Civil Engineering Reference
In-Depth Information
Fig. 6.8
Stationary maximum temperature response of experimental and model results for
remaining parameter sets [
4
]
The remaining stationary maximum temperature profiles for the other param-
eter sets are summarized in Fig.
6.8
to display the validity of the established pro-
cess variables that were held constant while only modifying the electrical input
parameters. As can be seen in the figure, the model was capable of matching the
experimentally observed thermal response (maximum error is less than 2 °C).
Also, the maximum temperatures reached can be observed for the varying electri-
cal conditions, and the higher current with the middle pulse duration produced the
largest temperature.
Upon validation of the stationary model, the thermal response for the case with
deformation was examined. The maximum thermal profile for an experimental sta-
tionary and deformation test is displayed in Fig.
6.9
. As can be seen, the stationary
curve maintains a constant maximum temperature, whereas the deformation curve
response increases as time progresses. This increase in the maximum temperature
is a result of the elongation and shrinking cross-sectional area which modifies the
resistance of the sheet and thus the heat generation per unit volume. Additionally,
with deformation, the heat transfer conduction area decreases and convection
area increases which influence the cooling during and after the applied electrical
current.
The models created to account for deformation are compared to the experimen-
tal results in Fig.
6.10
for Parameter Set 4. As can be seen, the uniform model
underpredicts the thermal response as a result of the assumption that only uniform
deformation occurs during the process even though it assumes that all of the input
