Success with ModelSmart3D Pre-Engineering Software Corporation Written by: Robert A. Wolf III, P.E. Copyright 2001, Pre-Engineering Software Corporation,

Success with ModelSmart3D

Pre-Engineering Software Corporation

Written by: Robert A. Wolf III, P.E.

Copyright 2001, Pre-Engineering Software Corporation, All Rights Reserved

Show 3

Success with ModelSmart3D - Part VI Slide No. 2

Series Outline Show # 1

I. Possible benefitsII. Introduction to bridge

trussesIII. Modeling for structural

analysisShow # 2IV. Using ModelSmart3DV. Extra for ExpertsShow # 3VI. OptimizationVII. PrintingShow # 4VIII. Building Your ModelShow # 5IX. Final Project

Success with ModelSmart3D - Part VI Slide No. 3

VI. Optimization

1. Overall Geometry of the Structure2. Characteristics of the Individual

Elements.

Success with ModelSmart3D - Part VI Slide No. 4

VI. Optimizing - Geometry1. Geometry - Form and Height

Super Structure Overhead

Under Slung

Height

TaperNoTaper

Success with ModelSmart3D - Part VI Slide No. 5

VI. Optimizing - ElementsElement – Orientation, Material Grade and Cross Section

OrientationElement

Connection Details

Angle

Direction

Material Grade -Density Cross Section

Element Length

Success with ModelSmart3D - Part VI Slide No. 6

Our Example

We are designing a 12” span bridge that will be tested by a 20 pound weight hung from a 4”x2 3/4”x3/4” test block placed at the center of the span.

Success with ModelSmart3D - Part VI Slide No. 7

Optimizing Geometry - Truss Height

Success with ModelSmart3D - Part VI Slide No. 8

Delete Miscellaneous Bracing

Success with ModelSmart3D - Part VI Slide No. 9

Move Origin to Left Front Joint

Success with ModelSmart3D - Part VI Slide No. 10

Open the Joint Properties Dialog

Success with ModelSmart3D - Part VI Slide No. 11

Change Bridge Height

Success with ModelSmart3D - Part VI Slide No. 12

Re-analyze Model

Success with ModelSmart3D - Part VI Slide No. 13

Adjust Compression Member Length

Success with ModelSmart3D - Part VI Slide No. 14

Member Failure Modes

Tension Compression

Pulling Apart

BucklingCrushing

Success with ModelSmart3D - Part VI Slide No. 15

Finish New Bridge Geometry

Success with ModelSmart3D - Part VI Slide No. 16

Re-Analyze Model

Success with ModelSmart3D - Part VI Slide No. 17

Optimizing the Element - Material Grade

Voids and Wood Fiber

More Voids - Less Wood Fiber Lighter and WeakerSame Cross Sectional Area

End View of Balsa Wood Stick

Success with ModelSmart3D - Part VI Slide No. 18

Determining material grade

The Density Method 1. Number each balsa stick.2. Weigh each balsa stick – in grams. (Record the weight and size of each stick.)3. Calculate the density of each stick.4. Classify each stick by grade.5. Place a grade mark on each stick.

Success with ModelSmart3D - Part VI Slide No. 19

Density Method Example

1. Number the stick

2. Weigh the stick

From balance:

2.55 grams

Success with ModelSmart3D - Part VI Slide No. 20

Example Continued

3. Calculate the density (Wt/Vol.).

33

in 12

ft 1

1

in 5625.

33

33

ft 0003255.in 12

ft 1

1

in 5625.

Volume of the stick: 3in 5625.368

1

8

1V

Change units to ft3:

Success with ModelSmart3D - Part VI Slide No. 21

Example Continued

lbs 0056218.grams 453.59

lb 1

1

grams 55.2

Weight of the stick = 2.55 grams

Change units to pounds:

33

lbs/ft 2.17ft 0003255.

lbs 0056218.

V

WtDensity

Success with ModelSmart3D - Part VI Slide No. 22

4. Classify

MaterialGrade

ShapeSize

in x in

CantileverSpan(in.)

Test Weight(grams)

DeflectionThreshold

(in.)

Density(pcf)

BalsaD1 1/8 x 1/8 12 10 1.0 12

BalsaD1.1 1/8 x 1/8 12 10 .92 14BalsaD1.2 1/8 x 1/8 12 10 .83 16BalsaD2 1/8 x 1/8 12 10 .75 18

BalsaD2.1 1/8 x 1/8 12 10 .67 20BalsaD2.2 1/8 x 1/8 12 10 .58 22BalsaD3 1/8 x 1/8 12 10 .50 24

BalsaD13/16 x3/16

12 20 .625 12

BalsaD1.13/16 x3/16

12 20 .58 14

BalsaD1.23/16 x3/16 12 20 .54 16

BalsaD23/16 x3/16

12 20 .50 18

BalsaD2.13/16 x3/16

12 20 .46 20

BalsaD2.23/16 x3/16

12 20 .42 22

BalsaD33/16 x3/16

12 20 .375 24

___________________________________________________10-3

From Table pg 10-3

Grade = BalsaD1.2

5. Apply Grade Mark

Success with ModelSmart3D - Part VI Slide No. 23

Using Exact Density

Open the

“Edit Material”

Dialog.

Success with ModelSmart3D - Part VI Slide No. 24

Material Grade

Success with ModelSmart3D - Part VI Slide No. 25

Final Design!

Success with ModelSmart3D - Part VII Slide No. 26

VII. Printing

Success with ModelSmart3D - Part VII Slide No. 27

Move the XY GuidePlane

Success with ModelSmart3D - Part VII Slide No. 28

Show Tiles

Success with ModelSmart3D - Part VII Slide No. 29

Move Tiles

Success with ModelSmart3D - Part VII Slide No. 30

Print the Tiles

Success with ModelSmart3D - Part VII Slide No. 31

End Of Show 3