Constantin Gheorghe Opran

• Emeritus; Habil.; PhD.; MSc.; Eng.
• Professor (Full) at Universitatea Națională de Știință și Tehnologie Politehnica București

This study focuses on the machinability of a novel eco-friendly biocomposite reinforced with 30 wt. % of treated date palm fibers (DPFs), designed to meet modern environmental requirements. This innovative material, fabricated through a combination of single-screw extrusion and compression molding, holds significant potential for applications in va...

Composite structures currently represent combinations of materials from the most different structures, chemical compositions, or geometric shapes. There is no scientific or technical field in which these materials, due to their special characteristic properties, are not present. Most of the time it is found that they cannot even be replaced. In thi...

This work presents the preparation process of composite from date palm fibers and Phenolic as a matrix by compression molding. The composites are prepared with a different weight fraction of fiber from 40 to 60 wt%. The enhancement of the mechanical properties is related to the good interaction and adhesion between the filler and the matrix which i...

Industrial automation refers to the control of machines and processes in order to manage variables. Automated manufacturing systems have evolved as advanced technologies have been incorporated, and theoretical approaches have evolved from mass production to intelligent manufacturing, each step introducing superior manufacturing concepts and models,...

The research aim is to investigate cellular structures inspired from nature, in order to improve the internal structural resistance of turbine system components (e.g. hydroelectric and gas turbine blades, OGV-Outer Guide Vanes, nacelles, gearboxes) with reduced mass. The investigations were conducted at laboratory level, utilizing two 3D printing t...

This paper deals with a Finite Element (FE) numerical analysis of an electromagnetic stirring system for composite plastic materials with ferromagnetic particles. The electromagnetic stirring process is ensured by the magnetic forces acting on the ferromagnetic particles spread in the plastic matrix. These forces are produced by the rotating magnet...

Drone noise remains one of the most important aspects, hindering their use in urban areas. Characterizing and minimizing it is the focus of this study. Although a preliminary Computational Fluid Dynamics study has been conducted, the bulk of the work presented is experimental. To that effect, a variation of the baseline propeller is put forth and t...

Over the recent years, many industries have been affected by serious accidents that have resulted in loss of human lives and caused major impacts on the environment, but also significant damage to corporates’ budget and reputation. To prevent such undesirable consequences, the international community has regulated safety risk management standards w...

The edge of manufacturing automation is considered the Lean Production System, who allows to reduce complexity, optimize resources, and eliminate waste in order to increase efficiency, flexibility, and profitability. By using advanced technologies, the production system and manufacturing processes can achieve an intelligent automation level, called...

When an autonomous industrial vehicle moves to a certain point to take over or leave an order, intermediate commands may appear on its route that can be taken together with the first order. Orders will be allocated through an algorithm that analyzes delivery times and priorities. This paper presents results of researches regarding the development a...

Composite materials are obtained by combining two or more materials with different physical properties, which maintain their properties at the macromolecular level, thus retaining their identity, to obtain a resulting material with characteristics clearly superior to the constituent elements, comparable to conventional materials in terms of perform...

The paper deals with the classification, applications, and advantages of microelectromechanical systems (MEMS), materials, and technologies used. This area of production represents one of the most promising technologies of 21st century, with a big impact in manufacturing 4.0. Nowadays, MEMS fabrication methods have a very big influence in the area...

Polymeric composites products are undeniable trends today, especially in the most innovative fields and with a permanent degree of novelty. The specialized literature presents a very wide range of their applications in the avant-garde fields such as the aerospace field and that of the automotive industry. Paper presents the results of research on m...

Hybrid joints are a wide diffused design solution in the manufacturing industry for mechanical parts connection. The simultaneous use of two different connection mechanisms, such as bonding and bolting, allows to exploit the advantages of both techniques. There are many industrial applications where such methodology is extensively used, such as the...

All components contribute to the total electrical resistance in the fuel cell including the bipolar plates (BP). Contact interface between BP and gas diffusion layers (GDL) can influence the voltage losses. It is usually assumed the real contact area of two metal surfaces is determined by the plastic deformation of their highest asperities. The con...

This long‐term study explores the development and application of a polymeric composite product with end goal to represent a light‐weight and eco‐friendly alternative to an existing car part, with current paper focusing on product development. Selecting the right constituents for an advanced polymeric composite product, having its end functional rol...

Composite products have now reached very important production volumes in many avant‐garde industries or always innovative industries such as automotive or aerospace. Composite products allow engineers to adjust the formulation to meet specific strength or temperature requirements of any application. In short by combining specific materials and adju...

