2.) Hardware and Virtual models
Hardware models
- Clay model for styling
- Wood model for first functional tests
- Physical Mock-Ups for functional optimization (seat box, ergonomics, ...)
- Rapid prototyping for evaluation
- Test bench configurations
Virtual models
- Functional structure diagrams
- Geometry models (2D-/ 3D-CAD, DMU)
- Simulation Models (FEM, CFD, MBS, ...)
- Functional simulation models (test of control systems)
- Production simulation (CNC, ...)
- Data structure models (PDM) - Cost calculation models
1.) Product modeling
• A model is a simplified reproduction of an existing or an imaginary system in a different conceptual or representational system (within specified boundaries to enable a specified investigation).
• Models are used to find solutions for problems, which would be not possible or to complex with the original system.
• Models reduce the real conditions to focus the essential aspects of the particular investigation.
• Models simplify and reduce complex systems.
• Models are the basis for the reproduction of product characteristics in virtual development and simulation software tools (CAD, FEM, DMU, PDM, etc.).
Trends:
• Increasing product variety and product complexity
• Integration of different technical disciplines into the development process
• Manifold data formats and structures with interdisciplinary relationships - Disposition of project data on several (global) locations
3.) Two different principles in building a computation model:
- Physical models are based on physical laws or axioms, which allow a mathematical description of the considered process(es). The resulting equations usually need to be solved by numerical algorithms.
Advantages: physical meaning of the system parameters, physical insight into the nature of the considered process.
- Phenomenological (or empirical) models are based on mapped approximations of measured or observed phenomena without direct application of mathematical description of physical laws.
Advantage: High computational efficiency.
4.) Comparison: Simulation <—> Measurement, Advantages of
Simulation (calculation):
Advanced pre-investigations
Studies of alternative variants
Reproducibility of results
Derivation of difficultly measurable quantities
Measurement (testing)
Results contain all the influences
Discovery of remaining weak points
Subjective fine tuning
Trouble shooting
Production release competence
5.) Model building
- The material vehicle system (vehicle, -component, media) can be understood as connected group of different continuous bodies („continua“).
- The characteristics of these continua are density, stiffness and viscosity.
- Each of these continua is an infinite-dimensional quantity of material points, which must be discretized into a finite- dimensional structure for computer friendly processing.
- This discretisation process is called modelling or model building.
- The way, how to perform the discretization characterizes the respective CAE method.
MBS: Separation of the locally distributed parameters into discrete parameters: mass, inertia, stiffness, damping etc. „physical discretisation“
FEM: Separation of the continuum into finite, simple areas or volumes: Finite elements, connected at defined nodes „mathematical discretisation “
Last changed2 years ago
