Linear Expansion Research Articles

Functionally Gradient Material Fabrication Based on Cr, Ti, Fe, Ni, Co, Cu Metal Layers via Spark Plasma Sintering

The paper presents a method of obtaining functionally graded material (FGM) of heterogeneous (layered) type based on joined metals Cr-Ti-Fe-Co-Ni-Cu using spark plasma sintering (SPS) technology. The structure, elemental and phase composition of FGM obtained on the basis of joined metals with different values of the temperature coefficient of linear expansion (CTLE) were studied by SEM, EDS and XRD methods with regard to the phase states of the alloy system. Based on the Vickers microhardness data, the evaluation of the mechanical characteristics of FGM in the whole sample body and locally at the contact boundaries of the joined metals was carried out. The results of the study are new and represent a potential for FGM, as well as functionally graded coatings (FGC), which have special physical, chemical and mechanical properties and are highly demanded for the manufacture of structures and products for industrial applications.

Гнездовые группировки орлов на ключевой орнитологической территории «Чинк Донызтау» в 2022 году

Гнездовые группировки орлов на ключевой орнитологической территории «Чинк Донызтау» в 2022 году

A hybrid artificial bee colony algorithmic approach for classification using neural networks

Artificial neural networks are an integral component of most corporate and research functions across different platforms. However, depending upon the nature of the problem and quality of initialisation values, the usage of standard stochastic gradient descent always risks the possibility of getting trapped in local minima and saddle points for smaller neural networks in particular. One way to overcome this is by using algorithms with proven global search capabilities to train the network. This allows the neural net to reach the optimum values for weights regardless of the initialisation parameters used during training. Two algorithms are proposed based on modifications to the original artificial bee colony algorithm and their performances are analysed extensively on three benchmark datasets of increasing complexity. The first (NMABC), employs neural network appropriate initialisation and linear search space expansion. This is integrated into the second (LHABC), and incorporates stochastic gradient descent into the employed phase of the bees for faster convergence. It is found that the proposed algorithms consistently outperform standard approaches in all cases.

The Non-Commutative Korteweg—De Vries Hierarchy and Combinatorial Poppe Algebra

We give a constructive proof, to all orders, that each member of the non-commutative potential Korteweg-de Vries hierarchy is a Fredholm Grassmannian flow and is therefore linearisable. Indeed we prove this for any linear combination of fields from this hierarchy. That each member of the hierarchy is linearisable, and integrable in this sense, means that the time evolving solution can be generated from the solution to the corresponding linear dispersion equation in the hierarchy, combined with solving an associated linear Fredholm equation representing the Marchenko equation. Further, we show that within the class of polynomial partial differential fields, at every order, each member of the non-commutative potential Korteweg--de Vries hierarchy is unique. Indeed, we prove to all orders, that each such member matches the non-commutative Lax hierarchy field, which is therefore a polynomial partial differential field. We achieve this by constructing the abstract combinatorial algebra that underlies the non-commutative potential Korteweg-de Vries hierarchy. This algebra is the non-commutative polynomial algebra over the real line generated by the set of all compositions endowed with the Poppe product. This product is the abstract representation of the product rule for Hankel operators pioneered by Ch. Poppe for integrable equations such as the Sine-Gordon and Korteweg-de Vries equations. Integrability of the hierarchy members translates, in the combinatorial algebra, to proving the existence of a `Poppe polynomial' expansion for basic compositions in terms of `linear signature expansions'. Proving the existence of such Poppe polynomial expansions boils down to solving a linear algebraic problem for the expansion coefficients, which we solve constructively to all orders.

セルロースナノファイバーコンポジットの高分散技術とその特徴

Cellulose Nano Fibers (CNFs) is expected to be utilized in various fields because of its attractive properties such as high strength, high rigidity, and low coefficient of linear expansion. CNFs have attracted significant attention as materials that can enhance the mechanical properties of polymers. CNFs can easily form hydrogen bonds between CNFs because of the many hydroxyl groups on the surface of a CNF. Therefore, in many cases, CNF agglomerates with diameters greater than 100 µm remain in a composite when compounded with hydrophobic polymers. Recently, we can success in preparing the dry powders of CNFs by coating of hydrophobizing agent and special drying (trial products by Sugino Machine ; 20 nm of fiber diameter, 1 and 10 µm of fiber length) . The CNFs are easily dispersed in a polypropylene (PP) matrix by melt-compounding with using a twin-screw extruder. No agglomerates of CNFs with diameters greater than 1 µm can be found in the composite by optical microscope observations and TEM observations of electron staining ultrathin section.

