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Wood plastic composites (WPC) are a form of composites made by combining wood particles/flour with polymers. The Mechanical properties of Wood Plastic Composites mainly depends on the composition of its matrix (Polymers), reinforcements (Saw dust), coupling agents and lubricants. Generally, the polymer of the matrix in WPCs is made of a single monomer such as HDPE, PP, PS, PET etc. The Objective of the project is to investigate the mechanical properties of a Wood Plastic Composite by using polymer blend (combination of two or more polymer) as a matrix and its effects on mechanical properties of WPC by varying the composition of the mixture at various proportions.

The contribution shows a wireless framework developed on the cost-effective Arduino hardware platform and used for measurements of cementitious composites. Wireless monitoring, visualization and control with real-time feedback during the experiment is shown. Firstly, the wireless setup is used for monitoring and controlling of in-situ temperature and moisture in an environmental chamber of a nanoindenter. The parameters are essential for proper coupling with mechanical results gained by the nanoindenter on cement samples. Secondly, pressure measurements in construction site conditions are remotely acquired on a wall cast from self-compacting concrete. Third, system feedback control is shown on an example of hydration heat monitoring. Temperature is remotely monitored during the experiment. Thermal damage to the cement sample is avoided by the system’s automated cooling.

We report results from a study on the influence of the substitution of Zn2+ cations in the Y-type Ba0.5Sr1.5Zn2Fe12O22 hexaferrite, known for strong magnetoelectric coupling, with magnetic cations, such as Ni2+, on its structural and magnetic properties. Polycrystalline samples of Ba0.5Sr1.5ZnNiFe12O22 were synthesized by citric acid sol-gel auto-combustion. The saturation magnetization value of 54.7 emu/g at 4.2 K was reduced to 37.2 emu/g at 300 K. The temperature dependence of the magnetization at magnetic fields of 50 Oe, 100 Oe and 500 Oe were used to determine the magnetic phase transition temperature. We demonstrate that the helical spin state, believed to cause the magnetoelectric effect, can be achieved by varying the magnetic field strength within a given temperature range.

In this study, the results of the thermomechanical simulation of the process of the multi-stage plastic shaping of the 30CrMoV1211 tool steel with the application of the forging method in the form of the distributions of local values of the strain state, the stress state, temperature, and also the damage factor making it possible to predict a crack in a material in the course of plastic deformation, are presented. A numerical analysis was conducted with the application of the pre-developed spatial mathematical model upon the basis of the finite element method, and with the application of a professional program, DEFORM-3D. The analysis of the constituents of the strain state and the stress state, and also their changes in the course of completing the particular stages of deformation, made it possible to determine the areas of the largest plastic deformations and the places of the hypothetical cracks in a material, which provided the possibility of the preliminary predicting of the internal quality of a forging at the subsequent stages of forging with the increasing forging ratio. The results of numerical research were subjected to experimental verification.

Due to their high strength and stiffness at comparatively low weight, lightweight construction materials such as fiber reinforced plastics (FRP) are used in a variety of technical systems. The areas of application range from aerospace and renewable energies to the automotive sector, which is gaining increasing importance. The non-destructive testing (NDT) by means of air-coupled ultrasound is a decisive factor for the detection of production and operation induced defects. As a result, it is possible to examine components regarding possible defects without contact or coupling medium. By using carbon fiber reinforced plastic (CFRP) pipes with different geometries, it was possible to demonstrate the suitability of air-coupled ultrasound for defect detection. For this purpose, guided waves were contactlessly excited in the pipe, which circumferentially propagated along the components’ cross-section. Based on the amplitude and phase characteristics of the waves, defects could be detected in different axial and circumferential positions within short inspection times of a few seconds. The developed testing method is automatable and hence offers a high potential for future quality control in serial production.

Inspection of bulk wall loss, due to far side surface corrosion in ferromagnetic steel pipe, is a common requirement across multiple industries, including chemical processing, and oil and gas. In the nuclear industry, there is a requirement for inspection of tile holes and balance of plant inspections, where insulated pipe is present. Inspection is typically done using ultrasonic testing, which necessitates a coupling agent and removal of any insulation. Pulsed eddy current (PEC) technique does not require direct contact and has a larger spot size, thereby facilitating more rapid inspection without insulation removal. To further develop the potential of PEC to inspect under these conditions, a reflection type PEC probe was examined for inspection of thickness of steel plate. PEC data was taken for different plate thicknesses so that sensitivity to wall loss due to corrosion could be assessed. The PEC signal was analyzed by fitting the tail of the transient decay with an exponential curve, with curve fitting parameters correlated to wall thickness variation. An analytical model was developed and partially validated in order to examine a wider range of factors, such as probe dimensions, number of turns, and magnetic permeability and conductivity of the steel. The modelled data was also used to perform a sensitivity analysis on probe dimensions in order to realise the largest range of wall thickness with highest spatial resolution. A finite element method model of the reflection probe over steel plate was used to provide insights into the observation from the analytical model that outer pickup coil radius was the most significant optimization parameter.

