Simulation Techniques in Manufacturing Technology Introduction

Laboratory for Machine Tools and Production Engineering Chair of Manufacturing Technology

Prof. Dr.-Ing. Dr.-Ing. E.h. Dr. h.c. Dr. h.c. F. Klocke © WZL/Fraunhofer IPT

Outline 1

Lecture organisation

2

Presentation of WZL

3

Lecture objectives

4

Modelling and simulation: Definition, motivation and integration

5

Lecture topics and fundamental knowledge

6

FE modelling for the forming process

7

FE modelling for the cutting process

8

FE model validation

9

Optimization integration in the FEM

© WZL/Fraunhofer IPT

Seite 2

STMT-Lecture: Time schedule Date Typ 21. Okt L

Room No. Lecturer 53C/101 Abouridouane 53B, R312b

Topic Introduction to STMT

28. Okt 28. Okt

L E

53C/101 Ozhoga-Maslovskaja 53C/101 54A, R411

Forming technology basics

04. Nov

L

53C/101 Ozhoga-Maslovskaja 54A, R411

Actual simulation techniques in forming process

11. Nov.

L

53C/101 Ozhoga-Maslovskaja 54A, R411

Bulk metal forming

18. Nov 18. Nov

L E

53C/101 Ozhoga-Maslovskaja 53C/101 54A, R411

Sheet metal forming and separation

25. Nov 25. Nov

L E

53C/101 Abouridouane 53C/101 53B, R312b

Principles of Cutting

02. Dez 02. Dez

L E

53C101 Abouridouane 53C/101 53B, R312b

Overview of the various cutting processes

09. Dez

L

53C/101 Abouridouane 53B, R312b

FE-Simulation of cutting processes

16. Dez 16. Dez

W W

53B/101a Abouridouane 53B/101a Ozhoga-Maslovskaja

FEM-Workshop (Abaqus and Deform)

13. Jan 13. Jan

L E

20. Jan 20. Jan

53C101 53C101

Barth 54A, R403

Cutting with geometrically undefined cutting edge I

L E

53B/101a Barth 53B/101a 54A, R403

Cutting with geometrically undefined cutting edge II

27. Jan 27. Jan

L E

53B/101a Abouridouane 53B/101a 53B, R312b

Methods of validation and optimization techniques

03. Feb 03. Feb

L E

53C/101 Abouridouane 53C/101 53B, R312b

Revision of contents

© WZL/Fraunhofer IPT

Time: Lecture (L): Fr, 10.00-11.30h Exercise (E): Fr, 11.45-12.30h Location:

WZL, RWTH Aachen Herwart-Opitz-Haus Steinbachstr. 53 52074 Aachen

Room:

53C, 101

Contact:

Dr.-Ing. M. Abouridouane Tel. (0241) 80-28176

Seite 3

STMT-Lecture: Exam, computer exercise, literature  Examination – Type of examination: Oral – Date of the examination: February, the xxth 2017 – Room, time, and distribution of groups will be given! – Duration: 60 minutes for each group  Computer exercise – Date for the FEM-Workshop: December, the 16th 2016 – Room: 53B/101a (WZL, Herwart-Opitz-Haus) – Time: 10:00 to 18:00  Literature about metal machining (Emails list!) – Manufacturing processes 1 - Cutting of Klocke – Metal Machining (Theory and Applications) of Childs – Machining Dynamics of Kai Cheng  Any other discussion points, comments or questions? – Please contact Mr. Abouridouane (Tel.: +49 241 80-28176) © WZL/Fraunhofer IPT

Seite 4

STMT-Lectutre: Supervisors

 Cutting process

Dr.-Ing. Mustapha Abouridouane Herwart-Opitz-Haus 53B 312b Tel.: +49 241 80-28176 Fax: +49 241 80-22293 [email protected]

 Forming process

Dr.-Ing. Oksana Ozhoga-Maslovskaja Herwart-Opitz-Haus 54A 411 Tel.: +49 241 80-27428 Fax: +49 241 80-22293 [email protected]

 Grinding process

M.Sc. RWTH Sebastian Barth Herwart-Opitz-Haus 54A 403 Tel.: +49 241 80-28183 Fax: +49 241 80-22293 [email protected]

© WZL/Fraunhofer IPT

Seite 5

Outline 1

Lecture organisation

2

Presentation of WZL

3

Lecture objectives

4

Modelling and simulation: Definition, motivation and integration

5

Lecture topics and fundamental knowledge

6

FE modelling for the forming process

7

FE modelling for the cutting process

8

FE model validation

9

Optimization integration in the FEM

© WZL/Fraunhofer IPT

Seite 6

RWTH Aachen and Fraunhofer-Gesellschaft Fraunhofer-Gesellschaft  More than 65 institutes und facilities at 40 locations in Germany  >23,000 employees  approx. € 2.0 billion research funds per year, € 1.7 billion through research contracts  3 institutes in Aachen RWTH Aachen University  Founded in 1870  40,375 students Faculty of Mechanical Engineering  11,700 students (incl. 2,700 first year students)  53 professors  2,600 employees  170 graduates per year © WZL/Fraunhofer IPT

Seite 7

Production Technology in Aachen Laboratory for Machine Tools and Production Engineering (WZL)  RWTH Aachen University institute  Founded in 1906  839 employees  16,000 m² offices and laboratories

Fraunhofer Institute for Production Technology IPT  Fraunhofer-Gesellschaft institute  Founded in 1980  450 employees  6300 m² offices and laboratories  Certified to DIN EN ISO 9001:2008

© WZL/Fraunhofer IPT

Seite 8

Budget 2013: WZL, Fraunhofer IPT, WZLforum, WZL Aachen GmbH Budget: 53.61 Mio €

Industrial projects

41.70 %

Public funding*

33.57 %

Basic funding by Fraunhofer-Gesellschaft and RWTH Aachen University

24.73 %

* EU, AiF, BMBF, DFG © WZL/Fraunhofer IPT

Seite 9

Two Institutes – One Philosophy

 Manufacturing Technology  Process Technology  Production Machines  Mechatronic Systems Design  Production Quality and Metrology  Technology Management © WZL/Fraunhofer IPT

