Simulation of Waterjet Erosion

Simulation of WaterjetSimulation of WaterjetErosionErosion

Using ANSYS/LS-DYNAUsing ANSYS/LS-DYNAAnd Smoothed Particle Hydrodynamics (SPH)And Smoothed Particle Hydrodynamics (SPH)

Mike ValantMike Valant

ME 8364ME 8364Steve GroothuisSteve Groothuis

Smoothed Particle HydrodynamicsSmoothed Particle Hydrodynamics

Matter is represented by particles of fixed Matter is represented by particles of fixed massmass Conservation equations are expressed as Conservation equations are expressed as inter-particle forcesinter-particle forces Mechanical equations are expressed as the Mechanical equations are expressed as the summation of interpolants (interpolation summation of interpolants (interpolation equations), using a kernel function W with a equations), using a kernel function W with a smoothing function h. smoothing function h.

Smoothed Particle HydrodynamicsSmoothed Particle HydrodynamicsIntegration CycleIntegration Cycle

Bucket Sort

Abrasive Waterjet Erosion ProcessAbrasive Waterjet Erosion Process

Erosion Testing MachineErosion Testing Machine


Monolithic Erosion Test SamplesMonolithic Erosion Test Samples

4545° from normal° from normal 00° from normal° from normal


Multilayered Erosion Test SamplesMultilayered Erosion Test Samples


Erosion is a micro-scale process which Erosion is a micro-scale process which occurs over long periods of timeoccurs over long periods of time The cumulative effect of erosion is the sum The cumulative effect of erosion is the sum of millions of high-speed microscopic impactsof millions of high-speed microscopic impacts A true model of abrasive waterjet erosion A true model of abrasive waterjet erosion would include millions of micro-scale events would include millions of micro-scale events integrated over a time scale many orders of integrated over a time scale many orders of magnitude larger than that of each individual magnitude larger than that of each individual event.event. Therefore, for this model, several Therefore, for this model, several approximations and adjustments are madeapproximations and adjustments are made

Abrasive Waterjet Erosion ModelAbrasive Waterjet Erosion Model

Abrasive Waterjet – SPH ParticlesAbrasive Waterjet – SPH Particles

1.25mm diameter Quartz Sand1.25mm diameter Quartz Sand

Density – 2.65 g/ccDensity – 2.65 g/cc

Elastic Modulus – 70 GPaElastic Modulus – 70 GPa

Compressive Yield Strength – 1100MPaCompressive Yield Strength – 1100MPa

Poisson’s Ratio – 0.17Poisson’s Ratio – 0.17

Shear Modulus – 31 GPaShear Modulus – 31 GPa

Material model - *MAT_ELASTIC_PLASTIC_HYDROMaterial model - *MAT_ELASTIC_PLASTIC_HYDRO

Equation of State - GruneisenEquation of State - Gruneisen


Workpiece – Lagrangian ElementsWorkpiece – Lagrangian Elements

6061 T6511 Aluminum6061 T6511 Aluminum

Density – 2.785 g/ccDensity – 2.785 g/cc

Elastic Modulus – 68.9 GPaElastic Modulus – 68.9 GPa

Yield Strength – 276MPaYield Strength – 276MPa

Ultimate Tensile Strength – 310 MPaUltimate Tensile Strength – 310 MPa

Poisson’s Ratio – 0.33Poisson’s Ratio – 0.33

Shear Modulus – 27 GPaShear Modulus – 27 GPa

Material Model - *MAT_PLASTIC_KINEMATICMaterial Model - *MAT_PLASTIC_KINEMATIC


Model DimensionsModel Dimensions

Jet Diameter – 4cmJet Diameter – 4cmJet Length – 15cmJet Length – 15cmJet Speed – 3000 km/s (1% of speed of light!)Jet Speed – 3000 km/s (1% of speed of light!)Jet angles from normal - 1Jet angles from normal - 1°, °, 22.522.5°, °, 4545°, °, 67.567.5° ° Workpiece length and width – 12cmWorkpiece length and width – 12cmWorkpiece layer thickness – 3mmWorkpiece layer thickness – 3mmNumber of layers - 5Number of layers - 5


