Design & Analysis of a Star Sensor Bracket

  • Design and analysis of a ceramic (HB-Cesic®) star sensor bracket for Meteosat Third Generation Satellite
  • Design optimization for mass minimization and minimization of thermo-elastic deformations
  • Performance of all FE analyses and verifications for the qualification of the sensor bracket:
    • Quasistatic analyses
    • Modal analyses
    • Sinus- and random vibration analyses
    • Thermale analyses
    • Thermo-elastic analyses
  • Planning and performance of all qualifikationstests

Vibration Tests for Star Sensor Bracket

  • Planning, performance and evaluation of vibration tests for ceramic (HB-Cesic®) star sensor bracket for Meteosat Third Generation Satellite
  • Performance of qualification as well as acceptance testing for flight models
  • Sine and random vibration tests
  • Experimental approximation of interface loads (forces/moments) based on a reduced mass matrix (Guyan reduction of FE model to the acceleration sensor positions) and the measured accelerations for sine as well as random vibration tests (mass operator method, see ECSS-E-HB-32-26A)
  • Computation and verification of notching profiles based on the approximated interface loads (see above) for sine and random vibration tests
  • Corellation of test results with FE analyis results

 

Measurement of the CTE of CFRP struts with integral and Invar end fitting

  • Design and assembly of a test setup for the measurement of thermal elongation of CFRP struts for extreme thermoelastic stability requirements
  • Screwed and clevis end fittings made of CFRP and Invar (reference) have been investigated
  • The test rig consists of:
    • Clearceram sensor and specimen support
    • capacitive sensors for cryogenic environment
    • TV chamber
  • In total 12 struts have been measured in the temperature range of -180°C to +70°C
  • The low CTE of the integral CFRP struts has been demonstrated

 

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FEM analyses of the waveguides for MetOp-SG (Meteorological Operational Satellite - Second Generation)

  • Structural integrity assessment of the waveguide system on MetOp-SG Satellite via FEM (Nastran)
  • Setup of a beam model for global deformations and global modal analyses
  • Calculation of the mounting bracket’s and connection’s stiffness by means of shell and solid models as input for the global model
  • Setup of a detailed shell model with shell-solid coupling of a typical waveguide section which will be subjected to vibration testing
  • Test prediction for vibration test model: modal, sine, random and quasi-static loads (QSL)

 

Functional and life tests of the ExoMars Crushing Station at Mars environmental conditions

  • In the scope of the ExoMars 2020 Mission soil samples are drilled, crushed and analyzed.
  • KRP performed life tests at Mars atmosphere (7mbar nitrogen).
  • Various types of drill samples have been crushed at temperatures down to -60°C.
  • Cameras have been installed into the thermal-vacuum chamber to monitor the sample handling and crushing process.

 

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Thermal-vacuum tests of BepiColombo MPO and MTM solar array coupons

  • Thermal-vacuum qualification testing with electrical measurements of several coupons of the BepiColombo solar array
  • Outgassing measurement with molecular witness plates at the chambers cold trap
  • Installation and test performance under cleanroom conditions
  • Temperture extremes: -170°C and +220°C
  • Vacuum: 1e-6mbar

 

Shock and Vibration Analysis and Measurements on ExoMars Components

  • The shock produced by activation of a Frangi-Bolt is measured and the SRS is directly analyzed on site (OHB premises).
  • The resulting shock loads for neighboring components have been  derived by similarity-heritage-extrapolation, following the methods proposed by ESA
    • SRS ratio method
    • Zoning procedure
    • Test prediction based on modal properties derived by FEA
  • KRP has further proposed shock attenuation solutions for this project
  • For a different ExoMars component, vibration measurements were performed (at SGS). Two kinds of tests were done:
    • Resonance search
    • Identification of optimum operational frequency with respect to function (high vibration at a selected position) and shock loads (low SRS at the interface)

 

 

Tensile Test for Notched HB-Cesic Specimens

  • Determination of the effect of v-notches on the strength of HB-Cesic
  • Derivation of characteristic notch factors for the design of thermo-stable srtructures with HB-Cesic
 
 

Determination of Material Properties of Additive Layer Manufacturing Aluminium and Titanium Alloy Specimens at Low Temperatures

