Heinz Voggenreiter

• German Aerospace Center (DLR)

3D printing has been increasingly used in aeronautical and automotive industry for the production of integral metallic or fibre-reinforced plastic (FRP) parts. Various additive manufacturing methods have been developed to respond to the growing industrial needs. The Screw Extrusion Additive Manufacturing (SEAM) is a pellet-based production techniqu...

The production costs of aircraft primary structures made of carbon fibre reinforced polymer (CFRP) are significantly higher than for comparable metal-based structures. Today substantial effort is made to achieve a sufficient reproducibility and parts’ quality in manufacturing processes of CFRP structures. Especially the sub process vacuum bagging f...

The reliable strain rate-dependent material properties at intermediate strain rate levels (1-200 s-1) are crucial for an accurate crashworthy design of fibre-reinforced polymer (FRP) composite structures. However, the presence of unacceptable oscillations in measured force signals hinders the precise identification of the dynamic mechanical respons...

Zusammenfassung Aufgrund steigender Anforderungen steht das Design von Flugzeugkabinen vor revolutionären Herausforderun-gen. Die Integration innovativer Konzepte und nachhaltiger Materialien bietet einen wichtigen Lösungsansatz. Entsprechend müssen die Entwicklung und Demonstration neuer nachhaltiger multifunktionaler Materialien, die als thermisc...

This paper presents a probabilistic micromechanics-based approach to simulate the influence of scatter sources in composite materials as an alternative to deterministic approaches. Focus is given to the effect of microscopic and macroscopic voids, material inhomogeneity induced by manufacturing processes and stochastic fibre patterns on the mechani...

Aufgrund steigender Anforderungen steht das Design von Flugzeugkabinen vor revolutionären Herausforderungen. Die Integration innovativer Konzepte und nachhaltiger Materialien bietet einen wichtigen Lösungsansatz. Entsprechend müssen die Entwicklung und Demonstration neuer nachhaltiger multifunktionaler Materialien, die als thermische und akustische...

This paper presents an experimental investigation on the intralaminar fibre-dominated fracture of unidirectional (UD) IM7/8552 carbon-epoxy composites, loaded under quasi-static (QS) and intermediate strain rates (IR). Dynamic tensile testing is carried out using a previously proposed test methodology involving a high-speed servo-hydraulic test mac...

The finite element (FE) simulation of industrial size composite structures under crush loading is a challenging task. Currently, the vast majority of these simulations employ non-physical “tweaking” parameters that are undesirable and limit the confidence in their predictive capabilities. This paper investigates three different material models base...

This paper reports experimental investigations of 3D woven carbon/epoxy composites on quasi-static and dynamic tensile properties in the longitudinal (warp) and transverse (weft) directions. Firstly, quasi-static tests were conducted to determine a baseline tensile strength and to find out the adequate specimen geometry required for dynamic testing...

Composite materials have brought new development and sizing possibilities for structural components in transportation systems. Their high specific material properties are enabling weight reduction while increasing structural performance. On the downside, composite materials are generally related to high material and manufacturing costs and increase...

Carbon fibre reinforced polymer (CFRP) materials are widely used in transport aircraft. Crashworthiness requirements demand sufficient energy absorption capacity, especially in the fuselage structure. In a recently-proposed approach, specifically-designed “tension absorber” joints utilize tension loads for energy absorption via progressive bearing...

Fiber composite materials are becoming increasingly popular in many areas of industry. The combination of high specific strength and stiffness combined with low density makes this material combination an excellent candidate for all possible applications. However, there are still many unexplored influences, especially in the field of automated produ...

The design of composite transportation structures with improved crashworthiness behaviour requires a reliable and accurate dynamic material characterisation database covering various loading rates expected in crash events. For vehicle crash scenarios experimental results at strain rates up to 200 s-1 are particularly important. However, conducting...

Governments and policy makers put pressure on a variety of industries to comply environmental regulatory mandates, and alleviate the climate changes. For example, ‘FlightPath 2050’ from the Advisory Council for Aviation Research and Innovation in Europe (ACARE) sets ambitious goals on reducing CO2 and other emissions levels to mitigate environmenta...

Dynamic properties at intermediate strain rate are inherently difficult due to the dynamic interactions between the test specimen and the test machine. These effects obscure the interpretation of test results and therefore can make the derivation of the material properties difficult and unprecise. Soft materials can be used within load introduction...

The forward faced components of passenger aircraft and large helicopters need to be certified for their performance under bird-strike loading. In bird-strike conditions the load is transferred via a perpendicular or oblique (blunt impact), a nose (splitting) or a rotating blade (slicing) surface, dependent on the position on and orientation of the...

