Page 19 - 360.revista de Alta Velocidad - Nº 5

Lightweight primary structures for High-speed railway carbodies

The use of new methodologies for design (FEM+Multibody Simulation) together with of

operational/experimental modal analysis allows the understanding of the behaviour of the new
structures regarding vibration and comfort. In addition, it is also checked the effectiveness of
the general rules explained above applied in a very specific product like Talgo’s trains (non-
standard running gear, short, wide and light vehicle).
The structures of the AVRIL’s coaches are made by an optimum combination of open and closed
profiles with variable inertia to achieve the strength of the carbody. In order to improve the
stiffness of the carbody stiffeners and reinforcements inside and outside are welded to the
main structure to achieve an assembly very stiff and light. With the new profile architecture is
possible to have a bigger structure (mainly wider) saving around 10% in weight compared to the
structure of the previous high speed Talgo’s coaches (S102/112).

First step is performed a complete modal analysis with a finite element program to estimate
the natural frequencies and mode shapes. Mainly we are focused on the first mode shape,
frequency and if it is a local mode or a mode for the complete structure (modal mass). The
analysis is done in different mass condition (full and empty).

For example in the Figure 8 is shown the 2 flexural mode of the main frame of the
nd
prototypcarbody, in this case at 20Hz.

Figure 8. Modal FEA. 2nd flexural mode at 20Hz of the main frame of the prototype carbody

This approach is very accurate when the Eigen frequencies are far from the running gear
excitation. For this reason, together with modal FEA, a combined analysis with multibody and
finite element is done to assess the separation between the Eigen frequencies of the running
gear at train level and the flexible carbody. It is very important when you have a lot of interfaces
with the carbody like in the Talgo case: guidance system, secondary suspension, dampers.
In addition to computer design different analysis was made in the prototype carbody. Operation
modal analysis (OMA) and Experimental modal analysis (EMA) would be a useful tool to obtain
the real mode shape and frequencies. OMA is a modal analysis using operating conditions as
excitation in contrast to EMA that uses defined and controlled excitation.

International Congress on High-speed Rail: Technologies and Long Term Impacts - Ciudad Real (Spain) - 25th anniversary Madrid-Sevilla corridor 17