  • additive layer manufacturing (ALM) as e.g. laser melting offer an outstanding design freedom and thus a huge potential for optimised lightweight structures
  • the small lot sizes typical for space applications enable the application of this manufacturing method also with respect to economical aspects
  • the achieved material properties depend on various process parameters as well as orientation of the respective part during manufacturing
  • for evaluating the material properties, the following test are performed:
    • tensile tests
    • compression tests
    • shear tests
    • pin bearing tests
  • the tests are performed for selected temperatures from room temperatures (RT) down to 4K (liquid Helium, LHe)

 

tensile test specimen installation

 ECM

Development of a Reference Platform for High Accuracy Thermal Deformation Measurements

  • the experimental verification of thermo-elastic stable structures requires a reference platform, which features a significantly higher thermo-elastic stability than the object to be measured
  • to reduce potential measurement errors due to the inherent thermal deformation of the measurement platform itself as much as possible, it is required to use 
    • ULE (ultra-low expansion) materials as Clearceram or Zerodur
    • capacitive sensors with very low thermal drift
  • tests of the developed measurement platform show a thermal stability with respect to the rotations of selected reference surfaces of  <0,1 µrad/K
 Clearceram thermoelastic deformation measurement rig www.jpg
ECM

Thermal Vacuum and Thermal Balance Testing for a Highly Stable Star-Sensor-Bracket

  • thermal vacuum cycling as well as thermal balance were performed for a ceramic (HB-Cesic®) support structure for star sensors
  • a major element for the test set-up for the thermal balance test was to establish radiative boundary conditions which match the operational conditions as close as possible with respect the applied multi-layer insulation (MLI)
  • the test has been accompanied by respective thermal FEM simulations

 Star Sensor Assembly Bracket TB Test

Star Sensor Assembly Bracket TB Test 2

OHB

Thermal-Vacuum and Vibration Testing of the EnMAP Field Splitters Under High Cleanliness Requirements

  • optical components like the micro-scale double-slit of the EnMAP Field Splitter, which resides in the focus of the telescope, require the highest level of particulate and molecular cleanliness
  • in order to ensure these cleanliness requirements during testing, a special vacuum-tight testbox has been developed

CCTB

FSSA EQM Vibration

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Functional Testing of a Hold-Down-Mechanism under Thermal-Vacuum Conditions

  • the investigated Hold-Down-Mechanism features several springs that serves as actuation elements
  • the spring forces have to be sufficiently high to overcome the friction forces during release
  • for verification, the respective spring is removed and the respective actuation force  of this spring is substituted by an external load introduction; the external force is measured
  • the required external force, which is necessary for the actuation, is compared with the force provided by this spring
  • the ratio between the required force and the available spring force provides a safety factor for the actuation by the respective spring
  • this safety factor has been determined for all springs with a special designed test set-up at -95°C in a thermal vacuum chamber

 FSSA_force_margin_TV_CAD

LSRU_force_margin_measurement_under_TV

 OHB
Shock Testing of a Microstructured Ceramic Optical Component

  • the survival of shock loads induced by stage separation or release mechanisms is mainly verified by experiments
  • especially critical for shock loads are components from brittle materials
  • for this test,  a micro-structured silicon part has been investigated, which is the critical element of an optical component
  • to reproduce the correct dynamic boundary conditions, the part of the component, which was not included in the test, has been substituted by a stiffness dummy (picture top, left), which has been developed by KRP-M
  • the shock tests have been performed on a mechanical impact device (KRP-M shock bench)
  • during testing, the correct application of the specified shock response spectrum (SRS) has been verified
  • furthermore, losses at  the mechanical connections have been evaluated

 FSSA_SA_shock_FEM

FSSA_SA_shock_test_setup

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Multi-Axis Force- and Moment-Load Test of a Hold Down Mechanism During Launch Phase

  • hold down mechanism are used for the fixation of movable subsystems of a satellite during the launch phase
  • the inertia forces caused by the launch are supported by the mechanism instead of the potentially sensitive subsystem
  • in the investigated application, the mechanism has to cope with seven different combinations of axial and lateral forces and moments
  • in addition to the mechanical stability, also the functionality of load transferring frictional connections was investigated
  • for the realisation of the seven load combinations in a standard tensile testing machine, a complex load introduction element has been designed
  • using appropriately positioned and oriented pulleys, the required rope forces were applied to the load introduction element to achieve the specified load combination
  • the correct application of the force and moment combinations has been verified by a 6-axis load cell

