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Porous building materials, such as board materials, wood, stones, fired clay materials, and bio-based materials, often have anisotropic properties. This study investigates adequate numerical models for the coupled hygrothermal and mechanical behaviors of strongly anisotropic building materials during freezing and thawing. First, strain measurements are reported for two types of fired clay materials to confirm the anisotropy of deformation during freezing and thawing. In calculations, the anisotropy of the Biot coefficient of a material is considered based on anisotropic poroelasticity. The comparison between the measurements and calculations revealed that the anisotropic deformation during the measurement cannot be reproduced without considering the anisotropies of the Biot coefficient as well as those of the mechanical properties. In addition, analysis of the causes of the deformation reveals that the expansion in the direction normal to the material thickness due to the water pressure development during the freezing is suppressed by the small Biot coefficient. These results indicate that the anisotropy of the Biot coefficient significantly influence the deformation due to frost actions; consequently, the anisotropic Biot coefficient should be adequately considered in numerical simulations. [ABSTRACT FROM AUTHOR]

[Display omitted] • We reveal the structure of meat analogues with scattering, microscopy, and mechanical techniques. • Anisotropic nanostructural variations are caused by viscosity, temperature, and stresses. • Soy protein concentrate is pre-denatured and maintains this conformation after extrusion. The rising demand for plant-based meat analogues as alternatives to animal products has sparked interest in understanding the complex interplay between their structural and mechanical properties. The ability to manipulate the processing parameters and protein blend composition offers fundamental insights into the texturization process and holds economic and sustainable implications for the food industry. Consequently, the correlation between mechanical and structural properties in meat analogues is crucial for achieving consumer satisfaction and successful market penetration, providing comprehensive insights into the textural properties of meat analogues and their potential to mimic traditional animal produce. Our study delves into the relationship between structural and mechanical anisotropy in meat analogues produced using high moisture extrusion cooking, which involves blending protein, water, and other ingredients, followed by a controlled heating and cooling process to achieve a fibrous texture akin to traditional meat. By employing techniques such as scanning small-angle X-ray scattering, scanning electron microscopy, and mechanical testing we investigate the fibrous structure and its impact on the final texture of meat analogues. We show that textural and structural anisotropy is reflected on the mechanical properties measured using tensile and dynamic mechanical techniques. It is demonstrated that the calculated anisotropy indexes, a measure for the degree of textural and structural anisotropy, increase with increasing protein content. Our findings have significant implications for the understanding and development of plant-based meat analogues with structures that can be tuned to closely resemble the animal meat textures of choice, thereby enabling consumers to transition to more sustainable dietary choices while preserving familiar eating habits. [ABSTRACT FROM AUTHOR]

The effect of ageing and anisotropy in 3D-printed composites including short carbon fibres embedded in a polyamide (PA/nylon®) matrix is analysed experimentally. A testing campaign including tensile and fracture toughness coupons with 100% infill is studied. The effect of anisotropy induced by the Fused Deposition Modelling (FDM) procedure, caused by the alignment of the fibres with the deposition direction (raster angle), is presented. Specifically, results showed that the Young modulus and the elastic limit values are lower for the ＋45/−45 infill configuration with respect to the 0/90 infill configuration. Conversely, the ultimate tensile strength, the ultimate tensile strain, and the fracture toughness values are higher for the ＋45/−45 infill configuration. Moreover, the crack path obtained in fracture toughness coupons always followed the raster angle. Additionally, experimental results show that the 3D-printed composite parts keep the hygrothermal properties associated to the matrix, thus an ageing effect is observed even for standard environmental conditions (room temperature, 50% relative humidity). Specifically, Young modulus, elastic limit and ultimate tensile strength values are lower for the older coupons. The ultimate tensile strain is higher for the older coupons while the fracture toughness is similar. Coupons stored in a desiccator also varied the properties but in a slightly manner. [ABSTRACT FROM AUTHOR]

Presents information on a study which described a solution to the hygrothermoelastic problem associated with an interface discontinuity between dissimilar anisotropic media. Methods; Results; Discussion.

