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This work aims to make a unique polymer to be used as a conductive and flexible chip antenna. Its properties are robustness, rigidity, stretchability, and good conduction. The fabricated composite is composed of two copolymers, Polydimethylsiloxane (PDMS) and Polyethylenimine (PEI), assembled with nano metals (Copper, Silver), and graphene nanoparticles as a matrix. Nano metals fill out the inter-layer space, and polymer voids reinforce the cross linker. Graphene/metal nanoparticles help make chelating complexes using metallic bonds, enhancing the polymer’s conductivity from 1.87 × 10-4 to 5.64 ×10-6 σ Scm-1. The conductivity, self-healing, and surface morphology of fabricated composite are analyzed using different spectroscopic techniques, such as electrochemical impedance (EIS), Scanning Electronic Microscopy (SEM), Transition Electronic Microscopy (TEM), Infrared spectroscopy (IR), UV-Visible spectroscopy (UV), and a particle size analyzer.

Today, Wearable devices have been getting more attention in all life fields. Due to their unique characteristics like easier carriers, flexibility, durability, and biodegradable materials furthermore low-cost fabrication. in this...

Every year hundreds of serious accidents and catastrophic are accompanied by mining sector services as disaster, flooding, and demolition. To reduce the severity of the results such as high death numbers, lost communication inner and out mining, we have to find an easy way to improve communication means during that problems. In this paper, we reach out to fabricate durable, flexible, and wearable chaps, in addition to an easier carrier with highly efficient receiving and sending a signal at 2.4 GHz broad wide band. By doping a bunch of unique conductive metals (silver, copper, and gallium indium alloy) assembled on Graphene, its integration inside Polydimethylsiloxane to be future applicable antenna. Furthermore, we studied the physical and electric properties of a composite including Electrochemical Impedance properties (EIS), cyclic voltammetry (CV), and its thermal stability chip (DSC), as well as, using Transmission electron microscopy (TEM), and, scanning electron microscopy (SEM) techniques to clarify the surface morphology of fabricated materials. In addition to various measurements had been carried out such as Ultraviolet-visible, inductively coupled plasma (ICP) spectroscopy, and Energy-dispersive X-ray spectroscopy (EDX) to reinforce and elucidate the solid-state of ions inside fabricated Antenna. On the other hand, throughout stress-strain for the stretchability of fabricated is expanded to 30% of its original length, in addition to thermal stability reached to 485°C compared to pure PDMS substrate, with enhancing electric conductivity of composite ship.

Dielectric heating is a promising process for the uniform sterilization of food products as well as for the drying of products. However, radio frequency heating of wood-based materials (a highly anisotropic material with temperature, moisture and structural orientation dependent properties) does not seem to be elucidated in the literature. It is within this framework that this study is carried out and concerns the modeling of anisotropic dielectric heating by radio frequency (RF) and its application to the thawing of frozen wood. The nonlinear heat conduction problem involving phase changes is formulated in terms of volume enthalpy. For the numerical resolution of the thermal conduction equation, the finite element method is considered. Thermophysical and dielectric properties are expressed as a function of temperature, moisture content (MC), and structural orientation. The numerical approach is further validated by a combination of the analytical, numerical and experimental analyses. Finally, the effect of RF on the thawing of the Douglas-fir (Pseudotsuga menziesii) and the white oak (Quercus alba), which are two North American wood species, was studied based on an initial temperature of − 20 °C and a frequency of 50 MHz. In this regard, two MC of 65% and 90% are considered. For the two species of the studied wood, it is observed that the RF induce a uniform temperature profile.

In the veneer and plywood industry, the softening of a log, for better cutting (or unrolling), is generally done by immersing it in hot water (at a constant temperature). Accurate estimation of the heating time to reach a target temperature, at a given location in the log, is crucial, especially when the log is frozen. It is within this framework that this work is inscribed and it concerns four Canadian wood species: trembling aspen (Populus tremuloides), white birch (Betula papyrifera), yellow birch (Betula alleghaniensis) and sugar maple (Acer saccharum). The thermo-physical properties of the wood species are dependent on moisture content (MC), specific gravity (SG) temperature (T) and the structural directions (L,R,T). The initial temperature is − 20 °C and the target temperature, in the center of the log, is 60 °C. For the modeling of thermal conduction in the wood, the new approach 3D hybrid finite element enthalpy was used.

