COMPUTER AIDED DESIGN OF SHEET METAL DIE ASSEMBLY UTILISING
PRO | ENGINEER AND MECHANICA
Vamshikrishna Reddy Chada
B.Tech. Jawaharlal Nehru Technological University, India, 2007
PROJECT
Submitted in partial satisfaction of
The requirements for the degree of
MASTER OF SCIENCE
in
MECHANICAL ENGINEERING
at
CALIFORNIA STATE UNIVERSITY, SACRAMENTO
FALL
2010
COMPUTER AIDED DESIGN OF SHEET METAL DIE ASSEMBLY UTILISING
PRO | ENGINEER AND MECHANICA
A Project
by
Vamshikrishna Reddy Chada
Approved by:
________________________________, Committee Chair
Dr.Yong S.Suh
_________________________
Date
ii
Student: Vamshikrishna Reddy Chada
I certify that these students have met the requirements for format contained in the
University format manual, and that this project is suitable for shelving in the Library and
credit is to be awarded for the project.
________________________, Graduate Coordinator
Dr.Kenneth Sprott
Department of Mechanical Engineering
iii
_____________________
Date
Abstract
of
COMPUTER AIDED DESIGN OF SHEET METAL DIE ASSEMBLY UTILISING
PRO | ENGINEER AND MECHANICA
by
Vamshikrishna Reddy Chada
In recent years the development of more and more products has become a remarkable
trend in the automotive industry.The consumer demand for great variety and increasing
environmental concenrs are forcing manufacturers to improve product development
efficency encouraging the new desings in sheet metal die casting.The Pro Engineering
and Pro Engineering Mechancia is a widely applied tools for designing models and for
solving structural problems respectively.The punch,die and blankholder are three main
parts in this sheet metal die casting and these can be representedy by finite element
models,the die structure deflections and stress induced by loading condition can be
predicted and can be designed according to requirements.The role of the blank holder in
the generation of the restraining forces acting on the metal sheet is considered on top
most point.The known fact is the choice of restraining force distribution is a key point in
designing the sheet metal die.The factors that affect the actual restraining force
distribution are briefly analyzed,identifying control factors.This capability allows
achieving some actual advantages, considering that the technological development will
iv
supplies the engineers with hardware and software instruments able to analyze in short
time large problems.The Finite element analyis allows to foresee possible inconveniences
which could occur during the consturction by using only virtual models,before physical
model being made.
________________________________, Committee Chair
Dr.Yong S.Suh
______________________
Date
v
ACKNOWLEDGMENTS
While working on this project, some people helped me to reach where I am today and I
would like to thank all for their support and patience.
Firstly, I would like to thank Professor Dr. Yong S.Suh for giving me an opportunity to
do this project. His continuous support was the main thing that helped me to develop
immense interest on the project that led to designing of punch and die assembly with
emerging technologies.
Dr.Yong S.Suh helped me by providing many sources of
information that needed from beginning of the project till the end. He was always there
to meet, talk and answer the questions that came across during the project.
Special thanks to my advisor Dr Kenneth Sprott for helping me to complete the writing of
this dissertation, without his encouragement and constant guidance I could not have
finished this report.
Finally, I would also like to thank all my family, friends and Mechanical engineering
department who helped me to complete this project work successfully. Without any of
the above-mentioned people the project would not have come out the way it did. Thank
you all.
vi
TABLE OF CONTENTS
Page
Acknowledgments...................................................................................................... VI
List of Figures ............................................................................................................. XI
Chapter
1. INTRODUCTION AND BACKGROUND ..............................................................1
1.1) Introduction ............................................................................................................1
1.2) Foundry Casting .................................................................................................... 2
1.3) Specifications......................................................................................................... 3
1.3.1) Upper Die ............................................................................................... 3
1.3.2) Blank Holder........................................................................................... 4
1.3.3) Lower Die Punch .................................................................................... 4
1.4) Diagrammatic View of Model ............................................................................... 5
1.5) Working Principle...................................................................................................6
1.6) Problem Description .............................................................................................. 7
1.7) Tools used for Modeling and FEA ........................................................................ 8
1.7.1) Pro/ENGINEER .................................................................................... 8
1.7.2) MECHANICA ....................................................................................... 8
vii
Chapter
2. DESIGN USING Pro/ENGINEER ........................................................................ 10
2.1) Introduction ......................................................................................................... 10
2.2) General Terms ..................................................................................................... 11
2.3) Geometric Terms ................................................................................................. 12
2.4) Pro/ENGINEER Versions ................................................................................... 13
2.5) Design of Sheet Metal Die Parts.......................................................................... 14
2.5.1) Design of Upper Die ............................................................................ 14
2.5.2) Design of Blank Holder ....................................................................... 15
2.5.3) Design of Lower Die Punch ................................................................. 16
2.5.4) Design of Pattern Surface Part.............................................................. 17
2.5.5) Design of Upper Die Surface Part ........................................................ 18
2.6) Design of Sheet Metal Die Assembly ................................................................. 19
2.6.1) Assembling Upper Die and Upper Die Surface.................................... 19
2.6.2) Assembling Lower Die and Pattern Surface......................................... 20
2.6.3) Die Assembly ....................................................................................... 21
2.7) Sheet Metal Die Exploded View ......................................................................... 22
Chapter
3. FEA ANALYSIS USING MECHANICA ............................................................. 23
3.1) Introduction ......................................................................................................... 23
viii
3.2) Problems Solved Using MECHANICA .............................................................. 23
