Fuzzy rule based optimization in machining of glass fiber reinforced polymer (GFRP) composites

With the increasing use of Fiber Reinforced Polymer (FRP) composites outside the defense, space and aerospace industries; machining of these materials is gradually assuming a significant role. The current knowledge of machining FRP composites is in transition phase for its optimum economic utilization in various fields of applications. Therefore, material properties and theoretical mechanics have become the predominant research areas in this field. With increasing applications, economical techniques of production are indeed very important to achieve fully automated large-scale manufacturing cycles. Although FRP composites are usually molded, for obtaining close fits and tolerances and also achieving near-net shape, certain amount of machining has to be carried out. Due to their anisotropy, and non-homogeneity, FRP composites face considerable problems in machining like fibre pull-out, delamination, burning, etc. There is a remarkable difference between the machining of conventional metals and their alloys and that of composite materials. Further, each composite differs in its machining behavior since its physical and mechanical properties depend largely on the type of fibre, the fibre content, the fibre orientation and variabilities in the matrix material. Considerable amount of literature is readily available on the machinability of conventional metals/alloys and also polymers to some extent; with very limited work on FRP composites. Therefore, machining process optimization for all types FRP composites is still an emerging area of research. In this context, the present research highlights a multi-objective extended optimization methodology to be applied in machining FRP-polyester/epoxy composites with contradicting requirements of quality as well as productivity. Attempt has been made to develop a robust methodology for multi-response optimization in FRP composite machining 6 for continuous quality improvement and off-line quality control. Design of Experiment(DOE) has been be selected based on Taguchi’s orthogonal array design with varying process control parameters like: spindle speed, feed rate and depth of cut. Multiple surface roughness parameters of the machined FRP product along with Material Removal Rate (MRR) of the machining process have been optimized simultaneously. A Fuzzy Inference System (FIS) integrated with Taguchi’s philosophy has been proposed for providing feasible means for meaningful aggregation of multiple objective functions into an equivalent single performance index (MPCI). This Multi Performance Characteristic Index (MPCI) has been optimized finally. Detailed methodology of the proposed fuzzy based optimization approach has been illustrated in this reporting and validated by experiments

Studies on some aspects of composite machining

In this technological era, globalization has brought new challenges for the manufacturing industries, towards improving quality and productivity simultaneously, by reducing costs and increasing the performance of the machine tools. Process simulation is one of the most important aspects in any manufacturing/production context. With upcoming worldwide applications of Glass Fiber Reinforced Polymer (GFRP) composites; machining has become an important issue which needs to be investigated in detail. Process efficiency is measured in the sense of different objective functions or process output responses weather they are acceptable for a given targeted value or tolerance. Therefore, finding the best optimal parameter combination can lead towards improvement of the overall process efficiency. The performance of the process can be improved by applying optimization to the simulation model with respect to its process parameters. Single objective optimization method often creates conflict, when more than one response variables need to be optimized simultaneously. In order to minimize cost and to maximize production rate simultaneously; multi-objective optimization approach should be explored. In this thesis, multi-objective optimization methods have been reported to study some aspects of machining of composite material i.e. Glass Fiber Reinforced Polymer (GFRP) composite. The various process parameters used were cutting speed, feed rate, and depth of cut. Optimal cutting condition has been aimed to be evaluated to satisfy contradicting multi-requirements of product quality as well as productivity. This thesis has intended towards focusing two important aspects (i) when it comes to improve productivity, material removal rate has been considered and for (ii) quality of the machined composite product, various surface roughness characteristics of statistical importance have been investigated