The aim of this work is to study the mechanical behavior of a hybrid composite based on polyester thermoset matrix reinforced by a mixture of Luffa (LF) and Glass (GF) fibers. The whole volume fraction of the fibers was limited to 20 vol% in which the LF fraction was varied from 5 vol% to 20 vol%. Composites plates were prepared using the resin transfer molding (RTM) method. The morphology was studied by scanning electron microscopy (SEM), and the mechanical properties of the composites were characterized using tensile, three points’ flexural tests and hardness. Obtained results have shown that the mechanical properties of the hybrid composites were superior to those of polyester/LF composite. The mechanical properties depend on the GF fraction and on the organization of GF and LF sheets in the composite. The analytical modeling of tensile properties showed that the mechanical behavior of these hybrid composites is better described by the model of Hirsch with an adjustable value between 0.37 and 0.55. In addition, the water absorption behavior of these hybrid composites was also investigated during 200 h.

In this work, the preparation and the physical evaluation of a series of miscible 0.2 M solutions in 50/50 volume ratios were addressed. A total of five solutions comprised of plain electrolyte/graphene, plain electrolyte/graphene-ethylene Glycol, plain electrolyte/graphene-poly-ethylene glycol, plain electrolyte/graphene-glycerol, and plain electrolyte/Graphene–Polyethylenimine. were assembled with Ag, and copper nanoparticles. The physical properties were studied by electrochemical impedance spectroscopy, solution conductivity calculations, and viscosity and flexibility measurements, particle size distribution analyses. Surface morphology characterizations were done by transmission electron microscopy. A comparative approach of the physical properties between the five solutions serves as a guide to select the most appropriate fluid applicable to the upcoming device.

This paper deals with the numerical study of the axial and radial forces, the stresses, the strains, and the vibrations induced by a liquid flow through a high pressure multistage centrifugal pump. This is to improve its performances account for the material of the shaft and the impellers. Indeed, a model of a 4-stage centrifugal pump is developed from a design point. The continuity and Navier-Stokes equations are used for the liquid flow through the pump. Furthermore, the equations of stresses, strains and vibrations are applied for the shaft and the impellers. The obtained system of equations is solved by means of ANSYS including the CFX, the static structural analysis and the harmonic response to determinate the fields of velocity and pressure, the axial and radial forces, the stress, the strain, and the amplitudes and the frequencies of vibrations on the pump shaft. In addition, numerical simulations are accomplished to analyze the shaft behavior in terms of the axial and radial forces, the stresses, the strains and the vibrations induced by liquid flow. The outlet blade height, the flow rate, the number of the stages, the diffuser return vanes and the diffuser in the last pump stage are used as parameters for these simulations. Good trends are achieved comparing the obtained results with these found in the literature and these calculated using the classical equations of stresses and strains.

Our work aims to make a unique polymer to be used as a conductive and flexible chip antenna. Its properties are robustness, rigidity, stretchability, and good conduction. The fabricated composite is composed of two copolymers, Polydimethylsiloxane (PDMS) and Polyethylenimine (PEI), assembled with nano metals (Copper, Silver ), and graphene nanoparticles as a matrix. Nano metals fill out the inter-layer space, and polymer voids reinforce the cross linker. Graphene/metal nanoparticles help make chelating complexes using metallic bonds, enhancing the polymer’s conductivity from 1.87 × 10− 4 to 5.64 ×10− 6 σ Scm− 1. We analyze the conductivity, self-healing, and surface morphology of fabricated composite using different spectroscopic techniques, such as electrochemical impedance (EIS), Scanning Electronic Microscopy ( SEM), Transition Electronic Microscopy (TEM), Infrared spectroscopy ( IR), UV-Visible spectroscopy (UV), and a particle size analyzer.