Structure, magnetism and low thermal expansion in Tb1-xErxCo2Mny intermetallic compounds

Here, we obtained a series of controllable thermal expansion alloys Tb1-xErxCo2Mny (x = 0-0.5, y = 0-0.4) by incorporating double rare earth doping and introducing non-stoichiometric Mn content. By varying the amount of Er or Mn, a low thermal expansion (LTE) is achieved in Tb0.6Er0.4Co2Mn0.1 (TECM, α1 = 1.23 × 10-6 K-1, 125~236 K). The macroscopic linear expansion and magnetic properties reveal that anomalous thermal expansion is closely related to the magnetic phase transition. Synchrotron X-ray powder diffraction results show that TECM is a cubic phase (space group: Fd-3m) at high temperatures, and a structural transition to a rhombohedral phase (space group: R-3m) occurs as temperature decreases. The negative thermal expansion c-axis compensates for the normal positive thermal expansion of the basal plane, resulting in the volumetric LTE. This study provides a new metallic and magnetic ZTE material.

PRODUCTION OF FUNCTIONALLY GRADIENT MATERIALS BASED ON SILICON CARBIDE AND HIGH-ALLOY STEEL USING SPARK PLASMA SINTERING TECHNOLOGY

An important scientific task of practical materials science is the production of metal-ceramic composites in the form of functional gradient materials (FGM) for special-purpose products. In this regard, a study was conducted on the application of spark plasma sintering (IPS) technology for the effective diffusion connection of SiC ceramics and high-alloy steel (grade X18R15) to obtain a combined FGM composite. In a comprehensive experimental study, the dynamics of consolidation and changes in the phase composition of dispersed SiC under conditions of different temperatures and heating rates, pressing pressure, and holding time were studied. As a result, the IPS conditions were optimized for obtaining SiC ceramics of high relative density (82%) and microhardness (500 HV) of stable phase composition. The physicochemical foundations of the formation of a strong compound of a two-component SiC-ceramic and steel system under IPS conditions without additives and using a mixture of additives in the form of a binder, a reaction binder and a damper (Ti–Ag, Ti–TiH2, Ti–Ag–TiH2 and Ti–Ag/Mo additive systems) have been studied. The structure, composition of ceramics and intermediate (binding and damping) layers, as well as the diffusion of elements at the boundary of the formed compounds in FGM composites, were studied using XRF, SEM and EMF methods. It was found that the Ti–Ag/Mo additive in the ratio of 30 wt. % Ti–70 wt. % Ag and a dense layer of Mo (thickness ~ 2 mm), acting as a damper to compensate for the temperature coefficient of linear expansion, ensure the formation of a connected FGM composite of an integral shape. The presented studies have been implemented for the first time, are promising and require further development in order to gain scientific knowledge of the manufacture of composite products for special purposes.

Dependence of hardness and other properties of gray iron on its carbon equivalent and degree of eutecticity

The chemical composition, carbon equivalent and properties of castings from unalloyed and low-alloyed gray irons with lamellar graphite of various grades from СЧ100 to СЧА400 were analyzed in accordance with DSTU 8833:2019. There is a reference to such cast iron in the technical conditions for brake pads made of composite materials (rubber mixtures), in particular, for the production of cast iron inserts. Other products for railway transport are also made from cast iron СЧ350, for example, the friction “Khanin wedge”. It is shown that in industrial batches of the “Khanin wedge”, cast from cast iron СЧ350, the hardness did not correlate either with the content of elements in the chemical composition of the cast iron, or with the carbon equivalent due to the narrow range of its values even within the cast iron of the same grade. According to DSTU 8833:2019, with an increase in the carbon equivalent in the possible regulated range of values (%) from 3.03 to 4.54, the Brinell hardness of HB monotonically decreases by approximately 1.54...1.57, and the coefficient of thermal conductivity increases by almost one and a half times. Reducing the sulfur content in the chemical composition from 0.20 to 0.05 % of CH350 cast iron significantly reduces the range of dispersion of the carbon equivalent. The parameters (mean values, mean square deviations and coefficients of variation) of the carbon equivalent and the degree of eutecticity of the chemical composition of cast irons with lamellar graphite of brands from СЧ100 to СЧА400 were determined by means of statistical tests using the Monte Carlo method. It is shown that due to the significant dispersion of the values of the carbon equivalent of the chemical composition, hardness, coefficient of thermal conductivity, strength, density, modulus of elasticity, linear shrinkage, heat capacity, coefficient of linear expansion of cast iron with lamellar graphite of grades from СЧ100 to СЧА400 according to DSTU 8833:2019, it is necessary from the specified list grades of cast iron to determine and regulate in the technical conditions for composite brake pads a specific grade of cast iron intended for the manufacture of inserts in such pads.

