Effect of Polyurea on Dynamic Response of Steel Plates Experimental Investigation Introduction The...
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Effect of Polyurea on Dynamic Response of Steel Plates Experimental Investigation Introduction The dynamic behavior of circular plates, with deflections in the range where both bending moments and membrane forces are important, is investigated experimentally and numerically. This type of loading is typical in high strain-rate events such as impact- and blast- loading leading to catastrophic results. Therefore there is ongoing need to improve the energy absorbing characteristics of steel plates. One of the most convenient ways of enhancing the energy absorption of the steel plates and improving the resistance to fracture in dynamic events is to use polyurea. Therefore, the effect of polyurea on the fracture mode and energy absorption characteristics of steel plates is studied, focusing on the effect of the relative location of steel and polyurea layers with respect to the loading Nature of the Problem The polyurea can have a significant impact on the mechanical response of the steel plate under dynamic impulsive loading both in terms of failure resistance and energy absorbing capacity, if used appropriately as backing of the plate. This experimental observation has been also proved computationally using detailed finite element models employing very accurate constitutive models for DH-36 steel and Conclusions and Results In this work we addressed the effect of the polyurea on the dynamic behavior of steel plates. The failure process of the steel plates can be captured with the new experimental setup leading to a better insight into the failure mechanisms of the steel plates. Summary & Future Directions Student : Mahmoud Reza Amini Advisor : Prof. Sia Nemat- Nasser http://ceam.ucsd.edu Dynamic Impulsive Loading of Steel Plate Enhance the Energy Absorbing Characteristics Effect of Polyurea on Steel Plate Dynamic Response Polyurea-Steel Layers Design Configuration Polyurea in Front Polyurea in Back No Polyurea = steel plate = polyurea = impact side s u b j e c t P r o b l e m Experiment al Investigat ion Computatio nal Evaluation Effect of Polyurea on Steel Plate Fracture 3-inch Hopkinson Bar Ultra high speed camera, Imacon 200 LS-DYNA (FEM) User-Defined Materials Constitutive Models Fracture Mode and Severity, Shear Band and Necking T o p i c s o f I n v e s t i g a t i o n s 3-inch Steel Bar Al 7075 Cylinde r Steel Confinement Polyureth ane DH-36 Steel Plate 17-4 pH Steel Ring V 0 Project ile Gas Gun Barrel Gas Gun Barrel Project ile Polyuretha ne Confinemen t Steel Bar V 0 Severe Failure Slight Failure No Failure Top View Side View Experiments Without Ring, Cylinder #1 Test# ImpactVelocity (m /s) Input Energy (J) Energy per Thickness (J/cm ) Fracture Type 8 68.90 1726.64 16579.95 No 9 73.20 1929.28 19180.76 Slight 10 71.83 1840.78 18823.84 Severe 11 70.06 1733.22 18422.39 Slight 12 72.30 1830.33 17925.43 No 13 72.40 1816.63 17970.03 Slight Test# ImpactVelocity (m /s) Input Energy (J) Energy per Thickness (J/cm ) Fracture Type 14 71.92 1933.89 19373.35 Severe 15 71.80 1929.33 19327.72 No 16 71.58 1912.43 19109.76 No 17 71.95 1934.48 19833.53 Slight 18 71.69 1921.88 19204.20 No 19 71.92 1935.17 19435.64 No 20 73.48 2017.46 20902.03 Severe 21 73.55 2022.46 20681.71 Severe Energy per Thickness > 17950 (J/cm) Fractu re Energy per Thickness > 19500 (J/cm) Fractu re Experiments With Ring, Cylinder #1 Test# ImpactVelocity (m /s) Input Energy (J) Energy per Thickness (J/cm ) Fracture Type D escription 26 72.09 1942.66 19259.13 No Flat 27 72.50 1961.84 19855.44 Severe Flat 28 70.45 1848.66 19551.92 Severe Dish 29 76.36 2108.21 21499.05 Slight Flat 31 72.25 1951.45 19568.01 Severe Dish 32 71.71 2084.90 21013.13 Severe Flat 36 64.91 1597.68 