3.3) Steps in Preparing an FEA Model ....................................................................... 24
3.4) Setting Up the Model in MECHANICA ............................................................. 26
3.4.1) Running MECHANICA ....................................................................... 26
3.4.2) Material Specification........................................................................... 27
3.4.3) Applying the Pressure Load ................................................................. 29
3.4.4) Defining Displacement Constraints ..................................................... 30
3.4.5) Defining Planar Constraint................................................................... 31
3.4.6) Running Basic Static Analysis ............................................................. 32
3.4.7) Running Auto Gem ............................................................................... 34
3.4.8) MECHANICA Convergency.................................................................35
3.4.8) Setting up Optimum Design Study ....................................................... 46
Chapter
4. RESULTS ................................................................................................................48
4.1) Results from Basic Static Analysis .......................................................................48
4.2) Results from Optimum Design Study Analysis ................................................... 48
4.3) Basic Static Vs Optimization-Deflections ............................................................49
4.4) Basic Static Vs Optimization-Stresses ................................................................ 50
4.5) Basic Static Vs Optimization-Principal Strain .................................................... 52
4.6) Dimensional Changes in Die Assembly ...............................................................54
ix
4.7) Graphical Results ................................................................................................. 55
4.8) Optimized Auto Gem............................................................................................57
CHAPTER
4. FEATURE WORK .................................................................................................58
References ...................................................................................................................59
x
LIST OF FIGURES
1. Figure 1.4-1
Sheet Metal Die Assembly........................................
2. Figure 2.5-1
Upper Die.............................................................
14
3. Figure 2.5-2
Blank Holder........................................................
15
4. Figure 2.5-3
Lower Die Punch..................................................
16
5. Figure 2.5-4
Pattern Surface.....................................................
17
6. Figure 2.5-5
Upper Die Surface Part........................................
18
7. Figure 2.6-1
Upper Die Assembly.............................................
19
8. Figure 2.6-2
Lower Die Assembly............................................
20
9. Figure 2.6-3
Die Assembly........................................................
21
10. Figure 2.7-1
Exploded View.....................................................
22
11. Figure 3.3-1
Steps for FEA......................................................
25
12. Figure 3.4-1
Model Setup.........................................................
26
13. Figure 3.4-2
Material Definition.................................................
27
14. Figure 3.4-3
Assigning Material.................................................
28
15. Figure 3.4-4
Assigning Load.....................................................
29
16. Figure 3.4-5
Assigning Displacement Constraint........................
30
17. Figure 3.4-6
Assigning Planar Constraint...................................
31
18. Figure 3.4-7
Setting up Basic Analysis.......................................
32
xi
5
19. Figure 3.4-8
Running Basic Analysis..........................................
33
20. Figure 3.4-9
Running Auto Gem.................................................
34
21. Figure 3.4-10 Setting up Convergence..........................................
35
22. Figure 3.4-11 Running Multi-pass Adaptive Test...........................
36
23. Figure 3.4-12 Setting Up Optimum Design Study..........................
46
24. Figure 3.4-13 Running Optimum Design Study............................
47
25. Figure 4.3-1
Deflections in Fringe Display Type..........................
49
26. Figure 4.4-1
Stresses in Fringe Display Type..............................
50
27. Figure 4.4-2
Maximum Stress Locations.....................................
51
28. Figure 4.5-1
Principal Strain in Fringe Display Type...................
52
29. Figure 4.5-2
Maximum Principal Strain Locations.......................
53
30. Figure 4.6-1
Dimensional Changes in Die Assembly...................
54
31. Figure 4.7-1
Graphical Area Considered.....................................
55
32. Figure 4.7-2
Deflections in Graphical Display Type..................... 56
33. Figure 4.8-1
Auto-Gem after Optimization...................................
xii
57
1
Chapter 1
INTRODUCTION AND BACKGROUND
1.1) Introduction:
In recent years the development of more and more cars with different external appearance
has become a remarkable trend in the automotive industry. As another trend the
increasing use of high and ultrahigh strength steel grades for bodies should be mentioned.
Both trends generate higher costs for individual tools that are traditionally made as stiff
as possible. Sheet Metal Dies, one of the tools used in making sheet metal parts for
automobile industry account 35% of total cost of a vehicle program. The construction
cost of these dies is used as benchmark by the automotive companies to evaluate the cost
of any new vehicle program and also to determine where they stand compared to their
competitions.
These sheet metal dies are designed accordingly for a particular company based on the
internal process, safety guidelines and press allocations. As these sheet metal dies are
operated regularly and subjected to various load conditions in their lifecycle and hence
the die should provide sufficient safety factor to prevent any structural failure of dies and
also should compensate the elastic deformations or deflections. The die breakage during
production can cause a complete halt of production which stops the production cycle in
an industry. Due to this extreme importance of these dies to be safe during the entire
production cycle the die design standards are made very traditional and dies thus made of
heavy weight. Due to this heavy structure of the dies, the cost of raw material,
2
construction costs, operating costs are huge. But, now the availability of finite analysis
can be performed on these dies for various line die operations and opportunities to
explore savings in weight can be explored to reduce the structural and operating costs.
The various safety measures can be analyzed by thorough finite element analysis and also
root cause of the breakage problems can be fixed in a more efficient manner.
The two key requirements of tool design are meeting functional performances and
achieving greater manufacturing reliability. There are number of important areas of the
die that can be standardized and helps to reduce the manufacturing cost and production
time. This applies more intended to pattern making activities that are time consuming,
expensive and more human errors.
1.2) FOUNDRY CASTING:
The old fashioned and manual approach to foundry pattern making has number of
drawbacks like