 Gearing Technology  Machine Tools  Metrology and Quality Management  Production Engineering and

Production Management Seite 10

Our Focus Process Technology  Machining and material removal processes  Laser materials processing  Forming processes  CAx, Virtual Reality

Production and Machine Tools  Design of production machines and components  Control technology and automation  Component and production machines testing

Metrology  Tactile metrology  Optical metrology

© WZL/Fraunhofer IPT

Gearing Technology  Gear manufacturing  Gear calculation and investigation

Management  Business Engineering  Technology management  Innovation management  Production management  Quality management

Education  Professional training  Executive MBA for Technology Managers  Conferences, congresses, seminars

Seite 11

Process and Manufacturing Technology Prof. Dr.-Ing. Dr.-Ing. E.h. Dr. h.c. Dr. h.c. Fritz Klocke

Grinding and forming

Cutting technology

Turning, milling, drilling, broaching

Grinding, lapping, polishing, honing

Solid forming, sheet metal forming, hard smooth rolling, tribology

Joining, cutting, forming

Laser machining

CAx technologies

Laser surface treatment

CAD/CAM technologies

Rapid Manufacturing

Process and product monitoring

Process monitoring systems and strategies

Material removal processes

Tool and die making Precision and micro technology Optics and optical systems Plant engineering and construction Automotive, aerospace, turbine construction

© WZL/Fraunhofer IPT

Seite 12

Process and Manufacturing Technology  Manufacturing fundamentals  Machining with a geometrically defined cutting edge  Machining with a geometrically undefined cutting edge  Material removal processes  Forming processes

 Laser machining  Gearwheel manufacture  Precision and ultra-precision processes

 Process and product monitoring  Process simulations, methods and tools for technology

planning and production design, virtual reality

© WZL/Fraunhofer IPT

Seite 13

Manufacturing Technology: Group: Fundamentals of Cutting & Modeling and Evaluation Fundamentals of Cutting Machinability

Analysis of wear

Process Design

Modeling and Evaluation

Tool Concept for Energy-saving development production cooling

Technology planning

lubricants

Bild

Bild

Modelling and model development

Simulation of tool wear

Bild

Space- and aircraft-industry, turbine construction (machining of turbine disks and blades, structural components..) Automotive industry (processing of crankcase, cylinder head, cylinder, camshaft, axle parts…)

Tool technology (wear analysis, tool layout, macro , micro geometry…) Materials manufacturer (machinability, lead substitute …)

Resource efficiency (material, energy, auxiliaries…) © WZL/Fraunhofer IPT

Seite 14

Chair of Manufacturing Technology Group Fundamentals of Cutting   









Analysis of the machinability Material analysis of tools and components, analysis of tool wear Process development and process optimisation in turning, milling, drilling, broaching, tapping Development of machining strategies, HSC and HPC machining, circular processes Development and optimisation of lubricooling strategies: dry, MQL, conventional wet, high-pressure and cryogenic Tool development: substrate, macro and micro geometry, cutting edge preparation, coating, chip form geometry Development of environmentally friendly and resource efficient machining processes

© WZL/Fraunhofer IPT

Virtuelle Realität

Seite 15

Chair of Manufacturing Technology – Modelling and Evaluation of Cutting Processes

Makroskopisches FEM-Modell

Modelling of cutting processes 

Development of process models for cutting technologies



Simulation of the thermo-mechanical load spectrum during machining



Cutting tool design and optimization of process parameters using FEMsimulations

Evaluation of cutting processes 

Acquiring and assessing of energy and material consumptions of single processes (indicators)



Evaluation and design of processes and technology chains in respect to energy and resource efficiency



F

Makrogeometrie nach der spanenden Bearbeitung

Simulation of cutting processes

Input

Ecological life cycle management and Life cycle assessment (LCA)

© WZL/Fraunhofer IPT

T(

Calculation of the workpiece distortion

Selection Werkzeuggeometrie Werkstückgeometrie TCP, vc und f

Durchdringung Energy and material measurement and assessment

Metho

Energetic and environmental Virtuelle Realität Berechnung des Spanungsque evaluation of cutting processes

der Durchdringung von W Seite 16

Outline 1

Lecture organisation

2

Presentation of WZL

3

Lecture objectives

4

Modelling and simulation: Definition, motivation and integration

5

Lecture topics and fundamental knowledge

6

FE modelling for the forming process

7

FE modelling for the cutting process

8

FE model validation

9

Optimization integration in the FEM

© WZL/Fraunhofer IPT

Seite 17

Lecture objectives  Fundamentals and basic knowledge in manufacturing

technology for a better understanding of the mechanisms during metal machining

 Modelling approachs for simulation

 Simulation techniques

 Application of simulation in manufacturing technology

 Challenges of simulation and future developments

© WZL/Fraunhofer IPT

Seite 18

Outline 1

Lecture organisation

2

Presentation of WZL

3

Lecture objectives

4

Modelling and simulation: Definition, motivation and integration

5

Lecture topics and fundamental knowledge

6

FE modelling for the forming process

7

FE modelling for the cutting process

8

FE model validation

9

Optimization integration in the FEM

© WZL/Fraunhofer IPT

Seite 19

Modelling – a human property Experience

Model vision

Perception

© WZL/Fraunhofer IPT

Seite 20

Modelling – a human property Reality / Perception

Mind

Modeling

Sensorium

IT-based converting

© WZL/Fraunhofer IPT

Seite 21

Basic of reasons

Modeling based on experience

Deductiv

Inductive reasoning

Inductiv

The particular Reality

Deductive reasoning Modeling based on theoretical derived models

The general Model section

© WZL/Fraunhofer IPT

Seite 22

Definitions Model A model is an abstract system that corresponds to a real system and is used for expensive and/or impossible - investigations, - calculations and - explanations or demonstration purposes. It delivers general information about -

elements, structure and behavior

of a part of the reality.