Magnetic materials are produced in large rolls that need to be cut to specific dimensions to make final products. The high residual stresses, sheet deformation and burr formation at cut surface during the cutting process leads to deterioration of magnetic properties of this materials. The paper focuses on the numerical and experimental analysis of guillotining process using FEM. In computer models dynamic effects, mechanical coupling, constitutive damage law and contact friction are taken into account. The effect of main process parameters on force characteristics, sheet deformation and burr formation on cut surface of grain oriented silicone steel is analyzed. The results of computer simulations can be used to forecasting quality of the final product.

Differences in the construction, material and shape of guitars affect the sound produced, which is related to how the structure vibrates. In this paper, we present a vibration simulation of classical guitar top plates made from spruce and petung bamboo at subsequent stages of production: (i) guitar top plate without sound hole, (ii) guitar top plate with sound hole without bracings, (iii) guitar top plate with sound hole and bracings, and (iv) guitar top plate attached to the body. The change of natural frequencies and mode shapes from one stage to another are presented, as well as the effect of using different top plate materials and bracings. The spruce top plate was found to have lower natural frequencies compared to the petung bamboo guitar at every production stage. The addition of the sound hole does not significantly affect the natural frequencies and mode shapes of both guitar top plates. The addition of bracings, however, significantly alters the natural frequencies and mode shapes of the top plates by introducing more natural frequencies. Top plates with X-bracings tend to have higher frequencies than those with fan bracings. The attachment of the top plate to the guitar body, not yet including the air coupling within the cavity, increases the natural frequencies of the system. These results will be further validated by experimental modal analysis of the guitar top plates.

Glass Fiber Reinforced Polymer (GFRP) was commonly used as outer layer, and it may expose to the ultraviolet exposure and prone to UV radiation. UV radiation will lead to degradation of the GFRP itself and it will reduce the quality and function of GFRP. This paper is a review of past studies on UV Radiation of Glass Fiber Reinforced Polymer (GFRP) in transmission line tower. A study on UV radiation toward coupling steel laminates of GFRP pultruded show the load carry the capacity of the joint was found to be increase, it was due to polymerization of the adhesives. While, a study of UV radiation on GFRP show during the aging process GFRP show signs of plasticization and after 6 months the tensile strength of GFRP show substantial descending pattern and the tensile modulus were found less affected compared to tensile strength. Glass Fiber Reinforced Polymer (GFRP) has a good potential as a material to resist UV radiation.

We have studied the structural, magnetic and magnetodielectric measurements of polycrystalline Ni0.5Co0.5Cr2O4. The magnetic measurement shows that Curie temperature is 80 K for the spinel ferrimagnet Ni0.5Co0.5Cr2O4. We found another magnetic transition at 33K besides Curie temperature. Magnetodielectric measurements of Ni0.5Co0.5Cr2O4 suggest an anomaly at 45 K. Below Curie temperature (45 K), a strong magnetic field dependence of the dielectric constant is observed with cusp-like curve. The strength of the large magnetodielectric response in this system can be explained by optimal spin-orbit coupling.

The continuous research for lightweight components for transport applications to reduce the harmful emissions drives the attention to the light alloys as in the case of Aluminium (Al) alloys, capable to combine low density with high values of the strength-to-weight ratio. Such advantages are partially counterbalanced by the poor formability at room temperature. A viable solution is to adopt a localized heat treatment by laser of the blank before the forming process to obtain a tailored distribution of material properties so that the blank can be formed at room temperature by means of conventional press machines. Such an approach has been extensively investigated for age hardenable alloys, but in the present work the attention is focused on the 5000 series; in particular, the optimization of the deep drawing process of the alloy AA5754 H32 is proposed through a numerical/experimental approach. A preliminary investigation was necessary to correctly tune the laser parameters (focus length, spot dimension) to effectively obtain the annealed state. Optimal process parameters were then obtained coupling a 2D FE model with an optimization platform managed by a multi-objective genetic algorithm. The optimal solution (i.e. able to maximize the LDR) in terms of blankholder force and extent of the annealed region was thus evaluated and validated through experimental trials. A good matching between experimental and numerical results was found. The optimal solution allowed to obtain an LDR of the locally heat treated blank larger than the one of the material either in the wrought condition (H32) either in the annealed condition (H111).