Purpose Reliability plays an important role in the execution of the maintenance improvement and the understanding of its concepts is essential to predict the type of maintenance according to the equipment state. Thereby, a computational tool was developed and programming with VBA in Excel® for reliability and failure analysis in a mining context. The paper aims to discuss these issues. Design/methodology/approach The developed approach use the modeling of stochastic processes, such as the renewal process, the non-homogeneous Poisson process and less conventional method as the Bayesian approach, by considering Jeffreys non-informative prior. The resolution gives the best associated model, the parameters estimation, the mean time between failure and the reliability estimate. This approach is validated with the reliability analysis of inter-failure times from underground rock bolters subsystems, over a two-year period. Findings Results show that Weibull and lognormal probability distribution fit to the most subsystems inter-failure times. The study revealed that the bolting head, the rock drill, the screen handler, the electric/electronic system, the hydraulic system, the drilling feeder and the structural consume the most repair frequency. The hydraulic and electric/electronic subsystems represent the lowest reliability after 50 operation hours. Originality/value For the first time, this case study defines practical failures and reliability information for rock bolter subsystems based on real operation data. This paper is useful to the comparative evaluation of rock bolter by detecting the weakest elements and understanding failure patterns in the individual observation subsystems on the overall machine performance.

High-density polyethylene (HDPE) nanocomposites were prepared by a melting-compounding process with a polymethylsilsesquioxane (PMSQ) as nanofiller. In this process, the PMSQ nanoparticles were swollen in an organic solvent using a Ultra-Turrax system and sonication and blended with molten HDPE using a twin-screw extruder. This was followed by solvent removal. Nanocomposites with different PMSQ mass contents from 0 to 1% were prepared. The nanocomposites were characterized with Fourier transformed infrared, transmission electron microscopy, differential scanning calorimetry, scanning electron microscopy and by thermal conductivity. The mechanical and thermomechanical properties of the materials were studied. The HDPE–PMSQ nanocomposites presented a remarkable increase in the elastic modulus (E′) compared to the neat HDPE. The obtained mechanical and thermomechanical properties of HDPE–PMSQ nanocomposites were found to be related to the barrier effect of the PMSQ nanoparticles.

The anisotropic problem of thermal conduction in a solid is generally treated in a reference coordinate system, which adequately describes its thermal conductivity tensor (Cartesian, cylindrical or spherical). For this problem, numerical treatment is difficult, especially if the thermophysical properties are non-linear or if the anisotropic medium undergoes a phase change. In this paper, we propose an approach using a Cartesian reference system to treat the anisotropic thermal conduction of problems for which the solid medium is characterized by a set of tensors of thermal conductivity of different natures (Cartesian and/or cylindrical and/or spherical), with or without phase change. For this purpose, we the anisotropic thermal conductivity tensor, with respect to a cylindrical or spherical coordinate system, is transformed by an equivalent tensor into global Cartesian coordinates. The nonlinear heat conduction problem involving phase changes, such as wood freezing, is solved using hybrid three-dimensional volumetric specific enthalpy based on finite-element analysis. The proposed approach is validated with analytical testing for two anisotropic media and with two experimental tests related to the heating of frozen woods. As an application, we have numerically quantified, on the one hand, the minimum time required for the thaw and, on the other hand, the freezing of a log of wood, such as white pine, according to the length of its radius (7.5, 10, 15, 20 and 25 cm). The thermophysical properties are a function of temperature, moisture content and structural orientation.

Our work aims to make a unique polymer to be used as a conductive and flexible chip antenna. Its properties are robustness, rigidity, stretchability, and good conduction. The fabricated composite is composed of two copolymers, PDMS and PEI, assembled with nano metals (Cu, Ag), and graphene nanoparticles as a matrix. Nano metals fill out the inter-layer space, and polymer voids reinforce the crosslinker. Graphene/metal nanoparticles help make chelating complexes using metallic bonds, enhancing the polymer’s conductivity from 1.87* 10− 4 to 5.64*10− 6 σ Scm− 1. We analyze the conductivity, self-healing, and surface morphology of fabricated composite using different spectroscopic techniques, such as electrochemical impedance (EIS), SEM, TEM, IR, UV, and a particle size analyzer.