Simulation A simulation is a replication of a dynamic process based on a model. © WZL/Fraunhofer IPT

Seite 23

Motivation  Product – innovative – reliable – cost-effective

 Components – high quality – high precision – long product life

 Manufacturing process – economic – reproducible – flexible Continuously increasing demands of the market lead to increasing requirements for manufacturing processes. © WZL/Fraunhofer IPT

Seite 24

Why process modelling? Increase quality

Manufacture complex parts

Increase reliability of production Reduction of time required for training

Reduction of lead time

Quality

Car Body Time

Cost

Reduction of pre production trials

Apply new materials (Al, Mg, …) Use material more efficiently

Reduction of tool cost

Source: BMW © WZL/Fraunhofer IPT

Seite 25

Design of car exterior

Software solution

Application

Process chain

Integration of process modelling into the process chain Part design

Means of production Planning

Tool design

Tool manufacturing and testing

Part production

Sheet metal forming simulation Part evaluation

Process optimisation

Methods applied:

Methods applied:

- 2D modelling - one-step modelling - modelling with membrane elements Short computation time with sufficient precision

- Simulation with membrane elements - Simulation with shell elements High Precision within acceptable computation times

Source: BMW © WZL/Fraunhofer IPT

Seite 26

Modelling and Simulation: aims and requirements Goals

Today without process simulation

 Increase of the process

4

knowledge & comprehension  Prediction of the process

concept design and choice of material

12

stability  Prediction of the component

FEM-Calculation

characteristics

16

 Reduction of planning and

lay-out manufacturing aspects

development steps

8

 Cost reduction

76 Weeks

design

manufacturing planning

24 Manufacturing tests

12 © WZL/Fraunhofer IPT

specification sheet product

manufacturing workpiece test Seite 27

Modelling and Simulation: aims and requirements Future

Goals

specification sheet product

with process simulation

 Increase of the process

4

knowledge & comprehension  Prediction of the process

concept design and choice of material

12

stability  Prediction of the component

14

characteristics

FEM

 Reduction of planning and  Cost reduction

design

54 Weeks

development steps

lay-out

12

Simulation

manufacturing planning 12

manufacturing workpiece test

Reduction of the cycle time by 30% © WZL/Fraunhofer IPT

Seite 28

Modelling and Simulation: aims and requirements Goals  Increase of the process

knowledge & comprehension

High result quality

 Prediction of the process

stability

High process reliability

 Prediction of the component

characteristics  Reduction of planning and

Requirements

development steps  Cost reduction

Adaption of technological innovations Realistic prediction of the process results

© WZL/Fraunhofer IPT

Seite 29

Partitioning of different model types from literature review

Basic & regression models 20 %

ANN models 4%

Rule & knowledge models 6% Overview article 2 %

MD - models 1%

Analytical models 38 % FEA - models 19 % kinematic geometrical models 10 % Source: Heinzel 2009 © WZL/Fraunhofer IPT

Seite 30

The history of the development of cutting process models The use* Analytical models:

38%

Basic and regression models:

20%

FEA models:

19%

Kinematic geometrical models:

10%

Rule and knowledge models:

6%

ANN models:

4%

Overview article:

2%

MD models:

1%

3D, Empirical, Mechanistic 3D, Analytic 2D, FEM

2D, Thick zone, Slip-line 2D, Thin Zone, Analytic

1937

1947

1957

1967

1977

1987

1997

Source: Ivester, 50th CIRP General Assembly, Sidney 2000; *Heinzel 2009 © WZL/Fraunhofer IPT

Seite 31

Outline 1

Lecture organisation

2

Presentation of WZL

3

Lecture objectives

4

Modelling and simulation: Definition, motivation and integration

5

Lecture topics and fundamental knowledge

6

FE modelling for the forming process

7

FE modelling for the cutting process

8

FE model validation

9

Optimization integration in the FEM

© WZL/Fraunhofer IPT

Seite 32

Sheet Metal Forming Techniques

Stretch forming

Spinning

Deep drawing

Ironing © WZL/Fraunhofer IPT

Bending

Hydroforming Seite 33

Forming process: Extruding a transmission shaft

© WZL/Fraunhofer IPT

Seite 34

Face milling

© WZL/Fraunhofer IPT

Seite 35

Grinding process

© WZL/Fraunhofer IPT

Seite 36

Grinding process

© WZL/Fraunhofer IPT

Seite 37

Lattice Types of an Unit Cell face-centred cubic (fcc)

body-centred cubic (bcc)

hexagonal (hex)

γ-Fe, Al, Cu

α-Fe, Cr, Mo

Mg, Zn, Be

sliding planes:

4

6

1

sliding directions:

3

2

3

sliding systems:

12

12

3

very good

good

poor

examples:

formability: © WZL/Fraunhofer IPT

Seite 38

Stress Determination Depending on Load tensile test

shear test

compression test

F

A1

F l1

A0

F

a

q

A1

l0

l0

l l1

F

A0

F   A0 tensile stress © WZL/Fraunhofer IPT

F

F   A0 compression stress

F

A0

F  A0 shear stress Seite 39

Strain Determination of an Idealized Upsetting Process true strain (plastic) l

1 dl dl l d      ln 1 l l l0 l0

l l0

 x  ln 1 ;  y  ln

b1 h ;  z  ln 1 b0 h0

including of volume constancy l 0  h0  b0  l1  h1  b1  const.

 x   y  z  0 engineering strain (elastic) 1 dl dl l  l l d x   x    1 0  l0 l l0 l0 l0 0

l

© WZL/Fraunhofer IPT

connection between true strain - engineering strain

l  l u   l  l   l l    ln   0   ln ( x  1)  x  ln  1   ln  0 x   ln  0  l0   l0   l0   l0 l0  Seite 40

Stress-Strain Curve up to the Uniform Elongation true tensile stress:

F stress

(related to real section)

σ‘ σ

Rm

 

F A

l A

l

l0

Re ,se

engineering stress: load relieving

(related to starting section) reload

A0

 

epl

eel

F A0

strain

F © WZL/Fraunhofer IPT

Seite 41

Flow stress kf

Flow curve

Required stress to overcome strain hardening

Minimal required stress for initial plastic deformation

True strain  © WZL/Fraunhofer IPT

Seite 42

Stress conditions with corresponding Mohr's stress circles

Uniaxial

Biaxial

Triaxial

© WZL/Fraunhofer IPT

Seite 43

Yield criteria  Shear stress hypothesis by Tresca

𝜏

𝜎2 = 𝜎3 = 0 𝜎1 =

𝐹 𝐴

= 𝑘𝑓 = 2𝑘

with 𝜏𝑚𝑎𝑥

𝜏𝑚𝑎𝑥 = 𝑘

kf 2

k=

𝜎1 − 𝜎3 = 𝑘𝑓

𝜎3

𝜎1

𝜎

1 𝑘𝑓 = max( 𝜎1 − 𝜎2 , 𝜎2 − 𝜎3 , 𝜎3 − 𝜎1 ) 2  Form change – Energy hypothesis by von

Mises 𝑘𝑓 =

© WZL/Fraunhofer IPT

1 𝜎 − 𝜎2 2 1

2

+ 𝜎2 − 𝜎3

2

+ 𝜎3 − 𝜎1

2

Seite 44

Levy-Mises flow rule Elastic

Plastic

Hooke‘s law:

Levy-Mises flow rule:

Mathematical dependence between stress and strain.