16128.43 Severe D ish+PU /fronted 41 72.41 1985.00 20867.69 No Flat+PU /backed 42 72.23 1990.09 18693.69 No Flat+PU /backed 44 76.65 2231.35 21022.63 No Flat+PU /backed 45 76.35 2185.37 20436.65 Severe Flat 46 67.03 1686.82 16128.73 Severe Dish 48 67.69 1718.82 16700.9 Severe Dish 51 67.34 1703.45 15994.02 Severe Dish Experiments Without Ring, Cylinder #2 Without Polyurea Backing With Polyurea Backing Impact Velocity = 76.65 m/s Input Energy = 2231.35 J Thickness = 0.1061 cm Energy/Thickness = 21016.4 J/cm Impact Velocity = 74.75 m/s Input Energy = 2084.90 J Thickness = 0.0992 cm Energy/Thickness = 21012.9 J/cm No Failure Severe Failure Without Polyurea Fronting With Polyurea Fronting Impact Velocity = 64.90 m/s Input Energy = 1597.68 J Thickness = 0.0991 cm Energy/Thickness = 16128.4 J/cm Impact Velocity = 67.34 m/s Input Energy = 1703.40 J Thickness = 0.1040 cm Energy/Thickness = 16378.8 J/cm Severe Failure Severe Failure Experimental Setup Flat Dish + PU/Fronted Flat + PU/Backed Cylinde r Cylinde r Plate Cylinde r Plate Plate Polyure a Polyure a Polyuretha ne Polyuretha ne Polyuretha ne Dish Cylinde r Plate Polyuretha ne Four different configurations of steel plate and polyurea layers Experimental Results At large deformations (deflection/thickness > 10) the membrane effect is predominant. Thus the behavior of the steel plate is proportional to the inverse of the thickness DH-36 Steel Plate 3” outer diameter M = 90~95 g t = 0.038”~0.041” The most important experimental quantities include: Imparted energy (mass of projectile, ring and plate and projectile velocity) Steel plate thickness Polyurea location if used Plates behave as simply-supported Failure can be qualitatively categorized as shown: Necking and shearbanding are typical mechan-isms of failure of the steel plates under ultra-high velocity dynamic stretching conditions The experimental setup (ring and cylinder design) was changed slightly to obtain more systematic and reliable results; comparison is made among the various results As presented in Table 3, plates impacted at Energy per Thickness greater than 19,500 (J/cm) with Polyurea backing did not fracture, but the Polyurea-fronted plates fractured at Energy per Thickness value of 16,100 (J/cm) (<<19500 J/cm) 1. Polyurea backing can mitigate failure 2. Polyurea fronting may promote failure Ongoing Research New Experimental Setup Table 1. Bare steel impacting on flat side, first Al- cylinder deign without ring Table 2. Bare steel impacting on flat side, first Al- cylinder design with ring Table 3. Impact condition, second Al-cylinder design (attached ring) UC San Diego Mechanical and Aerospace Engineering Center of Excellence for Advanced Materials UC San Diego Mechanical and Aerospace Engineering Center of Excellence for Advanced Materials UC San Diego Mechanical and Aerospace Engineering Center of Excellence for Advanced Materials UC San Diego Mechanical and Aerospace Engineering Center of Excellence for Advanced Materials UC San Diego Mechanical and Aerospace Engineering Center of Excellence for Advanced Materials UC San Diego Mechanical and Aerospace Engineering Center of Excellence for Advanced Materials UC San Diego Mechanical and Aerospace Engineering Center of Excellence for Advanced Materials UC San Diego Mechanical and Aerospace Engineering Center of Excellence for Advanced Materials Using water to apply shock pressure on the steel plate instead of polyurethane Deformation process, crack propagation and failure modes are being captured with the new setup Steel Plate Impacted on the Flat Side (with and without polyurea) Steel Plate Impacted on the Dish Side (with and without polyurea)
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Transcript of Effect of Polyurea on Dynamic Response of Steel Plates Experimental Investigation Introduction The...
