Department of Mechanical Engineering

Mr. David Wafer

Degree Candidacy: Master of Science in Mechanical Engineering
Date: Tuesday, April 22, 2014
Time: 3:00 PM
Location: 108 EIB

Chair: Dr. Mohammad Daqaq
Committee Members: Dr. Harry Law and Dr. Beshah Ayalew

Title: Lateral Dynamics of Multiple Trailer Trucks in Windy Environments

ABSTRACT

The lateral response of three-trailer commercial vehicles has been assessed using the simulation package TruckSim™. Aerodynamic and mechanical characterizations for the vehicle were developed for this investigation.

Simulations were carried out with various aerodynamic and load configurations with several different arbitrarily defined crosswinds.

The aerodynamic configurations were tested in constant and random crosswinds. The load configurations were tested only in random crosswinds. Each aerodynamic configuration differed by the aerodynamic side force coefficient for the trailers. Each load configuration consisted of reducing the payload in a single trailer. The tractor was identically defined for each load and aerodynamic configuration.

Increasing the aerodynamic side force coefficient for trailer 1 decreased the lateral displacement of the vehicle. Decreasing the aerodynamic side force coefficient of trailer 1 increased the lateral displacement of the vehicle. This was observed for both constant and random crosswinds.

Increasing or decreasing the aerodynamic side force coefficient of trailers 2 and 3 increases or decreases (respectively) the relative displacement of each trailer to its preceding unit.

Reducing the payload for trailer 1 by 50% (while leaving the remaining trailers fully loaded) dramatically reduced the lane displacement. Reducing the payload by 50% in trailers 2 and 3 resulted in performance nearly identical to that of a fully loaded vehicle.

Driver workload was assessed from random crosswind simulations in the categories of mental effort, physical effort and path error. The vehicle, as expected, became more difficult to drive with increased average wind speed. Configurations exhibiting smaller lane displacements usually resulted in reduced physical workload but not necessarily reduced mental workload.