Wrap up of the thermal and thermo mechanical simulation on the IBL stave

Simone CoelliMauro Monti

INFN Milano

ATLAS PIXEL

Inserted B-Layer Eng. Meeting

3 February 2009

EDMS PAGES WITH REPORT ON THE FEM SIMULATIONS

ATL-IP-EA-0002 In Work

“Thermo mechanical simulation of the homogeneous stave”

1-REPORT ON THE NEW STAVE THERMO-MECHANICAL FEM SIMULATIONS FOR ATLAS PIXEL DETECTOR B-LAYER REPLACEMENT

2-FINITE ELEMENT METHOD VALIDATION REPORT FOR THERMO-STRUCTURAL SIMULATIONS ON THE NEW STAVE COOLING PIPES

Will be soon upgraded with new updated summary report documents on the FEM simulations

Inserted B-Layer Eng. Meeting 3 February 2009 2

SUMMARY:

Inserted B-Layer Eng. Meeting 3 February 2009 3

The purpose of this document is to summarize the results of FEM simulations carried out till now on the new B-Layer Stave concept for the Atlas Pixel Detector.

Simulation Finite Element Analysis software used is ANSYS code (11.0).

Cross-check calculation have been made using the Classical Laminate Theory (CLT).

The software ESAComp has been used for a cross-check of some laminate thermal expansion coefficient (CTE).

The following subjects have been studied:

- VALIDATION OF THE METHOD: comparison of ANSYS and CLT results for easy to handle problems

- THERMAL STEADY-STATE: temperature field on the new stave with pipe cooling and power on (max heat flux from modules 7200 W/m2)

- STATIC STRUCTURAL MECHANICS: stress and deformation in the composite pipe caused by the internal pressure (design pressure 150 bar) and composites CTE calculation (using a ΔT).

- THERMO-MECHANICAL SIMULATION: full length stave (800 mm) stress and deformation induced by the thermal field, cooling down the stave to -40°C from the ambient temperature 20°C, considering both the alternatives with power on modules or not.

VALIDATION OF THE METHOD

Inserted B-Layer Eng. Meeting 3 February 2009 4

Comparison of ANSYS and CLT results for easy to handle problems These mechanical simulations were performed with standard load conditions provided by the science of construction and the FEM results were compared with the theoretical calculated values, in order to validate the FE models and the boundary conditions applied.

The FE models used have the same characteristics (type of elements, element dimensions, number of elements, etc.) of the components in the Stave FE model

We carried out some mechanical simulations on a pipe under different loading conditions.

The pipe materials in the simulations are aluminium (isotropic) and composite carbon fiber/epoxy laminate with two different lay-up.

VALIDATION OF THE METHOD

Inserted B-Layer Eng. Meeting 3 February 2009 5

Single ply monoaxial stress simulation, changing fibers orientation .

Inserted B-Layer Eng. Meeting 3 February 2009 6

Single ply biaxial stress simulation, changing fibers orientation .

Inserted B-Layer Eng. Meeting 3 February 2009 7

Single ply biaxial stress simulation like in a cylindrical pressure vessel (Mariotte theory) changing fibers orientation .

Inserted B-Layer Eng. Meeting 3 February 2009 8

Single ply shear stress simulation, changing fibers orientation.

Inserted B-Layer Eng. Meeting 3 February 2009 9

Single ply biaxial stress plus shear stress simulation, changing fibers orientation.

Inserted B-Layer Eng. Meeting 3 February 2009 10

Single ply thermal strain due to uniform heating simulation, changing fibers orientation.

Inserted B-Layer Eng. Meeting 3 February 2009 11

Single ply thermal strain due to uniform heating simulation and mechanical stress,

changing fibers orientation.

Inserted B-Layer Eng. Meeting 3 February 2009 12

LAMINATE monoaxial stress simulation, changing lay-up.

Inserted B-Layer Eng. Meeting 3 February 2009 13

LAMINATE biaxial stress simulation, changing lay-up.

Inserted B-Layer Eng. Meeting 3 February 2009 14

LAMINATE ply biaxial stress simulation like in a cylindrical pressure vessel (Mariotte theory) , changing lay-up.

Inserted B-Layer Eng. Meeting 3 February 2009 15

CARBON FIBER COMPOSITE PIPE

biaxial stress simulation as a cylindrical pressure vessel, axial symmetric shell element

changing lay-up, OD, thickness.