The chitosan powder was added into recycled low density polyethylene (rLDPE) to form composites with different filler loading. Since the chitosan was not compatible with rLDPE, Ultra Plast TP01 (TP01) was added as coupling agent with the aim to improve the properties of composites. In this study, the rLDPE/chitosan composites were prepared by using Z-blade mixer. The effects of chitosan loading and TP01 on tensile properties of rLDPE/chitosan composites were studied. It was discovered that the tensile strength and modulus of elasticity of composites increased with the rise of chitosan loading. The presence of TP01 had further enhanced the tensile strength and stiffness of rLDPE/chitosan composites in comparison to the composites without coupling agent. However, the addition of chitosan and TP01 had decreased the ductility of composites as the elongation at break of composites was declined. It was believed that TP01 managed to improve the interfacial bonding between chitosan and rLDPE, that resulting in th...

We investigate the effect of alloying on Ti2C MXene to understand their role in manipulating its mechanical properties. We consider substitutional doping of B at C site of Ti2C. We estimate the quantities such as in-plane stiffness, Young’s modulus, and critical strain and establish that B doping is highly effective in improving the elastic properties of Ti2C. Our study further reveals the presence of strong spin-phonon coupling in unpassivated Ti2C compounds which influences its mechanical behavior. The damage of Ti2C in its magnetic ground state of A-type antiferromagnetic structure is found to occur at much higher strain than that of the nonmagnetic Ti2C.

In this study, we have investigated the magnetic and magneto-structural transition in Mn-rich Mn2NiSn off-stoichiometric Heusler alloys by introducing Gd separately in the place of Mn and Ni. The structural transition temperature is found to change significantly due to the addition of Gd. Although Gd carries a very large moment as compared to the transition metal elements, the magnetocaloric properties are found to drop drastically where Mn are replaced by Gd. The reason of such observation is the weakening of antiferro coupling between the inter-site Mn atoms in the martensitic phase, which in turn diminishes the sensitivity of the magneto-structural transition.

Apparent coupling loss factors (CLF) and velocity responses has been computed for two lap joined adhesive bonded plates using finite element and experimental statistical energy analysis like approach. A finite element model of the plates has been created using ANSYS software. The statistical energy parameters have been computed using the velocity responses obtained from a harmonic forced excitation analysis. Experiments have been carried out for two different cases of adhesive bonded joints and the results have been compared with the apparent coupling factors and velocity responses obtained from finite element analysis. The results obtained from the studies signify the importance of modeling of adhesive bonded joints in computation of the apparent coupling factors and its further use in computation of energies and velocity responses using statistical energy analysis like approach.

In order to study the erosion regularities of pipelines with gas-solid flow and to predict the location where the maximum erosion occurs, the Eulerian-Lagrangian method was employed to calculate the gas-solid flow inner the pipeline. The gas phase flow field was calculated under the Eulerian coordinate system and the trajectory of particles were calculated under the Lagrangian coordinate system. The DNV erosion model and Forder et al. particle-wall collision model were used to calculate the erosion rate of the pipe wall. The two-way coupling method was taken into consideration in the process of numerical calculation. Multiple models are combined to study the erosion rate and the maximum erosion location of elbows under the conditions of five parameters which exert the most serious effect on erosion, including pipe diameter, particle diameter, inlet velocity, etc. The results show that: (1) the maximum erosion location of the pipe bend is sensitive with the change of the bend orientation, pipe diameter and...

The structural and the temperature-dependent exchange bias properties of room temperature reactive sputtered Fe3O4 (150 nm) thin films are studied. The structural study shows that the films are polycrystalline with no preferred orientation. The exchange bias measurement performed at various temperatures shows a consistent increase in the magnitude of exchange bias field (HEB) as the temperature is lowered from 300 K, and showing a significant increase at low temperatures, which reaches a value of HEB = 190 Oe at 2 K. The presence of exchange bias effect is mainly due to the existence of a non-negligible exchange coupling between the core spins and the surface spins of Fe3O4 grains.

The distribution of the unconventional reservoir fracture network is influenced by many factors. For the natural fracture undeveloped reservoir, the reservoir heterogeneity, construction factors (fracturing fluid flow rate, fluid viscosity, perforation clusters spacing), horizontal stress difference and stress different coefficient are the main factors that affect the fracture propagation. In the study, first, calculate the reservoir physics mechanics parameters that affect the fracture propagation on the base of the logging date from one actual horizontal well. Set the formation parameters according to the calculation that used to simulate the reservoir heterogeneity. Then, using damage mechanics method, the 2D fracture propagation model with seepage-stress-damage coupling of multi-fracture tight sand reservoir was established. Study the influences of different fracturing ways (open whole fracturing and oriented perforation fracturing) and the position of the perforation clusters to the fracture propagation for heterogeneity reservoir. Analyze the effects of flow rate, fracturing fluid viscosity, perforation clusters spacing, horizontal stress difference and stress different coefficient to fracture morphology for the heterogeneity reservoir and contrast with the homogeneous reservoir. The simulation results show that: the fracture morphology is more complexity formed by oriented perforation crack than open whole crack; For natural fracture undeveloped reservoir, as the flow rate or the fracturing fluid viscosity increases within a certain range, the fracture network tends to be more complexity and the effect is more obvious to heterogeneous reservoir than homogeneous reservoir; As the perforation clusters spacing decreases, the interaction of each fracture will increase, it tends to form more complexity fracture network but with short major fracture; If the horizontal stress difference and stress different coefficient is large (The stress different coefficient >0.25), it tends to form planar main fracture, and the capacity of forming fracture network is weak.

