Modeling

Modeling has been categorized into three section in this report.

1.       Vehicle modeling

2.       Guardrails and joints modeling

3.       Soil modeling

Hypermesh has been used as the main software for preprocessing tool and all simulation have been performed in LS-Dyna.

Vehicle modeling

In this simulation two vehicle model have been used, a four-door sedan and a pickup C2500.

Pickup vehicle

The complete C2500 finite element model has been used in all simulation without any modification. Modeling data are shown in the following table.

The tires have been modeled with airbag simple pressure volume code and the coefficients are listed below.

Whereas the tire pressure can be calculated with the following formula:

Sedan vehicle

To evaluate the crash simulation of a sedan vehicle, a Taurus vehicle model has been used that unlike C2500, it has been modified and corrected for the simulations. The model data are listed in the table below.

Guardrail modeling

A total of nine guardrails have been assembled together with 4 bolts in each side of a rail. Both joint rails are bolted to a base that is fixed in ground. Dimension and material properties will not be published. However, modeling data are listed below.

Bolts and nuts have been modeled with rigid materials connected via a spring with failure deflection that is relevant to bolts’ ultimate stress.

Soil modeling

The soil has been modeled with mat_soil_and_foam without any reinforcement. There are some other methods that use grout and steel in the soil while I have neglected them. Material coefficients with detail of finite element modeling can be seen in the figures below.

Creating contact

Totally, the contacts can be categorized according to their assemblies. Friction coefficient have been widely used in all contacts

1-      Between vehicle parts

2-      Between rail, base and vehicle

3-      Between base and soil

Loading

Vehicle is about to impact guardrails with angle of 25deg and a longitudinal velocity of 80km/hr. Furthermore, a rotational velocity has been set to tire too.

The soil lowest nodes have been considered as fixed condition and also boundary nonreflecting condition has set to soil exterior nodes.

Pickup results

Time 0.1s

Time 0.6s

From the figures, it can be discovered that vehicle velocity reached to 25km/h from 80km/h during 0.6sec. The pickup deviated maximum of 8 degree from longitudinal axis and had reached a peak of 5 degree in roll angle.

The final deformation after a 0.6 simulation can be seen in the following figures.

Sedan results

The whole deformation after 0.6s is shown bellow.

Sedan Impact 0 deg

The vehicle absolute pitch angle can be seen bellow. Vehicle pitched about 9deg.

 To see the animation of pickup model click on the following link:                                          Animation