Effect of Polyurea on Dynamic Response of Steel PlatesExperimental Investigation
IntroductionThe dynamic behavior of circular plates, with deflections in the range where both bending moments and membrane forces are important, is investigated experimentally and numerically. This type of loading is typical in high strain-rate events such as impact- and blast-loading leading to catastrophic results. Therefore there is ongoing need to improve the energy absorbing characteristics of steel plates.
One of the most convenient ways of enhancing the energy absorption of the steel plates and improving the resistance to fracture in dynamic events is to use polyurea. Therefore, the effect of polyurea on the fracture mode and energy absorption characteristics of steel plates is studied, focusing on the effect of the relative location of steel and polyurea layers with respect to the loading direction.
Nature of the ProblemThe polyurea can have a significant impact on the mechanical response of the steel plate under dynamic impulsive loading both in terms of failure resistance and energy absorbing capacity, if used appropriately as backing of the plate. This experimental observation has been also proved computationally using detailed finite element models employing very accurate constitutive models for DH-36 steel and polyurea.
Conclusions and ResultsIn this work we addressed the effect of the polyurea on the dynamic behavior of steel plates. The failure process of the steel plates can be captured with the new experimental setup leading to a better insight into the failure mechanisms of the steel plates.
Summary & Future Directions
Student: Mahmoud Reza Amini
Advisor: Prof. Sia Nemat-Nasser
http://ceam.ucsd.edu
Dynamic Impulsive Loading of Steel Plate
Enhance the Energy Absorbing Characteristics
Effect of Polyurea on Steel Plate Dynamic Response
Polyurea-Steel Layers Design Configuration
Polyurea in Front
Polyurea in Back
No Polyurea
= steel plate = polyurea = impact side
subjectP
roblem
Experimental Investigation
Computational Evaluation
Effect of Polyurea on Steel Plate Fracture
3-inch Hopkinson Bar
Ultra high speed camera, Imacon 200
LS-DYNA (FEM)
User-Defined Materials Constitutive Models
Fracture Mode and Severity, Shear Band and Necking
Topics of Investigations
3-inch Steel Bar
Al 7075 Cylinder
Steel Confinement
PolyurethaneDH-36 Steel Plate
17-4 pH Steel Ring
V0
Projectile
Gas Gun Barrel
Gas Gun BarrelProjectile
Polyurethane
ConfinementSteel Bar
V0
Severe Failure
Slight Failure
No Failure
Top View Side View
Experiments Without Ring, Cylinder #1
Test #Impact Velocity
(m/s)Input
Energy (J)Energy per
Thickness (J/cm)Fracture
Type8 68.90 1726.64 16579.95 No 9 73.20 1929.28 19180.76 Slight10 71.83 1840.78 18823.84 Severe11 70.06 1733.22 18422.39 Slight12 72.30 1830.33 17925.43 No 13 72.40 1816.63 17970.03 Slight
Test #Impact Velocity
(m/s)Input
Energy (J)Energy per
Thickness (J/cm)Fracture
Type
14 71.92 1933.89 19373.35 Severe15 71.80 1929.33 19327.72 No 16 71.58 1912.43 19109.76 No 17 71.95 1934.48 19833.53 Slight18 71.69 1921.88 19204.20 No 19 71.92 1935.17 19435.64 No 20 73.48 2017.46 20902.03 Severe21 73.55 2022.46 20681.71 Severe
Energy per Thickness > 17950 (J/cm) Fracture
Energy per Thickness > 19500 (J/cm) Fracture
Experiments With Ring, Cylinder #1
Test #Impact Velocity
(m/s)Input
Energy (J)Energy per
Thickness (J/cm)Fracture
TypeDescription
