Microscopic level modeling of induction welding heating mechanisms in thermoplastic composites

2021 ◽  
pp. 089270572110466
Author(s):  
Darun Barazanchy ◽  
Michel van Tooren ◽  
Mohammod Ali
Keyword(s):  
Cross Section ◽  
Carbon Fibers ◽  
Volume Fraction ◽  
Circular Cross Section ◽  
Microscopic Level ◽  
Thermoplastic Composites ◽  
Heating Process ◽  
Fiber Volume ◽  
Electrical Fields ◽  
Solid Loss

Simulation and analysis of electromagnetic induction heating of continuous conductive fiber-based composite materials is used to (in)validate a series of hypotheses on the physics dominating the heating process. The behavior of carbon fibers with and without surrounding polymer in an alternating electromagnetic field is studied at a microscopic level in ANSYS Maxwell using the solid loss to quantify heat generation in the composite material. To limit the number of elements, the fibers are modeled with a polyhedron cross-section instead of a circular cross-section. In addition, each layer is modeled as an layer of fibers, e.g. 20 fibers placed next to each other. The simulations indicate that samples with fibers oriented in 0 and 90 orientation yield a substantial higher solid loss than fibers oriented in the 0 orientation only. The solid loss in both cases is however not enough to explain the level of heating observed in practice. Filling the volumes between fibers with polymer results in greater solid loss than samples with no polymer between the fibers, at equal fiber volume fraction. Note, no contact between fibers is modeled. The conductivity of the polymer is experimentally determined. The lab tests show relatively low finite resistance values in the transverse direction, indicating that the polymer in a composite should not be considered an isolator. The simulations seem to justify the conclusion that heating of thermoplastic composites in an alternating magnetic field rely on currents through the polymer. Without the polymer and subsequently no polymer conductivity, even if the electrical fields are strong there is almost no heat generated. The carbon fibers are required to be in proximity of each other to create the electrical fields that induce the current through the polymer. The heating is determined by the product of current density squared times the resistivity of the polymer.

Modelling of Laser Welding Process on Thermoplastic Composites

2015 ◽  
Vol 651-653 ◽  
pp. 1513-1518 ◽  
Author(s):  
Benoit Cosson
Keyword(s):  
Laser Welding ◽  
Carbon Fibers ◽  
Fiber Volume Fraction ◽  
Volume Fraction ◽  
Laser Energy ◽  
Welding Process ◽  
Thermoplastic Composites ◽  
Homogeneous Material ◽  
Fiber Volume ◽  
Structural Applications

Thermoplastics composites for structural applications are under growing development from the aerospace (carbon fibers with PEI, PPS or PEEK matrices mainly) to the automotive industry (glass and carbon fibers with PP, PA). The plastic deformation they can provide and the assembly facilities through welding techniques are well appreciated. Among the available welding technics, laser offers the possibility to assemble materials in a precise and localized manner and can be easily automated. However, due to the presence of continuous fibers at a high fiber volume fraction, propagation of the laser energy through the composite that present local variation of fiber volume fraction is not as straight forward as in a homogeneous material. Modelling of the laser welding of a thermoplastic/continuous glass fiber is considered here. The study takes into account the microstructure of the composite in order to evaluate changes in local energy absorption and diffusion directly linked with the thickness. Modelling of the welding process is developed from the representation of the moving laser beam. The beam propagation through the composite thickness is considered thanks to the ray tracing method. The proposed method is able to optimise the welding process in function of the microstructure and the material properties of the welded parts.

scholarly journals The investigation of the cavitation processes in the radial labyrinth pump

2018 ◽  
Vol 8 (1) ◽  
pp. 322-328
Author(s):  
Moloshnyi Oleksandr ◽  
Szulc Przemyslaw
Keyword(s):  
Numerical Simulation ◽  
Cross Section ◽  
Volume Fraction ◽  
Mechanical Energy ◽  
Circular Cross Section ◽  
Back Side ◽  
Numerical Investigations ◽  
Numerical Research ◽  
The Moment ◽  
Velocity Pressure

