Morphing Airfoil Design via L-System Generated Topology Optimization

2019 ◽  
Author(s):  
Madalyn Mikkelsen ◽  
Michayal Mathew ◽  
Patrick Walgren ◽  
Brent Bielefeldt ◽  
Pedro B. C. Leal ◽  
...  
Keyword(s):  
Structural Integrity ◽  
Aerodynamic Performance ◽  
Operating Conditions ◽  
Structural Topology ◽  
High Lift ◽  
L System ◽  
Design Variables ◽  
Weakly Coupled ◽  
System L ◽  
Internal Configuration

Abstract Morphing airfoils present an effective approach to managing the different requirements in each segment of a mission profile (e.g., takeoff/landing, cruise, and active maneuvering). In this work, an approach to morphing airfoil design that couples aerodynamic performance and internal structural configuration is detailed. The internal structural topology is formulated using a Lindenmayer System (L-System) coupled with a graph-based interpreter known as Spatial Interpretation for Development of Reconfigurable Structures (SPIDRS). The L-System encodes design variables that are interpreted via SPIDRS graphical operations and governs the development of the internal configuration (composed of elastic structural members and actuators). The global optimization uses a weakly coupled fluid-structure interaction (FSI) scheme for a first-order estimation of the aeroelastic loads that are critical for airfoil aerodynamic performance and structural integrity. Each airfoil is evaluated in two states: a standard non-actuated state to determine performance in standard operating conditions (e.g., cruise) and a high lift state, where internal shape memory alloy actuators are deformed to create a high lift configuration for the airfoil (e.g., takeoff/landing). Evaluating the aerodynamic performance of airfoils in these two states results in a series of potential solutions that best manage the tradeoff between aerodynamic metrics for both evaluated cases.

Graph-Based Interpretation of L-System Encodings Toward Aeroelastic Topology Optimization of a Morphing Airfoil in Supersonic Flow

2019 ◽  
Author(s):  
Brent R. Bielefeldt ◽  
Darren J. Hartl ◽  
Joshua D. Hodson ◽  
Gregory W. Reich ◽  
Philip S. Beran ◽  
...  
Keyword(s):  
Supersonic Flow ◽  
Performance Criteria ◽  
Preliminary Design ◽  
Structural Topology ◽  
L System ◽  
Design Variables ◽  
System L ◽  
Interpretation Algorithm ◽  
Actuation Systems ◽  
Reconfigurable Structures

Abstract This work details the preliminary design of a morphing airfoil in supersonic flow using evolutionary design principles. The structural topology of the airfoil includes a fixed outer mold line, fixed spars, and designable internal stiffeners and actuators. The designable components are generated using a bio-inspired model known as a Lindenmayer System (L-System), which encodes design variables and governs the development of a structural topology when coupled with an interpretation algorithm. Here, we utilize a graph-based interpretation scheme known as Spatial Interpretation for the Development of Reconfigurable Structures (SPIDRS), which has been shown to effectively explore the mechanism design space using a limited number of design variables. The optimization process behind this preliminary design problem is discussed, and optimal airfoil topologies capable of meeting specified aerodynamic performance criteria are presented in hopes of gaining a better understanding of how actuation systems could be integrated into the next generation of aircraft.

Evaluation of the Structural Integrity of Bell-Spigot Joints in Steel Gas Pipelines

2021 ◽  
Author(s):  
Freddy Alvarez ◽  
Heriberto Maury ◽  
Jorge Bris ◽  
Ricardo Lizarazo ◽  
Julio A. Medina S. ◽  
...  
Keyword(s):  
Structural Integrity ◽  
Operating Conditions ◽  
Gas Pipelines ◽  
Steel Pipes ◽  
Test Pieces ◽  
Pull Out ◽  
Design Variables ◽  
Natural Gas Transmission ◽  
Transmission Pipeline ◽  
Operation Pressure

Abstract The most common joining method in steel gas pipelines is welding; however, this method involves time-consuming, expensive manufacturing and assembly processes to ensure quality in operation. Bell-Spigot joints, which work by mechanical interference, have started to be used as an alternative joining method in steel pipes. Its use has increased due to its reduced assembly time and less post-assembly inspection requirements. In this paper, the structural performance of Bell-Spigot joints in 16-inch steel pipe API 5L X70 with Fusion Bonded Epoxy (FBE) coating for Natural Gas transmission pipeline are evaluated experimentally and by modeling. Test pieces were taken from the gas pipeline after 3 years of operation. Then, tensile pull-out and bending with hydrostatic pressure tests were performed to replicate operating conditions. Deformations, displacements, and the potential presence of leaks were monitored. Experimental results were compared with a Finite Element Method model. Finally, an analytical model for the calculation of stresses and strains in the joint system's components was developed. It was determined that the tightness of the joint depends mainly on the radial interference and the interference length. A higher safety factor can be obtained at the bell-spigot joint than the base pipeline by optimizing selection of joint design variables and the service loading conditions. If the interference pressure is lower than half of the operation pressure, the joint's mechanical strength will be higher or equal that the base pipe.