Hybrid mechanical joints are achieved by the simultaneous use of multiple connection mechanisms such as bolting and bonding. This technique allows to obtain advantages in terms of mechanical properties compared to simple joints such as longer fatigue life and operability in critical environmental conditions. Many parameters influence the structural...

Failure mode and effects analysis (FMEA) is one of the most efficient and effective methods of preventing defects and other nonconformities, by assessing potential failure of component functions during the fabrication process, their causes and effects, with the purpose of identifying preventive actions which can have the consequence a higher produc...

In the polymer products industry, new technologies and Industry 4.0 concepts represent real solutions to increase efficiency and profitability through creating the intelligent and adaptable manufacturing system. At the same time, the existing manufacturing systems have made sustained efforts to implement Lean principles, techniques and tools to ach...

Most mechanical structures are composed of several components of different shape, size and material. In order to guarantee the connections among such parts is often necessary to adopt different connection mechanisms. The joints represent the structure possible weak points, can be easily site of damage and rupture so their careful design plays a dec...

Nature is an excellent source of inspiration. Understanding nature can lead to new discoveries of new materials, applications, products. Scientists have found out technologies that seek to mimic some of life's unique innovations. In Germany researchers have developed a synthetic shark skin made of elastic silicone that reduces bio‐fouling. Engineer...

Polymeric products design and manufacturing is a complex industrial process that combines elements of chemical composition of plastics with injection modeling technology designed to optimize economic and technical parameters. A number of risks can disrupt the proper execution of the works and consequently alter the technical and economic objectives...

The delamination process is the main cause of the process of destruction of composite materials and of any technological process of deposition of different layers. This paper presents finite elements modeling of this type of multi‐layer structure failure from a practice experiment. It is thus attempted to create a mathematical model able to predict...

Resin Transfer Molding process (RTM), is the most used technology to create large parts made by polymer matrix composites because: the production time is relative small; the consumption of materials is reduced to minimum; the obtained parts are in a constant tolerance of ±0.5 mm after de‐molding; both sides of the part are shiny and smooth; determi...

In the polymeric products industry, the lean production system is perceived as a solution to reduce difficulties of manufacturing automation processes complexity while reducing used resources, eliminate losses, and increase efficiency, flexibility, and profitability. Industry 4.0 is the stage of intelligent automation that exploits the latest devel...

Composite materials are increasingly used in those fields where it is necessary to achieve the requirements of lightweight and high mechanical properties. Even though their high specific strength which get these materials very attractive, especially for the transport field, there are several critical issues that still limit their application in pri...

Hydrogen and fuel cell technologies were identified amongst new renewable energy technologies which contribute strongly to mitigating climate change. Important research activities were directed to the injection molded bipolar plates made by conductive polymeric composites. The mold surface quality can help obtaining better conductivity. In this pap...

This paper presents the current state of the conception of a magnetic drive micropump, different necessary constructive-technological and functional considerations, 3D modeling using parametric design, main geometric elements of the gears with helical teeth, specific calculations needed to determine the forces loads on the gears and a printed proto...

Fiber-reinforced composite materials are increasingly present in areas such as automotive, aeronautics, defense, sport, used due to their special mechanical characteristics and very good behavior under heavy working conditions. New mold design techniques (such as 3D printing technologies), processing (such as the use of robotic technologies), open...

Engineering Science Based on Modelling and Simulation (M & S) is defined as the discipline that provides the scientific and mathematical basis for simulation of engineering systems. These systems range from microelectronic devices to automobiles, aircraft, and even oilfield and city infrastructure. In a word, M & S combines knowledge and techniques...

The oxygen diffusion is a natural phenomenon and a main factor during the atmospheric corrosion process. The phenomenon of oxygen diffusion takes place in the environment with different consequences: vital in medicine in relation with the oxygen diffusion in the blood, or negative in technical or industrial domains with catastrophic consequences du...

Fuel cells are electrochemical devices that convert chemical energy of fuels into electrical energy. Fuel cells were used in NASA space programs to generate energy to satellites and space capsules. Today fuel cells are used to power vehicles including automobiles, forklifts, buses, boats, motorcycles or submarines. Bipolar plates are components of...

In the medical industry the medical device sector is a domain dynamic and growing, that involved important efforts performance for imposing new material to support the development of new products. Manufacturers of medical devices for single use, are constantly looking for new products and new materials to expand their capabilities.