Mathematical dependence between yield stress and strain rate. The strain rate tensor and the deviatoric stress tensor are proportional to each other (λ = proportionality factor).

1 1    1 E

d1  d  1   m 

stress σ

yield stress kf

Flow rule:



d2  d  2   m 

d3  d  3   m 

Alternative form (division by dt): 1   1   m  2   2   m  3   3   m  Proportionality factor λ (not constant):   f (k f ,  )



Out of flow rule and v. Mises yield criterion follows: strain εel

© WZL/Fraunhofer IPT

plastic strain φV

 

1 3 2 1  22  32   kf 2

Seite 45

Yield stress and yield criterion F F σt

F

σz σr

σr

σt σz

Real process (multiaxial)

Determination of flow curves (uniaxial)

kf

Assumption for plastic flow (v. Mises) kf

 1   2 2   2   3 2   3   1 

2

V  k f 

Yield stress

2

σV σV Equivalent stress

Yield criterion

σV = k f © WZL/Fraunhofer IPT

Seite 46

Forming Property: Measuring Grid Technique

b  ln

b1 d0

l  ln

l1 d0

 Deformation of the measuring grid because of tensile and compression stresses inside

the sheet metal while forming  The effective strain can be derived from the grid deformation = maximum deformation

(forming limit) © WZL/Fraunhofer IPT

Seite 47

Forming Property: Forming Limit Curve Definition: φ1 > φ2 Test conditions: deep drawing test with hemispherical stamp and straight strip

Strain φ1

“Failure “ Tensocompressive

“Well“

Quelle: ThyssenKrupp

Tenso-tenso

Variable strip thickness to vary φ2 (one test corresponds with one value of φ2) Material: RR St 1403 Sheet thickness : 1 mm

Strain φ2

 Determination of forming limit curve

to predict failure by using FEM © WZL/Fraunhofer IPT

Seite 48

Outline 1

Lecture organisation

2

Presentation of WZL

3

Lecture objectives

4

Modelling and simulation: Definition, motivation and integration

5

Lecture topics and fundamental knowledge

6

FE modelling for the forming process

7

FE modelling for the cutting process

8

FE model validation

9

Optimization integration in the FEM

© WZL/Fraunhofer IPT

Seite 49

Considerations prior to a FE simulation study (Forming process) Definition of the simulation problem  Objective of the simulation study  Relevant physical mechanisms: – Mechanical, thermal, electro-magnetic…  Type of the problem: – Linear – Non-linear  Time dependency: – Static – Dynamic  Simulation software & hardware: – Solvers for the intended objectives – Element types – Specific numerical technologies © WZL/Fraunhofer IPT

Constituents of a model  Geometry – Accurate form reproduction – Stock or special FE mesh generator – Critical areas, complex shapes

 Material – Material model formulation – Elasticity and Poisson’s ratio – Density, hardening – Thermal properties  Boundary conditions – Process parameters – Process kinematics – Process steps Seite 50

Procedure of FE-Analysis CAD-model

Idealization

Pre-processor

Discretization Boundary conditions

Solver

FE-Analysis

Post-processor

Interpretation of the results

© WZL/Fraunhofer IPT

 11   G11   G  22   12   12    0      23   0   13   0

G12 G22 0 0 0

0 0 G33 0 0

0 0 0 G23 0

0    11  0   22  0   12    0   13  G13   23 

Seite 51

FE Study process CAD model Idealization Discretization Boundary conditions

Material modeling FE-Analyses Evaluation © WZL/Fraunhofer IPT

Geometry of a workpiece and a tool. Often available as CAD Data. Universal formats for 3D data (STEP, STP, STL…) Simplification of the real geometry for a more structured mesh Meshing of an object into discrete domains

Numerical reproduction of mechanic, kinematic, contact, electro-magnetic, thermal conditions of a real process

Numerical formulation of relevant material properties (elasticity, plasticity, shear etc.) Calculation of elementary matrices, definition of the system matrix and a vector of outer forces, solution of linear equation systems for every integration point Analysis of the results and answering the objective of the study

Seite 52

Simulation of bulk metal forming processes

Chronology of FEM-Simulation: Material modelling  Description of material behavior using

mathematical material models

CAD model

 Use of ideal-plastic material model is sufficient for

bulk metal forming processes

Idealization

Material modelling

Evaluation

Nominal strain ε

Plastic with hardening Nominal strain ε

© WZL/Fraunhofer IPT

Ideal plastic

Nominal strain ε Stress σ

Stress σ

Postpro. Solver

FE-Analyses

Elastic

Stress σ

simulation of sheet metal forming processes Stress σ

Boundary conditions

Preprocessor

Discretization

 Use of elastoplastic material models for

Elasto-plastic with hardening Nominal strain ε Seite 53

Simulation of bulk metal forming processes

Chronology of FEM-Simulation: FE-Analysis  Implicit solution method:

CAD model

Discretization Boundary conditions

Preprocessor

Idealization

– Small number of time steps (respectively long time increments) – Higher effort for iterations compared to explicit solution method – Often less computation time then with explicit solution method – Applicable especially for static and quasi-static problems  Explicit solution method:

FE-Analyses Evaluation © WZL/Fraunhofer IPT

Postpro. Solver

Material modelling

– Length of increment depends on the speed of sound c, Young‘s modulus E and material density ρ; this requires a high number of increments – Longer computation time compared to implicit solution method – Applicable especially for highly dynamic problems (e.g. crash-simulations) Seite 54

Simulation of bulk metal forming processes

Movie: FEM-Simulation cross joint Degree of damage

Effective stress

Mean stress

True strain

Velocity field

CAD model Idealization Discretization Boundary conditions

Material modelling FE-Analyses Evaluation

 Typical evaluation variables are stress-strain-profiles or characteristic values such as the degree of damage.

