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Fedél mintafeladat – Femap v11 Tube Cap Finite Elements Analysis

Femap v11 Example

By János DEVECZ

(2017)

1.1 Example – Tube Cap

1.2 Example Overview – Assembled Parts (Cut View)

Cap

Bolt

Washer

Hex Nut

Gasket

Tube-flange

Internal

Pressure

Loads

• bolt pretension and pressure

Constraints

• friction and interference fit

1.3 Tube Cap Overview – Applied Loads & Constraints

p = 10 MPa (3 x)

(internal pressure)

Fe = 20 kN (4 x)

(bolt pretension)

Friction area (4 x)

(fixed in all directions)

Flange (transitional fit)

(constraint only radially)

Equivalent cylinder

(pressure volume)

Loads

• bolt pretension and pressure

Constraints

• friction and interference fit

2.1 Import Geometry

The choice depends on the

Units, set in CAD software!

(Unit in CAD & FEM = mm)

Cap.par

Cap.par

File name: Cap.par

2.2 Views – Geometry (model)

3.1 Geometry Preparation – Define Washer

Washer (circular area around a hole)

• effect surface of bolt pretension

• effect surface of friction

3.2 Geometry Preparation – Define Washer (top)

3.3 Geometry Preparation – Finished Washer (top)

3.4 Geometry Preparation – Define Washer (bottom)

3.5 Geometry Preparation – Finished Washer (bottom)

3.6 Geometry Preparation – Exit Washer Command

4.1 Meshing – TetMesh

4.2 Meshing – Open Material Database

4.3 Meshing – Select Material (X-40 Cast)

4.4 Meshing – Material Confirmation

[MPa]

4.5 Meshing – Set Avgerage Element Size

Avg. element size

No Midside Nodes necessary

[mm]

4.6 Meshing – Finished Mesh

5.1 Loads – Create New Dataset (1)


Loads


1..Loads

5.4 Loads – Applying (On Surface)

5.5 Loads – Select Washer Surfaces (top)

5.6 Loads – Set Force value – Bolt (Z)

Bolt (Z)

[N]

[4 x]

5.7 Loads – Select Dome Surfaces (inner)

5.8 Loads – Set Prerssure value – Pressure (p)

Pressure (p)

[MPa]

6.1 Constraints – Create New Dataset (1)


Constraints


1..Constraints

6.4 Constraints – Applying (On Surface)

6.5 Constraints – Select Washer Surfaces (bottom)

6.6 Constraints – Set Constraint values – Bolt (FIX)

Bolt (FIX)

6.7 Constraints – Select Flange Surfaces (two half)

6.8 Constraints – Set Constraint values – Flange (RAD)

Flange (RAD)

7.1 Define Analysis Type

<optional name>

7.2 Run Analysis

8.1 Results – Select Deformed and Contour Data

8.2 Results – Set Contour Options

8.3 Results – Show Stresses (von Mises)

[MPa]

8.4 Results – Define Cutting Plane (1)

8.5 Results – Define Cutting Plane (2)

8.6 Results – Select Cutting Plane

8.7 Results – Set Contour Options

8.8 Results – Show Stresses (von Mises) (Cut)

[MPa]

9.1 Global Remeshing – Delete Old Mesh (1)

9.2 Global Remeshing – Delete Old Mesh (2)

9.3 Global Remeshing – Define New Mesh – TetMesh

Geometry (model) Show/Hide

9.4 Global Remeshing – New Average Element Size

New Avg. Element Size

10.1 Local Remeshing – Meshing Toolbox

According to Curve(s)

Increase Nodes

Multply by Factor

Number of Elements

Equal Spacing

10.2 Local Remeshing – Using Curves

Select Curve(s) to Remeshing

10.3 Local Remeshing – Remeshed Regions

No. of Nodes, No. of Elements

11.1 ReAnalysed – Show Stresses (Von Mises)

Analyse [MPa]

11.2 Nodal Stress (Von Mises) inquiry (1)

[MPa]

11.3 Nodal Stress (Von Mises) inquiry (2)

Examined

Node

[MPa]

12.1 Convergence Curve – Overview

Steps to Convergence Curve:

1. Designate an examined point (preferably geometric point)

2. Meshing + Analyze Note the number of Elements (E) and

Stress () at the test point (Node)

3. Refine mesh + Analyze (with unchanged boundary conditions)

Note the number of Elements (E) and Stress () at the test point

(Node)

4. Repeat the step 3 as often as necessary

5. Plot the corresponding number of Elements and Stress pairs in

the E- coordinate system

6. Fit the convergence curve to the points

7. The asymptote of the fitted curve will be the accepted Stress

No. of Elements (E)

Von Mises

Stress

[MPa]

Mesh4; E=15312 Mesh5; E=21983 Mesh3; E=11734 Mesh2; E=8664 Mesh1; E=6715

xceba)x(f

a = 77.567249

b = 599.61779

c = 0.00049989295

Convergence-curve

red,1=56.5 MPa

red,2=70.3 MPa

red,5=78.7 MPa

red,3=75.1 MPa

~78 MPa

1

2

3

4

5

1

2

3 4

5

red,4=76.4 MPa

12.2 Convergence Curve – Plot

Examined Node

Accepted range

THE END

Connection rod Buckling Analysis

Femap v11 Example

By János DEVECZ

(2017)

Pcr

The buckling (Experiment) The buckling is an instability, leading to a failure. In practice, buckling is characterized by a sudden failure of a structural member subjected to high compressive stress, where the actual compressive stress at the point of failure is less than the ultimate compressive stresses that the material is capable of withstanding.

