Multibody Dynamics Workshop 2016
11-15 April 2016, Parma

Calendar

Program

Monday 11-4-2016

From computer-aided geometrical model to multibody model

The widespread use of computer-aided design software has tremendously changed the approach to the design of products. This transformation has also involved the methodology for building multibody dynamic models. The user-friendliness of the design environment and the automation of procedures and tools allow a fast building of complex three-dimensional models reducing the time and cost in many design phases. On the other hand, there is the risk of losing control on every aspect of the model and including possible errors which produce wrong analyses and results. The purpose of the lecture is to give a comprehensive guideline in order to produce a conscious building of a dynamic model starting from a geometric modelled assembly. Several aspects about the translation of assembly constraints, managing redundancies, undertaking reasonable simplifications, avoiding common pitfalls, dealing with contacts and real joints will be faced. Moreover, several practical examples will be discussed.

Multi-body models for real-time applications – the Dallara Experience

1) Introduction to multi-physics softwares ( Modelica, Dymola )
2) Real-time and Off-line Dallara models ( overview )
3) An application : design of the “Super Formula” Racecar
4) Future developments:
- electric powertrain modeling
- vehicle models with suspension compliances suitable for real-time simulations
5) Job Opportunities at Dallara
- Competencies in Vehicle Dynamics ( Universities )
- Formula SAE experience
- Experience with Modelica / Dymola (using Academic licenses)

New Paradigms in MBS: RecurDyn

RecurDyn is a Multibody Dynamics (MBD) simulation software with extended multiphysics capabilities. It combines the power of an optimized recursive solver with a superior contact technology, providing best-in-class performances. Thanks to the proprietary FullFlex technology, RecurDyn is the only multibody software that bridges the gap between Finite Element and Multi Body Dynamics. It includes interfaces to Computer Fluid Dynamics (Moving Particle Simulation) or Particle Dynamics (Discrete Element Method), which allow the simulation of mechanisms with unconventional boundary conditions. Moreover, co-simulation is possible in conjunction with matlab simulink to assess realistic mechatronic systems.

MBS for Industry by EnginSoft

In the past 10 years, EnginSoft has been involved in a large number of projects requiring MultiBody Simulation. In some sectors, such as home appliances, electrical switches, and two wheeled vehicles, EnginSoft has worked together with its Customers becoming a reference resource for Design and Development. In other sectors, such as Oil&Gas, Automatic Machines and general mechanisms, EnginSoft's means and capabilities have been exploited for troubleshooting and fast solution of practical issues. In this session some selected applications (many cannot be disclosed for confidential reasons) are shown to provide an overview of what multibody simulation can do for industries.

Recurdyn premium contact technology

A weak point of many multibody simulators is represented by contacts. Generally speaking, contacts introduce large discontinuities in the mathematical problem, slowing down the integration. Moreover, if the contact force is not correct (in module, direction and application point) the resulting dynamics of contacting bodies is not correct as well. RecurDyn includes a very extended library of contacts (more than 30 types) organized in three categories: General, Primitive 3D and Primitive 2D. The "General" group include those contacts that calculate the repulsive forces between surfaces with generic shape. Force calculation starts from a surface mesh, which is elaborated through a proprietary technology to obtain a smooth contact response, while preserving calculation efficiency. The "Primitive" groups include those contacts that are defined between solids with regular shape that can be described analytically. Primitive contacts allow very fast calculation and should be preferred whenever it is possible to use them. Thanks to the wide number of primitives included in the library, RecurDyn Primitive contacts suit a huge number of situations. For all contact types, RecurDyn technology features multiple options, which allows to finely control the generation of the contact force.

RecurDyn Toolkits: MTT as an example

RecurDyn includes a library of toolkits, which have been developed to efficiently create and post-process models of systems & sub-systems that, otherwise, would require a long modeling and processing time. RecurDyn toolkits are suitable to create flexible springs, belts, engines, chains, timing systems, gears, tracks and media transportation systems. In this tutorial, we present the Media Transportation Toolkit, which automates the creation of sophisticated models of flexible media being transported by a mechanical systems. RecurDyn/MTT includes templates for rollers and guides, as well as, options for material response and dedicated contacts. RecurDyn is the only commercial code that has the capability to analyze flexible sheets that undergo large deformations in presence of contacts with guides and rollers. Any kind of distributed force can be added to the model as well, including vacuum forces, electrostatic attraction, and aerodynamic forces. The RecurDyn/MTT is very effective to investigate effects such as sheet velocity, change in material properties, gaps, misalignments and so on in printers, copiers, fax, or other sheet and film feeding products.

