5 Werkstofftechnik
Filtern
Erscheinungsjahr
- 2019 (139) (entfernen)
Dokumenttyp
- Vortrag (73)
- Posterpräsentation (31)
- Beitrag zu einem Tagungsband (19)
- Zeitschriftenartikel (7)
- Buchkapitel (2)
- Sonstiges (2)
- Forschungsbericht (2)
- Monografie (1)
- Dissertation (1)
- Forschungsdatensatz (1)
Sprache
- Englisch (108)
- Deutsch (30)
- Mehrsprachig (1)
Referierte Publikation
- nein (139) (entfernen)
Schlagworte
- Corrosion (13)
- Additive Manufacturing (12)
- Glass (11)
- Low Cycle Fatigue (8)
- Microstructure (7)
- CCS (5)
- CO2 (5)
- Carbon steel (5)
- Crack growth (5)
- Water content (5)
- Additive manufacturing (4)
- Ceramic (4)
- Degradation (4)
- EBSD (4)
- Fatigue (4)
- LCF (4)
- Mikrostruktur (4)
- Ti-6Al-4V (4)
- Transmission electron microscopy (4)
- 316L (3)
- Alloy 2618A (3)
- Anisotropy (3)
- Ceramic spring (3)
- DCB (3)
- Diffraction (3)
- Diopside (3)
- Full-Notch Creep Test (FNCT) (3)
- In situ (3)
- Modeling (3)
- Orientation (3)
- Oxidation (3)
- P92 (3)
- Pitting (3)
- Slurry (3)
- Tempered Martensite Ferritic Steels (3)
- Thermo-Mechanical Fatigue (3)
- Utilization (3)
- 3D (2)
- 3D printing (2)
- AISI 316L (2)
- Additive Fertigung (2)
- Al-Cu-Li alloys (2)
- Alterung (2)
- Aluminium (2)
- Betriebsfestigkeit (2)
- CCU (2)
- CT (2)
- Capture (2)
- Carbon (2)
- Carbon capture (2)
- Ceramics (2)
- Coarsening (2)
- Composite (2)
- Computed Tomography (2)
- Condensation (2)
- Corrosion Fatigue (2)
- Crack Propagation (2)
- Creep-Fatigue (2)
- Crevice corrosion (2)
- Crystal plasticity (2)
- Crystallization (2)
- Dehnungsfehler (2)
- Diesel (2)
- Digital material representation (2)
- Distribution function (2)
- Extensometer (2)
- FeCr- alloys (2)
- Fiber reinforced polymer (2)
- Fracture surface analysis (2)
- Fraktografie (2)
- Glas (2)
- Glass fiber reinforced polymers (2)
- High Alloyed Steel (2)
- High Temperature Testing (2)
- High temperature (2)
- High temperature corrosion (2)
- IN 718 (2)
- IR (2)
- Internal friction (2)
- Kavitation (2)
- Kleinprobenprüfung (2)
- Laminography (2)
- Layerwise (2)
- Lightweight materials (2)
- Monte-Carlo Simulation (2)
- Non-destructive testing (2)
- Photon counting detector (2)
- Pipelines (2)
- Polyethylene, PE-HD (2)
- Polymer (2)
- Polymer matrix composites (2)
- Powder (2)
- Probengrößeneffekt (2)
- Roughness (2)
- Röntgenbeugung (2)
- Röntgenrefraktion (2)
- Sandwich (2)
- Scale-bridging (2)
- Schadensanalyse (2)
- Schädigung (2)
- Selective laser melting (2)
- Simulation (2)
- Sintering (2)
- Soda-lime silicate glass (2)
- Steel (2)
- Storage (2)
- Sulfidation (2)
- Surface (2)
- Surface crystallization (2)
- Synthetic air (2)
- TMF (2)
- Temperaturschwankungen (2)
- Tensile Properties (2)
- Ti64 (2)
- TiAl5V4 (2)
- Titan (2)
- Titanium (2)
- Topografie (2)
- VSSA (2)
- Virtual experiments (2)
- Water speciation (2)
- Weibull Distribution (2)
- Werkstoffprüfung (2)
- Wind energy (2)
- Wind turbine blades (2)
- Zero-g (2)
- Zugeigenschaften (2)
- Zugversuch (2)
- µ-gravity (2)
- 3D imaging (1)
- 5G (1)
- AFM based test methods (1)
- AM (1)
- Aggressive environment (1)
- Alkali-activated materials (1)
- Analytische Zentrifuge (1)
- Anwendungen (1)
- Aquifer (1)
- Atomization (1)
- Aufbau von Festkörpern (1)
- Aussonderugnsrate (1)
- BTS (1)
- Berstdruck (1)
- Bioceramics (1)
- Blähen (1)
- Breakdown strength (1)
- Brittle fracture (1)
- Bruchflächenanalyse (1)
- CALPHAD (1)
- CALPHAD databases analysis (1)
