Spall Fracture of Multi-Material Plates Under Explosive Loading
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Transcript of Spall Fracture of Multi-Material Plates Under Explosive Loading
Spall Fracture of Multi-Material Plates Under Explosive LoadingEngineering Project Second Progress Report PresentationBy James Danyluk
Spall Fracture in Solids Shock waves traveling through a solid material is
reflected at changes in material or free surfaces. These reflected shock waves are known as rarefaction
waves or relief waves. When a free surface and rarefaction wave interact, a
tensile stress can be generated in the solid material.◦ This can also happen with two rarefaction waves
interact. If this tensile stress exceeds the dynamic tensile
strength, or spall strength, the material can fracture.
Hydrocode Model ANSYS AUTODYN, an explicit dynamics code, was
used to model the system. The Euler Multi-material solver was used. The model was setup with an Explosive, Solid Material
and Air layers. The analysis modeled different materials and material
combinations◦ The tensile wave generated in the solid material(s) was
examined in each model. The analysis was separated into four sets of iterations
◦ 1D Elastic only material models◦ 1D Elastic/Plastic material models◦ 1D Elastic/Plastic/Failure material models◦ 2D Elastic/Plastic/Failure material models
Hydrocode ModelSingle Plate Model
Two Plate Model
Three Plate Model
Trial Layer 1 Layer 2 Layer 31 6061-T6 - -2 Steel v250 - -3 304L - -4 Tung - -5 6061-T6 Tung -6 Tung 6061-T6 -7 304L Tung -8 Tung 304L -9 Polyethylene Tung -
10 Tung Polyethylene -11 Steel v250 Tung -12 Tung Steel v250 -13 Tung 304L Tung14 Tung 6061-T6 Tung15 Tung Polyethylene Tung16 304L Tung 304L17 Steel v250 Tung Steel v25018 6061 Tung 606119 Polyethylene 304L Tung20 Tung 304L Polyethylene
Single Plate Hydrocode ResultsAl6061-T6 Plate
Single Plate Hydrocode ResultsShock wave in explosive Shock wave in plate
Rarefaction wave generated
Two Plate ResultsTungsten/Polyethylene Combination Tungsten/304L Steel Combination
Three Plate ResultsTungsten/Polyethylene/Tungsten 304L/Tungsten/304L
Spall Failure Model ResultsTungsten/Aluminum
Aluminum/Tungsten
Current Conclusions Stacking materials can dictate how spall failures occur For most cases, the outer solid layer developed spall
planes, while the inner layer remained intact.◦ This method can be used to develop “spall plates”, plates that are
intentionally designed to spall off, leaving the desired material (inner layer) intact.
When a highly dense material (tungsten) is mated next to a very low density material (aluminum, polyethylene), a rarefaction wave can be generated by the material interface that will cause the tungsten plate to spall.◦ Other material combinations did produce rarefaction waves, but
they were not large enough to overcome the explosive loading and produce a tensile stress in the plate.
◦ In these cases, the spall can happen in both the inner and outer layers, but the amount of spall is highly reduced in the outer layer.
Schedule/Milestones 9/21/10: Submit Proposal 9/28/10: Complete Hand Calculations/Finish Research 10/5/10: Complete 1-D Elastic Hydrocode Model
Results 10/12/10: Complete 1-D Elastic/Plastic Hydrocode
Model Results 10/19/10: Submit First Progress Report 10/26/10: Complete 1-D Elastic/Plastic/Failure
Hydrocode Model Results 11/9/10: Submit Second Progress Report 11/18/10: Complete 2-D Elastic/Plastic/Failure
Hydrocode Model Results 11/30/10: Submit Final Draft 12/14/10: Submit Final Report