Mechanics of thrust force on chisel edge in carbon fiber reinforced polymer (CFRP) drilling based on bending failure theory

ABSTRACT Amongst the many additive manufacturing (AM) techniques, directed energy deposition (DED) is a prominent one, which can also be used for the repair of damaged components. In this paper, we provide an overview on it, with emphasis on the typical microstructures of DED alloys and discuss the processing-microstructure-mechanical property correlations. Comparison is made with those manufactured using the conventional techniques and those obtained with laser beam powder bed fusion (LB-PBF). The characteristic solidification rates and thermal histories in DED result in distinct micro- and meso-structural features and mechanical performance, which are succinctly summarized. The potential of DED for manufacturing graded materials and for component repair is elaborated while highlighting the key-associated challenges and possible solutions. Modelling and simulation studies that facilitate an in-depth understanding of the DED technique are summarized. Finally, some critical issues and research directions that would help develop DED further and extend its application potential are identified.

Directed energy deposition of metals: processing, microstructures, and mechanical properties

Machining parameters affects the final quality of components made in carbon fiber reinforced plastic (CFRP) composite materials. In this framework, the work here presented aims at studying the right combination of cutting speed (vc) and feed rate (vf), for dry drilling of carbon fiber reinforced plastic composite materials, which obtained better results regarding roughness, hole cylindricity, and diameter. A series of experimental tests were carried out under different drilling conditions (vc/vf), monitoring the thrust force (Fz), torque (T), and electric power (EP), to define which one can help more for industrial daily life production. Results validation was carried out using the analysis of variance, in order to relate main machining parameters cutting speed and linear feed, with thrust force, drilling torque, main spindle electric power and hole quality parameters (average roughness, cylindricity and diameter). The conclusions show that thrust force is not proportional to the cutting speed and the best combinations of cutting speed and feed were found out around the average values of tested parameters. Spindle electric power is an interesting element to take into account because it is easy to consider in real production.

Multiple Sensor Monitoring of CFRP Drilling to Define Cutting Parameters Sensitivity on Surface Roughness, Cylindricity and Diameter

Additive manufacturing of oxide-dispersion strengthened alloys: materials, synthesis and manufacturing

The practical application of a multi-objective optimization strategy based on evolutionary algorithms was proposed to optimize the plastics thermoforming process. For that purpose, in this work, differently from the other works proposed in the literature, the shaping step was considered individually with the aim of optimizing the thickness distribution of the final part originated from sheets characterized by different thickness profiles, such as constant thickness, spline thickness variation in one direction and concentric thickness variation in two directions, while maintaining the temperature constant. As far we know, this is the first work where such a type of approach is proposed. A multi-objective optimization strategy based on Evolutionary Algorithms was applied to the determination of the final part thickness distribution with the aim of demonstrating the validity of the methodology proposed. The results obtained considering three different theoretical initial sheet shapes indicate clearly that the methodology proposed is valid, as it provides solutions with physical meaning and with great potential to be applied in real practice. The different thickness profiles obtained for the optimal Pareto solutions show, in all cases, that that the different profiles along the front are related to the objectives considered. Also, there is a clear improvement in the successive generations of the evolutionary algorithm.

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Multi-objective optimization of plastics thermoforming

Investigation of temperature distribution and solidification morphology in multilayered directed energy deposition of Al-0.5Sc-0.5Si alloy

Pressure thermoforming is one of the most widely used thermoplastic processing technique where a polymer sheet is deformed using gas pressure. Pressure forming is not suitable in applications such as airplane canopies where precise control over dimensions is required, because of the drawback of uneven thickness distribution of the product. The current work seeks to find a way to use the pressure forming technique to produce components having uniform thickness distribution. The deformation process of PMMA sheet into a hemispherical dome using pressure thermoforming is numerically analyzed and the concept of provision of initial thickness distribution to the sheet is proposed.

A numerical approach on achieving uniform thickness distribution in pressure thermoforming

Prediction of Thrust Force and Torque in Drilling of Glass Fiber Reinforced Plastic Using Mechanistic Force Model Approach

The ability to produce products with more uniformity in the wall thickness distribution makes contact thermoforming the most suitable optical product processing method. Among all the process parameters, the contact condition significantly affects the structural strength and the optical properties of the product. Thus, it is imperative to investigate the effect of change in the contact conditions on product thickness. Hence, in this study, experimental investigations on contact conditions were performed considering poly(methyl methacrylate) as the sheet material and stainless steel 304 as the punch material. Experiments were conducted to examine the effect of temperature on the coefficient of friction (mechanical contact condition) and the effect of pressure on the thermal contact conductance (thermal contact condition). It was found that the contact conditions change significantly with changes in the operating conditions. Furthermore, numerical simulations were performed, considering isothermal processing and nonisothermal processing with constant and variable contact conditions to identify the effect of the change in contact condition on the product thickness. It was found that the change in contact condition has a considerable effect on the product thickness distribution. This study shows the importance of incorporation of the change in the contact condition for realistic simulations.

Jeet P. Patil

Papers

Investigation of temperature distribution and solidification morphology in multilayered directed energy deposition of Al-0.5Sc-0.5Si alloy

A numerical approach on achieving uniform thickness distribution in pressure thermoforming

Prediction of Thrust Force and Torque in Drilling of Glass Fiber Reinforced Plastic Using Mechanistic Force Model Approach

Contact Analysis for Contact Thermoforming of PMMA Sheet

Transient thermal analysis of close pressure thermoforming process