what is the difference between compliance and weighted compliance?

Sreekanth

Adriano Koga_20259

There are a few topics around here about this.

https://community.altair.com/community?id=community_search&spa=1&q=weighted compliance&t=&order=score&orderDesc=true

Also if you take a look at OptiStruct documentation, under REsponses you would find the formulation of both of them.

 

Anyway:

1- Compliance is the sum of strain energy of your model, meaning the higher the value, more your model is deforming under the same load. This essentially gives you an inverse measure of stiffness, and that's why we tipically use a formulation of minimize Compliance for topology optimization, seeking for the stiffest structure.

Another way of calculating compliance, under a fixed load, is basically:

C = SUM (forces * displacements) 

if the load F is constant, the higher compliance, means higher displacements.

Compliance is calculated for ONLY 1 Loadcase.

 

2 - Weighted Compliance is just a combination of Compliance values for multiple loadcases.

So, WCOMP = Sum(wi * Ci)

wi is a weight scale factor

Ci is the compliance of each loacase 'i'

So, if you have 10 static loadcases in your model, you can combine them using WCOMP.

the weight is optional, and by default 1.0 for all.

But you could use the weightning factor to balance the numeric effect of each loadcase, as typically some loadcases have displacement(thus Comp) higher than others.

If you don't balance them by using weighting factors, one loadcase can overcome all others, and drive the optimization all by itself.

Adriano Koga_20259

There are a few topics around here about this.

https://community.altair.com/community?id=community_search&spa=1&q=weighted compliance&t=&order=score&orderDesc=true

Also if you take a look at OptiStruct documentation, under REsponses you would find the formulation of both of them.

 

Anyway:

1- Compliance is the sum of strain energy of your model, meaning the higher the value, more your model is deforming under the same load. This essentially gives you an inverse measure of stiffness, and that's why we tipically use a formulation of minimize Compliance for topology optimization, seeking for the stiffest structure.

Another way of calculating compliance, under a fixed load, is basically:

C = SUM (forces * displacements) 

if the load F is constant, the higher compliance, means higher displacements.

Compliance is calculated for ONLY 1 Loadcase.

 

2 - Weighted Compliance is just a combination of Compliance values for multiple loadcases.

So, WCOMP = Sum(wi * Ci)

wi is a weight scale factor

Ci is the compliance of each loacase 'i'

So, if you have 10 static loadcases in your model, you can combine them using WCOMP.

the weight is optional, and by default 1.0 for all.

But you could use the weightning factor to balance the numeric effect of each loadcase, as typically some loadcases have displacement(thus Comp) higher than others.

If you don't balance them by using weighting factors, one loadcase can overcome all others, and drive the optimization all by itself.

Sreekanth

Thank you so much for your reply, Now I understand the difference

Rahul_P1

Sreekanth said:

Thank you so much for your reply, Now I understand the difference

HI Sreekanth,

Please refer to the help documentation and OptiStruct user guide within the help which describe these concepts in detail

also see Free eBook: Practical Aspects of Structural Optimization with Altair OptiStruct