SSCon
Mechanical
- Feb 16, 2020
- 79
I've been going through some problems in PTB-5-2013, which is the example problem manual for BPVC VIII-3.
The collapse load in the FEM gives the same maximum allowable working pressure as formula KD221:2 in VIII-3 (to within 1%).
For the local failure example in section 4.4 I'm not getting close results. PTB-5 has given parameters for calculating the strain limit, these are based on the properties of SA-723 (The ratio of yield to ultimate and the reduction in area of 45%). When I use these parameters to get the local strain limit and plot the plastic strain divided by it I get a maximum utilisation of 0.04651. This is a lot less than the 0.299423 shown in figure 12 of PTB-5.
My explanation is that the plot in figure 12 is actually based on the there being no elongation/ reduction in area specified when determining the local strain limit. If I do a plot on this basis I get a maximum utilisation of 0.32652, which is still out by 9% but a lot closer.
Has anyone else come to a similar conclusion when doing this problem?
The collapse load in the FEM gives the same maximum allowable working pressure as formula KD221:2 in VIII-3 (to within 1%).
For the local failure example in section 4.4 I'm not getting close results. PTB-5 has given parameters for calculating the strain limit, these are based on the properties of SA-723 (The ratio of yield to ultimate and the reduction in area of 45%). When I use these parameters to get the local strain limit and plot the plastic strain divided by it I get a maximum utilisation of 0.04651. This is a lot less than the 0.299423 shown in figure 12 of PTB-5.
My explanation is that the plot in figure 12 is actually based on the there being no elongation/ reduction in area specified when determining the local strain limit. If I do a plot on this basis I get a maximum utilisation of 0.32652, which is still out by 9% but a lot closer.
Has anyone else come to a similar conclusion when doing this problem?