Computational and theoretical problems in modern rapid prototyping
Advertisement
This presentation is the property of its rightful owner.
1 / 40

Computational and Theoretical Problems in Modern Rapid Prototyping PowerPoint PPT Presentation

Computational and Theoretical Problems in Modern Rapid Prototyping. Mark R. Cutkosky Stanford Center for Design Research. http://cdr.stanford.edu/interface. Outline. Introduction to Layered Manufacturing Commercial and research processes Enabling factors (why now)

Download Presentation

Computational and Theoretical Problems in Modern Rapid Prototyping

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Computational and theoretical problems in modern rapid prototyping

Computational and Theoretical Problems in Modern Rapid Prototyping

Mark R. Cutkosky

Stanford Center for Design Research

http://cdr.stanford.edu/interface


Outline

Outline

  • Introduction to Layered Manufacturing

    • Commercial and research processes

    • Enabling factors (why now)

  • Capabilities and opportunities

    • (Almost) arbitrary geometry

    • Functionally graded materials

    • Integrated assemblies, “smart parts”

  • Computational challenges

    • Huge design space

    • Analysis

    • Process planning and control

  • Summary

NAS Math. Modeling Forum 5/10/99 -mrc


Traditional manufacturing a sequential process of shaping and assembly

Traditional manufacturing:a sequential process of shaping and assembly

NAS Math. Modeling Forum 5/10/99 -mrc


Layered manufacturing commercial example

Layered Manufacturing: commercial example

UV curable

liquid

Laser

elevator

Formed

object

Photolithography process

schematic

Sample prototype (ME210 power mirror for UT Auto)

http://me210.stanford.edu

NAS Math. Modeling Forum 5/10/99 -mrc


Almost arbitrary 3d geometries

Almost arbitrary 3D Geometries

Tilted frames (RPL)

Loop Tile -- dense tiling of 3D space. (Carlo Sequin, U.C.B.)

Minimum toroidal saddle surface

(C. Sequin)

NAS Math. Modeling Forum 5/10/99 -mrc


From rp and cnc to

Shape Deposition Manufacturing ( SDM)

From RP and CNC to . . .

RP

CNC

1970

1990

2000

NAS Math. Modeling Forum 5/10/99 -mrc


Shape deposition manufacturing cmu su

Shape Deposition Manufacturing (CMU/SU)

Embedded Component

Part

Support

Deposit (part)

Shape

Shape

Deposit (support)

Embed

NAS Math. Modeling Forum 5/10/99 -mrc


Sdm 1 injection mold tooling su rpl

SDM#1: Injection mold tooling (SU RPL)

NAS Math. Modeling Forum 5/10/99 -mrc


Sdm 2 frogman cmu

SDM #2: Frogman (CMU)

  • Example of polymer component with embedded electronics

NAS Math. Modeling Forum 5/10/99 -mrc


Sdm 3 ceramic parts rpl

Alumina vane

SDM #3: Ceramic parts (RPL)

Silicon nitride pitch shaft

Alumina turbine wheels

NAS Math. Modeling Forum 5/10/99 -mrc


Sdm for integrated assemblies

Shaft coupling

Shaft

Motor

Leg links

SDM for integrated assemblies

Motivation: Building smallrobots with prefabricatedcomponents is difficult...and results are not robust.

NAS Math. Modeling Forum 5/10/99 -mrc


Sdm 4 robot leg with embedded components

SDM #4: Robot leg with embedded components

(http:cdr.stanford.edu/biomimetics)

Steel leaf spring

Designer composes the design from library of primitives, including embedded components

Piston

Part Primitive

Outlet for valve

Valve Primitive

Circuit Primitive

Inlet port primitive

NAS Math. Modeling Forum 5/10/99 -mrc


Nas 5 99

Robot Leg design (cont’d.)

Steel leaf-spring

Internal components are modeled in the 3D CAD environment.

Piston

Sensor and circuit

Spacer

Valves

Components are prepared with spacers, etc. to assure accurate placement.

NAS Math. Modeling Forum 5/10/99 -mrc


Nas 5 99

Robot Leg: compacts

The output of the software is a sequence of 3D shapes and toolpaths.

Embedded components

Part

Support

NAS Math. Modeling Forum 5/10/99 -mrc


Robot leg embedded parts

Robot Leg: embedded parts

Steel leaf-spring

Piston

Sensor and circuit

Valves

A snapshot just after valves and pistons were inserted.