Optimization with Unified Particle Swarm Optimization (UPSO) method is performed for the enhancement of buckling load capacity of composite plates having damage under hygrothermal environment which has received little or no attention in the literature. Numerical results are presented for effect of damage in buckling behavior of laminated composite plates using an anisotropic damage model. Optimized critical buckling temperature of laminated plates with internal flaw is computed with the fiber orientation as the design variable by employing a UPSO algorithm and results are compared with undamaged case for various aspect ratios, ply orientations, and boundary conditions. FEM formulation and programming in the MATLAB environment have been performed. The results of this work will assist designers to address some key issues concerning composite structures. It is observed that the degradation of buckling strength of a structural element in hygrothermal environment as a result of internal flaws can be avoided to a large extent if we use these optimized ply orientations at design phase of the composite structure. This specific application proves the contribution of present work to be of realistic nature. [ABSTRACT FROM AUTHOR]

Sensor components may markedly differ from typical silicon chips. Consequently, versatile attachment methods are required for their interconnections. Anisotropic conductive adhesives (ACA) are interesting materials for attachments of sensors due to their versatility. In this study reliability of ACA attached humidity sensors was studied in hygrothermal conditions. The reliability of the interconnections was found to be excellent even under prolonged exposure showing that high reliability can be achieved with ACA materials in sensor applications. [ABSTRACT FROM AUTHOR]

In this work, the combined effect of moisture and temperature on the bending behavior of simply supported anisotropic cylindrical shells has been investigated. Initially three dimensional equilibrium equations of thermoelasticity, simplified to the case of a generalized plane strain deformations in the axial direction are solved analytically for an anisotropic cylindrical shell strip under thermal loading. Based on the realistic variation of displacements from the elasticity approach, a new 13 term higher order shear deformation theory HSDT13 was proposed for the analysis of an anisotropic cylindrical shell strip under hygrothermal and mechanical loading. The zigzag form of the displacement is incorporated via the Murakami zigzag function. Results are presented for mechanical and thermal loading for various layups and they are validated against the derived elasticity solution. The significance of retaining various higher-order terms in the present model HSDT13, in evaluating the stresses and deflection for composite laminates is brought out clearly through parametric study. Useful results for combined hygrothermal loading are presented in tabular and graphical form. It is expected that the numerical results presented herein will serve as benchmark in future. [ABSTRACT FROM AUTHOR]

Highlights: [•] Unfired clay bricks were made by an extrusion process. [•] The hygrothermal properties differed according to the side considered. [•] The extrusion process influences clay platelet orientation and hygrothermal properties. [Copyright &y& Elsevier]

Nation is the most commonly used membrane material in proton exchange membrane fuel cells. New and used membrane electrode assemblies (MEAs) are subjected to dynamic mechanical analysis (DMA) tests in temperature scan mode to determine the effect of catalyst coating and hygro-thermal aging. DMA tests are also performed using specimens obtained from the rolling and transverse directions to investigate the anisotropic effects of the membrane and the coating. The catalyst coating increases the stiffness and brittleness of the membrane. Increased stiffness is observed in used MEAs relative to new MEAs, which indicates that hygro-thermal aging increases the brittleness of the material. A slight dependence on direction--that is, anisotropy--is also determined. [ABSTRACT FROM AUTHOR]

Abstract: A hygrothermal model for analyzing composite laminates under both mechanical and hygrothermal loadings is constructed by the variational asymptotic method (VAM). The original 3-D nonlinear, one-way coupled, hygrothermoelasticity problem is formulated based on a set of intrinsic variables defined on the reference plane and for arbitrary deformation of the normal line. Then the VAM is used to rigorously split the 3-D problem into two problems: a nonlinear, 2-D, plate analysis over the reference plane to obtain the global deformation and a linear analysis through the thickness to provide the 2-D generalized constitutive law and the recovering relations to approximate the original 3-D results. The nonuniqueness of asymptotic theory correct up to a certain order is used to cast the obtained asymptotically correct second-order free energy into a Reissner–Mindlin type model to account for transverse shear deformation. The present theory is implemented into the computer program, Variational Asymptotic Plate and Shell Analysis (VAPAS). Results from VAPAS for several cases have been compared with the exact hygrothermal solutions, classical lamination theory and first-order shear-deformation theory to demonstrate the accuracy and power of the proposed theory and use of VAPAS. The proposed theory can achieve an accuracy comparable to high-order layerwise theories with many more degrees of freedom at the cost of a first-order shear-deformation theory. [Copyright &y& Elsevier]

