Modeling Group

@article{vanaei_2096,

title = {A comparative in-process monitoring of temperature profile in fused filament fabrication},

author = {Hamidreza Vanaei and Deligant Michael and Mohammadali Shirinbayani and Raissi Kaddour and Joseph Fitoussi and Sofiane Khelladi and Abbas Tcharkhtchi},

url = {https://doi.org/10.1002/pen.25555},

year  = {2020},

date = {2020-10-01},

journal = {Polymer Engineering And Science},

volume = {61},

number = {1},

pages = {68-76},

abstract = {Fused filament fabrication (FFF), an additive manufacturing technique, is used to produce prototypes and a gradually more important processing route to get final products. Due to the layer-by-layer deposition mechanism involved, bonding between adjacent layers is controlled by the thermal energy of the material being printed. Thus, it is strongly in conjunction with the temperature development of the filaments during the deposition sequence. This study gives out an in-process set-up enabling to record temperature profile of two adjacent filaments or a sequence of deposition in various locations during FFF process. The main characteristic of the presented procedure is the possibility of obtaining a global temperature profile resulted from an IR-camera; parallel to those recorded using a K-type thermocouple. Needless to say that a K-type thermocouple accurately records the local temperature at the interface of adjacent filaments. Conversely, an IR-camera signifies the temperature profile on the captured surface. The obtained results showed that there is a remarkable difference between the cooling rate and re-heating peaks. The primary outcome of this study is the consideration of results accuracy and the possibility of working on optimization of the obtained temperature profile. Altogether it helps optimize inter-layer strength while assessing the temperature evolution.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{zhang_1270,

title = {Enhanced CDM model accounting of stress triaxiality and Lode angle for ductile damage prediction in metal forming},

author = {Kai Zhang and Houssem Badreddine and Naila Hfaiedh and Khemais Saanouni and Jianlin Liu},

url = {https://journals.sagepub.com/doi/full/10.1177/1056789520958045},

year  = {2020},

date = {2020-09-01},

journal = {International Journal Of Damage Mechanics},

volume = {30},

number = {2},

pages = {260-282},

abstract = {This paper deals with the prediction of ductile damage based on CDM approach fully coupled with advanced elastoplastic constitutive equations. This fully coupled damage model is developed based on the total energy equivalence assumption under the thermodynamics of irreversible processes framework with state variables. In this model, the damage evolution is enhanced by accounting for both stress triaxiality and Lode angle. The proposed constitutive equations are implemented into Finite Element (FE) code ABAQUS/Explicit through a user material subroutine (VUMAT). The material parameters are determined by the hybrid experimental-numerical method using various tensile and shear tests. Validation of the proposed model has been done using different tests of two aluminum alloys (Al6061-T6 and Al6014-T4). Through comparisons of numerical simulations with experimental results for different loading paths, the predictive capabilities of the proposed model have been shown. The model is found to be able to capture the initiation as well as propagation of macro-crack in sheet and bulk metals during their forming processes},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{charles_1518,

title = {Mathematical and numerical study of a dusty Knudsen gas mixture},

author = {Frédérique Charles and Francesco Salvarani},

url = {https://link.springer.com/article/10.1007/s10440-019-00277-x},

year  = {2020},

date = {2020-08-01},

journal = {Acta Applicandae Mathematicae},

volume = {168},

number = {1},

pages = {17-31},

abstract = {We consider a mixture composed of a gas and dust particles in a very rarefied setting. Whereas the dust particles are individually described, the surrounding gas is treated as a Knudsen gas, in such a way that interactions occur only between gas particles and dust by means of diffuse reflection phenomena. After introducing the model, we prove the existence and the uniqueness of the solution and provide a numerical strategy for the study of the equations. At the numerical level, we focus our attention on the phenomenon of energy transfer between the gas and the moving dust particles.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{vanaei_2091,

title = {Experimental study of PLA thermal behavior during fused filament fabrication},

