end_of_studies_project_stefano_coltellacci_aerospace_engineering

Relator: Prof. R. Barboni Co-relators: Ing. G. Perrotta Ing. M. de Benedetti

Study and structural analysis of a new configuration for a

micro/nano/picosatellite dispenser for the Vega launcher

Università degli Studi di Roma "La Sapienza" Engineering

Astronautic & Aerospace Engineering Department

Student: Stefano Coltellacci

Study and structural analysis of a new configuration for a micro/nano/picosatellite dispenser for the Vega launcher Stefano Coltellacci

Summary

Trade off

Results & Conclusions

Classical and FEM Structural Analysis

Search for adequate configurations

System Analysis


Trade off between small satellite dispensers of common use on various launch systems

Dispenser for Globalstar spacecrafts on DELTA II

Dispenser for GRACE spacecrafts on Rockot

Dispenser IKAR for Globalstar spacecraft on

Soyuz TM/Fregat

Dispenser JAWSAT on Minotaur

Dispenser ASAP 5 on Ariane 5

System Analysis

Preliminary cost-effectiveness analysis

Typical payload hosted

Dual Launch Configuration (SYLDA5 on Ariane 5-like)

Payload envelope analysis


3,2 m

3,1 m

0,6 m

2,3 m

Definition of the Dual Launch System

Picosatellites inside P-POD

Nanosatellites

Microsatellites

Different vertical levels for different kind of payloads

Minisat

1.0 m

1.0 m

0.6 m


Configurations, trade off

Two final configurations

Al-built boxed structure reinforced

with column

JAWSAT-like Al-built ISOGRID structure



Configuration 1

Al-built boxed structure reinforced with CFRP column (filament winding

technique)

Configuration 2

Al-built boxed structure reinforced with CFRP column (filament winding

technique) filled with Rohacell WF 51


Configuration 3

Al-built boxed structure reinforced with CFRP sandwich column with Rohacell WF 51 core


Configuration 4

Al-built boxed structure reinforced with CFRP column (ISOGRID technique)


Configuration 5

JAWSAT-like Al-built ISOGRID structure


Weight of the dispenser structure(W)

Heritage (HER)

Flexibility of project (FP)

Capability to host a large variety of payloads (CVP)

Ability to maximize payload weight (MPW)

Availability of cots parts (COTS)

Simplicity of project (SP)

Parameters for comparison


Comparison of various configurations

W MPW CVP FP HER COTS SP

Configuration [1] 46Kg +++ ++ + ++++ ++++ ++++

Configuration [2] 54.5Kg +++ +++ +++ +++ ++++ +++

Configuration [3] 50.5Kg +++ +++ ++++ +++ ++++ +++

Configuration [4] 44.5Kg +++ ++ - + - -

Configuration [5] 75 Kg ++ ++++ - + - -


Configuration 3 winner

External boxed structure material: Al 7075-T651

CFRP sandwich column with Rohacell WF 51 foam core and 7-plies CFRP skins, Hexcell AS4C 10K

Adapter with 26-plies sym CFRP laminate, Hexcell AS4C 10K


Classical structural analysis

Wrinkling critical load

Eulerian critical load

Hand calculations of critical buckling load and comparison with inertial load in the launch

environment

Simplified approach on the most critical structural element: the

sandwich column


Launch Environment

d p z cP m m n

P=103.88 KN


Eulerian critical load

Wrinkling critical load

2

24

572

607.644

cr

cr

crcr

EIP

L

P KN

PMPa

A

2 4 222

11 12 66 222 2 2 2

212 2

548

515.85

cwr

f f c

wr

wr

E aa aD m D D D

t a b m b m t t

MPa

P KN


Compliance with Launch environment

FEM Structural Analysis


Nastran FEM Model

4053 DoF

1020 Elements

891 Nodes

CQUAD4 and CTRIA3 Elements

18 elements CONM2 spacecrafts simulating connected to the main structure with RBE2

elements Study and structural analysis of a new configuration for a micro/nano/picosatellite dispenser for the Vega launcher

Stefano Coltellacci

Static Analysis for 1g lateral accelerations and 10g longitudinals

(SOL 101)

Max Von Mises Stress

15.5 MPa@Nd 255

(Al-boxed structure)

Von Mises Stress


Interlaminar Analysis for shear stress


Ply

(Shear stress)@node

[Mpa] Ply

(Shear stress)@node

[Mpa]

1 13.6@Nd420 14 9.82@Nd1

2 13.5@Nd419 15 13.1@Nd419

3 11.3@Nd428 16 13.4@Nd420

4 11.1@Nd418 17 12.8@Nd420

5 13.6@Nd420 18 12.8@Nd420

6 13.4@Nd419 19 7.93@Nd434

7 7.9@Nd434 20 7.94@Nd434

8 7.9@Nd434 21 13@Nd419

9 13@Nd419 22 13.3@Nd420

10 13@Nd419 23 10.8@Nd418

11 13.5@Nd420 24 11.1@Nd418

12 13.2@Nd419 25 12.9@Nd419

13 8.77@Nd1 26 13.2@Nd420

Adapter



CFRP Sandwich column

Ply (Shear stress)@node

[Mpa]

