JEC COMPOSITES MAGAZINE - Issue #96 - April 2015 - 28

cost-effectiveness

Cost modelling of composite structures

By
Mathilda Karlsson Hagnell, PhD student
Malin Åkermo, Associate Professor
Department of Aeronautical and Vehicle
Engineering
KTH (Royal Institute of Technology),
Sweden

T

o be successful, a design has
to be producible, which means
its manufacture must be
cost-effective at the required annual
production rate. This is especially
true for composite design solutions,
where it can be difficult to choose
and match the appropriate production method with the necessary cost
at a high-enough production rate.

Cost-effectiveness
The importance of the cost-effectiveness of a production is relative, and depends on the industry.
In aerospace, a lighter composite
structure is of high value as lower
weight contributes to lowering fuel
consumption. In this case, a higher
production cost can be warranted.
To accurately reflect the value of
such a design, it is therefore necessary to size the production cost with
respect to weight. This idea results in
a trade-off between weight and producibility, or rather, production cost.
To this end, the authors are develop-

In aeronautics, composite materials are weight-efficient but
difficult and often costly to produce. To study this contrast,
the authors are working on a methodology where the costs
of composite manufacture and assembly are estimated as a
function of structure geometry, complexity and manufacturing approach.

ing a novel methodology and production cost estimating tool that makes
it possible to analyse the trade-off
between the cost and weight of a
generic composite structure, and
enables direct comparative studies of
different composite design solutions.
Due to the investigative nature of
such an analysis, the cost estimation
tool targets the conceptual design
stage, where the level of detail is low.
This means the tool shows general
trends and comparative measures
rather than absolute values. The advantage with such a tool is its ability
to quickly compare general trends for
different manufacturing approaches
and design solutions.

and the costs are summarized (see
figure 1).
The production cost is considered
to be a function of the set manufacturing method. Therefore, it is
necessary to compare the predicted
production cost of all the considered
manufacturing methods to seek the

Production cost
The cost estimation tool is developed
in Python, and is based on process
modelling through determining and
describing the governing process
steps for any given manufacturing
method. The necessary component
data is extracted from a CAD file to
allow for simple use. The involved
cost drivers are defined for each step

28 jec composites magazine / No96 April 2015

Fig. 1. The cost drivers accounted for in the current model are marked in grey; the neglected
ones are marked in white
JEC COMPOSITES MAGAZINE - Issue #96 - April 2015

Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #96 - April 2015
