Page 120 - 04. Subyek Engineering Materials - Manufacturing, Engineering and Technology SI 6th Edition - Serope Kalpakjian, Stephen Schmid (2009)

Synthesis, Design, and Projects 99
|]3.22. It can be shown that thermal distortion in precision ]/cm3 K. Compare the results to the value for liquid water
devices is low for high values of thermal conductivity divided (4.184 J/cm3 K). Note that the volumetric heat capacity of a
by the thermal expansion coefficient. Rank the materials in material is the product of its density and specific heat.
Table 3.1 according to their ability to resist thermal distortion.
3.24. Conduct a literature search and add the following
|]3.23. Add a column to Table 3.1 that lists the volumetric materials to Table 3.1: cork, cement, ice, sugar, lithium,
heat capacity of the materials listed, expressed in units of chromium, and platinum.

SYNTHESIS, DESIGN, AND PROJECTS

3.25. From your own experience, make a list of parts, com- 3.30. The maximum compressive force that a lightweight
ponents, or products that have corroded and have had to be column can withstand before buckling depends on the ratio
replaced or discarded. of the square root of the stiffness to the density for the mate-
rial. For the materials listed in Table 2.2, determine (a) the
3.26. List applications where the following properties
ratio of tensile strength to density and (b) the ratio of elastic
would be desirable: (a) high density, (b) low density, (c) high
modulus to density. Comment on the suitability of each for
melting point, (d) low melting point, (e) high thermal conduc-
being made into lightweight columns.
tivity, and (f) low thermal conductivity.
3.3 I. Describe possible applications and designs using alloys
3.27. Describe several applications in which both specific exhibiting the Invar effect of low thermal expansion.
strength and specific stiffness are important.
3.32. Collect some pieces of different metallic and non-
3.28. Design several mechanisms or instruments based on metallic materials listed in Table 3.2. Using simple tests
utilizing the differences in thermal expansion of materials, and/or instruments, determine the validity of the descending
such as bimetallic strips that develop a curvature when order of the physical properties shown in the table.
heated.
3.33. Design an actuator to turn on a switch when the tem-
3.29. For the materials listed in Table 3.1, determine the spe- perature drops below a certain level. Use two materials with
cific strength and specific stiffness. Describe your observations. different coefficients of thermal expansion in your design.