Biomedical Engineering Reference
In-Depth Information
into thinking lots of colors must mean the answer is right. You can be badly misguided by
“keyboard jockeys” (KBJs): those who own an analysis package but do not know how to use
it, properly . Unfortunately, due to the prevalence of available software and the misguided
notion that they are simply tools, there is also a prevalence of KBJs.
If you are using any computer-aided analysis packages make sure that whoever is producing
the model and analyzing the results knows what they are doing. Today there are too many
KBJs in the marketplace. If you are going to buy this service treat it as if you were going for a
major operation, i.e., make sure they are a qualified surgeon not that they have watched every
episode of Scrubs .
8.4.2 Computer-Aided Analysis Disciplines
While Table 8.2 attempts to convey the variety of analysis packages available, it is impossible
to illustrate all of them. However, what it does do is open your eyes to the wealth of
computer-assisted calculations. A word of caution: freeware and apps should be avoided. As a
medical devices manufacturer you should always use software that has been audited in some
form. You have no idea where an app or a piece of freeware has been written, so you have no
idea if it works or it doesn't. However, and MATLAB has started this, it is perfectly feasible
for the systems listed in Table 8.2 to be available for smartphones and tablets in the very near
If you are going to use one of these software items do not forget to put the decision and
reasons why in your calculation report.
To give you an idea of what can be achieved using modern CAA packages, Figure 8.2 has
been devised to illustrate an FEA analysis of a hypothetical implant. It is loaded at one
end and is held at the other by locking screws. The storyboard of figures illustrates how
the analysis takes the solid model derived from CAD (see later in this chapter) and produces
an FEA model from which a variety of solutions can be determined. In this case total
displacement (bending) and Von-Mises stresses have been illustrated. Using an accepted
FEA program is as valid as any hand calculation, but it is only one part of a rigorous
There is such a variety of computer-aided analysis packages available that virtually any
design can be analytically verified wholly by simulation. Indeed it is said that most modern
aircraft are validated in that fashion. However, as with aircraft, no one would consider being
the first passenger on the maiden flight if it had not flown somewhere already - hence it is
unlikely, in the near future, that CAA totally replaces physical verification. But it should be
stressed that using CAA saves time and hence cuts costs.
Figure 8.3 illustrates another typical CAA package: CFD. In this case a fluid is flowing into a
converging-diverging section of a pipe. Once again the storyboard illustrates how the model
is built. In this case velocity of flow and pressure profile are illustrated as flow lines.
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