Dimensional accuracy cannot be assured

Manufacturing times are too long

Excess material on critical areas of the casting can result in poor quality and a
weaker casting

Poor quality pattern joints are a potential source of casting weakness and thus
compromise safety.
3
The above errors can be overcome by using standard pieces and NC machining of
working surfaces, but designing the automated sheet metal casting dies are more helpful
compared to this old fashioned pattern making.
1.3) SPECIFICATIONS:
The sheet metal die assembly mainly consists of three parts. They are
1.3.1) UPPER DIE: Upper die is the upper portion of a die set that corresponds with
the lower die via blank holder and move down onto the work piece. Upper die is of
rectangular shape with hallowing centered area. All the four side of the upper die is
composed of rectangular ribs which make the force applied to be distributed evenly.
The upper area of the die is divided with uniform rectangular ribs which are useful to
place press slider firmly. The bottom part of the die consists of ten equally
dimensioned pins which lie on blank holder pins. The dimensions of the upper die
and material specifications are as follows.

Length = 1650 mm

Width = 1170 mm

Height = 485 mm

Upper ribs = 230 * 200 mm

Side ribs = 460 * 200 mm

Material Used = High strength Steel

Density of Steel = 7.82708e-09 ton/mm^3
4

Poisson’s ratio = 0.27

Young’s Modula’s = 19.98 Mpa
1.3.2) BLANK HOLDER: The Blank holder is used to prevent the edge of a sheet
metal blank from wrinkling during deep drawing operations. Blank holder is
of rectangular in shape with rectangular ribs on bottom part. It has cushioned
pins on the bottom which lie on punch die. The dimensions and material
specification is as follows.

Length = 1650 mm

Width = 1215 mm

Height = 220 mm

Bottom ribs = 215 * 155 mm

Material Used = High strength Steel

Density of Steel = 7.82708e-09 ton/mm^3

Poisson’s ratio = 0.27

Young’s Modula’s = 19.98 Mpa.
1.3.3) LOWER DIE PUNCH: Punch die is bottom part of the die assembly. It is the
fixed part in die assembly and it is firmly fixed at the bottom. Punch die is of
rectangular in shape with rectangular ribs on bottom and on upper part a
pattern model of required shape is firmly fixed. The dimensions and material
specification is as follows.