The demand for conductive fuel cell stack components contributed to the research and development of composite materials and technologies. Significant activities were directed to the study of low-cost bipolar plates made in thermosets and thermoplastics manufactured by compression and injection molding. For the production of conductive thermoplastic...

Biodegradable polymers became one of the most important materials with large applicability, as they do not generate wastes after life cycle. An important application is food packaging fabricated by injection molding processing. In this paper, we present the investigation of the mechanical properties of some biodegradable polymers based on PLA compo...

This paper presents an overview of an improved solution for an existing micropump model and, also, of the materials recommended to be used in the current stage of the prototype research. This micropump is provided with a closed system for driving and pumping the fluid, obtained by a special constructive solution, where the rotation of the motor sha...

Injection moulding is one of the most commonly used manufacturing processes for composite polymeric products, with high challenges. Dimensional accuracy, optimal mechanical-physical properties as well as very good aesthetic of the polymeric products are requiring a precise controlled injection moulding system. The mould precision influences the pro...

This paper deals with the development of a numerical model, based on the Finite Element Method (FEM), for the simulation of Low Velocity Impact (LVI) phenomena on short Glass Fibre Reinforced Polymers (GFRP) plates with two different impact energy levels. In order to assess the reliability of the proposed FE model, the numerical results have been c...

This paper presents preliminary research results on innovative and adaptive redesign of a magnetic drive micropump with helical gears. We have illustrated some issues of a gears micropump and particularly its worn components caused by the running process in its hydraulic installation. The design procedure and all the ideas involved in the research...

In this paper we report the investigation of optical properties of As2S3 amorphous chalcogenide thin films. Arsenic trisulfide is well known amorphous material. As2S3 thin films have important applications in optoelectronics. The most usual method of fabrication is thermal evaporation in vacuum which is known for deposition ofa-As2S3 films with hig...

This paper presents some of the research results on a fundamental and applicative procedures regarding the integrated intelligent conception of a Romanian series of hydraulic gear pumps. Following the analysis of the pump series in the manufacturing process, the requirement for a modernized parametric design of this product has been identified. Thu...

Aim of this research is the structural analysis by comparison of the biodegradable properties of two polymeric products made by non-biodegradable polymeric material (polypropylene TIPPLEN H949 A) and biodegradable polymeric material (ECOVIO IS 1335), under microorganism activity in order to give the best solution for the manufacture of food packagi...

The paper presents the current stage of constructive-technological and functional researches on magnetic drive pumps. This type of pump is provided with a closed system for driving and pumping the fluid. It is envisaged that the rotation of the motor shaft is done by induction of a magnetic field without external drive from an electric motor, as in...

Polymeric bio-composites have special characteristics and use in various areas such as: automotive, aviation and aeronautic industries, civil engineering and for medical devices manufacturing. This paper presents the evaluation of impact behaviour of some types of materials suitable for orthopaedic use. As composites behave very differently at diff...

Natural phenomena can be modelled adequately precise with differential equations. An example of such phenomena is diffusion. All differential equations with partial derivatives, of two variables and of the second order, which model the diffusion are parabolic with simple solutions. This simple solution is: erf(x), exponential functions or power ser...

This paper presents the results of the researches with application in production for the innovative realization of the double gear pumps with minimum axial gauge and minimum number of parts for the increase of reliability in use and reducing the production costs. The innovative design characteristic is represented by adaptive dimensioning with mini...

This paper reviews experimental research regarding brittle materials processing with superfinishing machine The main criteria for determining the characteristics of superfinishing machines can be grouped into: energy consumption criterion, technologically criterion and dynamic criterion can be determined and the main criteria optimization plan lapp...

This paper present the results of the researches regarding innovative and adaptive design of gear pumps for engineering of polymeric products with application in production of injection molding machine. It shows the description of gear pump with innovative design and double gear pump – innovative design, highlighting innovative design feature throu...

Paper presents ultrasonic system design and calculation for metallization process of the polymer pieces. Because of some bad properties like: very low hardness, very low wear resistance, no electrical conductivity and no open fire resistance, polymer parts has to be reinforced with different materials. A new method is represented by ultrasonic fiel...

The paper presents the parameter influence on the process of pressing aids in reinforced thermosetting polymer mold blanks Sheet Moulding Compound type (SMC) used to obtain large pieces of automotive bodywork. In the first part of the paper presents complex recipe constitutive factors of R-SMC prepreg, analyzing and choosing the optimal tehnnology...

