3. The Virtual System. Overview of modeling technichs Flashcards
What are the basic types of model to use for the virtual assets?–with other words to represent the digital twins
Static Relation: is related to the current configuration at that moment, like stresses.
Dynamic relation: Here we are interest in how the quantities or situation evaluates in time. That has an impact on the system.
What are the forward and inverse analysis, what is inversion
in Forward analysis we try to see the progress of the inputs and the outputs (response of the system)
Inverse analysis. here we try to analys the inputs that cause the outputs
Inversion, is used in static cases, its a math application, whereas we must perform invers analysis
How to transfer mathematics (model) to computer (digital) solutions?
- Equations based on empirical knouwledge (easy to use).
- Differential Equations: Ordinary, these are only with derivatives- the systems are LINEAR. they depends on the evoulution of time. See the equations dots
- Partial differential equations. Here we have more variables, by names, fisical changes and also changes on time
What are the wite box models
We want to evaluate from white box to black box
White box. are models that are based on physical situations, models that are based on equations. Are physics based!
Black box models. No physics but it can emmulate the process
What is the goal of ussing different models
The goal is to have multiple models, one for each dicipline. We see this on the application layer of the digital twin models
Multibody simulation, what simulation to use?
Here we need inputs (motions) and motion (outputs);
How to split solver from model setup invorenment?
Having a undifined objects and we want to know how its behave when we apply inputs and we can apply PDE
We should use FEM, so we represent the object with independent pieces, for which we can have a analitical solutions
Describe equations of continuum mechanics, what is the basic idea
That we describe the deformation of all the points (mesh) in the body
What are the constutive equations–what are the isotropic materials
Are equations that describe the material behaviour (stresses and strains)–you have movement (deflections) in all different directions
How to solve the PDE which describe the movement of the materials
We use FEM to solve the equations
WHat is the main goal
to have a CAD and afterwards descritized the cad (mesh)–>we want the shape functions
What are the resulting equations after applying the mesh
Stiffness matrix en mass matrix
Which type of equations we have and how to analyze them
the eigen freq meassure the response of the real time in order to see how it looks like
What are the limitations of a (regular) FEA
That we can’t apply them to non linear systems, by means, systems with motions
Example
Explain 1D lumped parameter simulation
Ideal for realtime simulations
Why to still use matlab and simulink?
Bond-graph—Limitations?
Arent vector form only singel effort (1 quantity) - NO interactions like in a FEA
Example mass-spring bond
We want the equations of motions - the sum of all the forces has to be zero
test
Example bond elek
Always dont forget the preservartion of energy
Bond junctions
When to use model order reduction
When we have a lot of DOF, a lot of information, very big models. So we try to find smaller versions of the model with limited DOF and by doing approximations we can go back to the original model…“Try to get rid off stuffs”
What are the parametric models and why do we use them, which kind of parametrization can be used in structures
the models still works if we change the parameters, like the materials parameters
What is Singular Value Decomposition and when to use it
We only extract the important parts whenever we have parametric variations
More of SVD