There is a growing interest in unmanned aerial vehicles (UAVs) or drones in the aviation industry, both for military and civil applications. They are deployed for border surveillance, transport of medicines, data collection, and access to places which present a risk to humans to name a few. The materials used so far in the manufacture of UAVs are wood, plastic, aluminum, and carbon fibers. However, the level of performance of wood–plastic composites is expected to allow them to compete with both plastic and wood for the manufacture of UAVs’ small blades. In this regard, a family of biocomposites based on high-density polyethylene reinforced with 0%, 20%, 30%, 40%, and 50% (w/w) sawdust particles were developed and characterized. Their viscoelastic properties were determined by oscillatory shear tests and their viscoelastic behavior characterized by the Lodge integral model. A numerical study, using the nonlinear explicit finite element method, was further carried out to evaluate their suitability for shaping the blades of the drone by the thermoforming process. The forming pressure required by the numerical analysis was derived from the Van der Waals real gas equation of state. The influence of the airflow on the thickness of the thermoformed part, as well as the stress and energy required for the process were analyzed. The results indicate that the constituent equations have a significant impact on the final stress distribution in the thermoformed part; furthermore, the time and energy required for the forming process is related to the degree of reinforcement of the thermoplastic matrix.

In this work, the preparation and the physical evaluation of a series of miscible 0.2 M solutions in 50/50 volume ratios were addressed. A total of 5 solutions comprised of plain electrolyte/ graphene, plain electrolyte / graphene-ethylene Glycol, plain electrolyte/ graphene-poly-ethylene glycol, plain electrolyte/ graphene-glycerol, and plain electrolyte/ Graphene–Polyethylenimine. were assembled with Ag, and copper nanoparticles. The physical properties were studied by electrochemical impedance spectroscopy, solution conductivity calculations, and viscosity and flexibility measurements, particle size distribution analyses. Surface morphology characterizations were done by transmission electron microscopy. A comparative approach of the physical properties between the fives solutions serves as a guide to select the most appropriate fluid applicable to the upcoming device.

Simulation of airbag and membrane deployment under pressurized gas problems becomes more and more the focus of computational engineering, where finite element methods (FEMs) for structural mechanics and finite volume for computational fluid dynamics are dominant. New formulations have been developed for fluid structure interaction (FSI) applications using mesh free methods as smooth particle hydrodynamic (SPH) method. Up to these days very little has been done to compare different methods and assess which one would be more suitable. For small deformation, FEM Lagrangian formulation can solve structure interface and material boundary accurately, the main limitation of the formulation is high mesh distortion for large deformation and moving structure. One of the commonly used approaches to solve these problems is the arbitrary Lagrangian Eulerian (ALE) formulation which has been used with success in the simulation of FSI with large structure motion such as sloshing fuel tank in automotive industry and bird impact in aeronautic industry. For some applications, including bird impact and high velocity impact problems, engineers have switched from ALE to SPH method to reduce central processing unit (CPU) time and save memory allocation. Both ALE and SPH methods are described and compared here using similar mesh size, each ALE element is replaced by an SPH particle at the element center. From different simulation, it has been observed that for the SPH method to provide similar results as ALE or Lagrangian formulations, the SPH meshing needs to be finer than the ALE mesh. A contact algorithm is performed at the FSI for both SPH and ALE formulations. A simulation of airbag membrane deployment generated by high pressurized gas is performed.

In many applications, metal gears have been replaced by plastic gears because of their functionality and cost advantages. Despite their many benefits, the intensive use of plastics and composites raises sustainability issues because of the depletion of non-renewable petroleum resources and the pollution that is generated. Thus, alternative ecological solutions for plastic gears are necessary; however, little is known regarding ecologically designed gears. In this study, we propose two types of innovative gear materials. The first is a semi-ecological polyethylene bio-composite gear reinforced with birch fibers, and the second is a fully bio-sourced natural polyethylene gear with birch fibers. This study is the first time such fully ecological composite-plastic gears have been tested. The tests record the evolution of the fatigue and temperature over time under various operating conditions. Furthermore, acoustic emission is used to assess the evolution of fatigue cracks. The results indicate that the fully ecological gears are feasible and offer an alternative to traditional materials, such as engineering plastics, likely at a lower cost.

