Fracture setup of elastic sample between rigid beams

Posted Apr 15, 2024, 6:27 a.m. EDT Results & Visualization, Studies & Solvers, Structural Mechanics Version 6.1 2 Replies

Hendrik Ostrowski

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Hi,

I'm currently trying to build a structural fracture mechanics analysis, but am stuck on the very beginning of the setup. I want to have an elastic sample clamped into two pairs of beams, one on either side. The beams are connected to each other with a hinge plate (allowing for rotation, but locking vertical deisplacement) and loaded with outward directed forces, so that the whole setup is symmetrical along the mid plane of the sample.

I want the sample to be elastic with prescribed material properties and the beam to be rigid. Ideally, I want a plot of the applied load over the maximum displacement (so the deflection at the load initiation point, x=0).

Problem is, I cannot assign a prescribed displacement to the point symbolizing the hinge connection, I assume that is due to the assignment of the beam as rigid. Furthermore, I am unsure about how to vary the load in order to get a new displacement value for each increment.

I'd be grateful for any kind of help!!

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demo.mph

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2 Replies Last Post Apr 17, 2024, 9:05 a.m. EDT

Hans Christian Christiansen COMSOL Employee

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Posted: 2 weeks ago

Hi Hendrik,

When working with rigid material on a domain, you can control the displacement and rotation of that domain by adding a Prescribed Displacement/Rotation as a subnode to the Rigid Material. In the Settings for this node you should be able to change the Center of Rotation to Centroid of Selected Entities and then change the Entity level to Point and choose the relevant point in the subnode Center of Rotation: Point 1. By also setting the prescribed displacement in the node you should be able to achieve the rotation you are looking for.

With regards to the load increment you can use the method used in bracket_parametric from https://www.comsol.com/model/bracket-8212-structural-mechanics-tutorials-10314

In general I can recommend running through the Bracket tutorials as they provide a good introduction to many of the methods and analysis types in structural mechanics.

Best Regards Hans Christian

Hendrik Ostrowski

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Posted: 2 weeks ago

Thank you Hans, with your tip I could define the center of rotation for the beam! But I have now decided to take a different approach: I want to try to model it with decohesion (like in this tutorial). But I am encountering one big problem: I don't know how to prescribe the displacement in the load point that drives the simulation, because I can only add prescribed displacement to the rigid domain once, which is used to define the center of rotation. Can I define the hinge point as center of rotation and additionally prescribe a displacement in the load point?

Best regards, Hendrik Ostrowski

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Screenshot.png

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