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Foam-forming has in the past predominantly been used to create two-dimensional sheet-like fibrous materials. Allowing the foam to drain freely and decay under gravity, rather than applying a vacuum to remove it rapidly, we can produce lightweight three-dimensional fibrous structures from cellulose fibres, of potential use for thermal and acoustic insulation. μ CT scanning of the fibrous materials enable us to determine both void size distributions and also distributions of fibre orientations. Through image analysis and uniaxial compression testing, we find that the orientation of the fibres, rather than the size of the voids, determine the compressive strength of the material. The fibrous samples display a layering of the fibres perpendicular to the direction of drainage of the precursor liquid foam. This leads to an anisotropy of the compressive behaviour of the samples. Varying the initial liquid fraction of the foam allows for tuning of the compressive strength. We show an increase in over seven times can be achieved for samples of the same density (13 kg.m -3 ). Graphic abstract

This new book-the first of its kind-examines the use of algorithmic techniques to compress random and non-random sequential strings found in chains of polymers. The book is an introduction to algorithmic complexity. Examples taken from current research in the polymer sciences are used for compression of like-natured properties as found on a chain of polymers. Both theory and applied aspects of algorithmic compression are reviewed. A description of the types of polymers and their uses is followed by a chapter on various types of compression systems that can be used to compress polymer chains into manageable units. The work is intended for graduate and postgraduate university students in the physical sciences and engineering.

The paper presents an experimental program aiming at assessing the mechanical performance of rammed earth walls, namely under compression and shear loading. Axial compression and diagonal compression tests were carried out for this purpose, which allowed determining important mechanical parameters, such as compressive strength, Young’s modulus, Poisson’s ratio, shear strength and shear modulus. Furthermore, it allowed assessing the level of non-linear behaviour of the respective stress–strain relationships as well as the failure modes. The experimental results were then used in the calibration of numerical models (finite element method) for simulating the non-linear behaviour of rammed earth under shear loading. Both macro- and micro modelling approaches were considered for this purpose. The total strain rotating crack model was used to simulate the behaviour of the rammed earth material, while the Mohr–Coulomb failure criterion was used to simulate the behaviour of interfaces between layers. In general, the numerical models achieved good agreement with the experimental results, but uncertainties related to the definition of the input parameters required to perform a sensitivity analysis. The compressive strength, the Poisson’s ratio, the tensile strength and the tensile fracture energy revealed to be the most important parameters in the analyses.

This study aimed to compare the biomechanical efficacy of rim plating versus conventional posterior buttress plating for fixing posterolateral tibial plateau fractures (PLTPFs). Sixty synthetic tibial models were divided into three groups: posterior buttress plating with a 3.5-mm locking compression T-plate, rim plating with a 2.7-mm variable-angle cloverleaf plate and two anteroposterior screws, and rim plating alone. Static compression and cyclic loading tests were conducted to assess mechanical stability under simulated physiological conditions. Failure loads averaged 2235.75 N, 2017.46 N, and 1743.95 N for the three groups, respectively, all exceeding the 1500-N threshold corresponding to approximately 250% of body weight. Cyclic loading exerted minimal displacement across groups, with no significant differences in stability. Rim plating demonstrated slightly lower failure loads than traditional posterior buttress plating but provided sufficient biomechanical support for PLTPFs. Its performance under static and cyclic loading indicates its feasibility as an alternative that offers adequate stability while potentially reducing surgical invasiveness. These results suggest that rim plating is a biomechanically viable alternative for the management of PLTPFs, offering adequate stabilization with the potential advantage of reduced surgical invasiveness.