Abstract The paper concerns the analysis of the cavitation processes in the flow passages of the radial labyrinth pump. The object of the analysis contains the active (moving) and the passive (stationary) discs with straight channels trajectory and semi-circular cross-section. The conversion of the mechanical energy into hydraulic based on the exchange of the momentum between the liquid remaining in the moving and the stationary areas of the discs as well as on the centrifugal increase of the moment of momentum. The analysis of the cavitation processes was realized by the experimental research and the numerical simulation. In the article, the comparison of the cavitation characteristics was carried out. The numerical simulation had given similar results to the experimental one, the process of the cavitation was visualized. Furthermore, numerical investigations helped to describe the cavitation development. The results of the numerical research such as the distributions of the velocity, pressure and vapor volume fraction in the passages were presented. At first, cavitation starts on the back side and on the top of the wall between channels of the active disc. Further, the cavitation areas are growing along the axis of the channels. Eventually, they separation was observed and vortices of the vapour-gas mixture in the middle of the channels were formed. This phenomenon is so-called super cavitation vortices.

scholarly journals Characterization of Fiber Alignment and Fiber Volume Content of Long-fiber Reinforced Composites

1994 ◽  
Vol 3 (1) ◽  
pp. 096369359400300
Author(s):  
J. Schuster ◽  
R. Selzer ◽  
K. Friedrich
Keyword(s):  
Volume Fraction ◽  
Processing System ◽  
Thermoplastic Composites ◽  
Scanning Electron Micrographs ◽  
Orientation Factor ◽  
Fiber Reinforced ◽  
Fiber Volume ◽  
Cross Section Area ◽  
Section Area ◽  
Alignment Process

Scanning electron micrographs of long fiber reinforced thermoplastic composites were analyzed using an image processing system. The main objective of this study was to determine the alignment process which takes place during thermoforming of Long Discontinouos Fiber Composties (LDF™). The planar orientation factor and the standard deviation of the fiber cross section area were determined. Thus, an alignment process could be stated. In addition, the fiber volume fraction was calculated.

Uniaxial and Triaxial Stress-Strain Behaviour of Ductile Cement Pastes Reinforced With Wollastonite Microfibers

2013 ◽  
Author(s):  
Fabrício de C. Vitorino ◽  
Romildo D. Toledo Filho
Keyword(s):  
Compressive Strength ◽  
Volume Fraction ◽  
Steam Injection ◽  
Triaxial Tests ◽  
Heating Process ◽  
Oil Well ◽  
Fiber Volume ◽  
Stress Strain ◽  
Cement Pastes ◽  
Cement Sheath

When an oil well is submitted to cyclic steam injection the heating process induces tensile stresses in the cement sheath due to the thermal gradient that take place leading to cement-steel debonding and/or cement cracking. Similar problem can occur if the cement sheath is submitted to high creep deformations coming from the adjacent rock (this is the case for example of oil exploration in salt domes). In both cases sheath cracking can result in loss of hydraulic isolation and consequently in excessive water production with undesired economic and environmental consequences. In order to deal with this challenging scenario oil well cementing systems of special properties (e.g. high tensile strength, low elastic modulus and elevated toughness) should be used as an alternative to conventional high compressive strength systems. In this study cement pastes of high ductility were developed using wollastonite micro-fibers as reinforcement. The mixtures were developed within the framework of the Compressive Packing Model [1] and wollastonite microfibers were added in volume fractions of 2.5, 5.0 and 7.5 %. Uniaxial and triaxial compressive tests were carried out to obtain the unconfined and confined stress-strain behavior of the composites. The crack initiation stress and strain and the fracture process of the pastes under unconfined stress will be reported in this paper. Triaxial tests were performed under confining pressures of 0, 600 and 1200 psi and the Mohr-Coulomb criteria assumed to determine the internal frictional angle and cohesion. The results show that the addition of wollastonite microfibers increased the compressive strength of the pastes keeping the same strain capacity of the matrix. The internal frictional angle was also increased with the increase in the fiber volume fraction. However, the cohesion of the paste was reduced with the fiber addition.

scholarly journals An integral equation method for the homogenization of unidirectional fibre-reinforced media; antiplane elasticity and other potential problems

2017 ◽  
Vol 473 (2201) ◽  
pp. 20170080 ◽  
Author(s):  
Duncan Joyce ◽  
William J. Parnell ◽  
Raphaël C. Assier ◽  
I. David Abrahams
Keyword(s):  
Cross Section ◽  
Volume Fraction ◽  
Effective Properties ◽  
Circular Cross Section ◽  
Rational Functions ◽  
High Volume ◽  
Cross Sectional ◽  
Antiplane Elasticity ◽  
Unidirectional Fibre ◽  
Explicit Expressions