author = {Hamidreza Vanaei and Mohammadali Shirinbayani and Sidonie Fernandes Costa and Fernando Moura Duarte and José António Covas and Deligant Michael and Sofiane Khelladi and Abbas Tcharkhtchi},

url = {https://doi.org/10.1002/app.49747},

year  = {2020},

date = {2020-08-01},

journal = {Journal Of Applied Polymer Science},

volume = {138},

number = {4},

pages = {49747},

abstract = {Fused filament fabrication (FFF) is an additive manufacturing technique that is used to produce prototypes and a gradually more important processing route to obtain final products. Due to the layer-by-layer deposition mechanism involved, bonding between adjacent layers is controlled by the thermal energy of the material being printed, which strongly depends on the temperature development of the filaments during the deposition sequence. This study reports experimental measurements of filament temperature during deposition. These temperature profiles were compared to the predictions made by a previously developed model. The two sets of data showed good agreement, particularly concerning the occurrence of reheating peaks when new filaments are deposited onto previously deposited ones. The developed experimental technique is shown to demonstrate its sensitivity to changing operating conditions, namely platform temperature and deposition velocity. The data generated can be valuable to predict more accurately the bond quality achieved in FFF parts.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{vanaei_2090,

title = {Toward the understanding of temperature effect on bonding strength, dimensions and geometry of 3D-printed parts},

author = {Hamidreza Vanaei and Raissi Kaddour and Deligant Michael and Mohammadali Shirinbayani and Joseph Fitoussi and Sofiane Khelladi and Abbas Tcharkhtchi},

url = {https://doi.org/10.1007/s10853-020-05057-9},

year  = {2020},

date = {2020-07-01},

journal = {Journal Of Materials Science},

volume = {55},

pages = {14677-14689},

abstract = {Fused filament fabrication (FFF), which is an additive manufacturing technique, opens alternative possibilities for complex geometries fabrication. However, its use in functional products is limited due to anisotropic strength issues. Indeed, the strength of FFF fabricated parts across successive layers in the build direction (Z direction) can be significantly lower than the strength in X-Y directions. This strength weakness has been attributed to poor bonding between printed layers. This bonding depends on the temperature of the current layer being deposited?at melting temperature (Tm)?and the temperature of the previously deposited layer. It is assumed that depositing a layer at Tm on a layer at temperature around crystallization temperature (Tc) would enable higher material crystallinity and thus better bonding between previous and present layers. On the contrary, if the previous layer temperature is below Tc, material crystallinity will be low and bonding strength weak. This paper aims at studying the significant effect of temperature difference (?T) between previous and current deposited layers temperatures on (1) inter-layers bonding strength improvement and (2) part dimensions, geometry and structure stability. A 23% increase in the inter-layers bonding strength for previous layer temperature slightly higher than Tc reported here confirms the above assumption and offers a first solution toward the increase in inter-layers bonding strength in FFF.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{hamroun_1169,

title = {Existence of large solutions to the Landau-Lifshitz-Bloch equation},

author = {Djamila Hamroun and Kamel Hamdache},

url = {https://www.intlpress.com/site/pub/pages/journals/items/cms/_home/acceptedpapers/index.php},

year  = {2020},

date = {2020-05-14},

journal = {Communications In Mathematical Sciences},

volume = {18},

number = {2},

pages = {487-513},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{vanaei_2087,

title = {Influence of process parameters on thermal and mechanical properties of polylactic acid fabricated by fused filament fabrication},

author = {Hamidreza Vanaei and Mohammadali Shirinbayani and Deligant Michael and Raissi Kaddour and Joseph Fitoussi and Sofiane Khelladi and Abbas Tcharkhtchi},

