Multiobjective optimization of the LASER aircraft wing’s composite structural design

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Juan Tamassia Ricco ◽  
Rogerio Frauendorf Faria Coimbra ◽  
Guilherme Ferreira Gomes
Keyword(s):  
Multiobjective Optimization ◽  
Laminated Composite ◽  
Element Analysis ◽  
Content Type ◽  
Aircraft Wings ◽  
Internal Structures ◽  
Material Choice ◽  
Predominant Orientation ◽  
Composite Laser

Purpose Aircraft wings, one of the most important parts of an aircraft, have seen changes in its topological and design arrangement of both the internal structures and external shape during the past decades. This study, a numerical, aims to minimize the weight of multilaminate composite aerospace structures using multiobjective optimization. Design/methodology/approach The methodology started with the determination of the requirements, both imposed by the certifying authority and those inherent to the light, aerobatic, simple, economic and robust (LASER) project. After defining the requirements, the loads that the aircraft would be subjected to during its operation were defined from the flight envelope considering finite element analysis. The design vector consists of material choice for each laminate of the structure (20 in total), ply number and lay-up sequence (respecting the manufacturing rules) and main spar position to obtain a lightweight and cheap structure, respecting the restrictions of stress, margins of safety, displacements and buckling. Findings The results obtained indicated a predominance of the use of carbon fiber. The predominant orientation found on the main spar flange was 0° with its location at 28% of the local chord, in the secondary and main web were ±45°, the skins also had the main orientation at ±45°. Originality/value The key innovations in this paper include the evaluation, development and optimization of a laminated composite structure applied to a LASER aircraft wings considering both structural performance and manufacturing costs in multiobjetive optimization. This paper is one of the most advanced investigations performed to composite LASER aircraft.

Influence of fiber stacking sequences and matrix materials on mechanical and vibration behavior of jute/carbon hybrid composites

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Sathiyamoorthy Margabandu ◽  
Senthil Kumar Subramaniam
Keyword(s):  
Tensile Strength ◽  
Hybrid Composites ◽  
Low Cost ◽  
Laminated Composite ◽  
Experimental Results ◽  
Element Analysis ◽  
Content Type ◽  
Vibration Behavior ◽  
Damping Behavior ◽  
Composite Models

Purpose The study aims to investigate the influence of fabric hybridization, stacking sequences and matrix materials on the tensile strength and damping behavior of jute/carbon reinforced hybrid composites. Design/methodology/approach The hybrid composites were fabricated with different sequences of fabric plies in epoxy and polyester matrix using a hand layup technique. The tensile and vibration characteristics were evaluated on the hybrid laminated composite models using finite element analysis (FEA), and the results were validated experimentally according to ASTM standards. The surface morphology of the fractured specimens was studied using the scanning electron microscope. Findings The experimental results revealed that the position of jute layers in the hybrid composites has a significant influence on the tensile strength and damping behavior. The hybrid composite with jute fiber at the surface sides and carbon fibers at the middle exhibited higher tensile strength with superior damping properties. Further, it is found that the experimental results are in good coherence with the FEA results. Originality/value The less weight and low-cost hybrid composites were fabricated by incorporating the jute and carbon fabrics in interply configurations. The influences of fabric hybridization, stacking arrangements and matrix materials on the tensile and vibration behavior of jute/carbon hybrid composites have been numerically evaluated and the results were experimentally validated.

Computational investigation of ballistic-impact behavior and penetration resistance of a nacre-like ceramic/polymer laminated composite

2017 ◽  
Vol 8 (1) ◽  
pp. 79-107 ◽  
Author(s):  
Mica Grujicic ◽  
S. Ramaswami ◽  
Jennifer Snipes
Keyword(s):  
Critical Role ◽  
Laminated Composite ◽  
Areal Density ◽  
Penetration Resistance ◽  
Ballistic Impact ◽  
Impact Behavior ◽  
Element Analysis ◽  
Content Type ◽  
Composite Armor ◽  
Improved Performance

Purpose Nacre is a biological material constituting the innermost layer of the shells of gastropods and bivalves. It consists of polygonal tablets of aragonite, tessellated to form individual layers and having the adjacent layers as well as the tablets within a layer bonded by a biopolymer. Due to its highly complex hierarchical microstructure, nacre possesses an outstanding combination of mechanical properties, the properties which are far superior to the ones that are predicted using techniques such as the rule of mixtures. Given these properties, a composite armor the structure of which mimics that of nacre may have improved performance over a monolithic armor having a similar composition and an identical areal density. The paper aims to discuss these issues. Design/methodology/approach In the present work, an attempt is made to model a nacre-like composite armor consisting of B4C tablets and polyurea tablet/tablet interfaces. The armor is next tested with respect to impact by a solid right circular cylindrical (SRCC) rigid projectile, using a transient non-linear dynamics finite-element analysis. The ballistic-impact response and the penetration resistance of the armor are then compared with that of the B4C monolithic armor having an identical areal density. Furthermore, the effect of various nacre microstructural features (e.g. surface profiling, micron-scale asperities, mineral bridges between the overlapping tablets lying in adjacent layers, and B4C nano-crystallinity) on the ballistic-penetration resistance of the composite armor is investigated in order to identify an optimal nacre-like composite armor architecture having the largest penetration resistance. Findings The results obtained clearly show that a nacre-like armor possesses a superior penetration resistance relative to its monolithic counterpart, and that the nacre microstructural features considered play a critical role in the armor-penetration resistance. Originality/value The present work indicates that for a given choice of armor material, penetration resistance may be improved by choosing a structure resembling that of nacre.