© WZL/Fraunhofer IPT

Seite 55

Outline 1

Lecture organisation

2

Presentation of WZL

3

Lecture objectives

4

Modelling and simulation: Definition, motivation and integration

5

Lecture topics and fundamental knowledge

6

FE modelling for the forming process

7

FE modelling for the cutting process

8

FE model validation

9

Optimization integration in the FEM

© WZL/Fraunhofer IPT

Seite 56

The great challenges of the cutting process Process

Strain

Strain rate / s-1

Thomolog

Extrusion

2–5

10-1 – 10-2

0.16 – 0.7

Forging / Rolling

0.1 – 0.5

10 – 10+3

0.16 – 0.7

Sheet metal forming

0.1 – 0.5

10 – 10+2

0.16 – 0.7

Cutting

1–5

10+3 – 10+6

0.16 – 0.9

Cutting process

Extreme conditions in the cutting process Source: Jaspers © WZL/Fraunhofer IPT

Seite 57

Influence factors on the cutting process Bild eines Prozesses

Workpiece µ-structure

Cutting condition Chip formation mechanisms

Texture Material properties Hardness Residual stress

© WZL/Fraunhofer IPT

Tool Cutting material

Machine Machine design

Coating Cooling lubricant Geometry Cutting parameters Contact conditions e. g.: Friction, heat transfer, wear, etc.

Drive unit M

Tool holder

Clamping device

Seite 58

Input and output parameters of the cutting simulation Chip Formation temperatures stresses deformations strain rate kind of chip chip flow chip breakage

Workpiece / Tool geometries material data contact conditions boundary conditions cutting conditions © WZL/Fraunhofer IPT

Tool strain stresses temperatures process forces wear Workpiece strain temperatures deformation burr formation distortion prospective: residual stresses, surface qualities, like: roughness, dimensional- and formdeviation Seite 59

Tool geometry modelling for a realistic tool CAD model Drilling tool

Acquisition of tool geometry Real tool

FE-CAD-Model CAD-Model

Macrogeometry

4 mm

Microgeometry

6 µm © WZL/Fraunhofer IPT

6 µm Seite 60

Definition of element type

© WZL/Fraunhofer IPT

Seite 61

Material law to calculate stresses

   Bi  u i

© WZL/Fraunhofer IPT

Seite 62

Thermo-mechanical behavior of material

   ( ,  , T )

Strain Hardening

Strain Rate Hardening

450

Thermal Softening 450

450 -3 -1

d/dt=10 s & T=20°C

=0.1 & T=20°C

=0.1 & d/dt=1s

 , MPa

400 400

300

350

150

-1

350

300

250

AA6063-T6 200

0

0.1

Source: Diss- Abouridouane

Quelle: Diss-Abouridoaune © WZL/Fraunhofer IPT

0.2

, -

AA6063-T6 0.3

0.4

300 -3 10

AA6063-T6 0

-1

10

1

3

10

d/dt , s

10 -1

0

100

200

300

400

500

T , °C Seite 63

Constitutive material modelling for the FE cutting simulation m

 T  Tr    (A  B  )  (1  C ln( / 0 ))  (1    )  Tm  Tr  Thermal softening

 Empirical models: e.g. Johnson-Cook-Modell

n

Strain hardening

Strain rate sensitivity

 Micro mechanical models: e.g. enhanced Macherauch-Vöhringer-Kocks-model 1/ q 1/ p

  kT 0      a    1   ·ln      G 0      * 0

   

 

Athermal processes

Damping process

Thermal activated processes  Semi-empirical models: e.g. Zerilli-Armstrong-model for bcc-materials

σ = ΔσG + C1 exp -C2T + C3T ln()  + C4 n + C5 L-1/2

Initial density of dislocations Source: Diss-Abouridouane © WZL/Fraunhofer IPT

Influence of temperature and strain rate

Dislocation jam

Influence of grain size Seite 64

Determination of High speed flow curves Split-Hopkinson-Pressure-Bar Projectile Projektil

TemperierTemperature chamber kammer

Eingangsstab Input rod

Output rod Ausgangsstab

Tube Rohr Bearing Lager

Air cylinder Preßluftbehälter Joke Joch

Rohr Tube

Sample Probe

Projectile Projektil

Deckel mit Cover with air Luftanschluss

Eingangsstab Input rod Tensile specimen Zugprobe

Ausgangsstab Output rod

Lager

Bearing

Pressluftbehälter Air cylinder with mit Schnellöffnungsventil quick release valve © WZL/Fraunhofer IPT

Auffangbehälter Collection bag

Split-Hopkinson-Tension-Bar

connection

Source: LFW

Bearing Lager

Bearing Lager Strain rate:

500 s-1 – 10000 s-1

Temperature range:

93 K – 1273 K

Projectile speed:

2,5 m/s – 50 m/s

Projectile mass:

m = 3,15 kg Seite 65

Material law for high strain rate deformation

K B       1  a  K ( B   )n    dt n

ad





800

True w SpannungMPA , MPa ahreStress,

kf

AA7075 T7351 DPressure ruckversutests che

K = 960 MPa B = 0.031 n = 0.182 -6  / K = 6.25·10 s

700 d / dt =-1 5010 s-1 4889 s-1 4350 s-1 4294 s-1 3450 s-1 3439 s-1 2558 s-1 2529 s -1 0.001 s

600 500 400

0

0.2

Lines: Calculation Symbols: o experiments : r

0.4

0.6

0.8

True plastic strain, -

Source: Diss- Brodmann Quelle: Diss-Brodmann © WZL/Fraunhofer IPT

Seite 66

Material damage mechanisms Type of load Shear loading

Tensile loading

TiAl6V4

20 µm

Shear localisation model (Imperfection theory)