 LSRU_load_cases

Multi Loadcase load introduction bracket

FSSA_DTMA_Test_Setup

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Thermo-Elastic Deformation Measurement of a Autoclave Set-Up for the Manufacturing of Solar Generator Panels

  • for certain applications, high shape accuracy is required for composite- and sandwich parts
  • the shape accuracy is mainly determined by the manufacturing process and the lay-up of the laminate
  • for measuring and minimisation of manufacturing induced deformations of the Bepi Colombo solar generator, a special measurement tool has been developed, manufactured and operated
  • with this tool, the thermo-elastic deformations of the autoclave set-up were measured
  • due to the use of materials with low thermal coefficient of expansion and the application of special sensors, the tool features an excellent thermo-elastic stability and thus a high measurement accuracy

 Sun_Passing_Test_Setup_CAD

FSSA_CCTB_Sun_Passing_Test_Setup

 

Thermo-Elastic Deformation Measurement of Autoclave Structure for Manufacturing of Solar Panels

  • space applications often require high shape accuracy for composite and sandwich parts
  • the shape accuracy is significantly determined by the manufacturing process
  • for the measurement and minimization of manufacturing related deformations of the BepiColombo solar panel, a special measurement device has been developed, manufactured and comissioned
  • with this device, the thermo-elastic deformations of the autoclave structure has been measured
  • the measurement device achieves a high measurement accuracy by the use of materials with very low coefficient of thermal expansion

 

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Experimental Determination of Tilting Moment for a Pre-Tensioned Hold-Down-Stack of the BepiColombo Solar Generator

  • the four panels of the Bepi Colombo solar generator are held down during launch by pretensioned stack of bushings at several positions
  • the tilting moment caused by the launch shall not result in an opening/tilting of the pretensioned bushings
  • the critical bending moments, which results in a tilting of the bushings and thus a reduction of the overall stiffness of the bushing stack, was determined by a special designed test set-up
  • the critical moment was determined by evaluating the two linear section of the load-deflection curve prior and after the tilting
  • the tilting moment was applied by a specially designed rope mechanism and the rope force was measured by two load cells
  • the following sensors were applied to measure the deformation of the stack and the tilting of the individual bushings:
    • photogrammetry
    • inductive displacement sensor
    • gapping extensometer
    • strain gauges

HDRM canting test setup CAD iso

HDRM canting test setup

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Performance of Cryogenic Tensile Tests at 20K for Aluminium Alloy for the Ariane Launcher

  • design of der specimen geometry and manufacturing of specimens from provided raw material
  • application of cryo capable strain gauges
  • pre-tests at room temperature and 77K (LN2)
  • test performance at 20K in liquid Helium (LHe) in a cryostat
 LHe_tensile_test_setup_CAD
 OHB

Structural-Mechanical and Thermal FEM Analysis of the EnMAP Calibration Unit

  • the On Board Calibration Assembly (OBCA) provides the calibration of the spectrometer during operation
  • several lamps and LEDs are combined in order to achieve the required spectrum through an Ulbricht sphere
  • structural-mechanical analyses and optimisation have been performed:
    • quasi static analysis
    • modal analysis (resulting in a design modification for increasing stiffness)
    • random vibration analysis (including notching)
    • thermo-mechanical analysis (deformation and stress)
    • thermal analyses:
      • verification of temperature stability of lamps and LEDs for guaranteeing a constant spectrum during calibration
      • development of a method for modelling the correct thermal radiation of Halogen lamps and LEDs
      • investigation of different calibration profiles with transient thermal analyses

 obca_structural_4th_eigenmode300

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Performance of Cryogenic Tensile Tests at 77K for Aluminium Specimens for the Ariane Launcher

  • manufacturing of specimens from original ring segments of the launcher
  • design and manufacturing of customer specific specimen support with special attention to a moment free load introduction
  • application of cryo compatible strain gauges
  • test performance at 77K in liquid nitrogen (LN2)

 77K_tensile_test_setup

 OHB

Evaluation of the Effectivity of the Vibration- and Shock Generation Mechanism of the Exomars Grinder

  • measurement of the impact of the impact mechanism which is used for the cleaning of the grinder
  • selection of appropriate measurement locations and evaluation criteria
  • application of four 3-axis and single axis shock sensors
  • measurement of accelerations in dependence of impact intensity
  • evaluation of visco-elastic washers for the reduction of the shock spectrum
 Shock_Measurement_Exomars_Crushing_Station
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Shock Measurement for a Non Explosive Release Mechanism (NEA)

