Torque data analysis from WTF

Question

Torque data analysis from WTF

pietro82 (Automotive)

(OP)

12 Oct 14 04:29

Hi all,

I work in a ground vehicle company as a road load data analyst and actually I have to work on the durability analysis of a vehicle transmission, thefore I'm analyzing torque data measured on the field on a vehicle. About this topic what I have done so far was to measure and analyze the torque at the flywheel with the engine speed and the engaged gear, computes the torque counts and damage. We have bought 6 wheel force transducers mainly for measuring the axles loads but they measure the wheel driving torques. I have just collected some data for the first time. Speaking about the torque driveline torque analysis, I don't know which additional information I may get from the driving torque signals from these sensors. Is there anyone who uses this sensors? Any suggestion is appreciated.

Thanks

Cheers

Pietro

FeX32 (Mechanical) · Answer 1 · 2014-10-12 10:58:42

We use torque transducers all the time in engine testing and development.
What kind of additional information are you looking for? Torque sensors are usually sophisticated strain gauges within a particularly designed housing to minimize nonlinearities.
Thus, usually other information is gathered with other sensors. Usually a few speed sensors (along with torque) are enough to understand what's going on.

pietro82 (Automotive) · Answer 2 · 2014-10-12 12:15:32

Hi FeX32,

maybe I haven't properly explained the kind of sensor I mean. Here a photo sample of the sensors:

http://www.michsci.com/Instrumentation/images/Whee...

What I usually do is: installing a strain gauge at the engine flywheel for measuring the flywheel torque and from it I compute the torque counting histogram and the damage. For durability analysis how may I use the flywheel torque signal together with wheel torque signal?

GregLocock (Automotive) · Answer 3 · 2014-10-12 18:44:11

The WFT helps you to determine the torque fluctuations downstream of the transmission, which may be filtered out before they hit the flywheel torque sensor by the transmission.

Cheers

Greg Locock

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pietro82 (Automotive) · Answer 4 · 2014-10-13 02:59:32

Hi Greg,

thanks for your reply. What may filter the torque at the flywheel? The damping in the system?

GregLocock (Automotive) · Answer 5 · 2014-10-13 03:41:40

Partly, also the torsional spring /inertia characteristics, compliances in the axle mounts etc

Cheers

Greg Locock

New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?

pietro82 (Automotive) · Answer 6 · 2014-10-13 09:02:04

Thanks Greg,

so the wheel torques is more relliable for durability analysis of transmissions than flywheel torque, right?

GregLocock (Automotive) · Answer 7 · 2014-10-13 18:14:29

No. I'd use both. Actually rather than WFT I'd prefer a strain gauge on the propshaft. Are you mainly concerned with transmission durability?

Cheers

Greg Locock

New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?

pietro82 (Automotive) · Answer 8 · 2014-10-14 11:21:58

Greg,

I am mainly interested in load analysis for transmission durability. A strain gauge on the propshaft is probably the best idea but I think it is a bit harder to install. How would you use both signals?

BrianE22 (Specifier/Regulator) · Answer 9 · 2014-10-14 12:29:41

It would be an interesting study to find out how much filtering is done by the mechanical springs and masses. You might find that the torques from the WFT are good enough for a durability study.

pietro82 (Automotive) · Answer 10 · 2014-10-14 15:46:56

Brian,

you would compare just the damage and the torque counting? In case I can do an analysis and show some results

pietro82 (Automotive) · Answer 11 · 2014-10-20 16:33:42

I have just done a simple analysis. Torque from WFT measure has a higher frequency bandwith but it doesn't measure the idling torque, so the torque is around 10% lower in steady conditions, but the transient response is well reproduced by the WTF sensors. So far I think the flywheel torque is better than WTF torque for durability analysis.

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Torque data analysis from WTF