scholarly journals Hybrid Metal/Composite Lattice Structures: Design for Additive Manufacturing

Aerospace ◽  
2019 ◽  
Vol 6 (6) ◽  
pp. 71 ◽  
Author(s):  
Francesco Di Caprio ◽  
Valerio Acanfora ◽  
Stefania Franchitti ◽  
Andrea Sellitto ◽  
Aniello Riccio
Keyword(s):  
Numerical Procedure ◽  
Optimization Procedure ◽  
Metal Structure ◽  
Automatic Generation ◽  
Geometrical Model ◽  
Filament Winding ◽  
Metal Composite ◽  
Unit Cells ◽  
Numerical Tool ◽  
Definition Of

This paper introduces a numerical tool developed for the design and optimization of axial-symmetrical hybrid composite/metal structures. It is assumed that the defined structures are produced by means of two different processes: Additive Layer Manufacturing (ALM) for the metallic parts and Filament Winding (FW) for the composite parts. The defined optimization procedure involves two specific software: ANSYS and ModeFrontier. The former is dedicated to the production of the geometrical and FE models, to the structural analysis, and to the post-process, focusing on the definition of the Unit Cells for the modelling of the metal part. The latter is dedicated to the definition of the best design set and thus to the optimization flow management. The core of the developed numerical procedure is the routine based on the Ansys Parametric Design Language (APDL), which allows an automatic generation of any geometrical model defined by a generic design set. The developed procedure is able to choose the best design, in terms of structural performance, changing the lattice metallic parameters (number of unit cells and their topology) and the composite parameters (number of plies and their orientation). The introduced numerical tool has been used to design several hybrid structures configurations. These configurations have been analysed in terms of mechanical behaviour under specific boundary conditions and compared to similar conventional metal structure.

Consistency Management in Feature-Based Parametric Design

1995 ◽  
Author(s):  
Ana Sofia Vieira
Keyword(s):  
Parametric Design ◽  
Automatic Generation ◽  
Fundamental Principle ◽  
Consistency Management ◽  
Semantic Constraints ◽  
Evaluation Time ◽  
Feature Based ◽  
Consistent Feature ◽  
Semantic Correctness ◽  
Definition Of

Abstract One of the main problems to be solved in design-by-features is to preserve the semantic correctness of feature-based models. Currently, feature-based parametric design (FbPD) is being used as one of the most powerful approaches for solving this problem. In this paper, a fundamental principle of this approach is introduced. Three aspects stated, are: FbPD deals with functional design primitives, it solves the automatic generation of model variations, and it offers the basis for the development of a mechanism to check the semantic correctness of feature-based models. Several concepts for the definition of semantic constraints are presented. They instigate the classification of semantic constraints in four different categories, based on the constraint evaluation-time, purpose, behaviour, and representation. Sinfonia, a system for feature-based parametric design, is presented as a testbed environment for design-by-features applications. One of its modules, the Consistency Handler, uses the constraint concepts introduced in order to preserve the semantic consistency of the models. Several examples illustrate the different types of constraints. In addition, an algorithm applied for the process of a consistent feature modification is presented.

scholarly journals Generating Collaborative Systems for Digital Libraries: a Model-Driven Approach

2010 ◽  
Vol 29 (4) ◽  
pp. 171 ◽  
Author(s):  
Alessio Malizia ◽  
Paolo Bottoni ◽  
S. Levialdi
Keyword(s):  
Digital Library ◽  
User Interfaces ◽  
Digital Libraries ◽  
Automatic Generation ◽  
Visual Language ◽  
Domain Experts ◽  
Model Driven ◽  
Neutral Models ◽  
Definition Of ◽  
High Level

The design and development of a digital library involves different stakeholders, such as: information architects, librarians, and domain experts, who need to agree on a common language to describe, discuss, and negotiate the services the library has to offer. To this end, high-level, language-neutral models have to be devised. Metamodeling techniques favor the definition of domainspecific visual languages through which stakeholders can share their views and directly manipulate representations of the domain entities. This paper describes CRADLE (Cooperative-Relational Approach to Digital Library Environments), a metamodel-based framework and visual language for the definition of notions and services related to the development of digital libraries. A collection of tools allows the automatic generation of several services, defined with the CRADLE visual language, and of the graphical user interfaces providing access to them for the final user. The effectiveness of the approach is illustrated by presenting digital libraries generated with CRADLE, while the CRADLE environment has been evaluated by using the cognitive dimensions framework.

