Support – Questions & Answers

Answer:

A very good way to investigate the dynamic properties of drive systems is to combine measure­ment results from field tests or proto­type investigations with a computational investigation and a detailed vibration analysis (torsional and lateral / flexural vibrations) supported by practical computer models.

Measurements usually only provide an instantaneous recording at specific measure­ment locations. Using computer models and suitable simulation methods, dynamic properties can be better explained and understood. Optimization measures can thus be developed in a more targeted manner.

In this respect, I always tend towards a „COMBINED MEASUREMENT + CALCULATION“ approach.

Especially in the context of the develop­ment and design process, computational investi­gations are absolutely necessary, since measure­ments are not yet available at this point in time.

Answer:

YES, I always recommend to explicitly plan the computational vibration analysis (simulation) especially in the context of new develop­ments or variant designs; and also independent of whether such an investigation is mandatory (as e.g. in the case of standards and guidelines).

Detailed calculations and analyses with modern simulation methods are always an integral part of the develop­ment and design of new machines (or optimization of existing machines) as part of a higher-level „VIRTUAL ENGINEERING„. This way you will not be surprised by vibration problems or other dynamic effects (like NVH effects) in the future.

I have many years of experience in generating practice-oriented vibration models, even if measure­ment data are not available at this point. Practical relevance therefore exists.

Answer:

The vibration calculations I offer, including the necessary analyses, usually comprise four (4) processing steps:

1. Generation of a practical vibration model (calculation model) depending on the specific task (i.e. rotor dynamic investigation and/or torsional vibration calculation)
2. Excitability analysis (determination of natural frequencies and/or critical speeds as well as the corresponding natural modes) and interpretation of possible resonance points in the resonance diagram (Campbell diagram)
3. Simulation (either „steady-state“ also in larger speed intervals or purely „time-dependent“); compilation of the results (graphical or tabular)
4. Interpretation of the results (if necessary also in comparison with measurements)
   – optionally as additional service: further parameter studies and elaboration of possible improvement measures
   – if necessary: model refinement or model extension and repetition of the above-mentioned work steps (iterative process)

Answer:

This is indeed a very good hint. Since machine monitoring is very often used in larger plants (such as chemical or cement plants, plants with reciprocating compressors or pumps, etc.), it is even more important to know which locations in the plant actually need to be monitored in terms of vibration in order to infer the condition at ALL important positions in the plant. For example, torsional vibrations at a coupling can be measured in terms of torque, but this may not be able to provide a direct indication of backlash at a gear stage or in a cardan shaft.

Thus, a computer model can be very helpful to perform a computational investigation on this basis in order to determine the system responses at all essential positions of the driveline – even where no measurements are or can be made.

By the way: With a suitable calculation model, measurements can also be planned better and more precisely as part of the predictive maintenance project.

So the answer to this question is a clear YES !

Answer:

YES, that’s exactly how it is. Systematic vibration calculations are very helpful for the purpose of identifying and interpreting vibration problems and especially damage cases. This includes resonance investigations, but also the existence of excessive system excitations which, depending on frequency position and amplitude, lead to unacceptably high responses (e.g. torques or bearing forces) in the drive system.

However, a comparison with measurements is crucial in such a case. The computer model may have to be adapted and refined to the practical conditions in a further analysis step, so that an iterative detailed analysis is required. For this purpose, experience in this field is indispensable.

In any case, vibration calculations within the scope of damage analyses are target-oriented, which is also clearly noticeable in a minimization of processing time and costs.

Answer:

Unfortunately NO. Simulation models are as good as the data basis is as well as the reliability (and validity) of all parameters. However, depending on the task, there are also data uncertainties (e.g. in the actual dampings), so that a calculation cannot replace a measurement across the board.

A calculation can complement a measurement and vice versa. Only in the case of development and design, the calculation must first do without parallel measurement. The verification of the calculation model then takes place later during the first commissioning. Maybe you can consider earlier measure­ments from existing, similar, and above all comparable rotating machinery.

As already said above: I always recommend the combination of measurement and calculation. Both methods must not be played off against each other.

Answer:

There are many ways to provide a suitable engineering service from my side. Usually I receive a task from the customer (problem description, compilation of requirements) possibly together with an overview sketch of the drive system and – if available – also with results of already existing measure­ments and calcu­lations. On this basis, you will receive an offer from me for a computational vibration analysis on a fixed-price basis.

In exceptional cases – e.g. in case of an unclear task or in case of pure consulting activities – I also offer my services on a variable basis according to charging rates.