  • mounting of the release mechanism on a elastically supported, representative Aluminium-sandwich plate
  • determination of the shock response spectrum (SRS) in three directions and 4 locations
  • measurement of the release shock in dependence on the pretension of the release mechanism
  • computation of SRS and comparison with reference spectrum

 NEA_shocktest

NEA_shocktest_SRS_results

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Performance of Flatwise Tensile Tests at 206°C for Sandwich Substrate Specimens for Bepi Colombo Solar Generators

  • test performance according to customer specific procedure (based on ASTM C297 / C297M – 04)
  • bonding of load introduction elements to the sandwich specimens
  • ensuring of a moment-free load introduction
  • test performance at 260°C in inert gas atmosphere
  • characterisation of failure mode (adhesive failure / core failure)
 Bepi_Colombo_Flatwise_Tensile_Test
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Performance of 4 Point Bending Tests for Sandwich Substrate Specimens for Bepi Colombo Solar Generators

  • test performance according to customer specific procedure (based on ASTM D6272 – 10)
  • application of strain gauges
  • load test until failure
  • testing of pre-damaged specimens (thermal vacuum cycling between -154°C and +195°C)
 Bepi_Colombo_CFRP_Sandwich_4_point_bending_test
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Performance of Shear Tests for Sandwich Substrate Specimens for the Bepi Colombo Solar Generators

  • test performance according to ASTM 273/C273M-07
  • manufacturing of load introduction elements and subsequent bonding to the CFRP face sheets of the sandwich specimens
  • test of nominal specimens
  • test of specimens with split core bonded by core splice adhesives
 Bepi_Colombo_Core_Shear_Setup_and_Sample_after_test
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Qualification of CFRP Elements of Bepi Colombo Solar Generators at Temperatures up to 260°C

  • design of a test set-up for moment loads on the interface of three different structural elements
  • consideration of different thermal expansions for the design of the load introduction element (decoupled connection of several load introduction locations)
  • customer specific modification of a thermal chamber for tempering in inert gas conditions up to 260°C
  • application of high temperature strain gauges
  • visual inspection
  • load testing until failure
  • localisation and characterisation of the failure

 Bepi_Colombo_Yoke_IF_Test_Setup_CAD

Bepi_Colombo_Yoke_IF_Sample

OHB

Qualification of Optical Coatings

  • qualification tests of optical coatings for the EnMAP double slit component
  • characterisation and verification of optical properties before and after environmental tests:
    • BRDF (bi-directional reflectance distribution function)
    • reflectivity
    • absorbance
  • environmental tests: thermal vacuum cycling
  • adhesion testing before and after environmental testing
 FSSA_coating_TV_Test
OHB

Performance of Micro-Vibration-Tests for a Mirror System on an Optical Bench

  • Microvibrations play an increasingly important role in the design of space based optical instruments as e.g. the optical bench of an earth observation satellite
  • perturbations caused by reaction wheels or cryo-cooler exert dynamic forces on opto-mechanical structures in the sub-Newton range
  • the resulting oscillations of mirrors produce dynamic variations of the Line-Of-Sight and thus a structure-optics interaction
  • especially perturbations close to the eigenfrequencies of the optical structure can result in LOS variation reaching pixel size on the detector and thus in a degradation of image quality
  • for the investigation of the effects of micro-vibrations on optical structure, a generic test set-up has been developed and manufactured in collaboration with OHB Space Systems Munich (formerly Kayser-Threde GmbH):
    • an optical bench with mirror supports, mirrors and representative bi-pod supports
    • a base plate as substitute for the interface to the satellite bus structure
    • a reference measurement plate for providing the reference beam (HeNe-Laser) and the measurement of the resulting LOS deviations using Position Sensitive Devices (PSD, optical position sensor)
    • highly sensitive acceleration sensors mounted to the optical and mechanical components
    • 5N-Inertial actuator for the micro-vibration excitation
  • for verifying the opto-mechanical characteristics of the test set-up determined in FEM simulations, various tests have been performed:
    • static LOS test
    • experimental modal analysis using a laser vibrometer
    • micro-vibration tests for the determination of the transfer functions:
      • evaluation of the linearity with respect to excitation amplitude
      • determination of vibration energy loss / damping at the connections between components
      • evaluation of the accuracy of FEM simulations