Length = 1650 mm
5

Width = 1215 mm

Height = 160 mm

Bottom ribs = 265 * 265 mm

Material Used = High strength Steel

Density of Steel = 7.82708e-09 ton/mm^3

Poisson’s ratio = 0.27

Young’s Modula’s = 19.98 Mpa.
1.4) DIAGRAMATIC VIEW OF MODEL:
UPPERDIE
PINS
BLANKHOLDER
LOWERDIE
Figure 1.4-1: SHEET METAL DIE ASSEMBLY
6
1.5) WORKING PRINCIPLE:
Sheet Metal die casting is one of the most advance technique used in automobile
industry. This die casting assembly mainly consists of upper die, punch, blank holder,
cushion pins, guided pins and press slider. The upper die is fixed to the press slider and
punch is fixed to the ground. The blank holder, which is supported by the cushion pins,
holds the blank sheet and controls the drawing between the upper die and the punch. The
1500 ton press/die has 900 tons of drawing force by the punch and 80 tons of blank
holding force deliverable to the blank holder. The press slider transfers the drawing load
to the upper die and the cushion pins delivers the holding load to the blank holder. The
load is applied firmly until the upper die guided pins completely moves on to the blank
holder pins and once when both pins contacts together the drawing load applied is
gradually reduced. As the drawing process proceeds, the blank sheet in the blank holder
gets the shape as the pattern on the punch. In order to count for the load differences
transferred among upper die, punch and blank holder the contact boundary conditions i.e.
the pins height both on upper die and blank holder must be adjusted accordingly. Then
the blank sheet with required shape is removed and new sheet is loaded and the process
will repeat again.
7
1.6) PROBLEM DESCRIPTION:
Among the main components of sheet metal die, the role of blank holder in the generation
of the restraining forces acting on the metal sheet during the deep drawing is considered.
It is well known fact that the choice of restraining force distribution is a key point in
designing the sheet metal die. These restraining forces are mainly controlled by the height
and diameter of guided pins on upper die and blank holder. Due to the load of press
slider, large deformations are caused and big stresses are concentrated in the upper die
and blank holder. The evolution of the blank holder and upper die modeling in the finite
element simulation of the drawing process is reviewed and the need of deformable model
of the blank holder and upper die to obtain process realistic simulation is pointed out. The
factors that affect the actual restraining force distribution are briefly analyzed and also
identifying control factors like overall deformations of die.
8
1.7) TOOLS USED FOR MODELING AND FEA:
1.7.1) PRO/ENGINEER
Pro/ENGINEER mechanical design software from Parametric Technology
Corporation is used for creating 3D computer models of mechanical parts and
assemblies and the creation of 2D drawings for the models. Like any software it is
continually being developed to include new functionality. Its main aim is to outline
the scope of capabilities to give an overview rather than giving specific details on
the individual functionality of the product. Pro/Engineer is a piece of software
that falls within the category of CAD/CAM/CAE and site alongside other similar
products currently on the market. Pro/Engineer is a feature based modeling
architecture incorporated into a single database philosophy with advanced rule
based design capabilities. The capabilities of the product can be split into the three
main heading of Engineering Design, Analysis and Manufacturing. This data is
then documented in a standard 2D production drawing or the 3D drawing standard
ASME Y14.41-2003.
1.7.2) MECHANICA
Finite Element Analysis (FEA), also known as Finite Element Method (FEM), is
one of the most important tools added to mechanical design engineer’s toolkit in
recent years. Because of very powerful desktop workstations, FEA is now
available at a practical cost to virtually all engineers and designers.
9
MECHANICA is one of the many commercial systems that are available.
MECHANICA is an integrated option in Pro/ENGINEER and is actually
composed of two programs which are structural and thermal. In present paper the
structural MECHANICA analysis is used for analyzing the die assembly at
several boundary conditions.
10
Chapter 2
DESIGN USING Pro | ENGINEER
2.1) INTRODUCTION:
Pro | ENGINEER is one of the mechanical design software from Parametric Technology
Corporation which include creating 3D computer models of mechanical parts and
assemblies, and creation of 2D drawings for the models. This CAD software runs on
Microsoft Windows and UNIX platforms. Like any other software it is continually being
developed to include much new functionality. Pro/Engineer is a piece of software that
falls within the category of CAD/CAM/CAE and site other similar products currently on
the market. Pro/Engineer is a feature based modeling architecture incorporated into a
single database philosophy with advanced rule based design capabilities. The capabilities
of the product can be split into the three main heading of Engineering Design, Analysis
and Manufacturing
It is different from many other CAD tools by the following way.
 Pro/ENGINEER is a not a drafting system instead it is a three dimensional solid
modeling system.
 The 3D solid model is the ‘engineering document of record’, not the drawing.
 It is not based on X, Y and Z axis system.
 Layers and colors are not related.
 Every time we save an object, it creates a new version of the object.
11
Before we use Pro/ENGINEER we need to know some of the terminology and concepts
used.
2.2) GENERAL TERMS:
a) Parametric: Parameters are modified to affect changes in the model. A
dimension is a simple example of a parameter.
b) Feature Based: It is a set of instructions that tells the system how to create
geometry. Features are created in a logical order to convey design intent to
the system.
c) Modeling: Creating computer images coupled with geometric information
defining a part or assembly.
d) Model: It is the engineering document of record and contains all design
information including dimension, tolerances, materials, notes, symbols,
and manufacturing data. Models are two type’s i.e. part model and
assembly model.
e) Sketch: Part models are a collection of ‘sketched’ features. These sketches
define geometric design intent as the model is created.