Milling/routing of carbon fibre reinforced plastic (CFRP) composites

The research relates to a study on the routing/slotting of CFRP composites of the type used in aerospace applications. Following a literature review, 3 phases of experimental work were undertaken to evaluate the effects of key process variables on the machinability of CFRP. The influence of varying operating parameters, tool material and cutting environment were initially investigated in Phase 1 work. The results showed that use of PCD was critical and highlighted the importance of chilled air in maintaining adequate tool life and acceptable workpiece integrity. Delivery of chilled air through a single-nozzle arrangement generally led to an increase in forces and delamination with the twin-nozzle configuration showing superior workpiece surface roughness. Phase 2 work detailed the effect of workpiece lay-up configuration on cutting forces, temperature and surface integrity following slotting and routing. Plies in the 45 direction generally exhibited the highest level of surface damage following machining. Experiments in Phase 3 showed that relatively small helix angles (± 3) had a negligible effect on tool life, forces and temperature. In addition, cutters with a single relief angle were found to have lower stability in operation compared to tools with a secondary clearance angle, with detrimental effects on surface roughness

Etude de l'impact des défauts d'usinage des structures composites par détourage sur leur comportement mécanique

Ce travail, qui porte sur les problématiques de l'usinage par détourage des structures composites fibres longues, est composé de trois volets. Dans le premier volet, l'impact des paramètres de coupe, des procédés d'usinage et de la nature des matériaux composites sur la forme et la taille des défauts de surface est discuté. Le deuxième volet est dédié à la l'analyse des poussières générées lors de l'usinage. Le nombre et la masse des particules sont discutés en fonction de la géométrie des outils, des conditions de coupe et la nature du matériau composite usiné. Le dernier volet est consacré à l'étude de l'impact des défauts de surface et des procédés d'usinage sur le comportement mécanique (quasi- statique et dynamique).This thesis focuses on problems encountered during the trimming of composites materials using continuous fibers. The thesis is divided into three main parts. In the first part, the machinability of two composites materials made of carbon fiber and epoxy matrix at standard cutting speed and at high cutting speed is investigated. Surface damages induced are analyzed using surface roughness tester and the scanning electronic microscope. The impact of cutting conditions, machining processes (i.e., cutting tool, abrasive diamond cutter, abrasive water jet machining), and nature of composite materials on the form and size of the surface defects are studied. The second part of the thesis concerns the study of the dust generated during trimming in terms of number of particles present in air and masses. The effect of tool geometry, composite material and cutting conditions on the generated dust is studied. The last part is dedicated to the study of the relationship between machining processes, surface defects and mechanical behaviour of composite parts in quasi-static and dynamic environment. Specimens designed for quasi static tests are instrumented on the surface for the digital images correlations and high speed cameras to monitor the damage generation and progression during the tests. The dynamic tests are instrumented by an infrared camera in order to measure the thermal dissipation during the damaging phases of specimens

Modelos físicos y estadísticos para la caracterización del mecanizado de los materiales compuestos de matriz termoplástica