 micro_vibrations_sensors positions

microvibration_FEM_modal_analysis

microvibration_laservibrometer

micro_vibration_actuator

 OHB

High Shock Load Testing of Electronics Box

  • electronics boxes, which are directly mounted to the launcher structure (e.g. for video processing), experience high shock loads during launch and stage separation
  • the required high shock levels often cannot be achieved using standard vibration test equipment like electrodynamic shaker
  • shock tests using mechanical impact devices as e.g. a shock bench are an economical alternative to pyrotechnical shock tests
  • a mechanical impact device, which achieves the very high shock loads  required for this application scenario of electronics boxes, was developed, manufactured, and commissioned
  • in addition to standard shock load proof tests, the sliding of bolted connections during shock events has been investigated

 OCAM2_shocktest_impact

High_Shock_Test_SRS

 OHB

EnMAP-Subsystem Management of the Opto-Mechanical Component "Field Splitter Slit Assembly (FSSA)"

  • the FSSA is a micro-scale optical component whose key elements are two parallel slits ( 24mm x 24µm each) and a micro mirror
  • the FSSA is a component that has to be positioned in the focal plane of the telescope with very high precision
  • the structuring of the slits is performed by silicon etching processes
  • the micro-mirror, opto-mechanical components are joined by complex bonding processes with high precision
  • for achieving the thermo-mechanical stability as well as contour accuracy,
    • the design and material selection was optimised,
    • and FEM simulations of the critical load cases were performed
  • the FSSA, the applied materials and surfaces have been qualified with respect to mechanical and optical properties in complex experimental investigations with various environmental conditions

 FSSA_in_EnMAP

FSSA_FEM

OHB

Shock Test on a Shock Isolation Stage for Electronics Boxes

  • performance of shock tests for the determination and optimisation of the damping properties based on the shock response spectrum (SRS)
  • measurement of the shock levels by shock accelerometers (20.000g) with a sampling rate of 200 kHz
  • calculation of the shock response spectra and evaluation of the performance of the shock dampers (STOP-CHOC ®) and the screwed connection
  • application of shock loads up to 24.000g (SRS) by mechanical impact device

Schocktest Daempfer Elektronikbox KT Test Setup.jpgSchocktest Daempfer Elektronikbox KT SRS Schockdaempfung.png

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Bepi Colombo- CTE-Measurements of a C/SiC Tube

  • development of a test device for measuring the coefficient of thermal expansion (CTE) of a C/SiC tube (carbon fiber reinforced silicon carbide, structural element of the high gain antenna of the Bepi Colombo mission)
  • determination of the CTE under vacuum conditions in a temperature range from -180°C up to max. 500°C
  • accuracy of the CTE measurement: 1E-9 to 1E-8 [1/K]

Laser Dilatometer Test Setup.jpg

Zerodur Reference and CSiC Specimen.jpg

Selex Galileo.jpg

Design Study for a CFRP Optical Bench

  • concept study for a CFRP optical bench for an Italian scientific satellite
  • investigations of various low CTE carbon fibres and cyanate ester resins
  • evaluation of moisture expansion and minimisation by a moisture barrier
CFRP_optical_bench_thermomechanical_FEM.jpg

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ESA_100.png

Bepi Colombo Solar Coupon - Phoenix

  • development tests of solar generator sample for the Bepi-Colombo mission
  • thermal vacuum tests
  • thermal cycling: +230°C to -150°C
  • functional tests in thermal vacuum conditions ( e.g. electric tests)

 

BepiColombo_Phoenix2.png
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Low Shock Release Unit (LSRU) Thermal Vacuum Functional Test

  • development test for evaluation of release time of the LSRU at extreme temperatures
  • integration of LSRU in the KRP thermal-vacuum chamber
  • electrical release
  • determination of release time and electric current consumption of the solenoid actuator
  • performance of thermal cycling in vacuum conditions
  • temperature range: -95°C / +120°C
LSRU_TV_Test.jpgLSRU_TV_Test_1.jpg

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Low Shock Release Unit Qualification Testing

  • space-qualification tests for the 16- and 33KN Low Shock Release Units
  • tests :
    • static proof-load test
    • determination of shock-load
    • functional tests for release at room temperature and at thermal-vacuum conditions
    • thermal cycling tests
    • vibration tests (sinus and random excitation)
 
LSRU_Projekt3.png