Sample code - ANSYSSample code - ANSYS

/PREP7 /PREP7 !---------------------------------------------------!---------------------------------------------------! ELEMENT DEFINITION! ELEMENT DEFINITION!---------------------------------------------------!---------------------------------------------------ET,1,SOLID164ET,1,SOLID164KEYOPT,1,1,1KEYOPT,1,1,1 ! = 0,1 (Constant stress solid element)! = 0,1 (Constant stress solid element)

! = 2 (Fully integrated selectively-reduced solid)! = 2 (Fully integrated selectively-reduced solid)KEYOPT,1,5,0KEYOPT,1,5,0 ! = 0 (LAGRANGIAN), =1 (1PT ALE)! = 0 (LAGRANGIAN), =1 (1PT ALE)

! = 1 ALE (Arbitrary Lagrangian-Eulerian)! = 1 ALE (Arbitrary Lagrangian-Eulerian)ET,2,MESH200ET,2,MESH200 ! Not solved element! Not solved elementKEYOPT,2,1,6KEYOPT,2,1,6 ! 4-node meshing element! 4-node meshing element!---------------------------------------------------!---------------------------------------------------! GEOMETRIC PARAMETERS! GEOMETRIC PARAMETERS!---------------------------------------------------!---------------------------------------------------PI PI = acos(-1)= acos(-1) ! definition of pi! definition of piRCYLRCYL = 2= 2 ! jet radius [cm] --- changed from 2! jet radius [cm] --- changed from 2HCYLHCYL = 15 = 15 ! jet column height [cm]! jet column height [cm]XBLOCKXBLOCK = 12 = 12 ! workpiece width [cm]! workpiece width [cm]YBLOCKYBLOCK = 12= 12 ! workpiece length [cm]! workpiece length [cm]NUMLAYER = 5NUMLAYER = 5 ! number of workpiece layers! number of workpiece layersAVGBLOCK=(XBLOCK+YBLOCK)/2AVGBLOCK=(XBLOCK+YBLOCK)/2 ! AVERAGE NUMBER FOR MESHING! AVERAGE NUMBER FOR MESHINGZBLOCKZBLOCK = 0.3= 0.3 ! workpiece LAYER height [cm]! workpiece LAYER height [cm]ZTOTAL = ZBLOCK*NUMLAYER ! total height of workpieceZTOTAL = ZBLOCK*NUMLAYER ! total height of workpieceRCYL2RCYL2 = 2*RCYL= 2*RCYL ! jet radius on workpiece [cm] --- changed from 2*rcyl! jet radius on workpiece [cm] --- changed from 2*rcylIANGIANG = 67.5= 67.5 ! jet angle from normal [deg]! jet angle from normal [deg]!!

Abrasive Waterjet Erosion ModelAbrasive Waterjet Erosion ModelSample code - ANSYSSample code - ANSYS

! BASE BLOCK! BASE BLOCK!!RECT,0,XBLOCK,0,YBLOCKRECT,0,XBLOCK,0,YBLOCK ! MAKE RECTANGLE ! MAKE RECTANGLE!!MSHKEY,1 ! NOT free meshingMSHKEY,1 ! NOT free meshingTYPE,2TYPE,2MAT,WPIECE2MAT,WPIECE2ESIZE,AVGBLOCK/WPIECEMESHESIZE,AVGBLOCK/WPIECEMESHAMESH,ALLAMESH,ALL!!! BUILD LAYER 1! BUILD LAYER 1!!ALLSELALLSELTYPE,1TYPE,1 ! SELECT 3D ELEMENT TYPE! SELECT 3D ELEMENT TYPEMAT,WPIECE1MAT,WPIECE1EXTOPT,ESIZE,1,0, ! Val1 (1) sets the number of element EXTOPT,ESIZE,1,0, ! Val1 (1) sets the number of element divisions in the direction of volume generation or volume divisions in the direction of volume generation or volume sweep.sweep.! Val2 sets the spacing ratio (bias) in ! Val2 sets the spacing ratio (bias) in the direction of volume generation (zero calls default, the direction of volume generation (zero calls default, uniform spacing=1) uniform spacing=1) VEXT,ALL, , ,0,0,ZBLOCK,,,,VEXT,ALL, , ,0,0,ZBLOCK,,,,!!


