Jonas de Carvalho

A novel multiobjective optimization algorithm based on bacterial chemotaxis

In this article a novel algorithm based on the chemotaxis process of Echerichia coli is developed to solve multiobjective optimization problems. The algorithm uses fast nondominated sorting procedure, communication between the colony members and a simple chemotactical strategy to change the bacterial positions in order to explore the search space to find several optimal solutions. The proposed algorithm is validated using 11 benchmark problems and implementing three different performance measures to compare its performance with the NSGA-II genetic algorithm and with the particle swarm-based algorithm NSPSO.

A procedure to estimate the dynamic damped behavior of fiber reinforced composite beams submitted to flexural vibrations

This work proposes a procedure to estimate the dynamic damped behavior of fiber reinforced composite beams in flexural vibrations. A set of experimental dynamic tests were carried out in order to investigate the natural frequencies and modal shapes. These results are used to evaluate the damping factors by the program FREQ. These damping factors are then used as input to a damped dynamic analysis by the Finite Element Method, using Rayleigh Model. A good agreement between theoretical and experimental results was obtained. Thus, it became possible to validate the proposed procedure to evaluate dynamic damped behavior of composite beams.

Optimization of positioning system of FDM machine design using analytical approach

Purpose – The purpose of this paper is to analyse the conception of the positioning system of fused deposition modeling (FDM) machines, optimising design parameter and components accuracy to decrease mechanical errors of equipment, which, consequently, results in the increase of parts accuracy. This paper also reports studies related to analytical estimation of machine errors, describing a theoretical model which was used for the multivariable study. Additionally, an alternative conception is proposed, according with the result of this study.Design/methodology/approach – For elaboration of the numerical model of equipment, the authors have focused on conception of first generation of FDM, specifying as design parameters, timing belt stiffness, linear bearing clearance, and accuracy grade of ball screw housing, support and pulley. In order to identify the main effect of each design parameter for the final error of machine, the authors have applied a multivariable method in addition to identifying the error...

Development of acrylate-based material using a multivariable approach: additive manufacturing applications

Purpose – Over the last several years, the range of applications for the photopolymerisation process has been steadily increasing, especially in such areas as rapid prototyping, UV inks, UV coats and orthodontic applications. In spite of this increase, there are still several challenges to be overcome when the application concerns materials formulation and their mechanical properties. In this context, the main aim of this work is to outline the contribution of the formulation components for the parameters of the photopolymerisation process and the resultant mechanical properties of the material. Design/methodology/approach – For this research, the authors have applied multivariable analysis methods, which allow the identification of principal conclusions based on experimental results. For the experimental analysis, the authors applied design of experiment, while the material formulation was based on methyl methacrylate as a monomer, Omnrad 2500 as a photoinitiator and trimethylolpropane triacrylate as an ...

Design of an FDM positioning system and application of an error‐cost multiobjective optimization approach

Purpose – As a result of the increased number of applications for additive manufacturing technologies and in addition to the demand for parts produced with high accuracy and better quality, the need for the improvement of positioning and precision equipment in manufacturing has become evident. To address this needed improvement, the main goal of this work is to provide a systematic approach for designing additive manufacturing machines, allowing the identification of the relationship between estimated errors and the cost of equipment. In the same way, this study also intends to indicate a suitable configuration of a machine as a function of final accuracy and total equipment cost.Design/methodology/approach – To identify the suitable elements of the machine, a numerical model that estimates the final error and relative cost of equipment as a function of cost and tolerance of the machine elements was constructed and evaluated. After evaluating this model by comparing it with first‐generation fused depositi...

Compression tests of castor oil biopolymer

Many methods have been developed to test and evaluate the mechanical properties of the biopolymer from castor oil employed in implants and osteo-repositions, among other things. Most of the methods are performed under quasi-static and cyclic loads (creep and relaxation tests) and under high strain rate, uniaxial compression conditions. This paper presents and discusses the development and applicability of a simple load-application apparatus, devised to reduce shear and barrelling effects on specimens and allow for conventional strain around 45%. Besides contributing valuable information on the mechanical behavior of the castor oil polyurethane, the results of this research point to multiple biomedical applications for this material.

Development of novel additive manufacturing technology: an investigation of a selective composite formation process

Purpose – The purpose of this study is to present a novel additive manufacturing (AM) technology which is based on selective formation of cellulose-acrylate composite. Besides proposing a process that combines the benefits of fibres and photopolymers, this paper reports the development of material, characterisation of a straight line composite formation, adherence between layers and functional feasibility of the proposed concept. Design/methodology/approach – For the preliminary evaluation of the proposed process, a composite material based on cellulose-photopolymer was developed, while a multi-objective optimisation study indicated the formulation which results in the maximum values of layer adherence, tensile strength of composite and the effect of the water on the mechanical strength of material. For the characterisation of the process, three main subjects were analysed: the characterisation of straight line composite formation, the effect of composite formation process on previous layers and the funct...

Deployment of a laser projection solution for stripes plotting based on Six Sigma DMAIC methodology applied to aircraft painting shop

This paper aims to demonstrate the advantages of using DMAIC Six Sigma method to implement a laser projection system for stripes plotting in aircraft painting shop. The main benefits of this solution are to increase the productivity, improve the final quality of the product, reduce the reworks and consumable materials, as well as attend to the requirements of ergonomics, occupational health, and safety. Thus, better results are expected in terms of process efficiency and technological innovation that are competitive market requirements. Also, it can contribute to improving the painting process of the aircraft, striving for excellence in the processes, thereby reducing the costs of manufacturing and providing greater customer satisfaction. A case study is shown to prove the benefits.

Optimization of thick layers photopolymerization systems applying experimental and analytical approach

Purpose – Over the last several years, the range of applications of photopolymerization process has been steadily increasing, especially in areas such as rapid prototyping, UV inks, UV coats and orthodontic applications. In spite of this, there are still several challenges to be overcome when the application concerns materials with thick layers. In this context, the main goal of this work is to outline a scheme to optimize the process of photopolymerizarion for thick layers, identifying its differences in relation to those applicable for thin layers.Design/methodology/approach – For this research, the authors have applied multivariable analysis methods which allow the identification of principal conclusions, based on analytical and experimental results. For analytical analysis, the authors applied numerical optimization for multivariables, while experimental analysis was done based on design of experiments. Both the analyses were based on methyl methacrylate as monomer and Omnirad 2500 as photoinitiator, ...

Design for Manufacturing and Assembly methodology applied to aircrafts design and manufacturing

This paper presents a guideline which uses the concepts of DFMA (Design for Manufacturing and Assembly) methodology for specific application on aircrafts design and manufacturing. The main goal of the guideline is to guide the engineers during the aircraft development phases, such that a better aircraft design is achieved. The guideline provides a better evaluation of manufacturing processes, assembly, maintenance, capability and human factors (ergonomics). It is expected to improve the manufacturing and simplify the assembly to become easier the manufacturing of parts that will make the aircraft final assembly with low costs, high quality and the best optimized condition. A case study is showed to testify the advantages and benefits achieved when the proposed tool is used.