In Parnell & Abrahams (2008 Proc. R. Soc. A 464 , 1461–1482. ( doi:10.1098/rspa.2007.0254 )), a homogenization scheme was developed that gave rise to explicit forms for the effective antiplane shear moduli of a periodic unidirectional fibre-reinforced medium where fibres have non-circular cross section. The explicit expressions are rational functions in the volume fraction. In that scheme, a (non-dilute) approximation was invoked to determine leading-order expressions. Agreement with existing methods was shown to be good except at very high volume fractions. Here, the theory is extended in order to determine higher-order terms in the expansion. Explicit expressions for effective properties can be derived for fibres with non-circular cross section, without recourse to numerical methods. Terms appearing in the expressions are identified as being associated with the lattice geometry of the periodic fibre distribution, fibre cross-sectional shape and host/fibre material properties. Results are derived in the context of antiplane elasticity but the analogy with the potential problem illustrates the broad applicability of the method to, e.g. thermal, electrostatic and magnetostatic problems. The efficacy of the scheme is illustrated by comparison with the well-established method of asymptotic homogenization where for fibres of general cross section, the associated cell problem must be solved by some computational scheme.

Numerical Investigation of Turbulent Magnetic Nanofluid Flow inside Straight Channels

2016 ◽  
Vol 819 ◽  
pp. 382-391 ◽  
Author(s):  
Nor Azwadi Che Sidik ◽  
Mohammed Raad Abdulwahab
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Cross Section ◽  
Volume Fraction ◽  
Numerical Study ◽  
Circular Cross Section ◽  
Average Diameter ◽  
Turbulent Regime ◽  
Reynolds Number Increase ◽  
Number Increase

A numerical study using computational fluid dynamics method with an approach of single phase has been presented in order to determine the effects of the concentration of the nanoparticles and flow rate on the convective heat transfer and friction factor in turbulent regime flowing through three different straight channels (straight, circular and triangular) with different Reynolds number (5000 ≤ Re ≤ 20000) using constant applied heat flux. The nanofluid was used consist of Fe3O4 magnetic nanoparticles with average diameter of (13nm) dispersed in water with four volume fraction (0, 0.2, 0.4, 0.6%). The results revealed that as volume fraction and Reynolds number increase Nusselt number increase and the heat transfer rate in circular cross section tube is better than that in square and triangular cross section channels.

scholarly journals Efficiently, accurately, intelligently dissecting bamboo: characteristic of vascular bundle in Phyllostachys

2021 ◽  
Author(s):  
Haocheng Xu ◽  
Ying Zhang ◽  
Jiajun Wang ◽  
Tuhua Zhong ◽  
Xinxin Ma ◽  
...  
Keyword(s):  
Cross Section ◽  
Radial Distribution ◽  
Vascular Bundle ◽  
Fiber Volume Fraction ◽  
Volume Fraction ◽  
Width Ratio ◽  
Vascular Bundles ◽  
Fiber Volume ◽  
Detection Model ◽  
Gradient Change

AbstractA comprehensive understanding of vascular bundles is the key to elucidate the excellent intrinsic mechanical properties of bamboo. This research aims to investigate the gradient distribution of fiber volume fraction and the gradient changes in the shape of vascular bundles along the radial axis in Phyllostachys. We constructed a universal transfer-learning-based vascular bundle detection model with high precision of up to 96.97%, which can help to acquire the characteristics of vascular bundles quickly and accurately. The total number of vascular bundles, total fiber sheath area, the length, width and area of fiber sheath of individual vascular bundles within the entire cross-section were counted, and the results showed that these parameters had a strongly positive linear correlation with the outer circumference and wall thickness of bamboo culms, but the fiber volume fraction (around 25.5 %) and the length-to-width ratio of the vascular bundles (around 1.226) were relatively constant. Furthermore, we layered the cross section of bamboo according to the wall thickness finely and counted the characteristics of vascular bundle in each layer. The results showed that the radial distribution of fiber volume fraction decreased exponentially, the radial distribution of the length-to-width ratio of vascular bundle decreased quadratically, the radial distribution of the width of vascular bundle increased linearly. The trends of the gradient change in vascular bundle’s characteristics were found highly consistent among 29 bamboo species in Phyllostachys.One sentence summaryA universal vascular bundle detection model can efficiently dissect vascular bundles in Phyllostachys, and the radial gradient change of vascular bundles in cross-section are found highly consistent.

