Ulrich Müller

University of Natural Resources and Life Sciences Vienna | boku · Material Science and Process Engineering, Institute of Wood Technology and Renewable Materials

With growing advocacy for structural wood-based materials in urban construction, the pressure on a sustainable supply of round wood will significantly increase over the next decades. To prevent severe material shortages, the available raw material needs to be processed as efficiently as possible. To do so, in-depth knowledge about the process effic...

Owing to increased environmental demands to replace petroleum-derived materials with more environmentally friendly materials, research has been directed towards the potential of using wood in the automotive industry. This study extensively investigates the compressive strength ( f c ) of two hardwood species (beech and birch) with different anatomi...

Wood, being renewable and highly abundant material, with excellent high specific strength and stiffness, has received increasing attention to be used in high performance applications such as the structural element of a battery case in an electric vehicle. For a successful implementation of wood in the automotive sector, it is, therefore, crucial to...

Natural wood colors occur within a wide range from almost white (e.g., white poplar), various yellowish, reddish, and brownish hues to almost black (e.g., ebony). The intrinsic color of wood is basically defined by its chemical composition. However, other factors such as specific anatomical formations or physical properties further affect the optic...

Following the natural structure of the nacre, the material studied consists of a multitude of hexagonal tiles that are glued together in an offset manner with a ductile adhesive. This so-called "wood nacre" consists of macroscopic tiles of birch wood veneer with a thickness of 0.8 mm and a size of 20 or 10 mm in diameter in order to mimic the arago...

In Austria, paulownia (Paulownia spp.) has not been approved as a forest species. Because of the enormous annual growth and the promising mechanical and physical properties of this tree species, it is grown in short-rotation and value timber plantations in Central Europe. Previous studies have addressed the forestry and silvicultural aspects of dif...

Solid birch wood ( Betula pendula ) was investigated with a newly developed ultrasonic resonance test set-up enabling accelerated fully reversed fatigue experiments of wood. Ultrasonic fatigue lifetimes were measured at a cycling frequency of about 20 kHz up to 10 ⁹ load cycles. For comparison, servo-hydraulic fatigue tests at 50 Hz cycling frequen...

Regarding mechanics, wood is one of the most efficient materials available. Due to its unique combination of composite and cellular microstructure, it exhibits superb specific mechanical properties which exceed many man-made materials. However, concerning absolute mechanical properties, wood is often inferior to metals and novel engineered composit...

Cellulose (rayon) filaments were exposed to various concentrations of hydrochloric acid under aqueous and non-aqueous conditions in order to study differences in degradation. Two sources of polymeric diphenylmethane diisocyanate (pMDI) were used as non-aqueous media. As a consequence of the production process, pMDI was found to contain residual hyd...

Wood as an engineering material shows benefits like high specific strength and stiffness in fibre direction, low cost, and a wide availability. Wood is a semi-brittle material. It shows a low failure strain under tensile loading but a high ductility and energy absorbing capability under compression both in and across the fibre direction. This high...

Fatigue properties of sycamore maple (Acer pseudoplatanus) under cyclic tension, cyclic compression and tension-compression loading at 50 Hz are investigated. Furthermore, for the first time, fatigue test results of wood generated with the ultrasonic fatigue testing technique at 20 kHz under tension-compression loading are presented. Cyclic propert...

In order to use wood for structural and load-bearing purposes in mechanical engineering, basic information on the impact behaviour of the material over a wide temperature range is needed. Diffuse porous hardwoods such as solid birch wood (Betula pendula) and solid beech wood (Fagus sylvatica) are particularly suited for the production of engineered...

Most engineered wood components and their performance are dependent on the use of adhesives. To be able to conduct simulations, a general understanding about their mechanical behaviour under different load cases and environmental conditions is needed. Especially the temperature-dependent elasticity is of great importance for future applications as...

In recent times, a clear trend towards the use of biobased materials can be seen in many areas. Apart from beneficial ecological properties, high strength and stiffness at low weight are desirable in structural applications, a combination typically offered by cellulose-based materials. As an adaption to mechanical stresses acting on the living orga...

The present study investigated the effect of selected structural parameters on the mechanical performance of regenerated cellulose composites. The experimental setup comprised continuous viscose (rayon) yarns embedded in a matrix of epoxy resin. Mechanical and microscopic characterizations involved comparing the following: yarns consisting of untwi...

With 888 million tons of CO2 emitted, road transport is responsible for 26% of total greenhouse gas emissions in the EU (Destatis 2020). As vehicle weight accounts for around a quarter of total fuel consumption, it significantly drives CO2 emissions (Kirschbichler et al. 2016). At the same time, more stringent requirements in terms of vehicle safet...