f) Working Directory: It is the directory where all Pro/ENGINEER files are
saved.
12
2.3) GEOMETRIC TERMS:
a) Axis: It is the center of a cylinder or other revolved feature. It is used on
drawings as centerlines and also to indicate symmetry on drawings.
b) Blend: A feature that is created by blending from one shape to another.
c) Datum Plane: It is the foundation of all models. These are non-solid,
orthogonal, planar surfaces, and are used to create and orient the model’s
solid geometry. It includes three default datum planes which are Top,
Right and Front.
d) Edge: It is intersection of two part surfaces.
e) Extrude: It is used to create a sketch normal to a plane.
f) Pattern: It is used to create a series of similar features.
g) Plane: It is usually a flat object. Usually a datum plane but also can be a
solid part face or surface.
h) Point: It can be created on surfaces, at vertices, etc.
i) Revolve: This feature is used to create revolving sketch about a centerline.
j) Round: It is a fillet radius on a solid part. It can be constant or variable.
k) Sweep: It is a feature created by a sketch that follows a path or trajectory.
l) Vertex: It is intersection of three edges.
13
2.4) Pro/ENGINEER VERSIONS:
Name/Version
Build Number
Date
Pro/ENGINEER (Autofact1987premier)
R1.01
1987
Pro/ENGINEER
R 8.0
1991
Pro/ENGINEER
R 9.0
1992
Pro/ENGINEER
R 10.0
1993
Pro/ENGINEER
R 11.0
1993
Pro/ENGINEER
R 12.0
1993
Pro/ENGINEER
R 13.0
1994
Pro/ENGINEER
R 14.0
1994
Pro/ENGINEER
R 15.0
1995
Pro/ENGINEER
R 16.0
1996
Pro/ENGINEER
R 17.0
1997
Pro/ENGINEER
R 18.0
1997
Pro/ENGINEER
R 19.0
1998
Pro/ENGINEER
R 20.0
1998
Pro/ENGINEER
R 2000i
1999
Pro/ENGINEER
R 2000i2
Pro/ENGINEER
R 2001
2001
Pro/ENGINEER Wildfire
R 1.0
2002
Pro/ENGINEER Wildfire
R 2.0
2004
Pro/ENGINEER Wildfire
R 3.0
2006
Pro/ENGINEER Wildfire
R 4.0
2008
Pro/ENGINEER Wildfire
R 5.0
2009
Creo Elements/Pro
R 5.0 (as of M065)
2010
The version used in this paper is Pro/ENGINEER Wildfire 3.0 2006.
2000
14
2.5) DESIGN OF SHEET METAL DIE PARTS:
2.5.1) DESIGN OF UPPER DIE: In order to design this in pro/ENGINEER feature used
are Extrusion, sketch and planes.
Figure 2.5-1: UPPER DIE
15
2.5.2) DESIGN OF BLANK HOLDER: In order to design this in Pro/ENGINEER
features used are Extrusion, Points, Sketch, Style and Solidify.
Figure 2.5-2: BLANK HOLDER
16
2.5.3) DESIGN OF LOWER DIE PUNCH: In order to design this in pro/ENGINEER
features used are Extrusion, Pattern, Hole and Chamfer.
Figure 2.5-3: LOWER DIE PUNCH
17
2.5.4) DESIGN OF PATTERN SURFACE PART: In order to design this in
Pro/ENGINEER an important special feature is used. It is drawn by following reverse
engineering principle i.e. import feature. It is imported from other CAD software.
Figure 2.5-4: PATTERN SURFACE
18
2.5.5) DESIGN OF UPPER DIE SURFACE PART: In order to design this in
Pro/ENGINEER an important special feature is used. It is drawn by following reverse
engineering principle i.e. import feature. It is imported from other CAD software
Figure 2.5-5: UPPER DIE SURFACE PART
19
2.6 DESIGN OF SHEET METAL DIE ASSEMBLY: In order to create the assembly of
sheet metal die, initially we have to assembly the upper die and upper die surface parts
and lower die and pattern surface. Hence it is assembled in the following way.
2.6.1) ASSEMBLING UPPER DIE AND UPPER DIE SURFACE: In order to assemble
these two parts in pro / ENGINEER the assembly features like Mate and Align are used.
Figure 2.6-1: UPPER DIE ASSEMBLY
20
2.6.2) ASSEMBLING LOWER DIE AND PATTERN SURFACE: In order to assemble
these two parts in pro / ENGINEER the assembly features like Mate and Align are used.
Figure 2.6-2: LOWER DIE ASSEMBLY
21
2.6.3) DIE ASSEMBLY: Now from the models which we have i.e. Upper die assembly,
Lower die assembly and Blank holder the final die assembly is made. Lower die is kept
in bottom position and upon that Blank holder is perfectly aligned and on the blank
holder Upper die assembly is made to align perfectly so that the final assembly is made.
Figure 2.6-3: DIE ASSEMBLY
22
2.7) SHEET METAL DIE EXPLODED VIEW: Pro / ENGINEER is a perfect tool where
we can see the all parts in exploded view and also we come to know which parts are
aligned or mate together.
Figure 2.7-1: EXPLODED VIEW
23
Chapter 3
FEA ANALYSIS USING MECHANICA
3.1 INTRODUCTION:
MECHANICA is one of the integrated Finite Element Analysis tool in Pro/ENGINEER.
This software is one of the many commercial systems that are available. Mechanica is
one of the unique Finite Element Analysis tool in many ways. When operating in
integrated mode with Pro/ENGINEER, MECHANICA is actually composed of two
programs i.e. Structure and Thermal. Structural analysis is used for linear static stress
analysis, modal analysis, buckling analysis and large deformation analysis (nonlinear).Thermal analysis is used for steady state and transient thermal analysis. In present
paper the structural analysis is used for sheet metal die assembly.
3.2 PROBLEMS SOLVED USING MECHANICA:
The problems that are solved by using structure analysis are simple analysis, a parametric
study called a sensitivity analysis, and a design optimization.
a) ANALYSIS: A model is defined by some geometry by using Pro/ENGINEER
and this model is transferred into MECHANICA. The material properties are
specified, loads and constraints are applied, and one of several different types of
analysis can be run on the model.
b) SENSITIVITY STUDY: If we need to find out the overall effect on the solution
by varying one or more design parameters, MECHANICA is the perfect tool for
this case. We can do this by performing a number of similar analyses, and
24
changing the geometry of the model between each analysis. It has an automated
routine which allows specifying the parameter to be varied, and the overall range.
Then it automatically performs all the modifications to the model and calculates
results for the intermediate values of the design parameters.
c) DESIGN OPTIMIZATION: For a model by designating some design variables
from some geometric parameters, we can make MECHANICA to find the
combination of values of the design variables that will minimize some objective
function like total mass, some design constraints like maximum stress or
deflections etc and will find the optimum set of design variables automatically.
3.3 STEPS IN PREPARING AN FEA MODEL:
After importing the model into MECHANICA, there are several steps to be followed in
order to get perfect solutions. The steps are as follows.