url = {https://doi.org/10.1002/pen.25419},

year  = {2020},

date = {2020-05-01},

journal = {Polymer Engineering And Science},

volume = {60},

number = {8},

pages = {1822-1831},

abstract = {Fused filament fabrication is considered one of the most used processes in additive manufacturing rapid prototypes out of polymeric material. Poor strength of the deposited layers is still one of the main critical problems in this process, which affects the mechanical properties of the final parts. To improve the mechanical strength, investigation into various process parameters must be considered. In this article, the influence of different process parameters has been experimentally investigated by means of physicochemical and mechanical characterizations. Special attention was given to the thermal aspect. In that respect, the in situ measurement of temperature profile during deposition indicated that several parameters affect the cooling rate of material and consequently have an influence on the final parts. It was found that the influence of increasing the extruder temperature is more significant in comparison with other process parameters.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{hamdache_606,

title = {Weak Solutions to Unsteady and Steady Models of Conductive Magnetic Fluids},

author = {Kamel Hamdache and Djamila Hamroun},

url = {https://link.springer.com/article/10.1007%2Fs00245-018-9505-x},

year  = {2020},

date = {2020-04-01},

journal = {Applied Mathematics And Optimization},

volume = {81},

pages = {479-509},

abstract = {We study a nonlinear coupling system of partial differential equations describing the dynamic of a magnetic fluid with internal rotations. The present mathematical model generalizes those discussed previously in the literature since actually the fluid is electrically conducting inducing additional nonlinearities in the problem and the dynamics of the magnetic field is described by the quasi-static Maxwell equations instead of the usual magnetostatic ones. We prove existence of weak solutions with finite energy first for the unsteady problem then for the steady one.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{plasman_1680,

title = {A projection scheme for Navier--Stokes with  variable viscosity and natural boundary condition},

author = {Ludovic Plasman and Jean Deteix and Driss Yakoubi},

url = {https://onlinelibrary.wiley.com/doi/10.1002/fld.4851},

year  = {2020},

date = {2020-04-01},

journal = {International Journal for Numerical Methods in Fluids},

volume = {92},

number = {12},

pages = {1845-1865},

abstract = {Combiningthe Navier-Stokes systems with Neumann (or natural) boundary condition to characterize a fluid flow is frequent. The popular projection (or pressure

correction) methods inspired by Chorin and Temam are not well adapted to such boundary condition, which translate in loss of accuracy. If some alternative projection methods have been proposed to reduce the accuracy loss due to the Neumann condition in case of Newtonian fluids, little has been pro-

posed for generalized Newtonian fluids. In this work, we propose two methods

derived from the incremental pressure correction projection that can be used

for fluids with inhomogeneous or variable viscosity with natural boundary condition. Both time and space accuracy of the methods will be illustrated using a manufactured solution.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{mula_1514,

title = {Homogenization in the energy variable for a neutron transport model.},

author = {Olga Mula and Francesco Salvarani and Harsha Hutridurga},

url = {https://content.iospress.com/articles/asymptotic-analysis/asy191544},

year  = {2020},

date = {2020-03-01},

journal = {Asymptotic Analysis},

volume = {117},

number = {1-2},

pages = {1-25},

abstract = {This article addresses the homogenization of linear Boltzmann equation when the optical parameters are highly heterogeneous in the energy variable. We employ the method of two-scale convergence to arrive at the homogenization result. In doing so, we show the induction of a memory effect in the homogenization limit. We also provide some numerical experiments to illustrate our results. In the Appendix, we treat a related case of the harmonic oscillator.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{anwasia_1125,

title = {On the Maxwell- Stefan diffusion limit for reactive mixture of polyatomic gases in non-isothermal setting},

author = {Benjamin Anwasia and Marzia Bisi and Ana Jacinta Soares and Francesco Salvarani},

url = {https://www.aimsciences.org/article/doi/10.3934/krm.2020003},

year  = {2020},

date = {2020-02-01},

journal = {Kinetic And Related Models},

volume = {13},

number = {1},

pages = {63-95},

abstract = {In this article we deduce a mathematical model of Maxwell-Stefan type for a reactive mixture of polyatomic gases with a continuous structure of internal energy. The equations of the model are derived in the diffusive limit of a kinetic system of Boltzmann equations for the considered mixture, in the general non-isothermal setting. The asymptotic analysis of the kinetic system is performed under a reactive-diffusive scaling for which mechanical collisions are dominant with respect to chemical reactions. The resulting system couples the Maxwell-Stefan equations for the diffusive fluxes with the evolution equations for the number densities of the chemical species and the evolution equation for the temperature of the mixture. The production terms due to the chemical reaction and the Maxwell-Stefan diffusion coefficients are moreover obtained in terms of general collision kernels and parameters of the kinetic model.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{hamdache_995,