L-System-Generated Topology Optimization of Compliant Mechanisms Using Graph-Based Interpretation

2018 ◽  
Author(s):  
Brent R. Bielefeldt ◽  
Darren J. Hartl ◽  
Ergun Akleman
Keyword(s):  
Topology Optimization ◽  
Design Space ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Level Set Methods ◽  
Optimization Techniques ◽  
L System ◽  
Design Variables ◽  
System L ◽  
Reconfigurable Structures

Traditional topology optimization techniques, such as density-based and level set methods, have proven successful in identifying potential design configurations but suffer from rapidly increasing design space dimensionality and convergence to local minima. A heuristic alternative to these approaches couples a genetic algorithm with a Lindenmayer System (L-System), which encodes design variables and governs the development of the structure when coupled with some sort of interpreter. This work discusses the development of a graph-based interpretation scheme referred to as Spatial Interpretation for the Development of Reconfigurable Structures (SPIDRS). This framework allows for the effective exploration of the design space using a limited number of design variables. The theory and implementation of this method are detailed, and a compliant mechanism case study is presented to demonstrate the ability of SPIDRS to generate structures capable of achieving multiple design goals.

L-System-Generated Mechanism Topology Optimization Using Graph-Based Interpretation

2019 ◽  
Vol 11 (2) ◽  
Author(s):  
Brent R. Bielefeldt ◽  
Ergun Akleman ◽  
Gregory W. Reich ◽  
Philip S. Beran ◽  
Darren J. Hartl
Keyword(s):  
Topology Optimization ◽  
Design Space ◽  
Level Set Methods ◽  
Optimization Techniques ◽  
L System ◽  
Design Variables ◽  
System L ◽  
Multiple Case ◽  
Multiple Case Studies ◽  
Reconfigurable Structures

Traditional topology optimization techniques, such as density-based and level set methods, have proven successful in identifying potential design configurations for structures and mechanisms but suffer from rapidly increasing design space dimensionality and the possibility of converging to local minima. A heuristic alternative to these approaches couples a genetic algorithm with a Lindenmayer system (L-system), which encodes design variables and governs the development of the structure when coupled with an interpreter to translate genomic information into structural topologies. This work discusses the development of a graph-based interpretation scheme referred to as spatial interpretation for the development of reconfigurable structures (SPIDRS). This framework allows for the effective exploration of mechanism design spaces using a limited number of design variables. The theory and implementation of this method are detailed, and multiple case studies are presented to demonstrate the ability of SPIDRS to generate adaptive structures capable of achieving multiple design goals.

scholarly journals Mode I Crack Propagation Experimental Analysis of Adhesive Bonded Joints Comprising Glass Fibre Composite Material under Impact and Constant Amplitude Fatigue Loading

Materials ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4380
Author(s):  
Alirio Andres Bautista Villamil ◽  
Juan Pablo Casas Rodriguez ◽  
Alicia Porras Holguin ◽  
Maribel Silva Barrera
Keyword(s):  
Crack Propagation ◽  
Structural Integrity ◽  
Crack Propagation Rate ◽  
Fatigue Loading ◽  
Propagation Rate ◽  
Operating Conditions ◽  
Impact Testing ◽  
Mode I ◽  
Mode I Crack ◽  
Constant Amplitude

The T-90 Calima is a low-wing monoplane aircraft. Its structure is mainly composed of different components of composite materials, which are mainly bonded by using adhesive joints of different thicknesses. The T-90 Calima is a trainer aircraft; thus, adverse operating conditions such as hard landings, which cause impact loads, may affect the structural integrity of aircrafts. As a result, in this study, the mode I crack propagation rate of a typical adhesive joint of the aircraft is estimated under impact and constant amplitude fatigue loading. To this end, effects of adhesive thickness on the mechanical performance of the joint under quasistatic loading conditions, impact and constant amplitude fatigue in double cantilever beam (DCB) specimens are experimentally investigated. Cyclic impact is induced using a drop-weight impact testing machine to obtain the crack propagation rate (da/dN) as a function of the maximum strain energy release rate (GImax) diagram; likewise, this diagram is also obtained under constant amplitude fatigue, and both diagrams are compared to determine the effect of each type of loading on the structural integrity of the joint. Results reveal that the crack propagation rate under impact fatigue is three orders of magnitude greater than that under constant amplitude fatigue.

