masters project fall 2014 dan flavin 29 september 2014 1903 springfield rifle bolt analysis
TRANSCRIPT
MASTERS PROJECTFALL 2014
DAN FLAVIN29 SEPTEMBER 2014
1903 Springfield Rifle Bolt Analysis
Introduction
Firearms consist of a tube, sealed at one endModern firearms require that the seal be
moveable. The mechanical structure used to provide this seal is called the bolt.
In bolt action rifles, this bolt locks into the main structure of the rifle, called the receiver. This is usually done by lugs on the forward end of the bolt.
Goal
Determine stresses within a rifle bolt using FEA. In this case, the 1903 Springfield rifle used by the US military was chosen
Steps: Geometry: develop a 3D model of the bolt,
in least-material conditionMaterials: determine the material
properties of the steel in the bolt Finite Element Analysis (FEA): determine
the loading of the bolt in a worst-case scenario
Geometry
Only the head of the bolt is modeled, in order to save processing time. 1: Cartridge base 2: Bolt head 3: Receiver ring
Materials
Bolt material is WD2340, equivalent to SAE 2340, a now-obsolete steel alloy.
Property Value
Young’s Modulus, elastic (typical
to steels)
29,700 ksi
Young’s Modulus, plastic
(estimated)
300 ksi
Poisson’s Ration (typical to steels) 0.29
Density 0.284 lb/in3
Yield Stress 128 ksi
Terminal Stress 150 ksi
Finite Element Analysis
The model used the static solid mechanic module (more conservative than dynamic)
Plasticity with strain hardening was added to the model.
Bolt thrust of 75ksi (proof load) was used.
Results: Displacement
Results: von Mises Stress
Note than maximum stress values appear to be artifacts of stress concentrations within the software.
Results: Percent Yield
Isosurfaces shown are of von Mises stress divided by yield stress (including the effects of strain hardening)
Conclusion
The bolt, as modeled, will barely withstand the proof load. However, these conditions do not include strength increase due to rate of strain, and take extreme conditions not likely to be found outside of a testing laboratory.
This modeling technique could be extended to the barrel and receiver for greater accuracy
Further accuracy could also be developed by testing of material properties to get more accurate values