In this work, laminated polyester thermoset composites based on palm tree fibers extracted from palms leaflets and glass mats fibers were manufactured to develop hybrid compositions with good mechanical properties; the mixture of fibers was elaborated to not exceed 25 vol.%. Samples were prepared with a resin transfer molding (RTM) method and mechanically characterized using tensile and flexural, hardness, and impact tests, and ultrasonic waves as a non-destructive technique. The water sorption of these composite materials was carried out in addition to solar irradiation aging for approximately 300 days to predict the applicability and the long-term performance of the manufactured composites. Results have shown that the use of glass fibers significantly increased all properties; however, an optimum combination of the mixture could be interesting and could be developed with less glass sheet and more natural fibers, which is the goal of this study. On the other hand, exposure to natural sunlight deteriorated the mechanical resistance of the neat resin after only 60 days, while the composites kept high mechanical resistance for 365 days of exposure.

The ladder polymethylsilsesquioxane (PMSQ) nanoparticles with average diameter size of 15 and 20 nm were synthesized by hydrolysis and condensation of methyltrimethoxysilane (MTMS). An ex situ kinetic study in acidic medium of MTMS hydrolysis was followed by Raman spectroscopy. The PMSQ nanoparticles was studied by infrared spectroscopy, 29Si and 13C nuclear magnetic resonance and by X-ray diffraction. The thermal stability was examined by thermogravimetric analysis. PMSQ nanoparticles have a degradation temperature of 390 °C under nitrogen and 380 °C under oxygen, an excellent specific area (397.21 m2/g), a density of 1.42 g/m3 and hydrophobic surface (apparent contact angle 148° ± 3).

For non-linear problems, the solution of the heat equation in terms of the Kirchhoff transformation, θ(T), is very limited. This restriction is due to the practical disadvantage of the inverse temperature shift from the Kirchhoff transform T(θ). In order to get around the difficulties associated with the representation of θ(T) and its inverse T(θ) for solids with strongly non-linear conductivities, a strategy based on a reverse engineering method is considered. It consists in identifying the number of knots and their respective locations on the curve T(θ) at the most efficient computational cost. In order to obtain the location of the knots, the curve is fitted by B-spline functions and the data is partitioned by an application of the bisectional method with a predetermined error. These knots are further optimized using the non-linear least squares method. The proposed approach can be combined with a numerical method such as the FEM, BEM, and FEV to provide the non-linear solution of the heat equation in terms of θ. However, in this work we have limited ourselves to the FEM. The validation of the proposed approach is achieved through several cases ranging from constant to strongly non-linear thermal conductivities with or without convection. As an application, the 3D finite element method is applied to determine the non-linear temperature distribution in a copper block with an imposed temperature.

This work reports the thermal degradation kinetics of five formulations of polyethylene terephthalate (PET) reinforced with 1, 5, 10, 15, and 20 % hemp fibers based on thermogravimetric investigations. Two consecutive degradation steps were observed between 573 and 773 K. Moreover, their kinetic triplets were determined by nonlinear curve fitting methods, with the Sestak–Berggren and the truncated Sestak–Berggren models, respectively. The resulting kinetic parameters varied with the fiber’s concentration in the following ranges: 1.8 ≤ A ≤ 5, 2.25 ≤ n ≤ 3.17, 7.05 ≤ m ≤ 12.74, and −2.21 ≤ p ≤ −1 for the first step; and 1.76 ≤ A ≤ 10, 1.37 ≤ n ≤ 2.49, and 0.77 ≤ m ≤ 2.35 for the second. This work further confirms the thermal stability of PET–hemp fiber composites and provides key information for the reaction mechanism, a crucial developmental step for bio-composite materials with high-melting thermoplastic matrices.

