GEOMETRICALLY NON-LINEAR BEAM ELEMENT FOR DYNAMICS SIMULATION OF MULTIBODY SYSTEMS

1996 ◽  
Vol 39 (5) ◽  
pp. 763-786 ◽  
Author(s):  
I. SHARF
Keyword(s):  
Multibody Systems ◽  
Beam Element ◽  
Dynamics Simulation ◽  
Non Linear

Parallel Efficiency of Lagrange Multipliers Based Divide and Conquer Algorithm for Dynamics of Multibody Systems

2011 ◽  
Author(s):  
Paweł Malczyk ◽  
Janusz Fra¸czek
Keyword(s):  
Parallel Computing ◽  
Lagrange Multipliers ◽  
Multibody Systems ◽  
Open Loop ◽  
Divide And Conquer ◽  
Dynamics Simulation ◽  
Parallel Computer ◽  
Optimal Order ◽  
Parallel Efficiency ◽  
Divide And Conquer Algorithm

Efficient dynamics simulations of complex multibody systems are essential in many areas of computer aided engineering and design. As parallel computing resources has become more available, researchers began to reformulate existing algorithms or to create new parallel formulations. Recent works on dynamics simulation of multibody systems include sequential recursive algorithms as well as low order, exact or iterative parallel algorithms. The first part of the paper presents an optimal order parallel algorithm for dynamics simulation of open loop chain multibody systems. The proposed method adopts a Featherstone’s divide and conquer scheme by using Lagrange multipliers approach for constraint imposition and dependent set of coordinates for the system state description. In the second part of the paper we investigate parallel efficiency measures of the proposed formulation. The performance comparisons are made on the basis of theoretical floating-point operations count. The main part of the paper is concetrated on experimental investigation performed on parallel computer using OpenMP threads. Numerical experiments confirm good overall efficiency of the formulation in case of modest parallel computing resources available and demonstrate certain computational advantages over sequential versions.

Linearization and Model Reduction of Contact Dynamics Simulation

2011 ◽  
Author(s):  
Jianxun Liang ◽  
Ou Ma ◽  
Caishan Liu
Keyword(s):  
Model Reduction ◽  
Multibody Systems ◽  
Reduction Method ◽  
Contact Dynamics ◽  
Dynamics Simulation ◽  
Dynamics Model ◽  
Time Step ◽  
Reduction Techniques ◽  
Proposed Model ◽  
Simulation Time

Finite element methods are widely used for simulations of contact dynamics of flexible multibody systems. Such a simulation is computationally very inefficient because the system’s dimension is usually very large and the simulation time step has to be very small in order to ensure numerical stability. A potential solution to the problem is to apply a model reduction method in the simulation. Although many model reduction techniques have been developed, most of them cannot be readily applied due to the high nonlinearity of the involved contact dynamics model. This paper presents a solution to the problem. The approach is based on a modified Lyapunov balanced truncation method. A numerical example is presented to demonstrate that, by applying the proposed model reduction method, the simulation process can be significantly speeded up while the resulting error caused by the model reduction is still within an acceptable level.

Non-Linear FE Approach for Flexible Multibody Simulation of Mechanism Dynamics

1998 ◽  
Author(s):  
Ole Ivar Sivertsen
Keyword(s):  
Finite Element ◽  
Multibody Systems ◽  
Nonlinear Finite Element ◽  
Component Mode Synthesis ◽  
Simulation Approach ◽  
Multibody Simulation ◽  
Non Linear ◽  
Flexible Multibody ◽  
External Forces

Abstract The simulation approach presented in this paper is based on a nonlinear Finite Element (FE) formulation for modelling of multibody systems (MBS). This formulation is developed to include a comprehensive library of MBS elements as links, joints, springs, dampers and external forces. The links are modelled as FE substructures and reduced to super elements by component mode synthesis (CMS). Super nodes are used for modelling of the mechanism elements referred to above.

scholarly journals Optimisation of injection-related parameters using the non-linear programming by quadratic Lagrangian algorithm for a marine medium-speed diesel engine

2017 ◽  
Vol 19 (5) ◽  
pp. 570-583 ◽  
Author(s):  
Nao Hu ◽  
Jianguo Yang ◽  
Peilin Zhou
Keyword(s):  
Linear Programming ◽  
Combustion Process ◽  
Dynamics Simulation ◽  
Spray Angle ◽  
Design Parameters ◽  
Swirl Ratio ◽  
Injection Angle ◽  
Non Linear Programming ◽  
Start Of Injection ◽  
Non Linear

The match of an injector with the combustion chamber was studied through computational fluid dynamics simulation under four different engine loads. Four design parameters including the start of injection, spray angle, injector protrusion length and swirl ratio were examined. The Latin hypercube together with a non-linear programming by quadratic Lagrangian algorithm were used in the optimisation. Comparisons were made in the engine loads in terms of the optimisation history, objectives, sub-objectives and design parameters. The commonalities of the design parameters of the optimums were summarised. Additionally, a detailed combustion process comparison was conducted on the same engine loads (100% and 25% engine loads) between the optimum and baseline designs, respectively. Finally, the effects of the design parameters on the objective were investigated by the response surface methodology. The results indicate that the non-linear programming by quadratic Lagrangian method is an effective algorithm to spot the optimums with the best trade-off between nitrogen oxides and soot emissions. The optimisation process presents better qualities at 100% and 75% engine loads than in the case of 50% and 25% engine loads. The design parameters of the optimum under each engine load have something in common, namely, that they all prefer late injection, low swirl, large injection angle and slightly smaller nozzle protrusion length. Besides, start of injection and swirl ratio have larger influence on the objective as opposed to the nozzle protrusion length and spray angle. The large start of injection together with the small swirl ratio can reduce the objective significantly and vice versa. A large nozzle protrusion length with a small spray angle contributes to the reduction of the objective and so does the combination of a small nozzle protrusion length with a large spray angle.

Computing Sensitivity Analysis of Vehicle Dynamics Based on Multibody Models

2013 ◽  
Author(s):  
Yitao Zhu ◽  
Daniel Dopico ◽  
Corina Sandu ◽  
Adrian Sandu
Keyword(s):  
Sensitivity Analysis ◽  
Vehicle Dynamics ◽  
Multibody Systems ◽  
Dynamics Simulation ◽  
Adjoint Sensitivity ◽  
Analysis And Design ◽  
Systems Analysis And Design ◽  
Dynamics Of Multibody Systems ◽  
Direct Sensitivity ◽  
Vehicle Suspension System

Vehicle dynamics simulation based on multibody dynamics techniques has become a powerful tool for vehicle systems analysis and design. As this approach evolves, more and more details are required to increase the accuracy of the simulations, to improve their efficiency, or to provide more information that will allow various types of analyses. One very important direction is the optimization of multibody systems. Sensitivity analysis of the dynamics of multibody systems is essential for design optimization. Dynamic sensitivities, when needed, are often calculated by means of finite differences but, depending of the number of parameters involved, this procedure can be very demanding in terms of time and the accuracy obtained can be very poor in many cases if real perturbations are used. In this paper, several ways to perform the sensitivity analysis of multibody systems are explored including the direct sensitivity approaches and the adjoint sensitivity ones. Finally, the techniques proposed are applied to the dynamical optimization of a five bar mechanism and a vehicle suspension system.

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