Elastic deformation of a jar lid (continuüm mechanics)

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SUMMARY

The forum discussion focuses on calculating the necessary pressure for a food packing company to ensure that jar lids snap inside after packing. The challenge arises from the complexity of analyzing a thin-walled shell, as opposed to simpler beam constructions. Participants attempted to apply the theorem for thin-walled conical shells but encountered difficulties due to assumptions of indeformability in the horizontal sections. Suggestions for alternative approaches, including exploring snap-through buckling, were proposed to address the unique geometry of the jar lid.

PREREQUISITES
  • Understanding of continuum mechanics principles
  • Familiarity with thin-walled shell theory
  • Knowledge of snap-through buckling phenomena
  • Basic skills in mathematical modeling and pressure calculations
NEXT STEPS
  • Research the application of thin-walled shell theory in practical scenarios
  • Explore the mathematical derivation of snap-through buckling
  • Investigate alternative theorems applicable to large angle geometries
  • Learn about computational methods for simulating pressure effects on shell structures
USEFUL FOR

Mechanical engineers, packaging designers, and anyone involved in the design and analysis of food packaging systems will benefit from this discussion.

Hubabuh
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For a day and a half now we have been trying to calculate a self-assigned problem. However, this has not turned out to be easy and build-up frustration has lead us to this forum. Our challenge was to calculate what under pressure a food packing company needs in it's jars to make sure the lid snaps inside after packing.

Schematically represented is the intersection in the following figure:
1ZrmM.png


This is not a difficult exercise if this was just a beam construction. This is however a difficult exercise if it is a thin walled shell revolted around it's center.

We tried it by using a theorem for thin walled conical shells, but this is not only a very difficult theorem, it also assumes the upper and lower horizontal part to be indeformable; something our feeling says to not be neglect-able.

We assume to be able to find a formula for the vertical movement of the middle as a function of the applied (under) pressure. Does anybody have any suggestions? Can we maybe use a different theorem since our angle "a" is very large?
 
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