OMIS 661 Presentation – Intelligent System Case Caterpillar uses optimization to reduce structural mass while improving structural strength Presenters

OMIS 661 Presentation – Intelligent System Case

Caterpillar uses optimization to reduce structural mass while improving structural strength

Presenters – Celeste Latham and John Kearsing

Agenda

•Concept Introduction

•Structural optimization

• Terminology

• Optimization process

• Caterpillar’s Virtual Product Development position

• Optistruct demo

• CAT optimization

OMIS 661 Presentation – Intelligent System Case Agenda

Structural optimization is an automated technique that derives the optimal design of a structure given design criteria.

Structural optimization has the potential to:.

–Significantly reduce material costs by optimizing structural designs with respect to specified goals

–Accelerate product development through the elimination of manual design and analysis iterations

–Improve product quality and reliability by promoting early and frequent analysis of structural strength and life

OMIS 661 Presentation – Intelligent System Case Concept Introduction

Material optimization Terminology

Topology optimization Optimal material layout in a given package space

Shape optimization Optimal Shape of a given geometric feature

Size optimizationParametric optimization

Ex. Gage thickness, Beam sections etc



Topology Optimization

Size & ShapeOptimization

Final Design

Design Interpretation

Different Iterations

Intelligent SystemIntelligent System

engineerengineer engineer

Structural Optimization Process

A Fortune 100 company, Caterpillar is the world's leading manufacturer of construction and mining equipment, diesel and natural gas engines and industrial gas turbines. The company is a technology leader in construction, transportation, mining, forestry, energy, logistics, electronics, financing and electric power generation.

Key company facts :

• ~$23,000,000,000 company

• ~69,000 employees

• Averages 500 patents per year

• Over 1000 PhDs/CEO PhD

OMIS 661 Presentation – Intelligent System Case CAT & VPD


• Every component on a CAT tractor is modeled in a 3D modeling system prior to creation – Millions of models. This has set the stage for Caterpillar’s Virtual Product Development Strategy.


• More time spent in the early stages of virtual product development to better reduce time spent maintaining the product in the later stages.

VIRTUAL PRODUCT DEVELOPMENT

Product design/refinement

Concept Detailed Design Testing

Accelerated Knowledge

FreedomProduct definition

`

Produ

ct Kno

wledge




• Structural Optimization is one focus of VPD• Caterpillar is using Optistruct, a product developed by Altair Engineering, to help achieve

the goals of VPD


Optistruct DemoOptistruct Demo

Courtesy TECOSIM GmbH, RuesselsheimCourtesy TECOSIM GmbH, Ruesselsheim

▲ Original bracket failed▲ Reduce stress in bracket

Topology OptimizationRadiator Bracket – Design Package Space

Topology OptimizationRadiator Bracket – Optimization Results


Topology OptimizationRadiator Bracket – Geometry Extraction/Design Interpretation

VOLUME = 0.3Density Threshold = 0.6


Topology OptimizationRadiator Bracket – CAD Detailing of Concept Design


Design from Optistruct Final Interpreted Design

Topology OptimizationRadiator Bracket – Final Detailed Design


Topology OptimizationRadiator Bracket – Design Validation


OriginalDesign

OptimizedDesign

Max. v. Mises Stress Max. Displ. Mass

Optimization of SUV Chassis Frame

Optimization Objectives:

Re-design the Chassis Frame Minimize the Mass Maintain the same structural stiffness


Identify the maximum design space

Topology Optimization


Optimal Placement of Material

Topology Optimization Result


First Concept Design

Evaluation of topology optimization result

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Optimization of SUV Chassis FrameAnalysis of First Concept Design

Cross-member

Open C-Section

Closed C-Section

Optimization of SUV Chassis FrameTopology Optimization of First Concept Design

Topology optimization on shell structure:

Re-define Material Placement

Cross-member

Closed C-Section

Open C-Section

Optimization of SUV Chassis FrameSecond Concept Design

-12%300

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Lighter Structure

Optimization of SUV Chassis FrameOptimal Design

-23%300

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Design tuning using shape and size optimization

Optimization of SUV Chassis FrameDesigns Comparison

Baseline Frame:

Ladder Frame Design – 226 kg

Optimized Frame:

Lightweight Concept – 174 kg (-23%)

● Including Torsion Bar & Trans C/M

● Mass: 498(lbs) [226(kg)]**

Target Weight Reduction 125lbs (25%)

● Performance Targets:– Twist: 18.7 Hz

– Vertical Bend: 27.1 Hz

– Lateral Bend: 29.0 Hz

– Bending Stiffness: 3278 N/mm

– Torsion Stiffness: 121 kNm/rad** Includes mass of welds (3kgs)

Topology Driven Vehicle Concepts Topology Driven Vehicle Concepts

● Lightweight SUV Frame Concept

– Baseline frame used for stiffness and modal targets


Define all available package space, Loading, and BC’s

Concept Development Process

Final Concept

Interpret into first concept design

Topology Optimization for gross concept features

Topology optimization for concept refinement

Interpret concept for final optimization and design details


● Final Concept Design– Primary Hydroformed Sections– Mid-Rail “C” Section– Welded Body Mount Brackets– 23% lower mass– 25% fewer parts– 50% less weld length– Cost penalty:

• $0.25 cost per lb saved

● Performance Results:– Twist: 25.0 Hz (+34%)– Vertical Bend: 27.8 Hz

(+2.5%)– Lateral Bend: 26.4 Hz (-9%)– Bending Stiffness: 3278 N/mm (0%)– Torsion Stiffness: 159 kNm/rad (+31%)

OMIS 661 Presentation – Intelligent System Case CAT Optimization

D8 Trunnion optimization


Fabricated Version: Mass=44.1 Kg

Original Fabricated Trunnion Design – 2 pieces


Design Objective

Design Constraints

Minimized Weight

Max Principle Stress (Yellow Part) < 372 Mpa

Von Mises Stress (Yellow Part) < 785 Mpa

Design Variables-Five•Inside pocket•Neck Radius•Neck Transition•Bolt Plate Thickness•TRF Inserted Flange Thickness


Final Design

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Current Optimized

weight

weight

Weight(kg) % ReductionCURRENT

FABICATION DESIGN 44.1

OPTIMIZED DESIGN 26.6 39.70%

Weight Results


Requirement: Max Principle Stress < 372 MPa Result: 187.9 MPa

Requirement: Von Mises Stress < 785 MpaResult: 757.3 MPa

Max. Load

Stress Results


Financial Results

• 40 % weight reduction from current production design

• $136 cost savings per a part

• 3260 parts are expected

• $443,360 annual cost savings


Future Uses

•Expand the optimization process other product lines

•Gain an estimated savings of $2 million in 2005


Questions?

Documents

OMIS 661 Presentation – Intelligent System Case Caterpillar uses optimization to reduce structural mass while improving structural strength Presenters