- CCUS (1)
- CO2 Corrosion (1)
- CO2-Speicherung (1)
- CO2-storage (1)
- Calibration (1)
- Carbidic austempered ductile iron (1)
- Carbon Capture, Utilization and Storage (CCUS) (1)
- Carbon storage (1)
- Cement (1)
- Certification Standard 22 (1)
- Chemically Complex Alloy (1)
- Chemische Analyse (1)
- Chemo-mechanical coupling (1)
- Co-axial monitoring (1)
- Complex concentrated alloy (CCA) (1)
- Corrosion and storage (CCUS) technology (1)
- Corrosion resistance (1)
- Crack healing (1)
- Crack propagation (1)
- Creep (1)
- Crystal Plasticity Modelling (1)
- Crystal orientation (1)
- DED-L (1)
- Damage (1)
- Dark-field transmission electron microscopy (DFTEM) (1)
- Data storage (1)
- Deformation behavior (1)
- Dense phase (1)
- Destabilization (1)
- Dielectric strength (1)
- Dislocation (1)
- Dislocations (1)
- Distributed fiber optic sensors (1)
- Droplet (1)
- Droplet corrosion (1)
- Druckgasspeicher (1)
- Dual-energy (1)
- Ductile iron (1)
- Dynamic mechanical analysis (1)
- Dynamisch Mechanische Analyse (1)
- EASA (1)
- EIS (1)
- Early oxidation (1)
- Eigenschaften (1)
- Elastic constants (1)
- Electrochemical deposition (1)
- Electrochemical dressing (1)
- Electromicroscopy (1)
- Electron backscattered diffraction (EBSD) (1)
- Electron energy (1)
- Electropolishing (1)
- Endurance Limit (1)
- Energiespeicherung (1)
- Energy distribution (1)
- Environmental Stress Cracking (ESC) (1)
- Environmental stress cracking (1)
- Environmental stress cracking (ESC) (1)
- Ermüdung (1)
- Erneuerbare Energien (1)
- Explosionsschutz (1)
- Failure test (1)
- Faser-Kunststoff-Verbunde (1)
- Faserkunststoffverbunde (1)
- Fatigue Life Evaluation (1)
- Fiber reinforced polymers (1)
- Fine Powder (1)
- Flowability (1)
- Foaming (1)
- Focused Ion Beam (1)
- Force-distance diagram (1)
- Freeze Drying (1)
- Fresnoit (1)
- Gasdetektion (1)
- Gassensorik (1)
- Gefügeuntersuchung (1)
- Geothermal (1)
- Glass ceramic (1)
- Glass matrix composite (1)
- Glass powder (1)
- Glass screening device (1)
- Glass-ceramic (1)
- Glasspeicher (1)
- Gleichgewicht (1)
- Grünfolieneigenschaften (1)
- HDPE Soprption (1)
- HDPE Sorption (1)
- Hard machining (1)
- Hardness (1)
- Heat treatment (1)
- Heißgasextraktion (1)
- Heißgaskorrosion (1)
- High alloyed steel (1)
- High entropy alloys (1)
- High-entropy alloys (1)
- High-temperature corrosion (1)
- Hochentropielegierungen (1)
- Hochtemperaturermüdung (1)
- Honing (1)
- Honing Stone (1)
- Inconel 686 (1)
- Irregular topography (1)
- Keramikfeder (1)
- Keramische Folien (1)
- Kikuchi pattern (1)
- Korrosion (1)
- Kreislaufwirtschaft (1)
- Kriechen (1)
- Kristallisation (1)
- Kristallsystem (1)
- Kurzfaser-verstärkte Thermoplaste (1)
- LMD (1)
- LTCC multilayer (1)
- Langzeitstabilität (1)
- Laser Beam Melting (1)
- Laser Scanning Microscopy (1)
- Laser Scanning Microscopy (LSM) (1)
- Laser cladding (1)
- Laser-induced slip casting (1)
- Laserbearbeitung (1)
- Laserscanningmikroskopie (LSM) (1)
- Layer system (1)
- Layerwise Slurry Deposition (1)
- Layerwise slurry deposition (1)
- Lebensdauer (1)
- Machine Learning (1)
- Magnetic domains (1)
- Magnetische Domänen (1)
- Magnetoelastic effect (1)
- Magnetoelastischer Effekt (1)
- Material degradation (1)
- Materialkreislauf (1)
- Materialprüfung (1)
- Materials science (1)
- Mechanical behavior (1)
- Mechanical properties (1)
- Mehrachsige Verformung (1)
- Metal powder characterization (1)
- Metrology (1)
- Microhardness (1)