Birch (Betula pendula Roth.) and beech (Fagus sylvatica L.) solid wood and plywood were overmolded with polyamide 6 (PA 6) and polypropylene (PP) to investigate their mechanical properties and interfacial adhesion. In the case of PA 6, maximum tensile shear strengths values of more than 8 to 9 MPa were obtained for birch and beech, respectively. Th...

Obwohl die Wissenschaft nicht den Anspruch hat, ethische Fragen zu beantworten, hat sie doch gewisse ethische Verpflichtungen, die besonders seit Beginn der Pandemie sträflich vernachlässigt wurden.

In the development of structural composites based on regenerated cellulose filaments, the physical and chemical interactions at the fibre-matrix interphase need to be fully understood. In the present study, continuous yarns and filaments of viscose (rayon) were treated with either polymeric diphenylmethane diisocyanate (pMDI) or a pMDI-based harden...

DEUTSCH: Die Implementierung von Holz als strukturelles Leichtbaumaterial in neuen Hochleistungs-Anwendungen erfordert eine Stück-für-Stück-Charakterisierung der Rohmaterialien. Vor allem Furniere finden aufgrund der hervorragenden Eigenschaften sowie der guten Verarbeitbarkeit große Beachtung. Zu diesem Zwecke wurde die zerstörungsfreie Prüfung v...

The use of wood in high-performance composites based on laminated veneer products, plywood or wood hybrid elements thereof requires accurate prediction of strength of each individual ply. Previous research has shown that one dominating factor influencing the strength of birch veneers is the fibre orientation. The present study investigates the vali...

The development of high-performance, veneer-based wood composites is a topic of increasing importance due to the high design flexibility and the comparable mechanical performance to solid wood. Part of this improved mechanical performance can be contributed to the size effect present in wood. Based on previous findings in the literature, this size...

Die aktuelle Debatte zur Verbesserung der CO -Bilanz von zukünftigen Fahrzeugkonzepten dreht sich auch um Gewichtsreduktion und Verwendung nachhaltiger Materialien. Die Entwicklung von Holz-Hybrid-Komponenten verlangt nach neuen Produktionstechnologien, Materialsimulation, Fertigungsverfahren und Beherrschung von natürlichen Werkstoffen - die wesen...

Building in timber is increasing in importance and becoming a huge trend supported by European governments to contribute to the aim of a drastic CO2 reduction in the atmosphere by storage and substitution. The building sector is the major consumer for solid wood, so far dominated by softwood species. Inherent log wood raw material characteristics a...

The project WoodC.A.R. investigates the capabilities of wood and engineered wood-products (EWPs) for their application as a load-bearing material in automotive applications. For crash-relevant components, materials have to provide a high impact bending energy over a wide range of climatic conditions. This study investigates the effect of temperatur...

Robotik, Internet der Dinge, künstliche Intelligenz und Industrie 4.0 - die Digitalisierung schreitet mit zunehmender Geschwindigkeit voran. Als nächstes steht uns bereits Industrie 5.0 ins Haus. Die Möglichkeiten, die sich daraus für die Holzbranche ergeben, sind enorm. Anhand des Projekts WoodC.A.R. und geplanter Forschungsaktivitäten zeigen wir,...

Robotics, the Internet of Things, artificial intelligence and Industry 4.0 - digitalisation is advancing at an ever faster rate. In a next step, Industry 5.0 is already waiting for us. But this also offers enormous opportunities for the forest-wood chain. With the WoodC.A.R. project and future research activities we will show what digitisation mean...

The crossed lamellar structure (CLS) found in mollusc shells is an excellent example for nature’s ability to form complex hierarchical microstructures with a remarkable balance between strength and toughness. The CLS has become the subject of numerous studies focusing on the replication of theunique microstructure using synthetic composites. The pr...

The use of wood-based materials in the automotive industry is currently under discussion and investigation. One of the major material requirements for such applications is sufficient weathering stability. This can be demonstrated by an accelerated aging process in which the samples are exposed to changing climatic conditions and a spray mist of an...

A novel wood composite based on specially produced wooden particles, the so-called macro-fibres, is presented. Forest thinnings were used as raw material for the production of macro-fibres. The disintegration process was a combined-squeezing-cutting process, which takes into account the naturally grown fibre orientation of the wood. The resulting m...

Wood and natural fibers exhibit an advantageous combination of good mechanics at comparably low density. Nevertheless, comparing absolute strength and stiffness, wood is clearly inferior to materials such as metals and engineered composites. Since there is a strong correlation between wood density and wood mechanical performance, densification by t...