20 µm

Void growth model (Hancock-Mackenzie)

Quelle: Diss-Abouridouane © WZL/Fraunhofer IPT

Seite 67

Damage modelling for the FE cutting simulation (ductile failure) 

 Macromechanical damage models – Effective stress / effective strain model: – Gosh-Model: – Ayada-Model:

Dσ = σv,f / Dε = εv,f DGosh = (1+σ2/σ1) σ12 dD = (σm/σv) dεv

0 E

 Micromechanical damage models (Void expansion models) – Hancock-Mackenzie-Model

 3 σm  ε f = ε n + α exp    2 σv 

εf

2

– Gurson-Tveergard-Needleman-Model

– Johnson-Cook-Model Source: Diss-Abouridouane © WZL/Fraunhofer IPT

 σV   3σ m  2   0= + 2fq cosh 1+ q f      1 1 σ   2σ    V,M V,M    

   ε   σm   T ε f =  D1 + D2exp  -D3   1+ D4ln    1+ D5  σ ε T     v   m    0   Seite 68



Friction modelling for the FE cutting simulation Thermal load on the tool-workpiece interface Temperature distribution on the contact zone

workpiece structure

5 1 3 2

4

rake face cut surface primary shearing zone turning tool secondary shearing zone of the face seperative zone (stagnation point) secondary shearing zone of the flank preliminary deformation zone

© WZL/Fraunhofer IPT

300

Chip

310

400 450 500

600 650

flank

1 2 3 4 5

(by Kronenberg)

shearing Workpiece plane chip structure 380 ºC 130 80 500 30

vc

600 Workpiece material: Yield strength: Cutting material: Cutting speed: Uncut chip thickness: Rake angle:

700 Tool Steel kf = 850 N/mm2 HW-P20 vc = 60 m/min h = 0,32 mm o= 10º Seite 69

Friction modelling for the FE cutting simulation Deformation on the tool-workpiece interface workpiece structure shearing plane chip structure

vc

5

shearing zone 0,1 mm

1 3 2

4

flank rake face cut surface 1 2 3 4 5

primary shearing zone turning tool secondary shearing zone of the face seperative zone (stagnation point) secondary shearing zone of the flank preliminary deformation zone

© WZL/Fraunhofer IPT

turning tool cut surface workpiece material: cutting edge material: cutting speed: cross-section area of cut:

C53E HW-P30 vc = 100 m/min ap x f = 2 x 0,315 mm2 Seite 70

Friction modelling for the FE cutting simulation Mechanical load on the tool-workpiece interface workpiece structure shearing plane chip structure

vc

5

Normal stress:

1 3

Shear stress:

2

4

flank rake face cut surface 1 2 3 4 5

primary shearing zone turning tool secondary shearing zone of the face seperative zone (stagnation point) secondary shearing zone of the flank preliminary deformation zone

© WZL/Fraunhofer IPT

Contact zone Tool by Oxley und Hatton

Seite 71

Friction modelling for the FE cutting simulation R  Coulomb friction model: Coulomb friction  R    N Shear friction

 Shear friction model:

Reality

R  m k

with

k

kf 3

 Transition from sliding friction (Coulomb) to

Sliding

R

N

Sticking

Orowan / Özel Reality

Usiu Shaw / Wanheim und Bay

N © WZL/Fraunhofer IPT

sticking friction (Shear): Z.B.: Usui-Model

τR

– Friction shear stress

N

– Normal stress

k

– Von Mises flow shear stress

kf

– Von Mises flow stress

µ, m – Friction coefficients Seite 72

Wear modelling for the FE cutting simulation Wear typs on the tool cutting edge and wear mechanisms Chip

Rake face

Tool Crater wear

Cutting edge breakouts Tool cutting edge

Crater wear

Flank face

Built-Up-Edge

Flank wear Flank wear

Workpiece

Oxidation

Sliding mechanisms Abrasion © WZL/Fraunhofer IPT

Adhesion

No sliding mechanisms Delamination

Diffusion

Electrochemical

Oxidation Seite 73

Tool wear modelling tool wear modelling

tool life equations tool life by Taylor:

T  v ck  Cv T = tool life  = temperature

tool wear rate models

tool life by Hasting:

T 

empirical tool wear model

A

B

k, A, B = constants Cv = T for vc = 1 m/min model by Archard:

Adhesion / dV F S  K Abrasion dt 3H

© WZL/Fraunhofer IPT

Abrasion + Diffusion Adhesion model by Takeyama:

model by Usui: C

( 2 ) dV  σ n  v ch  C1  e T dt

dV/dt = wear volume per time H = hardness F = mechanical load S = cutting path

physical tool wear model

E dV  G  v c  D  e R dt 

K, C1, C2, G, D = constants n = normal pressure vch = sliding velocity  = temperature Seite 74

FEM Software Solution for FEM simulation of the Cutting Process

MSC.Marc © WZL/Fraunhofer IPT

Seite 75

Criteria for the evaluation of FE software Program

ABAQUS

ANSYS/ LS-DYNA

AdvantEdge

DEFORM

COMSOL

Criteria Creation of geometries

Creation of geometries and import of CAD data

Import of CAD data

Creation of simple geometries and import of CAD data

Creation of simple geometries and import of CAD data

Creation of simple geometries and import of CAD data

Material catalogue

No, has to be defined

Yes, expandable

Yes, wide

Yes, new catalogue importable

yes

Element type

Every type

Every type

tetrahedron, rectangle

tetrahedron, rectangle

Every type

Time integration

Implicit / Explicit

Implicit / Explicit

Explicit

Implicit

Implicit

Remeshing routine

none

none

yes

yes

yes

use

general

general

Cutting process

Deforming process

general

Influence on simulation computation

High, by Python

Possible, by Fortran

no

High, by Fortran

High, by Matlab

parallelization

possible

possible

possible

possible

possible

Usage at the WZL

Eigenfrequency analysis, elast. Tool behavior, elasto-plastic component behavior

no

no

Cutting simulation

Thermo-elastic deformation

Source: SIMULIA, ANSYS, LSTC, TWS, SFTC, COMSOL © WZL/Fraunhofer IPT

Seite 76

Cutting process simulation Turning

Drilling

Milling

Calculation of the thermo-mechanical tool-load-collective for an ideal dimensioning of the tools‘ micro- and macrogeometry © WZL/Fraunhofer IPT