Recognize the model type

Specifying the material properties, applied loads and model constraints

Running Auto Gem to produce finite element mesh

Solving the linear equations using solver

Compute items of interest from the solution variables

Display the results both graphically and Fringe mode.
The overall procedure can be explained by the following figure.
25
CREATE
GEOMETRY
USING Pro/E
MODEL TYPE
SIMULATION PARAMETERS
-MATERIAL PROPERTIES
-MODEL CONSTRAINTS
-APPLIED LOADS
RUNNING FINITE ELEMENT
MESH-AUTOGEM
SOLVING LINEAR EQUATIONS
COMPUTE/DISPLAY RESULTS OF
INTEREST
REVIEW
Figure 3.3-1: STEPS FOR FEA
26
3.4) SETTING UP THE MODEL IN MECHANICA: After drawing the model in
Pro/ENGINEER we are ready to launch the MECHANICA.
3.4.1) RUNNING MECHANICA: Mechanica is an integrated tool in Pro/ENGINEER. In
order to run Mechanica, from pull down menu go to Applications and then Mechanica. It
pops up a window saying the units which are used by the pro/ENGINEER. Then a
window pops up which ask us to select model type and the analysis type. So, select solid
as model type and structural analysis for analysis type.
Figure 3.4-1: MODEL SETUP
27
3.4.2) MATERIAL SPECIFICATION: Now, we have to assign the material to the parts
of sheet metal die assembly. It is a two-step process i.e. material definition and assigning
it to the part. So, in present paper the defined material is steel and it is assigned to all
parts i.e. for Upper die, Blank holder and Lower die. The following figures show the
defining material and assign materials respectively.
Figure 3.4-2: MATERIAL DEFINITION
28
Figure 3.4-3: ASSIGNING MATERIAL
29
3.4.3) APPLYING THE PRESSURE LOAD: Now a pressure load of 1000 lbm/in sec^2
is uniformly applied on the upper die. Now the model will appear similar to following
figure.
Figure 3.4-4: ASSIGNING LOAD
30
3.4.4) DEFINING DISPLACEMENT CONSTRAINTS: The Lower die part in sheet
metal die assembly is fixed to ground. In order to define that in MECHANICA we have
to assign zero displacement constraint to lower portion of Lower die. Now the model will
appear similar to following figure.
Figure 3.4-5: ASSIGNING DISPLACEMENT CONSTRAINT
31
3.4.5) DEFINING PLANAR CONSTRAINT: In order to distribute uniform load on
upper die by the pressure applied we have to define a planar constraint. This can be
shown in following figure.
Figure 3.4-6: ASSIGNING PLANAR CONSTRAINT
32
3.4.6) RUNNING BASIC STATIC ANALYSIS: Now we have to set up basic analysis
from the pull down menu by selecting Analyses and Design studies. Initially the analysis
is run using Quick check and it detects any errors in the model. Once we pass through
this step the analysis is runes again by single and multi-pass adaptive methods. The
setting up of basic analysis is shown in following figures.
Figure 3.4-7: SETTING UP BASIC ANALYSIS
33
Figure 3.4-8: RUNNING BASIC ANALYSIS
34
3.4.7) RUNNING AUTO GEM: The finite element analysis mesh is created by using
automatic mesh generator, Auto Gem in MECHANICA. After running this the main
items which we can know are number of elements created, convergence on pass,
maximum Von Misses stress, maximum displacement, CPU time and elapsed time. These
can be seen in following figure.
Figure 3.4-9: RUNNING AUTO GEM
35
3.4.8) MECHANICA CONVERGENCY: In order to converge the mesh size in
MECHANICA we have to run the basic static analysis in three ways i.e. Quick check,
Single pass adaptive and Multi pass adaptive. Quick check is done in order to check the
die assembly is properly constrained or not. Once the quick check is done then it is run in
Single pass Adaptive test in order to ensure that we get the basic deflections, stress and
strain results. Then we have to run again with Multi Pass Adaptive test by setting
maximum polynomial order to 9 and percentage of convergence to 5.Then the Auto Gem
is runned again and it calculates several equations and we get final mesh which is
converged and ready to set for the optimum design conditions.
Figure 3.4-10: SETTING UP CONVERGENCE
36
Figure 3.4-11: RUNNING MULTI-PASS ADAPTIVE TEST
Summary of Multi-Pass Adaptive test from MECHANICA program:
Mechanica Structure Version L-03-38:spg
Summary for Design Study "basic_static"
Mon Nov 15, 2010 12:21:50