- Micromechanical model (1)
- Microstructure analysis (1)
- Microstructure characterisation (1)
- Microstructure evolution (1)
- Microstructure modification (1)
- Mikrostrukturuntersuchung (1)
- Mindedestberstdruck (1)
- Mini-UAV (1)
- Mixed Ca-K-Na phosphates (1)
- Modell (1)
- Mortel (1)
- Multiaxial deformation (1)
- NDT (1)
- NMR (1)
- Na and K rhenanites (1)
- Nano particle (1)
- Nano screening (1)
- Nanomaterial (1)
- Nanoparticles (1)
- New standards (1)
- Ni-Resist (1)
- Niobium alloying (1)
- Nondestructive testing (1)
- Normung (1)
- Ooxidation (1)
- Optical criterion (1)
- Particle size (1)
- Partikelgrößenverteilung (1)
- Phase diagram (1)
- Phase transformation (1)
- Phase transformations (1)
- Phase-field simulation (1)
- Physically based material model (1)
- Pipeline (1)
- Polyaniline (1)
- Polyethylen hoher Dichte (1)
- Pores (1)
- Power plant (1)
- Power-to-Gas (1)
- Process Monitoring (1)
- Process monitoring (1)
- REM (1)
- Referenzmaterial (1)
- Referenzorganismus (1)
- Referenzverfahren (1)
- Repair patch (1)
- Residual stress (1)
- Restberstfestigkeit (1)
- Risikoanalyse (1)
- Rohrprobekörper (1)
- Sailplane Development Panel (1)
- Salt melt (1)
- Sample preparation (1)
- Sandwich structures (1)
- Scanning Electron Microscopy (SEM) (1)
- Scanning electron microscopy (1)
- Semiconductor materials (1)
- Sensor (1)
- Sensorik (1)
- Silicon Carbide (1)
- Silver glass paste (1)
- Sintern (1)
- Slip-rolling (1)
- Slow Crack Growth (SCG) (1)
- Slow crack growth (1)
- Soda-lime-silica glass (1)
- Spannungs-Dehnungs-Verhalten (1)
- Spannungsriss (1)
- Spectroscopy (1)
- Spring constant (1)
- Spring constant (1)
- Stanzen (1)
- Streuung (1)
- Structural steel (1)
- Struktur (1)
- Superalloy (1)
- Supercritical CO2 (1)
- Supercritical/dense phase CO2 (1)
- TEM (1)
- Tempered martensite ferritic steel (1)
- Tempered martensite ferritic steels (1)
- Tensile testing (1)
- Thermodynamic analysis (1)
- Thermomechanics (1)
- Thermomechanik (1)
- Transmission electron microscopy (TEM) (1)
- Tribologie (1)
- Ultrasound (1)
- Ungleichgewicht (1)
- Unlegierter Baustahl (1)
- Utilization, and storage (CCUS) technology (1)
- VM12 SHC (1)
- Vacuum hot extraction (1)
- Vickers (1)
- Vickers indentation (1)
- Viskoplastisch (1)
- Wasserstoff (1)
- Wasserstofferzeugung (1)
- Werkstoffmechanische Prüfung (1)
- Wind turbine blade shells (1)
- Windenergie (1)
- XRD (1)
- Zerstörungsfreie Prüfung (1)
- Zug-Druck-Schubprüfung (1)
- alumina (1)
- arbon capture (1)
- ausfgallfreie Lastwechsel (1)
- bioactive (1)
- biomaterials (1)
- bone (1)
- carbon steel (1)
- ceramics (1)
- coarsening (1)
- condensate (1)
- corrosion (1)
- electrochemical characterization (1)
- hardness (1)
- impurities (1)
- microstructure analysis (1)
- pitting corrosion (1)
- selective laser melting (1)
- statistische Auswertung (1)
- utilization, and storage (CCUS) technology (1)
- volume resistivity (1)
Organisationseinheit der BAM
- 5 Werkstofftechnik (139)
- 5.1 Mikrostruktur Design und Degradation (38)
- 5.2 Metallische Hochtemperaturwerkstoffe (30)
- 5.4 Multimateriale Fertigungsprozesse (27)
- 5.3 Polymere Verbundwerkstoffe (21)
- 5.6 Glas (19)
- 7 Bauwerkssicherheit (18)
- 5.5 Materialmodellierung (14)
- 8 Zerstörungsfreie Prüfung (14)
- 7.6 Korrosion und Korrosionsschutz (12)
Eingeladener Vortrag
- nein (73)
