De inklapbare container. Verificatie hangstangenconcept.
Report 2003.TT.5639, Transport Technology.
The research project "The collapsible container", of the Port of
Rotterdam and Delft University of Technology, revealed logistical and financial
opportunities of using collapsible containers. At this moment, many containers
are transported while they are empty. By using the collapsible container, five
containers can be stored as one.
In the same project, several concepts of this container are generated. One of
them, "crossbars", is promising and already patented. However, more
research and development is necessary before the container can be launched
into the market.
The tasks are very diverse. It contains aspects of construction, simulation and
creativity as well.
The concept of the crossbars must be worked out constructively. Moreover, we
are interested in the folding process of the container, which must be validated
by means of the multi-body program ADAMS. ADAMS should also be used to find the
best solution for the container concerning the link between the roof and the
sidewalls. Furthermore solutions need to be generated in order to set up the
The results of the simulations are summarized in an appendix to the report.
The dynamic behavior of the crossbars concept appears to be quite similar
with the concept of plates. For constructive reasons, the crossbars concept
is chosen for further examination.
The (reaction) forces in the simulation are used to calculate the dimensions
of the bars in the container. Detailed drawings of the construction (made in
Pro-Engineer) are contained in an appendix to the report.
To set up the container, several ideas are developed. According to a simulation,
setting up the container can simply be done manually. Concerning safety aspects,
the working conditions in the harbors are quite rough (e.g. the twist locks are
still being handled by hand below a loaded container). So it is open for
discussion. Another solution makes use of elastic cables. These will be
stretched while lifting the roof. The cables are attached in a specific way to
pull out the walls at the desired moment. This system is safe and can
efficiently be carried out by one person. However, the implementation of the
cables may increase the costs of the container.
The simulation model is slightly restricted in use. The reliability of the
maximum and minimum forces may be insecure. These lacks however, are inevitable
due to the nature of the problem. Consequently some parameters cannot be found
at the desired accuracy. Moreover the force vector substituting a joint is
necessary to avoid a redundant constraint (which in this case will crash the
model). This resuits in a higher local error in the integration process.
Therefore, a high safety factor should be applied for the maximum and minimum
forces (concerning the bars, a safety factor of five is applied).
The validation of the folding process is based on the results of the simulation,
as well as the associated analyses and plausible interpretation of the results,
The simulation model appears to be of great help for tracing problems. However,
the obtained results are not proportional to the invested time. Practically,
one should carefully consider whether there is a balance between the problem
and the time needed.
Reports on Transport Engineering (in Dutch)
, TU Delft