Rotational spring material definition

[Hidemasa KAIHARA]

Hi,

I have a question.
Generally, the performance of rotational spring gives Moment-angle relation.
According to the Command manual (page 127), stress-strain or force-deformation must be used in "uniaxialMaterial ElasticPP".
There is a problem in the case of definition of tha material of Rotational spring.
Although I verified Moment-angle relation can be used.
I mean, stiffness of rotation(Nmm/rad) as $E instead of modulus of elastic(N/mm2).
Above is no problem.

I want to use "uniaxialMaterial SAWS" as rotational spring. But I can't understand how to define this material.
This material is defined force-displacement relation according to the internet source. In the case of rotational spring, I must give parameters in M-θ.
I try several case.
For example, I give the angle at ultimate as $DU instead of the displacement at ultimate load.
Other parameters also give in the M-θ　field.

But the result of the analysis and M-θ behavior I assumed does not match.
(Upside down "T" shape model with one rotational spring at 2 element, and apply cyclic load. It is able to test rot spring, I think.)

I can't understand this reason. Because I try the same way in 2case (elasticPP and SAWS),although one is sucssess and the other is not.

If you know how to define SAWS material as rotational spring or rot spring material definition, teach me please.

Thank you for reading.

[vesna]

I'm not sure I understood you completely but I will try to respond to your question.

SAWS Material is developed to model wood shear wall and that is why in the manual it is described by force-displacement relationship. However, you can use this material to define moment-rotation relationship as well. Just replace all force input parameters with moment and displacement parameters with rotation.

[Hidemasa KAIHARA]

Dear Vesna

Thank you for your reply.
I understood the behavior of SAWS. Because it is very basic behavior of timber structure.

I could make rotational spring with SAWS thanks to your reply.
In case of additional problem is occur, I hope your teaching.

ありがとうございました

[yfeng]

Hi Hidemasa,
I am working on rotational spring, too. The element I used is zerolength element. Are you using this element also?

Thanks.

Yuhao

Hidemasa KAIHARA wrote:
> Hi,
>
> I have a question.
> Generally, the performance of rotational spring gives Moment-angle
> relation.
> According to the Command manual (page 127), stress-strain or
> force-deformation must be used in "uniaxialMaterial ElasticPP".
> There is a problem in the case of definition of tha material of Rotational
> spring.
> Although I verified Moment-angle relation can be used.
> I mean, stiffness of rotation(Nmm/rad) as $E instead of modulus of
> elastic(N/mm2).
> Above is no problem.
>
> I want to use "uniaxialMaterial SAWS" as rotational spring. But I
> can't understand how to define this material.
> This material is defined force-displacement relation according to the
> internet source. In the case of rotational spring, I must give parameters
> in M-θ.
> I try several case.
> For example, I give the angle at ultimate as $DU instead of the
> displacement at ultimate load.
> Other parameters also give in the M-θ　field.
>
> But the result of the analysis and M-θ behavior I assumed does not match.
> (Upside down "T" shape model with one rotational spring at 2
> element, and apply cyclic load. It is able to test rot spring, I think.)
>
> I can't understand this reason. Because I try the same way in 2case
> (elasticPP and SAWS),although one is sucssess and the other is not.
>
> If you know how to define SAWS material as rotational spring or rot spring
> material definition, teach me please.
>
> Thank you for reading.