The mechanical and structural properties of five formulations of a novel melt processed poly-ethylene terephthalate (PET)-hemp fibers composite were determined, followed by a numerical investigation of their thermoformability using the ThermoForm® code. The composites' linear viscoelastic properties were determined by small amplitude oscillatory shear tests and their viscoelastic behavior characterized by the Christensen's model. The forming pressure load required by the numerical analysis was derived from the Redlich–Kwong's real gas equation of state. The air flow's influence on the thickness of the thermoformed part, as well as the stress and the energy required for the process were analyzed. Our observations indicate little influence of the constitutive equations of the investigated formulations on the final thickness distribution of the thermoformed part; moreover, the time and energy required for the process showed no clear variation with the fiber load. POLYM. ENG. SCI. 56:1021–1030, 2016. © 2016 Society of Plastics Engineers

In the present work, wood flour reinforced thermoplastic polymer composites, with and without coupling agents, were prepared by melt processing, and their mechanical and thermal behaviors were analyzed. For preparation of polymer composites, six different formulations were used. On the other side, the degradation of wood fillers up to 97 days and water uptake in composites up to 10 weeks was evaluated, respectively, using fungi specie (Gloephyllyllum trabeum) and water absorption tests. To study the morphological changes resulting from microorganism activity, scanning electron microscopy was used. The obtained results indicate that the addition of wood fillers to the polyethylene matrix increases the degree of crystallinity, and tensile strength. On the contrary, resistance to fungi decay and water absorption decrease as a function of the wood fillers content thus the composite becomes more vulnerable to moisture uptake and micro-organism attack, which can change the morphological and mechanical strength of composite. Based on the obtained results, microorganisms mainly affect the surface of composite and the adhesion of wood and polymer matrix. An optimized amount of filler content can reinforce the polymeric matrix more efficiently while decrease the rate of degradation of wood fillers as well. POLYM. COMPOS., 2015. © 2015 Society of Plastics Engineers

In the last decades, research on atmospheric icing of structures such as power transmission lines has attracted much interest. Accumulation and the shedding of atmospheric ice from overhead transmission lines and ground wires may cause their rupture and tower collapses, leading to power outages. The present work concerns a study of the compressive strength of atmospheric ice, under different experimental conditions such as strain rate, temperature, and porosity. For this reason, ice was accumulated in the closed loop wind tunnel at CIGELE (Industrial Chair on Atmospheric Icing of Power Network Equipment), under three temperatures (− 20, − 15 and − 5 °C). The wind speed inside the tunnel was set at 20 m/s in order to obtain a mean volume droplet diameter (MVD) of 40 μm and a liquid water content (LWC) of 2.5 g/m 3 . Each type of ice was tested at the same temperature at which it had been accumulated. A tomographic analysis was carried out on a small specimen (cylinder of 1 cm diameter × 2 cm length) for each temperature in order to quantify the porosity and determine the grain size and their distribution. The obtained results show a strong dependence of the compressive strength on temperature, strain rate and porosity. The ductile–brittle transition was identified within a strain rate ranging between 10 − 4 s − 1 and 10 − 3 s − 1 . It was found that compressive strength increases with decreasing temperature for deaerated ice. However, for atmospheric porous ice, compressive strength increases until − 15 °C, then decreases for lower temperatures. Compressive strength of atmospheric ice is highly dependent on porosity, which is related to the amount, size and distribution of pores inside the ice.

International audience; Wood polymer composites (WPC) have well proven their applicability in several fields of the plasturgy sector, due to their aesthetics and low maintenance costs. However, for plasturgy applications, the characterization of viscoelastic behavior and thermomechanical and thermophysical properties of WPC with the temperature and wood filler contents is essential. Therefore, the processability of polymer composites made up with different percentage of wood particles needs a better understanding of materials behaviors in accordance with temperature and wood particles contents. To this end, a numerical analysis of the viscoelastic, mechanical, and thermophysical properties of composite composed of high density polyethylene (HDPE) reinforced with soft wood particles is evaluated.

