Materials Selection with Ashby Charts - Homework Assignment Solutions

Oct 29, 2026

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Answers and explanations for a materials selection homework using Ashby charts, addressing how chart scale and property placement affect interpretation. The solutions compare a logarithmic vs linear y-axis and discuss why ceramics and metals occupy the upper right quadrant via density, atomic structure, and bonding strength. They also explain foam density using the air component in hybrid foam structures. Additional sections evaluate design needs across different products using Young’s modulus, yield strength, fracture toughness, density, and price, with examples for bicycles and plates.

LanguageEnglish

CategoryExam

FormatPDF

Pages14

Reading Time35 min

AccessFree to download

Homework Questions

Property chart interpretation

Ranking materials for selection

Product-focused material regions

Bicycles: child vs racing bikes

Plates: disposable vs fine china

Materials Selection with Ashby Charts Homework Assignment Solutions Kaitlin Tyler and Claes Fredriksson ©2022 ANSYS, Inc. 1. Take a look at the two property bar charts below. What is the difference between them? Is one easier to read? Why or why not? Answer: Chart A uses Logarithmic scale for the Y-axis, while Chart B uses a linear scale. Chart A is significantly easier to read because of this, particularly for lower values of Yield Strength, such as for polymers and foams ©2022 ANSYS, Inc. 2 . Why are ceramics and metals in the upper right quadrant of this chart? Answer: Metals and ceramics have high density due to two factors: the atoms that make up the material generally have higher atomic mass and the arrangement of the atoms is highly ordered (or crystalline), which packs more closely. The bonds found in metallic and ceramic materials (metallic and covalent bonds) are very strong, which leads to a high Young’s Modulus ©2022 ANSYS, Inc. 3. Two materials are highlighted on this chart-a Flexible Polymer Foam and Polyurethane. Why is the flexible polymer foam less dense than the bulk matrix material, polyurethane? Answer: Foams are a hybrid material, meaning they are made of two or more components. Generally, the second component in foams is air. Air is significantly less dense than solid material, so the hybrid air/polyurethane foam is lighter than solid polyurethane. ©2022 ANSYS, Inc. 4. In the course, we discussed ranking materials for selection based on the design needs of the product. For bar charts, we are focusing on maximizing or minimizing our single material property. For bubble charts, we are focusing on different quadrants of the chart. For the set of products listed below, identify the area within each provided chart where we should focus our selection efforts. Do the areas of focus change across the set of products? Why or why not? Three charts were provided, with a total of five material properties to focus on: 1. Young’s Modulus (Stiffness) 2. Yield Strength (Strength) 3. Fracture Toughness (Resistance to breaking) 4. Density (Weight) 5. Price Looking at the list of properties we have data for in our property charts, we can determine if we want a high value, a low value, a moderate value, or if we have no preference. ©2022 ANSYS, Inc. (a) Bicycles: a child’s bike vs. a competitive racing bike Below are the values for each property for both a child’s bike and a racing bike. Then we can identify the portions of the relevant charts where these values might lie. | Property | Child’s Bike | Racing Bike | | --- | --- | --- | | Young’s Modulus (Stiffness) | High | High | | Yield Strength
(Strength) | High | High | | Fracture Toughness (Resistance to breaking) | High | High | | Density
(Weight) | -- | Low | | Price | Low | -- | ©2022 ANSYS, Inc. (a) Bicycles: a child’s bike vs. a competitive racing bike | Property | Child’s Bike | Racing Bike | | --- | --- | --- | | Young’s Modulus (Stiffness) | High | High | | Yield Strength (Strength) | High | High | | Fracture Toughness (Resistance to breaking) | High | High | | Density
(Weight) | -- | Low | | Price | Low | -- | Both bikes need high stiffness and strength to avoid bending in the frame and to be able to support the rider. That means both bikes need materials in the upper righthand quadrant, where metals, ceramics, and composites are found. ©2022 ANSYS, Inc. (a) Bicycles: a child’s bike vs. a competitive racing bike | Property | Child’s Bike | Racing Bike | | --- | --- | --- | | Young’s Modulus (Stiffness) | High | High | | Yield Strength (Strength) | High | High | | Fracture Toughness (Resistance to breaking) | High | High | | Density
(Weight) | -- | Low | | Price | Low | -- | Both bikes need a high fracture toughness to avoid breaking during use. Once again, ceramics, metals, and composites fall into the category with high fracture toughness. ©2022 ANSYS, Inc. (a) Bicycles: a ch

FAQs

How does the difference in Y-axis scaling affect readability between Chart A and Chart B?

Chart A uses a logarithmic Y-axis, while Chart B uses a linear scale. Chart A is significantly easier to read, especially for lower yield strength values.

Why do ceramics and metals fall in the upper right quadrant of the Ashby chart?

They have high density due to higher atomic mass and highly ordered (crystalline) atomic packing. Strong metallic or covalent bonds lead to a high Young’s Modulus.

Why is flexible polymer foam less dense than polyurethane in the chart?

Foams are hybrid materials where the second component is usually air. Since air is much less dense than solid material, the air/polyurethane foam is lighter than bulk polyurethane.

Oct 29, 2026

Upload by jay