How should tensile strength be considered in limit load analysis using finite elements?
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I’ve seen that in the analysis of the ultimate load capacity of structures in some materials documents, an ideal elastoplastic model is used – that is, just by entering the yield strength, the calculation can be done. But how is the tensile strength of the material taken into account? If the yield strength ratio of the material is relatively high, the allowable stress of the material is determined by its tensile strength. Therefore, for a simple structure such as a spherical shell or a cylindrical shell, the wall thickness obtained using formulaic methods should differ from the result obtained through limit load analysis, which seems unreasonable.
My language skills are quite poor; I’m not sure if everyone will be able to understand.
Do you mean the formula method you mentioned refers to the formula in 150? 150 represents elastic failure; I can’t remember the specifics. Different failure modes lead to different outcomes, so there must be something unreasonable about this
In the case of JB4732, comparing the results obtained by using the formulas in the analytical design standards with those from the ultimate load method shows that there is still a significant difference for materials with a high yield strength ratio
Your question isn’t clearly worded. As I understand it, the ultimate load does not allow for the calculation of the required thickness; rather, the thickness is estimated first, and then adjusted through calculations. Finite element analysis will only provide the stress distribution; it is up to you to determine whether it meets the requirements. A positive order of solution when using the formula allows for obtaining the required minimum thickness. Finite element calculation is a reverse process; it determines whether the thickness is acceptable or not based on the results of the calculations.