Crank train torsional vibration is an important aspect for design and development of Powertrain for NVH refinement and durability. Crank train torsional vibration parameters like angular acceleration of flywheel or twist, depends upon various design parameters like geometry of crankshaft, mass of flywheel, stiffness of clutch, mass of pulley etc. It also depends upon engine operating conditions like engine speed, engine load, combustion peak pressure and combustion pressure variation etc.
Most of these parameters are decided by engine power, torque, engine architecture and packaging constraints. Addition of torsional vibration damper (TVD), which works on the principle of tuned dynamic absorber, is commonly deployed design solution to control the torsional vibrations as well as stresses (to improve durability of crank train) induced in crank train assembly at specified modal frequency.
This paper is critique study, which emphasizes on importance of accurate tuning of TVD frequency to make it work for NVH & durability improvement rather than deterioration. It also emphasizes whether crank train really need TVD or not. As its principle of working calls for, it needs to be tuned at right frequency to reduce the torsional vibration peak/twist at particular frequency. Any deviation in tuning of TVD frequency will force it to act as additional mass rather than tuned absorber. This will lead to the lowering of torsional frequency of crank train assembly and can shift the crank train assembly mode to critical operating frequency range of engine.