title = {Asymptotics behaviours for the Landau-Lifshitz-Bloch equation},

author = {Kamel Hamdache and Djamila Hamroun},

url = {https://dergipark.org.tr/tr/pub/atnaa/issue/49323/512065},

year  = {2019},

date = {2019-12-01},

journal = {Advances in the Theory of Nonlinear Analysis and its Applications},

volume = {3},

number = {3},

pages = {174-191},

abstract = {The Landau-Lifshitz-Bloch (LLB) equation is an interpolation between Bloch equation valid for high temperatures and Landau-Lifshitz equation valid for low temperatures. Conversely in this paper, we discuss the behaviours of the solutions of (LLB) equation both as the temperature goes to infinity or 0. Surprisingly in the first case, the behaviour depends also on the scaling of the damping parameter   and the volume exchange parameter a. Three cases are considered and accordingly we get either a linear stationary equation, Bloch equation or Stokes equation. As for the small temperature behaviour, d and a being independent of the temperature, we show that the limit of (LLB) equation is Landau-Lifshitz-Gilbert equation.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{ben_abdallah_992,

title = {Enzymatic Hydrolysis of Poly (Caprolactone) and its Blend with Styrene-Butadiene-Styrene (40% PCL/60% SBS)},

author = {Abir Ben Abdallah and Achraf Kallel and Fehmi Gamaoun and Abbas Tcharkhtchi},

url = {https://link.springer.com/article/10.1007%2Fs10924-019-01522-y},

year  = {2019},

date = {2019-11-01},

journal = {Journal Of Polymers And The Environment},

volume = {27},

pages = {2341-2351},

abstract = {In this study, we aim to evaluate the effect of enzymatic hydrolysis on aliphatic polyester and on its shape memory blend. Therefore, the hydrolysis of poly (?-caprolactone) (PCL) and of its shape memory polymer (SMP) blend [40% PCL/60% styrene-butadiene-styrene (SBS)] in a solution containing an Amano lipase from pseudomonas fluorescence and a phosphate buffered saline (PBS), is achieved. An appropriate characterization helps to better understand the behaviour of these polymers. So, the properties of these materials prior and after hydrolytic degradation are investigated. When they are submitted to enzymatic hydrolysis, the physico-chemical and mechanical properties of PCL and its blend (PCL/SBS) change. PCL undergoes a significant decrease in weight during enzymatic hydrolysis. Yet, blending PCL with SBS considerably reduces its degradation rate in terms of weight drop, compared with pure PCL. The enzymatic hydrolysis causes chains splitting, which rises their mobility and facilitates their reorientation. Consequently, for PCL and its blend, the degree of crystallinity Xc rises during hydrolytic degradation, which confirms that the amorphous regions of PCL are more susceptible to hydrolysis. Besides, this continuous rise in crystallinity causes the augmentation of PCL and its blend melting, crystallization and glass transition temperatures. Moreover, the PCL brittleness increases, and the blend ductility decreases with the enzymatic hydrolysis time. For both, PCL and its blend, the young modulus displays two opposite effects; it goes up due the growth of crystallinity, but at the end of hydrolysis, its value goes down because of weight loss.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nguyen_1496,

title = {Role of the Crystal Lattice Structure in Predicting Fracture Toughness},