The layerwise slurry deposition (LSD) has been established in the recent years as a method for the deposition of ceramic powder layers. The LSD consists in the layer-by-layer deposition of a ceramic slurry by means of a doctor blade; each layer is sequentially deposited and dried to achieve a highly packed powder layer.
The combination of binder jetting and LSD was introduced as a novel technology named LSD-print. The LSD-print takes advantage of the speed of binder jetting to print large areas, parallel to the flexibility of the LSD, which allows the deposition of highly packed powder layers with a variety of ceramic materials.
The working principle and history of the LSD technology will be shortly discussed. A theoretical background will be also discussed, highlighting advantages and drawbacks of the LSD compared to the deposition of a dry powder.
The last part of the talk will be dedicated to highlight recent results on the LSD-print of SiSiC of geometrically complex components, in collaboration between BAM and HC Starck Ceramics GmbH. Density, microstructure and mechanical properties of LSD-printed and isostatic pressed samples will be discussed and compared.
Powder bed -based technologies are amongst the most successful Additive Manufacturing (AM) techniques. "Selective laser sintering/melting" (SLS/SLM) and "binder jetting 3D printing" (3DP) especially are leading AM technologies for metals and polymers, thanks to their high productivity and scalability.
However, the flowability of the powder used in these processes is essential to achieve defect-free and densely packed powder layers. For standard powder bed AM technologies, this limits the use of many raw materials which are too fine or too cohesive.
This presentation will discuss the possibilities to either optimize the powder raw material to adapt it to the specific AM process, or to develop novel AM technologies which are able to process powders in a wider range of conditions.
In this context, the "layerwise slurry deposition" (LSD) has been developed as a layer deposition method which enables the use of very fine ceramic particles.
In powder bed Additive Manufacturing (AM) technologies, a part is produced by depositing and piling up thin powder layers. In each layer, the cross section of the object to build is defined by locally consolidating the powder, by sintering/melting the material (powder bed fusion technologies) or by ink jetting a binder (binder jetting technologies).
These are already leading AM technologies for metals and polymers, thanks to their high productivity and scalability. The application of these techniques to most ceramics has been challenging so far, because of the challenges related to the deposition of homogeneous powder layers when using fine powders.
In this context, the "layerwise slurry deposition" (LSD) has been developed as a layer deposition method which enables the use of SLS/SLM and 3DP technologies for advanced ceramic materials. LSD consists in the layer-by-layer deposition of a ceramic slurry by means of a doctor blade. Each layer is deposited and dried to achieve a highly packed powder layer. The LSD offers high flexibility in the ceramic feedstock used, especially concerning material and particle size, and enables the production of parts with physical and mechanical properties comparable to pressed or slip-casted parts. In this presentation, the LSD technique will be introduced and several examples of application to porcelain, SiC and alumina products will be reported.
