Can the allowable stress value be rounded up?
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This post was last edited by SDHZZXM on 2017-10-14 at 13:43. When establishing a custom material database, it is necessary to determine the allowable stress for S30408 stainless steel plates at room temperature in the Rp1.0 condition; the yield strength at Rp1.0 is 250 MPa. Using a safety factor of 1.5, the calculated allowable stress is 166.666666 MPa. Is it possible to round this allowable stress to 167 MPa? I think it’s possible. What do you all think?
In my opinion, to ensure safety, the allowable stress value can be rounded down to 166 MPa.
Retain one or two decimal places; do not round up
After checking several values from the allowable stress tables in GB/T150.2, it was found that many of them had been rounded off
After checking several values from the allowable stress tables in GB/T150.2, it was found that many of them had been rounded off
Round down to minimize unnecessary complications
In my opinion, when it comes to engineering design, it is fine to round off the calculation results (keeping at least three significant figures), and this has nothing to do with safety. The detection deviations of the mechanical properties of materials and the dimensional deviations are much larger than the rounding errors in the calculated results. The strength calculation uses allowable stress, rather than the material’s tensile strength directly. When the hydrostatic pressure of the liquid column is less than 5% of the design pressure, it can be ignored. So, what impact will rounding off the calculation results have on device safety? If the standard does not specify it, the designer decides.
In my opinion, when it comes to engineering design, it is fine to round off the calculation results (keeping at least three significant figures), and this has nothing to do with safety. The detection deviations of the mechanical properties of materials and the dimensional deviations are much larger than the rounding errors in the calculated results. The strength calculation uses allowable stress, rather than the material’s tensile strength directly. When the hydrostatic pressure of the liquid column is less than 5% of the design pressure, it can be ignored. So, what impact will rounding off the calculation results have on device safety? If the standard does not specify it, the designer decides.