Horizontal force on glued surfaces

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Discussion Overview

The discussion revolves around the tensile testing of glued rubber surfaces, specifically focusing on converting a force measurement from kilograms to megapascals (MPa) to determine the maximum tensile strength of the glue. The context includes considerations of force orientation and the effects of material deformation under load.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Experimental/applied

Main Points Raised

  • One participant calculates the force from a mass of 2000 kg to be 19600 Newtons, emphasizing the need to find the area of the glue patch to determine pressure in pascals.
  • Another participant clarifies that pulling the patch away from the sheet indicates tensile strength, while pulling along the sheet indicates shear strength, highlighting the importance of the load orientation.
  • A participant questions whether it is correct to multiply the mass by 9.8 to convert to force, confirming that this is the acceleration due to gravity.
  • One participant notes that the force measurement is independent of orientation, but emphasizes the need for clarity on the test piece's orientation to distinguish between shear and tensile forces.
  • A later reply suggests that the rubber sheet may experience both tension and shear loads due to deformation under the horizontal load.

Areas of Agreement / Disagreement

Participants generally agree on the method of converting mass to force and the definitions of tensile and shear strength. However, there is uncertainty regarding the orientation of the test and the implications of material deformation, indicating that multiple views remain on the nature of the forces acting on the assembly.

Contextual Notes

There are unresolved aspects regarding the specific orientation of the test piece and how it affects the interpretation of tensile versus shear strength. Additionally, the potential for combined tension and shear loads due to deformation is noted but not fully explored.

Hubert96
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I am conducting tensile test on a bigger scale. When the material breaks i have the maximum kilograms that can be a applied to the material. I pull horizontal in a rubber patches glued to a rubber sheet and i want to find the maximum tensile strength in the glue. How do i convert my 2000 kg pull to MPa if the pull is done horizontal?
 
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Welcome to PF.
A weight of 2000 kg represents a force of F = 2000 * 9.8 = 19600 Newton.
Find the area of the glue patch, a, in m².
The pressure is then; F / a pascal.
1 MPa = 1 000 000. Pa

If you are pulling the patch away from the sheet it is tensile strength.
If you are pulling the patch along the sheet it is shear strength.
Take care that the flexibility of the sheet does not permit a tear to propagate, like peeling a label from a surface. In that case a lower force is needed because the area is reduced to a line.
 
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Thank you for the answer, very helpful. :)
 
one more thing. Since the pull directions is horizontal is it then correct to multiply the kg with 9,8. I assume that is the acceleration due to the gravity?
 
Force = mass * acceleration.
A mass on Earth generates a force of; F = m·g
The scales you measure the force of 2000 kg with, were calibrated to read mass on the Earth's surface. Your force of 2000 kg is multiplied by 9.8 to convert it to force in Newtons. That is independent of orientation.

I assume your rubber sheet is also horizontal and you are measuring shear. You have not clearly specified the orientation of your test piece, which is why I explained the difference between shear and tensile forces.
 
Hubert96 said:
I pull horizontal in a rubber patches glued to a rubber sheet and i want to find the maximum tensile strength in the glue. How do i convert my 2000 kg pull
Wow, you have a rubber sheet that is withstanding a 2000kg (2kN? 19.6kN?) pull? Can you post a picture of the setup?
 
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Since patch and sheet will tend to deform under that horizontal load, you may have a combination of tension and shear loads acting simultaneously on the assembly.
 
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