Arrangement and Optimisation Turbocompressors in an Off-Shore Natural Gas Extraction Station

2005 ◽  
Author(s):  
M. Pinelli ◽  
A. Mazzi ◽  
G. Russo
Keyword(s):  
Centrifugal Compressor ◽  
Gas Turbines ◽  
Optimization Procedure ◽  
Thermodynamic Cycle ◽  
Actual Operating ◽  
Gas Compression ◽  
Consequent Reduction ◽  
Suitable Arrangement ◽  
High Production ◽  
Definition Of

In this paper, a methodology for the optimization of a single off-shore gas compression station is developed. The station is composed of three gas turbines, each one driving a centrifugal compressor. The study concerns the feasibility of the most suitable arrangement to face the depletion of wells and the consequent reduction of the head top pressure. Once the arrangement is chosen, an optimization procedure is developed and carried out. The procedure, which is aimed at obtaining either high production rates or good station efficiency, is based on knowledge of the centrifugal compressor characteristics and on the availability of gas turbine thermodynamic cycle program, the latter allowing the definition of the machine actual operating state.

Aeroelastic Optimization of an Industrial Compressor Rotor Blade Geometry

2018 ◽  
Author(s):  
Federico Vanti ◽  
Lorenzo Pinelli ◽  
Andrea Arnone ◽  
Andrea Schneider ◽  
Pio Astrua ◽  
...  
Keyword(s):  
Numerical Procedure ◽  
Optimization Procedure ◽  
Multidisciplinary Optimization ◽  
Optimization Process ◽  
Geometrical Parameters ◽  
Aerodynamic Optimization ◽  
Compressor Rotor ◽  
Wide Range ◽  
Automatic Optimization ◽  
Blade Geometry

This paper describes a multidisciplinary optimization procedure applied to a compressor blade-row. The numerical procedure takes into account both aerodynamic (efficiency) and aeromechanic (flutter-free design) goals nowadays required by turbo-machinery industries and is applied to a low pressure compressor rotor geometry provided by Ansaldo Energia S.p.A.. Some typical geometrical parameters have been selected and modified during the automatic optimization process in order to generate an optimum geometry with an improved efficiency and, at the same time, a safety flutter margin. This new automatic optimization procedure, which now includes a flutter stability assessment, is an extension of an existing aerodynamic optimization process, which randomly perturbs a starting 3D blade geometry inside a constrained range of values, build the fluid mesh and run the CFD steady analysis. The new implementation provides the self-building of the solid mesh, the FEM analysis and finally the unsteady uncoupled aeroelastic analysis to assess the flutter occurrence. After simulating a wide range of geometries, a database with all the constraint parameters and objective functions is obtained and then used to train a neural network algorithm. Once the ANN validation error is converged, an optimization strategy is used to build the Pareto front and to provide a set of optimum geometries redesigning the original compressor rotor. The aim of this paper is to show the opportunity to also take into account the aeroelastic issues in optimization processes.

scholarly journals MEMS mirrors using sub-wavelength High- Contrast-Gratings with asymmetric unit cells

2016 ◽  
Vol 19 (2) ◽  
pp. 52
Author(s):  
Milan Maksimović
Keyword(s):  
Spectral Response ◽  
Practical Interest ◽  
Optimization Procedure ◽  
Material Design ◽  
Unit Cell ◽  
High Contrast ◽  
Asymmetric Unit ◽  
Unit Cells ◽  
Thin Elements ◽  
Sub Wavelength

High-contrast gratings (HCG) are ultra-thin elements operating in sub-wavelength regime with the period of the grating smaller than the wavelength and with the high-index grating material fully surrounded by low-index material. Design of MEMS mirrors made from HCG with specific reflectivity response is of great practical interest in integrated optoelectronics. We theoretically investigate design of the spectral response for HCGs with the complex unit cells. We show that the spectral response can be tailored via the unit cell perturbations and with the asymmetric unit cell perturbations may introduce completely new spectral response. Our results can serve as guidance for the design of the complex HCGs and help with the choice of the efficient initial grating topology prior to global optimization procedure.

scholarly journals Optimization of Ni-Based WC/Co/Cr Composite Coatings Produced by Multilayer Laser Cladding

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Andrea Angelastro ◽  
Sabina L. Campanelli ◽  
Giuseppe Casalino ◽  
Antonio D. Ludovico
Keyword(s):  
Laser Cladding ◽  
Steel Substrate ◽  
Composite Coatings ◽  
Metallic Matrix ◽  
Optimization Procedure ◽  
High Hardness ◽  
Fatigue Properties ◽  
Metal Composite ◽  
Tungsten Carbides ◽  
Cobalt Chromium

As a surface coating technique, laser cladding (LC) has been developed for improving wear, corrosion, and fatigue properties of mechanical components. The main advantage of this process is the capability of introducing hard particles such as SiC, TiC, and WC as reinforcements in the metallic matrix such as Ni-based alloy, Co-based alloy, and Fe-based alloy to form ceramic-metal composite coatings, which have very high hardness and good wear resistance. In this paper, Ni-based alloy (Colmonoy 227-F) and Tungsten Carbides/Cobalt/Chromium (WC/Co/Cr) composite coatings were fabricated by the multilayer laser cladding technique (MLC). An optimization procedure was implemented to obtain the combination of process parameters that minimizes the porosity and produces good adhesion to a stainless steel substrate. The optimization procedure was worked out with a mathematical model that was supported by an experimental analysis, which studied the shape of the clad track generated by melting coaxially fed powders with a laser. Microstructural and microhardness analysis completed the set of test performed on the coatings.