author = {Thuy Nguyen and Daniel Bonamy},

url = {https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.123.205503},

year  = {2019},

date = {2019-11-01},

journal = {Physical Review Letters},

volume = {123},

number = {20},

pages = {205503},

abstract = {We examine the atomistic scale dependence of a material's resistance to failure by numerical simulations and analytical analysis in electrical analogs of brittle crystals. We show that fracture toughness depends on the lattice geometry in a way incompatible with Griffith's relationship between fracture and free surface energy. Its value finds its origin in the matching between the continuum displacement field at the engineering scale, and the discrete nature of solids at the atomic scale. The generic asymptotic form taken by this field near the crack tip provides a solution for this matching, and subsequently a way to predict toughness from the atomistic parameters with application to graphene},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{yakoubi_1683,

title = {An adaptive discontinuous Galerkin method for very stiff systems of ordinary differential equations},

author = {Driss Yakoubi and André Fortin},

url = {https://www.sciencedirect.com/science/article/pii/S0096300319302875?via%3Dihub},

year  = {2019},

date = {2019-10-01},

journal = {Applied Mathematics And Computation},

volume = {358},

pages = {330-347},

abstract = {We present a discontinuous Galerkin (DG) method for the numerical solution of stiff systems of ordinary differential equations (ODEs). We use a standard DG variational formulation with polynomials of degree k in each time interval. We show that the method is A-stable for every k. We then introduce a hierarchical Legendre finite element basis and we show that a whole family of approximations can be obtained simply by truncating the last p degrees of freedom from the computed solution. We show that these approximations converge to order in L2-norm and to order in supremum norm. We then show how this can be used to control the error and the time step length. We present numerical examples of solutions on very stiff problems and on stiff problems with very long time integration where the time step length can vary on many orders of magnitude.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{yakoubi_1681,

title = {Shear rate projection schemes for non--Newtonian fluids},

author = {Driss Yakoubi and Jean Deteix},

url = {https://www.sciencedirect.com/science/article/pii/S0045782519303469?via%3Dihub},

year  = {2019},

date = {2019-09-01},

journal = {Computer Methods In Applied Mechanics And Engineering},

volume = {354},

number = {1},

pages = {620-636},

abstract = {The operator splitting approach applied to the Navier-Stokes equations gave rise to various numerical methods for the simulations of the dynamics of fluids. The separate work of Chorin and Temam on this subject gave birth to the so-called projection methods. The most basic of those schemes, the incremental and non-incremental variant (see Guermond et al. 2006) induce an artificial Neumann boundary condition on the pressure. The so-called rotational incremental pressure-correction scheme proposed by Timmermans et al. (1996) gives a consistent equation for the pressure in case of a Newtonian fluids with homogeneous viscosity. In this work we propose a family of projection methods for generalized Newtonian fluids based on an extension of the rotational projection scheme. Called shear rate projections, these methods produce consistent pressure when applied to generalized Newtonian fluids. Accuracy of the methods will be illustrated using a manufactured solution. Numerical experiments for the flow past a cylinder, with a Carreau rheological model, will also be presented},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{kallel_891,

title = {Study of bonding formation between the filaments of PLA in FFF process},

author = {Achraf Kallel and Imade Koutiri and Elham Babaeitorkamani and Alireza Khavandi and Morteza Tamizifar and Mohammadali Shirinbayani and Abbas Tcharkhtchi},

url = {https://www.hanser-elibrary.com/doi/10.3139/217.3718},

year  = {2019},

date = {2019-08-01},

journal = {International Polymer Processing},

volume = {34},

number = {4},

pages = {434-444},

abstract = {Fused filament fabrication (FFF) is an additive manufacturing (AM) process that provides physical objects commonly used for modeling, prototyping and production application. The major drawback of this process is poor mechanical property due to the porous structure of final parts. This process requires careful management of coalescence phenomenon. In this paper, the major influencing factors during the FFF process of poly(lactic acid) (PLA) were investigated experimentally and with a numerical model. It has been shown that the polymer temperature has a significant effect on rheological behavior of PLA especially on adhesion of the filaments. An experimental set-up has been placed in the machine to have the cyclic temperature of the filament. A variation of the polymer temperature influences process parameters such as feed rate, temperature of nozzle and temperature of the platform. The results showed that the amount of polymeric coalescence (neck growth) rises when increasing the feed rate, the nozzle temperature, and the platform temperature. A model to predict the neck growth is proposed. It predicts a lower amount of neck growth value than obtained with experimentally. This difference has been explained as the effect of other phenomena, such as polymer relaxation time, pressure of the nozzle and especially cyclic temperature which is not taken into account in the model.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{yakoubi_1685,

