*3.2. Results of Harness Loading*

The aim of the test was to progressively load the harness up to the force corresponding with the maximum opening shock load generated by the canopy during the activation phase. The gradual loading process will help to obtain information on whether the individual straps are taking the same percentage of the total applied force during all processes. If the test results show that there is a uniform percentage redistribution above a certain load value that does not change further, the results of this study can be used without regard to the opening shock load magnitude. In other words, the loading of the individual elements would then only be determined by the total applied force and the redistribution factor based on this research. As the result shows, this will play a major role in the investigation of the element's safety margin.

Based on the load output from the drop test, the maximum required force has been established as 8000 N. In order to not distort the data due to the initial settling of the harness on the dummy, a preload of 1500 N was applied before each test. This level of preload was set by an estimation. Above this value, there was no further movement of the harness on the dummy's body.

It must be noted that the values of the force recorded by the station also include the weight of the dummy and hanging devices. Hence, some postprocessing was necessary to have comparable results. The presented values of the forces are zeroed at the beginning of the test. This ensures that the weight of the equipment and the initial tension of the webbing are no longer present. As a result, the data only represent the value increment gained from main loading force redistribution into individual segments.

The maximum applied forces are not totally identical between the separate cases. The reason for this is that the readout of the forces was performed manually. Once the operator saw the desired load on the display, further loading was stopped. These small differences do not affect the evaluation of the individual tests. Only the parameters from the separate test entered the analysis of the load capacity, followed by a recalculation of the critical element's theoretical load capacity at a given configuration. The subsequent comparison in Table 1 includes a conversion to the theoretical critical force, which can already be used to compare the harness load capacity for different configurations.


**Table 1.** Complete results of the maximum forces during loading.

In general, all test cases have the same evolution, where four main stages can be identified:


The first stage is, in general, caused by the difference in position of the center of gravity of the steel dummy and the point where the dummy is fixed to the ground of the test room. During the first seconds of loading, the dummy is rotating to the new equilibrium state, which is not changing significantly during further loading. The position change is highlighted in Figure 10.

During the second phase, the system stops rotating and only the harness itself begins to show signs of slight movement on the dummy's body. This is clearly visible in the chart showing the load profiles of the individual elements. Once the load exceeds a certain value, the harness is already static, and there is a steady increase in force. This phenomenon allows the referenced generalization of the published results to use this procedure for a different opening shock load. The assumption is that if a higher load was applied, it could be expected to increase in separate positions with respect to the obtained redistribution ratio. This is one of the most important findings. This idea is possible to apply to all six tests, which enables the calculation of the theoretical limit load of the harness for all the configurations.

The fourth point of the observation showed undesirable conditions. The buckle located on the right leg webbing started to gradually and irregularly loosen once the overall load exceeded the value of around 3000 N. This could be caused by the wear of the buckle, the hard base under the buckle, or a combination of both phenomena. The relaxation was gentle and did not affect the final results presented.

The load redistribution of the total applied load into individual load cells is shown for all six tests in Figures 11–16.

**Figure 10.** Rotation of the dummy during the first stage of test case one: (**a**) Unloaded, and (**b**) loaded.

Figure 11 displays the load profile of the test configuration one. Progressive loading began at force 0 N, which represents a steady state in which the harness is only loaded by gravity and tightening the webbings to fit the dummy. Loading was stopped at the maximum overload value of 7665 N. Above the value of 4000 N, forces are already steadily distributed, and the same slope of the curves is observable. The load in elements one and two differs by 120.9 N. It can be assumed that this difference in load is transferred by the chest strap, which was tightened.

**Figure 11.** Total force redistribution into individual load cells during test one.

Figure 12 displays the load profile of the test configuration two. During this test, the force applied to the right connection points of the harness was two times higher than to the left side. This resulted in higher loading of the chest webbing and bigger differences between the loads in positions one and two Loading begins at 0 N and increases to a maximum of 7699 N, as in the previous test. Unlike the first test, the forces were already evenly distributed once the total applied load reached a value of 1000 N.

**Figure 12.** Total force redistribution into individual load cells during test two.

Figure 13 displays the load profile of the test configuration three. During this test, the force applied to the left connection points of the harness was two times higher than to the right side. This resulted in a different redistribution pattern. The load cell one measured a lower load than the load cell two. Loading started at 0 N and reached a maximum of 7599 N. The forces were evenly distributed once the total applied load reached 3000 N.

**Figure 13.** Total force redistribution into individual load cells during test three.

Figure 14 displays the load profile of the test configuration four. The dummy was fixed in place and rotated face down during this test. This resulted in a loosening of the back straps, which were not carrying any load. Loading started at 0 N and reached a maximum of 7735 N. During this test, load cells in positions one and two measured similar forces throughout the whole process. As in the second test, once the total applied load reached 1000 N, the forces were already evenly distributed.

**Figure 14.** Total force redistribution into individual load cells during test four.

Figure 15 displays the load profile of the test configuration five. The dummy was fixed in place and rotated backwards during this test. This increased the loading on the back straps. Loading started at 0 N and reached a maximum of 7748 N. During this test, load cells in positions one and two measured similar forces throughout the whole process. The forces were evenly distributed once the total applied load reached 2000 N.

**Figure 15.** Total force redistribution into individual load cells during test five.

Figure 16 displays the load profile of the test configuration six. During this test, the chest webbing has been loosened. This resulted in lower loading of the chest webbing compared to test one, which has the same setup but with tightened chest webbing. Loading started at 0 N and reached a maximum of 7787 N. The forces were evenly distributed once the total applied load reached 1000 N, the same as in the second test.

**Figure 16.** Total force redistribution into individual load cells during test six.

Table 1 summarizes the measured forces in separate load cells with respect to the maximum applied force, which is also highlighted. The marking of the separate elements is performed according to the established convention. As already discussed, the peak of the applied force is not identical for all test cases because of the delay between switching off the load hydraulic cylinder, which was mechanically operated. Nonetheless, the evaluation of the results within the single tests has no effect on the results of the subsequent load capacity analysis.
