Hasse & Wrede. Products.

The damper provides the necessary restoring torque by connecting the secondary inertia (ring) to the primary inertia (housing or hub) via the silicone oil. When relative oscillating motion between primary and secondary inertia occurs, the silicone oil in the gap is sheared. The occurring shear stresses depends both on the shear amplitude (equivalent to a mechanical stiffness) and the shear velocity (equivalent to a mechanical damping). Multiplying an infinitesimal area with the radius (distance to the rotational axis of the drivetrain) and integrating over the area results in the overall restoring torque.

The part of the shear stress which is proportional to the shear velocity is converted into heat and dissipated via the damper surface to the environment (damping). The amount of shear stress which is proportional to the shear amplitude generates a restoring torque in the silicone oil and does not dissipate energy (equivalent to a spring stiffness). An optimum damper tuning requires both damping and stiffness.

In case of constant rotation of the powertrain (no torsional vibrations), the primary and secondary inertia will rotate with uniform speed and consequently no relative motion and restoring torque occurs. Hence, the viscous torsional vibration damper does not damp the uniform rotation of the powertrain.

Unlike other torsional vibration damper concepts, viscous dampers operate completely independent from the machine’s lubricating oil circuit and do not require additional connections or higher oil pump power.

Hasse & Wrede’s advanced silicone fluid models and simulation routine consider both frequency-dependency and nonlinearity of silicone fluid under shear load. This enables highly precise performance prediction compared to industry standard simulation, including a-priori detection of unstable operating regimes.

Our 3D - Temperature field simulation and our latest generation of multi-factor silicone fluid lifetime models enable us to predict damper lifetime with much higher accuracy compared to industry benchmark. Specific load profile analysis can be carried out according to customer input data. If a detailed CFD simulation of the thermal environment is available, we support a full-3D finite-element damper thermal simulation and lifetime evaluation.

A finite-element based structural integrity simulation is a standard step in the development of a new damper design. Specific focus is on the fatigue simulation of the welded connections. Our telemetric measurement technology enables us to measure 6-DoF acceleration measurement on rotating shafts, which serves as input value to our finite element analysis.