And I would like to answer the additional question regarding the fun­da­men­tal advantages of an in­de­pen­dent engi­neering service provider as follows:

1. As an independent service provider, I can adopt a completely neutral position towards my customers (OEMs but also typical supplier com­panies such as coupling, clutch, gearbox or other com­po­nent manu­facturers). This simplifies the cooperation with all parties involved enormously and also offers the possibility to deal with the topics in a more detailed and more functional way.

2. Independence and neutrality also mean that calculations do not necessarily have to refer to specific supplier products. Often (minimized) calculations are also offered by suppliers themselves, even though they are not completely responsible for building the end product (i.e. the complete machine). This results in conflicts of interest that do not even arise with an independent service provider.

3. It must also be noted that a compu­tational analysis triggered by a component supplier is generally not possible (not least for capacity and compe­tence reasons) in terms of the complete­ness and detail of the analysis. In this case, it would always make more sense for the actual machine manu­facturer (OEM) to employ an independent service pro­vider directly. The OEM can then also examine, evaluate and opti­mize its own product on its own respon­si­bility. This approach is also preferred by the end customer and also helps to generate the manu­facturer’s own know-how. In each case, based on numerous expe­riences, I advocate suitable cooperation between all partners involved – including the in­de­pendent engi­neering service pro­vider.

Answer:

I specialize in computational studies (simulations) of vibrations in drive systems (drivelines) such as in all rotating machinery, but also in vehicles, ships, etc.

This includes:

1. TVA = Torsional Vibration Analysis (torsional vibration analyses)

2. LVA = Lateral Vibration Analysis (analysis of transverse vibrations with bearing influence)

3. RDA = Rotor Dynamic Analysis (complete analysis incl. detailed journal bearing models)

The analyses are carried out using commercial software (such as ARMD) but also including my own software tools.

Reports are prepared either in German or English. Optionally, I also present results in the context of customer-specific online meetings.

Answer:

The provision of data by the customer can indeed be cumbersome, as one is also dependent on the cooperation of suppliers. I offer my customers assistance in the form of a guide that summarizes the most important information on data procurement depending on the calculation model.

If necessary, I can also actively engage in dialog with suppliers at the customer’s request.

Answer:

YES, I also offer an „express service“ in the context of emergencies (damage cases); i.e. particularly fast (but still careful) computational vibration analysis for the purpose of determining the (main) cause of the vibration problem as well as also an initial presentation of possible problem solutions.

The decisive factor in typical „troubleshooting“ actions is always the solution finding (i.e. root cause analysis and not a pure analysis of „symptoms“).

Answer:

Depending on the customer specification, I can also offer extended services through my partner network, both measurement services and extensive structural analyses (FEM). Depending on the customer’s requirements, I can then present and comment on the results in summary form in close coordination with my partners.

Answer:

YES, especially in the case of detailed analyses of bearing arrangements (fluid-film bearings or rolling bearings), additional calculations can be offered based on special, detailed bearing models. This plays an important role especially for drives with higher speeds.

Here I work particularly closely with my US partner Concepts NREC.

Answer:

According to my GTC (general terms and conditions), there is a mutual obligation regarding confidentiality in every case. This is a matter of course for me for a close and trustful customer cooperation.

By the way: There is also such a confidentiality obligation between my US partner Concepts NREC and me.

Optionally, the customer can also send me his own wording on the subject of non-disclosure agreement (NDA) for review in advance.

Answer:

I work internationally and serve the following regions in particular:

Europe, but also: Africa, Near/Middle East.

As a contractual partner of the US company Concepts NREC I also officially represent Concepts NREC’s engineering services and the associated software products (ARMD) in these regions.

Answer:

You can reserve a no-obligation, no-cost initial consultation appointment at any time via my contact page. To do so, follow the CONTACT link. I look forward to your inquiry.

Answer:

Under PUBLICATIONS the sources of interesting publications, technical papers, and conference papers are summarized.

Answer:

YES, I already recoemmend (since 2004) the ROTOR DYNAMICS SEMINAR in close cooperation with my US partner Concepts NREC in form of an international technical event (either in-person or online). Further information on the seminar program, dates and registration (incl. costs) can be found under SEMINARS.

In addition, short webinars are also offered free of charge. Topics and registration: see WEBINARS.

Answer:

As an official distribution partner of the US company Concepts NREC I offer the modular software package ARMD in different license models.

If desired, you can also book a free software online presentation; please contact me in advance, as these dates will be arranged together with Concepts NREC.

Optionally, in addition to the software license, professional support including software maintenance (if necessary with additional customer-specific training) is also offered.

Further information under ROTOR DYNAMICS & ARMD Software.