Inserted B-Layer Eng. Meeting 3 February 2009 16

CARBON FIBER COMPOSITE PIPE biaxial stress simulation as a cylindrical pressure vessel,

Looking at the strain and stress of the laminate global and in the single plies.

Inserted B-Layer Eng. Meeting 3 February 2009 17

CARBON FIBER COMPOSITE OR METALLIC PIPE

MECHANICAL SIMULATIONS FOR VALIDATION

PIPE FE MODEL The main characteristics of the pipe FE model are the following:•OUTSIDE DIAMETER D = 3.0 mm•INNER DIAMETER d = 2.4 mm•WALL THICKNESS t = 0.30 mm•LENGTH l = 100 mm•AVERAGE RADIUS Rm = 1.35 mm

•FE MODEL ELEMENTS SOLID186 STRUCTURAL for aluminium pipeSOLID186 LAYERED for composite pipe

•NUMBER OF ELEMENTS 3200 (n.32 in the cross section x n.100 along longitudinal axis)•ELEMENT DIMENSIONS 0.3 x 0.3 x 1 (length) mm

•COMPOSITE LAMINATE – LAY UP ± 54.7 Carbon Fiber : T-300 (HR)Matrix: EpoxyLay-up: 2 layers -54.7/+54.7 Layer thickness: 0.15 mmVf : 60%

•COMPOSITE LAMINATE – LAY UP 0-90-0 Carbon Fiber : T-300 (HR)Matrix: EpoxyLay-up: 3 layers 0-90-0 Layer thickness: 0.10 mmVf : 60%

Inserted B-Layer Eng. Meeting 3 February 2009 18

F

AXIAL TENSILE LOAD

FE MODEL CONSTRAINTS Pipe end face 1 (at X=0 mm) : all nodes

constrained UX,UY,UZ

Nodal solution - displacement vector sum Amplified scale (10) Element solution - stress along fibers in layer 1

Inserted B-Layer Eng. Meeting 3 February 2009 19

SUPPORTED PIPE DEFLECTION DUE TO GRAVITY EFFECT

Inserted B-Layer Eng. Meeting 3 February 2009 20

CANTILEVERED PIPE DEFLECTION DUE TO GRAVITY EFFECT

Inserted B-Layer Eng. Meeting 3 February 2009 21

PIPE INTERNAL PRESSURE

Pipe subjected to internal pressure and hydrostatic head pressure.

FE MODEL CONSTRAINTS Pipe end face 1 (at X=0 mm): all nodes constrained

UX,UY,UZ (see picture 19)

Inserted B-Layer Eng. Meeting 3 February 2009 22

STAVE SIMULATIONS WITH DIFFERENT MESH

THERMAL STEADY-STATE SIMULATIONS

Inserted B-Layer Eng. Meeting 3 February 2009 23

THERMAL STEADY-STATE calculation of the temperature field on the new stave with pipe cooling and power on (max heat flux from modules 7200 W/m2). Internal wall pipe temperature set to 0° C.

Mono-pipe and bi-pipe cases.

THERMAL STEADY-STATE SIMULATIONS

Inserted B-Layer Eng. Meeting 3 February 2009 24

THERMAL STEADY-STATE: temperature field on the new stave with pipe cooling and power on (max heat flux from modules 7200 W/m2). See next table for the results.

Thermal simulation with aluminum pipe - nodal temperatures resulting

Thermal simulation with carbon pipe - nodal temperatures resulting

Thermal simulation with titanium pipe - nodal temperatures resulting

Comparison between staves with different pipe materials:- Carbon fiber composite (0.3 mm)- Aluminum (0.3 mm)- Titanium (0.1 mm)

THERMAL STEADY-STATE SIMULATIONS

Inserted B-Layer Eng. Meeting 3 February 2009 25

THERMAL STEADY-STATE: temperature field on the new stave with pipe cooling and power on (max heat flux from modules 7200 W/m2). See next table for the results.