-----------------------------------------------------------Run Settings
Memory allocation for block solver: 128.0
Parallel Processing Status
Parallel task limit for current run:
37
Parallel task limit for current platform:
64
Number of processors detected automatically:
2
Checking the model before creating elements...
These checks take into account the fact that Auto GEM will automatically create
elements in volumes with material properties, on surfaces with shell properties, and on
curves with beam section properties. Generate elements automatically.
Checking the model after creating elements...
No errors were found in the model.
Mechanica Structure Model Summary
Principal System of Units: Inch lbm Second (Pro/E Default)
Length:
in
Mass:
lbm
Time:
sec
Temperature:
F
Model Type: Three Dimensional
Points:
5640
Edges:
28786
Faces:
40676
Springs:
0
Masses:
0
Beams:
0
38
Shells:
0
Solids:
1765
Elements:
17650
------------------------------------------------------------Standard Design Study
Static Analysis "basic_static":
Convergence Method: Multiple-Pass Adaptive
Plotting Grid:
4
Convergence Loop Log:
(12:23:00)
>> Pass 1 <<
Calculating Element Equations
(12:23:03)
Total Number of Equations: 15324
Maximum Edge Order:
Solving Equations
Post-Processing Solution
1
(12:23:04)
(12:23:04)
Calculating Disp and Stress Results
Checking Convergence
Elements Not Converged:
(12:23:06)
(12:23:36)
17650
Edges Not Converged:
28786
Local Disp/Energy Index:
100.0%
Global RMS Stress Index:
100.0%
Resource Check
(12:23:37)
39
Elapsed Time
(sec):
CPU Time
108.64
(sec):
Memory Usage
88.34
(kb):
418453
Wrk Dir Dsk Usage (kb):
139264
>> Pass 2 <<
Calculating Element Equations
(12:23:40)
Total Number of Equations: 97787
Maximum Edge Order:
2
Solving Equations
(12:23:43)
Post-Processing Solution
(12:23:50)
Calculating Disp and Stress Results
Checking Convergence
(12:23:56)
(12:24:24)
Elements Not Converged:
4023
Edges Not Converged:
0
Local Disp/Energy Index:
100.0%
Global RMS Stress Index:
67.7%
Resource Check
(12:24:25)
Elapsed Time
(sec):
156.64
CPU Time
(sec):
121.28
Memory Usage
(kb):
Wrk Dir Dsk Usage (kb):
468541
295936
40
>> Pass 3 <<
Calculating Element Equations
(12:24:29)
Total Number of Equations: 181082
Maximum Edge Order:
3
Solving Equations
(12:24:32)
Post-Processing Solution
(12:24:53)
Calculating Disp and Stress Results
Checking Convergence
(12:25:01)
(12:25:33)
Elements Not Converged:
3770
Edges Not Converged:
0
Local Disp/Energy Index:
100.0%
Global RMS Stress Index:
61.9%
Resource Check
(12:25:35)
Elapsed Time
(sec):
226.33
CPU Time
(sec):
180.19
Memory Usage
(kb):
Wrk Dir Dsk Usage (kb):
509307
655360
>> Pass 4 <<
Calculating Element Equations
(12:25:38)
Total Number of Equations: 339702
Maximum Edge Order:
4
41
Solving Equations
(12:25:48)
Post-Processing Solution
(12:26:38)
Calculating Disp and Stress Results
Checking Convergence
(12:26:51)
(12:27:29)
Elements Not Converged:
3131
Edges Not Converged:
0
Local Disp/Energy Index:
100.0%
Global RMS Stress Index:
38.6%
Resource Check
(12:27:34)
Elapsed Time
(sec):
345.51
CPU Time
(sec):
309.33
Memory Usage
(kb):
Wrk Dir Dsk Usage (kb):
566982
1487872
>> Pass 5 <<
Calculating Element Equations
(12:27:38)
Total Number of Equations: 598057
Maximum Edge Order:
Solving Equations
Post-Processing Solution
5
(12:28:28)
(12:32:00)
Calculating Disp and Stress Results
Checking Convergence
(12:32:27)
(12:33:14)
42
Elements Not Converged:
2004
Edges Not Converged:
0
Local Disp/Energy Index:
72.9%
Global RMS Stress Index:
25.0%
Resource Check
(12:33:33)
Elapsed Time
(sec):
704.35
CPU Time
(sec):
663.48
Memory Usage
(kb):
Wrk Dir Dsk Usage (kb):
673600
3394560
>> Pass 6 <<
Calculating Element Equations
(12:33:36)
Total Number of Equations: 981628
Maximum Edge Order:
Solving Equations
6
(12:35:48)
Post-Processing Solution
(12:46:16)
Calculating Disp and Stress Results
Checking Convergence
(12:47:12)
(12:48:26)
Elements Not Converged:
1076
Edges Not Converged:
0
Local Disp/Energy Index:
54.4%
Global RMS Stress Index:
17.8%
43
Resource Check
(12:48:47)
Elapsed Time
(sec):
1618.26
CPU Time
(sec):
1648.78
Memory Usage
(kb):
783599
Wrk Dir Dsk Usage (kb):
7080960
>> Pass 7 <<
Calculating Element Equations
(12:48:51)
Total Number of Equations: 1503838
Maximum Edge Order:
7
Solving Equations
