Tech Articles

How to use multiple roads with FTire


Tech Articles ID    KB8024065
Status:    Published
Published date:    05/25/2020
Updated:    05/25/2020
Reported In:   Adams (Not Release Specific) - Adams Car
Created with Version:   Adams (2020)
 

Abstract (Question)

In general a tire model in Adams can have contact with one road, however the CTI interface used by FTire allows to use a tire to be in contact with multiple roads, for example a tire driving over a cat eye on the road that has a flexible base.

 

Description (Answer)

 

Demo with FTire multi-road feature

 

This document describes the use of FTire with multiple road sections using the MDI_Demo_Vehicle.

The example shows the vehicle driving over a bump which is suspended to ground by a bushing. Due to the low stiffness of the bushing the tire will push the bump down into the road.

The example_demo_multi_road.cmd sets up the model, it will load the MDI_Demo_Vehicle assembly. Next, the script add_road_part.cmd is imported, which will add the second road part bump to the MDI_Demo_Vehicle assembly. Then the tires of the vehicle are changed to FTire’s and a maintain simulation is started.

The add_road_part.cmd will add all components need for the second road part:

·         The additional (second) road part, the base for the bump as defined in the 3d shell road file

·         a bushing in between the second road part and the ground

·         the additional forces (gforces) of the tires on the road part (bump). For each tire one additional gforce.

When a tire hits the bump, the road part will sink down when the tire is rolling over the bump (because of the low stiffness of the bushing):

 

For details of the add_road_part.cmd, see the comments in this script. The additional forces refer to the additional road part as defined in the 3d shell road file:

!                 adams_view_name='TR_Front_Tires.plank_force_1'

GFORCE/10

, I = 1161

, JFLOAT = 1162

, RM = 834

, FUNCTION = USER(908, 2, 1170, 2)\

, ROUTINE = abgTire::gfo910

 

The geometry of the road is defined in the 3d shell road file, body 1 is ground, body 2 is the additional road part as identified by the additional gforce above:

NOTE: the nodes of the shells must be defined in the right order. The rotation order will define the direction of the normal of the shell element, which must point upwards!

The evaluation method for the shell road must be set to ‘FULL_3D’:

If another road part would be added, a body id 3 should be introduced to the road file, and 4 additional tire forces need to be added, one for each tire.

 

NOTE: for the road type visualization within the FTire on-line simulation, the option ‘road-type specified grid’ should be selected:

English Attachment

demo_multiple_road.7z
6MB • 18 minute(s) @ 56k, < 1 minute @ broadband



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