Fully Parametric High-Fidelity CFD Model for the Design Optimisation of the Cyclic Stagger Pattern of a Set of Fan Outlet Guide Vanes

2009 ◽  
Author(s):  
Andrea Milli ◽  
Olivier Bron
Keyword(s):  
Complex Geometry ◽  
Single Point ◽  
Sensitivity Study ◽  
Operating Conditions ◽  
High Fidelity ◽  
Cfd Model ◽  
Design Optimisation ◽  
Guide Vanes ◽  
High Loss ◽  
Design Variables

The present paper deals with the redesign of cyclic variation of a set of fan outlet guide vanes by means of high-fidelity full-annulus CFD. The necessity for the aerodynamic redesign originated from a change to the original project requirement, when the customer requested an increase in specific thrust above the original engine specification. The main objectives of this paper are: 1) make use of 3D CFD simulations to accurately model the flow field and identify high-loss regions; 2) elaborate an effective optimisation strategy using engineering judgement in order to define realistic objectives, constraints and design variables; 3) emphasise the importance of parametric geometry modelling and meshing for automatic design optimisation of complex turbomachinery configurations; 4) illustrate that the combination of advanced optimisation algorithms and aerodynamic expertise can lead to successful optimisations of complex turbomachinery components within practical time and costs constrains. The current design optimisation exercise was carried out using an in-house set of software tools to mesh, resolve, analyse and optimise turbomachinery components by means of Reynolds-averaged Navier-Stokes simulations. The original configuration was analysed using the 3D CFD model and thereafter assessed against experimental data and flow visualisations. The main objective of this phase was to acquire a deep insight of the aerodynamics and the loss mechanisms. This was important to appropriately limit the design scope and to drive the optimisation in the desirable direction with a limited number of design variables. A mesh sensitivity study was performed in order to minimise computational costs. Partially converged CFD solutions with restart and response surface models were used to speed up the optimisation loop. Finally, the single-point optimised circumferential stagger pattern was manually adjusted to increase the robustness of the design at other flight operating conditions. Overall, the optimisation resulted in a major loss reduction and increased operating range. Most important, it provided the project with an alternative and improved design within the time schedule requested and demonstrated that CFD tools can be used effectively not only for the analysis but also to provide new design solutions as a matter of routine even for very complex geometry configurations.

Improvement of the Static and Dynamic Characteristics of Magnetic Head Sliders by Optimum Design

1999 ◽  
Vol 122 (1) ◽  
pp. 280-287 ◽  
Author(s):  
Hiromu Hashimoto ◽  
Yasuhisa Hattori
Keyword(s):  
Objective Function ◽  
Optimum Design ◽  
Amplitude Ratio ◽  
Optimization Technique ◽  
Hard Disk Drives ◽  
Maximum Amplitude ◽  
Disk Surface ◽  
Operating Conditions ◽  
Magnetic Head ◽  
Design Variables

The aim of this paper is to develop a general methodology for the optimum design of magnetic head sliders in improving the spacing characteristics between a slider and disk surface under static and dynamic operating conditions of hard disk drives and to present an application of the methodology to the IBM 3380-type slider design. To generate the optimal design variables, the objective function is defined as the weighted sum of the minimum spacing, the maximum difference in the spacing due to variation of the radial location of the head, and the maximum amplitude ratio of the slider motion. Slider rail width, taper length, taper angle, suspension position, and preload are selected as the design variables. Before the optimization of the head, the effects of these five design variables on the objective function are examined by a parametric study, and then the optimum design variables are determined by applying the hybrid optimization technique, combining the direct search method and successive quadratic programming. From the obtained results, the effectiveness of optimum design on the spacing characteristics of magnetic heads is clarified. [S0742-4787(00)03701-2]

Performance Characterization of a Twin Scroll Volute for Turbocharging Applications

