Annex 5 — Reference data concerning seating positions 2. The application for approval of a vehicle type with regard to the protection of the occupants of the cab of a vehicle shall be submitted by the vehicle manufacturer or by his duly accredited representative. It shall be accompanied by drawings of the vehicle, showing the position of the cab on the vehicle and the manner of its attachment, and by sufficiently detailed drawings relating to the structure of the cab, all the said drawings being submitted in triplicate. A model for the information document relating to the construction features is given in Annex 1, Part 1.
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Lee, W. ABSTRACT This paper discusses the structural assessment of a heavy truck cabin with respect to occupant response in test designed to simulate a frontal collision. ECE R29 describes a series of test conditions to which truck cabins should comply, however these tests do not consider the occupant directly. The "swing-bob" dynamic test procedure prescribed by ECE R29 is used as a basis for assessing survivability. A computer analysis was performed and found that injury to the occupant in the lower leg region in this kind of impact is likely to be survivable.
As a result, the computational simulation of impact events and crash test procedures become of primary importance as it allows the designer to predict the behavior, take important conclusions and optimize the structure performance on the very early stage of development. It is important to notice the responsibility that DaimlerChrysler do Brasil has in this field, as far as the security of the occupants is concerned. The ECE R safety standard prescribes uniform provisions concerning the approval of vehicles with regard to the protection of the cab occupants of a commercial vehicle.
Its major goals are to evaluate the chassis frame-cab attachment in a situation of head-on impact and the overall cab strength, in order to eliminate to the greatest possible extent the risk of injury to the occupants. This is achieved by guaranteeing a survival space allowing accommodation of a prescribed manikin on the seat. The impact energy shall be 45 kJ for vehicles for which the permissible maximum exceeds 7, kg and 30 kJ for vehicles with maximum permissible mass under 7, kg.
The cab attachment to the chassis frame may be deformed, cracked or broken . This test method does not consider the fact that an occupant is mobile and can move during an impact test. It should also be considered that the occupant is mobile, and moves relative to the interior during typical impact test. This means that the assumption of a survival space made by ECE R29 is not accurate because the occupant does not occupy a fixed region in space throughout the test.
As ECE R29 aims to match impact energy, rather than test with a realistic impactor mass and initial velocity, the ability for this test to produce realistic loading of the occupant may be somewhat limited.
This model is commonly used worldwide for airbag and seatbelt design and is considered a valid representation of a real human . An existing model of a scissors-action truck was also incorporated into the model to represent the initial seated position of the occupant. The model geometric details are shown graphically in Figure 2. Contact interactions between the feet of the occupant and the cabin were defined to allow transmission of loads into the occupant legs.
As the swing-bob test results in symmetrical loading of the vehicle cabin, a symmetrical model was possible that would use only half of the truck cabin. The impact pendulum was modeled using a rigid body with an initial angular velocity of 2. Self contact was defined for the The configuration of the swing-bob test places the lower extremities of the occupant at most risk due to crush of the cabin.
For this reason, the primary occupant response of interest is the Tibia Index. This parameter is commonly used in passenger vehicle crash evaluations to understand the level of injury due to forces and moments applied at the ankle and knee of the occupant.
Thus four measures are made of the Tibia Index on the occupant, at the left and right ankle and the left and right knee of the occupant. It allowed us to take decisions on how to treat different material models and contact algorithms, intending to reach a better correlation.
Despite to transient deviation, shown in Figure 4, the intrusion results reach the same deformation when the swing-bob stops. In addition to the crush in the toe pan area of the cabin, the cabin undergoes a rigid body translation rearward as the pendulum accelerates it. It is the combined effect of the crush and this translation that produces the loading on lower extremities of the occupant.
Tibia index outputs from the model were quite low compared to the accepted tolerance value of 1. All other typical injury reference values Head Injury Criterion, Chest Acceleration, Chest Deflection, etc were, predictably, well below accepted tolerance levels. The kinematic results of the simulation are shown below in Figure 5. They demonstrate the tendency for the floor panel to buckle downwards due to the pendulum impact, and thus allow the toe pan area of the cabin to move towards the occupant, loading the feet.
This loading produces a moment on the ankles and a compressive force in the lower leg. These loads are combined together to calculate the tibia index injury parameter. The authors also wish to thank Mr. Spencer McKellip also for all his support during this work. Crush in the floor area may contribute to lower leg injury, though for the investigated case the level on injury is low compared to accepted injury tolerances used for passenger vehicle assessment.
This is unsurprising as the ECE R29 test uses equivalent energy levels, rather than realistic impact speeds, to represent the frontal impact case. As injury is highly dependent on impact speed, a more realistic method would be to reduce the inertia of the pendulum and have it impact the cabin with a higher speed, while keeping the energy level identical.
Despite this, numerical simulation in the early design phase offers the possibility to study both the structural requirements of ECE R29 and the likelihood of occupant injury based on more realistic criteria than a desired survival space.
Also demonstrated is the possibility for numerical simulation to be of use for investigation of other heavy truck safety issues, such as rollover , and cabin impact by freight. Tonioli, J. De Coo, P. Figure 5b: Cabin Post Impact.
ECE R29 PDF
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