1. Mass Property Analysis
Introduction to Engineering Design
Unit 3 – Lesson 3.3 – Structural Analysis
Physical Property Analysis
Introduction to Engineering Design
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Copyright 2006

2. Mass Property Analysis
Introduction to Engineering Design
Unit 3 – Lesson 3.3 – Structural Analysis
Physical Properties
A physical property is a property that can be observed or measured without changing the identity of the matter.
Examples of Physical Properties:
Volume Density Color
Surface Area Centroid Moment of Inertia
Mass Odor Temperature
Weight Viscosity Electric Charge
Boiling Point Melting Point Attraction to magnets
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3. Physical Property Analysis
Mass Property Analysis
Introduction to Engineering Design
Unit 3 – Lesson 3.3 – Structural Analysis
Physical Property Analysis
The size, volume, surface area, and other properties associated with a solid model are often part of the design constraints or solution criteria.
The following are physical properties presented in typical solid modeling programs:
Volume Density Mass
Surface Area Center of Gravity Moment of Inertia
Product of Inertia Radii of Gyration Principal Axes
Principal Moments Length
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4. Mass Property Analysis
Introduction to Engineering Design
Unit 3 – Lesson 3.3 – Structural Analysis
Physical Properties
We have already investigated density, volume, and mass/ weight
Another important physical property is Surface Area
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5. Mass Property Analysis
Introduction to Engineering Design
Unit 3 – Lesson 3.3 – Structural Analysis
Surface Area
Surface area is the area of the
exterior surface of an object.
Surface area is important when determining coatings and heat transfer of a part.
Area A = 3 in. x 4 in. = 12 in.2
Area B = 4 in. x 8 in. = 32 in.2
Area C = 3 in. x 8 in. = 24 in.2
Area D = 4 in. x 8 in. = 32 in.2
Area E = 3 in. x 8 in. = 24 in.2
Area F = 3 in. x 4 in. = 12 in.2 B C D E F A
If you consider the flat pattern of the rectangular solid, you can imagine all six sides of the solid. To find the surface area, sum the area of all exterior surfaces of the object.
Surface Area = 136 in.2
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6. Mass Property Analysis
Introduction to Engineering Design
Unit 3 – Lesson 3.3 – Structural Analysis
Surface Area
Another way to represent the formula for surface area of a rectangular prism is given on the formula sheet
Project Lead The Way®
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7. Mass Property Analysis
Introduction to Engineering Design
Unit 3 – Lesson 3.3 – Structural Analysis
Surface Area
Surface Area = 2 [(8 in.)(4 in.) + (8 in.)(3 in.) + (4 in.)(3 in.)]
= 136 in.2
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8. Mass Property Analysis
Introduction to Engineering Design
Unit 3 – Lesson 3.3 – Structural Analysis
Formula Sheet
The formula sheet provides formulas for the volume and surface area of many solid forms
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9. Additional Physical Properties
Mass Property Analysis
Introduction to Engineering Design
Unit 3 – Lesson 3.3 – Structural Analysis
Additional Physical Properties
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Copyright 2006

10. Mass Property Analysis
Introduction to Engineering Design
Unit 3 – Lesson 3.3 – Structural Analysis
Center of Gravity
A 3D point where the total weight of the body may be considered to be concentrated.
The average location of an object.
If an object rotates when thrown it rotates about its center of gravity.
An object can be balance on a sharp point placed directly beneath its center of gravity
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11. Mass Property Analysis
Introduction to Engineering Design
Unit 3 – Lesson 3.3 – Structural Analysis
Centroid
A 3D point defining the
geometric center of a solid.
Do not confuse centroid with the center of gravity.
The two only exist at the same 3D point when the part has uniform geometry and density.
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12. Mass Property Analysis
Principal Axes
Mass Property Analysis
Introduction to Engineering Design
Unit 3 – Lesson 3.3 – Structural Analysis
The lines of intersection
created from three mutually
perpendicular planes, with the three planes’ point of intersection at the centroid of the part.
The X, Y, and Z axes show the principal axes of the ellipsoid.
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13. Physical Properties and 3D Solid Modeling
Mass Property Analysis
Introduction to Engineering Design
Unit 3 – Lesson 3.3 – Structural Analysis
Physical Properties and 3D Solid Modeling
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14. Physical Properties and 3D Solid Modeling
Mass Property Analysis
Introduction to Engineering Design
Unit 3 – Lesson 3.3 – Structural Analysis
Physical Properties and 3D Solid Modeling
3D solid modeling software can display physical properties of modeled objects.
In Browser right click on part name
Choose iProperties
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15. Mass Property Analysis
Introduction to Engineering Design
Unit 3 – Lesson 3.3 – Structural Analysis
Physical Properties
3D solid modeling software can display physical properties of modeled objects
In Browser right click on part name
Choose iProperties
Choose Physical tab
Choose appropriate material
Depress Update button
Physical properties are displayed
The physical property values will be used to estimate material quantity needed for production and finishing and for estimating packaging and shipping costs.
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Copyright 2006

16. Mass Property Analysis
Introduction to Engineering Design
Unit 3 – Lesson 3.3 – Structural Analysis
Sources
Brodinski, K. G. (1989). Engineering materials properties and selection. Prentice Hall, Inc.: Englewood Cliffs, NJ.
Budinski, K. G. (1992). Engineering materials (4th Ed.). Prentice Hall, Inc.: Englewood Cliffs, NJ.
Gere, J. M., & Timoshenko, S. P. (1997). Mechanics of materials. PWS Publishing Company: Boston.
Lockhart, S. D., & Johnson, C. M. (1999). Engineering design communication: Conveying design through graphics (Preliminary Ed.). Addison Wesley Longman, Inc.: Reading, MA.
Madsen, D. A., Shumaker, T. M., Turpin, J. L., & Stark, C. (1994). Engineering design and drawing (2nd Ed.). Delmar Publishers Inc.: Albany.
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