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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
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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
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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)
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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
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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)
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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
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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)
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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)
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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
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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
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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)
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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)
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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
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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
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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
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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
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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
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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
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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
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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]
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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
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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)
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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
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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)
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