Wyniki wyszukiwania - BazTech

1

Calculation of maximal collision force in kinematic chains based on collision force impulse

Warzecha Mariusz, Michalczyk Jerzy

Journal of Theoretical and Applied Mechanics

|

2020

|

Vol. 58 nr 2

339--349

EN

This paper presents a new method for calculating maximal collision forces in kinematic chains based on their impulses. Its main advantage is its simplicity as it is based on algebraic equations. Collisions between the feed, hammer and rotor in a hammer crusher are used as a case study to show the implementation of the proposed method. The obtained results are then compared with a reference time-domain model. The proposed method can be used by mechanical engineers in early design phases to estimate loads acting on parts during collisions as well as to search for more optimal geometrical parameters.

2

Collision modeling of single unit impact absorber for mechanical systems vibration attenuation

Chehaibi Kaouther, Mrad Charfeddine, Nasri Rachid

Journal of Theoretical and Applied Mechanics

|

2019

|

Vol. 57 nr 4

947--956

EN

A single unit impact absorber is a ball absorber located in a mechanical system to attenuate its undesirable vibration. The absorber has a free motion constrained by stops. Collisions between the main system and the absorber masses help to dissipate kinetic energy as heat, noise and high frequency vibrations and thus reducing the main system dynamic response. However, the collisions give rise to discontinuity and strong nonlinearity. This work intends to study the effect of the collision modeling on the absorber efficiency. The contact force-based linear viscoelastic model of Hook-Newton, nonlinear elastic model of Hertz, and nonlinear viscoelastic model proposed by Hunt and Crossley are considered. For each case, analytical study is conducted to determine the equations of motion. The system responses are obtained for forced vibration, considering the whole ball motion cycle: left impact-free motion-right impact and following a numerical resolution based on the Newmark method. Finally, comparison of different impact models is made to conclude on the single unit impact absorber performance.

3

Wybrane aspekty analizy i modelowania zderzenia samochodów

Kisilowski J., Zalewski J.

TTS Technika Transportu Szynowego

|

2013

|

R. 20, nr 10

575--589, CD

PL

W artykule przeprowadzono analizę niektórych aspektów modelowania zderzenia samochodów z uwzględnieniem wybranych czynników wpływających na jego przebieg. Klasyczne podejście do zderzenia ciał zaadaptowano do problemu kolizji samochodów, prowadząc ogólną analizę złożoności tego zagadnienia. Prócz uwzględnienia szorstkości powierzchni zderzających się pojazdów rozważono także występowanie dodatkowych, zewnętrznych sił impulsowych działających na układ pojazdów będących w kontakcie. Ponadto, prócz ruchu płaskiego, uwzględniono także ruch złożony (siła bezwładności, unoszenia i Coriolisa). Dokonano analizy dotyczącej możliwości oraz konieczności uwzględnienia wybranych parametrów w modelowaniu zderzeń samochodów.

EN

In the paper analysis of certain aspects of collision between motor vehicles modelling is presented including selected factors influencing its course. The classic approach towards the crash of mechanical bodies was adapted to the problem of the collision between vehicles, as the general analysis of complexity of this issue was conducted. Apart from taking the roughness of the surface of crashing vehicles into account, the occurrence of additional, external impulse forces acting on the set of vehicles being in contact was also assumed. Moreover, apart from the plane motion, also a resultant motion of each vehicle during the crash was included (forces of inertia and transportation as well as Coriolis force). Analysis was made concerning the possibility and necessity to take the selected parameters into account in modelling of collisions between vehicles.