!---------------------------------------------------!---------------------------------------------------! SOLID MESHING FOR WATERJET! SOLID MESHING FOR WATERJET!---------------------------------------------------!---------------------------------------------------!!MSHAPE,0,3D MSHAPE,0,3D SMRT,MCYL ! Overall element size level for meshing. The level value SMRT,MCYL ! Overall element size level for meshing. The level value controls the fineness of the mesh.controls the fineness of the mesh.!! 1 is finest mesh, 10 is coarsest 1 is finest mesh, 10 is coarsest!!! SPH CYLINDER! SPH CYLINDERMAT,WJETMAT,WJETVSWEEP,NUMLAYER+1VSWEEP,NUMLAYER+1!!ALLSEL $ CMSE,ALLALLSEL $ CMSE,ALL!!MODMSH,DETACHMODMSH,DETACH!---------------------------------------------------!---------------------------------------------------! COMPONENT DEFINITION FOR WATERJET PLUS DELETE WATERJET ELEMENTS! COMPONENT DEFINITION FOR WATERJET PLUS DELETE WATERJET ELEMENTS!---------------------------------------------------!---------------------------------------------------ESEL,S,MAT,,WJETESEL,S,MAT,,WJETNSLE,S,1NSLE,S,1CM,SPHNODES,NODECM,SPHNODES,NODEEDEL,ALLEDEL,ALL!!ALLSEL $ CMSE,ALLALLSEL $ CMSE,ALL!!


!---------------------------------------------------!---------------------------------------------------! GATHER CONSTRAINED NODE DATA! GATHER CONSTRAINED NODE DATA!---------------------------------------------------!---------------------------------------------------nsel,s,loc,z,0nsel,s,loc,z,0 ! select all nodes on z0 plane! select all nodes on z0 planen1=0n1=0 ! set n1 to 0! set n1 to 0cn=ndinqr(0,13)cn=ndinqr(0,13) ! return number of selected entities! return number of selected entities*dim,cnodes,,cn,1*dim,cnodes,,cn,1 ! define a FORTRAN-like array with cn rows, one column, and one ! define a FORTRAN-like array with cn rows, one column, and one plane (default one plane)plane (default one plane)*do,indx,1,cn*do,indx,1,cn ! do loop, counter indx, start from 1 and go to cn! do loop, counter indx, start from 1 and go to cnn1=ndnext(n1)n1=ndnext(n1) ! n1 now equals next selected node having a node number greater ! n1 now equals next selected node having a node number greater than n1, where n1 started at 0than n1, where n1 started at 0cnodes(indx,1)=n1cnodes(indx,1)=n1 ! value of cnodes at row (indx) equals n1! value of cnodes at row (indx) equals n1*enddo*enddo ! end of do loop! end of do loopcmin=cnodes(1,1)cmin=cnodes(1,1) ! cmin equals the first node in cnodes! cmin equals the first node in cnodescmax=cnodes(cn,1)cmax=cnodes(cn,1) ! cmax equals the last node in cnodes! cmax equals the last node in cnodesallsel $ cmse,allallsel $ cmse,all ! reselect all! reselect all!---------------------------------------------------!---------------------------------------------------! GATHER SPH NODE DATA! GATHER SPH NODE DATA!---------------------------------------------------!---------------------------------------------------CMSE,S,SPHNODESCMSE,S,SPHNODESN1=0N1=0SPHN=NDINQR(0,13)SPHN=NDINQR(0,13)*DIM,SNODES,,SPHN,4*DIM,SNODES,,SPHN,4 ! define a FORTRAN-like array with SPHN rows, four columns, and ! define a FORTRAN-like array with SPHN rows, four columns, and one plane (default one plane)one plane (default one plane)*DO,INDX,1,SPHN*DO,INDX,1,SPHN ! do loop, counter indx, start from 1 and go to ! do loop, counter indx, start from 1 and go to SPHNSPHNN1=NDNEXT(N1)N1=NDNEXT(N1)SNODES(INDX,1)=N1SNODES(INDX,1)=N1 ! NODE NUMBER! NODE NUMBERSNODES(INDX,2)=NX(N1)SNODES(INDX,2)=NX(N1) ! X-CCORDINATE! X-CCORDINATESNODES(INDX,3)=NY(N1)SNODES(INDX,3)=NY(N1) ! Y-COORDINATE! Y-COORDINATESNODES(INDX,4)=NZ(N1)SNODES(INDX,4)=NZ(N1) ! Z-COORDINATE! Z-COORDINATE*ENDDO*ENDDOSMIN=SNODES(1,1)SMIN=SNODES(1,1)SMAX=SNODES(SPHN,1)SMAX=SNODES(SPHN,1)