Doutoramento em Engenharia MecânicaA presente investigação tem como objectivos fundamentais estudar a maquinabilidade e definir modelos de corte para os materiais compósitos de matriz termoplástica. Foram efectuados ensaios de corte ortogonal e de torneamento sobre poliamidas PA 6 e PA 66 GF30 e sobre PEEK, PEEK CF30 e PEEK GF30. Encontram-se aplicações destes materiais, por exemplo, na indústria aeroespacial e aeronáutica, em biomecânica e elementos de construção de máquinas. Em grande parte destas aplicações é necessário obter superfícies com elevada qualidade o que exige operações de maquinagem. As poliamidas são materiais termoplásticos com aplicação corrente a nível industrial enquanto que as poli (éter-eter-cetonas) reforçadas são materiais compósitos avançados com enormes potencialidades no futuro. A maior parte das referências sobre a maquinagem de compósitos de matriz polimerica centram-se no estudo de materiais termoendureciveis logo os termoplásticos constituem um domínio interessante para investigação, tendo em conta o excelente conjunto de propriedades que exibem. O desenvolvimento experimental compreendeu os ensaios em corte ortogonal realizados com dois tipos de ferramentas, as pastilhas de carbonetos sinterizados (K10) e os insertos de diamante policristalino (PCD), e planos de ensaios específicos para verificar certos efeitos como a profundidade de corte ou o material e geometria da ferramenta. Durante o processo de torneamento registaram-se de um modo contínuo as forças de corte, o que permitiu em conjunto com a medição da espessura de apara definir o modelo físico de corte para estes materiais e estabelecer relações com o modelo teórico de Merchant. A medição da rugosidade permitiu também obter resultados para analisar a maquinabilidade destes materiais compósitos. Recorreu-se também a técnicas estatísticas nomeadamente à análise de variância, para estabelecer modelos de previsão e optimizar as condições de corte.La presente Tesis Doctoral tiene como objetivos fundamentales estudiar la maquinabilidad y definir los modelos de corte de los materiales compuestos de matriz polimérica termoplástica. Se han realizado ensayos de torneado sobre dos materiales pertenecientes a la familia de las poliamidas, en concreto la PA 6 y la PA 66-GF30, reforzada con 30% de fibras de vidrio, y sobre tres materiales pertenecientes a la familia de las poli (éter-éter-cetonas), el PEEK, el PEEK CF30, reforzado con 30% de fibras de carbono, y el PEEK GF30, reforzado con 30% de fibras de vidrio. Las aplicaciones más frecuentes de estos materiales son la industria aeroespacial, la biomecánica y la construcción de elementos de máquinas, principalmente. En buena parte de sus aplicaciones, es preciso conseguir superficies con un grado de calidad determinado, lo que exige realizar operaciones de mecanizado posteriores al conformado del material. Las poliamidas son materiales termoplásticos implantados a nivel industrial mientras que las poli (éter-éter-cetonas) reforzadas son materiales compuestos avanzados con enormes potencialidades de cara al futuro. La mayor parte de las referencias sobre el mecanizado de los materiales compuestos de matriz polimérica se centran en el estudio de los materiales termoestables, mientras que los termoplásticos constituyen un terreno abonado para la investigación, teniendo en cuenta el excelente conjunto de propiedades que exhiben. El desarrollo experimental comprende los ensayos de corte ortogonal, realizados con dos tipos de herramientas, las pastillas de carburos cementados (K10) y los insertos de diamante policristalino (PCD), y planes de ensayos específicos para verificar ciertos efectos como la influencia de la profundidad de pasada o la geometría de la herramienta. Durante el proceso de torneado se registran de manera continua las fuerzas de corte, lo que permitirá, junto con la medida del espesor de viruta, definir el modelo físico de corte de estos materiales y establecer relaciones con respecto al modelo teórico de Merchant. La medida de la rugosidad permitirá también obtener resultados para analizar la maquinabilidad de estos materiales compuestos. Se recurre a técnicas estadísticas, entre ellas el análisis de varianza, para completar el estudio del mecanizado, establecer modelos de predicción y, en todo caso, optimizar las condiciones de corte. Sobre la base de la experimentación y de los ulteriores análisis realizados, se pone de manifiesto el efecto de las fibras de refuerzo sobre la maquinabilidad de estos materiales compuestos, así como la influencia de la herramienta de corte en los resultados

High-Performance Eco-Efficient Concrete

This book is dedicated to “High-Performance Eco-Efficient Concrete” and concrete fatigue behavior, more sustainable construction materials, capable of complying with quality standards and current innovation policies, aimed at saving natural resources and reducing global pollution. The development of self-compacting concretes with electric arc furnace slags is a further achievement. In addition, the technical and economic viability of using coarse recycled aggregates from crushed concrete in shotcrete, enhanced quality and reduced on-site construction time are the basic features of prefabricated bridge elements and systems, biomass bottom ash as aluminosilicate precursor and phosphogypsum were discussed. On the other hand, basalt fiber improving the mechanical properties and durability of reactive powder concrete, alkali-activated slag and high-volume fly ash and the potential of phosphogypsum as secondary raw material in construction industry, the effects of fly ash on the diffusion, bonding, and microproperties of chloride penetration in concrete were studied. Increasing amounts of sustainable concretes are being used as society becomes more aware of the environment. Finally, the circular economy as an economic model of production and consumption that involves reusing, repairing, refurbishing, and recycling materials after their service life are presented in this book

Proceedings of the 2018 Canadian Society for Mechanical Engineering (CSME) International Congress

Published proceedings of the 2018 Canadian Society for Mechanical Engineering (CSME) International Congress, hosted by York University, 27-30 May 2018