--- title: "Torsional Vibrations" description: "Torsional Vibrations. Torsional Vibrations in Rotating Machinery, Cars + Trucks, Ships.   Basics. The engineering jobs contain calcu~lations and simula~tions of TOR~SIONAL VIBRA~TIONS of straight, branched, and inter~mesh~ed drive sys~tems (drive~lines, power~trains) also con~sider~ing non~linear cha~rac~teristics (e.g. rubber coup~lings, gear stages with" url: https://www.laschet.com/en/engineering/torsional-vibrations/ date: 2017-02-13 modified: 2026-06-24 author: "Dr. Andreas Laschet" type: page lang: de-DE --- # Torsional Vibrations # Torsional Vibrations ## Torsional Vibrations in Rotating Machinery, Cars + Trucks, Ships ![Compressor Driveline / (c) RBTS](https://dev.laschet.com/wp-content/uploads/Compressor-Driveline-1024x476.jpg) ### Basics The engineering jobs contain calcu~lations and simula~tions of **TOR~SIONAL VIBRA~TIONS** of straight, branched, and inter~mesh~ed **drive sys~tems** (drive~lines, power~trains) also con~sider~ing non~linear cha~rac~teristics (e.g. rubber coup~lings, gear stages with back~lash, shift and en~gage effects in clutches, etc.) in the time or fre~quen~cy do~main. We can follow steady-~state condi~tions or time-~tran~sient effects in the si~mu~lation en~viron~ment. Further~more, con~trol effects may be part of an ex~panded tor~sional vibra~tion mo~del. The CAE results show the **natural fre~quencies** **(critical speeds)** usual~ly pre~sented in so-called **„Campbell“ dia~grams (inter~ference dia~grams, water~fall dia~grams)**, as well as the gra~phi~cal inter~pre~tation of the **vibra~tion modes (modular forms, mode shapes)**. We also get simu~la~tion re~sults showing the ex~pected ampli~tudes and magni~tudes (usually taken from **torque signals**, **velo~cities** and **speeds**, **accelera~tions**) depend~ing on the exist~ing excita~tions (i.e. **excita~tion torques** of the motor, the engine, the work~ing process, and the operat~ing con~ditions). ### Procedure ### ![Drive of a Cement Mill with Planetary Gear / (c) Laschet Consulting](/wp-content/uploads/Planetengetriebe-01-SMALL-150x150.jpg) A typical torsional vibration analysis (TVA) is structured as follows: - **MODEL GENERATION **creating the computer model according to the technical require~ments consi~dering all relevant drive elements and excitation sources - **ANALYSIS OF EXCITABILITY **calcu~la~tion and inter~pretation of the natu~ral be~havior in~cluding reso~nance ana~ly~sis depend~ing on the sys~tem exci~ta~tion (studying inter~ference dia~grams), first mo~del vali~da~tion [https://dev.laschet.com/wp-content/uploads/TORSION-ModeShapeAnimation-01.mp4](https://dev.laschet.com/wp-content/uploads/TORSION-ModeShapeAnimation-01.mp4) ###### *Source: RBTS, Inc. / USA (Software: ARMD)* - **SIMULATION **determination of the system response like torques in the shafts, couplings, gear stages, etc. – either time dependent or speed dependent - **POSTPROCESSING + INTERPRETATION **analysis of the results compared to measure~ments and expe~riences, final mo~del vali~da~tion and model refine~ment (if necessary) - *OPTION:*** FURTHER CASE STUDIES, SYSTEM OPTIMIZATION **specification of a technically and economically reasonable „best“ drive system configuration ### Simulation Methods We distin~guish between two different simu~la~tion methods for the CAE analysis: a) the „**STEADY-STATE SIMULATION**“ (i.e. the simu~lation of the steady-~state operat~ing con~dition with con~stant operat~ing speed also known as „simulation in the frequency domain“) b) the „**TIME-TRANSIENT SIMULATION**“ (i.e. the „simu~la~tion in the time domain“ to deter~mine the time-~transient response of the drive system depend~ing on time-variable operat~ing con~ditions also consider~ing non~linear effects like gear back~lash) ![Simulation of a Compressor Drive System / (c) RBTS](/wp-content/uploads/ARMD-Ergebnis-05.png) Possible resonances can be pre~destinat~ed („simu~lat~ed“) – simi~lar to a „wea~ther fore~cast“ of the dyna~mic beha~vior of the com~plete drive sys~tem (drive~line, power~train); here: example of a reci~pro~cating com~pressor drive~line. ###### *Source: RBTS, Inc. / USA (Software: ARMD)* ### Special Analysis, NVH Studies ![Measurements compared with CAE Analyses](/wp-content/uploads/Messergebnisse-Frequenz-01.jpg) Even dynamic-~acoustic effects can be pre~dict~ed as part of so-called **NVH studies** (NVH = „**N**oise, **V**ibra~tion, **H**arsh~ness“) which are im~por~tant when **opti~miz~ing auto~motive drive~lines and com~plete power~trains** (cars, trucks, any other vehicles). Spe~cial re~ferences and ex~tend~ed in~for~ma~tion par~ticular~ly on this sub~ject are available on re~quest. ###### ![Applying CAE Tools: Simulation Models of Complete Drive Systems](/wp-content/uploads/SimX-Modell-05.jpg)*Source: ESI-ITI, Dresden / Germany (Software: SimulationX)* I would like to offer my best **custom-tailored engineering service** concerning your current project. Please send me your inquiry ([submission of your inquiry](https://dev.laschet.com/en/contact/)). I also offer **customized training courses**. More detailed infor~ma~tion concern~ing all the other sub~jects are available as well. Please [contact me](/en/contact/). ## Further Information on Special Sites Please visit the following special sites for more detailed information ... ### [Rotordynamics, Lateral + Flexural Vibrations](/en/engineering/rotordynamics/) *Analysis especially of lateral and flexural vibrations including a stability analysis of rotor bearing systems in rotating machinery supported by the software ARMD. [Learn more …](/en/engineering/rotordynamics/)* --- ### [Virtual Engineering, Development, Simulation](/en/engineering/virtual-engineering/) *The virtual development process requires suitable R&D software tools, simulation environment, measurements, field tests, experiences. [Learn more …](/en/engineering/virtual-engineering/)* --- ### [Technical Papers, Publications, Conferences](/en/engineering/publications/) *Publications by Dr. Andreas Laschet: technical papers in journals, conference papers, book contributions. 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