Mechanical Characterisation of Densified Hardwood with Regard to Structural Applications

The demand for high-performance,yet eco-friendly materials is increasing on all scales from small applications in the car industry,instrument or furniture manufacturing to greater dimensions like floorings,balcony furnishings and even construction.Wood offers a good choice on all of these scales and can be modified and improved in many different ways.In this study,two common European hardwood species,Beech(Fagus sylvatica L.)and Ash(Fraxinus excelsior L.)were densified in radial direction by thermo-mechanical treatment and the densified product was investigated in an extensive characterisation series to determine all relevant mechanical properties.Compression in the three main directions(longitudinal,tangential,radial)and tension perpendicular to the grain(tangential,radial)were tested and compared to reference specimens with native density.Strength and modulus of elasticity were determined in all tests.In addition,a Life Cycle Assessment was carried out to evaluate the environmental impact associated to the densification process.The experimental investigations showed that strength and stiffness of hardwood in the longitudinal and tangential directions improve significantly by radial densification,whereas some properties in the radial direction decrease.The Life Cycle Assessment showed that artificial wood drying has higher impact than wood densification.Furthermore,the transport distance of the raw material highly influences the environmental impact of the final densified product.The paper then also offers an overview of possible applications in structural timber construction.Densified hardwood is a viable option as local reinforcement,where high compressive or tensile strength is needed.The wood densification process offers an alternative to the use of carbon-intense steel components or hardwoods from tropical forests.

Characterising Mechanical Properties of Flowing Microcapsules Using a Deep Convolutional Neural Network

Deformable microcapsules are widely used in industries and also serve as a mechanical model of living biological cells.In this study,we develop a novel method,by integrating a deep convolutional neural network(DCNN)with high-fidelity mechanistic capsule modelling,to identify the membrane constitutive law and estimate associated parameters of a microcapsule from its steady deformed profile in a capillary tube.Compared with conventional inverse methods,the present approach is more accurate and can increase the prediction throughput rate by a few orders of magnitude.It can process capsules with large deformation in inertial flows.Furthermore,the method can predict the capsule membrane shear elasticity,area dilatation modulus and initial inflation from a single steady capsule profile.We explore the mechanism that the DCNN makes decisions by considering its feature maps,and discuss their potential implication on the development of inverse methods.The present method provides a promising tool which may enable high-throughput mechanical characterisation of microcapsules and biological cells in microfluidic flows.

Relationship between Atmospheric Dew Point and Sinterability of Al-Si Based Alloy

Al-Si based alloys are interestingly used to produce automotive components. Fabrication of such components by powder metallurgy （PM） has been developed continuously. During PM, several parameters affect the sinterability of the aluminium powder, including atmospheric dew point which is regarded as one of the crucial parameters. The objective of this work was to investigate the effect of the atmospheric dew point on the sinterability of AI-14.9Si-2.4Cu-0.55Mg by studying the sintering characters obtained under various atmospheric dew points. The aluminium alloy powder was pressed into tensile specimens and subsequently sintered in a nitrogen atmosphere at 560 ℃ for 60 min with varied atmospheric dew points. The results show that as the dew point decreased, the sintered properties were improved. The atmospheric dew point of -38.4 ℃ is sufficient to obtain good sintering characters and it is achievable in a commercial furnace.