Typical dynamic loads generated by dynamometer, driveshaft, and vehicle engine

[JMGraham]

I am designing several foundations to support dynamometers connected to vehicle engines by driveshafts. The purpose of my analysis is to minimize the vibrations transmitted to nearby sensitive equipment. My client has not provided the dynamic loads generated by the dynos, driveshafts and engines. Are there typical values for these parameters that could be used when this information is not supplied?

 

[SwinnyGG]

If you're actually going to calculate specific elements of the design, you need to obtain this information from your customer. The range of excitation energies/amplitudes/frequencies that can be produced by an ICE engine of unknown size and configuration is huge.

 

[JMGraham]

Okay thanks. That's useful information for me.

 

[GregLocock]

For instance an I4 engine will easily produce 20g at its engine mounts, whereas an I6 will reach about 5g.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?

 

[dgallup]

Our dyno cells have large concrete and steel plates in the floor that are supported on springs vertically and horisontally (I don't know if there are dampers or not) to minimize vibration transmission. The engines and dynos are both mounted to the plate and connected by driveshafts. I've never seen this done anyplace else but it's quite effective. When I worked for a class 8 truck engine manufacturer, the dynos were bolted directly to the concrete floor and the engines were on adjustable stands so they could be precisely aligned to the dyno and a flexible coupling was used between them. You could feel the vibrations hundreds of feet away.

----------------------------------------

The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.

 

[GregLocock]

You should check out engine noise test cells. They use seismic blocks as dgalup describes, say 20_200 tonnes of concrete on rubber pads.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?

 

[3DDave]

I wonder how they plan to prevent the engine vibrations from shaking the vehicles they will be placed in and how sensitive the other equipment is to vibration. A lot of sensitive equipment goes onto isolation platforms.

 

[JMGraham]

Thanks for the responses everyone. I have been given the maximum torque of the engines. If I multiply that by the square of the radial frequency (i.e. max torqure x (2 pi (max rpm/60))^2) will that give me the dynamic force?

 

[GregLocock]

No.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?

 

[LionelHutz]

I believe 3DDave's comment on isolation platforms is saying it is easier to isolate the sensitive equipment then mitigate the engine vibrations into the surrounding structure. I would tend to agree.

Otherwise, some kind of isolation spring supporting and isolating a very heavy block is the way to go.

 

[JMGraham]

Thanks. They have an electron microscope with very low vibration criteria (VC-E) but it's almost 500 ft away. They dyno's and engines need to be supported on foundations with piles extending to bedrock for geotechnical reasons so the client is hoping that the foundation design and distance will be enough to attenuate the vibration. The electron microscope is already in use so I'm guessing it would be difficult to install an isolation platform now but we can suggest that if they end up exceeding the criteria.

 

[GregLocock]

Isolate the engine and dyno using a seismic block. Job done.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?

 

[gruntguru]

We have engine dynos on the ground floor of our seven story building. Noise complaints from offices on several floors were cured by inserting a few small chocolate blocks of rubber (look like waffles) between each concrete plinth (several tonnes each) and the concrete floor. Link

je suis charlie