Synthesis of Nd–doped BFO multiferroic nanoceramic by the conventional sol-gel method has been carried out. HRXRD and FESEM have been used for the structural analysis to confirm the triclinic structure and to obtain the surface morphology showing agglomeration and to find out the size of the nanoparticles. A high precision LCR meter has been used to record the dielectric constants at various temperatures. Several anomalies are observed whose physical explanations have been given. Space charge polarization effect and magnetoelectric coupling have been confirmed in the synthesized Bi0.9Nd0.1FeO3 nanoceramic sample.

Hot forging is a process used to form difficult to form materials as well as to achieve complex geometries. This is possible due to the reduction of yield stress at high temperatures and a subsequent increase in formability. Numerical methods have been used to predict the material yield and the stress/strain states of the final product. Pseudo Inverse Approach (PIA) developed in the context of cold forming provides a quick estimate of the stress and strain fields in the final product for a given initial shape. In this paper, PIA is extended to include the thermal effects on the forging process. A Johnson-Cook thermo-viscoplastic material law is considered and a staggered scheme is employed for the coupling between the mechanical and thermal problems. The results are compared with available commercial codes to show the efficiency and the limitations of PIA.

Four novel composite systems having composition “80 wt% BaFe12O19 (BaM)-20 wt% Na0.5Bi0.5TiO3 (NBT)” were prepared by solid state reaction technique with considering the variation of microstructure for both the phases. The formation of desired composite systems was confirmed by X-ray diffraction study. From SEM and FESEM images it was found that both the phases are well connected with each and forming 0-3 type particulate composite. From the magneto-capacitance data it was observed that, the composite system which have larger size (≈ micron range) matrix phase (BaM) and smaller size (≈ nano range) disperse phase has highest extrinsic magneto-capacitance (MC %) effect than others. In this report we were also tried to predict the intrinsic magneto-electric coupling in these four composite systems with the help of magneto-impedance spectroscopy.

A three-dimensional dynamic solidification model incorporating the thermo-elastic-plastic coupling model has been proposed in this paper by ABAQUS considering the dynamic contact between the slab and rolls. The thermo-mechanical coupling model produces outputs such as temperature and mechanical behavior of the slab. And the stress-strain distribution of the high-temperature slab at the solidification end has been investigated in this paper. The influences of various reduction interval, reduction amount and reduction distribution on mechanical behavior of casting slab have been systematically discussed.

This article is an overview of the techniques used today in the area of rheology and flow simulation, on the industrial level, for cast film extrusion die design. This industry has made significant progress over the past three decades and die and feedblock design and optimization certainly have been instrumental in the overall improvement. Dies and coextrusion feedblocks are a critical aspect of the process due to the layering and forming function, which drive the final product economics and properties. Polymer melt rheology is a key aspect to consider when optimizing the flow patterns in the extrusion equipment. Not only is rheology critical for the flow channel design when aiming at obtaining a uniform flow distribution at the die exit, but also it is playing a major role in the thermal aspect of the flow due to the strong mechanical and thermal coupling. This coupling comes, on one hand, from the occurrence of viscous dissipation in the flow and on the other hand from the significant temperature depend...

Ni-Zn substituted M-type barium ferrite nanocomposite has been prepared via citrate precursor method. Nanocomposite having composition BaNi0.5Zn0.5Fe11O19 was sintered at 900°C for 3hrs and characterized by using different characterization techniques. X-ray diffraction (XRD) confirmed the formation of double phase with most prominent peak at (114). Average crystallite size for pure BaM and BNZFO were found to be 36 nm & 45 nm. Field emission scanning electron microscopy (FESEM) confirmed the formation of hexagonal platelets with a layered structure. Magnetic properties of these samples were investigated by using vibrating sample magnetometer (VSM). Magnetic parameters like saturation magnetization (Ms), coericivity (Hc) and squareness ratio (SQR) of nanocomposite were found to be 60 emu/g, 3663 Oe and 0.6163 respectively. These values were noticed to be higher as compared to pure BaM. Enhanced magnetic properties of nanocomposite were strongly dependent on exchange coupling. Therefore these properties make this nanocomposite a suitable candidate for magnetic recording and high frequency applications.