2018 ◽  
Author(s):  
Carlo Cravero ◽  
Mario La Rocca ◽  
Andrea Ottonello
Keyword(s):  
Experimental Data ◽  
Scientific Literature ◽  
Aerodynamic Performance ◽  
Operating Conditions ◽  
Automatic Design ◽  
Cfd Model ◽  
Radial Turbine ◽  
Wide Range ◽  
Partial Admission

The use of twin scroll volutes in radial turbine for turbocharging applications has several advantages over single passage volute related to the engine matching and to the overall compactness. Twin scroll volutes are of increasing interest in power unit development but the open scientific literature on their performance and modelling is still quite limited. In the present work the performance of a twin scroll volute for a turbocharger radial turbine are investigated in some detail in a wide range of operating conditions at both full and partial admission. A CFD model for the volute have been developed and preliminary validated against experimental data available for the radial turbine. Then the numerical model has been used to generate the database of solutions that have been investigated and used to extract the performance. Different parameters and indices are introduced to describe the volute aerodynamic performance in the wide range of operating conditions chosen. The above parameters can be used for volute development or matching with a given rotor or efficiently implemented in automatic design optimization strategies.

Evaluation of Fuel Preparation Systems for Lean Premixing-Prevaporizing Combustors

1986 ◽  
Vol 108 (2) ◽  
pp. 391-395
Author(s):  
W. J. Dodds ◽  
E. E. Ekstedt
Keyword(s):  
System Design ◽  
Large Scale ◽  
Fuel Injection ◽  
Operating Conditions ◽  
Turbine Engine ◽  
Fuel Injectors ◽  
Design Concepts ◽  
Mixture Preparation ◽  
Design Variables ◽  
System Length

A series of tests was conducted to provide data for the design of premixing-prevaporizing fuel-air mixture preparation systems for aircraft gas turbine engine combustors. Fifteen configurations of four different fuel-air mixture preparation system design concepts were evaluated to determine fuel-air mixture uniformity at the system exit over a range of conditions representative of cruise operation for a modern commercial turbofan engine. Operating conditions, including pressure, temperature, fuel-air ratio, and velocity had no clear effect on mixture uniformity in systems which used low-pressure fuel injectors. However, performance of systems using pressure atomizing fuel nozzles and large-scale mixing devices was shown to be sensitive to operating conditions. Variations in system design variables were also evaluated and correlated. Mixture uniformity improved with increased system length, pressure drop, and number of fuel injection points per unit area. A premixing system compatible with the combustor envelope of a typical combustion system and capable of providing mixture nonuniformity (standard deviation/mean) below 15% over a typical range of cruise operating conditions was demonstrated.

scholarly journals Tuning the Properties of PNIPAm-Based Hydrogel Scaffolds for Cartilage Tissue Engineering

Polymers ◽  
2021 ◽  
Vol 13 (18) ◽  
pp. 3154
Author(s):  
Md Mohosin Rana ◽  
Hector De la Hoz Siegler
Keyword(s):  
Tissue Engineering ◽  
Physical Properties ◽  
Tissue Regeneration ◽  
Structural Integrity ◽  
Cartilage Tissue ◽  
Design Parameters ◽  
Comprehensive Overview ◽  
Hydrogel Scaffolds ◽  
Design Variables

Poly(N-isopropylacrylamide) (PNIPAm) is a three-dimensional (3D) crosslinked polymer that can interact with human cells and play an important role in the development of tissue morphogenesis in both in vitro and in vivo conditions. PNIPAm-based scaffolds possess many desirable structural and physical properties required for tissue regeneration, but insufficient mechanical strength, biocompatibility, and biomimicry for tissue development remain obstacles for their application in tissue engineering. The structural integrity and physical properties of the hydrogels depend on the crosslinks formed between polymer chains during synthesis. A variety of design variables including crosslinker content, the combination of natural and synthetic polymers, and solvent type have been explored over the past decade to develop PNIPAm-based scaffolds with optimized properties suitable for tissue engineering applications. These design parameters have been implemented to provide hydrogel scaffolds with dynamic and spatially patterned cues that mimic the biological environment and guide the required cellular functions for cartilage tissue regeneration. The current advances on tuning the properties of PNIPAm-based scaffolds were searched for on Google Scholar, PubMed, and Web of Science. This review provides a comprehensive overview of the scaffolding properties of PNIPAm-based hydrogels and the effects of synthesis-solvent and crosslinking density on tuning these properties. Finally, the challenges and perspectives of considering these two design variables for developing PNIPAm-based scaffolds are outlined.

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