Powder bed -based technologies are amongst the most successful Additive Manufacturing (AM) techniques. "Selective laser sintering/melting" (SLS/SLM) and "binder jetting 3D printing" (3DP) especially are leading AM technologies for metals and polymers, thanks to their high productivity and scalability.
However, the flowability of the powder used in these processes is essential to achieve defect-free and densely packed powder layers. For standard powder bed AM technologies, this limits the use of many raw materials which are too fine or too cohesive.
This presentation will discuss the possibilities to either optimize the powder raw material to adapt it to the specific AM process, or to develop novel AM technologies which are able to process powders in a wider range of conditions.
In this context, the "layerwise slurry deposition" (LSD) has been developed as a layer deposition method which enables the use of very fine ceramic particles. Another technology, the Gas Flow Assisted Powder Deposition, can increase the stability of the powder bed and the packing density, even in extreme conditions such as in absence of gravitational forces.
Powder bed -based technologies are amongst the most successful Additive Manufacturing (AM) techniques. "Selective laser sintering/melting" (SLS/SLM) and "binder jetting 3D printing" (3DP) especially are leading AM technologies for metals and polymers, thanks to their high productivity and scalability. In this context, the "layerwise slurry deposition" (LSD) has been developed as a layer deposition method which enables the use of SLS/SLM and 3DP technologies for advanced ceramic materials. LSD consists in the layer-by-layer deposition of a ceramic slurry by means of a doctor blade. Each layer is deposited and dried to achieve a highly packed powder layer, which can be used for SLM or for 3DP. This technique offers high flexibility in the ceramic feedstock used, especially concerning material and particle size, and is capable of producing parts with physical and mechanical properties comparable to traditionally shaped parts. In this presentation, the LSD technique will be introduced and several examples of application to porcelain, SiC and alumina products will be reported.
Spherical mesoporous bioactive glasses in the silicon dioxide (SiO2)-phosphorus pentoxide (P2O5)–calcium oxide (CaO) system with a high specific surface area of up to 300m2/g and a medium pore radius of 4 nm were synthesized by using a simple one-pot surfactant-assisted sol–gel synthesis method followed by calcination at 500–700°C. The authors were able to control the particle properties by varying synthesis parameters to achieve microscale powders with spherical morphology and a particle size of around 5–10 mm by employing one structure-directing agent. Due to a high Calcium oxide content of 33·6mol% and a phosphorus pentoxide content of 4·0mol%, the powder showed very good bioactivity up to 7 d of immersion in simulated Body fluid. The resulting microspheres are promising materials for a variety of life science applications, as further processing – for example, granulation – is unnecessary. Microspheres can be applied as materials for powder-based additive manufacturing or in stable suspensions for drug release, in bone cements or fillers.
Quality Aspects of Additively Manufactured Medical Implants - Defect Detection in Lattice Parts
(2019)
Additive Manufacturing technologies are developing fast to enable a rapid and flexible production of parts. Tailoring products to individual needs is a big advantage of this technology, which makes it of special interest for the medical device industry and the direct manufacturing of final products. Due to the fast development, standards to assure reliability of the AM process and quality of the printed products are often lacking. The EU project Metrology for Additively Manufactured Medical Implants (MetAMMI) is aiming to fill this gap by investigating alternative and cost efficient non-destructive measurement methods.
Glass strength and fatigue is limited by surface cracks. As subcritical crack growth (SCCG) is governed by ambient humidity, stress corrosion at the crack tip is widely accepted to be the underlying mechanism. However, as water is known to have decisive effect on glass properties and can rapidly enter the crack tip near glass region, SCCG could be affected by such water related phenomena. We tried to mimic these effects studying water dissolution and speciation, mechanical properties, and SCCG in water-bearing glasses. For this purpose, glasses up to 8 wt% water have been prepared by means of high-pressure melting of glass powder - water mixtures.
