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The purpose of this paper is to present the results of interaction occurring during the exposition of some specific carbon textile materials obtained in laboratory conditions to beams of various laser types.

Carbon fabric materials – fiber, felt and cloth – obtained from different precursor materials and prepared at various process conditions (oxidized, partially carbonized, carbonized, graphitized), were exposed to pulses of various lasers (Nd3+: YAG, alexandrite, ruby).

Depending on the laser power, plasma and destructive phenomena occurred. In the case of an interaction between a Nd3+: YAG laser beam and specimens of thickness in millimeter range, the authors have estimated the threshold of the energy density for drilling and discussed the possible models of the interaction.

The results have implications in the estimations of quality as well as in the improvement of material processing, giving some new light to the changes of mechanical and optical constants of the material, as well as to the changes of carbon groups of the material, which would be useful for different types of modeling. Future research will be in the interaction of laser beams with various textile materials, where the investigation would cover the microstructure changes and the implications on cloth cutting and welding, concerning the damages as well as relief structures, specially renew for fs laser regimes.

The area of laser applications in the textile industry is supported by scientific and applicative exploration. However, fewer results are concerned with deep introspection into the microstructure of the damages considering the laser interaction with carbon fiber and other carbon-based textiles.

This paper aims to develop efficient and simple models for thermal distribution, melt pool dimensions and controlled phase change in the laser additive manufacturing (AM) of bulk and powder particles ceramic materials.

This paper proposes new analytical models for the AM of bulk and powder bed ceramic materials. A volumetric moving heat source, along with the complete melting of bulk and powder particle materials, is taken into account. Different values of laser absorption coefficient in solid and liquid states have been used to investigate the phase transformation. Furthermore, the pores and voids dimensions are also included in the modeling. Theoretical predictions have been compared with the experimental analyses and finite element simulations in laser to silicon nitride and laser to alumina interaction. The analysis focuses on the impact of laser power and scanning speed on the melt pool width and depth evolution into the bulk substrate and powder bed.

This study shows that the powder particles exhibit a higher thermal distribution value than the bulk substrate because of voids in the powder layer. The laser beam experiences multiple reflections in the presence of porosity/voids, thus increasing the surface absorption coefficient, which becomes relevant with the increment in the pore/void dimension. A direct relationship has been found between the laser power and melt pool dimensions, while the scanning speed displayed an inverse relationship for the melt pool width and length. Larger melt dimensions were inferred in the case of laser–powder particle interaction compared with laser–bulk substrate interaction. A close correlation was found between the analytical simulations, experimental investigations and numerical simulation results within the range of 4%–8%.

This paper fulfills an identified need to develop efficient and simplified models for ceramics laser AM by taking into account different laser absorption coefficients in solid and liquid form, voids and pores dimensions and controlled phase transformation to avoid vapors and plasma formation. The limitation of the finite element simulation model is that the solution is strongly dependent on the mesh quality and accuracy directly linked to the computation efficiency and time. A finer mesh requires a longer computing time than a coarse mesh. Finite element simulations require, however, specialized skills.

The aim of this paper is to develop and validate a model and a numerical code describing the laser matter interaction and also laser ablation. The laser wavelength is 193 nm and the pulse duration is several nanoseconds.

The developed model is based on strong theoretical background (cf. references). The electronic nonequilibrium aspect is always taken into account. The electronic nonequilibrium is one of the key aspect the UV laser matter interaction and must be treated carefully and that is not always the case. The numerical code was developed using efficient and versatile numerical methods. The model and simulations are always compared to experiments in order to validate them and also to find their limitations.

This work has greatly improved the code accuracy. The key role of the electronic nonequilibrium is also demonstrated. From experimental comparisons it is obvious that photo‐ablation should be taken into account for the lower fluences, but to do so, a completely new approach must be developed.

This work describes the whole laser ablation process with the electronic nonequilibrium effects properly modeled. The numerical results has always been confronted to experiments, in most of the cases the agreement was very good. When it was not the case, explanations have been sought along with ways to improve the approach.