There is a need to correctly dimension gears for an application with an understanding of how the gear will deteriorate until final failure. However, this task has been difficult because engineers must consider the complexity of gear meshing phenomena combined with the gear material-specific properties and application particularities to determine the critical failure and maintenance points. This article provides a review of the multiple damage modes of plastic gears, including both general and plastic gear-exclusive modes. This article reviews the different branches of the damage problem, performs a combined solution of finite element analysis (FEA) and validated analytical equations for plastic gears. With this knowledge, a unique system of analysis of gear utilization perspectives that evaluates all possible damaging processes is built. By applying a range of normal loads on a plastic gear, it was verified that the damage mode depends highly on the applied load. The identification of the proper damage mode allows preventive actions to be taken because the limits of plastic gears and the optimal usage are identified. With this damage modeling strategy, the designer can skip several steps in reaching a decision regarding plastic gear applicability. This synthesis represents significant progress for plastic gear damage modeling because the major factors of plastic gear functioning and the damage factors are observed.

In contrast to numerical methods, which are generally poorly adapted to thermal conduction treatments in solid media containing different materials with different types of orientations of thermal conductivity tensors (Cartesian and/or cylindrical and/or spherical), the proposed new approach, 3D hybrid finite elements, is easier to implement numerically and, in particular, for the finite element method. To improve the efficiency and accuracy of the solution by FEM, we consider the implicit method using the prediction/correction strategy. The proposed approach is validated in the following cases: (i) two analytical tests for cylindrical and spherical anisotropic thermal conduction; (ii) numerical orthotropic thermal conduction in the case where the local axes of the material are not aligned with the global Cartesian axes (case of a square plate made of two different materials: one isotropic and the other orthotropic) and (iii) experimental temperature obtained on the heating of a cylindrical log. As applications, two multi-material and multi-orientation situations of the thermal conductivity tensor were considered: one related to an ignition pipe made of multiple anisotropic materials and the other to a heated chair-seat made of multiple anisotropic materials.

This work deals with a numerical study of the potential use of microwave radiation as a heating mode for the thermoforming of wood-plastic composites (WPC). It also shows the comparison between the infrared and microwave heating modes for polypropylene (PP) and PP-based bio-composite sheets. The latter contain PP with 30% wood-based reinforcements. The differentiating parameters between the investigated bio-composite sheets were their thicknesses and the size of their reinforcements. Their thicknesses were 1, 2, 5 and 10 mm, and the size of their reinforcements were 100, 200 and 500 μm. The target heating temperature is 140 °C on the outer surfaces of the sheets. The results indicate that the microwaves generate a closely uniform temperature distribution in the sheets. Meanwhile, the minimum heating time is found for the bio-composites, which is 1 mm thick for the infrared mode, and the bio-composites whose reinforcements are 200 μm for the microwave mode.

In this study, we have explored the numerical modelling of the thermoforming of high-density polyethylene wood particle composites (WPC) into a formwork intended for construction applications. By using the parameters identified from oscillatory shear test, the Lodge model is used to describe the viscoelastic behavior of the WPC sheet. The forming stage of the WPC sheet is performed under the action of gas flow governed by the van der Waals equation of state. The thermoformability is firstly determined by simulating a free blowing of HDPE and highly charged WPC. Then, the numerical simulation of the formwork thermoforming is carried out on four types of WPC. The results have shown that the structure is subjected to increasing stress as the wood particle content increases, which consequently increases the risk of failure. Nevertheless, thermoforming is possible for WPC sheets with less than 40 % wood content. Simulations of the formwork under loadings have also shown good mechanical resistance at low thicknesses.

This paper addresses the problem of distributing uniformly the energy flux intercepted by a thermoplastic sheet surface during the infrared radiation. To do so, we discretized this problem and then formulated it as an integer linear programming problem, for which we applied two meta-heuristic algorithms namely the simulated annealing algorithm (SA) and harmony search algorithm (HSA), in order to minimize the corresponding objective function. The results produced by the numerical study we conducted on the performance of both algorithms are presented and discussed.