The Influence of Cryogenic Treatment on the Microstructure and Mechanical Characteristics of Aluminum Silicon Carbide Matrix Composites

Aluminum matrix composites have been widely used in aerospace and automotive fields due to their excellent physical properties. Cryogenic treatment was successfully adopted to improve the performance of aluminum alloy components, while its effect and mechanism on the aluminum matrix composite remained unclear. In this work, the effects of cryogenic treatment on the microstructure evolution and mechanical properties of 15%SiCp/2009 aluminum matrix composites were systematically investigated by means of Thermoelectric Power (TEP), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). The results showed that TEP measurement can be an effective method for evaluating the precipitation characteristics of 15%SiCp/2009 aluminum matrix composites during aging. The addition of cryogenic treatment after solution and before aging treatment promoted the precipitation from the beginning stage of aging. Furthermore, the aging time for the maximum precipitation of the θ″ phase was about 4 h advanced, as the conduction of cryogenic treatment accelerates the aging kinetics. This was attributed to the great difference in the linear expansion coefficient between the aluminum alloy matrix and SiC-reinforced particles, which could induce high internal stress in their boundaries for precipitation. Moreover, the lattice contraction of the aluminum alloy matrix during cryogenic treatment led to the increase in dislocation density and micro defects near the boundaries, thus providing more nucleation sites for precipitation during the aging treatment. After undergoing artificial aging treatment for 20 h, the increase in dispersive, distributed precipitates after cryogenic treatment improved the hardness and yield strength by 4% and 16 MPa, respectively.

Jensen-ANN: A Machine Learning adaptation of Jensen Wake Model

Wake models play an important role in wind farm layout optimization and control studies and it is, therefore, important to model wake effects in accurate and efficient ways. The power production from a wind farm is estimated using analytical models such as Jensen model in the wind industry, as they are simple and their computational cost is significantly less compared to the high-fidelity models involving Large Eddy Simulations. As these analytical models are used in an iterative setup like control and optimization of wind layouts, simulation cost involved in these models is extremely important. However, most of the analytical models assume linear expansion of wake while modeling wake effects, which makes it inaccurate. In this paper, the authors present a data driven approach under the framework of machine learning to impart the effect of nonlinear expansion of wake in the analytical models and thereby empowering them to be more accurate. Such a wake model was developed by integrating Artificial Neural Networks (ANNs) and Jensen model, where the expansion of wake is assumed as nonlinear and is modeled using ANNs inside the Jensen model setup, thus establishing the nonlinearity between inter-turbine distance and reduction in wind speed. To prove the efficacy of the proposed model, the results are compared with the predictions of analytical Jensen model, and it has been shown that the proposed model performs better than Jensen, demonstrating the importance of nonlinear expansion of wake and its effect in power calculation of a wind farm.

Preparation and characterization of diphenyl silicone rubber/microfiber glass wool composite thermal control films.

Innovative research on the development of thermal control films for spacecraft surfaces is presented. A hydroxy-terminated random copolymer of dimethylsiloxane-diphenylsiloxane (PPDMS) was prepared from hydroxy silicone oil and diphenylsilylene glycol by a condensation reaction, and then liquid diphenyl silicone rubber base material (denoted as PSR) was obtained by adding hydrophobic silica. Microfiber glass wool (MGW) with a fiber diameter of ∼3 μm was added to the liquid PSR base material, which upon solidifying at room temperature, formed a 100 μm thick PSR/MGW composite film. The infrared radiation properties, solar absorption, thermal conductivity, and thermal dimensional stability of the film were evaluated. Moreover, the dispersion of the MGW in the rubber matrix was confirmed by optical microscopy and field-emission scanning electron microscopy. The PSR/MGW films exhibited a glass transition temperature of -106 °C, thermal decomposition temperature exceeding 410 °C, and low α/ε values. The homogeneous distribution of MGW in the PSR thin film resulted in a notable reduction in its linear expansion coefficient, as well as its thermal diffusion coefficient. Consequently, it exhibited a significant capacity for thermal insulation and retention. For the sample with 5 wt% of MGW, the linear expansion coefficient and thermal diffusion coefficient at 200 °C were reduced to 0.53% and 2.703 mm s-2, respectively. Thus, the PSR/MGW composite film has good heat-resistance stability and low-temperature endurance, along with low α/ε values and excellent dimensional stability. Additionally, it facilitates effective thermal insulation and temperature control, and can be an ideal material for thermal control coatings on spacecraft surfaces.