This paper aims to investigate the effect of four important process parameters (i.e. laser focal distance, travel speed, feeding gas flow rate and standoff distance) on the size of single clad geometry created by coaxial nozzle-based powder deposition by high power laser.

Design of experiments (DOE) and statistical analysis methods were both used to find optimum parameter combinations to get minimum sized clad, i.e. clad width and clad height. Factorial experiment arrays were used to design parameter combinations for creating experimental runs. Taguchi optimization methodology was used to find out optimum parameter levels to get minimum sized clad geometry. Response surface method was used to investigate the nonlinearity among parameters and variance analysis was used to assess the effectiveness level of each problem parameters.

The overall results show that wisely selected four problem parameters have the most prominent effects on the final clad geometry. Generally, minimum clad size was achieved at higher levels of gas flow rate, travel speed and standoff distance and at minimum spot size level of the laser focal distance.

This study presents considerable contributions in assessing the importance level of problems parameters on the optimum single clad geometry created laser-assisted direct metal part fabrication method. This procedure is somewhat complicated in understanding the effects of the selected problem parameters on the outcome. Therefore, DOE methodologies are utilized so that this operation can be better modeled/understood and automated for real life applications. The study also gives future direction for research based on the presented results.

Hydroxyapatite‐polymer composite materials are being researched for the development of low‐load bearing implants because of their bioactive and osteoconductive properties, while avoiding modulus mismatch found in homogenous materials. For the direct production of hydroxyapatite‐polymer composite implants, selective laser sintering (SLS) has been used and various parameters and their effects on the physical properties (micro and macro morphologies) have been investigated. The purpose of this paper is to identify the most influential parameters on the micro and macro pore morphologies of sintered hydroxyapatite‐polymer composites.

A two‐level full factorial experiment was designed to evaluate the effects of the various processing parameters and their effects on the physical properties, including open porosity, average pore width and the percentage of pores which could enable potential bone regeneration and ingrowth of the sintered parts. The density of the sintered parts was measured by weight and volume; optical microscopy combined with the interception method was used to determine the average pore size and proportion of pores suitable to enable bone regeneration.

It was found that the effect of build layer thickness was the most influential parameter with respect to physical and pore morphology features. Consequently, it is found that the energy density equation with the layer thickness parameter provides a better estimation of part porosity of composite structures than the energy density equation without the layer thickness parameter. However, further work needs to be conducted to overcome the existing error of variance.

This work is the first step in identifying the most significant SLS parameters and their effects on the porosity, micro and macro pore morphologies of the fabricated parts. This is an important step in the further development of implants which may be required.

Selective laser sintering (SLS) is one of the most rapidly growing rapid prototyping techniques (RPT). This is mainly due to its suitability to process almost any material: polymers, metals, ceramics (including foundry sand) and many types of composites. The material should be supplied as powder that may occasionally contain a sacrificial polymer binder that has to be removed (debinded) afterwards. The interaction between the laser beam and the powder material used in SLS is one of the dominant phenomena that defines the feasibility and quality of any SLS process. This paper surveys the current state of SLS in terms of materials and lasers. It describes investigations carried out experimentally and by numerical simulation in order to get insight into laser‐material interaction and to control this interaction properly.

The purpose of this paper is to optimise the selective laser melting (SLM) process parameters for CMSX486 to produce a “void free” (fully consolidated) material, whilst reducing the cracking density to a minimum providing the best possible fabricated material for further post-processing. SLM of high temperature nickel base superalloys has had limited success due to the susceptibly of the material to solidification and reheat cracking.

Samples of CMSX486 were fabricated by SLM. Statistical design of experiments (DOE) using the response surface method was used to generate an experimental design and investigate the influence of the key process parameters (laser power, scan speed, scan spacing and island size). A stereological technique was used to quantify the internal defects within the material, providing two measured responses: cracking density and void per cent.

