In the cross configuration, two continuous SMA wires are
wound around the rubber bearing diagonally as shown in Fig. 1b.
A steel hook is mounted at each corner on the lower surface of
the top supporting steel plate and on the upper surface of the bottom supporting steel plate. The SMA wires pass through these
hooks (Fig. 1b). The main reason of using wires in such an arrangement
is to effectively reduce the maximum strain generated along
the wires compared to the straight configuration (Fig. 1a).
The total length of wires needed for this arrangement is presented
in Table 2. Although a larger length of SMA wire is required
for this configuration relative to the straight one, the generated
strain in wires due to the lateral deflection of rubber bearing is
much lower.
Fig. 2b shows that in the case of cross configuration there is a
significant reduction in the SMA wire strain compared to the
straight configuration (Fig. 2a). At 200% shear strain amplitude
with an aspect ratio of 0.36, the maximum strain induced in the
SMA wires does not exceed 9%. It shows that unlike straight configuration
in which SMAs can operate in a limited range of c and R,
different types of SMA can be used in the cross arrangement.
Fig. 2b illustrates that at each shear strain level, the strain in the
SMA wires reaches its maximum value when the smart elastomeric
isolator has the maximum considered aspect ratio.