The valve had 3 circumferential grooves near the top of the stem to hold the collet and spring
retainer, 0.0015 units diameter in a stem diameter of 0.008 units with a valve head diameter of 0.040 units
and a total length of 0.1 units)
The model assumed a load (of 100 units) in the positive 'Y' direction was applied around the top semi-circular groove in the stem.
The theoretical tensile stress in the stem is: 1.989e6.
The von Mises stress plots below indicate that the maximum stress concentration effects
of these grooves was a maximum of about 2.3.
When the maximum principal stress plot is examined (not shown here) the stress concentration factor of the grooves is 3.
The stress concentration, on a maximum principal stress plot (not shown here) where the stem joins the head, where a 0.0075 unit radius was used, is much lower, about 1.6 times that of the mean stress in the stem. (1.3 on the von Mises plot).
Plot of von Mises stresses in stem by grooves.
Plot of von Mises stresses at radius of stem and head.
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David Grieve 5th February 2003.