The multiple-order response of a rotor equipped with a centrifugal pendulum vibration absorber (CPVA) is investigated in this study. CPVAs have been used in the abatement of torsional vibrations since the 1930s and have been extensively researched but seldom with a focus on the full multiple-harmonic response. Although the firing order in reciprocating engines dominates in amplitude, the higher-order harmonics have impact on driveline-related noise issues. This investigation is conducted in order to understand if an higher-order amplification can stem from the design of the CPVA or if this phenomenon is due an interaction between other powertrain components. Therefore, an isolated rotor-CPVA system is studied. The investigated rotor is subjected to an oscillating torque consisting of single- and multiple-order harmonics. The equations of motion are derived by Kane s method and the multiple-harmonic response of the system is analyzed. The linear steady-state response is compared with numerical time integration of the equations of motion.

A model of the normal-force dependant friction loss between the rotor and pendula is developed for bifilar centrifugal pendulum vibration absorbers (CPVAs). The normal-force is dominantly dependant on the rotor rotational velocity but also dependant on the pendulum path. Simulation results of the pendulum with the proposed normal-force friction model agree well with novel experimental results. Order-response simulations of the rotor-CPVA model with the proposed friction model reveal accuracy improvements on the prediction of the rotor oscillation amplitude at different rotational velocities in comparison to existing friction formulations. Derivation of the equations of motion of the rotor-CPVA is performed by Kane's method and solved numerically. The developed experimental setup is used to validate the model parameters such as friction coefficients, path parameters and relative pendulum rotation without necessitating a special test-apparatus other than standard vibration measurement equipment. CPVAs are commonly used to reduce torsional vibration created by reciprocating engines. To reduce emissions, heavy-duty vehicles manufactures are downsizing and downspeeding the combustion engine while maintaining the power output. Unfortunately, this gives rise to increased torsional vibration in the powertrain. The CPVA is a device that can reduce the torsional vibration and thus help fulfill environmental goals.

The performance of the centrifugal pendulum vibration absorber (CPVA) is investigated in the low rotational-speed regime in the context of a heavy-duty combustion engine. With the given dimensions and properties of heavy-vehicle engines, special considerations must be taken into account in the analysis of the CPVAs in the low speed regime. In this study, bifilar-suspended pendula absorbers attached to the engine flywheel, tuned to absorb the main engine firing order, is modeled analytically. Friction damping is included in the pendulum model and the effects of the performance by varying the pendulum path curve is studied in the low rotational-speed regime. The low rotational-speed is due to engine down-speeding, resulting in excessive torsional vibration in the driveline. In order to maintain or improve NVH and fulfill legal requirements, the excess torsional vibration must be addressed to gain the emission benefits of down-speeding. Simulation and analysis of the CPVA behaviour is therefore paramount for heavy-vehicle manufacturers to understand and thus make well balanced decisions to fulfill environmental goals.

A nonlinear centrifugal pendulum vibration absorber (CPVA) with normal-force dependant friction loss is investigated in a torsional model of a downspeeded powertrain of a heavy-truck. The engine model includes gas-pressure excitation and the existing pendulum model is extended to include a continuous formulation of end-stops at the end of the pendulum-path. Furthermore, the friction loss of the pendulum is experimentally determined. A pendulum-path parameter-study in the complete powertrain model is conducted to consider the effects of the system dynamics on the CPVA. It is shown that the performance of the CPVA is affected by the powertrain system-dynamics and thus important to consider in the design of the CPVA. Downspeeding of the engine by appropriate gearing of the driveline is a measure to decrease the CO2 emissions. However, downspeeding increases the torsional vibration and noise of the powertrain with conventional torsional vibration reduction methods. The CPVA can be used to reduce the torsional vibration and thus facilitate to reach environmental goals.

A flywheel mounted centrifugal pendulum absorber (CPVA) is designed to completely suppress the lowfrequency shuffle-mode resonance of a heavy-duty truck powertrain by exploiting the eigenfrequency veeringproperty of the CPVA. The shuffle-mode is excited by the half-order torque of a five-cylinder-engine ina downspeeded powertrain during cruising conditions. It is shown that the design of the CPVA may beperformed by linear analysis of the CPVA and powertrain system. The linear design is then validated by fullnonlinear simulations of the powertrain. A complete suppression of the shuffle-mode resonance is achievedwith relatively small total mass of the pendula which makes it highly possible to implement in practice.Downspeeding and downsizing of combustion engines, without sacrificing the power output, are methods toreduce emissions, although, resulting in increased noise and vibration using conventional vibration reductiontechnology. The CPVA is an order tuned device that can help to reduce the increased vibrations and thushelp to reduce the environmental impact of heavy-duty vehicles.