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to several problems with small changes.
The example which is presenting here is the
parametric design of a loft. This problem involves
the design skills of the students. It is also a good
example of how to combine the masteries of
CAD and programming to design an educational
appliance.
The design of pillars, beams, stairs and the
parapet requires particular knowledge of different
courses and push the students on the use of local
or international norms, as a structure addresses
many people and high safety standards have to
be concerned. To design such structure weight
and properties of different materials (steel, wood,
plastic, etc.) used to build it have to be considered.
On the other hand taking in to account different
input variables needs a parametric design.
Excel®, Calc, Numbers, Matlab®, Octave
and much other software can be used. Even some
freeware software may provide enough profes-
sional capabilities. Considering the necessity of
application of a spreadsheet Microsoft® Excel®
can be a good choice as it is a standardized util-
ity in many factories and universities. The use of
a spreadsheet let the students to design easily a
user interface where inputs and outputs are well
presented and also where all the materials are
written in tables, equipped by all their properties
needed for the design.
Once introduced the inputs, a series of well-
linked cells may lead to a series of outputs giving
us the opportunity to draw the complete structure.
However this is possible only if simple approaches
are to be used. The task shows itself more strongly
concerning to the fact that the iterative design is
not always accessible (especially if the design
presents several branches). In this case the con-
nection between the cells may become incredibly
complex or even impossible. Moreover the debug
of the algorithm will be a very complex task as
well. Thus the use of Visual Basic® for Applica-
tion may solve these limits and let the student to
embed the design algorithm inside the spreadsheet,
but using a simple programming language.
The students have to study all kinds of simple
structures that constitute the loft such as beams
and pillars and draw the designs by hands. The
algorithms have to be solved leaving parametric
input variables. They have to be able to distinguish
all the limits in the calculations and designing in
order to encounter the warning and error mes-
sages that they will face with during using the
e-tool approaches caused by applying improper
combinations of values of the parameters.
The present spreadsheet is able to design even
each small bolt. To avoid the time consuming step
of updating all the dimensions by the designer after
making each kind of changes and moreover, to
prevent the errors due to the accidental forgetful-
ness the worksheet has been connected directly
to a CAD system. Thus it allows the drawings
to be updated automatically at each change of
the input parameters. Finally thanks to realistic
rendering software like Blender or 3DStudio it
is possible to convert the engineering drawing
of the structure to a more desirable “realistic”
representation (Figure 6).
In this example all calculations are considered
and solved by VBA (some of them in closed form,
others by iterative calculations). The cells of the
spreadsheet are organized in a way that the user
finds easily the series of necessary input and
the series of important output. Using a 3D para-
metric CAD software like SolidEdge®, the user
can connect the output cells of the spreadsheet
(representing all the dimensions of all the part of
the loft) to the CAD system using OLE (Object
Linking and Embedding) approach. To do this the
CAD model of the loft has to be drawn and each
dimension has to be linked to the spreadsheet.
In different fields of engineering, the study
of the influence of pores on the fatigue life of
mechanical parts is a very important task. In fact
the pores are defects of empty volumes presenting
in material due to the production process and are
very expensive to reduce or control.
Recent studies on this area are more focused
on a better understanding of the influence of the
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