26 72.09 1942.66 19259.13 No Flat27 72.50 1961.84 19855.44 Severe Flat28 70.45 1848.66 19551.92 Severe Dish29 76.36 2108.21 21499.05 Slight Flat31 72.25 1951.45 19568.01 Severe Dish32 71.71 2084.90 21013.13 Severe Flat36 64.91 1597.68 16128.43 Severe Dish+PU/fronted41 72.41 1985.00 20867.69 No Flat+PU/backed42 72.23 1990.09 18693.69 No Flat+PU/backed44 76.65 2231.35 21022.63 No Flat+PU/backed45 76.35 2185.37 20436.65 Severe Flat46 67.03 1686.82 16128.73 Severe Dish48 67.69 1718.82 16700.9 Severe Dish51 67.34 1703.45 15994.02 Severe Dish
Experiments Without Ring, Cylinder #2
Without Polyurea BackingWith Polyurea Backing
Impact Velocity = 76.65 m/s
Input Energy = 2231.35 J
Thickness = 0.1061 cm
Energy/Thickness = 21016.4 J/cm
Impact Velocity = 74.75 m/s
Input Energy = 2084.90 J
Thickness = 0.0992 cm
Energy/Thickness = 21012.9 J/cm
No Failure Severe Failure
Without Polyurea FrontingWith Polyurea Fronting
Impact Velocity = 64.90 m/s
Input Energy = 1597.68 J
Thickness = 0.0991 cm
Energy/Thickness = 16128.4 J/cm
Impact Velocity = 67.34 m/s
Input Energy = 1703.40 J
Thickness = 0.1040 cm
Energy/Thickness = 16378.8 J/cm
Severe FailureSevere Failure
Experimental Setup
Flat Dish + PU/FrontedFlat + PU/Backed
Cylinder Cylinder
Plate
Cylinder
Plate
PlatePolyurea
Polyurea
Polyurethane PolyurethanePolyurethane
Dish
Cylinder
Plate
Polyurethane
Four different configurations of steel plate and polyurea layers
Experimental Results
At large deformations (deflection/thickness > 10) the membrane effect is predominant. Thus the behavior of the steel plate is proportional to the inverse of the thickness
DH-36 Steel Plate
3” outer diameter
M = 90~95 g t = 0.038”~0.041”
The most important experimental quantities include:
Imparted energy (mass of projectile, ring and plate and projectile velocity)
Steel plate thickness
Polyurea location if used
Plates behave as simply-supported
Failure can be qualitatively categorized as shown:
Necking and shearbanding are typical mechan-isms of failure of the steel plates under ultra-high velocity dynamic stretching conditions
The experimental setup (ring and cylinder design) was changed slightly to obtain more systematic and reliable results; comparison is made among the various results
As presented in Table 3, plates impacted at Energy per Thickness greater than 19,500 (J/cm) with Polyurea backing did not fracture, but the Polyurea-fronted plates fractured at Energy per Thickness value of 16,100 (J/cm) (<<19500 J/cm)
1. Polyurea backing can mitigate failure
2. Polyurea fronting may promote failure
Ongoing Research
New Experimental Setup
Table 1. Bare steel impacting on flat side, first Al-cylinder deign without ring
Table 2. Bare steel impacting on flat side, first Al-cylinder design with ring
Table 3. Impact condition, second Al-cylinder design (attached ring)
UC San Diego Mechanical and Aerospace Engineering Center of Excellence for Advanced Materials UC San Diego Mechanical and Aerospace Engineering Center of Excellence for Advanced Materials UC San Diego Mechanical and Aerospace Engineering Center of Excellence for Advanced Materials UC San Diego Mechanical and Aerospace Engineering Center of Excellence for Advanced Materials
UC San Diego Mechanical and Aerospace Engineering Center of Excellence for Advanced Materials UC San Diego Mechanical and Aerospace Engineering Center of Excellence for Advanced Materials UC San Diego Mechanical and Aerospace Engineering Center of Excellence for Advanced Materials UC San Diego Mechanical and Aerospace Engineering Center of Excellence for Advanced Materials
Using water to apply shock pressure on the steel plate instead of polyurethane
Deformation process, crack propagation and failure modes are being captured with the new setup
Steel Plate Impacted on the Flat Side (with and without polyurea)
Steel Plate Impacted on the Dish Side (with and without polyurea)
