Calculating Psi from Rectangular Box Experiment

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Discussion Overview

The discussion revolves around calculating the psi (pounds per square inch) of a material used in a rectangular box experiment that involved loading the box with weights until mechanical failure. Participants explore whether the psi can be accurately calculated based on the surface area and the nature of the failure, considering the geometry of the box and the method of weight application.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions if the psi can be calculated simply from the surface area of the box, suggesting that the geometry may affect the point of mechanical failure.
  • Another participant asks whether the experiment was designed to test the strength of the component or if the failure was incidental due to excessive weight.
  • A later reply emphasizes that calculating psi based solely on the surface area of the box is likely inaccurate, noting that the method depends on how the weight was applied and the nature of the failure.
  • It is suggested that if the box was loaded symmetrically, the walls would experience compression, and the psi could be calculated using the total weight divided by the cross-sectional area of the walls.
  • Participants inquire about the specifics of the failure and whether a 3-point flexural bending test is being considered.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the accuracy of calculating psi based on surface area alone, with multiple views on the influence of loading conditions and failure modes remaining unresolved.

Contextual Notes

Participants note the need for additional information regarding dimensions, material properties, and the mode of failure to provide a reliable answer.

Tryzxobbnym123
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We performed an experiment on a rectangular box of measured dimensions made from a certain material. We loaded the box with weights until mechanical failure. So, I know the dimensions of the box and the amount of force put on it until it failed. Would I be able to accurately calculate and report the psi of the material we used by simply calculating the surface area of the box and doing the math? Or, is this test inaccurate because the point of mechanical failure might be dependent on the geometry of the rectangular box?
 
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Was this experiment designed to test the strength of the component? Or was it happenstance that you applied too much weight and it failed?
 
Mech_Engineer said:
Was this experiment designed to test the strength of the component? Or was it happenstance that you applied too much weight and it failed?
It was designed to test the strength of the component.
 
Tryzxobbnym123 said:
Would I be able to accurately calculate and report the psi of the material we used by simply calculating the surface area of the box and doing the math?
The answer is almost certainly NOT based on the surface area of the top of the box. The method would depend on how the weight was applied to the box. For example the top of the box might fail due to point loads of the applied weight.

If the box was loaded symmetrically then all the walls would have been under compression. If the walls were then crushed, and so failed without buckling, the “psi” would be the total weight in pounds, divided by the cross sectional area of the walls measured in square inches.

You need to give a lot more information about dimensions, material and mode of failure before a reliable answer can be given.
 
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Are you trying to create a 3-point flexural bending test?

Three_point_flexural_test.jpg
 
Please describe the nature of the failure.
 

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