An environmentally friendly composite was fabricated from chitosan and recycled low density polyethylene (rLDPE) with the means of melt mixing at 180 °C. The composites were prepared in different loading (10, 20, 30 and 40 php) of chitosan. Due to the incompatibility between filler and matrix, a coupling agent, Ultraplus TP01, was added into the composites. The melt flow index (MFI) values of rLDPE/chitosan composites decreased with chitosan loading but increased with rise of temperature. With the presence of Ultraplus TP01, MFI values of composites were decreased. The thermal stability of rLDPE/chitosan was reduced with increase of chitosan loading but increased with addition of Ultraplus TP01. It was believed that Ultraplus TP01 had provided better interfacial bonding between chitosan and rLDPE, thus enhanced the thermal stability of rLDPE/chitosan composites.

Based on fiber reinforced continuum mechanics theory, an anisotropic hyperelastic constitutive model with biaxial tension coupling for woven composite reinforcements is developed. Experimental data from literature are used to identify material parameters in the constitutive model for a specific balanced plain woven fabric. The developed model is validated by comparing numerical results with experimental biaxial tension data under different stretch ratios and picture-frame shear data, demonstrating that the developed constitutive model is highly suitable to characterize the highly non-linear and strongly anisotropic mechanical behaviors of woven composite reinforcements under large deformation.

Evaporation of water from a ceramic layer is a key phenomenon in the drying process for the manufacturing of tape cast ceramics. This process contains mass, momentum and energy exchange between the porous medium and the free-flow region. In order to analyze such interaction processes, a Representative Elementary Volume (REV)-scale model concept is presented for coupling non-isothermal multi-phase compositional porous-media flow and single-phase compositional laminar free-flow. The preliminary results show the typical expected evaporation behaviour from a porous medium initially saturated with water, and its transport to the free-flow region according to the existent results from the literature.

A model of initiation of the reaction in the flat layer under external heating and various loading was proposed and numerically investigated. Different types of mechanical loading such as uniaxial loading, compression and pure shear were considered. The estimation of stressed-deformed state of reaction system with consumable component and reaction product is based on the model of Maxwell’s viscoelastic body. The influence of the coupling between thermal and mechanical processes on temperature, stress and strain fields was investigated. The phenomenon of thermal explosion caused by the acceleration of the reaction by additional thermal flux due to viscous dissipation was discovered.

This communication is devoted to the presentation of our recent results regarding the asymptotic analysis of a viscous flow in a tube with elastic walls. This study can be applied, for example, to the blood flow in an artery. With this aim, we consider the dynamic problem of the incompressible flow of a viscous fluid through a curved pipe with a smooth central curve. Our analysis leads to the obtention of an one dimensional model via singular perturbation of the Navier-Stokes system as e, a non dimensional parameter related to the radius of cross-section of the tube, tends to zero. We allow the radius depend on tangential direction and time, so a coupling with an elastic or viscoelastic law on the wall of the pipe is possible.To perform the asymptotic analysis, we do a change of variable to a reference domain where we assume the existence of asymptotic expansions on e for both velocity and pressure which, upon substitution on Navier-Stokes equations, leads to the characterization of various terms of the e...

Coda waves are the late arriving portion of bulk or guided waves, and are the result of scattering of the waves due to heterogeneities in the material. Since these waves interact with a region multiple times, the effect of otherwise undetectable changes in material and/or stress state accumulates and becomes detectable. This work examines the feasibility of detecting incipient fatigue damage in CFRP sample with coda wave analysis. Specimens are subjected to low cycle fatigue in a four-point bend set-up. Ultrasonic measurements are periodically taken perpendicular to the direction of loading during the fatiguing process after removing all loads. Detection and reception sensitivity of coda waves in composites are studied. Also studied are the effects of the coupling between the transducer and sample for a reliable and repeatable measurement.

Based on discrete element method, the authors model loading of a physical specimen to describe its capacity to accumulate and release elastic energy. The specimen is modeled as a packing of particles with viscoelastic coupling and friction. The external elastic boundary of the packing is represented by particles connected by elastic springs. The latter means introduction of an additional special potential of interaction between the boundary particles, that exercises effect even when there is no direct contact between the particles. On the whole, the model specimen represents an element of a medium capable of accumulation of deformation energy in the form of internal stresses. The data of the numerical modeling of the physical specimen compression and the laboratory testing results show good qualitative consistency.