The preparation of siloxane‐containing emulsion‐templated porous polymers via thiol‐ene chemistry is explored. Emulsion templating, a technique that utilizes a liquid‐liquid system separated into two or more phases, was exploited to produce monolithic materials with controlled morphologies from 1,3‐divinyltetramethyldisiloxane (DVTMDS) and trimethylolpropane tris(3‐mercaptopropionate) (TMTMP). Emulsions were prepared using varying ratios of dichloroethane and chloroform, then cured photochemically to deliver flexible emulsion‐templated porous polymers. The differences in polarity and density influenced emulsion stability and, in turn, the void and pore sizes (and the respective distributions) of the resulting materials as ascertained by SEM analysis. The mechanical properties of the resulting materials were tested under cyclic compression for up to 100 cycles and limited changes in hysteresis were observed. Using a ratio of 25:75 DCE:CHCl3 appears optimal in the preparation of DVTMDS/TMPTMP based emulsion‐templated porous polymers; samples prepared using this ratio had the largest mean interconnecting pore sizes by SEM, and showed both the least damage and most consistent hysteresis from compression testing. This sample was taken further to 5000 compression cycles, after which exceptional mechanical performance was maintained demonstrating the outstanding properties of these porous siloxane‐containing materials. We show that by tailoring the mixed solvent content, our photocured emulsion‐templated porous siloxane‐based copolymers can undergo high hysteresis over 5000 compressive cycles with minimal damage. These thiol‐ene siloxane polymers show exceptional mechanical performance, which was maintained, demonstrating these outstanding properties. Samples prepared under optimal conditions had the largest mean interconnecting pore sizes, as determined by SEM.

A Scotch pine wood annual ring (AR) structure was modeled using AutoCAD and SolidWorks software. The same AR was separately modeled to create earlywood (EW), transition wood (TW), and latewood (LW). All 3D models were additively manufactured using Hyper PLA material and Creality 3D printer. Compression tests were performed to obtain load-deformation curves. The maximum force, compression strength (CS), and deformation at 500N load were determined. The EW presented the highest deformation while LW presented the highest CS. The TW and AR displayed intermediate behaviors. Finite Element Modeling and Analysis (FEM&A) was performed to compare with the experimental results. The numerical results presented considerable high deviations from the experiment. Around 78.7%, 41.7%, 89.3%, and 52% differences were observed for AR, EW, TW, and LW, respectively. Therefore, the capability of the model for prediction of mechanical behavior was not found to be successful. The essential reason for these discrepancies is the contrast between the orthotropic nature of wood and partially anisotropic nature of 3D printed models even if the filament is isotropic material. However, it should be taken into consideration that such high differences are not abnormal for the wood material even if the tested samples belong to the same log because of the variations in the material due to sampling details such as cutting location, orientation, etc. Furthermore, when considering the 3D printing parameters such as infill density, printing orientation, layer height, etc., the FEM&A results can be considered partially successful, although the differences were high.

Mechanical properties of wood-inspired cell wall geometries were considered through compression testing and Finite Element Analysis (FEA) with ANSYS simulation. Six models, including earlywood, latewood, and various array configurations, were fabricated via 3D printing using acrylonitrile butadiene styrene (ABS) filament. Compression tests highlighted the annual ring model’s robustness, exhibiting a maximum load of 12707 MPa, while the 4×3 matrix displayed the lowest strength at 4247 MPa. Shifting rows led to reduced strength, which was particularly evident in vertical prints. An analysis of variance revealed significant differences in mechanical properties. Discrepancies between experimental tests and FEA results ranged from -45.9% to 35.2%. Earlywood exhibited a maximum deformation of 2.6 mm, whereas latewood showed lower deformation, indicating geometry’s influence on material behavior. Mesh quality remained consistent, ensuring dependable simulation outcomes. These findings underscore the pivotal role of geometry in compression resistance, laying the groundwork for future studies on wood densification mechanisms and the development of customized wood composites.