!---------------------------------------------------!---------------------------------------------------! EXPORT DATA TO WJBORE.K! EXPORT DATA TO WJBORE.K!---------------------------------------------------!---------------------------------------------------*VWRITE*VWRITE('*KEYWORD')('*KEYWORD')*VWRITE*VWRITE('$ cm micros GPa')('$ cm micros GPa')*VWRITE*VWRITE('*TITLE')('*TITLE')*VWRITE,TVELO,IANG*VWRITE,TVELO,IANG('Waterjet Boring: Particle Speed :',G8.2,'km/s at',G8.2,'deg')('Waterjet Boring: Particle Speed :',G8.2,'km/s at',G8.2,'deg')*VWRITE*VWRITE('*CONTROL_TERMINATION')('*CONTROL_TERMINATION')*VWRITE,ENDTIM*VWRITE,ENDTIM%10.6f%10.6f*VWRITE*VWRITE('*CONTROL_TIMESTEP') ! timestep scale factor TSSFAC is usually from .67 to .9, ('*CONTROL_TIMESTEP') ! timestep scale factor TSSFAC is usually from .67 to .9, not .2not .2*VWRITE*VWRITE(' 0.0000000 0.200000 0 0.0000000 0.0000000 0 0 (' 0.0000000 0.200000 0 0.0000000 0.0000000 0 0 0')0')*VWRITE*VWRITE('*CONTROL_SHELL')('*CONTROL_SHELL')*VWRITE*VWRITE(' 0.0000000 0 0 0 9 0 0')(' 0.0000000 0 0 0 9 0 0')*VWRITE*VWRITE('*CONTROL_DAMPING')('*CONTROL_DAMPING')*VWRITE*VWRITE(' 0 0.0000000 0.0000000 0.0000000 0.0000000 0 0.0000000 (' 0 0.0000000 0.0000000 0.0000000 0.0000000 0 0.0000000 0')0')

Abrasive Waterjet Erosion ModelAbrasive Waterjet Erosion ModelSample code – LS-DYNASample code – LS-DYNA