NAS Math. Modeling Forum 5/10/99 -mrc


Nas 5 99

Robot Leg: completed

Finished parts ready for testing

NAS Math. Modeling Forum 5/10/99 -mrc


Layered manufacturing is it a new manufacturing paradigm

Layered Manufacturing: is it a new manufacturing paradigm?

Laminated manufacturing

(1892-1940s)

Photo-sculpture

studio (1860)

Laser-based photolithography (1977)

[Source:Beaman 1997]

NAS Math. Modeling Forum 5/10/99 -mrc


A process enabled by computing

A process enabled by computing...

3D solid model

slicing

trajectory planning

material addition process

data exchange format

motion control trajectories

CAD

process planner

fabrication machine

NAS Math. Modeling Forum 5/10/99 -mrc


Summary of layered manufacturing processes

Commercial

Photolithography

Fused deposition

Laser sintering

Laminated paper

Research

Selective laser sintering (UT Austin)

3D printing (MIT)

Shape deposition manufacturing (CMU/Stanford)

Engineering materials (metals,

ceramics, strong polymers)

Graded materials

Embedded components

Not quite direct from CAD model...

“Look and feel” prototype

Complex 3D shapes

direct from CAD model

Summary of layered manufacturing processes

NAS Math. Modeling Forum 5/10/99 -mrc


Layered manufacturing results in a huge space of possible designs

Layered manufacturing results in a hugespace of possible designs:

  • Ability to create arbitrary 3D structures with internal voids

  • Ability to vary material composition throughout the structure

  • Ability to embed components such as sensors, microprocessors, structural elements.

What kind of design environment will help designers to understand and exploit the potential of layered manufacturing?

NAS Math. Modeling Forum 5/10/99 -mrc


Ability to create arbitrary 3d structures with internal voids homogeneous materials

Ability to create arbitrary 3D structures with internal voids (homogeneous materials)

W

Shape optimization example:

Find the minimum-weight shelf structure, bounded by box B,

that supports load W without failing.

B

Space within B is divided into N cells, each of which can be filled or empty. Number of unique designs  2N

NAS Math. Modeling Forum 5/10/99 -mrc

Rapid Prototyping Workshop 5/99 -mrc


Ability to vary material composition

Ability to vary material composition

Deposition heads can be controlled to deposit varying amounts of each material* as the part is built. Total material composition varies throughout the part.

deposition

heads

Support structure

Volume fractions always add to unity*

*void, or empty space, is treated as a special case of material

NAS Math. Modeling Forum 5/10/99 -mrc


Material composition product space

Material composition: product space

m = number of materials (including void)

vi= volume fraction of each material

r = deposition mixture resolution

Product Space:

Example: urethane, glass fibers, teflon, and void, controlled to a resolution of 10% volume fraction  286 unique mixtures possible.

NAS Math. Modeling Forum 5/10/99 -mrc


Design space with arbitrary geometry and heterogeneous materials e 3 t m

Design space with arbitrary geometry and heterogeneous materials (E3 Tm)

W

Shape + material optimization:

Assume m possible materials,

(including void) with a mixture resolution of r.

B

Space within B is discretized into N cells, each of which

can be filled with a unique mixture of materials.

Number of unique designs 

N

Example: 101010 cells, 4 materials, 10% mixture resolution

 2861000designs!

NAS Math. Modeling Forum 5/10/99 -mrc

Rapid Prototyping Workshop 5/99 -mrc


Toward a design environment for layered manufacturing

Toward a design environment for layered manufacturing

  • The design space is huge.

  • But there are significant constraints associated with the manufacturing processes.

  • Therefore, provide an environment that combines manufacturing analysis, design rules, and design libraries to help designers explore the full potential of layered manufacturing.

