|
|
Advanced Solution to Piston Assembly Dynamics
Dlugoš, Jozef ; Furch,, Jan (oponent) ; Kučera, Pavel (oponent) ; Novotný, Pavel (vedoucí práce)
The ultimate goal of this work is to develop an advanced computational model of piston assembly dynamics. The piston and the liner are interacting through the lubricant film or the surface asperities. This leads to different lubrication regimes and consequently different forces acting on the surfaces of the contact pair. During the solution to hydrodynamics and asperity contact forces, deformation of the piston and the liner has to be taken into account—the process is necessarily iterative in nature. Since the requirements for computational grid of the contact forces and of deformation differ, robust mapping algorithms are proposed. The results of the developed computational tool are experimentally verified. For this purpose, the measurement of the piston secondary motion by laser displacement sensors is conducted. The measurement is done on the experimental sidevalve engine with transparent cylinder head in order to generate compression pressure in the combustion chamber. Measured piston lateral motion is corrupted. Therefore, only measurement of the piston tilt angle is further used. The agreement of the measured and computed results varies during the operation cycle. Good agreement is achieved for compression and expansion strokes. Oppositely, significant differences occur when the side force is small: intake and exhaust strokes. Major contribution of this work is development of computational tool which implements the above mentioned effects that have a major impact on the piston assembly dynamics. Unfortunately, this leads to long computational times, especially when deformation is considered. For this reason, the parallel solution is developed. It is based on the parallelization of the subroutine during the evaluation of the sensibility analysis. This way, the solution time is reduced in order of magnitude.
|
|
|
Řešení příkladů mechaniky těles v ADAMS
Rybár, Šimon ; Švancara, Pavel (oponent) ; Hadaš, Zdeněk (vedoucí práce)
Cieľom tejto práce bolo vytvorenie parametrických modelov technických sústav v programe Adams. Pomocou simulácii boli sústavy skúmané z hľadiska kinematiky a dynamiky. V niekoľkých prípadoch boli výsledky simulácii porovnané s výsledkami získanými analytickou metódou. Práca je rozdelená do troch kapitol. V prvej je formulovaný problém a ciele práce. Druhá definuje multibody systém a bližšie predstavuje použitý program aj s jeho doplnkami. Tretia kapitola obsahuje päť typovo odlišných príkladov, na ktorých sú demonštrované možnosti Adamsu. V závere sú vypísané vlastné postrehy, celkové zhodnotenie a odporučenie pre potreby výuky.
|
|
| |
|
|
COMPUTER SIMULATION STUDY OF THE STABILITY OF UNDERACTUATED BIPEDAL ROBOT MODELS (motivated by Griffin and Grizzle, 2017)
Polach, P. ; Anderle, Milan ; Zezula, Pavel ; Papáček, Štěpán
A key feature for bipedal walkers (robots and humans as well) is their stability or disturbance rejection defined as the ability to deal with unexpected disturbances. The paper by Griffin and Grizzle (2017) have significantly contributed to the shift from flat ground to slopes and steps when evaluating the walking efficiency of their robots. Similarly, in this contribution, based on the appropriate model of robot dynamics and control law, we examine the stability of walking-without-falling for different ground perturbations for a threelink compass gait walker. I.e., we perform the sensitivity analysis of the walking stability of underactuated bipedal walker with respect to certain disturbation using the alaska/MultibodyDynamics simulation tool.
|
|
| |
|
|
Advanced Solution to Piston Assembly Dynamics
Dlugoš, Jozef ; Furch,, Jan (oponent) ; Kučera, Pavel (oponent) ; Novotný, Pavel (vedoucí práce)
The ultimate goal of this work is to develop an advanced computational model of piston assembly dynamics. The piston and the liner are interacting through the lubricant film or the surface asperities. This leads to different lubrication regimes and consequently different forces acting on the surfaces of the contact pair. During the solution to hydrodynamics and asperity contact forces, deformation of the piston and the liner has to be taken into account—the process is necessarily iterative in nature. Since the requirements for computational grid of the contact forces and of deformation differ, robust mapping algorithms are proposed. The results of the developed computational tool are experimentally verified. For this purpose, the measurement of the piston secondary motion by laser displacement sensors is conducted. The measurement is done on the experimental sidevalve engine with transparent cylinder head in order to generate compression pressure in the combustion chamber. Measured piston lateral motion is corrupted. Therefore, only measurement of the piston tilt angle is further used. The agreement of the measured and computed results varies during the operation cycle. Good agreement is achieved for compression and expansion strokes. Oppositely, significant differences occur when the side force is small: intake and exhaust strokes. Major contribution of this work is development of computational tool which implements the above mentioned effects that have a major impact on the piston assembly dynamics. Unfortunately, this leads to long computational times, especially when deformation is considered. For this reason, the parallel solution is developed. It is based on the parallelization of the subroutine during the evaluation of the sensibility analysis. This way, the solution time is reduced in order of magnitude.
|
|
|
Řešení příkladů mechaniky těles v ADAMS
Rybár, Šimon ; Švancara, Pavel (oponent) ; Hadaš, Zdeněk (vedoucí práce)
Cieľom tejto práce bolo vytvorenie parametrických modelov technických sústav v programe Adams. Pomocou simulácii boli sústavy skúmané z hľadiska kinematiky a dynamiky. V niekoľkých prípadoch boli výsledky simulácii porovnané s výsledkami získanými analytickou metódou. Práca je rozdelená do troch kapitol. V prvej je formulovaný problém a ciele práce. Druhá definuje multibody systém a bližšie predstavuje použitý program aj s jeho doplnkami. Tretia kapitola obsahuje päť typovo odlišných príkladov, na ktorých sú demonštrované možnosti Adamsu. V závere sú vypísané vlastné postrehy, celkové zhodnotenie a odporučenie pre potreby výuky.
|
host ::
RSS.