From MBS to FEMBS: one step closer to reality

RecurDyn development is really focused on extending the capabilities in simulating flexible systems: the synergy of FEM and MBD simulations is the future for more realistic analysis results. Nowadays, the most common approach to get fexible bodies running in multibody models is based on the modal reduction (called RFlex in RecurDyn). RFlex is rather efficient for a wide family of problems and is very suitable for enhanced vibration analysis in time domain. RecurDyn RFlex uses modal data from the most common FEA codes, but the platform also includes both a mesher and a FE solver to internally calculate the needed modal data. RFlex approach has as well some known limits: it is not applicable when bodies undergo large deformation and is not indicated when flexible bodies get in contact with other bodies. For these reasons, RecurDyn has been equipped with an innovative technology called FFlex which is an optimized implementation of the Finite Element approach. This technology breaks all the limits of the RFlex approach, while preserving a computational efficiency that is not reachable by pure FE codes.

Tuesday 12-4-2016

Ortogonalization of kinematic constraints in multibody dynamics simulations

Review and advantages of methods for the elimination of kinematic constraints through orthogonalization.
The methods based on QR and Singular Value decompositions will be discussed in depth as well as their computer programming.

Natural Orthogonal Complement Method in multibody dynamic systems

Review and advantages of the Natural Orthogonal Complement Method (N.O.C.) in multibody dynamic systems.
The dynamic analysis of simple and complex mechanisms is simplified by the introduction of the N.O.C. method that is applied to derive the dynamic equations in form of E-L eqs. starting from N-E eqs.
Applications in parallel kinematic mechanisms are shown.

Methods and tools for virtual prototyping: the importance of Multibody and Multidiscipline analysis from Early Design to Validation and Verification

The importance of the Virtual Prototyping and Numerical Simulation in the Product Life Cycle: from Design to Engineering and Validation
The evolution of the Adams simulation tool from rigid body analysis to multidiscipline simulation (including structural, control, CAD interoperability, FMI, etc)
How the simulation is used in the main industries: aerospace, automotive, machinery, robotic, medical, transportation, spatial
Industrial and Academic Case Studies
Modelization and Analysis
Parameterization and Optimization
Importance of Post processing and results management

ADAMS hands-on

[Hands-on session with ADAMS and MSC software tools]

Wednesday 13-4-2016

State estimation: from system theory to multibody system dynamics

In the last years, the interest of the multibody community towards state estimation has been increasing significantly.
The lecture aims at discussing the main issues to be tackled for the development of effective and stable state estimators, by taking advantage of some fundamental concepts of both the system theory and of multibody system dynamics.
Attention will be paid in particular to the Kalman filter, both in the linear and non-linear formulations. Some applications and new concepts of state estimation in multibody systems, that have been recently proposed, will be finally discussed as case studies.

Contact models in multibody systems and application to raiway vehicles

Contact modelling is one of the critical issue in multibody systems, both in terms of accuracy and numerical efficiency.
In this talk, standard and advanced contact models employed in multibody systems simulation will be introduced, highlighting strengths and weaknesses of the different approach.
As study case, particular attention will be paid to the wheel-rail contact in railway systems.

Introduction to Flexible Multibody Dynamics

This module presents an introduction to the handling of flexible structural components in multibody dynamics.
Particular focus is placed on lumped deformable components and beams (using the Geometrically Exact Beam Formulation). A comparison between alternative approaches will be discussed and benchmarks will be proposed.
In the following hands-on session, some benchmarks will be developed by the attendees under the guidance of the instructor, using the free general-purpose MBDyn software.

MBDyn hands-on

A hands-on session will be proposed using the free, general-purpose solver MBDyn http://www.mbdyn.org/.
Benchmarks will be proposed and developed by the attendees under the guidance of the instructor.

In order to use MBDyn, attendees are encouraged to have the software set-up in advance on their laptops. Linux (and Mac) users can follow instructions on the website. Windows users who already have a MSYS/MinGW or a CygWin environment set-up can follow instructions for Linux; otherwise, a pre-compiled Windows executable will be made available at the workshop.