The effect of temperature and hygrothermal aging on the tensile properties of three types of anisotropic conductive films (ACFs) with different conductive particle percentages (4.69 vol.%, 6.14 vol.%, and 8.07 vol.%) are experimentally studied. Glass-transition temperatures of the three types of ACF are measured using a dynamic mechanical analyzer (DMA). The effect of the volume fraction of particles on the tensile properties is discussed. An increase in the volume fraction of the conductive particles enhances the Young’s modulus to some extent, but reduces the tensile strength. It is also investigated how hygrothermal aging impacts the tensile properties of ACFs at temperatures of 40°C, 80°C, and 120°C after aging times of 200 h and 1000 h. It is found that the mechanical properties of the ACFs basically decline with the hygrothermal aging time. [ABSTRACT FROM AUTHOR]

The transient residual stresses in polymer matrix composites induced by cyclic variations in temperature and moisture are very important and must be taken into account in the design of composite materials, particularly aerospace structures e.g. aircraft. Aiming to reduce these stresses, we have studied the influence of anisotropy on the hygrothermal behaviour of the laminated plates. The objective, here, is to contribute to the optimal design of composite structures. The anisotropy is evaluated using the degree of anisotropy introduced from polar representation of tensors . Various laminates, with controlled and random stacking sequences, were analysed under typical boundary conditions and with the same hygrothermal loading. The results show that the thermal and hygroscopic stresses vary differently with the degree of anisotropy in such a way that their superposition does not lead to a growth of the intern resulting stresses. The other obtained results show that the knowledge of the degree of anisotropy of the laminate permits us to predict the state of different stresses in the ply frame. [Copyright &y& Elsevier]

The aim of the research presented in the article was to check the differences in the hygro-thermal and mechanical properties of hemp-lime composites with different shives fractions, depending on the direction of mixture compaction. The research part of the paper presents the preparation method and investigation on the composites. Thermal conductivity, capillary uptake, as well as flexural and compressive strengths were examined. Additionally, an analysis of the temperature distribution in the external wall insulated with the tested composites was performed. The results confirm that the direction of compaction influences the individual properties of the composites in a similar way, depending on the size of the shives. The differences are more pronounced in the case of the composite containing longer fractions of shives. Both thermal conductivity of the material and the capillary uptake ability are lower in the parallel direction of the compaction process. Composites exhibit greater stiffness, but they fail faster with increasing loads when loaded in the direction perpendicular to compaction. [ABSTRACT FROM AUTHOR]

• Thermal expansion anisotropy in an interpenetrating metal/ceramic composites (IPC) is studied. • Composites with a wide range of ceramic contents are investigated. • Origin of the anisotropy is the processing induced structural features present in the IPC. • Thermal expansion coefficients of the IPC have been compared with micromechanical models. Thermal expansion behavior of an interpenetrating metal/ceramic composite having ceramic contents in the range of 34−60 vol.% is studied in this work. Four thermal cycles were carried out between room temperature and 500 °C at a constant heating/cooling rate of 5 °C/min. Both thermal strain and thermal expansion coefficient decrease with increasing ceramic content in the composite. Evolution of the thermal expansion coefficient with temperature shows anisotropic nature. At all ceramic contents, highest thermal strain and thermal expansion coefficient are obtained along the preform press direction. The extent of thermal expansion anisotropy depends upon both temperature and ceramic content in the composite. The evolution of the observed thermal expansion anisotropy has been attributed to the elastic anisotropy of the preforms and composites, considering as well the elastic-plastic flow behavior of the metallic matrix. The results have been compared with several analytical theoretical models. [ABSTRACT FROM AUTHOR]