*MAT_PLASTIC_KINEMATIC*MAT_PLASTIC_KINEMATIC 1 7.8500000 0.7000000 0.2900000 290.000-5 0.0700000 1.0000000 0.00000001 7.8500000 0.7000000 0.2900000 290.000-5 0.0700000 1.0000000 0.0000000 0.0000000 0.0000000 0 00.0000000 0.0000000 0 0*MAT_PLASTIC_KINEMATIC*MAT_PLASTIC_KINEMATIC 2 7.8500000 0.7000000 0.2900000 290.000-5 0.0700000 1.0000000 0.00000002 7.8500000 0.7000000 0.2900000 290.000-5 0.0700000 1.0000000 0.0000000 0.0000000 0.0000000 0 00.0000000 0.0000000 0 0*MAT_PLASTIC_KINEMATIC*MAT_PLASTIC_KINEMATIC 3 7.8500000 0.7000000 0.2900000 290.000-5 0.0700000 1.0000000 0.00000003 7.8500000 0.7000000 0.2900000 290.000-5 0.0700000 1.0000000 0.0000000 0.0000000 0.0000000 0 00.0000000 0.0000000 0 0*MAT_PLASTIC_KINEMATIC*MAT_PLASTIC_KINEMATIC 4 7.8500000 0.7000000 0.2900000 290.000-5 0.0700000 1.0000000 0.00000004 7.8500000 0.7000000 0.2900000 290.000-5 0.0700000 1.0000000 0.0000000 0.0000000 0.0000000 0 00.0000000 0.0000000 0 0*MAT_PLASTIC_KINEMATIC*MAT_PLASTIC_KINEMATIC 5 7.8500000 0.7000000 0.2900000 290.000-5 0.0700000 1.0000000 0.00000005 7.8500000 0.7000000 0.2900000 290.000-5 0.0700000 1.0000000 0.0000000 0.0000000 0.0000000 0 00.0000000 0.0000000 0 0*MAT_ELASTIC_PLASTIC_HYDRO*MAT_ELASTIC_PLASTIC_HYDRO 10 2.6450000 31.0000-2 110.000-4 0.0000000 -2.000-02 0.000000010 2.6450000 31.0000-2 110.000-4 0.0000000 -2.000-02 0.0000000 0.0000000 0.0000000 0.0000000 0.0000000 0.0000000 0.0000000 0.0000000 0.00000000.0000000 0.0000000 0.0000000 0.0000000 0.0000000 0.0000000 0.0000000 0.0000000 0.0000000 0.0000000 0.0000000 0.0000000 0.0000000 0.0000000 0.0000000 0.00000000.0000000 0.0000000 0.0000000 0.0000000 0.0000000 0.0000000 0.0000000 0.0000000 0.0000000 0.0000000 0.0000000 0.0000000 0.0000000 0.0000000 0.0000000 0.00000000.0000000 0.0000000 0.0000000 0.0000000 0.0000000 0.0000000 0.0000000 0.0000000 0.0000000 0.0000000 0.0000000 0.0000000 0.0000000 0.0000000 0.0000000 0.00000000.0000000 0.0000000 0.0000000 0.0000000 0.0000000 0.0000000 0.0000000 0.0000000*EOS_GRUNEISEN*EOS_GRUNEISEN 3 0.5328000 1.3390000 0.0000000 0.0000000 2.0000000 0.4800000 0.00000003 0.5328000 1.3390000 0.0000000 0.0000000 2.0000000 0.4800000 0.0000000 0.00000000.0000000*MAT_ADD_EROSION*MAT_ADD_EROSION 1 8881 888 888 888 888 .25 888 888 888888 888 888 .25 888 888 888


Early solution with plastic deformation but no erosion modelEarly solution with plastic deformation but no erosion model

Material and jet are plotted as a cross-sectionMaterial and jet are plotted as a cross-section

Maximum plastic strain is over 100%Maximum plastic strain is over 100%


Impact angle 67.5Impact angle 67.5° from Normal° from NormalModel GeometryModel Geometry


Impact angle 67.5Impact angle 67.5° from Normal° from NormalReverse Elevated View – Von Mises StressReverse Elevated View – Von Mises Stress


Impact angle 67.5Impact angle 67.5° from Normal° from NormalSide View – Von Mises StressSide View – Von Mises Stress


Impact angle 67.5Impact angle 67.5° from Normal° from NormalBottom View – Plastic StrainBottom View – Plastic Strain


Impact angle 67.5Impact angle 67.5° from Normal° from NormalTop View, Jet Not Shown – Plastic StrainTop View, Jet Not Shown – Plastic Strain


Impact angle 45Impact angle 45° from Normal° from NormalModel GeometryModel Geometry


Impact angle 45Impact angle 45° from Normal° from NormalElevated View – No Fringe LevelsElevated View – No Fringe Levels


Impact angle 45Impact angle 45° from Normal° from NormalSide View – No Fringe LevelsSide View – No Fringe Levels


Impact angle 45Impact angle 45° from Normal° from NormalTop View – Plastic StrainTop View – Plastic Strain