Thursday 14-4-2016

Udwadia-Kalaba approach to the constrained motion of multibody system

- Cartesian, generalized, lagrangian coordinates. Constraints.
- Configuration space: geometric rappresentation of constraints, infinitesimi, possible, elementar, virtual displacements, C-trajectory
- Lagrange equations of motion
- UK fundamental equation: constrained motion, standard constrain eq., Gauss principle, Moore Penrose inverse generalized of a matrix
- Multibody system dynamics modeling based on UK equation
- A numerical example

Symbolic Approach to Multibody/Multiphysics Modeling

This lecture will discuss recent advancements in the field of symbolic approaches to multibody modeling. Details will be presented also about multibody/multiphysics modeling, with examples and benchmarks.

Modelling Rigid-Flexible Multibody Systems using Absolute Coordinates

A general review of the modern formulations for the kinematical and dynamical analysis of rigid and flexible multibody systems is shown.
Particular attention is given to the Natural Absolute Coordinate Formulation (NACF) for the description of rigid multibody systems and to the Absolute Nodal Coordinate Formulation (ANCF) for the description of flexible multibody systems.
The advantages and the drawbacks of these two formulation methods are discussed in details.

Non-smooth dynamics in multibody contact problems

An overview of numerical methods for the simulation of non-smooth multibody systems will be presented.
A background in variational inequalities, differential-variational inequalities, measure differential inclusions and differential-algebraic problems will be given, and appropriate time-stepping integration schemes will be discussed.
A formulation for the case of frictional unilateral contact problems in large scale problems will be introduced, and numerical issues will be discussed.
The session will be complemented with a primer on computational geometry, namely on broad-phase and narrow-phase collision detection algorithms, in order to provide efficient methods for generating the contact manifolds during the simulation of contacts between a massive amount of complex shapes.
The open-source Chrono::Engine software, used in a following hands-on session, implements the above concepts.

HPC in Computational Dynamics

This talk outlines some of the main research thrusts at the Simulation-Based Engineering Lab at the University of Wisonsin - Madison, highlighting how parallel computing is used to gauge the dynamics of granular materials, to simulate ground vehicles and their interaction with deformable terrain, and to describe fluid-solid dynamic coupling. We touch on formulations and algorithms suitable for different platforms (GPU, multi-core, distributed), on related research directions (e.g., solution of sparse linear systems on the GPU), and parallel computing benchmarching.

Chrono overview

This talk is a high-level overview of Project Chrono, an open-source multi-physics dynamics engine. Its forte is the handling of complex and large dynamic systems containing millions of rigid bodies that interact through frictional contact. Chrono has been recently augmented to support the modeling of fluid-solid interaction (FSI) problems, linear and nonlinear finite element analysis (FEA), and modeling of ground vehicles. We provide a brief overview of Chrono's design and architecture, its capabilities, and directions of current and future development and show some of its applications in a variety of engineering applications.

Chrono hands-on

In this session we go through a couple of simple exercises to introduce the interested participants to the architecture and API of Chrono. We focus on modeling and simulation of simple multibody systems using a slider-crank model to demonstrate the modeling and simulation of systems consisting of rigid bodies, joints, force elements and inclusion of frictional contact interaction.
The Chrono solver is available at:
http://www.projectchrono.org/.

In order to use Chrono, attendees are encouraged to have the software set-up in advance on their laptops. This requires other tools to be installed too (a compiler like VisualStudio, a GIT client like SourceTree, the CMake build tool, the Irrlight library). Follow instructions on the http://www.projectchrono.org/ website for more details.

Friday 15-4-2016

Multibody System Dynamics for powertrains: the Ferrari experience

Developing efficient power trains for high performance cars is a challenging task that involves advanced computational tools. During these years, Ferrari Automobili leveraged on the capabilities of multibody simulation software to design and optimize various sub-systems of their power trains. Some cases will be discussed, about:
- valve trains and timing chains
- drive-lines, clutches, flywheels
- elasto-hydro-dynamics of bearings
- rotor dynamics of crankshafts
etc.

Application of multibody dynamics to human body motion

The human body can be considered as a multibody system in which bones are the rigid bodies connected at the joints, and actuated by muscles governed by the central nervous system. Therefore, multibody dynamics techniques can be applied to the study of the kinematics and dynamics of human body motion. In the lecture, the conventional methods followed to analyze real human motion will be described, along with the large number of difficulties that arise in the process, and which make this application much more challenging than the traditional ones focusing on machines or vehicles. Motion prediction, the next step to motion analysis and a topic of current intensive research, will also be introduced.

Multibody dynamics in winter sports

[detailed program available later]

Vehicle dynamics

[detailed program available later]