Control of machines with non-linear, low-velocity friction: A dimensional analysis

2006 ◽  
pp. 180-195 ◽  
Author(s):  
Brian S. R. Armstrong
Keyword(s):  
Dimensional Analysis ◽  
Low Velocity ◽  
Non Linear

Experimental and Numerical Investigation of Response of Sandwich Composite Beam Subjected to Low-Velocity Impact

2015 ◽  
Vol 732 ◽  
pp. 239-246 ◽  
Author(s):  
Tomáš Mandys ◽  
Vladislav Laš ◽  
Tomáš Kroupa ◽  
Robert Zemčík
Keyword(s):  
Composite Beam ◽  
Progressive Failure ◽  
Material Model ◽  
Low Velocity Impact ◽  
Elastic Behavior ◽  
Sandwich Composite ◽  
Low Velocity ◽  
Velocity Impact ◽  
Non Linear ◽  
Force Time

This paper deals with the progressive failure analysis of sandwich composite beam loaded with transversely low-velocity impact. A user defined material model was used for modeling of the non-linear orthotropic elastic behavior of composite skin. The non-linear behavior of foam core was modeled using Low-Density Foam material model. The numerical model was validated using performed experiment and the results in terms of deflection and contact force time dependencies are mutually compared.

Non-linear dynamics of a simply supported fluid-conveying pipe subjected to motion-limiting constraints: Two-dimensional analysis

2018 ◽  
Vol 435 ◽  
pp. 192-204 ◽  
Author(s):  
Geng Peng ◽  
Youming Xiong ◽  
Yun Gao ◽  
Liming Liu ◽  
Menghao Wang ◽  
...  
Keyword(s):  
Dimensional Analysis ◽  
Two Dimensional ◽  
Linear Dynamics ◽  
Simply Supported ◽  
Non Linear

scholarly journals Collisions of supersonic clouds

2010 ◽  
Vol 6 (S270) ◽  
pp. 355-358
Author(s):  
Andrew McLeod ◽  
Jan Palouš ◽  
Anthony Whitworth
Keyword(s):  
High Velocity ◽  
Thin Shell ◽  
Molecular Clouds ◽  
Energy Equation ◽  
Low Velocity ◽  
Heating And Cooling ◽  
Non Linear ◽  
Compressed Layer

AbstractWe present simulations of supersonic collisions between molecular clouds of mass 500 M⊙ and radius 2.24 pc. The simulations are performed with the SEREN SPH code. The code treats the energy equation and the associated transport of heating and cooling radiation. The formation of protostars is captured by introducing sink particles. Low velocity collisions form a shock-compressed layer which fragments to form stars. For high-velocity collisions, υrel ⪆ 5 km s−1, the non-linear thin shell instability strongly disrupts the shock-compressed layer, and may inhibit the formation of stars.

Effects of the impactor geometrical shape on the non-linear low-velocity impact response of sandwich plate with CNTRC face sheets

2018 ◽  
Vol 22 (4) ◽  
pp. 962-990 ◽  
Author(s):  
A Khalkhali ◽  
N Geran Malek ◽  
M Bozorgi Nejad
Keyword(s):  
Contact Force ◽  
Sandwich Plate ◽  
Impact Response ◽  
Low Velocity Impact ◽  
Integration Scheme ◽  
Geometrical Shape ◽  
Low Velocity ◽  
Velocity Impact ◽  
Non Linear ◽  
Central Displacement

In this study, non-linear low-velocity impact response of a simply supported sandwich plate with CNTRC face sheets subjected to the impactors with different geometrical shapes is investigated. It has been assumed that the sandwich plate is made up of two face sheets reinforced with CNTs graded along their thickness as X profile and a homogeneous core. In CNT-reinforced layers, a micromechanical model has been used to obtain the effective material properties and the analysis is performed in the framework of the Reddy's higher order shear deformation theory with regard to thermal effects. An analytical model is proposed to capture the response performance of the three-layer sandwich plates under different thermal environments. Through the proposed analytical study, in order to characterize the contact force between the sandwich plate and the impactors, the modified Hertz contact law is utilized. Rayleigh-Ritz method is applied to the Hamilton principle in order to find the set of equations of motion for the impactor as well as the CNTRC sandwich plate. Afterwards, the solution in the time domain is obtained based on Newmark's numerical time integration scheme. After validating the proposed approach, in order to examine the influences of various involved parameters, different parametric studies are conducted. It has been demonstrated that the variation of the initial kinetic energy as one of the parameters under study has a significant effect on the central displacement, contact force, and indentation in both conical and cylindrical impactors and the change in the radius of the cylinder has an insignificant effect on the central displacement. As well, in the case of equal masses, the cylindrical impactor causes more amount of indentation with respect to conical.

Draft System for Enhanced Impact Protection and Train Action Control: Validation by Testing and Computer Modeling

2001 ◽  
Author(s):  
Marlin E. Clark
Keyword(s):  
Computer Modeling ◽  
Action Control ◽  
Low Velocity ◽  
Spring Rate ◽  
Force Transfer ◽  
Non Linear ◽  
Draft Gear ◽  
Linear Spring ◽  
Dynamic Braking ◽  
New Applications

Abstract Certain types of freight cars that are normally equipped with conventional draft gears to protect car structure from coupling impact forces can benefit from additional buff travel. This reduces the coupler force experienced by the car structure; limiting the potential for structural and fatigue damage and improving wear characteristics. This can be accomplished within the standard draft pocket dimensions, allowing for improvements in both retrofit and new applications. Impact test data will show reductions in coupler force as compared to conventional draft gear systems under identical impact conditions. With additional buff travel available, greater protection is afforded against encounters with higher speed impacts. Train action control can be enhanced through the application of an elastomeric spring with a stiffer non-linear spring rate. Conventional draft systems use a yoke around the draft gear, permitting the full travel of the device in both the draft and buff modes. The free slack transversed in reversal from buff to draft mode, followed by the relatively soft spring rate of a conventional draft gear, especially at low velocity, can result in over-solid conditions and high force peaks. Car separation and car closure velocities are typically low, such as two miles per hour, so the effect of softer spring rate can be detrimental. The stiffer non-linear spring rate offers improved force transfer through each car as the force wave propagates through the train; the gradual and simultaneous buildup of force at each end of the car reduces relative car velocities and thus the severity of force transfer through each coupled connection. The elimination of a mechanical oversolid stop, replaced by the elastomeric spring, as it becomes stiffer with travel, also limits the end force experienced by the freight car structure. Computer modeling will show the advantages of this system during severe transient events, such as train startups and dynamic braking.

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