Crush Pipe Problem

Estimated Time for Completion: ~35minExperience Level: Lower

MSC.Patran 2005 r2MSC.Marc 2005 r2

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Topics Covered

• Topics covered in Modeling• Creating Shell elements by extruding Beam elements

• This is the easiest way to make a 3-D shell structure that has uniform cross section.

• Creating Elastic-perfectly plastic material• The material non-linearity is approximated by a constant

• Applying Equivalence to the redundant nodes.• Equivalence eliminates any duplicated nodes and cracks created by the

mesher. • Topics covered in Analysis

• Applying Deformable and rigid bodies contact• Applying Large Displacement/Large Strains Analysis• Applying Modified Riks/Ramm method

• One of the Increment types which can solve problems with complicate nonlinearity or post-buckling.

• Modifying Contact Table• The contact condition for each contact pair can be modified.

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• A contact between a rigid body and a deformable body is often used in many applications. In this example, A hollow pipe is crushed by moving three rigid cylinders. The rigid cylinders push the pipe surface to a total stroke of 2 inches. Both ends of the pipe are fixed. The material is elastic-perfectly plastic.

Problem Description

Pipe D=8

R=3

R=5

1020

Move 2in in the -Y

Move 2in in the +Y

Rigid – deformable, surface-to-surface contacts

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Problem Description• In this example problem, we apply Symmetric boundary conditions at

the center of the pipe to reduce the number of elements and the analysis time. The following condition is applied at the boundary.• ux=θy= θz=0 on the symmetric boundary

• We will model Elastic-perfectly plastic material properties to simplify the plasticity of the material.

Pipe D=8

R=3

R=5

10

20

Move 2in in the -Y

Move 2in in the +Y

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Summary of Model

• Rigid bodies• Diameters:

• Upper=5 in, Lower=3 in• Motion:

• 2in toward the center of the pipe

• Steel pipe• Dimensions:

• Diameter=8 in,• Length=40 in,• Thickness=0.5 in

• Material properties: • Young’s Modulus =30.0x106 psi,• Poisson’s ratio=0.3,• Yield strength=36000 psi

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Goal

• We will determine the maximum von Mises stress and find the location in the pipe.

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Expected Results

• von Mises Stress

• Displacement, Translation(Magnitude)

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Create Database

a. Click File menu / Select Newb. In File Name enter crushed_pipe.dbc. Click OKd. Select Analysis Code to be MSC. Marce. Click OKf. Click Group menu / Select Createg. In New Group Name enter rigidh. Check Make Currenti. Click Apply

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Create Rigid Bodies

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a. Click Geometry iconb. Select Action to be Createc. Select Object to be Pointd. Select Method to be XYZe. Uncheck Auto Executef. In Point Coordinates List, enter [10,-7.1,4.5]g. Click Applyh. In Point Coordinates List, enter [13,-7.1,4.5]i. Click Applyj. Select Object to be Curvek. Select Method to be Revolvel. In Axis, enter {Point 1[X1 Y1 5.0]}m. In Total Angle, enter 180n. Uncheck Auto Executeo. In Point List, enter Point 2 (or select Point 2)p. Click Apply

Create a curve for the rigid body below the pipe

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Create Rigid Bodies

a. Select Object to be Pointb. Select Method to be XYZc. In Point Coordinates List, enter [0,9.1,4.5]d. Click Applye. In Point Coordinates List, enter [5,9.1,4.5]f. Click Applyg. Select Object to be Curveh. Select Method to be Revolvei. In Axis, enter {Point 4[X4 Y4 5.0]}j. In Total Angle, enter -90k. In Point List, enter Point 5 (or select Point 5)l. Click Apply

Create a curve for the rigid body below the pipeab

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Create Deformable Body

Create a curve for the deformable body

a. Click Group menu / Select Createb. In New Group Name enter pipec. Check Make Currentd. Select Group Contents to be Add Entity Selectione. Click Applyf. Click Cancelg. Select Action to be Createh. Select Object to be Pointi. Select Method to be XYZj. In Points Coordinates List, enter [0,0,0]k. Click Applyl. In Points Coordinates List, enter [0,4,0]m. Click Applyn. Select Object to be Curveo. Select Method to be Revolvep. In Axis, enter {Point 7[1 Y7 Z7]}q. In Total Angle, enter 360r. In Point List, enter Point 8 (or select Point 8)s. Click Apply

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Create Deformable BodyCreate Mesh seed and Mesh on the deformable body

h. Click Group menu / Select Createi. In New Group Name enter fem_pipej. Click Applyk. Click Cancell. Select Action to be Createm. Select Object to be Meshn. Select Type to be Curveo. Select Topology to be Bar2p. In Curve List, enter Curve 3q. Click Apply

a. Click Element iconb. Select Action to be Createc. Select Object to be Mesh Seedd. Select Type to be Uniforme. In Number, enter 20f. In Curve List, enter Curve 3g. Click Apply

