Tutorial

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• Publié par: Shyam
• Nombre de lectures: 35
• Langue: English

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1Design Optimization Tutorial
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1 Contents
This tutorial will allow the construction of a complete process flow on a simple case.
The problem is related to the optimization of a welded beam, with references to:
• minimum cost
• minimum deflection at beam end
• satisfying constraints related to admissible stress
Source code is provided to allow compilation on any platform (a C compiler is required)
• 1.1 Problem definition
• 1.2 Starting the system
• 1.3 Design Logic Creation
• 1.4 Handling Input Data
• 1.5 Handling Output Data
• 1.6 Actions Creation
• 1.7 Creating Constraints
• 1.8 Creating Objectives
• 1.9 Design of Experiment
• 1.10 Scheduler (Optimizer)
• 1.11 Run
• 1.12 Assessment
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2Design Optimization Tutorial
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1.1 Problem definition
As a general remark the user should think carefully to what are the free parameters of the problem and what are the
measurable quantities of it.
In this case the beam to be optimized is the one shown in Fig. T1.1.1.
Input Data
• 5 geometrical
parameters
(L, S, H,
T, B)
• Load Value (F)
• Young Module
(Young)
• Material Cost
per Volume
unit (Mc)
• Wel Cost per
Volume unit
(Wc)
Output Data
• Displacement
at the end of
the Beam
(Disp)
• Max Shear
Stress (MaxS)
• Max Normal
Stress (MaxT)
• Material
Volume
(Mvol)
• Weld Volume
(Wvol)
Fig. T1.1.1: a case of study.
It is a rectangular section beam welded at one end and loaded at the other end.
There are 5 parameters defining the geometry, one load value, the young modulus of the material, the weld and
material costs (per unit volume).
3The simulation program will provide the displacement of the beam, the maximum shear and normal stresses, the
volume of the weld and of the beam.
From the data flow point of view there will be 9 input values and 5 output values in total.
The program, a sample of input file, and a sample of output file are available in the directory:
/.../FRONTIER25x/doc/html/tutorial/project
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4Design Optimization Tutorial
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1.2 Starting the system
To start the system, a proper environment should be settled. This can be done as follow:
• for sh, ksh users
export PATH=/.../FRONTIER25x/bin:$PATH
• for csh, tcsh users
setenv PATH=/.../FRONTIER25x/bin:$PATH
• for Microsoft Windows users, click on modeFRONTIER icon.
Now the system can be activated by typing frontier with the following options:
Usage: frontier [−options] [project file]
Options:
−batch name.prj Specify the project file to run in batch.
−verbose The verbose output.
−nConcDes n Number n of Concurrent Design Evaluations [1,128] (Default=1).
−clearDesDir Clear the design directory after evaluation.
−evalDuplDes Evaluate the already present designs.
−delErrorDes Delete the error designs from data base.
−rsmPercentage r RSM r Percentage [1,100] (Default=0).
−priority p Priority of the running processes (0=High,19=Low) (Default=0).
−nobuffer The Display double buffering is disabled.
−unixshell Uses an external Unix−like shell (Windows only).
−classic Uses The Classic Frontier Look and Feel.
−version Prints out the Frontier version number.
−fullversion Prints out the Frontier full version data.
−help This help screen.
The modeFRONTIER welcome screen will pop up and a noname.prj project is loaded.
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5Design Optimization Tutorial
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1.3 Design Logic Creation
The first project tool to be used is the Process Flow (Fig. T1.3.1).
Fig. T1.3.1: the Process Flow window.
This can be activated by clicking on the corresponding tab identified by the icon or selecting
Project|Process Flow from the menu.
The window is divided into three parts:
• the top part ("Graphic Flow", marked in a aqua box): it is the desktop where the logic is created.
• the bottom part ("Logic Log/Summary", marked in a yellow box): click on one of the tabs to toggle between
their respective panels.
6The "Logic Log" panel shows a text commenting the logic created so far and warnings or errors detected by
the just−in−time logic compiler.
The "Summary" panel shows a brief summary of the project, about its components and their relevant
properties; thus it's possible to keep the entire process logic under control with just a glance.
• The left part (a "tool bar" marked in a fuchsia box): it includes all the components needed to create a
working design logic.
Since a successful logic starts from input data and ends with output data, it is better to define these entities first.
These input/output variables can however be completed, modified, created or removed at any time during the logic
creation process.
To place a component on the Graphic Flow desktop, select it by clicking on the left tool bar, then click on the desktop
as many times as the number of objects needed.
Once a component is created, you can select it with a click, access its properties by a double click. With a RMB click
a menu will pop−up menu, where you can select some actions to perform on the component:
• Toggle to toggle the object selected/unselected.
• Remove Node to remove the selected object from the logic flow.
• Remove Links to remove all links from the selected object to any other node previously linked to.
To leave the "component insertion mode" click on the neutral icon on top of the Graphic Flow tool bar.
Let's start creating 9 input variables and 5 output variables selecting the icons from the palette on the left and
placing the items on the Process Flow area (Fig. T1.3.2).
Note: from now on, an "RMB click" will indicate a click with the right mouse button, while an "LMB click" or
simply "click" will indicate a click with the left mouse button.
Fig. T1.3.2: the Process Flow desktop with all variables placed.
7Now set the input and output variables the correct names: to do this, enter the variable properties dialog, by double
clicking on each variable object (Fig. T1.3.3).
Fig. T1.3.3: Input variable properties window.
Variables names and properties can also be modified using the Summary Panel, RMB clicking on a free area of the
Graphic Flow Desktop.
In this example the Young module, S, F, Mc and Wc are kept constant.
The base parameter gives the number of values that each variable can accept.
In this case the beam thickness B can vary from 1 to 15 mm but on finite steps of 1 mm so the variable B will have:
B lower bound = 1
B upper bound = 15
B base = 15
Note: if the Lower Bound and Upper Bound properties are equal, the variable is kept constant and is not
considered by the optimisation algorithms.
After all input variables are renamed and set and all output variables are renamed, you can check the Summary panel
and the result for input and output variable should look like (Fig. T1.3.4).
8Fig. T1.3.4: the Summary Table for input and output variables.
After the variables have been set up, the Process Flow Window should appear like in Fig. T1.3.5.
Fig. T1.3.5: the Process Flow window.
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9Design Optimization Tutorial
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1.4 Handling Input Data
The problem has 9 inputs that can be divided into:
• 5 constants (S, F, Young, Wc, Mc)
• 2 discrete variables (H, B)
• 2 "continuous" (a discretization of 1000 parts is used) variables (T, L).
To provide data to the input variables, we need an input file.
Select the Input File icon from the tool bar and click on the Graphic Flow Desktop to place it. A new input file
object should be now present in the project. To enter the input file properties window, double click on its icon or click
with the RMB to pop−up a menu, then select Properties. The input file object name must be changed to
beam_input.dat, as this is the name of the file required by the application, then all the input variables can be
connected as inputs to the file by clicking on their respective check boxes. By clicking the Apply button all changes
to the logic are applied, the variables are connected and the system should look like Fig. T1.4.1.
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