smart technologies for safety engineering

Dynamic Load Monitoring 113
the second impact phase was 120–150 ms, while the duration of the whole phenomenon for
the analysed structure was 170–200 ms.
4.1.6 Experimental Verification
The impact identification approaches proposed in the previous subsections were verified experimentally
with the described laboratory test stand. Each of the approaches was tested with
a wide variety of 56 different impact scenarios admissible by the stand:
seven masses spaced in the range 7.2–37.2 kg;
eight drop heights equally spaced in the range 0.05–0.40 m, which corresponds to the impact
velocities in the range of approximately 1–2.8 m/s.
4.1.6.1 Solution Map Approach
The objective was the maximum simplicity of the data acquisition set-up, i.e. to apply an
algorithm able to operate on the basis of measurements from one sensor only. Moreover,
an important issue was to use a sensor that was not directly fixed to the falling mass.
It was decided to use the force sensor. Two impact parameters (mass m and velocity v
of the falling body) had to be identified using the single force sensor. Therefore, in order
to construct the solution map, at least two characteristic quantities had to be extracted
from only one measured force history. Figure 4.8 shows an example of force measurement
Figure 4.8 Measured impact force evolution and parameters used to construct the solution map