(12:54:12)
Post-Processing Solution
(13:22:10)
Calculating Disp and Stress Results
Checking Convergence
(13:24:16)
(13:26:06)
Elements Not Converged:
586
Edges Not Converged:
0
Local Disp/Energy Index:
41.7%
Global RMS Stress Index:
13.6%
Resource Check
(13:26:47)
Elapsed Time
(sec):
3897.89
CPU Time
(sec):
4129.66
Memory Usage
(kb):
953660
44
Wrk Dir Dsk Usage (kb): 13493248
> Pass 8 <<
Calculating Element Equations
(13:26:51)
Total Number of Equations: 2171995
Maximum Edge Order:
8
Solving Equations
(13:30:48)
Post-Processing Solution
(13:40:25)
Calculating Disp and Stress Results
Checking Convergence
(13:45:1
(13:50:26)
Elements Not Converged:
293
Edges Not Converged:
0
Local Disp/Energy Index:
31.2%
Global RMS Stress Index:
8.9%
Resource Check
(13:58:58)
Elapsed Time
(sec):
4987.22
CPU Time
(sec):
6129.55
Memory Usage
(kb):
Wrk Dir Dsk Usage (kb):
1053660
1843584
>> Pass 9 <<
Calculating Element Equations
(13:58:58)
Total Number of Equations: 2858445
45
Maximum Edge Order:
9
Solving Equations
(14:10:25)
Post-Processing Solution
(14:35:20)
Calculating Disp and Stress Results
Checking Convergence
(14:47:12)
(14:57:35)
Elements Not Converged:
0
Edges Not Converged:
0
Local Disp/Energy Index:
20.9%
Global RMS Stress Index:
7.5%
Resource Check
(15:10:33)
Elapsed Time
(sec):
5123.66
CPU Time
(sec):
7895.22
Memory Usage
(kb):
Wrk Dir Dsk Usage (kb):
1543680
2048657
Hence from above all passes i.e. from 1 to 9 all elements are converged and then we run
optimum design analysis.
46
3.4.8) SETTING UP OPTIMUM DESIGN STUDY: Now, the conditions which are
required to be satisfied in the design are given in optimum design study. The conditions
given are low overall displacement and the height to of pins on blank holder. The setting
up and running the optimum design study is shown in following figures respectively.
Figure 3.4-12: SETTING UP OPTIMUM DESIGN STUDY
47
Figure 3.4-13: RUNNING OPTIMUM DESIGN STUDY
48
Chapter 4
RESULTS
4.1) RESULTS FROM BASIC STATIC ANALYSIS:
 Maximum Deflections:1.667in
 Maximum Stress:324.3Mpa
 Maximum Strain:0.134
 Height of Pin:2.9526in
 Height of upperdie:21.2598in
4.2) RESULTS FROM OPTIMUM DESIGN STUDY ANALYSIS:
 Maximum Deflections:1.922e^-03in
 Maximum Stress:293.2Mpa
 Maximum Strain:1.294e^-04
 Height of Pin:2.899in
 Height of upperdie:20.99in
These results can also be seen in graphical and fringe views by MECHANCIA tool.
These are as follows.
49
4.3) BASIC STATIC Vs OPTIMIZATION-DEFLECTIONS:
Figure 4.3-1: DEFLECTIONS IN FRINGE DISPLAY TYPE
50
4.4) BASIC STATIC Vs OPTIMIZATION-STRESSES:
Figure 4.4-1: STRESSES IN FRINGE DISPLAY TYPE
51
Maximum Stress –Basic Static
Maximum Stress-Optimization
Figure 4.4-2: MAXIMUM STRESS LOCATIONS
52
4.5) BASIC STATIC Vs OPTIMIZATION-PRINCIPAL STRAIN:
Figure 4.5-1: PRINCIPAL STRAIN IN FRINGE DISPLAY TYPE
53
Maximum Strain-Optimization, Basic Static
Figure 4.5-2: MAXIMUM PRINCIPAL STRAIN LOCATIONS
54
4.6) DIMENSIONAL CHANGES IN DIE ASSEMBLY: After running optimum design
study we get the dimensional changes in height of pins and upper die and these can be
shown in following figure.
Figure 4.6-1: DIMENSIONAL CHANGES IN DIE ASSEMBLY
55
4.7) GRAPHICAL RESULTS: The graphical results in MECHANICA can be known by
considering certain area in sheet metal die assembly. In present paper the top surface of
the blank holder is considered one of the areas where we interested to see graphical
results. The area we considered can be shown in following figure.
Figure 4.7-1: GRAPHICAL AREA CONSIDERED
The deflections at this area for basic static analysis and optimization can be viewed in
following figure.
56
Figure 4.7-2: DEFLECTIONS IN GRAPHICAL DISPLAY TYPE
57
4.8) OPTIMIZED AUTO GEM: After optimization the auto gem is runned again and the
result can be seen in following figure.
Figure 4.8-1: AUTO-GEM AFTER OPTIMIZATION
58
Chapter 4
FEATURE WORK
 Modification in designing to make it more robust.
 Finite Element Analysis of complete sheet metal die assembly including blank
sheet and pattern.
 Vibration Analysis.
 Using any other FEA tool in getting more appropriate results.
59
REFERENCES
1. Pro | ENGINEER WILDFIRE 3.0 BASIC DESIGN
Steven G.Smith
2. Pro | ENGINEER WILDFIRE 3.0 MECHANICA TUTORIAL
Roger Toogood, SDC PUBLICATIONS
3. www.wikipedia.com