EXPLORING STRUCTURAL DESIGN OF THE FRANCIS HYDRO-TURBINE BLADES USING COMPOSITE MATERIALS

Composite materials are increasingly exploited in industry especially replacing metallic structures due to their strength/weight ratio. Amongst the notable applications, for which composite materials have not challenged metals yet are hydro-turbines, which are overwhelmingly made of steel or copper alloys. Replacing blade material by laminate composites can reduce weight and inertia, as well as achieve smaller cross-sectional thicknesses, better fatigue strength, damping, and resistance to cavitation. Manufacturing techniques are mature enough to respond to the challenge, provided that the laminate composite blades are properly designed. In the current work, the design of the Francis carbon blades was studied by employing finite element analysis. The blades were designed sub-optimally with various stratification patterns and different failure and maximum displacement limitations following a systematic methodology for gradual addition of laminate layers or patches. The methodology is still of a trial and error nature driven by the designer but guesses in the individual steps are much more informed due to model analysis and optimization tools available

Internet of things and industrial applications for precision machining

The Internet of Things (IoT) can be regarded as an attempt to bring together the physical and the digital world by using devices for seamlessly exchanging and processing information that can be used anywhere, anytime. For industrial automation and manufacturing, the Industrial Internet of Things (IIoT) is regarded as the next step of industrial revolution that promises a step-change in productivity and operational efficiency. Precision machining is a field that has received a lot of research interest as it deals with phenomena and underlying mechanisms that are very complex and highly interacting. As the requirements and demand for products of high quality and tolerances that must be produced with shorter lead times are increasing, innovative approaches and methodologies need to be developed to compensate and IIoT offers an appropriate platform. This paper aims to present an overview of IIoT, investigate potential industrial applications for precision machining and predict future trends

Removed material volume calculations in CNC milling by exploiting CAD functionality

Material removal volume calculations in machining processes are important in a variety of milling simulation applications, including material removal rate estimation and machining force calculation. In this paper two different approaches are presented to this end, i.e., Z-maps and Boolean operations with solid models. The Z-map method is simple but results in large files and needs sophisticated routines to render acceptable accuracy. Boolean operations between accurate solid models of the tool and the workpiece is implemented on readily available CAD system application programming interface. Beside the computational load which is bound to the accuracy level, it requires a sufficient number of interpolated points through one revolution of the tool to be trustworthy. It is practical to use at particular points of interest along the toolpath

NUMERICAL SIMULATION OF SINGLE POINT INCREMENTAL FORMING FOR ASYMMETRIC PARTS

Single point incremental forming (SPIF) that will produce non-symmetric sheet metal parts has been rarely dealt with so far. SPIF of a Francis hydro-turbine vane made of aluminum alloy is studied as a typical example in this work. At first, a concave geometry, encompassing the desired vane shape is designed, from which the formed part will be ultimately cut out. The necessary SPIF toolpaths are created by using the CAM software normally used for milling processes. Based on these toolpaths, a finite element simulation is setup using shell elements with a particular emphasis on substantial time scaling and due care on tool-sheet contact parameters. For validation purposes the part was manufactured and digitized by a white light scanner. It exhibited tolerable deviation from the targeted nominal geometry. Simulation predicted a significant part of this deviation, proving its indispensability in checking out toolpaths and process parameters for non-symmetric parts, yet at non-negligible computational time

Removed material volume calculations in CNC milling by exploiting CAD functionality

Material removal volume calculations in machining processes are important in a variety of milling simulation applications, including material removal rate estimation and machining force calculation. In this paper two different approaches are presented to this end, i.e., Z-maps and Boolean operations with solid models. The Z-map method is simple but results in large files and needs sophisticated routines to render acceptable accuracy. Boolean operations between accurate solid models of the tool and the workpiece is implemented on readily available CAD system application programming interface. Beside the computational load which is bound to the accuracy level, it requires a sufficient number of interpolated points through one revolution of the tool to be trustworthy. It is practical to use at particular points of interest along the toolpath

REDESIGN AND TOPOLOGY OPTIMIZATION OF AN INDUSTRIAL ROBOT LINK FOR ADDITIVE MANUFACTURING

Design optimization for Additive Manufacturing is demonstrated by the example of an industrial robot link. The part is first redesigned so that its shape details are compatible with the requirements of the Selective Laser Sintering technique. Subsequently, the SIMP method of topology optimization is utilized on commercially available software in order to obtain the optimum design of the part with restrictions applicable to Additive Manufacturing, namely member thickness, symmetry and avoidance of cavities and undercuts. Mass and strain energy are the design responses. The volume was constrained by a fraction of the initial mass. The desired minimization of maximum strain energy is expressed as an objective function. A 7% reduction in the mass of the part was achieved while its strength and stiffness remained unchanged. The process is supported by topology optimization software but it also involves some trial-and-error depending on the designer’s experience

Removed material volume calculations in CNC milling by exploiting CAD functionality

Material removal volume calculations in machining processes are important in a variety of milling simulation applications, including material removal rate estimation and machining force calculation. In this paper two different approaches are presented to this end, i.e., Z-maps and Boolean operations with solid models. The Z-map method is simple but results in large files and needs sophisticated routines to render acceptable accuracy. Boolean operations between accurate solid models of the tool and the workpiece is implemented on readily available CAD system application programming interface. Beside the computational load which is bound to the accuracy level, it requires a sufficient number of interpolated points through one revolution of the tool to be trustworthy. It is practical to use at particular points of interest along the toolpath