In this work we have predicted the mechanical and magnetic properties of cubic austenite phase of the Cu substituted alloys of Ni2MnGa and Mn2NiGa at the Ga site i.e. Ni2MnCu and Mn2NiCu, respectively, as well as of Pt2MnCu and Pd2MnCu. We have observed that the conventional Heusler structure is lower in energy compared to the inverse Heusler structure for the Ni2MnGa, Pt2MnGa and Pd2MnGa and the Cu-substituted materials, whereas Mn2NiGa and its Cu-substituted alloy at Ga site assume the inverse structure. From the calculated elastic constants, we find that Pt2MnCu is expected to be the most ductile material among all the substituted materials studied here. We have calculated and compared the Curie temperatures derived from the Heisenberg exchange coupling parameters.

In this work, the production and mechanical characterization of density graded biocomposites based on high density polyethylene and hemp fibres was performed. The effect of coupling agent addition (maleated polyethylene) and hemp content (0-30%) was studied to determine the effect of hemp distribution (graded content) inside the composite (uniform, linear, V and Λ). Tensile and flexural properties are reported to compare the structures, especially in terms of their stress-strain behaviors under tensile loading.

Ultrasonic inspection of wall thickness in pipes is a standard technique applied widely in the petrochemical industry. The potential precision of repeat measurements with permanently installed ultrasonic sensors however significantly surpasses that of handheld sensors as uncertainties associated with coupling fluids and positional offsets are eliminated. With permanently installed sensors the precise evaluation of very small wall loss rates becomes feasible in a matter of hours. The improved accuracy and speed of wall loss rate measurements can be used to evaluate and develop more effective mitigation strategies. This paper presents an overview of factors causing variability in the ultrasonic measurements which are then systematically addressed and an experimental setup with the best achievable stability based on these considerations is presented. In the experimental setup galvanic corrosion is used to induce predictable and very small wall thickness loss. Furthermore, it is shown that the experimental measurements can be used to assess the effect of reduced wall loss that is produced by the injection of corrosion inhibitor. The measurements show an estimated standard deviation of about 20nm, which in turn allows us to evaluate the effect and behaviour of corrosion inhibitors within less than an hour.

Conventional and commercially available inline wall thickness monitoring systems for pipe extrusion are usually based on ultrasonic or x-ray technology. Disadvantages of ultrasonic systems are the usual need of water as a coupling media and the high damping in thick walled or foamed pipes. For x-ray systems special safety requirements have to be taken into account because of the ionizing radiation. The terahertz (THz) technology offers a novel approach to solve these problems. THz waves have many properties which are suitable for the non-destructive testing of plastics. The absorption of electrical isolators is typically very low and the radiation is non-ionizing in comparison to x-rays. Through the electromagnetic origin of the THz waves they can be used for contact free measurements. Foams show a much lower absorption in contrast to acoustic waves. The developed system uses THz pulses which are generated by stimulating photoconductive switches with femtosecond laser pulses. The time of flight of THz pul...

The magnetic field effect (MFE) on liquidus boundary of Bi-Mn binary system was investigated by differential thermal analysis (DTA) and the computer coupling of phase diagram method (CALPHAD). The liquidus boundary for Bi-18at.%Mn and Bi-24at.%Mn rose clearly by the application of the magnetic fields. The MFE for liquidus boundary temperature Tliq changed from ΔTliq∝B2 to ΔTliq∝B because of the large increase of the peritectic temperature from BiMn and BiMn1.08 by the application of magnetic field.

Thermosonics or SonicIR has been proven an effective NDT method, in which ultrasonic welding horn is pushed against the tested sample under certain force through a piece of coupling material. Due to the mechanical contact between horn and sample, it may damage the contacted surface, especially for some brittle or fragile samples. In this study, the conventional horn in a small size was replaced by a much bigger horn to avoid the direct contact of horn with the sample. The tested sample could be positioned up to several centimeters away from the bottom or beside of the horn, heat is generated at the defect location under the excitation of ultrasonic field, its heating mechanism is similar with contact thermosonics, the infrared camera could be positioned wherever is convenient to monitor the variation of the surface temperature. The presented experimental results show that the non-contact thermosonics has some potential in NDT application.

Mold filling processes of refrigerators, car dashboards or steering wheels are some of the many application areas of polyurethane foams. The design of these processes still mainly relies on empirical approaches. Therefore, we first developed a modeling approach describing mold filling processes in complex geometries. Hence, it is possible to study macroscopic foam flow and to identify voids. The final properties of polyurethane foams may vary significantly depending on the location within a product. Additionally, the local foam structure influences foam properties like thermal conductivity or impact strength significantly. It is neither possible nor would it be efficient to model complex geometries completely on bubble scale. For this reason, we developed a modeling approach describing the bubble growth and the evolution of the foam structure for a limited number of bubbles in a representative volume. Finally, we coupled our two simulation approaches by introducing tracer particles into our mold filling simulations. Through this coupling, a basis for studying the evolution of the local foam structure in complex geometries is provided.

