THE ROLE OF THE

60 The Role of the Chemist in Automotive Design
can be excited in various patterns at different frequencies. This property is an indication
of the part’s stiffness and is proportional to the square of the stiffness divided
by the mass or
f =
stiffness
mass
Another very important predictive output is the amount of deformation that the
material is subject to. These are typically called total displacement plots, as shown
in Figure 4.17. In our example, the beam was displaced 2.003 mm.
4.7 PredIctIve desIgn For tHe cost ImPeratIve
Optimizing design for the cost imperative is critical for today’s applications. Performance
to cost design is affected by a number of factors. These factors include material cost,
processing cost, tooling cost, secondary cost, and inventory cost. The simple spreadsheet
shown in Figure 4.18 can be used as a guide to help understand and track raw material
cost. Typically, the chemist would approximate the length, width, and height to get an
approximate volume for the part. The material quantity can then be calculated from the
part’s volume and density. The material quantity is corrected for material scrap loss. The
price per pound or kilogram minus overhead will then give the total material cost.
Manufacturing cost can also be comprehended by the use of a spreadsheet and
some knowledge of the process. Figure 4.19 shows manufacturing costs that should be
considered. The equipment purchase price is considered along with the amoritization
rate, number of shifts, interest rate on the equipment, energy cost for the equipment,
and floor space cost. Equipment time rate should be considered. The equipment time
FIgure 4.17 Part with cantilevered beam showing total displacements.