Seite 77

Simulation of the chip flow (turning) Chip breaker FN

Chip breaker RN Material: C45E+N Cutting material: HC P25 Insert: CNMG120408

Insert geometry:

0 0

S

r



6° -6 ° -6° 95° 90°

Cutting velocity.: vc = 300 m/min Feed: f = 0,1 mm Depth of cut: ap = 1 mm

Dry cutting

© WZL/Fraunhofer IPT

Seite 78

Segmented Chip Simulation reveals periodic sticking zone

 First Contact







Start of Shearing

Crack Initiation

Gliding







strain rate

75 62,5 50 37,5

25 12,5

Material Speed / m/min

90



End of Gliding New Segmentation

Start of Shearing

Crack initiation

0 © WZL/Fraunhofer IPT

Seite 79

Fc

Fc

1000

600 200

Ff

Fp

vc = 250 m/min

1400

Fp

Ff

vc = 350 m/min

constant: vc = 350 m/min; f = 0.1 mm

constant: vc = 350 m/min; ap = 3 mm

Fc 1400

Fc

1000 600 200

Fp

Ff

f = 0.1 mm

Ff Fp f = 0.2 mm

Fc 1000 600 200

Fc Ff

Fp

ap = 1 mm © WZL/Fraunhofer IPT

Fp

Ff

experiment simulation

Process forces Fi/ N

1800

experiment simulation

constant: f = 0,1 mm; ap = 3 mm

Process forces Fi/ N

1400

experiment simulation

Process forces Fi/ N

Verification of the mechanical load

Cutting tool material: Workpiece material: CL: Process:

HC-P25 C45E+N dry turning

ap = 3 mm Seite 80

FE simulation of turning considering coating TiN

Tsp

TiN

570

6 µm Calculated temperature at the chip bottom side TSp / °C

3 µm

6 µm

557

560 550 539

540

539

533 530 520 509

510

Al2O3

0 coating thickness

TiN 3 µm

TiN 6 µm

heat conductivity: HW: 100 W/(mK) TiN: 26,7 W/(mK) Al2O3: 7,5 W/(mK)

HW

TiN 6 µm

Al2O3 6 µm

heat capacity: HW: 3,5 J/(cm³K) TiN: 3,2 J/(cm³K) Al2O3: 3,5 J/(cm³K)

material: C45E+N HW: HW-K10/20 tensile strength: Rm = 610 N/mm² © WZL/Fraunhofer IPT

Seite 81

FE-Based Calibration process for the tool wear model Modeling

Verschleißmarkenbreite über die Schnittzeit 16MnCr5 (einsatzgehärtet), Stegbreite = 1 mm, cBN bestückte Einstechplatte der Sorte N151.2-600-50E-G Schnittgeschwindigkeit vc = 150, 200, 300 m/min und Vorschub f = 0,06 mm

Wear curve

Machining experiments 120

vc = 200 m/min

vc = 150 m/min

Verschleißmarkenbreite VB [µm]

Tool-wear VB

vc = 250 m/min 100

80

t = 10 min t = 6 min t = 4 min t = 1 min

60

40

20

0 0

5

10

15

20

25

Cutting time t

30

35

40

Schnittzeit t [min]

dW  σ n  v ch  C1  e dt

C ( 2 ) T

lg C1 lg {w /( n VS)}

Determination of the specific material parameters C1 and C2

dW/dt Regression analysis

FE-analysis  Temperature  Normal-

C2

tension  Sliding speed

1/T

© WZL/Fraunhofer IPT

Seite 82

Outline 1

Lecture organisation

2

Presentation of WZL

3

Lecture objectives

4

Modelling and simulation: Definition, motivation and integration

5

Lecture topics and fundamental knowledge

6

FE modelling for the forming process

7

FE modelling for the cutting process

8

FE model validation

9

Optimization integration in the FEM

© WZL/Fraunhofer IPT

Seite 83

Cutting force

Acceleration

Technical Sensors in Metal Cutting

Measuring platform

Rotating cutting force dynamometer

Acceleration sensor

Force measuring pin

vc

Process remarks

Load ring

Pyrometer

Source: Kistler Instrumente AG © WZL/Fraunhofer IPT

Seite 84

Temperature Sensor  Thermo-element

 Two color pyrometer

 Resistance thermometers

 Infrared camera

© WZL/Fraunhofer IPT

Seite 85

3D Coordinate Measuring

© WZL/Fraunhofer IPT

Seite 86

Features and Technical Data of the Test Bench  Shaft holder max. 32x32  Grooving / Parting Tool holders for orthogonal cutting (Inclination angle = 0°, tool edge angle = 0°)  Phantom v7.3 High speed video camera, LED Illumination vc= 20 m/min f = 0,3 mm

© WZL/Fraunhofer IPT

Workpiece holder

workpiece

vc

1 mm

Seite 87

Advanced Experimental Setup: Orthogonal Cut on Broaching Machine

tool tool holder

workpiece

High-Speed Filming

workpiece holder

HS camera

measurement platform

 High speed camera: – Type: Vision Research Phantom v7.3 – Frame rate: 6.688 fps by 800 x 600 pixel 500.000 fps by 32 x 16 pixel

tool

© WZL/Fraunhofer IPT

workpiece holder

workpiece

IR camera

High-Speed Thermography

 High speed external broaching machine: – Type: Forst RASX 8x2200x600 M/CNC – Max. force: 80 kN – Power: 40 kW – Max. cutting speed: 150 m/min – Tool fixed und workpiece moved – Optimal filming of the cutting zone

 High speed IR camera: – Type: FLIR SC7600 – Frame rate: 100 fps by 640 x 512 pixel 800 fps by 160 x 128 pixel – Measurement range: -20°C - 3000 °C (±1°C) Seite 88

Turning: Comparison of Simulation and Real Chip Flow CNMG120408 Chip breaker NF HC-P15 r = 95° n = -6° s = -6° C45E+N

ap = 1,9 mm f = 0,25 mm vc = 200 m/min dry

vf

© WZL/Fraunhofer IPT

vc Seite 89

FE simulation of face milling operation Experiment

.

