Container Impact in Water Using LS-DYNAMatt Wesleymwesley@hawaii.eduUniversity of Hawaii at Manoa7/6/12

Outline

• Beginning stages

• Model setups

• Results so far

• Future work

Beginning Steps

• Learning to use LS-DYNA

• Running SMP or MPP• shared memory parallel or massive parallel processing

Model Setup

• Need an accurate model to test in air and in water

• 1:5 scale of a 20ft shipping container

• Made from acrylic

 

 

 48 in

Side view

48.5 in

20.4 in

Solid or Shell Elements• Shell elements yield even at low velocities

• Solid elements hold up much better

Acrylic Box Model• Material: PLASTIC_KINEMATIC• E=3.2 GPa• ρ=1200 kg/m3

• ν=0.37

• Dimensions:• Base: modeled as solid elements, thickness of 0.024 m• Base also has a lip, this is where the contact will be made

• Top: modeled as shell elements, thickness of 0.012 m

Contact • First, created a wall with the same width as the

box• Used rigid material • Set it to be stationary

• Next, created a ‘load cell’• Used the same rigid material and made it stationary

• Varied the speed at which the box impacted

Model verification• *A*v

• When contact area is the whole base:• Fact = 39800N • Fest = 39504N

• This is using an adjusted density of 3560 kg/m3

Impact forces on a 0.1016m diameter cylinder

Estimation uses adjusted density of 5893 kg/m3

0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.50

20000400006000080000

100000120000140000160000180000200000 Force vs Velocity

SimulationEstimation

Velocity (m/s)

Forc

e (N

)

OSU test setup

• Viscous flow with an initial velocity

• BIG!!!

• Need to add a column with a ‘load cell’ and the acrylic box model

• Just using basic properties for now until the model works

Problems• Need to void the interior of the box• *INITIAL_VOLUME_FRACTION_GEOMETRY

• What is the best ratio of ALE nodes per Lagrangian node

• Long run times!!!

Timeframes

9 10 11 12 13 16 17 18 19 20 23 24 25 26 27 30 31 1 2

OSU test setup

empty inside of box

correct constraints on column and box

compare forces for in air and in water

final report

Conclusion• Starting out with LS-DYNA

• Results so far

• Future work and problems

Sources• Paczkowski, K. Riggs, H.R. Naito, C.J. Lehmann, A. A one-

dimensional model for impact forces resulting from high mass, low velocity debris. Structural Engineering and Mechanics. Vol. 42. No. 6. 2012. Pages 831-847.

• http://www.encyclopedia2.thefreedictionary.com/MPP

• LS-DYNA Theory Manual