This paper present the results of the researches regarding innovative design of polymeric systems used in manufacturing of gear pumps with application to reversible pumps used both as pumps as well as motors or steps of the flow dividers. It shows the description of reversible gear pump, with compensating seal in the innovative variant and compensa...

The paper deals with phenomena occurring at the ultrasonic aided electrical discharge machining (EDM-US) of electro-conductive metal matrix composites materials (EC-MMCs-Al/Al2O3p). Starting from the analysis of the cavitational phenomena due to the forced ultrasonic longitudinal vibrations of the electrode and the phenomena caused by the thermal s...

The paper presents the development of a scientific cloud computing community for polymeric and composites products that offers high performance computation capability. The scientific research community will use the cloud to resolve complex issues. This community will include data storage, a polymeric materials encyclopaedia, softwares for simulatio...

The diffusion phenomenon is widely spread in nature and bears a special importance for corrosion. Corrosion can have an impact on equipment and installation safety, from simple steel objects to nuclear reactors. As a result, it is extremely important to study corrosion and, indirectly, the phenomenon that sustains it, namely oxygen diffusion. The c...

Glass fibers reinforced sandwich polymeric composites represent a new materials widely used in various industrial fields, due to their special characteristics. This paper presents the results of experimental research carried out on sandwich polymeric composites reinforced with fiberglass - especially used in automotive industry. © 2014, Academic As...

Micro injection molding is a domain which implies challenges for both producers of moulds and technologists. Due to special conditions required by the process of micro injection molding, chemical, physical and thermal properties of the injected polymeric material are affected, material behaviour is different compared with that during the classical...

3D computer graphic artists have focused more on animated films, broadcast, feature films, interactive video games, visual effects and web. Especially for industrial and technical design, rendering process is not given due attention. This paper presents a way to achieve realistic images in the technical field. Creating quality images in CAD program...

The diffusion phenomenon is widely spread in nature and bears a special importance for corrosion. Corrosion can have an impact on equipment and installation safety, from simple steel objects to nuclear reactors. As a result, it is extremely important to study corrosion and, indirectly, the phenomenon that sustains it, namely oxygen diffusion. The c...

This paper presents the adaptive control of the temperature in the injection mold using additive manufacturing in order to achieve the controlled and specific cooling channels in the components parts of the injection molds of polymeric products. The increasing complexity of technical characteristics by construction and technology of the polymer pro...

Numerical simulation results obtained in investigating laser paint removal from different metal substrates, mainly aluminum and aluminum alloys, are presented. The main purpose of the developed simulation model is to define the laser installation specifications required for an operation that does not affect the substrate on which the paint is depos...

The main purpose of the paper consists of presenting simulation results obtained in analyzing the surface plasmons excitation effect, presently commonly referred as surface plasmon resonance (SPR) and its main possible application as a highly accurate and sensitive sensor. Both electromagnetic wave coupling configurations to the medium, grating and...

The preliminary numerical simulation results obtained in the analysis of a landmine detection system based on laser excitation of acoustic - seismic waves in the soil and observing its surface vibration above the embedded landmine are presented. The presented numerical simulations comprise three main parts: 1) Laser oscillator and laser beam propag...

The sandwich composite polymeric products have a wide utilization in various fileds like aircraft and automotive construction, load bearing structures, sports equipment, more specifically, wherever weight-saving is required. Sandwich composites polymeric products represent excellent examples of the potential offered by composite materials. The comb...

Subsurface damage evaluation is performed using a combination of scanning electron microscopy and damage inspection techniques on silicon nitride and silicon carbide ground by single point diamond tools and diamond wheels. Two forms of surface damage are indentified, material pulverization in the superficial layer forming o powder regime and void g...

For scientific research and industrial application it is important to determine mathematical models of force and torque, when machining. Thus, is would be possible to know optimum process parameters values or even better, to predict force and torque values, once process parameters values set. Drilling in polymeric biocomposites is required in many...

The heat released in the drilling process is generating by the mechanical work, separation and removal of chips from the machining area, and also to overcome the friction between chip, tool and surface rake. The heat resulted during the drilling process, travels from the source to the cold areas, distributing in the drilling tool, chip, perform and...

During the wafer polishing operation a number of dynamic forces are in operation that may affect overall pad life and removal rates. In an effort to examine some of these forces and attempt to gain a better understanding of them, a model has been developed and is presented here in the spirit of experimentation.

