OnTime- Visualization for Parallel and Serial Simulation in OpenSees

cypriotcamelΠολεοδομικά Έργα

29 Νοε 2013 (πριν από 4 χρόνια και 1 μήνα)

90 εμφανίσεις

We

present

our

current

work

on

extending

VEES

(Visualizer

for

the

Earthquake

Engineering

System)

and

OpenSees

to

handle

visualization

during

and

or

after

a

parallelized

or

serial

simulation

run
.

Our

lightweight

framework

leverages

existing

superclasses

within

OpenSees

while

providing

the

necessities

to

load

state

time

step

by

time

step
.






The

source

code

for

the

simulation

runs

with

a

launch

of

VEES

replacing

analysis

commands,

and

the

user

can

pause

and

examine

constitutive

state

at

each

time

step
.


We

add

two

classes

to

OpenSees,

DomainRecorder

and

File_Channel
.


DomainRecorder

is

a

subclass

of

Recorder
.

Recorders

perform

some

action

on

each

commit

step

in

a

simulation
.

DomainRecorder

records

the

current

state

of

the

entire

simulation

domain

(stress,

strain,

stiffness,

deformation)

by

taking

advantage

of

the

MovableObject

interface’s

sendSelf

and

recvSelf

method
.

Elements,

Materials,

and

the

Domain

itself

are

all

required

to

implement

these

methods
.

The

interface

was

originally

designed

to

assist

with

parallelization

by

serializing

objects

to

send

to

other

compute

nodes
.

We

use

it

instead

to

capture

state

on

each

commit
.



The

state

of

the

entire

simulation

domain

is

saved

to

file

using

the

existing

sendSelf

methods,

with

the

caveat

that

presently

some

Finite

Elements’

sendSelf

methods

capture

only

material

constants,

not

stress,

strain

or

other

kinematic

properties
.


VEES

has

been

extended

to

load

domain

state

in

a

similar

fashion

(using

recvSelf)

and

the

graphical

user

interface

has

likewise

been

extended

to

facilitate

incrementing

and

decrementing

time

steps,

or

run

an

entire

simulation

as

a

movie
.


It

can

handle

changes

in

the

domain

such

as

removing

or

adding

elements

since

the

visualizer

essentially

runs

the

same

experiment

as

the

cluster,

but

without

computati
on
.

New Constitutive Visualizations






















Brick Gauss Points colored by


ii
2


The

latest

capability

is

to

select

a

single

brick

element,

and

then

a

single

gauss

point

within

the

element

to

examine

the

stiffness

tensor
.

We

use

the

idea

of

a

Reynolds

Glyph

which

morphs

a

unit

sphere

using

the

formula

E
ijkl
n
i
n
j
n
k
n
l

where

n

is

a

vector

of

unit

length

from

the

origin

of

the

sphere

to

the

surface
.
[
1
]

E
ijkl

can

also

be

decomposed

into

6

eigentensors

that

show

isotropic

stiffness

and

stiffness

along

shear

planes
.
[
2
]



















The open source code is available
through NEESforge and is free for non
-
commercial and academic use.

[1] Kriz

[2] Helnwein, Taran

OnTime
-

Visualization for Parallel and Serial
Simulation in OpenSees

Investigators:

Alisa Neeman


UC Santa Cruz
(Role: Principal Investigator)

Boris Jeremic


UC Davis

Alex Pang


UC Santa Cruz


Space Costs:


For

a

simulation

of

231

elements,

the

majority

soil

elements

with

material

Template
3
Dep

(kinematic

hardening,

scalar,

vector

or

tensorial

evolution

laws)
.







Future

work

includes

compression

with

zlib

which

can

reduce

storage

costs

one

order

of

magnitude
.

Storage

costs

could

be

further

reduced

be

keeping

a

single

copy

of

static

elastic

material

properties

(rather

than

one

per

gauss

point)
.




Performance
:


4

Frames

per

second

for

231

elements

On

2
.
4

Ghz

Intel

Core

2

Duo

with

Nvidia

GeForce

7900

GS

graphics

card
.























Additional

Interactivity


One

previous

weakness

of

VEES

was

the

inability

to

view

a

scalar

value

such

as

stress

or

deformation

using

a

single

color

scale

across

multiple

time

steps
.

This

feature

has

now

been

added
;

a

user

can

set

the

maximum

value

after

loading

the

final

time

step,

and

view

other

time

steps

using

the

same

scale
.

NEES Facilities Used:

NEESforge








1 timestep

7.5 MB

1000 timesteps

~7.5 GB

40,000 timesteps

~300 GB