In various engineering applications, screws are commonly used to connect wood and engineered wood products to each other. To describe the axial loads which may be transmitted with these components, it is important to quantify the resulting clamping forces in relation to the applied screw torques. In this initial study, birch plywood panels with thi...

Wood is a highly optimised lightweight material showing excellent mechanical properties in the fibre direction. However, strength and stiffness are low perpendicular to grain. Due to knots, stem taper and spiral grain, the wood material includes local and global fibre deviations. Mechanical disintegration of logs into veneers and sawn timber is mor...

In various engineering applications, self-tapping screws are used to connect timber members. To describe their load-deformation relationship, a better understanding of the strain along the mechanical interface (i.e., timber-screw interface) is required. With a focus on the axial loading of self-tapping screws, only a few studies have dealt with the...

The currently pursued implementation of wood into novel high performance applications such as automotive parts require knowledge about the material behaviour including ultimate strength. Previous research has shown that fiber deviation seems to be the dominating factor influencing the strength of thin veneers. This study aims to further investigate...

Die Erfindung betrifft ein Aufprallelement (2), insbesondere ein Seitenaufprallschutzelement für eine Fahrzeugseitenstruktur, umfassend eine nichtmetallische Drucklage (6) und eine nichtmetallische Zuglage (7), die derart miteinander verbunden sind, dass zwischen ihnen ein Zwischenraum (8) ausgebildet ist, wobei im Zwischenraum (8) ein Füllmaterial...

In technical applications of wood-based composites, the predictability of elasticity and strength is important. The aim of this study was to predict the static modulus of elasticity and tensile strength of thin (0.55 mm ± 0.05 mm) birch veneers. Based on the dynamic modulus of elasticity estimated via means of wave transmission time the observed dy...

Golf tees with a plastic head and wooden shaft were prepared by back injection moulding of a beech wood (Fagus sylvatica) shaft with different polymers (i.e. ionomer, polypropylene, and polyamide). In order to facilitate adhesion between the polymer melt and the wood surface, the wooden shafts were pre-treated with different primer substances, incl...

1 Introduction and Motivation The project ‘WoodC.A.R.’ (Computer Aided Research) is aiming for the introduction of wood and wood-based materials as a structural and load-bearing material in mechanical engineering. In the last three decades, wood has gained momentum as a building material in civil engineering thanks to developments and advancements...

In state-of-the-art wood science, computerized engineering methods like finite-element modelling (FEM)are commonly used to engineer and optimize high quality products and structures. Some of these mainly wood-based structures are analysed, improved and evaluated within the research project WoodC.A.R.(Wood – Computer Aided Research) by applying FEM....

Multi material mix is a promising approach to reduce weight and the carbon footprint in automotive engineering at competitive costs. As a result, automotive industry is getting more venturous, exploring and applying other materials than metals and plastics-e.g. fibre reinforced plastics (FRPs). In this context, engineered wood products (EWPs) and w...

Wood can be considered as a composite material at multiple length scales: - solidwood is a laminate of annual rings, - annual rings are a laminate of spring and autumn wood cells, - wood cells are a structural composites – similar to honeycombs, - cell walls are laminates of fibre-reinforced wall-layers. In terms of mechanical behavior in longi...

Neue Klimamodelle bestätigen bisherige Prognosen. Mit einem Temperaturanstieg von 3°C in den nächsten 80 Jahren ist zu rechnen. Damit ist besonders die Forstwirtschaft, die über Generationen hinweg vorausdenken muss, mit besonderen Herausforderungen konfrontiert. Dazu kommen Probleme, die es im Zusammenhang mit zunehmenden Schadholzaufkommen zu bew...

Sustainability plays an increasingly important role in the automotive industry. In order to reduce the ecological footprint, the suitability of alternative bio-based materials like wood is investigated within the project WoodC.A.R. In order for wood to be used as an engineering material for structural components or even crash relevant structures, i...

Die Erfindung betrifft ein Aufprallelement (2), insbesondere ein Seitenaufprallschutzelement für eine Fahrzeugseitenstruktur, umfassend eine nichtmetallische Drucklage (6) und eine nichtmetallische Zuglage (7), die derart miteinander verbunden sind, dass zwischen ihnen ein Zwischenraum (8) ausgebildet ist, wobei im Zwischenraum (8) ein Füllmaterial...

Wood provides high stiffness, strength, excellent damping, high resistance against fatigue and a very low density paired with low material costs. Properly applied, modern wood composites are competitive to metals and fibre-reinforced polymers. However, the application of wood and wood composites in automotive engineering requires precise and reliab...