As part of this effort, SCCG in dry and hydrous commercial micros¬cope slide glass (CW = 6 wt%) was studied in double cantilever beam (DCB) geometry and sub-Tg relaxation was measured by Dynamic Mechanical Analysis (DMA).
For SCCG in ambient air (24% r.h.), SCCG was promoted by the presence of 6wt% bulk water with respect to the dry glass. On the other hand, stress intensity values, KI, required to cause slow crack growth (v < 10-6 ms-1) resemble literature findings for float glass of similar composition in liquid water, which might represent the maximum possible promoting effect of ambient water on SCCG.
For SCCG in vacuum (10-3 mbar), dissolved bulk water causes even more pronounced effects. Most strikingly, it strongly decreases the slope of the log v(KI)-curve, which is a measure of dissipated energy during fracture. A strong increase of sub-Tg relaxation with increasing water content was confirmed by DMA. As a consequence, slow crack growth occurs at KI values as measured in the dry glass whereas fast crack growth occurs at much larger KI than that of the dry glass. Kinks and shoulders shown by the inert log v(KI)-curve indicate that bulk water does not simply affect bulk mechanical properties.
Ambient water influences sub-critical crack growth (SCCG) from microscopic surface flaws, leading to stress corrosion at the crack tip. The complex influence of humidity accelerating slow crack propagation (region I) is well studied only for dry commercial NCS glass (< 1000 ppm water). To shed light on this influence, the effect of water is mimicked by studying SCCG water-bearing glasses. For this purpose, water-bearing silicate glasses of 8 wt% total water were synthesized at 0.5 GPa and compared to dry glasses. SCCG was measured in double cantilever beam geometry. For dry glasses, 3 trends in crack velocity vs. stress intensity, KI, curve were found. The slope in region I increases in the order NCS < NBS < BaCS < NZnS < NAS glass. The velocity range of region II, reflecting the transition between corrosion affected and inert crack growth (region III), varies within one order of magnitude among these glasses. The KI region of inert crack growth strongly scatters between 0.4 and 0.9 MPam0.5. For hydrous glasses, it is found that water strongly decreases Tg, form a new sub-Tg internal friction peak caused by molecular water, and makes the glasses more prone to SCCG. The observed trends will be discussed in terms of the effects of Youngs Modulus on the strain energy release rate and energy dissipation related to mechanical glass relaxation phenomena.
Environmental conditions are known to influence sub-critical crack growth (SCCG) that starts from microscopic flaws at the glass surface, leading to stress corrosion phenomena at the crack tip. The processes at the crack tip are complex and water has been identified as a key component governing SCCG at low crack velocities (region I). In particular, the influence of humidity accelerating crack propagation is well studied for dry industrial soda-lime silicate glasses (< 1000 ppm water). To shed light on this influence, the effect of water is mimicked by studying SCCG in water-bearing glasses. For this purpose, water-bearing silicate glasses of up to 8 wt% total water were synthesized in an internally heated pressure vessel at 0.5 GPa and compared to dry glasses. SCCG was measured using the double cantilever beam technique. For dry glasses, three trends in the crack growth velocity versus stress intensity, KI, curve were found. The slope in region I, limited by environmental corrosion, increases in the order soda-lime silicate < sodium borosilicate < barium calcium silicate < sodium zinc silicate < sodium aluminosilicate glass. The velocity range of region II, reflecting the transition between corrosion affected and inert crack growth (region III), varies within one order of magnitude among these glasses. The KI region of inert crack growth strongly scatters between 0.4 and 0.9 MPam1/2. For hydrous glasses, it is found that water strongly decreases Tg, form a new sub-Tg relaxation peak caused by molecular water, and makes the glasses more prone to SCCG. The observed trends will be discussed in terms of the effects of Youngs Modulus on strain energy release rate and energy dissipation related to glass relaxation phenomena.
