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ParFUM from an Application Perspective M. Scot Breitenfeld

ParFUM from an Application Perspective

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ParFUM from an Application Perspective. M. Scot Breitenfeld. Motivation. Finite element code 3-D Cohesive/volumetric finite element (CVFE) scheme for spontaneous dynamic fracture Uses cohesive element for fracture events. Pure tensile (mode I) - D t = 0 . Normal Traction Law. - PowerPoint PPT Presentation

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Page 1: ParFUM from an Application Perspective

ParFUM from an Application Perspective

M. Scot Breitenfeld

Page 2: ParFUM from an Application Perspective

Motivation

• Finite element code – 3-D Cohesive/volumetric finite element (CVFE)

scheme for spontaneous dynamic fracture• Uses cohesive element for fracture events

Page 3: ParFUM from an Application Perspective

Normal Traction Law Shear Traction Law

Tn

n

max

GIc

nc

Pure tensile (mode I) - t = 0

Page 4: ParFUM from an Application Perspective

Motivation– Explicit dynamic (central difference time stepping

scheme)• No large system of equations to solve

– Nonlinear kinematics (large strains, large rotations) – Nonlinear constitutive models

• Hyperelastic – Neo-Hookean (compressible, incompressible)– Mooney-Rivlin– Arruda-Boyce

• Nonlinear constitutive laws– Viscoplastic

– Original implementation used MPI

Page 5: ParFUM from an Application Perspective

Motivation• MPI based code limitations

– No adaptive load balancing• Non-trivial using MPI• Load balancing for adaptive mesh changes

– insertion/activation of cohesive elementsDeflection of a crack by a material interface

Weak interfaceStrong interface

(Experimental results by Xu, Huang and Rosakis, 2001)

Page 6: ParFUM from an Application Perspective

Motivation

– Load imbalance due to material models

• 3D Plastic Fracture• A single edge notched

specimen pulled at both ends with a ramping magnitude of 1 m/s over .01 seconds

•  Isosurface is the extent of the plastic zone  

Page 7: ParFUM from an Application Perspective

Motivation• A 1x1x10 bar loaded with a ramped velocity of magnitude 0. to 40. over a

time period of (0.1*length of bar)/(fastest wave speed) and held constant afterward

Page 8: ParFUM from an Application Perspective

Application

• MPI

• Reads in mesh– created with a meshing tool

• Partitions the mesh• Create communication lists for

the processors• Transfer boundary conditions to

the partitioned mesh

• ParFUM

• No pre-processor needed

• Automatically– Partitions– Creates the

communication list– Handles the

boundary conditions

Typical Procedure for a Parallel FEM Code

PRE-PROCESSOR

Page 9: ParFUM from an Application Perspective

Application

• MPI

• Insert MPI calls to handle communications: Send, Recieves waits, etc….

• ParFUM

• Solution Code

• Communication calls are simplified..

Typical Procedure for a Parallel FEM Code

Solution Code

Page 10: ParFUM from an Application Perspective

Application

• ParFUM

Typical Procedure for a Parallel FEM Code DO j1 = 1, NumNeighProcs k = IdNeighProc(j1) CALL MPI_IRECV(frmproc(k)%rcvbuf(1),COMMON(j1)*3,& MPI_DOUBLE_PRECISION,k,10,MPI_COMM_WORLD,& req_rcv(j1),ierr) ENDDO

k2 = 1 DO j1 = 1, NumNeighProcs k = IdNeighProc(j1) k3 = COMMON(j1)*3 CALL MPI_ISEND(buf(k2),k3,MPI_DOUBLE_PRECISION,& k,10,MPI_COMM_WORLD,req_snd(j1),ierr) k2 = k2 + k3 ENDDO

CALL MPI_WAITALL(NumNeighProcs,req_rcv,stat_rcv,ierr) CALL MPI_WAITALL(NumNeighProcs,req_snd,stat_snd,ierr) DO j1 = 1, NumNeighProcs k = IdNeighProc(j1) k1 = 1 DO j = 1, COMMON(j1) k2 = XCom(j1)%node_list(j)*3 Rnet(k2-2)= Rnet(k2-2) + frmproc(k)%rcvbuf(k1) Rnet(k2-1)= Rnet(k2-1) + frmproc(k)%rcvbuf(k1+1) Rnet(k2) = Rnet(k2) + frmproc(k)%rcvbuf(k1+2) k1 = k1 + 3 ENDDO ENDDO

CALL FEM_Update_Field(fid_R_net,R_net)

Page 11: ParFUM from an Application Perspective

Application

• MPI

• Typically needed to put the mesh back together for visualization

• ParFUM

• Typically Not Needed– ParFUM will output

the “serial” mesh

Typical Procedure for a Parallel FEM Code

Post-Processor

Page 12: ParFUM from an Application Perspective

Conclusion• ParFUM is considerably easier then creating an

MPI version• MPI is not practical (in terms of development

time) for applications needing adaptive load balancing

• ParFUM is continually adding new features of interest to the FE community:– Parallel Adaptive Mesh Refinement (including

activation of cohesive elements)– Parallel contact detection and enforcement