1 3.72@Nd15

2 3.76@Nd15

3 3.41@Nd46407

4 3.59@Nd46319

5 3.62@Nd15

6 3.66@Nd15

7 4.7@Nd15

(CORE) 8 0.0482@Nd111

9 7.02@Nd11332

10 10.6@Nd14050

11 10.6@Nd14050

12 10@Nd14050

13 9.69@Nd14050

14 11.2@Nd14050

15 11.2@Nd14050



Hoffman Failure Indices

Element Fail. Th. Ply Failure Index

481 HOFFMAN 18 0,0153

482 HOFFMAN 9 0,0157

483 HOFFMAN 25 0,0128

485 HOFFMAN 10 0,0093

486 HOFFMAN 19 0,0163

487 HOFFMAN 8 0,0175

493 HOFFMAN 9 0,0166

494 HOFFMAN 9 0,0124

494 HOFFMAN 10 0,0124

496 HOFFMAN 19 0,0124

496 HOFFMAN 20 0,0124

Element Fail. Th. Ply Failure Index

2446 HOFFMAN 15 0,0158

3211 HOFFMAN 15 0,0154

3212 HOFFMAN 15 0,0157

3227 HOFFMAN 15 0,0103

3268 HOFFMAN 2 0,0115

3289 HOFFMAN 14 0,0182

3290 HOFFMAN 1 0,0143

3317 HOFFMAN 15 0,0229

3337 HOFFMAN 1 0,0108

3379 HOFFMAN 15 0,0174

3380 HOFFMAN 15 0,0167

CFRP Sandwich column Adapter


Modal analysis (SOL 101)

First 100 vibrational modes determination and compliance verification with launcher vibrational modes

Modal participation Mass Factors determinations to verify the “real weight” of each vibrational mode


Most significant vibrational modes

Mode Frequency (Hz) Direction

1 18,731 Tx,Rx,Ry

2 18,731 Ty,Rx,Ry

3 21,223 Rz

29 74,18916 Ty

30 74,19931 Tx

48 94,29205 Ty

49 94,29256 Tx

93 178,3847 Tz

Compliance with VEGA launcher:

1° lateral mode> 15 Hz

1° longitudinal mode> 35 Hz


Buckling Analysis (SOL 105)

First eigenvalue for Buckling made a critial buckling load of 713.1 KN

Critical stress 671 Mpa (as previded in hand calculations)


Sinusoidal vibrations analysis (SOL 108)

Mode Frequency (Hz) Direction Stress [Mpa]

1 18,731 Tx,Rx,Ry 63.8@Nd421x18Hz

2 18,731 Ty,Rx,Ry 172@Nd421x19Hz

3 21,223 Rz 33.2@Nd421x20Hz

17.3@Nd421x21Hz

29 74,18916 Ty 49.3@Nd7646x73Hz

30 74,19931 Tx 324@Nd7646x74Hz

48 94,29205 Ty 40.3@Nd35x93Hz

49 94,29256 Tx 373@Nd200x94Hz

33.4@Nd33368x95Hz

Von Mises Stress


Most stressed nodes analysis

Displacements


Von Mises Stress


Most stressed nodes analysis


94 Hz structure “breathing” mode

…we have a problem!

Waiver to limitate displacements

CFRP ribs inside the sandwich column in the most displaced locations


CFRP ribs inside the sandwich column in the most displaced locations

Most stressed nodes analysis, waiver

Displacements


More acceptable values

Von Mises Stress


Most stressed nodes analysis, waiver

More acceptable values

Random analysis (SOL 111)


Analisi RMS

RMS Analysis Tx NASTRAN output

Total Displacements [m] 6.84E-5m@Nd8494

Von Mises Stress[Mpa] 0.39Mpa@Nd8648

Total accelerations [g] 24.9g@Nd622

RMS Analysis Ty NASTRAN output




RMS Analysis Tz NASTRAN output





PSD determination as a payload input (MSC RANDOM)


GRMS Y value GRMS Z value

Microsatellite 2.577GRMS@Nd655 5.751GRMS@Nd655

Nanosatellite “low” 3.095GRMS@Nd669 7.43GRMS@Nd669

Nanosatellite “high” 3.59GRMS@Nd664 7.806GRMS@Nd664

P-POD 5.577GRMS@Nd670 7.982GRMS@Nd670


PSD determination as a payload input (MSC RANDOM)

Results & Conclusions

The mechanical model verified the first compliance of structural I/F requirements in the launch environment for the VEGA launcher

Next steps, structural tests on a sandwich column to update the FEM model for a non-linear analysis

After a long tradeoff, this study proposes a simple structure for a dispenser realized with COTS materials


end_of_studies_project_stefano_coltellacci_aerospace_engineering

Documents

new configuration

fem structural analysis

isogrid structure study

system analysis preliminary

analysis typical payload

dispenser structurew

rockot dispenser ikar

minotaur dispenser asap