The primary goal of this work is to design and implement a clutch and brake system on the single tire Terramechanics rig of Advanced Vehicle Dynamics Laboratory (AVDL) at Virginia Tech. This test rig was designed and built to study the performance of tires in off-road conditions on surfaces such as soil, sand, and ice. Understanding the braking performance of tires is crucial, especially for terrains like ice, which has a low coefficient of friction. Also, rolling resistance is one of the important aspects affecting the tractive performance of a vehicle and its fuel consumption. Investigating these experimentally will help improve tire models performance. The current configuration of the test rig does not have braking and free rolling capabilities. This study involves modifications on the rig to enable free rolling testing when the clutch is disengaged and to allow braking when the clutch is engaged and the brake applied. The first part of this work involves the design and fabrication of a clutch system that would not require major changes in the setup of the test rig; this includes selecting the appropriate clutch that would meet the torque requirement, the size that would fit in the space available, and the capability to be remotely operated. The test rig's carriage has to be modified in order to fit a pneumatic clutch, its adapter, a new transmission shaft, and the mounting frame for the clutch system. The components of the actuation system consisting of pneumatic lines, the pressure regulator, valves, etc., have to be installed. Easy operation of the clutch from a remote location is enabled through the installation of a solenoid valve. The second part of this work is to design, fabricate, and install a braking system. The main task is to design a customized braking system that satisfies the various physical and functional constraints of the current configuration of the Terramechanics rig. Some other tasks are the design and fabrication of a customized rotor, selection of a suitable caliper, and design and fabrication of a customized mounting bracket for the caliper. A hydraulic actuation system is selected since it is suitable for this configuration and enables remote operation of the brakes. Finally, the rig is upgraded with the assembly of these two systems onto it. / Master of Science

Tire testing has been one of the important aspects of the tire industry because it helps identify the tire behavior which further helps in improving the design of tires. It also helps automotive manufacturers choose the best tire for their automobiles. Indoor tire testing helps in relating the data better because of greater repeatability of the testing setup as compared to outdoor testing. This study focusses on modifying a rolling resistance machine to make it capable of force and moment and cleat testing along with the standard rolling resistance test. Additionally, the design of a mechanical loading mechanism (used to apply normal force on the tire) in place of the previous one using dead weights is also discussed. This study also talks about the structural and vibrational finite element analysis of a tire testing machine. Since the machine was designed to conduct different tire tests, different structural requirements of the tire positioning mechanism pertaining to each test were taken into consideration, and the structure was analyzed for maximum forces and moments acting on the assembly. Cleat testing subjects the tire as well as the structure to an impulse force which calls for the vibrational analysis of the assembly to avoid the structure from resonating. The design was modified to get it easily manufactured and assembled. These design changes and the aspects taken into consideration have also been discussed. / Master of Science

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