High velocity impact on composite aircraft structures leads to the formation of flexural waves that can cause severe damage to the structure. Damage and failure can occur within the plies and/or in the resin rich interface layers between adjacent plies. In the present paper a modelling methodology is documented that captures intra- and inter-lamina...

The paper discusses a high velocity impact scenario where representative fuselage composite plates are statically preloaded and then impacted with a blunt impactor at velocities in the range 70 - 105 m/s. Compression and tension preloads that represent design limit load were considered as well as lower preloads that a structure would carry more fre...

Bird strike certification relies on testing with real birds being impacted on affected zones of airframes. However, it is known that real bird testing lacks repeatability and has an unknown species’ influence. To overcome these detrimental effects, substitute birds have been developed for many years. They replicate the bird’s tissue and their shape...

New aircraft fuselage concepts have to prove equivalent crashworthiness standards compared to conventional metallic fuselages for certification. Brittle failure mechanisms of CFRP structures make the verification of equivalent crashworthiness for novel CFRP fuselage concepts challenging since conventional metal fuselages absorb a significant part o...

The present study demonstrated the feasibility of producing carbon-based green bodies by means of extrusion,pyrolysis and subsequent conversion to C-SiSiC ceramics according to the LSI process.A thermoplastic binder system was used for the development of feedstocks that differ from conventional duroplastic binder systems as these would have created...

Nozzle extensions made of ceramic matrix composites (CMC) have the potential to improve the performance of liquid fueled rocket engines. Gas permeability and delamination have been reported to be still critical aspects in the manufacture of CMC nozzle structures. This work shows the development and manufacture of a radiation cooled C/C-SiC nozzle f...

The European aircraft industry has strong interest in novel structural concepts for future aircraft fuselage with lower fabrication costs and high performance. A critical safety issue for the design of aircraft structure is vulnerability and damage tolerance due to foreign object impact. This paper focuses on the improvement of modelling techniques...

Non-oxide ceramic matrix composites (CMCs) based on silicon carbide fibers (Tyranno SA3; UBE Industries Ltd., Japan) were manufactured via PIP-process using a polysilazane precursor. Prior to PIP-process, SiC-fabrics (two fabric types: PSA-S17I16PX and PSA-S17F08PX) were coated with oxidation resistant monazite (LaPO4) which was derived from rhabdo...

Aircraft structures are vulnerable to impacting projectiles like runway debris, birds or hail. With the increased application of composite materials in aircrafts, improving the high velocity impact (HVI) response of reinforced polymers has been a topic of research for the last decades. Only a limited number of authors investigated the effect of the...

Faserverstärkte Keramiken (CMC) zeichnen sich durch ihre Hochtemperaturbeständigkeit und hohe Schadenstoleranz aus und sind im Unterschied zu monolithischen Keramiken zur Herstellung großflächiger, dünner Leichtbaustrukturen für Hochtemperaturanwendung geeignet. Am Beispiel des C/C-SiC-Werkstoffs des DLR soll für unterschiedliche Belastungsrichtung...

This paper deals with experimental investigations on the dynamic failure behaviour of generic carbon fibre reinforced plastic (CFRP) components subjected to axial crushing, which have been developed for energy absorption in a transport aircraft structure. Several material and design parameters of the crash component as well as its interaction with...

Crashworthiness research for transport aircraft fuselage structures is important particularly with regard to the increasing ratio of carbon fibre reinforced plastic (CFRP) in primary structures. Although today’s aluminium fuselage structures offer sufficient crashworthiness purely due to the ductile behaviour of metal, the brittle behaviour of a CF...

The interlaminar energy release rates of carbon fibre reinforced SiC, were determined experimentally under mode I and II loading. The investigated CMC-material was produced from carbon fabrics by liquid silicon infiltration process. The interlaminar crack propagation was investigated on artificially pre-cracked samples. The cracks were orientated p...

Carbon-carbon silicon carbide (C/C-SiC) composite plates were manufactured based on triaxial and biaxial braided fiber preforms. The liquid silicon infiltration (LSI) method was used to achieve the SiC matrix. In a first processing step intermediate modulus carbon fiber (T800 12k) preforms were manufactured via braiding technique in ±45° and ±75° f...

Die jetzt schon hohe Leistungsdichte von Triebwerken und der Bedarf an weiteren Optimierungen des Gesamtsystems, um zukünftigen ökonomischen und ökologischen Anforderungen gerecht zu werden, erfordert ständige Innovationen auf dem Gebiet der Werkstoffe und Bauweisen. Um die hoch gesteckten, zumeist aerodynamisch dominierten Zielsetzungen zu erreich...