In this paper are presented the effect of some liquids of general use upon the shape and structure of the monthly worn contact lenses used for visual comfort. A split lamp was used to observe the position and adjustment on the subject corneal surface of the contact lenses for visual comfort and physiological acceptance.

The Energy represent a necessity in a modern society. To meet the needs of food, environment, housing, lighting, transport and freight and goods requires, information technology, is necessary to supply of good energy. Energy sector affects the evolution of whole societies. Currently conceived cannot be a developed economy, with an adequate social s...

This paper presents the evaluation of impact behaviour on different used polymeric materials. The Charpy impact test could be with or without V-notch, and is a standardized strain rate test which determines the amount of energy absorbed by a material during fracture. This absorbed energy is a measure of a given material's toughness and acts as a to...

Polymeric composite sandwich structures have a wide utilization of the domain activities in which the behaviors at impact represent the main parameter in using the capability. Such as is necessary to know and make the shaping and simulation for behavior at impact in structures. This paper contains the shaping and simulation at impact of polymeric c...

In order to obtain a suitable rigid implant, we need to be certain that its properties are very close to the structure it is supposed to replace or support. For this reason, the materials to be used for manufacturing should be carefully selected, so that their mechanical and biomechanical properties correspond to the intended purpose. The present p...

The paper presents a new testing stand for antifriction bearings, suitable for all types of rolling and sliding bearings, especially for those having small diameters and operating at high rotation speeds. The design of this stand occurred as a necessity of additional equipment to the research endowment required by several research projects develope...

Composite ceramics materials have known an increasing development, because of their important characteristics and advantages. Among them, an important role is that of electro-conductive structural ceramics composites - CCsEc-Al2O3/TiC. In order to obtain a part with specified shape and dimensions, made of this material type, most of the times a mas...

Advances at the plastics manufacturing level in suc h areas as co-extrusion and the production of specialty polymers and additives, res ult in the availability of plastics with improved characteristics. We have produced an agricultural p hoto-selective three layer co-extrusion film, manufactured at a thickness of about 200 μm. The film was made fro...

Plasticulture is a system of growingcrops in a way so that a significant benefit is derived from using plastic polymers. We have obtained a threeyer polymeric foil with photoselective additives in order to modificate the microclimate. This foil was subjected to an experiment by covering high tunnels with tobacco culture. We have reported about opti...

In order to facilitate a new approach through the philosophy of life-cycle engineering management, the paper proposes an unitary methodology under the name Functional-Technological Engineering (FTE). FTE takes into account both functional and technological aspects as determinative ones for the whole life-cycle evolution of a product. The methodolog...

The design process has already established successive stages with included steps taking considerations functional aspects and technological aspects. The design process is often separated into product design and technology design because of great differences of the life-cycle stages they are referring on. In fact, the two processes cannot be separat...

This paper deals with the electro-chemical machining in a medium with imposed magnetic field. It contains the analitical model of magnetic field distribution from working gap, the influence of magnetic field on electric and hydrodynamic parameters,as well as the influence on the productivity and the machining accuracy.

This paper presents a new mathematical model for the establishment of the partial and global machinability. The model, is based on the evaluation criteria of the material's machinability and permits the establishment of the best material, who can be utilised from the point of view of the machinability. Also, it permits the establishment of the mach...

In the work, the Mathematical model and the results of the experimental researches performed, are shown, in order to establish the partial and global tool cutting capacities. They enable the most adequate tools to be chosen, according to the imposed requirements. At the same time, the best cutting conditions can be chosen depending on the concrete...

The present Paper deals with the phenomena that appear in E.D.N. using the introduction of the tool-electrode having forced vibration coupled with the vibration of the technological machining system. A mathematical model confirmed by experimental research, is proposed for the tool-electrode motion and for the machining itself. There are also presen...

In this paper the analysis of introducing magnetic field in electrochemical machining is presented. As a result of our theoretical researches, the mathematical model for the machining of the workpiece and for the influence of the introduced magnetic field on the main parameters of the machining have been established

The electromechanical processing of holes made necessary the development of new technologies. The paper presents the theoretical and experimental researches, regarding the most important implications of the electrochemical microboring with a capillary electrode made of glass, with or without an metallic inner electrode. These are studied some physi...

Milling and drilling are the two machining operations most frequently involved in manufacturing parts made of fiber reinforced polymeric. Composites-specific quality criteria must know in order to asses the machining results. This paper presents a model for the prediction in machining operations of composite materials. The concept of chip is used t...