Abstract
A technique for the determination of machine compliance from the unloading portion of an instrumented impact test record is evaluated. Unnotched three-point bend specimens of aluminum, titanium, and steel were tested at various loading rates to determine the effects of specimen material properties on machine-compliance estimates. Results substantiate the validity of determining machine compliance from the unloading protion of the curve. The data also indicate that machine compliance determined in this manner is independent of the specimen material properties, and of the deformation occurring during the uploading portion of the curve.
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Abbreviations
- B :
-
specimen thickness
- E :
-
Young's modulus of elasticity
- g :
-
force due to gravitation
- h i :
-
specimen deflection at timei
- h i+1:
-
specimen deflection at timei+1
- m :
-
mass of hammer assembly
- P a :
-
average force on load cell between timei andi+1
- P i :
-
force recorded by instrumented load cell at timei
- S :
-
specimen anvil span
- U em :
-
elastic energy absorbed by the machine
- U es :
-
elastic energy absorbed by the specimen
- U ps :
-
plastic energy absorbed by the specimen
- U s :
-
total energy absorbed by the specimen
- U tot :
-
energy absorbed by the machine/specimen system
- V a :
-
average hammer velocity between timei, andi+1
- V i :
-
velocity of hammer assembly at timei
- V i+1:
-
velocity of hammer assembly at timei+1
- W :
-
specimen width
- δ b :
-
elastic-deflection contribution from bending
- δ sh :
-
elastic-deformation contribution from shear
- δm i :
-
machine deflection at timei
- δm i+1 :
-
machine deflection at timei+1
- δs i :
-
specimen deflection at timei
- δs i+1 :
-
specimen deflection at timei+1
- δ tot :
-
total elastic deflection
- ν:
-
Poisson's ratio
- σ y :
-
dynamic yield stress
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KarisAllen, K.J., Morrison, J. The determination of instrumented impact machine compliance using unloading displacement analysis. Experimental Mechanics 29, 152–156 (1989). https://doi.org/10.1007/BF02321368
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DOI: https://doi.org/10.1007/BF02321368