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The Power Transfer Unit (PTU) provides full time, part-time or on-demand All-Wheel-Drive (AWD) torque distribution for Front-Wheel-Drive (FWD) based AWD systems. FWD has advantage in drivetrain efficiency and fuel economy, while AWD improves traction to have better acceleration and handling. Part-time and on-demand AWD have all the benefits of AWD and the efficiency of FWD. So AWD vehicle option continues to be popular around the world. However, Noise, vibration and Harshness (NVH) error state called PTU rattle has been detected in FWD mode of AWD systems due to torsional excitation. This study is one of the first to be focused on the PTU gear rattle as a NVH error state so far. We developed an AMESim-ADAMS co-simulation model for understanding PTU gear rattle phenomenon through drivetrain torsional responses (i.e. rotational degree of freedom, DOF) in system and PTU rattle assessment through PTU case vibration.

At various milestones during a vehicle’s development program, different CAE models are created to assess NVH error states of concern. Moreover, these CAE models may be developed in different commercial CAE software packages, each one with its own unique advantages and strengths. Fortunately, due to the wide spread acceptance that the Functional Mock-up Interface (FMI) standard gained in the CAE community over the past few years, many commercial CAE software now support cosimulation in one form or the other. Cosimulation allows performing multi-domain/multi-resolution simulations of the vehicle, thereby combining the advantages of various modeling techniques and software. In this paper, we explore cosimulation of full 3D vehicle model developed in MSC ADAMS with 1D driveline model developed in LMS AMESim. The target application of this work is investigation of vehicle NVH error states associated with both hybridized and non-hybridized powertrains.

The automotive industry is experiencing a profound change due to increasing pressure from environmental and energy concerns. This leads many automakers to accelerate hybrid and electric vehicle development. Generally hybrid and electric vehicles create less noise due to their compact engines (or no engine). However, customer satisfaction could be negatively impacted by the peak whine emitted by electric motor. Unlike conventional gas vehicles, the strategy for reducing motor whine is still largely unexplored. This paper presents an analytical study on electric motor whine radiated from the transmission in a hybrid vehicle. The analysis includes two stages. Firstly, a detailed finite element (FE) model of the transmission is constructed, and case surface velocities are calculated utilizing motor electromagnetic force. Then a boundary element model is built for evaluating noise radiated from the transmission surface using acoustic transfer vector (ATV) method.

Vehicle Noise, Vibration, and Harshness (NVH) performance has become an important indicator used in the “Customer Satisfaction” category in the automotive industry. Particularly, refinement of powertrain NVH performance in different vehicle operating conditions has had a major contribution to the perception of overall vehicle NVH performance. The powertrain system typically includes the engine and transmission (powerplant), driveline, axle, and induction/exhaust subsystems. This paper presents three areas of successful development work in resolving vehicle NVH issues using analytical and experimental tools: (1) powertrain bending induced vehicle NVH concerns at high speeds [1]; (2) exhaust modes induced - idle boom, vibrations, and normal vehicle speed moaning noise [2-3]; and (3) driveshaft modes and axle gear mesh force induced axle whine noise [4]. Each development work has resulted in design changes and improved NVH performance in production vehicles.