An Optimization Procedure of Model’s Base Construction in Multimodel Representation of Complex Nonlinear Systems

2021 ◽  
Author(s):  
Bennasr Hichem ◽  
M’Sahli Faouzi
Keyword(s):  
Nonlinear Systems ◽  
Learning Algorithm ◽  
Batch Reactor ◽  
Optimization Procedure ◽  
Base Number ◽  
Deterministic Approach ◽  
Modeling Analysis ◽  
Complex Nonlinear Systems ◽  
Definition Of ◽  
And Control

The multimodel approach is a research subject developed for modeling, analysis and control of complex systems. This approach supposes the definition of a set of simple models forming a model’s library. The number of models and the contribution of their validities is the main issues to consider in the multimodel approach. In this chapter, a new theoretical technique has been developed for this purpose based on a combination of probabilistic approaches with different objective function. First, the number of model is constructed using neural network and fuzzy logic. Indeed, the number of models is determined using frequency-sensitive competitive learning algorithm (FSCL) and the operating clusters are identified using Fuzzy K- means algorithm. Second, the Models’ base number is reduced. Focusing on the use of both two type of validity calculation for each model and a stochastic SVD technique is used to evaluate their contribution and permits the reduction of the Models’ base number. The combination of FSCL algorithms, K-means and the SVD technique for the proposed concept is considered as a deterministic approach discussed in this chapter has the potential to be applied to complex nonlinear systems with dynamic rapid. The recommended approach is implemented, reviewed and compared to academic benchmark and semi-batch reactor, the results in Models’ base reduction is very important witch gives a good performance in modeling.

Assessment and Optimization of the Aerodynamic and Acoustic Characteristics of a Counter Rotating Open Rotor

2012 ◽  
Vol 134 (6) ◽  
Author(s):  
R. Schnell ◽  
J. Yin ◽  
C. Voss ◽  
E. Nicke
Keyword(s):  
Optimization Procedure ◽  
Operating Conditions ◽  
Far Field ◽  
Multi Objective Optimization ◽  
Automatic Optimization ◽  
Open Rotor ◽  
Acoustic Evaluation ◽  
Definition Of ◽  
Cfd Method ◽  
The Given

The present study demonstrates the aerodynamic and acoustic optimization potential of a counter rotating open rotor. The objective was to maximize the propeller efficiency at top of climb conditions and to minimize the noise emission at takeoff while fulfilling the given thrust specifications at two operating conditions (takeoff and top of climb) considered. Both objectives were successfully met by applying an efficient multi-objective optimization procedure in combination with a 3D RANS method. The acoustic evaluation was carried out with a coupled U-RANS and an analytic far field prediction method based on an integral Ffowcs Williams-Hawkings approach. This first part of the paper deals with the application of DLR’s CFD method TRACE to counter rotating open rotors. This study features the choice and placement of boundary conditions, resolution requirements, and a corresponding meshing strategy. The aerodynamic performance in terms of thrust, torque, and efficiency was evaluated based on steady state calculations with a mixing plane placed in between both rotors, which allowed for an efficient and reliable evaluation of the performance, in particular, within the automatic optimization. The aerodynamic optimization was carried by the application of AutoOpti, a multi-objective optimization procedure based on an evolutionary algorithm, which also was developed at the Institute of propulsion technology at DLR. The optimization presented in this paper features more than 1600 converged 3D steady-state CFD simulations at two operating conditions, takeoff and top of climb, respectively. In order to accelerate the optimization process, a surrogate model based on a Kriging interpolation on the response surfaces was introduced. The main constrains and regions of interest during the optimization were a given power split between the rotors at takeoff, retaining an axial outflow at the aft rotor exit at top of climb, and fulfilling the given thrust specifications at both operating conditions. Two objectives were defined: One was to maximize the (propeller) efficiency at top of climb conditions. The other objective was an acoustic criteria aiming at decreasing the rotor/rotor interaction noise at takeoff by smoothening the front rotor wakes. Approximately 100 geometric parameters were set free during the optimization to allow for a flexible definition of the 3D blade geometry in terms of rotor sweep, aft rotor clipping, hub contour as well as a flexible definition of different 2D profiles at different radial locations. The acoustic evaluation was carried out based on unsteady 3D-RANS computations with the same CFD method (TRACE) involving an efficient single-passage phase-lag approach. These unsteady results were coupled with the integral Ffowcs Williams-Hawkings method APSIM via a permeable control surface covering both rotors. The far field directivities and spectra for a linear microphone array were evaluated, here mainly at the takeoff certification point. This (still time consuming) acoustic evaluation was carried out after the automatic optimization for a few of the most promising individuals only, and results will be presented in comparison with the baseline configuration. This detailed acoustic evaluation also allowed for an assessment of the effectiveness of the acoustic cost function as introduced within the automatic optimization.

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