Stress-strain state of combined steel-FRP reinforced concrete beams

Steel reinforcements in reinforced concrete structures are susceptible to corrosion under different exposure conditions. This can lead to some disadvantages, including concrete deterioration, reduced long-term service life, increased cost of the structure due to re-strengthening measures, and reduced overall durability of the structure. In order to solve these problems, the issue of comprehensive use of Fiber reinforced polymer (FRP) reinforcements as an alternative to steel bars is urgent. FRP reinforcements have specific advantages including corrosion resistance, high tensile strength, density four times lighter than steel, and also linear expansion coefficient under the influence of temperature is small like concrete. In order to increase the load bearing capacity and ductility, it is recommended to effectively use steel rebar together with FRP rebar as a combination reinforcement, taking into account brittleness characteristic of FRP reinforcement and low modulus of elasticity. In this article, concrete beams with combined reinforcement are modelled by using ANSYS Workbench 2022 software. By testing virtual model, deflection corresponding to the value of the applied load on the beam, compressive and tensile stresses in the concrete, and stresses in FRP and steel reinforcement located in the tension zone were determined and analyzed.

Powder-bed-based 3D printing with cement for sustainable casting

3D printing allows for the cost-effective fabrication of moulds and can cast complex shapes. In this study, alumina cement and fine aggregates for refractories were used as the main raw materials, and saturation was adjusted to an appropriate level to control the cement binder mixture for sand casting. For cast iron, the mould must withstand temperatures of up to 1400 °C and must exhibit sufficient strength, gas permeability, and thermochemical durability at high temperatures. To accomplish these requirements, 3D printing powder was prepared by adjusting the ratio of fine aggregate (D50: 30 μm) and an even finer cement component (D50: 4 μm). To improve the moulding quality, a green body was used to optimise the cement admixtures to increase the strength, and the saturation level of the 3D printer was adjusted for dimensional accuracy. The high-temperature durability of the mould was evaluated by measuring its strength after heat treatment, using Simultaneous Thermal Analysis (TG-DSC), and through dimensional stability assessment. In addition, the pores of the specimens were analysed through microscale X-ray tomography. The surface resolution and tolerance of the final casting were determined by a 3D image roughness test using a surface roughness scanner. The cement exhibited the shortest curing time and the highest strength when the mass ratio of CA (CaO·Al2O3) to C12A7 (12CaO·7Al2O3) was 8:2. The final mixing mass ratio of cement to the fine aggregate was 8:2, which was determined based on the relationship between flowability and powder bed surface quality. The results proved the high-temperature thermal stability of the 3D-printed mould, which showed a total mass reduction of less than 3% and a low coefficient of linear expansion up to 1300 °C. Consequently, the suitability of the 3D-printed moulded body, composed of casting sand with cement as a binder, for casting at temperatures >1400 °C was demonstrated. Additionally, the final printed porous mould de-powdered easily, and its recyclability was verified by strength testing various mass ratios of fresh and recycled powder. Therefore, through optimisation of the material combinations and adjustment of the 3D printing process parameters, optimal gas permeability and moulding resolution could be achieved without any casting defect, while maintaining handling strength. The findings of this study demonstrate the potential of expanding the scope of powder-bed-based 3D printing of cement material to the casting market.

Symmetry-reduced dynamic mode decomposition of near-wall turbulence

Data-driven dimensionality reduction methods such as proper orthogonal decomposition and dynamic mode decomposition have proven to be useful for exploring complex phenomena within fluid dynamics and beyond. A well-known challenge for these techniques is posed by the continuous symmetries, e.g. translations and rotations, of the system under consideration, as drifts in the data dominate the modal expansions without providing an insight into the dynamics of the problem. In the present study, we address this issue for fluid flows in rectangular channels by formulating a continuous symmetry reduction method that eliminates the translations in the streamwise and spanwise directions simultaneously. We demonstrate our method by computing the symmetry-reduced dynamic mode decomposition (SRDMD) of sliding windows of data obtained from the transitional plane-Couette and turbulent plane-Poiseuille flow simulations. In the former setting, SRDMD captures the dynamics in the vicinity of the invariant solutions with translation symmetries, i.e. travelling waves and relative periodic orbits, whereas in the latter, our calculations reveal episodes of turbulent time evolution that can be approximated by a low-dimensional linear expansion.