Thermal simulation with aluminum pipes - nodal temperatures resulting

Thermal simulation with carbon pipes - nodal temperatures resulting

Thermal simulation with titanium pipes - nodal temperatures resulting

Comparison between staves with different pipe materials:- Carbon fiber composite (0.3 mm)- Aluminum (0.3 mm)- Titanium (old value 0.3 mm)

THERMAL STEADY-STATE SIMULATIONS summary table

Inserted B-Layer Eng. Meeting 3 February 2009 26

27

COMPOSITE PIPE STATIC STRUCTURAL MECHANICS

PIPE 3D FE MODELPIPE ELEMENTS COORDINATE SYSTEMS FOR

LAYERED ELEMENTS ORIENTATION

The materials database which we refer for the simulations, is located at the following web address: http://dgiugni.web.cern.ch/dgiugni/upgrade/simulation/In the database are collected the known materials mechanical and thermal properties.

The materials used for the composite pipe simulations are :•Carbon fiber: T300 HR•Matrix: Epoxy, with two different CTE (70 ppm/C or 110 ppm/C)•Volume fiber ratio (Vf) : 60% (baseline) or, alternatively, 30% (*)

•(*) For the carbon pipe with lay-up [54,7 / -54,7] also have been carried out simulations with Vf = 40%, 50% and 70%,only for the calculation of the CTE.

Composite pipe CTE evaluation using a ΔT as input to derive the lengthening Vf=30%

28

Composite pipe CTE evaluation using a ΔT as input to derive the lengthening Vf=60%

29

30

- Max stress- safety factor (Tsai-Hill failure criterium)- strain (using transversal strain for tightness verification)

Ply calculation for a composite pipe with internal pressure (design pressure 150 bar)

31

Optimization of the carbon pipe

The design of the laminate of the pipe should satisfy three basic criteria:

-150 bar test pressure with minimum safety factor SF = 4

- Stay tight under pressure, transversal plies strains εT ≤ 0.1%, in order to avoid the microcracks growth

- Match the longitudinal CTE of the other materials (about -2 ppm/C for the CFRP Omega support with lay-up [0/60/-60] S2 and -0.7/+0.6 ppm/C for the carbon foam).

From the simulation results the best lay-up matching the three criteria are: [45 / -45] or [±55/±40]

THERMO-MECHANICAL SIMULATIONS

32

Constraints diagram

THERMO-MECHANICAL SIMULATIONS:

to determine the behavior (deformation and stress) of the full length stave subjected to a temperature decrement as:

1-A fixed ΔT = -60 C°

2- The nodal thermal field from the previous thermal analysis (assuming the temperature of the inner surface of the cooling pipes as 0°C).

The ΔT value of -60 C° is determined by the difference between the minimum temperature value of the cooling fluid in the pipes (-40 °C) and the environment temperature, that we assume as 20 °C.

So, having fixed to 0°C the temperature of the inner surface of the cooling pipes in the thermal analysis , we

consider 60°C the temperature of the non deformed stave FE model in the mechanical environment.

33

RESULTS EVALUATED IN THERMO-MECHANICAL SIMULATIONSWe want evaluate the following things:

-Maximum stave bow in the middle length – UZ [µm]-Maximum stave deformation – USUM [µm]-Maximum Von Mises stress in the carbon foam – SEQV [MPa]-Maximum compression stress in the carbon foam – SX [MPa]-Maximum shear stress in the carbon foam – SXY [MPa]

THERMO-MECHANICAL SIMULATIONS

34

Thermo-mechanical simulation with carbon pipe: Stave bow

Thermo-mechanical simulation with carbon pipe: carbon foam

Von Mises stress

Thermo-mechanical simulation of the stave with one carbon pipe

THERMO-MECHANICAL SIMULATIONS

35

Thermo-mechanical simulation with Titanium pipe: Stave bow

Thermo-mechanical simulation with Titanium pipe: carbon foam

Von Mises stress

Thermo-mechanical simulation of the stave with one Titanium pipe

THERMO-MECHANICAL SIMULATIONS

36

Thermo-mechanical simulation with Aluminum pipe: Stave bow

Thermo-mechanical simulation of the stave with one Aluminum pipe

THERMO-MECHANICAL SIMULATIONS

37

Thermo-mechanical simulation with carbon pipes: Stave bow

Thermo-mechanical simulation with carbon pipes: carbon foam

Von Mises stress

Thermo-mechanical simulation of the stave with two carbon pipes

THERMO-MECHANICAL SIMULATIONS summary table

38

THERMO-MECHANICAL SIMULATIONS

39