Biomorphic SiSiC ceramic composites were produced by liquid silicon infiltration (LSI) process. These materials are based on activated coal (ACBC) and wood fibers (MDF). Microstructural characteristics in green-, carbon- and SiSiC-body modification were investigated by analyzing curved structures (type charcoal) and planar structures (type MDF). Th...

The tensile and bending strength of the Liquid Silicon Infiltrated (LSI) ceramic–matrix composite (CMC), C/C–SiC, were investigated in varying orientations relative to the 0°/90° woven carbon fibres. The ratio of bending to tensile strength was about 1.7–2 depending on the loading direction. The non-linear stress–strain behaviour under tensile load...

Non-oxide CMCs based on pyc-coated SiC-fibres (Tyranno SA3™) as well as novel amorphous ceramic fibres in the quaternary system Si–B–C–N (named SiBNC-fibres) were manufactured via polymer infiltration and pyrolysis process. Two different fibre architectures were applied: 0|90° unidirectional (UD) cross-ply and 0|90° plain weave fabric layer. UD cro...

The paper describes quasi-static and dynamic tests to characterise the energy absorption properties of polymer composite crash energy absorbing segment elements under axial loads. Detailed computer tomography scans of failed specimens are used to identify local compression crush failure mechanisms at the crush front. The varied crushing morphology...

The structural applications of Carbon Fibre Reinforced Plastic (CFRP) composites are gradually expanding in aerospace industry as a result of their outstanding mechanical properties such as high stiffness to weight ratio and fatigue resistance. With the increasing application, the need for understanding their mechanical behaviour and failure mechan...

The effect of interlaminar defects on stiffness and strength of 3-point bending samples is predicted by cohesive zone finite element modelling. The defect informations are extracted from micro-computer tomography analysis and transferred into 2D-FE-models. The investigated material is carbon fibre reinforced Silicon carbide, C/C-SiC.

Liquid silicon infiltrated carbon fibre reinforced SiC, has shown to be a high-potential material for thermal protection systems. The tensile and bending behaviour of the ceramic-matrix composite, C/C-SiC, were investigated in varying orientations relative to the 0/90° woven carbon fibres. The ratio of bending to tensile strength was about 1.7 to 2...

Faserverbundwerkstoffe haben den Flugzeugbau nachhaltig beeinflusst und werden auch in den nächsten Jahren einen immer größeren Stellenwert in der Konstruktion von Flugzeugstrukturen einnehmen. Neben endlosfaserverstärkten Durome-ren erreichen in den letzten Jahrzehnten neue Materialien, wie faserverstärkte Hochleistungsthermoplast-Verbundwerkstoff...

Die dringlichste Herausforderung unserer Gesellschaft ist der Erhalt unseres Wohlstands im wirtschaftlichen Wettbewerb mit anderen Nationen und unter Reduktion unserer Ressourcen – und des Energieverbrauchs. Sie mündet direkt in die Fragestellung, wie wir die Produkte unseres täglichen Lebens wirtschaftlicher und effizienter herstellen und nutzen k...

The quasi-static and fatigue behavior after impact of the TiAl alloy TNBV3B produced via three different processing routes—cast, forged and extruded—has been studied on flat and airfoil-like shaped specimens making use of ballistic impact experiments. For impacts resulting in cracks the behaviour can be described using a linear-elastic fracture mec...

The paper describes a modeling methodology using finite element analysis (FEA) to simulate the influence of preloads on the impact damage resistance of composite panels. A continuum damage mechanics material model is coded within the framework of the software package Abaqus FEA to model in-ply damage development and failure. Strength reduction due...

The need for light weight structural materials with good resistance to fatigue has led designers of aerospace industry to increasingly employ CFRP structures, when especially cyclic loading is of primary concern. The composite laminate in this study is composed of multidirectional Carbon Fiber Reinforced Plastic plies (CFRP) with varying fiber orie...

Cyclic mixed mode delamination in multidirectional composite laminates subjected to high cycle fatigue loading has been investigated by numerical simulations and cyclic mixed mode bending experiments. The numerical model includes lamina and interface elements. The description of the delamination crack growth rate is based on the cyclic degradation...

With the increasing number of composite applications in aircrafts, it is essential to supply repair concepts with respect to the material properties. In addition to the carbon fiber reinforced composites with a thermoset matrix system, other matrix systems like high-performance thermoplastics have been continuously gaining market share. In comparis...