Correlation of Thermal Conductivities of Unidirectional Fibrous Composites Using Local Fractal Techniques

1991 ◽  
Vol 113 (4) ◽  
pp. 788-796 ◽  
Author(s):  
R. Pitchumani ◽  
S. C. Yao
Keyword(s):  
Cross Section ◽  
Volume Fraction ◽  
Fibrous Composite ◽  
Flow Direction ◽  
Fractal Dimensions ◽  
Unit Cell ◽  
Small Range ◽  
Fiber Volume ◽  
Unit Cells ◽  
Traditional Approaches

The arrangement of fibers strongly influences heat conduction in a composite. Traditional approaches using unit cells to describe the fiber arrangements work well in the case of ordered arrays, but are not useful in the context of disordered arrays, which have been analyzed in the literature by statistical means. This work presents a unified treatment using the tool of local fractal dimensions (although, strictly speaking, a composite cross section may not be an exact fractal) to reduce the geometric complexity of the relative fiber arrangement in the composite. The local fractal dimensions of a fibrous composite cross section are the fractal dimensions that it exhibits over a certain small range of length scales. A generalized unit cell is constructed based on the fiber volume fraction and local fractal dimensions along directions parallel and transverse to the heat flow direction. The thermal model resulting from a simplified analysis of this unit cell is shown to be very effective in predicting the conductivities of composites with both ordered as well as disordered arrangement of fibers. For the case of square packing arrays, the theoretical result of the present analysis is identical to that of Springer and Tsai (1967).

Parametric Generation of Random Distribution of Fibers in Long-Fiber Reinforced Composites and Micromechanical FE Analysis

2010 ◽  
Vol 452-453 ◽  
pp. 117-120
Author(s):  
Zhen Qing Wang ◽  
Xiao Qiang Wang ◽  
Ji Feng Zhang ◽  
Song Zhou
Keyword(s):  
Finite Element ◽  
Cross Section ◽  
Fiber Volume Fraction ◽  
Random Distribution ◽  
Volume Fraction ◽  
Fiber Reinforced ◽  
Fiber Volume ◽  
Parametric Generation ◽  
High Fiber ◽  
Damage Initiation

A method for the parametric generation of the transversal cross-section microstructure model of unidirectional long-fiber reinforced composite (LFRC) is presented in this paper. Meanwhile, both the random distribution of the fibers and high fiber volume fraction are considered in the algorithm. The fiber distribution in the cross-section is generated through random movements of the fibers from their initial regular square arrangement. Furthermore, cohesive zone element is introduced into modeling the interphase between the fiber and the matrix. All these processes are carried out by the secondary development of the finite element codes (ABAQUS) via Python language programming. Based on the model generated, micromechanical finite element analysis (FEA) is performed to predict the damage initiation and subsequent evolution of the composites. The results show that this technique is capable of capturing the random distribution nature of these composites even for high fiber volume fraction. Moreover, the results prove that a good agreement with the experimental results is found.

3D layer-to-layer orthogonal interlock woven composites under monotonic loading: Multiscale modeling

2017 ◽  
Vol 36 (17) ◽  
pp. 1263-1285 ◽  
Author(s):  
M Muthukumar ◽  
J Prasath ◽  
S Sathish ◽  
G Ravikumar ◽  
YM Desai ◽  
...  
Keyword(s):  
Boundary Conditions ◽  
Multiscale Modeling ◽  
Cross Section ◽  
Composite Structure ◽  
Volume Fraction ◽  
Woven Composites ◽  
Woven Composite ◽  
Fiber Volume ◽  
Element Analysis ◽  
Unit Cells

Multiscale modeling of 3D layer-to-layer orthogonal interlock woven composite structure for elastic and strength behavior is presented. Due to the inherent nature of weaving, 3D woven composites can be represented by repetitive unit cells at the meso level. The present study focuses on identifying different types of repetitive unit cells considering both the geometry and the boundary conditions. For a typical 3D layer-to-layer orthogonal interlock woven composite, there are eight types of meso repetitive unit cells taking into account both the geometry and the boundary conditions. Additionally, for a practical situation, fiber volume fraction (Vf) in the impregnated strand is not uniform throughout the cross-section. In other words, Vf would be different for different micro repetitive unit cells. The properties of the macro structure, i.e. the 3D woven composite structure has been determined by applying periodic boundary conditions at micro and meso levels and iso-strain conditions at the macro level using finite element analysis. The continuity between the blocks is provided by merging the nodes in the intersection regions. The effect of different Vf at different locations in the transverse cross-section of the strand on the elastic and the strength properties of 3D layer-to-layer woven composite structure is presented.

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