In this study, the propagation of guided waves in a 0.9m Aluminium Conductor Steel Reinforced (ACSR) cable was investigated employing two longitudinal piezoelectric transducers attached to the ends of the cable. Longitudinal L(0,1) and flexural F(1,1) modes were identified at 500 kHz via dispersion curves and the wavelet transform. Based on inter-wire coupling, a 3-D FEM analysis was performed using a simplified model comprised of two rods made of aluminium and steel. Artificial damage was made by gradually increasing cut depth, in the middle of the cable, from 1mm to 9mm. The attained experimental results suggest a mode conversion from F(1,1) to L(0,1) due to loosed friction contact among individual wires corroborating the results yielded by the FEM analysis.

Recently, electro-plastic forming to be a focus of attention in materials hot processing research area, because it is a sort of energy-saving, high efficient and green manufacturing technology. An electro-thermo-mechanical model can be adopted to carry out the sequence simulation of aluminum matrix composites sheet deep drawing via electro-thermal coupling and thermal-mechanical coupling method. The first step of process is resistance heating of sheet, then turn off the power, and the second step is deep drawing. Temperature distribution of SiCp/2024Al composite sheet by resistance heating and sheet deep drawing deformation were analyzed. During the simulation, effect of contact resistances, temperature coefficient of resistance for electrode material and SiCp/2024Al composite on temperature distribution were integrally considered. The simulation results demonstrate that Sicp/2024Al composite sheet can be rapidly heated to 400° in 30s using resistances heating and the sheet temperature can be controlled by adjusting the current density. Physical properties of the electrode materials can significantly affect the composite sheet temperature distribution. The temperature difference between the center and the side of the sheet is proportional to the thermal conductivity of the electrode, the principal cause of which is that the heat transfers from the sheet to the electrode. SiCp/2024Al thin-wall part can be intactly manufactured at strain rate of 0.08s−1 and the sheet thickness thinning rate is limited within 20%, which corresponds well to the experimental result.

Utilization of a spray-on deposition technique of ferroelectric bismuth titanate (Bi4Ti3O12) composites has a competitive advantage to standard ultrasonic transducers. These can conform to curved surfaces, can operate at high temperature (Curie-Weiss temperature 685 °C) and are mechanically well-coupled to a substrate. However, an issue with many high temperature transducers such as bismuth titanate ceramics is that they have relatively low transduction efficiency, i.e. d33 is about 12-14 pC/F in Bi4Ti3O12 versus 650 pC/F in PZT-5H. It is a common conception that high-temperature capability comes at the cost of electro-mechanical coupling. It will be shown that the high temperature capability of bismuth-titanate-PZT composite transducers using the spray-on deposition technique previously developed, improves the electro-mechanical coupling while maintaining the high temperature performance and mechanical coupling. This material could provide advantages in harsh environments where high signal-to-noise ratios are needed.

Structural property of Mechanical milled sample show structural order-disorder phase transition from L21 to B2 structure. Variation of magnetic properties with milling time obtained from dc magnetization show systematic trend on prolong milling Mn-site disorder form anti-parallel coupling which further reduces magnetic moment. However the transition temperature remains independent of milling time and presence of a small hump in HT-MT curve is a signature of antiferromagnetic coupling.

Hot-roller warm rolling process is expected to achieve a breakthrough in solving the problem of high quality rolling for difficult deformed metals. In this paper roll surface induction heating was studied based on the finite element theory of electromagnetic-thermal coupling and experiment. The law of temperature field for a static roll in induction heating process was analyzed by FEM. The results show that roll surface temperature can achieve 721°C at 48s under 20000Hz power frequency, 350×104A/m2 current density, due to the skin effect on roll surface. Using a special induction coil in the laboratory, an experiment of roll induction heating was carried out with the same process parameters. The calculated results of temperature on roll surface agree well with the measured value.

Laser driven flyers are produced on the interaction of a laser pulse with a thin film of metal. When an Nd:YAG laser is focussed through a transparent substrate onto a 5 micron film of aluminium, a fraction of the metal is ablated. The associated expansion causes the remaining aluminium to be punched from the film and launched as a discrete flyer. Due to the high reflectivity of aluminium, some of the laser energy is lost through reflection at the substrate/metal boundary. By introducing metals which exhibit stronger absorption at the Nd:YAG wavelength (1.064 μm), the laser coupling to the flyer should be improved, resulting in faster flyer velocities for a given pulse energy. This paper discusses the results of using Hf, Ge, Zn and Ti to improve the coupling of the Nd:YAG laser to the flyer.

