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Tensile Creep Tests

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Posts: 22
Topic starter
(@Giorgio)
Eminent Member
Joined: 8 years ago

Hello guys,

I want to do some test using [B]tensile creep tests [/B]in order to evaluate Viscoelastic behaviour of such a Paperboard materials. In this case, I want to apply a constant tensile load of [B]&#963,[SUB]0[/SUB][/B] at a very short Instantaneous time of [B]t1[/B]. Then the sample is kept under the constant load for a longer time of [B]t2[/B]. The yield stress of the material is [B]&#963,[SUB]Y[/SUB][/B].

I have two clear questions as below:

1- Is there any special relationship between [B]&#963,[SUB]0[/SUB][/B] and the value of [B]&#963,[SUB]Y[/SUB][/B]? May you please provide ma by some reference or Standard specification for this concept?

2- How much time would be enough for [B]t1[/B] and [B]t2[/B]. ? Is there any special Standard for that as well?

Many thanks for your consideration and hope to meet your reply.

Greetings,

Hassan

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4 Replies
Posts: 3998
(@jorgen)
Member
Joined: 5 years ago

There are no hard rules. Here are some ideas:
* I typically pick sigma_0 < sigma_y
* I typically pick t1 about 1 sec, t2 a few hours

-Jorgen

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Posts: 5
(@HAN8810693)
Active Member
Joined: 8 years ago

Many thanks Jorgen,

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Posts: 1
(@Enghalab)
New Member
Joined: 6 years ago

Hello Jorgen Sir

I am also modeling tensile creep behaviour in ABAQUS to validate experimental data. Please help me in following points

1. How to get prony parameters. I am specifying viscoelastic material properties (Hyperelastic for Elastic part and viscoelastic for viscous part). Hyperelastic part is ok but when i want to obtain prony coefficients by giving creep test data in shear (because i dont have shear creep data), it is showing error message as NO CONVERGENCE FOR ANY ORDER N FOR THE VISCOELASTIC SHEAR TEST DATA. Please help me in this issue.
2. When it comes to provide steps and loading, can you please guide me what inputs should i give. My test conditions are 150 seconds of loading at 5 MPa then recovery for 900 seconds.

Thanks in advance
vivek

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Posts: 3998
(@jorgen)
Member
Joined: 5 years ago

1. I suggest performing stress relaxation experiments and then fitting the Prony series using MCalibration.
2. I you pick a small max time step of about 5.

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