How does glue reinforce two sheets of paper joined together?

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    Bending Paper
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Discussion Overview

The discussion revolves around understanding how glue reinforces two sheets of paper when joined together, focusing on modeling the resistance to bending in this context. Participants explore both empirical and theoretical approaches to quantify the effects of glue on the rigidity and behavior of the combined sheets, considering various factors that influence their mechanical properties.

Discussion Character

  • Exploratory
  • Technical explanation
  • Mathematical reasoning

Main Points Raised

  • One participant expresses uncertainty about how to begin modeling the resistance to bending of two glued sheets of paper and seeks guidance on relevant formulas and methods.
  • Another participant suggests that if the glue is non-penetrating and the layer is thin, the rigidity is proportional to the square of the number of sheets bonded, while penetrating glue could increase rigidity by up to three times, depending on the type of glue used.
  • A participant emphasizes the need for more than just rigidity to simulate the behavior of glued sheets, indicating a desire for a comprehensive understanding of the physics and engineering principles involved.
  • It is noted that boundary conditions such as fixed, sliding, or free points should be established for simulations, and the moment-area method is proposed for calculating flexural loads, although it may not account for torsion or vibrations.

Areas of Agreement / Disagreement

Participants express various viewpoints on the modeling of glued sheets, with some agreeing on the importance of rigidity and boundary conditions, while others highlight the complexity of simulating the behavior of the sheets, indicating that multiple competing views remain on the best approach.

Contextual Notes

Participants mention limitations in their understanding of the necessary physics and engineering concepts for simulations, as well as the need for specific methodologies to accurately model the behavior of glued sheets under different conditions.

Phylosopher
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TL;DR
Take two sheets of paper, glue them together. How hard is it to bend the papers?
I am no engineer, just a physicist. I usually do not work with such problems, so I basically do not know what to look for to begin with.

My question/questions goes like this, take the following situation:

Fetch a paper, such single paper is easy to bend. If one takes glue, and glue this previous paper with another one. Obviously, the two papers are harder to bend.

  • How to model the "resistance" to bend of a simple two dimensional object? (Formulas, methods, coefficients etc...)
  • How does glue enforces the two sheets, and how to model its effect? (I am seeking empirical as well as theoretical formulas)

I am clueless on this subject and I do not really know where to look at! I surfed throw the following on wiki: Bending, Bending Moment.
 
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If glue is non-penetrating, and glue layer is thin, rigidity is simply proportional to the square of number of sheets bonded.
In case of penetrating glue, additional rigidity multiplier up to x3 may be applicable, depending on the sort of glue. Phenolic thermo-reactive adhesives are in particular formulated for high rigidity of bonded paper products (phenolic paper).
 
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trurle said:
If glue is non-penetrating, and glue layer is thin, rigidity is simply proportional to the square of number of sheets bonded.
In case of penetrating glue, additional rigidity multiplier up to x3 may be applicable, depending on the sort of glue. Phenolic thermo-reactive adhesives are in particular formulated for high rigidity of bonded paper products (phenolic paper).

Thanks.

Maybe I wrote my questions in a the wrong way! I am interested in simulating the behavior of the sheets after applying the glue. Just knowing the rigidity won't do it for me I guess!

Take this for example. Instead of a Beam, its a paper. What do I need to know to make such simulation? Rigidity and stiffness is one thing to look for, but what else?

The problem that I have is not that I don't have the knowledge of physics or programming etc... I just don't know what physics/engineering I need to start the simulation ^^"
 
Phylosopher said:
Take this for example. Instead of a Beam, its a paper. What do I need to know to make such simulation? Rigidity and stiffness is one thing to look for, but what else?
You should also set boundary conditions. Fixed point, sliding point or free point.
Regarding methodology, for static loads, simplest way may be to us moment-area method. You just treat each rectangular piece of paper part as beam. This method does not allow calculation of torsion modes of sheet or vibrations, but is sufficient for flexural loads response calculation. Shapes are typically hyperbolic functions after you integrate deflection along the sheet.
http://www.learnaboutstructures.com/Moment-Area-Theorems
 
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