tailieunhanh - Vehicle Crash Dynamics P4

The power rate densities based on the original FEW coefficients and the all-negative coefficients for the three full-size vehicle tests are shown in Figs. and , respectively. Note that in Fig. , the must-activate tests, #2' and #3', are well separated from the #1 test after the introduction of the all-negative coefficients. In crash severity analyses using power rate density (prd) and FEW coefficients, it has been assumed that the FEW coefficients be given before the prd computation. The application of the methodology to real time sensing application, however, needs to be explored further. Nevertheless, the analysis points out. | The power rate densities based on the original FEW coefficients and the all-negative coefficients for the three full-size vehicle tests are shown in Figs. and respectively. Note that in Fig. the must-activate tests 2 and 3 are well separated from the 1 test after the introduction of the all-negative coefficients. In crash severity analyses using power rate density prd and FEW coefficients it has been assumed that the FEW coefficients be given before the prd computation. The application of the methodology to real time sensing application however needs to be explored further. Nevertheless the analysis points out the unique features of the FEW coefficients in the non-perpendicular barrier tests where the coefficients can be manipulated and the crash severity can then be distinguished. Use of Pulse Curve Length in Crash Severity Detection An algorithm using the curve length concept to analyze vehicle crash severity is explored here. Its purpose is to test its usefulness in discriminating non-perpendicular impacts such as the rigid pole test and for meeting the desired sensor activation criteria. Since curve length of a crash pulse depends on how the crash pulse is filtered the use of the same filtering technique for different impact modes is necessary. In the algorithm based on the curve length concept it is postulated that the curve length of the crash pulse in a softer impact such as an 8 -diameter rigid pole test is longer than that in the perpendicular rigid barrier tests. The computation of the curve length L of a given crash pulse can be carried out using the notations shown in Fig. and algebraic relationships shown in Eq. Fig. Crash Pulse Data Points from Fig. AZ curve length of a crash pulse SL . length of line segment j k AL - S AZ. where j i k no. of line segments in the crash pulse A 2 A 7 2 Aiy m2 4 4-i and As- A4. m. . slope of line segment j The test data from the four mid-size vehicle tests shown in Table