title = {A posteriori error estimates of finite element method for the time--dependent Darcy problem in an axisymmetric domain},

author = {Driss Yakoubi and Ajmia Younes Orfi},

url = {https://www-sciencedirect-com.acces.bibl.ulaval.ca/science/article/pii/S0898122119300409?via%3Dihub},

year  = {2019},

date = {2019-05-01},

journal = {Computers & Mathematics With Applications},

volume = {77},

number = {10},

pages = {2833-2853},

abstract = {We consider the time dependent Darcy problem in a three-dimensional axisymmetric domain and, by writing the Fourier expansion of its solution with respect to the angular variable, we observe that each Fourier coefficient satisfies a system of equations on the meridian domain. We propose a discretization of these equations in the case of general solution. This discretization relies on a backward Euler's scheme for the time variable and finite elements for the space variables. We prove a posteriori error estimates that allow for an efficient adaptivity strategy both for the time steps and the meshes. Computations for an example with a known solution are presented which support the a posteriori error estimate.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{chablat_1791,

title = {Self-motion conditions for a 3-PPPS parallel robot with delta-shaped base},

author = {Damien Charles Chablat and Erika Ottaviano and Swaminath Venkateswaran},

url = {https://www.sciencedirect.com/science/article/pii/S0094114X18320834},

year  = {2019},

date = {2019-05-01},

journal = {Mechanism And Machine Theory},

volume = {135},

number = {5},

pages = {109-114},

abstract = {This paper presents the self-motion conditions of the 3-PPPS parallel robot with an equilateral mobile platform and an equilateral-shaped base. The study of the direct kinematic model shows that this robot admits self-motion of the Cardanic type as the 3-RPR planar parallel robot where the first revolute joint of each leg is actuated or the PamINSA parallel robot. This property explains why the direct kinematic model admits an infinite number of solutions in the center of the workspace but has never been studied until now. The condition of this singularity is described and the location of the self-motion in the workspace with respect to all the singularities is then presented. The quaternion parameters are used to represent the singularity surfaces and the self-motion conditions in the workspace.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{hfaiedh_505,

title = {Interaction between ductile damage and texture evolution in finite polycrystalline elastoplasticity},

author = {Naila Hfaiedh and A. Roos and Houssem Badreddine and Khemais Saanouni},

url = {https://journals.sagepub.com/doi/10.1177/1056789518775179},

year  = {2019},

date = {2019-04-01},

journal = {International Journal Of Damage Mechanics},

volume = {28},

number = {4},

pages = {481-501},

abstract = {In this paper, a multiscale model of ductile damage and its effects on the inelastic behavior of face centered cubic polycrystalline metallic materials, such as the evolution of their crystallographic textures, are investigated. The constitutive equations are written in the framework of rate-dependent polycrystalline plasticity at the microscopic scale. Plasticity and damage are coupled through a ductile damage variable introduced at the scale of the crystallographic slip systems of each grain. When homogenized to the macro-scale, this becomes an approximate phenomenological measure of the macroscopic ductile damage which can describe the material degradation by initiation, growth, and coalescence of micro-defects. In this paper, thermally activated intergranular (or creep) damage is not taken into account. Both theoretical and numerical aspects of the model are presented. The model is implemented into a generalpurpose finite element code in order to analyze the effects of texture evolution and ductile damage initiation in the grains with favorably oriented slip systems. The capability of the proposed model to predict the plastic strain localization and the induced textural evolution, as well as the effects of the ductile damage and its evolution up to the final macroscopic failure are studied for a classical tensile loading path, applied to a representative volume element and to a 3D tensile specimen on which a parametric study has been carried out.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{venkateswaran_1790,

