How to extract load history if only displacement is measured? 1

[sftvbr]

Hello All

My aimm is to calculate the damage (life cycles) for some automotive part that I don't indicate the name here.

as far as I know many automotive RLDA tests give displacement sensors results , I am doubting if its possible to calculate and extract load histort or stress history to inrtoduce to the Fatigue calculation software.

my concern is : how valid is to consider the relation between load and displacement to use displacement PSD instead of load psd ?

 

[GregLocock]

That depends on what the component is. On some components measuring the displacement tells you what the load is. In others, not. If you have a full vehicle model and run it down the same road surfaces and you get the same displacements then if you trust the process (where i work we don't) then you can interrogate the model to get the loads.

Cheers

Greg Locock


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[btrueblood]

Greg,

Any chance you can elaborate? I've seen a few news reports, but from non-techy sources it's not clear what the issues were/are.

 

[GregLocock]

The easy one is the if you measure the suspension displacement history. You can differentiate that and hope to get the shock absorber force, and obviously you hope you can get the spring force, but if you put a load cell at the top of the strut you discover that your shock absorber model is not anything like sophisticated enough to predict the forces in a typical high velocity durability event.

And so on.

Cheers

Greg Locock


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[sftvbr]

All of this is possible ,if you are the OEM , otherwise, if you are a supplier, you don't have much data

 

[GregLocock]

So ask the customer. If you don't have enough information to run a durability test they need to supply it.

Cheers

Greg Locock


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[sftvbr]

Usually in Automotive, or they don't have or they don't give. The more you say you lack data, the worse it gets and makes the client escape like a frightened goose

 

[GregLocock]

Oh well. That's that then.

Cheers

Greg Locock


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