NUMERICAL ANALYSIS OF STRESS AND STRAIN STATE IN MEMBRANE WALLS WELD JOINTS PERFORMED BY SUBMERGED ARC WELDING

The article presents investigation on stress and strain state in weld joints of boiler membrane wall by performing numerical analysis (finite element method). The main purpose was to create 3D model which will correspond to real membrane wall geometry under consideration, which will allow to perform strength simulation of numerical models considering variable parameters depending on the temperature. The model was fragment of boiler membrane wall made of X10CrMoVNb9-1 pipe and 10CrMo9-10 flat bar welded with submerged arc method. The research included the assumption of boundary conditions such as temperature cycles, welding method, type of mounting and base materials or heat treatment cycle. Three simulations have been performed depended on base material and temperature cycle adopted. As a result of the simulations, the distribution of temperature, displacement and stress in analyzed cases were obtained. The numerical simulation in dissimilar welded joints X10CrMoVNb9-1 pipe and 10CrMo9-10 flat bar heat treated afterwards, showed that the differences in linear expansion coefficients favour the development of cracks in the welds caused by increased level of stress. In parallel materials used for boiler membrane walls are the reason for difficulties in determine the proper technology of welding, preheating temperature and post-weld heat treatment parameters. Simulations indicated that the state of stress in weld joint is dependent on type of parameters adopted, and in closest scenario to real conditions, simulation showed that post-weld heat treatment had no positive effect on the stress state caused by discrepancy in linear expansion coefficients of both base materials.

THE RELATIVISTIC OBSERVER: Consequences of a Linear Expansion of Spacetime

Communication Dynamics Theory, defined in a companion paper, offers a new approach to understanding Spacetime. In Communication Dynamics Theory, physical reality is assumed to arise from an anisotropic expansion of a one-dimensional communication network. In this paper, we perform a first approximation mathematical transformation of the theory into hyperbolic geometry. The resulting model provides a potential basis for developing insight pertaining to previously poorly understood fundamental constants of physics. As a demonstration, we define a proton, neutron, and electron, demonstrate the emergence of observable space and time, and generate heuristic estimates of Euler’s number, the fine structure constant, and π, as well as geometric descriptions of fundamental forces of nature, occurring as natural consequences of the linear dynamic expansion of Spacetime.

THE INFLUENCE OF HIGH-MODULUS CARBON FIBER ON THE STRUCTURE OF POLYETHER ETHER KETONE

Nowadays, polymer-based carbon-plastics confidently displace common tribotechnical and structural materials (steel, aluminum, titanium, etc.) in the automotive, metallurgical, and agricultural industries. It happens due of the fact that carbon-plastics surpass steel and aluminum 5 and 7 times, respectively in terms of strength, and they are also characterized by low weight and ease of processing. An equally important factor is the possibility of manufacturing parts of various geometric shapes in one molding cycle, which also affects the attractiveness of using carbon plastics. In addition, products made of carbon plastics are characterized by low coefficients of friction and thermal linear expansion, high resistance to fatigue damage, mechanical shocks, solar radiation, corrosion, moisture, and high temperatures, while simultaneously reducing energy consumption during production 3—20 times. All the listed advantages of carbon plastics result from the interaction between the filler and the polymer matrix, which leads to a change in the structure of the materials. That is why studying this interaction and structure as a whole is an important step in the development of new materials. It is known from literary sources that its structure has a significant influence on the functional properties of a polymer composite: an increase in the degree of crystallinity leads to an increase in the strength, rigidity, and heat resistance of the polymer material. Considering the above, the purpose of the work was to study the influence of carbon fiber on the degree of crystallinity of polyether ether ketone. The article presents the results of X-ray analysis of carbon plastics based on Victrex150 G polyether ether ketone. The impact of compression moulding on the structure of composites is analyzed. It is shown that the carbon fiber structure is organized due to consolidation, while the processing of tableted samples into products by the method of compression moulding. The dependence of the crystallinity of carbon plastics on the content of Toray T700 carbon fiber is given. The expediency of conducting additional tests is shown to establish the influence of technological factors of compression moulding (temperature, load, exposure), as well as fiber length on the radiographic structure of the designed composite

Heat physical properties of polymer composites based on polychlortrifluoroethylene filled with thermally expanded graphite

