alcoa imr final

8/3/2019 Alcoa Imr Final

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Alcoa Lightweight Multi-material Structure Design

Research Proposal

Courtesy of ATZ Autotechnology July 2008


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Lightweight Structures and Multi-material Assembly

In order to achieve optimum strength to weight ratio, many assembliesneed to be multi-material

Material choices involve tradeoff decisions between density, strength,ductility, stiffness, etc.

The optimum way to design lightweight structures is to apply the right materialfor the function it is required to perform.

The assembly and joining of multi-material assembly requires novelmethods

Typical welding processes requires similar materials at the joint. Corrosiondue to electrochemical reaction is also a big issue with dissimilar metal

joining.

Traditional threaded fasteners or adhesives are too costly for mass produced

parts. The alternative to welded joints is novel mechanical fastening but results in

increasing number of joints.

Courtesy of SLCProject


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Assembly Based Research


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Background: Aircraft wheel assemblies have complexgeometries, load paths, and failure criteria. If most of

the design can be determined from simulation, theamount of changes during testing will be small.


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Research Approach

ImprovedConformal Joints

WIB DemonstrationPrototype

Application toStudent Projects

Optimized VehicleStructure

Novel FasteningSolutions


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Multiple graduated

channels to optimize jointstrength

Key variables Channel width

Depth

Edge fillet radius

Conformal Joints Improved Design

Multi-Directional Profile

Curved Profile

Standard Profile


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Axial Joint Prototype

Material combination Steel Aluminum

Magnesium

Composites


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Body-in-White Prototype

Focus on creative innovative solutions to common automotivecomponents.

Applicable to current vehicle platforms and can act as a intermediateterm solutions. Focus will be on cost effectiveness andmanufacturability as well as performance.

Next 1.5 years will be focused on creating and demonstrating

Constraint Design and Anal sis of Fastener Location and Orientation


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Constraint Design and Analysis of Fastener Location and Orientationin Mechanical Assembly (contd)

Leonard Rusli, Anthony Luscher

Where should I place my fasteners?

A optimization routine searches through the design spaceof constraint location, orientation, and number ofconstraints

Assembly performance is found to be optimum when thesnap-fits are located radially symmetric.

Non-symmetrical location of snap-fits induces a weaklyconstrained motion

Assembly is found to be ~40% weaker when constraintsare not symmetrically located in this case study.

Should we add more fasteners? As snap-fits are added, while the assembly performance increased,

redundancy increases at the same rate.

Redundancy is undesirable because of locked in stresses andindeterminate location

Beyond certain number of fastener, a point of diminishing return canbe identified:

SPRAY&HOUSING&CASE&STUDY

Project outcome: Created a design tool algorithm toanalyze assembly performance and optimize fastenerplacement, orientation, and addition/reduction.

O


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Attachment strategy for DOFRemoval

Many current automotive chassis arecomposed of sheet metal based on theunibody design.

Rather than designing a one-to-onereplacement the current design intolightweight material, the multi-materialdesign must challenge the currentassumptions of how a car chassis.

An example of this is the space-framedesign in Audi A8.

Att h t t t f DOF


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Attachment strategy for DOFRemoval

Shapes should be optimized according tocurrently affordable and reliablemanufacturing processes (ex: extrusions,continuous compression molding)

Courtesy of Cutting Dynamics, Inc.


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Lap Joint


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Joint Design and Optimization

With EMF conformal joint technology, innovative joints can bedeveloped to reduce weight of individual parts, number ofcomponents, fasteners, welding processes, and assembly time.

The example below show the elimination of bumper stay or crushcan flange welding and fastening to the bumper beam

St d t P j t & C i l


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Student Projects & CurriculumIntegration

P t ti l A li ti i Li ht i ht


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Number of fasteners = increas ed cost

Optimization of number of fasteners

Redundant design leads to locked in stresses

Reduction of redundan t fastenersOptimization of re dundant DOF re moval (fastener loca tion and orientation)

Conformal joints r ely heav ily on mating surface or ientation

Optimization of part shape to maximize DOF removal

Potential Applications in LightweightAssembly Design


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OBJECTIVE: Develop a Practical Design Knowledgefor novel multi-material structural design inAutomotive and Transportation Structures


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Deliverables

Deliverables:

BIW Demonstrationprototype

Multi-materialDesign catalog &know-how

Student projects(ME 581, SAEBaja, Formula

SAE local

1 Attachment strategy for DOF


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1. Attachment strategy for DOFRemoval

Optimization of number of discretefasteners

Incremental increase of cost for self-piercing

rivets is higher compared to spot-weld


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Joint Design and Optimization

Development of innovative joints andtaxonomy of multi-material joint design forvarious geometrical requirement

Sheet to extrusion, Sheet to sheet,

Extrusion to extrusion nodal joint

Material coating to prevent corossion

Development of design guideline foroptimization of joint design via virtualsimulation or empirical method

Investigation of usage of structural


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Sheet to sheet EMF Lap Joint

Before EMF Stamping

After EMF Stamping


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Sheet to sheet EMF Hem Joint

Before EMF Stamping

After EMF Stamping


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US Patent 7263757 and 6927370


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US Patent 7290318


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US Patent 2009/0272166 A1

E i E i J i


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Extrusion to Extrusion Joint

3 Experimental validation and


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3. Experimental validation andtesting

Fabrication of a demonstration prototypeassembly or sub-assembly

Static and fatigue testing of joints against

micro-creep.


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Oth A li ti f EMF A bl


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Other Applications of EMF Assembl

Courtesy of PST Productshttp://www.english.pstproducts.com/applications.htm

Oth A li ti f EMF A bl


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Other Applications of EMF Assembl



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