The analysis of variance (ANOVA) was used to determine the most significant process parameters and showed that laser power, scan speed and the interaction between the two are significant parameters when considering the cracking density. Laser power, scan speed, scan spacing and the interaction between power and speed, and speed and spacing were the significant factors when considering void per cent. The optimum setting of the process parameters that lead to minimum cracking density and void per cent was obtained. It was shown that the nominal energy density can be used to identify a threshold for the elimination of large voids; however, it does not correlate well to the formation of cracks within the material. To validate the statistical approach, samples were produced using the predicted optimum parameters in an attempt to validate the response surface model. The model showed good prediction of the void per cent; however, the cracking results showed a greater deviation from the predicted value.

This is the first ever study on SLM of CMSX486. The paper shows that provided that the process parameters are optimised, SLM has the potential to provide a low-cost route for the small batch production of high temperature aerospace components.

This paper aims to provide a review on the process of additive manufacturing of ceramic materials, focusing on partial and full melting of ceramic powder by a high-energy laser beam without the use of binders.

Selective laser sintering or melting (SLS/SLM) techniques are first introduced, followed by analysis of results from silica (SiO₂), zirconia (ZrO₂) and ceramic-reinforced metal matrix composites processed by direct laser sintering and melting.

At the current state of technology, it is still a challenge to fabricate dense ceramic components directly using SLS/SLM. Critical challenges encountered during direct laser melting of ceramic will be discussed, including deposition of ceramic powder layer, interaction between laser and powder particles, dynamic melting and consolidation mechanism of the process and the presence of residual stresses in ceramics processed via SLS/SLM.

Despite the challenges, SLS/SLM still has the potential in fabrication of ceramics. Additional research is needed to understand and establish the optimal interaction between the laser beam and ceramic powder bed for full density part fabrication. Looking into the future, other melting-based techniques for ceramic and composites are presented, along with their potential applications.

The consolidation process and morphology evolution in ceramics-based additive manufacturing (AM) are still not well-understood. As a way to better understand the ceramic selective laser sintering (SLS), a dynamic three-dimensional computational model was developed to forecast thermal behavior of hydroxyapatite (HA) bioceramic.

AM has revolutionized automotive, biomedical and aerospace industries, among many others. AM provides design and geometric freedom, rapid product customization and manufacturing flexibility through its layer-by-layer technique. However, a very limited number of materials are printable because of rapid melting and solidification hysteresis. Melting-solidification dynamics in powder bed fusion are usually correlated with welding, often ignoring the intrinsic properties of the laser irradiation; unsurprisingly, the printable materials are mostly the well-known weldable materials.

The consolidation mechanism of HA was identified during its processing in a ceramic SLS device, then the effect of the laser energy density was studied to see how it affects the processing window. Premature sintering and sintering regimes were revealed and elaborated in detail. The full consolidation beyond sintering was also revealed along with its interaction to baseplate.

These findings provide important insight into the consolidation mechanism of HA ceramics, which will be the cornerstone for extending the range of materials in laser powder bed fusion of ceramics.

During thermal laser processes, heat transfer and fluid flow in the melt pool are primary driven by complex physical phenomena that take place at liquid/vapor interface. Hence, the choice and setting of front description methods must be done carefully. Therefore, the purpose of this paper is to investigate to what extent front description methods may bias physical representativeness of numerical models of laser powder bed fusion (LPBF) process at melt pool scale.

Two multiphysical LPBF models are confronted: a Level-Set (LS) front capturing model based on a C++ code and a front tracking model, developed with COMSOL Multiphysics® and based on Arbitrary Lagrangian–Eulerian (ALE) method. To do so, two minimal test cases of increasing complexity are defined. They are simplified to the largest degree, but they integrate multiphysics phenomena that are still relevant to LPBF process.

LS and ALE methods provide very similar descriptions of thermo-hydrodynamic phenomena that occur during LPBF, providing LS interface thickness is correctly calibrated and laser heat source is implemented with a modified continuum surface force formulation. With these calibrations, thermal predictions are identical. However, the velocity field in the LS model is systematically underestimated compared to the ALE approach, but the consequences on the predicted melt pool dimensions are minor.

This study fulfils the need for comprehensive methodology bases for modeling and calibrating multiphysical models of LPBF at melt pool scale. This paper also provides with reference data that may be used by any researcher willing to verify their own numerical method.