Hello everyone,
I am performing a dynamic analysis test on SHPB Test Sample. I have attached a sample code for the same:
model new
block tolerance corner-round-length 3.4E-7
block tolerance minimum-edge-length 6.8E-4
block contact tolerance overlap 0.010
block create polygon 0 0 0 0.050 5.016 0.050 5.016 0
block cut crack 2.975 0 2.975 0.050
block cut crack 3.009 0 3.009 0.050
block hide
block seek id-list 1,2
block zone gen quad 0.010
block zone cmodel assign elastic density 8000 bulk 166.7e9 shear 76.92e9 range pos-x 0 2.975
block zone cmodel assign elastic density 8000 bulk 166.7e9 shear 76.92e9 range pos-x 3.009 5.016
block seek
block hide id-list 1,2
block cut crack 2.975 0.008 3.009 0.008
block cut crack 2.975 0.042 3.009 0.042
block delete id-list 3,5
block cut voronoi edge-maximum 0.004 iterations 100 round 1E-4
block zone gen edge 0.004
block hide id-list 1,2
block zone cmodel assign elastic density 1900 bulk 5.397E9 shear 2.636E9 ;Model Material from Journal
block seek
;Contact Properties
block contact cmodel assign residual st-s 2.5e13 st-n 5E13 friction 55 …
cohesion 80E6 tension 350e6 …
friction-residual 55 cohesion-residual 80E6 tension-residual 350e6
fish define wave
if block.mechanical.time.total > 1.0 / freq
wave = 0.0
else
wave = 1math.sin(1.0math.pifreqblock.mechanical.time.total)
endif
end
fish set @freq=5000
@wave
block gridpoint apply bulk 166.7E9 shear 76.92E9 density 8000
block gridpoint apply visc-x range pos-x 5.016 tolerance 0.00001
block gridpoint apply visc-x range pos-x 0 tolerance 0.00001
block gridpoint apply visc-y range pos-x 5.016 tolerance 0.00001
block gridpoint apply visc-y range pos-x 0 tolerance 0.00001
block edge apply stress 382E6 0.0 0.0 history @wave range pos-x -0.001 0.001 pos-y 0.000 0.050
block mechanical history time-total
block mechanical damping 0.0 0.0
block zone history stress-xx 1.4875 0.050
block zone history stress-xx 4.0125 0.050
block cycle time 2E-3
Here the contact microparameter - Contact tensile strength for a value of 350E6 gives desirable result i.e. Incident+Reflected Stress Pulse should be equal to Reflected Pulse
But isn’t this value not realistic?
Top figure is the stress pulse for incident bar
Bottom figure is the stress pulse for transmission bar
Can somebody please convey what is the issue here?
What should be done so that this contact tensile strength value becomes realistic.
General UCS value of sample is 60 MPa and Tensile Strength is 6MPa