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Create Deformable BodyCreate surface elements of the deformable body by extruding the bar elements

a. Select Action to be Sweepb. Select Object to be Elementc. Select Method to be Extruded. In Direction Vector, enter

<20,0,0>e. Check Delete Original Elementsf. In Base Entity List, enter Elm

1:20g. Or select the elements in the

current viewport using the mouse left button

h. Click Apply

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Tip: Select the elements after clicking the icons and

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Create Rigid BodiesCreate surface elements of the rigid bodies by extruding the bar elements

a. Click Group menu / Select Postb. In Select Groups to Post, select

rigidc. Click Applyd. Click Cancele. Select Action to be Createf. Select Object to be Meshg. Select Type to be Curveh. In Curve List, enter Curve 2i. Click Applyj. In Curve List, enter Curve 1k. Click Applyl. Select Action to be Sweepm. Select Object to be Elementn. Select Method to be Extrudeo. Click Mesh Controlp. In Number, enter 1q. Click OKr. In Direction Vector, enter <0,0,-10>s. Check Delete Original Elements

t. In Base Entity List, enter Elm 401:402Or select all element using the left button of the mouse

u. Click Apply

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Applying Equivalence

This will eliminate any extra overlapping nodes created by the mesher. See below for the comparison.

a. Select Action to be Equivalenceb. Select Object to be Allc. Select Method to be Tolerance Cubed. Click Apply

w/o Equivalence with Equivalence

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Verifying the element Normalsa. Select Action to be Verifyb. Select Object to be Elementc. Select Test to be Normalsd. Select Display Control to be Draw Normal Vectore. Click Apply

Wrongdirections

Correctdirections

f. Select Action to be Modifyg. Select Object to be Elementh. Select Method to be Reversei. In the Element List, enter the list of elements with

the wrong directions. Or select them using the mouse left button

j. Click Apply

The Element Normals should point towards the pipe (SEE below). if not,

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Create a group for All FEM

a. Click Group menu / Select Createb. Select Action to be Createc. Select Method to be Select Entityd. In New Group Name, enter fem_alle. Check Make Currentf. Select Group Contents to be Add All FEMg. Click Applyh. Click Cancel

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Create the Material Properties for the pipe

a. Click Materials iconb. Select Action to be Createc. Select Object to be Isotropicd. Select Method to be Manual

Inpute. In Material Name, enter steelf. Click Input Propertiesg. Select Constitutive Model to be

Elastich. In Elastic Modulus, enter 30e6i. In Possion Ratio, enter 0.3j. Click OKk. Click Applyl. Click Input Properties againm. Select Constitutive Model to be

Plasticn. Select Type to be Perfectly

Plastico. In Yield Stress, enter 36000p. Click OKq. Click Apply

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Create the Element Properties for the pipe

a. Click Group menu / Select Postb. In Select Groups to Post, select

fem_pipec. Click Applyd. Click Cancele. Click Properties iconf. Select Action to be Createg. Select Object to be 2Dh. Select Type to be Thick Shelli. In Property Set Name, enter pipej. Select Options to be

Homogeneous andStandard Formulation

k. Click Input Propertiesl. Click Mat Prop Name iconm. Select steeln. In [Thickness], enter 0.5o. Click OKp. In Application Region, enter Elm

1:400 or select elements on the pipe using the mouse left button

q. Click Addr. Click Apply

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Create Boundary Conditions

a. Click Loads/BCs iconb. Select Action to be Createc. Select Object to be Displacementd. Select Type to be Nodale. In New Set Name, enter fixed_dispf. Click Input Datag. In Translations, enter <0,0,0>h. In Rotations, enter <0,0,0>i. Click OKj. Click Select Application Regionk. Select Geometry Filter to be FEMl. In Select Nodes, enter Node

421:440 or select the nodes on the fixed boundary using the mouse left button

m. Click Addn. Click OKo. Click Apply

Create the Fixed Boundary Conditionsa

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Create Boundary Conditions

a. Select Action to be Createb. Select Object to be Displacementc. Select Type to be Nodald. In New Set Name, enter sym_dispe. Click Input Dataf. In Translations, enter <0, , >g. In Rotations, enter < ,0,0>h. Click OKi. Click Select Application Regionj. Select Geometry Filter to be FEMk. In Select Nodes, enter Node 1:20 or

select the nodes on the symmetric boundary using the mouse left button

l. Click Addm. Click OKn. Click Apply

Create the Symmetric Boundary Conditions

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Create Boundary Conditions

a. Click Group menu / Select Postb. In the list, select fem-allc. Click Applyd. Click Cancele. Select Action to be Createf. Select Object to be Contactg. Select Type to be Element Uniformh. Select Option to be Deformable

Bodyi. In New Set Name, enter

contact_midj. Select Target Element Type to be

2Dk. Click Select Application Regionl. Select Geometry Filter to be FEMm. In Select 2D Element, enter Elm

1:400 or select the elements on the pipe using the mouse left button

n. Click Addo. Click OKp. Click Apply

Create the Contact Condition for the deformable body.

