Electrooptic properties of mixtures of 4-cyano-40 -pentylbiphenyl (5CB) thermotropic liquid crystal with four different inorganic dopants: (i) MoSI nanowires, (ii) MnO 2 nanorods, (iii) Ag nanowires, and (iv) WS 2 nanotubes were investigated by a conventional optical measurement technique. The dopant concentrations were in the range from 0.1 to 0.5 wt%. In all mixtures aggregation of the 1D nanoparticle (1D-NP) material was observed, therefore electrooptic response was probed in the regions in-between the aggregates. All four 1D-NP dopants produce a decrease of the threshold voltage for electrooptic switching and also a decrease of the corresponding switching times. The most profound effects are observed for MnO 2 /5CB system, which exhibits a reduction of the threshold voltage by a factor of 1.7 and a reduction of the total switching time by a factor of 1.5. The effect is associated with an increase of the dielectric anisotropy of the mixture. The specific behaviour of the MnO 2 nanorods is attributed to their relatively low aspect ratio that provides most suitable conditions for good alignment in the liquid crystal host. , are naturally suited for hosting 1D nanoparticles (1D-NPs), such as nanowires, nanotubes and nanorods. This is, because dispersions of rod-shaped objects in isotropic fluids commonly exhibit spontaneous formation of orienationally ordered phases by themselves [2-5], therefore introducing them into an LC host is expected to result in a synergetic orientational ordering process. However, in reality, the mixing behaviour is quite complex and addition of a relatively small amount ( 1 wt%) of 1D-NPs to the nematic LC host can cause both: increase or decrease of the orientational order of the host medium [6,7]. The effect depends on the size of the dispersed 1D-NPs with respect to the size of the LC molecules, on the interaction between the NPs and on the interfacial interaction between the NPs and the LC

The objective of this paper is the computational and experimental study of the fracture behavior of spruce wood under quasi-static loading conditions during a three-point bending test. The experimental tests were performed on the electronic testing machine Zwick Z100 (Zwick-Roell GmbH & Co. KG, Ulm, Germany) with displacement control, according to the standard International Standard Organisation (ISO) 13061-4: 2014. The specimens were made of Norway spruce (Picea abies) wood, with dimensions of 25 mm × 25 mm in cross-section and 549 mm in length. Six tests were performed for each orientation (radial and tangential) of the wood fibres. Based on the experimental results, the computational model was created and validated by considering the mechanical responses in two different directions due to the orientation of the wood fibres. An orthotropic material model with damage evolution was selected as the computational model. The computational model was validated using the inverse procedure for the determination of the constitutive material parameters, including the damage parameters of three-point bending test specimens. A finite element method (FEM) in the framework of program package ABAQUS was used for the computational simulation, while the open code Optimax was used for the optimization procedure. Comparison between the experimental and computational force vs. the displacement response showed a very good correlation in the results for the spruce wood specimens under three-point bending tests, with Pearson′s correlation coefficient of r = 0.994 for the tangential and r = 0.988 for the radial orientation. Therefore, validation of the proposed computational model was confirmed, and can be used further in numerical simulations of the fatigue behavior of wood specimens.

In product design, the focus is increasingly shifting towards optimizing and increasing the efficiency of the development process. This can be achieved with advanced numerical tools, but these methods require precise knowledge of material properties. One of the desired properties is the dynamic load behavior of the material. The research is directly related with the company that developed the slender wooden beams used in industry to produce windows of larger dimensions (height over 3 m). For the testing of wooden beams, the pneumatic four-point bending fatigue test rig was developed. In this paper, the whole structure of the test rig is described in detail. Based on the performed experiments of dynamic strength, the Woehler curve was determined, which serves as a necessary input for further numerical simulation of the fatigue process of wood-based beams. Knowledge of the response of wood to dynamic loads is very important to predict its life expectancy in various products.