Defects like pores and delaminations still can not be fully prevented during the manufacturing of complex Ceramic Matrix Composite (CMC) structures. With the help of modern micro Computer Tomography (CT) most of the macroscopic defects can be detected with high resolution and detection reliability. Nevertheless, the influence of defects on stiffnes...

The impact resistance of the TiAl alloy TNBV3B produced via three processing routes – cast, forged and extruded – has been studied on flat and airfoil-like shaped specimens making use of ballistic impact experiments. Several factors influencing the damage behaviour were investigated. The evolution of centre and edge impact induced damage in flat sp...

This paper focuses on the effect of fiber orientation and stacking sequence on the progressive mixed mode delamination failure in composite laminates using fracture experiments and finite element (FE) simulations. Every laminate is modelled numerically combining damageable layers with defined fiber orientations and cohesive zone interface elements,...

The impact behaviour of the TiAl alloy TNBV3B produced on three different processing routes - cast, forged (with a relatively small degree of deformation) and extruded - has been studied making use of ballistic tests. The damage evolution due to centre and edge impacts on flat and airfoil-like specimens has been investigated with a focus on the inf...

This paper analyses the progressive mixed mode delamination failure in unidirectional and multidirectional composite laminates using fracture experiments, finite element (FE) simulations and an analytical solution. The numerical model of the laminate is described as an assembly of damageable layers and bilinear interface elements subjected to mixed...

Status and future challenges in the CFRP Airframe Maintenance. The process from defect detection with structural health monitoring to computertomographie and bonded repair is described with the identified need for research.

TiAl alloys show a low ductility, which limits their application especially in components prone to impact damage like turbine blades or vanes. Therefore, the influence of high-speed impact damage on the mechanical behaviour of a cast and a forged version of the intermetallic TiAl alloy TNBV3B has been investigated. Ballistic tests were performed w...

Gehört der Metallrumpf, mit dem im Moment noch alle Flugzeuge gefertigt werden, schon zum alten „Eisen“? Auch im Falle einer breiten Einführung eines Flugzeugrumpfes aus Kohlefaserverstärkten Kunststoffen (CFK) sind die Auftragsbücher mit mehreren Tausend Flugzeugen mit Metallrumpf aus Aluminium (Al) gut gefüllt. Dieser Auftragsbestand wird vorauss...

TiAl-alloys show a low ductility, which limits their application especially in components prone to impact damage like turbine blades or vanes. Therefore, the influence of impact damage on the mechanical behavior of a cast and a forged TiAl-alloy has been investigated. Ballistic tests were performed with impact energies up to several Joules. In ord...

An application field for carbon fibers gaining more and more in importance is composite technology. The combination of reinforcing fibers and a polymer matrix leads to a high-performance material allowing weight reductions of more than 20 % compared to aluminum and more than 50 % compared to steel. Therefore, it is no wonder that all modern aircraf...

The adaption and validation of an elastic-damage material model for aramid paper used in foldcore structures is presented. Aramid paper structures under compression fail in a complex buckling mode combined with face cracking at the buckle peaks. The constitutive modelling was adapted to shell elements in the explicit solver PAMCRASH with considerat...

One of the main problems representing a barrier for TiAl gas turbine applications is its low ductility, especially in reference to impact damage of turbine blades or vanes. For that reason the influence of high-speed impact damage on the mechanical behaviour of a cast TNBV3B TiAl alloy and a forged alloy with a similar composition but improved duc...

The scatter in fatigue life of a forged, fine-grained Ti-6Al-2Sn-4Zr-2Mo-0.1Si (Ti6242) has been studied as a function of the height of the maximum stress level by testing 15 specimens per stress level. As expected the scatter in fatigue life increases at decreasing maximum stress. The smallest scatter in fatigue life is found for 15 specimens test...

Investigations were conducted to get an insight into the crack development during the carbonization of CFRP components and to understand the mechanisms ruling this cracking. It was found that the major crack types are micro-cracks caused by fibre–matrix-debonding, transversal cracks and partial delaminations. Cracking starts with the onset of pyrol...

The development of the crack patterns during the pyrolysis of carbon fibre reinforced plastics (CFRP) to carbon/carbon composites as the second manufacturing step in the liquid silicon infiltration (LSI) process was investigated. In the basic examination reported previously, it was discovered that a substantial amount of cracking occurs beyond 650°...

Due to its outstanding high-temperature properties, TiAl is a promising candidate for applications up to 700 degrees Celsius in the high pressure compressor and the low pressure turbine. One of the main problems which represent a barrier for application in gas turbines is its low ductility, especially in relation with impact behaviour. To clarify t...

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