Determination of Distribution Function used in MCS on Safety Analysis of Hydrogen Pressure Vessel
(2019)
The test data of static burst strength and load cycle strength of composite pressure vessels are often described by GAUSSian normal or WEIBULL distribution function to perform safety analyses. The goodness of assumed distribution function plays a significant role in the inferential statistics to predict the population properties by using limited test data. Often, GAUSSian and WEIBULL probability nets are empirical methods used to validate the distribution function; Anderson-Darling and Kolmogorov-Smirnov tests are the mostly favorable approaches for Goodness of Fit. However, the different approaches used to determine the parameters of distribution function lead mostly to different conclusions for safety assessments. In this study, six different methods are investigated to show the variations on the rates for accepting the composite pressure vessels according to GTR No. 13 life test procedure. The six methods are: a) Norm-Log based method, b) Least squares regression, c) Weighted least squares regression, d) A linear approach based on good linear unbiased estimators, e) Maximum likelihood estimation and f) The method of moments estimation. In addition, various approaches of ranking function are considered. In the study, Monte Carlo simulations are conducted to generate basic populations based on the distribution functions which are determined using different methods. Then the samples are extracted randomly from a population and evaluated to obtain acceptance rate. Here, the “populations” and “samples” are corresponding to the burst strength or load cycle strength of the pressure vessels made from composite material and a plastic liner (type 4) for the storage of hydrogen. To the end, the results are discussed, and the best reliable methods are proposed.
Determination of Distribution Function used in MCS on Safety Analysis of Hydrogen Pressure Vessel
(2019)
The test data of static burst strength and load cycle strength of composite pressure vessels are often described by GAUSSian normal or WEIBULL distribution function to perform safety analyses. The goodness of assumed distribution function plays a significant role in the inferential statistics to predict the population properties by using limited test data. Often, GAUSSian and WEIBULL probability nets are empirical methods used to validate the distribution function; Anderson-Darling and KolmogorovSmirnov tests are the mostly favorable approaches for Goodness of Fit. However, the different approaches used to determine the parameters of distribution function lead mostly to different conclusions for safety assessments. In this study, six different methods are investigated to show the variations on the rates for accepting the composite pressure vessels according to GTR No. 13 life test procedure. The six methods are: a) NormLog based method, b) Least squares regression, c) Weighted least squares regression, d) A linear approach based on good linear unbiased estimators, e) Maximum likelihood estimation and f) The method of moments estimation. In addition, various approaches of ranking function are considered. In the study, Monte Carlo simulations are conducted to generate basic populations based on the distribution functions which are determined using different methods. Then the samples are extracted randomly from a population and evaluated to obtain acceptance rate. Here, the “populations” and “samples” are corresponding to the burst strength or load cycle strength of the pressure vessels made from composite material and a plastic liner (type 4) for the storage of hydrogen. To the end, the results are discussed, and the best reliable methods are proposed.
Diese DIN SPEC legt ein Verfahren für die Prüfung von unverstärkten und partikel- und kurzfaserverstärkten Kunststoffen mittels Zug-Druck-Schubprüfung fest. Dieses Verfahren findet Anwendung zur Bestimmung der Schwingfestigkeit im Bereich von 103 bis 107 Schwingspielen und der Nachgiebigkeiten unter statischer Belastung sowie der Zugfestigkeit. Alle Beanspruchungen und berechneten Größen sind nennspannungs-basiert.
Grundsätzlich besteht bei Rohrprobekörpern auch die Möglichkeit eine Beanspruchung in Längs- und in Umfangsrichtung durch Innendruck zu erzeugen. Dies wird in dieser Spezifikation nicht berücksichtigt, um die Anwendung überschaubar zu halten. Bei Rohrproben mit ausgeprägter Querschnittsverkleinerung (z. B. der Prüfkörper Typ B), entsteht eine Umfangsspannung auch aufgrund einer Zugkraft (siehe Anhang C). Die Umfangsspannung muss dann mittels FEA lokal berechnet werden.
Das Verfahren gilt für rohrförmige Prüfkörper deren spezifische Form den Anforderungen der Werkstoff-prüfung und bei Kurzfaserverstärkung einer hohen Vorzugsausrichtung in Probenlängsrichtung genügen.
