1. LECTURE 12.2

2. LECTURE OUTLINE Lesson 12 Quiz Lesson 12 Quiz

3. Table 1 shows some of the materials that were listed as Table 3.4 in the book. Use this information to answer the following question. The object is to design a scratch resistant counter-top for the kitchen. Which material would be employed for maximum scratch resistance? Soda-Lime Glass HDPE Tungsten Alumina Mullite

4. Table 1 presents some property measurements for a series of materials, whilst Figure 1 plots the Young's modulii of these materials as a function of their specific gravities. The line OP passes through the datum point for our benchmark material: aluminum. The datum point marked A on Figure 1 corresponds to: Alumina Tungsten Copper Mullite Nylon

5. Table 2 presents atomic numbers (At #), melting points (MP), specific gravities (SG) and Mohs' Hardnesses (H) for a series of metals, and their corresponding oxides. The specific gravity of a metal oxide increases as the specific gravity of the metal increases. Always true Sometimes false

6. Table 2 presents some properties of a variety of materials. Corundum is a Metal Ceramic Polymer Composite. Corundum is a compound; it is non-metallic, and inorganic; it is an oxide-ceramic.

7. Table 2 presents some properties of a variety of materials. Corundum is an ore for which metal? Magnesium Aluminum Manganese Iron Copper

8. Figure 2 shows the variation in the Specific Strengths of a series of composites (and see Chapter 27), as a function of the percent of glass-fiber in the composite. In order to attain a specific strength of approximately 105 MPa, the % fiber should be about 10 20 30 40 50

9. Table 3 presents the specific gravities, Young's modulii and yield strengths for a series of materials. The specific modulus of an alloy steel is approximately 26MPa 13GPa 128GPa 260GPa 1280GPa

10. Table 3 presents some property measurements for a series of materials, whilst Figure 3 plots the yield strengths of these materials as a function of their specific gravities. The line OP passes through the datum point for our benchmark material: aluminum. The datum point marked A on Figure 3 corresponds to: CFRP Titanium Alloys Alloy Steel Alumina GFRP

11. The semiconductor, gallium arsenide (GaAs) has a specific gravity of about 5.5, and a Young's Modulus of approximately 100GPa. The semiconductor, gallium arsenide (GaAs) has a specific gravity of about 5.5, and a Young's Modulus of approximately 100GPa. The location of GaAs on Figure 4a is at: A B C D E The location of GaAs on Figure 4a is at: A B C D E

12. The semiconductor, gallium arsenide (GaAs) has a specific gravity of about 5.5, and a Young's Modulus of approximately 100GPa. Is gallium arsenide a better, or worse choice than aluminum (our benchmark material), for an aircraft wing, based on specific stiffness alone? Better Worse

13. Table 1 presents some property measurements for a series of materials, whilst Figure 1 plots the Young's modulii of these materials as a function of their specific gravities. The line OP passes through the datum point for our benchmark material: aluminum. Which of the following materials would have a superior performance index for application as an aircraft wing, where a high value of Young's modulus, and a low value of specific gravity are desirable? Alumina Tungsten Nylon Copper.