&quot; t1 &quot; and &quot; t2 &quot; are the two time instants (expressed in seconds) during the impact, defining an interval between the beginning and the end of the recording period for which the value of HIC is a maximum (t2 t1 &lt; = 15 ms).
t1 et t2 = instant marquant l &apos; un le début et l &apos; autre la fin de la période pendant laquelle la valeur HIC atteint son maximum (t2 - t1 &lt; = 15 ms).