Regenerative Braking Systems (RBS) provide an efficient method to assist hybrid electric buses achieve better fuel economy while lowering exhaust emissions. This paper describes the design and testing of three regenerative braking systems, one of which is a series regenerative braking system and two of which are parallel regenerative braking systems. The existing friction based Adjustable Braking System (ABS) on the bus is integrated with each of the new braking systems in order to ensure bus safety and stability. The design of the RBS is facilitated by Simulink [1] which is used to build an interactive, multi-domain simulator that is allows parametric variation of vehicle speed, State of Charge (SOC) for the batteries, and the maximum current to be allowed to the batteries from the RBS. The required braking forces as a function of wheel speed are modeled using dSpace[2]. A Hardwire-in-the-Loop (HIL) experimental setup is used for component testing, followed by road testing using the Chinese Urban Bus Driving Cycle. Results indicate that all three braking systems provide some energy recovery, with the serial RBS providing the best combination of energy recovery with acceptable drivability, safety and stability. Overall results confirm that regenerative braking systems can recover significant braking energy while operating in a safe and predictable manner.
In this study, we propose a new fiber metal laminate based on unidirectionally arrayed chopped strand (UACS) reinforced aluminum sheets, referred to as UACS/Al laminate. UACS is made by introducing slits into unidirectional carbon fiberreinforced plastic (CFRP) prepreg. Due to the presence of discontinuous fibers, the microstructure of the UACS/Al laminate is much more complicated than the conventional fiber metal laminate, which also results in a failure progression that is more complicated. Tensile failure of the UACS/Al laminate might occur as combination of intra-laminar damage at the slits, inter-laminar damage at the interfaces, in-ply damage of the CFRP, and plastic deformation of the aluminum plies. Fabrication and tensile tests of UACS/Al laminate specimens were performed. A two-dimensional finite element model was developed with intra-laminar cohesive elements inserted into the slits of the UACS plies and with inter-laminar cohesive elements inserted into the interfaces between all laminas in the modelled UACS/Al laminates. A numerical study is conducted to investigate the influence of the shape of the cohesive laws on the FEA predictions. The combined experimental and numerical studies provide a detailed understanding of the failure progression of UACS/Al laminates under tensile load.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.