Based on research and comparative analysis of heat physical (specific heat capacity cp, thermal coefficient of linear expansion a) properties of systems polychlorotrifluoroethylene (PCTFE) - nanodispersed thermally expanded graphite (TEG) and PCTFE - nanomodified silicon dioxide (SiO2) TEG (30% SiO2 for 70% TEG) the influence of the structural-morphological state of the components and their concentration, the level of interfacial interaction on the physical properties of nanocomposites has been studied.
 It is established that the double effect of the modified nanofiller on the crystalline component of the matrix structure is that a more developed crystal structure is formed in the polymer-modified nanofiller interaction zones and, conversely, some amorphization in the peripheral zones. At the same time, increasing the concentration of the modified nanofiller leads to competition from the growth of neighboring crystallites and the ability to fix macromolecules “from both ends” on the particles of the modified nanofiller. Whereas in the case of unmodified dispersed TEG the existence of such competing factors led to their mutual compensation and, as a consequence, stabilization of reflex temperatures after reaching the percolation threshold and exceeding the percolation threshold, in the case of modified nanofiller when polymer-filler interactions percolation of the second factor predominates, which leads to a decrease in the temperatures of the corresponding reflexes almost to their values, which correspond to a pure matrix.
 The work found that depending on the nanofiller concentration, the structure of the matrix and the system as a whole shows a transformation in the size of the inhomogeneity and change in the size of the inhomogeneity of the system structure is associated with the transition from inhomogeneity as the size of crystallites, the growth of which is activated by nanofiller at low concentrations, through the percolation threshold, to inhomogeneities associated with coagulation of nanoparticles at concentrations exceeding the percolation threshold. Thus the case of nanofillers, it is not advisable to use concentrations that significantly exceed the percolation threshold, as this leads to coagulation of the filler particles and the corresponding loosening of the matrix.
 It is also shown that modification of the nanofiller (TRG/30%SiO2) increases intermolecular interaction in the filler-matrix system. Depending on the concentration of the filler, the structure of the matrix and the system as a whole demonstrates dynamic transformations in the size of the heterogeneity of the structure. Also, research results show that modified nanofiller is more active against the polymer matrix than unmodified, which is a consequence of the fact of the double action of the modified nanofiller on the matrix structure is manifested, which consists in the formation of a strong crystalline structure in the zones of influence of the nanofiller and amorphization of the matrix in the peripheral zones

Possibilities of Integrated Fabrication of Insulation Systems in Electric Drives by Injection Molding of Thermosets.

Due to the increasing demand for electro mobility and specifically for electrified vehicles, the demand for electric drive technology is expanding significantly with changing requirements in terms of the process and the application. The electrical insulation system of the stator is an essential part of the fabrication process with a high impact on the application properties. Due to limitations-for example, in terms of suitable materials for the stator insulation-a new technology of integrated fabrication by injection molding of thermosets has been founded. In this study, two epoxy (EP) types with different fillers were investigated to prove their suitability in terms of the material properties in the fabrication process and the application. A general realization of the integrated fabrication of insulation systems in electrical engineering by injection molding was proved. Further, the differences regarding the suitability of the two materials are portrayed. It was demonstrated that mainly the filler material influences the fabrication process and the properties in the application, leading to differing suitability in terms of the EP 3162 EMG within the fabrication process and in terms of XW 6640-1 within the application properties of the thermal conductivity and the thermal linear expansion. It was further shown that the filler within the material system is required to increase the thermal conductivity needed for the application. The inclusion of the filler influences the reaction kinetics and the viscosity behavior. A fabrication of the material with fillers is however still possible.

Probabilistic Analysis of Strip Footings Using the Subset Simulation Approach and the Influence of Spatial Variability of Two Clay Layers

Abstract This article studies the probabilistic analysis at the ultimate limit state (ULS) of a strip footing resting on a purely cohesive soil composed of two layers with spatial variability of the upper or lower layer and treats the simultaneous effect of the variability of the two layers on the probability of failure Pf value using the subset simulation approach. The results are examined by comparing the Pf values obtained with the Pf value corresponding to the reference case of two homogenous clay layers. In general, the subset simulation approach is used in cases of uncertain parameters modeled by random variables. But in this paper, it is employed with uncertain parameters modeled by random fields because the spatial variability of soil properties strongly affects the behavior of geotechnical structures and causes a significant change in the variability of their responses. The soil cohesion parameter is modelled as a non-Gaussian (log-normal) anisotropic random field using a square exponential autocorrelation function by the optimal linear expansion estimation (EOLE) and the deterministic model is based on numerical simulations using the finite difference software FLAC3D.