NAS Math. Modeling Forum 5/10/99 -mrc


Computational issues 1 process planning

Computational issues #1:Process Planning

Decompose

Input

Deposit

Machine

Decompose

Deposit

Machine

  • Process constraints

  • Manufacturability

  • Support structures

  • Deposition method

  • Deposition parameters

  • Path planning

  • Machining method

  • Tool selection

  • Machining parameters

  • Path planning

(source:J.S. Kao SU RPL)

NAS Math. Modeling Forum 5/10/99 -mrc


Decomposition into compacts and layers

Decomposition into ‘compacts” and layers

Complete

Part

Compacts

Layers

Tool Path

NAS Math. Modeling Forum 5/10/99 -mrc


Nas 5 99

Decomposition based on process sequence

(5)

(6)

(7)

(8)

NAS Math. Modeling Forum 5/10/99 -mrc


Definitions compact merz et al 94

Definitions: Compact[Merz et al 94]

  • 3-D volume with no overhanging features

  • Rays in growth direction enter only once

  • Compacts correspond to SDM cycles

z2

z1

Build Axis

(a) no good

(b) OK

(c) OK

NAS Math. Modeling Forum 5/10/99 -mrc


Decomposition algorithms

Decomposition algorithms

Locate silhouette edges, split surfaces

Merge compacts

Extrude concave loops

(source:J.S. Kao SU RPL)

NAS Math. Modeling Forum 5/10/99 -mrc


Nas 5 99

Deposition Process Planning (RPL)

  • Thermal Stresses Develop due to:

    • Temperature gradients

    • Differences in expansion coefficient

  • Thermal Stresses Cause:

    • Part inaccuracy

    • Delamination

  • Solutions

    • Develop optimal deposition path and process parameters to minimize thermal stresses

    • Tailor alloy to maintain desirable properties while minimize thermal expansion coefficient

NAS Math. Modeling Forum 5/10/99 -mrc


Problems with automated process planning

Problems with automated process planning

  • finite thickness of support material

  • finish on unmachined surfaces

  • warping and internal stresses

  • decomposition depends on geometry,not on intended function

NAS Math. Modeling Forum 5/10/99 -mrc


Design by composition m binnard

Design by Composition(M. Binnard)

Users build designs by combining primitives with Boolean operations

  • Primitives have high-level manufacturing plans

  • Embed components and shapes as needed

Primitives

merged by designer

Manufacturing plans

merged by algorithm

NAS Math. Modeling Forum 5/10/99 -mrc


Toward a mechanical mosis

a)

(top view)

b)

(side view)

d

d

d(a1,a2)

d(a1,a2)

l

2l

Dd

Minimum gap/rib thickness

Generalized 3D gap/rib

e)

(side view)

2l

l

d(m1,m2,m3)

d(m1,m2,m3,a1,a2)

Wc/l >= 2

m1

m2

m3

m1

m2

m3

Minimum feature thickness

Toward a mechanical MOSIS?

SFF/SDM

VLSI

Boxes, Circles,

Polygons and Wires

Decomposed Features

SFF/SDM Design Rules

Mead-Conway Design Rules

NAS Math. Modeling Forum 5/10/99 -mrc


Primitive compact set precedence graph

Primitive = Compact Set + Precedence Graph

Primitive

Compact set

Compact precedence graph

  • Set of valid compacts

  • No intersections

  • Fills the primitive’s projected volume

  • Acyclic directed graph

  • Link for every non-vertical surface


Merging algorithm example

A

B

Merging Algorithm Example

+

=

A

B

C=A È B

intersection compacts

non-intersecting compacts

NAS Math. Modeling Forum 5/10/99 -mrc


Combining composition and decomposition

Combining composition and decomposition

CAD

MODEL

re-analysis

(if needed)

DESIGN

DECOMPOSITION

DESIGN BY

COMPOSITION

LIBRARY:

Decomposed Designs &

primitives

COMPACT

SET

CPG

SEQUENCE

&

TOOL PATH PLANNING

NAS Math. Modeling Forum 5/10/99 -mrc


A need for integrated mechanical thermal and electrical analysis

A need for integrated mechanical, thermal and electrical analysis

VuMan (CMU) mechanical, thermal analysis

NAS Math. Modeling Forum 5/10/99 -mrc


Summary

Summary

Emerging layered manufacturing processes such as SDM:

  • are made feasible by recent advances in desktop computing and solids modeling

  • afford a huge design space (E3 Tm)

  • provide a rich area for geometric reasoning and process planning

  • present formidable challenges in analysis, process planning and control to achieve consistent, high-quality parts

NAS Math. Modeling Forum 5/10/99 -mrc


Acknowledgements

Acknowledgements

Thanks to the members of the Center for Design Researchand the Stanford Rapid Prototyping Lab for

their work in generating the results and ideas described in this presentation.

This work has been supported by the

National Science Foundation (MIP-9617994)

and by the Office of Naval Research (N00014-98-1-0669)

NAS Math. Modeling Forum 5/10/99 -mrc


  • Login