Diese DIN SPEC gilt nicht für endlosfaserverstärkte Kunststoffe. Wegen der vollkommen unterschiedlichen Fertigungstechnologien und der zu erwartenden hohen Prüflasten, sind hier die Anforderungen an die Prüfkörpergeometrie gesondert zu betrachten. Es wird nicht zielführend sein, beide Werkstoffklassen in einer Norm zu behandeln.
Der Fachbereich Mechanik der Polymerwerkstoffe befasst sich mit der Charakterisierung der mechanischen Eigenschaften und der Degradation von Polymeren und Faserverbundwerkstoffen, die in hochbeanspruchten, sicherheitsrelevanten Konstruktionen wie jenen des Flugzeugbaus, des Automobilbaus und der Windenergie-Industrie eingesetzt werden. Auch die Analyse der chemischen und physikalischen Eigenschaften von Polymeren zählt zu unserem Aufgabenbereich.
Das Spektrum reicht von der statischen Festigkeit über die Betriebsfestigkeit, die Messung bruchmechanischer und viskoelastischer Parameter bis hin zur Formulierung molekularer Schädigungsmechanismen.
Even for the basic measurements of material data for design and engineering of composite structures there is a need to upgrade standards. With a new shear frame test rig more precise values can be obtained.
With advanced methods in the research on the fatigue behaviour of FRP it was found a load level of infinite life for GFRP and CFRP. This is in the range of typical strain values of airliners and rotor blades in normal operation.
Statistically the mean time between damage events on rotor blades is 6 years (Deutscher Windenergie Report 2006). Due to imperfection in the production the shell structures get cracks after a few years fare before the designed life time. A shell test rig was built at BAM for efficient research on the effects of defects in production.
Test blades of ~10m are an efficient way for SHM research and evaluation of NDT-methods and blade geometry.
Statistically the mean time between damage events on rotor blades is 6 years (Deutscher Windenergie Report 2006). Due to imperfection in the production the shell structures get cracks after a few years fare before the designed life time. A shell test rig was built at BAM for efficient research on the effects of defects in production.
In-situ and ex-situ NDT give a better understanding from degradation processes in composite materials.
With advanced methods in the research on the fatigue behaviour of FRP it was found a load level of infinite life for GFRP and CFRP. This is in the range of typical strain values of airliners and rotor blades in normal operation.
Due to the fibre-composite nature NDT techniques have to be suitable to a wide length scale to image micro cracking as well as bigger defects. Therefore different techniques have to be applied and developed.
The common fatigue life certification of aircrafts according to the certification Standards 23 and 25 follows a building block approach. Static tests at room temperature as well in humid and high temperature conditions are done on the coupon level. Additionally, a full-scale static and fatigue test must be performed on the complete airframe (minimum on the fuselage together with the wing). For each type-certificate the complete building block approach test program must be performed.
Traditionally in Germany, the certification of sailplanes (Certification Standard 22) follows rather a family concept. A shared data base was created over the last 50 years based upon a large number of material testing. In addition to static tests at room temperature and hot-humid conditions, fatigue tests are also done on the coupon level. Additional static and fatigue tests were done on complex structures such as spar-beams, fuselages and full-scale wing structures. However, for each type-certificate, only static tests should be performed in full-scale. This concept is determined by the certification memorandum CM-S-006 “Composite Lightweight Aircraft” 2017.
The presentation was given as an introduction to the discussion about the future expectations and developments of the EASA concerning the type-certification of lightweight aircrafts according to CS22 at the OSTIVE Sailplane Development Panel Meeting at the EASA in Cologne on the 11th of October 2019.
Fiber reinforced polymers (FRPs) are a well established material in lightweight applications, e.g. in automotive, aerospace or wind energy. The FRP components are subjected to multiaxial mechanical as well as hygrothermal loads. Common operation temperatures are in the range of 213 K and 373 K (-60 °C and 100 °C) at a relative humidity of 10% to 90%. In spacecraft applications, the environmental conditions are even more extreme. However, the correlation between multiaxial mechanical loading and harsh environment conditions have to-date not been investigated in detail. The project aims to investigate the fatigue behavior of FRPs dependent on multiaxial mechanical loading, temperature, and humidity. Extensive experimental testing is performed on flat plate and cylindrical tube specimens, accompanied by numerical and analytical calculations.