Impact angle 22.5Impact angle 22.5° from Normal° from NormalModel GeometryModel Geometry


Impact angle 22.5Impact angle 22.5° from Normal° from NormalElevated View – No Fringe LevelsElevated View – No Fringe Levels


Impact angle 22.5Impact angle 22.5° from Normal° from NormalElevated View – Von Mises StressElevated View – Von Mises Stress


Impact angle 22.5Impact angle 22.5° from Normal° from NormalElevated Side View, Cross-Section – Plastic StrainElevated Side View, Cross-Section – Plastic Strain


Impact angle 1Impact angle 1° from Normal° from NormalModel GeometryModel Geometry


Impact angle 1Impact angle 1° from Normal° from NormalElevated View – No Fringe LevelsElevated View – No Fringe Levels


Impact angle 1Impact angle 1° from Normal° from NormalElevated View – Von Mises StressElevated View – Von Mises Stress


Impact angle 1Impact angle 1° from Normal° from NormalElevated View, Cross-Section – Plastic StrainElevated View, Cross-Section – Plastic Strain


Impact angle 1Impact angle 1° from Normal° from NormalSide View, Cross Section – Plastic StrainSide View, Cross Section – Plastic Strain


Impact angle 1Impact angle 1° from Normal° from Normal

Side View, Cross Section – Plastic StrainSide View, Cross Section – Plastic Strain

Note Shape of DeformationNote Shape of Deformation

Model Correlation, AKA “Goodness”Model Correlation, AKA “Goodness”

Some of the major overall effects of abrasive waterjet Some of the major overall effects of abrasive waterjet erosion are present in this model:erosion are present in this model:

1.1. The impact and erosion patterns on the The impact and erosion patterns on the workpiece surface are similar in shape to the workpiece surface are similar in shape to the erosion patterns seen in experiments.erosion patterns seen in experiments.

2.2. A decrease in impact angle (relative to normal) A decrease in impact angle (relative to normal) results in an increase in the erosion rate. This is results in an increase in the erosion rate. This is true for very high-speed abrasive waterjets.true for very high-speed abrasive waterjets.

3.3. The erosion shape in cross-section is similar to The erosion shape in cross-section is similar to the shape seen in experiments. the shape seen in experiments.

Future WorkFuture Work

There are many parts of the model which can be improved or There are many parts of the model which can be improved or augmented:augmented:

1.1. Model geometry should equal experimental geometry.Model geometry should equal experimental geometry.

2.2. Abrasive waterjet speed should be closer to the experimental Abrasive waterjet speed should be closer to the experimental speed.speed.

3.3. If possible, a finer mesh for the workpiece and for the waterjet If possible, a finer mesh for the workpiece and for the waterjet should be employed. Also a much longer waterjet is desirable.should be employed. Also a much longer waterjet is desirable.

4.4. The waterjet mesh should be more uniform to enhance SPH The waterjet mesh should be more uniform to enhance SPH solution stability.solution stability.

5.5. Artificial particle penetration and contact instability issues Artificial particle penetration and contact instability issues should be addressed.should be addressed.

6.6. The waterjet particle distribution can be improved by using a The waterjet particle distribution can be improved by using a Gaussian-distributed mesh to more accurately represent the Gaussian-distributed mesh to more accurately represent the true particle distribution in a typical waterjet. true particle distribution in a typical waterjet.

7.7. Materials of different properties can be used for different Materials of different properties can be used for different workpiece layers to simulate laser-deposited hard coatings.workpiece layers to simulate laser-deposited hard coatings.

THANK YOUTHANK YOU

Many thanks go to Steve Groothuis, without whom this project would Many thanks go to Steve Groothuis, without whom this project would not have been possible. not have been possible.

Thanks must also go to Dr. Kovacevic for encouraging me to enroll in Thanks must also go to Dr. Kovacevic for encouraging me to enroll in this class. this class.

Finally, thank you for being a good audience!Finally, thank you for being a good audience!

Date post:	08-Jan-2016
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Simulation of Waterjet Erosion

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