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Create Boundary Conditions

a. Select Action to be Createb. Select Object to be Contactc. Select Type to be Element Uniformd. Select Option to be Rigid Bodye. In New Set Name, enter contact_topf. Select Target Element Type to be 2Dg. Click Input Datah. Select Motion Control to be Positioni. In Displacement (vector), enter <0,-2,0>j. Click OKk. Click Select Application Regionl. Select Geometry Filter to be FEMm. In Select 2D Element, enter Elm 401:410 or

select the elements on the upper rigid body using the mouse left button

n. Click Addo. Click OKp. Click Applyq. In New Set Name, enter contact_bottomr. Click Input Datas. In Displacement (vector), enter <0,2,0>t. Click OKu. Click Select Application Regionv. In Select 2D Element, enter Elm 411:420 or

select the elements on the lower rigid body using the mouse left button

Create the Contact Condition for the Rigid Bodies.

w. Click Addx. Click OKy. Click Apply

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Create Boundary Conditions

a. Select Action to be Modifyb. Select Object to be Contactc. Select Type to be Element Uniformd. Select Option to be Rigid Bodye. In Select Set to Modify, select contact_topf. Click Modify Datag. Check Flip Contact Sideh. Click OKi. Click Applyj. In Select Set to Modify, select

contact_bottomk. Click Modify Datal. Check Flip Contact Sidem. Click OKn. Click Apply

Correct the Contact Normal for both rigid bodies. The Contact Normals should be shown as belowab

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Run Analysis

a. Click Analysis iconb. Select Action to be Analyzec. Select Object to be Entire Modeld. Select Method to be Full Rune. In Job Name, enter crushed_pipef. Click Load Step Creationg. In Load Step Name, enter

Pipe_crushh. Select Solution Type to be Statici. Click Solution Parametersj. Select Linearity to be NonLineark. Select Nonlinear Geometry

Effects to be Large Displacement/Large Strains

l. Click Load Increment Parmas

Run Analysis using Nonlinear Analysis Optionsa

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Run Analysisa. Select Increment Type to be

Adaptive Arc Lengthb. Select Arclength Method to be

Modified Riks/Rammc. In Max # of Increments,

enter 100d. Click OKe. Click Iteration Parametersf. In Max # of Iterations per

Increment, enter 75g. Click OKh. Click Contact Tablei. Click Glue Allj. Click OKk. Click OKl. Click Applym. Click Cancel

Run Analysis using Nonlinear Analysis Options

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Run Analysis and Read Results

a. Select Load Step Selectionb. In Existing Load Steps, select

Pipe_crushc. In Selecte Load Step, click

Default Static Step to deselect it.d. Click OKe. Click Apply

Run Analysis using Nonlinear Analysis Options

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Read Results File

f. Select Action to be Read Resultsg. Select Object to be Result Entitiesh. Select Method to be Attachi. Click Select Results Filej. Select crushed_pipe.t16k. Click OKl. Click Apply

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Reviewing the Results

a. Click Results iconb. Select Action to be Createc. Select Object to be Quick Plotd. In Select Result Cases, select the

last results (with Time=1.0)e. In Select Fringe Result, select

Displacement, Translationf. In Select Deformation Result,

select Displacement, Translationg. Click Apply

Check the viewport to see the result plot

h. In Select Fringe Result, select Stress, Global System

i. Select Quantity to be von Misesj. In Select Deformation Result,

select Displacement, Translationk. Click Apply

Check the viewport to see the result plot

Review the Displacement Resultsa

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Results

• von Mises Stress• The location of the

maximum stress in the structure.

• Displacement, Translation(Magnitude)

σmax=4.69x104 psi

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Animation

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Further Analysis (Optional)

• Problem modification• Will removing the fixed boundaries change the location of the

maximum stress? (This is the Pipe-bending problem)

• Modeling• Instead revolving a point, what other methods you can use to

draw circles? What is the advantage of revolving a point?

• Solution options• Do the different values for Max # of Increments and Max # of

Iterations per Increment make different results?• Try with other solution methods (increment types). Can you find

any difference?