Simulation

Full agreement © WZL/Fraunhofer IPT

Seite 90

FE computation of mechanical tool load and chip form in drilling

7% Deviation

400

2,0 1,0 0,0

300 200 100

Simulation

Simulation Simulation

3,0 Simulation

[N]

Experiment

[Nm]

Experiment Experiment

4% Deviation

Experiment

0 Torque Cutting speed: Feed: Drill diameter:

© WZL/Fraunhofer IPT

Feed force vc = 35 m/min f = 0.18 mm d = 8 mm

Workpiece: Cutting tool material: Cutting edge radius:

C45E+N HW-K20 rß = 60 µm Seite 91

FE computation of the cutting temperature in drilling

Temperature at the major cutting edge T [°C]

400 Experiment Simulation

d = 3 mm

300

200

100

0 1

3

8

10

diameter d [mm]

Cutting speed: Feed: Coolant: © WZL/Fraunhofer IPT

vc = 35 m/min f = 0,012 * d none

Workpiece: Cutting tool material: Cutting edge radius:

C45E+N HW-K20 rn = 4 µm Seite 92

High Speed Thermography During Chip Formation (vC = 150 m/min) h = 0.10 mm

h = 0.50 mm 600 400 °C

350

300

250 200 50 0

 Workpiece:

AISI 1045 normalized 3.5 x 50 x 200 mm © WZL/Fraunhofer IPT

 Tool:

Carbide, uncoated Sharp (rß  5 µm) Seite 93

Material and Friction Laws Validation: Chip Formation (Orthogonal Cut, vC = 150 m/min, AISI 1045) h = 0.5 mm

FE simulation

Experiment

h = 0.2 mm

FE simulation Experiment © WZL/Fraunhofer IPT

h = 0.4 mm

FE simulation

Experiment

h = 0.04 mm

FE simulation

Experiment

h = 0.3 mm

FE simulation

Experiment

h = 0.02 mm

FE simulation

Experiment Seite 94

Material and Friction Laws Validation: FE Cutting Simulation (vC = 150 m/min, h = 0.50 mm, DEFORM) Plastic strain

[-]

Effective stress [MPa]

© WZL/Fraunhofer IPT

Strain rate [1/s]

Temperature [ C]

Seite 95

Development of 3D FE computation model for macro twist drilling: d = 8 mm, homogeneous microstructure, Deform 3D Boundary conditions adjustment

Twist drill CAD model

 Twist drill: Rigid with mesh

RT100U_5510

d = 8 mm and rß = 30 µm  Workpiece: Visco-plastic

D x H = 12 x 4 mm with heat dissipation 100,000 3D-Tetrahedron  Contact: Coulomb friction

Twist drill

d = 8 mm rß = 0 µm

Gühring KG

law (µ = 0.30), heat transfer (Conduction & Convection) Cutting parameters definition  Workpiece material: 27R, 45R, 60R

 Tool material:

HW

 Cutting speed:

120 m/min

 Feed rate:

0.25 mm/rev

© WZL/Fraunhofer IPT

Workpiece

Constitutive material law (WZL) m     T  Tr   ε n   σ  A  B ε 1  C ln  1    ε 0    Tm  Tr     





Seite 96

FE model results: Chip formation, temperature, computation time: 1 day 45R, vc = 120 m/min, f = 0.25 mm, d = 8 mm, dry

© WZL/Fraunhofer IPT

Seite 97

FE-Simulation of the drill entrance: Computation time: 5 days 45R, vc = 120 m/min, f = 0.25 mm, d = 8 mm, dry

© WZL/Fraunhofer IPT

Seite 98

Check of the optimized FE model: Feed force and torque 45R, vc = 120 m/min, f = 0.25 mm, d = 8 mm, dry 1500

16

Feed force Fz / N

12

Feed force

1000

10

without entrance

750

8

with entrance 6

500

Torque Mz / Nm

14

1250

4 250

2

Torque

0

0

10

20

30

40

50

60

70

0 80

Drilling time t / ms © WZL/Fraunhofer IPT

Seite 99

FE model validation: Feed force and torque (deviation less than 15%) vc = 120 m/min, f = 0.25 mm, d = 8 mm, dry 7

kN6 Nm 5

Test 4

FE-Simulation

3 2 1 0

Feed force

Torque

27MnCr5 © WZL/Fraunhofer IPT

Feed force

Torque

C45E

Feed force

Torque

C60 Seite 100

Outline 1

Lecture organisation

2

Presentation of WZL

3

Lecture objectives

4

Modelling and simulation: Definition, motivation and integration

5

Lecture topics and fundamental knowledge

6

FE modelling for the forming process

7

FE modelling for the cutting process

8

FE model validation

9

Optimization integration in the FEM

© WZL/Fraunhofer IPT

Seite 101

What is the Optimization Problem? Minimize (or maximize) an objective „performance“ function:

taking into account the constraints:  (x1,x2,…,xn)

F(x1,x2,…,xn)

Gi(x1,x2,…,xn) = 0, i=1,2,…,p

Hj(x1,x2,…,xn) < 0, j=1,2,…,q

are the n system variables

 Gi(x1,x2,…,xn) are the p equality constraints  Hj(x1,x2,…,xn) are the q inequality constraints Source:Papalambros © WZL/Fraunhofer IPT

Seite 102

System Example: Cantilever Beam L Steel (E, ρ)

h b U(t), Mb(t), V(t)

h

Mathematical model:

FL3 U  3EI

 System variables:

FL3  bh 3 3E  12

© WZL/Fraunhofer IPT

F(t)

System

U(t)

U(t)

System

F(t)

F(t)

System

Mb(t)

h, b, L E, ρ

System

V(t)

F(t), U(t), Mb(t), V(t)

 System parameters: h, b, L  System constants:

4 F L3   E b h3   

E, ρ

F(t)

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Integration of the Optimization in the FEM Change physical problem

Physical problem

Improve mathematical model

Mathematical model

Numerical model Optimization

FEM

Does answer make sense?

No! Refine analysis Process improvement and optimization

Yes! © WZL/Fraunhofer IPT

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Thank you for your attention

© WZL/Fraunhofer IPT

Seite 105