title = {Numerical and Experimental Validation of the Prototype of a Bio-Inspired Piping Inspection Robot},

author = {Swaminath Venkateswaran and Damien Charles Chablat and Frédéric Boyer},

url = {https://www.mdpi.com/2218-6581/8/2/32},

year  = {2019},

date = {2019-04-01},

journal = {Robotics},

volume = {8},

number = {2},

pages = {32},

abstract = {Piping inspection robots are of greater importance for industries such as nuclear, chemical and sewage. Mechanisms having closed loop or tree-like structures can be employed in such pipelines owing to their adaptable structures. A bio-inspired caterpillar type piping inspection robot was developed at Laboratoire des Sciences du Numérique de Nantes (LS2N), France. Using DC motors and leg mechanisms, the robot accomplishes the locomotion of a caterpillar in six-steps. With the help of Coulomb's law of dry friction, a static force model was written and the contact forces between legs of robot and pipeline walls were determined. The actuator forces of the DC motors were then estimated under static phases for horizontal and vertical orientations of the pipeline. Experiments were then conducted on the prototype where the peak results of static force analysis for a given pipe diameter were set as threshold limits to attain static phases inside a test pipeline. The real-time actuator forces were estimated in experiments for similar orientations of the pipeline of static force models and they were found to be higher when compared to the numerical model.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{benjeddou_892,

title = {Free vibration of actual aircraft and spacecraft hexagonal honeycomb sandwich panels: A practical detailed FE approach},

author = {Ayech Benjeddou and Mohamed Guerich},

url = {http://koreascience.or.kr/article/JAKO201913457808231.page},

year  = {2019},

date = {2019-03-01},

journal = {Advances in Aircraft and Spacecraft Science},

volume = {6},

number = {2},

pages = {169-187},

abstract = {This work presents a practical detailed finite element (FE) approach for the three dimensional (3D) free vibration analysis of actual aircraft and spacecraft type lightweight and thin honeycomb sandwich panels. It consists of calling successively in MATLAB®, via a developed user friendly GUI, a detailed 3D meshing tool, a macro commands language translator and a commercial FE solver (ABAQUS® or ANSYS®). In contrary to the common practice of meshing finely the faces and core cells, the proposed meshing tool represents each wall of the actual hexagonal core cells as a single two dimensional (2D) 4 nodes quadrangular shell element or two 3 nodes triangular ones, while the faces meshes are obtained simply using the nodes at the core faces interfaces. Moreover, as the same 2D FE interpolation type is used for meshing the core and faces, this leads to an automatic handling of their required FE compatibility relations. This proposed approach is applied to a sample made of very thin glass fiber reinforced polymer woven composite faces and a thin aluminum alloy hexagonal honeycomb core. The unknown or incomplete geometric and materials properties are first collected through direct measurements, reverse engineering techniques and experimental FE modal analysis based inverse identification. Then, the free vibrations of the actual honeycomb sandwich panel are analyzed experimentally under different boundary conditions and numerically using different mesh basic cell shapes. It is found that this approach is accurate for the first few modes used for pre design purpose.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{amirat_895,

title = {Weak solutions to stationary equations of heat transfer in a magnetic fluid},

author = {Youcef Amirat and Kamel Hamdache},

url = {https://www.aimsciences.org/article/doi/10.3934/cpaa.2019035},

year  = {2019},

date = {2019-03-01},

journal = {Communications On Pure And Applied Analysis},

volume = {18},

number = {2},

pages = {709-734},

abstract = {We consider the differential system describing the stationary heat transfer in a magnetic fluid in the presence of a heat source and an external magnetic field. The system consists of the stationary incompressible Navier-Stokes equations, the magnetostatic equations and the stationary heat equation. We prove, for the differential system posed in a bounded domain of R3  and equipped with Fourier boundary conditions, the existence of weak solutions by using a regularization of the Kelvin force and the thermal power.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}