Presentation of the use cases, design studies, methods applied and tests performed within the research program WoodC.A.R.

Autobauer CHARLES MORGAN konstruiert nicht nur hochwertige Autos, sondern „fährt auch auf Holz ab“ und steht seit Beginn mit dem Forschungsteam WoodC.,A.R. im fachlichen Austausch. Impulsvortrag über die Projektinhalte und erste Projektergebnisse von WoodC.A.R. von Dr. Ulrich Müller https://www.forstholzpapier.at/index.php/35-aktuelles/238-oester...

Wer bin ich und woher komme ich? Diesen Fragen muss sich der Waisenjunge Juma aus Afrika als Erwachsener stellen. Höhen, Absurditäten und Niederlagen zeichnen den Weg dieses zutiefst menschlichen Schicksals, auf dem ein Antiheld die Chance auf Größe hat. Juma wächst bei seinen Zieheltern, der erfolgreichen Rechtsanwältin Sarah Nicolini und dem po...

Wood and wood-based components provide excellent mechanical properties (i.e. high stiffness, strength, high resistance against fatigue, low density) paired with low raw material costs. In different applications (e.g. vehicles) it is necessary to join wood-based components and non-wood materials using bolts or screws in order to meet required stiffn...

In contemporary wood science, computer-aided engineering (CAE) systems are commonly used for designing and engineering of high-value products. In diverse CAE systems, high-fidelity models with a full material description, including elastic constants such as Poisson’s ratios, are needed. Only few studies have dealt so far with the investigation of t...

In summary, it can be said that with the derived model approach, functional structural components consisting of wood composite materials can already be qualitatively designed and evaluated in an early vehicle development phase regarding basic function up to the initial failure. Furthermore, a vast amount of open research questions in the area of nu...

In summary, it can be said that with the derived model approach, functional structural components consisting of wood composite materials can already be qualitatively designed and evaluated in an early vehicle development phase regarding basic function up to the initial failure. Furthermore, a vast amount of open research questions in the area of nu...

Fuel reduction and CO2-balance is heavily discussed in automotive engineering. improvements of the ecologic footprint require innovative vehicle concepts and involvement of bio-based materials. Novel materials, material combinations and composites are urgently needed. Wood provides high stiffness, strength, excellent damping, high resistance agains...

A multi-material mix is a promising approach to saving weight and improving the CO2 balance in automotive engineering at competitive costs. As a result, automotive industry is getting more venturous, exploring and applying other materials than metals and plastics – e.g. fibre-reinforced plastics (FRPs). In this context engineered wood products (EWP...

It seems to be a simple part, but the whole Ardenner cassis construction is based on a complex computer aided engineering process.

Fuel reduction and CO2-balance is heavily discussed in automotive engineering. Improvements of the ecologic footprint require innovative vehicle concepts and involvement of bio-based materials. Novel materials, material combinations and composites are urgently needed. Wood provides high stiffness, strength, excellent damping, high resistance agains...

Key message The main achievement of this study is an extension of the existing model of Shigo of the branch-stem junction of coniferous trees by introducing the concept of a sacrificial tissue. This tissue is acting as a predetermined breaking point between branch and stem and limits fracture and damage to a small and isolated zone within the tree....

The adhered wood in multi-layered panels is subjected to different stress and strain states as a result of moisture induced swelling and shrinking. Consequently, it is expected that the adhesive layer has to compensate these stresses and responds beside elastic with viscoelastic deformation. To better understand the humidity dependent mechanical b...

Nachhaltigkeit, Materialverfügbarkeit, Multimaterialmix und Leichtbau sind zentrale Trends des zukünftigen Fahrzeugbaus. Nach neuen Materialien und Materialkombinationen wird intensiv gesucht. Holz besitzt hervorragende Werkstoffeigenschaften bei niedriger Dichte. Richtig eingesetzt sind Holzwerkstoffe kompetitiv zu faserverstärkten Kunststoffen un...

ppt presentation

Microfibrillated cellulose (MFC) is a fascinating material with an obvious potential for composite reinforcement due to its excellent mechanics together with high specific surface area. However, in order to use this potential, commercially viable solutions to important technological challenges have to be found. Notably, the distinct hydrophilicity...

The deformation of wood due to swelling and shrinkage induced by water absorption and desorption of cell wall components is still challenging the engineering of dimensionally stable multi-layer wood-based panels. To overcome this problem and to accelerate the developing process of new wood-based panels, numerical methods developed to describe the d...