix: 0% (un-reinforced), 5%, 10%, 20%, and 30%. Drop-weight impact tests were performed by an instrumented Charpy impactor on reinforced and un-reinforced test specimens. The results of the impact tests were supported with microstructural and fractographical analysis. As a result of in-situ reactions between the Fe matrix and B4C particles, Fe2B phases were formed in the iron matrix. The iron borides, formed in the iron matrix during sintering, heavily affected the hardness and the morphology of the fractured surface. Due to the high amount of B4C (over 10%), porosity played a major role in decreasing the contact forces and fracture energy. The results showed that the in-situ synthesized iron boride phases affect the impact properties of the Fe/B4C composites.

The Structural Impact Characteristics of Indonesian Railway Vehicle

2004 ◽  
Vol 261-263 ◽  
pp. 337-344 ◽  
Author(s):  
Ign Wiratmaja Puja ◽  
T. Hardono ◽  
Khalid ◽  
M.F. Adziman
Keyword(s):  
Impact Energy ◽  
Impact Load ◽  
Rigid Wall ◽  
Impact Behavior ◽  
Railway Vehicle ◽  
Railway Transportation ◽  
Passenger Cars ◽  
Vehicle Structure ◽  
Structural Impact ◽  
The Impact

The Indonesian railway transportation has adventages in term of capacity, efficiency, trafic, and safety compared to the other types of land transportations. At present, the Indonesian Railway Company has 519 locomotives, and 1643 passenger cars, that transport about 184 million man-trip each year[1,2]. Unfortunately, the rate of train collisions in Indonesian railway system was very high. In the last ten years, 2352 train accidents have happened which claimed 997 lives and left 2638 people injured. The record shows that 110 of those accidents were train to train collisions[1]. This paper consider the structural impact behavior of Indonesian passenger railway car subject to collision forces. This characteristic is very important parameter for passenger protection during the course of collision[3-5]. The vehicle structure should be able to absorb the huge impact energy or impact force to ensure the passenger safety[6-9]. The impact energy of cars-train is evaluated using the principle of multibody dynamics[10,11]. The vehicle structure under impact load is analyzed using the finite element method. The principal of symmetry is adopted, so the collision scene could be simulated as collision between the vehicle with a rigid wall. The analysis result shows that the structure is collapse at the passenger area (saloon) which is in agreement with the real collision. Modification is proposed to protect the passenger area by introducing crush zone area and impact energy absorber.

Probabilistic Critical Safety Wheel Wear Sizes of Chinese Railway Freight Cars

2008 ◽  
Vol 44-46 ◽  
pp. 759-764
Author(s):  
Yong Xiang Zhao ◽  
Bing Yang ◽  
Ming Fei Feng ◽  
Y. Li ◽  
M.J. Liu ◽  
...  
Keyword(s):  
Field Investigation ◽  
State Equation ◽  
Contact Forces ◽  
Hertzian Contact ◽  
Wheel Wear ◽  
Size Change ◽  
Railway Freight ◽  
Impact Forces ◽  
Safety Effect ◽  
The Impact

Critical safety wheel wear size is investigated through considering the fatigue safety effect on RD2 type axle of China railway freight cars. The wheel wear size increase results in a rise of the wheel-rail contact forces, which increase the fatigue stress history of the axle in service. Therefore, the size must be controlled to maintain the axle safety in service before the next overhaul inspection. A field investigation was firstly made on the wear size change regularity. Then, the size related wheel-rail impact forces are solved by a non-linear Hertzian contact theory with a vehicle multi-body dynamic model. In addition, a statistical method is further developed for incorporating the impact forces into the wheelset service load history. Finally, a wear size related critical state equation is established for ensuring the axle safety in service. A stationary solution is statistically obtained for the critical wear sizes with respect to the axle circumferential crack and semi-elliptical crack. It is concluded that the critical safety wear size should be controlled in the range of 100 mm at the statistical level of survival probability 0.99 and confidence 95%.