Pcr Pcr Pcr

The buckling (Theory)

Pcr Pcr Pcr Pcr Pcr Pcr

Air compressor – Conection rod

Connection rod (3D model)

Connection rod (Material, Load and Constraints)

F = 20000 N

Constraints:

TX, TY, RX, RZ

Required safety factor

against buckling:

Sreq = 6-10

Deformed shape

Undeformed shape

Constraint:

Pinned – No Translation

Material: 70 Ni (with Chromium) Wrought

THE END

Crankshaft Modal Analysis

Femap v11 Example

By János DEVECZ

(2017)

The resonance is a tendency of a system to oscillate with greater amplitude at some frequencies than at others. Frequencies at which the response amplitude is a relative maximum are known as the system's resonant frequencies or resonance frequencies. At these frequencies, even small periodic driving forces can produce large amplitude oscillations, because the system stores vibrational energy.

Resonance (theory)

Crankshaft Torsional Vibration

Torsional vibration is a concern in the crankshafts of internal combustion engines because it could break the crankshaft itself; shear-off the flywheel; or cause driven belts, gears and attached components to fail, especially when the frequency of the vibration matches the torsional resonant frequency of the crankshaft. Causes of the torsional vibration are attributed to several factors.

Air compressor - Crankshaft

Crankshaft (modal analysis)

bearing

bearing

Load: Fy = 20000 N

Constraints:

Radial Growth

Fy (force)

X

Y

Z

Resonance Frequencies [Hz] Critical Rotational Speeds [1/min]

Critical Frequency Range = 10...15 % of Resonance Frequency

Constraints:

Radial Growth

Constraints:

No Rotation

THE END

1

Shaft FEM Analysis (Bending & Torsion)

By János DEVECZ

(2017)

Femap v11 Example

Shaft and pulley arrangement with Loads

Fh

Fk

T

Fh

D

D = 224 mm

Fk

Torque:

Tnom = 160 Nm

Fk

2

Tangential Force:

Fk = 1500 N

Shaft Tension Force:

Fh ≈ 2Fk = 3000 N

Tnom

Fh

Fh = 3000 N

Tnom = 160∙103 Nmm Torsion Torque (moment)

FEM analysis - Shaft Loads

3

Tension force Bending

3D model of Shaft (Solid Edge ST3)

Filename: shaft.par

4

Geometry dimensons:

Surface roughness:

Material (Femap):

d = 25 j6 mm | D = 40 mm | l = 42 mm | L = 62 mm | lret = 32mm

Ra,shaft = 1.6 mm | Ra,shoulder = 3.2 mm

AISI Carbon Steel 1025 Cold Drawn

Technical drawing of Shaft (Solid Edge ST3)

5

Finite Elements Analysis (Femap v11.01)

6

File -> Import ->

Geometry…

{shaft.par}

|OK|

File -> Save

{shaft.modfem}

|OK|

• Import Geometry and Save the FEM model

Geometry -> Curve –From

Surface -> Parametric

Curve…

Select Surface for

Parametric Curve: (Select

the half cylinder (1))

Method^ : On Point

Select Location for

Parametric Curve: (Select

the point (2))

() V-Direction

|OK| |Cancel|

(Repeat for surface (3) and

point (4), and the back half

cylinder)

7

•Preparation of Model surfaces: Surface splitting

8

(The yellow surfaces on the

pictures show the splitted

surfaces)

•Preparation of Model surfaces: Surface splitting – Result

•Meshing the Geometric model

Mesh -> Geometry ->

Solids…

Material: AISI Carbon Steel

1025 Cold Drawn

|OK|

Midside Nodes [<NO>]

|Update Mesh Sizing…|

Element Size: [3]

|OK|

9

•Defining the Loads – Bending

11

Model -> Load -> Set…

ID [1] Title: [loads]

|Done|

Model -> Load -> On

Surface…

Entity Selection: (Select the

yellow surface on the picture)

|OK|

Title: [bending]

Force

Direction:

() Components

FX [3000], FY [0], FZ [0]

(Listen to the sign of Force!)

|OK| |Cancel|

•Defining the Loads – Torsion

12

Model -> Load -> On

Surface…

Entity Selection: (Select the

yellow surface on the picture)

|OK|

Title: [torsion]

Torque

Direction:

() Magnitude only

Magnitude [160000]

(Listen to the sign of Torque!)

|OK|

Base: X [0] Y [0] Z [0]

Tip: X [0] Y [1] Z [0]

|OK|

•Show results – Deformation and Von Mises Stress

14

View -> Select…

Deformed Style:

() Deform

Contour Style:

() Contour

|Def. and Contour Data…|

Output Sets:

[1..NX NASTRAN Case 1]

Output Vectors:

Deform:

[1..Total Translation]

Contour:

[60031..Solid Von Mises

Stress]

|OK| |OK|

15

THE END

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