Environmental ageing in composites is a very important issue for the effect induced on material properties. The most common effect is induced by absorption of low molecular weight substances (water or organic solvents), usually controlled by diffusion mechanisms. Some cases of use of hybrid materials, coupling low diffusion plies with "conventional" ones are discussed and potential improvement of composites for structural applications based on such concept is envisaged. Specifically, metal hybrid composites (GLARE), multilayer amorphous-semicrystalline materials and composites modified with layer of nanocharges or nano-reinforcements are considered, and the absorption kinetics are evaluated by a numerical model.

Ion-track membranes (ITM) are known as polymer films with straight pore channels the size, shape, orientation and density of which can be precisely controlled. Previous ultrasonic studies of ITM using air-coupled and wide-band ultrasound pulses (0.1-5.0 MHz) revealed the possibility to isolate and study ultrasound propagation in these pores. Hence a novel ultrasonic technique has been established to determine pore characteristics of ITM using this pore propagation mode. In this work, we present a modification of the technique based on the use of pressurized air. This is achieved by enclosing transducers and samples in a pressurized chamber (1-9 bar). The main objective of this study is to reduce the attenuation of the ultrasound waves propagating in the pores and to increase the coupling of the ultrasonic energy into this pore propagation mode at the membrane surface in order to extend the applicability range of the existing technique to the characterization of ITM with small pores (diameter < 200 nm), or with very low porosity (

A numerical simulation of shock experiments on Cerium is reported in the present, by using a multiphase equation of state (MEOS) , a multiphase Steinberg-Guinan (MSG) constitutive model and non-equilibrium phase transition process for Cerium. A volume change of about 15% occurs when Cerium is subject to high pressure (~0.7 GPa) and γ→α phase change takes place. The phase transition and constitutive model are coupling and it is hard to distinguish by single experiment. The passive confined pressure SHPB test method can give the pressure-volume under dynamic loading and release including the phase transition character of Cerium. The free surface/window velocity which coupling the information of phase transition and constitutive model can also be given by the plane impact experiment. This is an attempt by two kinds of experiment to obtaining a multiphase equation of state, constitutive model and non-equilibrium phase transition equation.

A recent technology has been introduced into the paper industry that makes possible to produce paper materials by replacing the cellulose fibres by a mineral powder, achieving a more environmentally friendly product compared with conventional paper. The purpose of this work is to determine the possibilities of an air-coupled ultrasonic technique to study this kind of new materials in order to develop an ultrasonic system useful for quality control for this industry. In particular, air-coupled ultrasonic spectroscopy is specially well suited to this kind of materials because of the fact that no coupling liquid and no direct contact with the sample is employed. A through transmission technique is employed and Fourier analysis is performed to obtain both magnitude and phase spectra of the transmission coefficient. Properties in the thickness direction as well as in the paper plane are investigated. Different paper grades (from 120 to 400 g/m2) provided by Terraskin have been studied. Very high attenuation coeficientes and very low propagation velocities (and hence elastic constant) are obtained, this can be explained by considering the large porosity of this material (about 50%) and the microstrucutre: solid grains in contact with a variable amount of polymeric resin partially filling the pore space.

Modelling the forming process of engineering fabrics and textile composites using a mechanical approach, such as FEM, requires characterisation of material behaviour. Using Picture Frame (PF) tests, several previous studies have reported a coupling between in‐plane tension and fabric shear compliance. However, characterising this behaviour accurately has proven problematic due to the sensitivity of the PF test to small fabric misalignments in the test rig, prompting innovative solutions such as the use of load‐cells mounted on the side bars of the PF rig to measure in‐plane tension during testing. This paper focuses on an alternative testing technique, the Biaxial Bias Extension test, as a means to investigate this coupling. The approach has several benefits including simple equipment requirements, the ability to vary sample dimensions and boundary conditions. The main difficulty lies in extracting the material contribution to the recorded signal. To do this, an experimental method is demonstrated using two very different textiles; glass fabric and self‐reinforced polypropylene both plain weaves. The latter is challenging to characterise and was chosen due to its high propensity to wrinkle at room temperature.

Hot‐dipping galvanizing process is a widely used and efficient way to protect steel from corrosion. We propose to master the microstructure of zinc grains by investigating the relevant process parameters. In order to improve the texture of this coating, we model grain nucleation and growth processes and simulate the zinc solid phase development.A coupling scheme model has been applied with this aim. This model improves a previous two‐dimensional model of the solidification process. It couples a cellular automaton (CA) approach and a finite element (FE) method. CA grid and FE mesh are superimposed on the same domain. The grain development is simulated at the micro‐scale based on the CA grid. A nucleation law is defined using a Gaussian probability and a random set of nucleating cells. A crystallographic orientation is defined for each one with a choice of Euler’s angle (Ψ,θ,φ). A small growing shape is then associated to each cell in the mushy domain and a dendrite tip kinetics is defined using the model o...