André Chateau Akué Asséko

IMT Nord Europe · CERI Matériaux et Procédés

Most of everyday products and industrial structures are made by the assembly of several parts and therefore contain joints. This is the case for example in the aeronautics, railway or automotive industry where polymer composites become more and more popular as lightweight substitutes of metallic materials. Joining of polymer composites may be achie...

3D printing has offered cost-effective, lightweight, and complex parts. To extend their applications, 3D printed parts need to be welded in order to form the larger functional assemblies. For this purpose, Laser Transmission Welding (LTW) is a promising joining technology. This paper aims to investigate the light scattering effect on the intensity...

The present study investigated the influence of temperature on molecular interdiffusion at the interface during the laser transmission welding of 3D-printed continuous carbon-fiber-reinforced thermoplastic composites. In order to accurately measure the temperature at the weld interface, a series of thermocouples were embedded in the laser-absorbent...

The determination of the laser intensity profile necessary to weld two thermoplastic parts is crucial for understanding and optimizing the laser welding process in polymers and composite materials. Traditional methods of measuring the laser beam intensity profile, such as laser beam profiling techniques, can be difficult to implement and expensive....

Laser transmission welding (LTW) is a suitable process for assembling thermoplastic materials. This joining process is used to assemble most thermoplastics, but high-performance thermoplastics, such as polyetherketoneketone (PEKK), have received less attention until now. The present work deals with joining PEKK parts by LTW in amorphous over semi-c...

The present paper addresses experimental and numerical investigations of a Large Scale Additive Manufacturing (LSAM) process using polymers. By producing large components without geometrical constraints quickly and economically, LSAM processes have the capability to revolution- ize many industries. Accurate prediction and control of the thermal his...

Laser transmission welding is a widely used process for joining thermoplastics. Of the two materials involved in the welding process, one should be transparent/semi-transparent to laser wavelength, and the other absorbent to the same wavelength. A laser beam is transmitted through the transparent material and is absorbed at the interface of the two...

In this work, a numerical method is presented in order to simulate the deposition of molten polymer bead onto a substrate and its cooling down in the large-scale extrusion-based additive manufacturing process. The polymer flow is treated as a single-phase flow with a free surface. This method reduces the computation time without loss of accuracy as...

An inverse method for determining the in-plane effective thermal conductivity of porous thermoplastics was implemented by coupling infrared thermography experiments and numerical simulation of heat transfer in straight fins having temperature-dependent convective heat transfer coefficient. The microstructure heterogeneity of extruded polyethylene f...

Transmission laser welding (TLW) is an environmentally friendly and versatile process for assembling polymeric parts. Welding by transmission requires the upper element to be transparent to the laser wavelength whereas the inferior part is absorbent to the same wavelength. Thus, the energy of the laser beam is concentrated at the interface, allowin...

Laser Transmission Welding process (LTW) is a well know technic for polymer welding. This technic can also be applied to thermoplastic glass fiber composite (polymer + continuous glass fibers). But in this case two phenomenon occur and are able to make the welding in a poor quality: light absorption and light scattering. The two phenomenon occurrin...

This paper addresses heat distribution issues in Fused Filament Fabrication (FFF) process. 3D Numerical simulations and experimental investigations are performed during additive manufacturing of parts by FFF process. The transient numerical simulations of the filament temperature field are based on the finite difference method. Experimental measure...

The aim of this paper is to develop a cost-effective, efficient and fast experimental optical method to predict the optical properties (extinction coefficient) of semi-transparent glass-fibre-reinforced polymer composites. The extinction coefficient takes into account the effects due to the absorption and the scattering phenomena in a semi-transpar...

The purpose of this paper is to develop a cost-effective, efficient and quick to implement experimental optical method in order to predict the optical properties (extinction coefficient) of semi-transparent polymer composites. The extinction coefficient takes into account the effects due to the absorption and the scattering phenomena in a semi-tran...

An inverse method for determining the in-plane effective thermal conductivity of porous thermoplastics was implemented by coupling infrared thermography experiments and numerical solution of heat transfer in straight fins having temperature-dependent convective heat transfer coefficient. The obtained effective thermal conductivity values were compa...

Key relationships between foam morphologies and melt-state rheological parameters are here exposed for biobased poly(butylene-succinate) (PBS) and standard petrobased polyethylene (PE) foams processed by single-screw extrusion. Scanning electron microscopy followed by image analysis revealed cell diameters and densities in the range of 250–700 µm a...

This study is dedicated to the development of a numerical finite-element solution to determine the effective thermal conductivity of extruded polymeric foam with different levels of open and closed porosity. The implemented numerical method is derived from periodic homogenization techniques used for the simulation of laser welding of composite mate...

In this study, the effects of the welding temperature field developed during the infrared assembly process on the joining properties of glass fibre reinforced polycarbonate/unreinforced polycarbonate with carbon black were investigated. The temperature field and the contact time govern together the quality of the adhesion at the welding interface....

In this study, the effects of the welding temperature field developed during the infrared assembly process on the joining properties of glass fibre reinforced polycarbonate/ unreinforced polycarbonate with carbon black were investigated. The temperature field and the contact time govern together the quality of the adhesion at the welding interfac...

In this study, the effects of the welding temperature field developed during the infrared assembly process on the joining properties of glass fibre reinforced polycarbonate/ unreinforced polycarbonate with carbon black were investigated. The temperature field and the contact time govern together the quality of the adhesion at the welding interface....

In this study, the effects of the welding temperature field developed during the infrared assembly process on the joining properties of glass fibre reinforced polycarbonate/ unreinforced polycarbonate with carbon black were investigated. The temperature field and the contact time govern together the quality of the adhesion at the welding interface....

In this paper, experimental measurements are performed to confirm the global analytical model (refraction and absorption phenomena) presented in the previous work. Initially, an experimental approach to the estimation of the laser beam spread in a semi-transparent composite and at interface (width of the output beam) subjected to an incident heat f...

In the present study, thermophysical and optical characterization of UD thermoplastic composites materials have been investigated. Knowledge of these parameters is of utmost importance to better understanding of any process that involves laser processing of materials. These properties play an important role during the simulation of the welding proc...

In this paper, experimental measurements are performed to confirm the global analytical model (refraction and absorption phenomena) presented in the previous work. Initially, an experimental approach to the estimation of the laser beam spread in a semi-transparent composite and at interface (width of the output beam) subjected to an incident heat f...

In previous studies [1, , we have presented a detailed formulation of a macroscopic analytical model of the optical propagation of laser beams in the case of unidirectional thermoplastic composites materials. This analytical model presented a first step which concerns the estimation of the laser beam intensity at the welding interface. It describes...

Analytical and numerical models for laser beam scattering in the thermoplastics composites are presented. The numerical model is based on Ray Tracing, an optical method to compute the optical propagation of laser beams in inhomogeneous media with spatially varying dispersion of the refractive index. In this study, only the case of unidirectional th...