Study of the Stick-Slip Transition of Newton’s Cradle With Friction

2013 ◽  
Author(s):  
Adrian Rodriguez ◽  
Alan Bowling
Keyword(s):  
Impact Behavior ◽  
Multiple Point ◽  
Stick Slip ◽  
Kinematic Relationship ◽  
Short Time Span ◽  
Post Impact ◽  
Newton’S Cradle ◽  
Six Degree Of Freedom ◽  
Slip Transition ◽  
The Impact

This work uses a new discrete approach to analyze the stick-slip transition of Newton’s cradle with frictional contact. The consideration of friction here leads to a simultaneous, multiple point, indeterminate collision. This work strictly adheres to the assumptions of rigid body modeling in conjunction with the notion that the configuration of the system are constant in the short time span of the collision, which enforces a kinematic relationship between the impact points. The post-impact velocities are determined by using the work-energy relationship of a collision and an energetic coefficient of restitution (ECOR) to model energy dissipation. A three and six degree-of-freedom (DOF) model of the system is considered in this work to examine the stick-slip transition and simulate the post-impact behavior. Simulations are conducted for each model using different coefficients of friction (COFs). The results obtained are compared to theoretical and experimental results reported in other works.

The Response of the QBO to Increases in CO2 Using Three Atmospheric Chemistry Configurations

2020 ◽  
Author(s):  
Kevin DallaSanta ◽  
Clara Orbe ◽  
Lorenzo Polvani
Keyword(s):  
Atmospheric Chemistry ◽  
Middle Atmosphere ◽  
Wave Drag ◽  
Cmip5 Models ◽  
Industrial Control ◽  
Quasi Biennial Oscillation ◽  
Steady State Responses ◽  
Goddard Institute ◽  
The Impact ◽  
State Responses

<p>Long-term projections of the Quasi-Biennial Oscillation (QBO) remain highly uncertain. This is partly due to the paucity of models which are able to properly simulate that phenomenon. Only 5 of the 47 CMIP5 models are capable of spontaneously generating a realistic QBO (Butchart et al., 2018), and even those models exhibit large biases in key QBO characteristics (e.g. amplitude, period, vertical extent) when compared with observations. Furthermore, only 1 of these 5 employed interactive atmospheric chemistry, which is known to modulate QBO dynamics.</p><p>We here investigate the QBO response to increased greenhouse gases using the NASA Goddard Institute for Space Studies Middle Atmosphere Model E2.2. Compared to lower vertical resolution versions of Model E, version 2.2 has a higher model top (0.002 hPa), and additional interactive non-orographic gravity wave drag sources from convection and shear, which produce a sufficiently realistic QBO, thus rendering it suitable for use in climate change studies. Steady-state responses to doubled and quadrupled CO<sub>2</sub><span> from </span>a pre-industrial control are analyzed, as well as the transient response to a 1% per year CO<sub>2</sub><span> </span>increase. In addition, we systematically explore the impact of interactive chemistry in modulating the QBO response to increased CO<sub>2</sub><span> by contrasting </span>interactive, prescribed, and linearized ozone chemistry configurations of the model. Overall, in response to increase CO<sub>2</sub> concentrations the QBO is seen to increase in frequency and weaken in amplitude, consistent with previous results, but the memory of the tropical stratosphere may complicate assessments of trends in chemistry and surface impacts. We also discuss implications for the trade-off between ensemble size and the complexity of the chemistry scheme in the model.</p>

scholarly journals Effect of Braiding Angle on the Impact and Post-Impact Behavior of 3D Braided Composites

2017 ◽  
Vol 49 (1) ◽  
pp. 198-205 ◽  
Author(s):  
S. Yan ◽  
L. Y. Guo ◽  
J. Y. Zhao ◽  
X. M. Lu ◽  
T. Zeng ◽  
...  
Keyword(s):  
Impact Behavior ◽  
Braided Composites ◽  
3D Braided Composites ◽  
Post Impact ◽  
Braiding Angle ◽  
The Impact
Sign in / Sign up

Export Citation Format

Share Document