Plantar pressure abnormalities have a significant impact on mobility and quality of life. Real-time pressure monitoring is essential in clinical and rehabilitation settings for assessing patient progress and refining treatment protocols. Instrumental and particularly smart insoles offer a promising solution by collecting biomechanical data during daily activities. However, determining the optimal combination of sensor type, number, and placement remains a key challenge for ensuring accurate and reliable measurements. This study proposes a methodology for identifying the most appropriate sensor technology for wearable insoles, with a focus on data accuracy, system efficiency, and practical applicability. Additionally, it examines the correlation between sensor signals and material behavior during compression testing. Two insole prototypes underwent compression testing: one equipped with a Force Sensitive Resistor (FSR) sensor and one with a piezoelectric sensor, both positioned at the heel. Three trials per prototype assessed consistency and repeatability. Real-time data acquisition utilized a microcontroller system, and signals were processed using a sixth-order Butterworth low-pass filter with a 5 Hz cutoff frequency to reduce noise. FSR sensors demonstrated stable static responses but saturated rapidly beyond 20 N, with performance degradation observed after repeated loading cycles. Piezoelectric sensors exhibited excellent dynamic sensitivity with sharp voltage peaks but proved unable to measure sustained static pressure. FSR sensors are well-suited for static postural assessment and continuous pressure monitoring, while piezoelectric sensors excel in dynamic gait analysis. This comparative framework establishes a foundation for developing future smart insole systems that deliver accurate, real-time rehabilitation monitoring.

This study introduces and validates a miniaturized testing methodology for the complete orthotropic characterization of structural plywood, including out-of-plane directions that are typically difficult to access. Novel small-scale geometries were developed for tension and shear configurations, with compliance corrections applied to ensure accurate stress–strain responses. The method proved reliable and sensitive to mechanical differences arising from veneer architecture, adhesive type, and interfacial bonding. Two sets of 18 mm structural plywood panels—manufactured with distinct adhesive systems, one bio-based (F1) and one phenol-formaldehyde (F2)—were systematically tested under tensile, compressive, and shear loading in ten orthogonal configurations (Tx, Ty, Tz, Cx, Cy, Cz, τxy, τyx, τxz, τyz), following standards NCh 3617, EN 789, and ASTM B831. Tensile moduli were approximately twice the corresponding compressive values, while out-of-plane moduli reached only 6–11% of in-plane values. F1 exhibited higher stiffness in both tension and compression, particularly in transverse directions, due to thicker perpendicular veneers enhancing bending restraint and shear coupling. In contrast, F2 achieved greater peak shear strength owing to its more uniform veneer structure, which improved stress distribution and delayed interlaminar failure. Observed asymmetry between tension and compression reflected microstructural mechanisms such as fiber alignment and cell-wall buckling. The miniature-specimen data provide reliable input for constitutive calibration and finite-element modeling, while revealing clear links between veneer-thickness distribution, shear-transfer efficiency, and macroscopic performance. The proposed framework enables efficient, reproducible orthotropic characterization for optimized, lightweight, and carbon-efficient timber systems.

This study proposes a new, doubly re-entrant auxetic unit-cell design that is based on the widely used auxetic honeycomb structure. Our objective was to develop a structure that preserves and enhances the advantages of the auxetic honeycomb while eliminating all negative aspects. The doubly re-entrant geometry design aims to enhance the mechanical properties, while eliminating the buckling deformation characteristic of the re-entrant deformation mechanism. The effects of the geometric modification are described and evaluated using two parameters, offset and deg. A series of experiments were conducted on a wide range of parameters based on these two parameters. Specimens were printed via the vat photopolymerization process and were subjected to a compression test. Our aim was to investigate the mechanical properties (energy absorption and compressive force) and the deformation behaviour of these specimens in relation to the relevant parameters. The novel geometry achieved the intended properties, outperforming the original auxetic honeycomb structure. Increasing the offset and deg parameters results in increasing the energy absorption capability (up to 767%) and the maximum compressive force (up to 17 times). The right parameter choice eliminates buckling and results in continuous auxetic behaviour. Finally, the parameter dependency of the deformation behaviour was predicted by analytical approximation as well.