Western Michigan University
A team of 18 students, at Western Michigan University (WMU), has been working on a project to improve heavy truck stability. The project is sponsored by the National Transportation Research Center, Inc. (NTRCI), in Knoxville, Tenn. through WMU's Center for Advanced Vehicle Design and Simulations (CAViDS). The primary benefit of the research will be to save lives because 52 percent of all truck driver fatalities are the result of rollovers. The students have been involved in all areas of the project including instrumenting vehicles, calculations, modeling, and verification.
Several software tools have been used on the project, but Adams is playing a more significant role as the project moves forward. Adams is being used because it allows the team to study areas that the other tools simply cannot. For example, Figure 1 shows a full flexible-body model of a tractor trailer using modal neutral file bodies. This particular study was done for the Tank Automotive Research, Development and Engineering Center (TARDEC).
Figure 1 Full flexible body model of a tractor-trailer.
The power of Adams modeling can be seen in Figure 2 where one node on the model has been selected to study the strain history during a lane change maneuver.
Figure 2 A time history of strain on a node in the model.
The strain history of this node was then compared to data taken from a strain gage mounted on the trailer axle at a similar location (Figure 3). The strain gage data in Figure 3 has been highlighted in a bounding box to correspond to the Adams output. With the exception of the noise from the strain gage, one can see the there is good agreement in relative amplitude and periodicity with the Adams model.
Figure 3 Adams output compared to strain gage data.
The current vehicle of interest is a tractor and tanker-trailer. The team used an optical digital scanner to aid in generating the solid models shown in Figure 4. The components of these models are being meshed to then generate modal neutral files for the flexible bodies in Adams (Figure 5).
Figure 4 Tractor and tanker-trailer solid models.
Figure 5 Meshing the components of the model.
Finally, Figure 6 shows the mesh of the tanker body followed by a verification of one of its vibratory modes.
Figure 6 Mesh of tanker body and its first free-body mode of vibration
Reports pertaining to this work and previous work leading up to this work are available at www.ntrci.org.
Dr. Mitch Keil