Hybrid Bishop-Hill model combined finite element analysis for elastic-yield limited design

2015 ◽  
Vol 32 (6) ◽  
pp. 1814-1836
Author(s):  
Ribeka Takahashi ◽  
David T. Fullwood ◽  
Travis M. Rampton ◽  
Darrell J. Skousen ◽  
Brent L. Adams ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Material Anisotropy ◽  
Element Analysis ◽  
Hill Model ◽  
Content Type ◽  
Local Stresses ◽  
Material Choice ◽  
Practical Tool ◽  
Choice Processing

Purpose – Microstructure-sensitive design (MSD), for optimal performance of engineering components that are sensitive to material anisotropy, has largely been confined to the realm of theory. The purpose of this paper is to insert the MSD framework into a finite element environment in order to arrive at a practical tool for improved selection and design of materials for critical engineering situations. Design/methodology/approach – This study applies the recently developed Hybrid Bishop-Hill (HBH) model to map the yield surface of anisotropic oxygen free electronic copper. Combining this information with the detailed local stresses determined via finite element analysis (FEA), a “configurational yield stress” is determined for the entire component. By varying the material choice/processing conditions and selecting the directionality of anisotropy, an optimal configuration is found. Findings – The paper provides a new FEA-based framework for MSD for yield-limited situations. The approach identified optimal directionality and processing configurations for three engineering situations that are particularly sensitive to material anisotropy. Research limitations/implications – The microstructure design space for this study is limited to a selection of eight copper materials produced by a range of processing methods, but is generalizable to many materials that exhibit anisotropic behavior. Originality/value – The introduction of MSD methodology into a finite element environment is a first step toward a comprehensive designer toolkit for exploiting the anisotropy of general materials (such as metals) in a way that is routinely undertaken in the world of fiber-based composite materials. While the gains are not as sizeable (due to the less-extreme anisotropy), in many applications they may be extremely important.

Evaluation of web reinforcements in prestressed concrete box girders through shear-transverse bending domains

2020 ◽  
pp. 136943322098170
Author(s):  
Michele Fabio Granata ◽  
Antonino Recupero
Keyword(s):  
Analytical Model ◽  
Prestressed Concrete ◽  
3D Analysis ◽  
Box Girders ◽  
Element Analysis ◽  
Cross Sectional ◽  
Interaction Domains ◽  
Global And Local ◽  
Resultant Forces

In concrete box girders, the amount and distribution of reinforcements in the webs have to be estimated considering the local effects due to eccentric external loads and cross-sectional distortion and not only the global effect due to the resultant forces of a longitudinal analysis: shear, torsion and bending. This work presents an analytical model that allows designers to take into account the interaction of all these effects, global and local, for the determination of the reinforcements. The model is based on the theory of stress fields and it has been compared to a 3D finite element analysis, in order to validate the interaction domains. The results show how the proposed analytical model allows an easy and reliable reinforcement evaluation, in agreement with a more refined 3D analysis but with a reduced computational burden.

Determination of collapse moment of different angled pipe bends with initial geometric imperfection subjected to in-plane bending moments

2021 ◽  
pp. 095440622199640
Author(s):  
Manish Kumar ◽  
Pronab Roy ◽  
Kallol Khan
Keyword(s):  
Finite Element ◽  
Cross Section ◽  
Circular Cross Section ◽  
Initial Imperfection ◽  
Bend Angle ◽  
Bending Moments ◽  
Element Analysis ◽  
Geometric Imperfection ◽  
Initial Geometric Imperfection

From the recent literature, it is revealed that pipe bend geometry deviates from the circular cross-section due to pipe bending process for any bend angle, and this deviation in the cross-section is defined as the initial geometric imperfection. This paper focuses on the determination of collapse moment of different angled pipe bends incorporated with initial geometric imperfection subjected to in-plane closing and opening bending moments. The three-dimensional finite element analysis is accounted for geometric as well as material nonlinearities. Python scripting is implemented for modeling the pipe bends with initial geometry imperfection. The twice-elastic-slope method is adopted to determine the collapse moments. From the results, it is observed that initial imperfection has significant impact on the collapse moment of pipe bends. It can be concluded that the effect of initial imperfection decreases with the decrease in bend angle from 150∘ to 45∘. Based on the finite element results, a simple collapse moment equation is proposed to predict the collapse moment for more accurate cross-section of the different angled pipe bends.

scholarly journals Determination of the region of the limiting states occurrence in RVS-20000 with the subsidence of the external bottom contour

2018 ◽  
Vol 239 ◽  
pp. 06002
Author(s):  
P.V. Chepur ◽  
A.A. Tarasenko ◽  
A.A. Gruchenkova
Keyword(s):  
Technical Condition ◽  
Element Analysis ◽  
Metal Structures ◽  
Software Complex ◽  
Managerial Decisions ◽  
The Finite Element Analysis ◽  
Steel Tank ◽  
Intrinsic Stiffness ◽  
Bottom Contour

The problem of the limiting states occurrence in the structures of a vertical steel tank is investigated in this work. To study the SSS of the metal structures of the object, the authors created a numerical model of the RVS-20000 tank in the ANSYS software complex. The model considers the maximum number of elements with their geometry and connections affecting the tank SSS under non-axisymmetric loading, including beyond the elasticity of steel. Dependences between the parameters of intrinsic stiffness of the VST are obtained. The results of the finite element analysis made it possible to develop a technique for assessing the technical condition of the structure with the development of irregular subsidence of the external bottom contour. The proposed technique can be used by both operating and design organizations in making managerial decisions regarding the repair of RVS-20000 subjected to the base subsidence.

Locating complex eigenvalues for analytical eddy-current models used to detect flaws

2019 ◽  
Vol 38 (6) ◽  
pp. 1800-1809
Author(s):  
Grzegorz Tytko ◽  
Łukasz Dawidowski
Keyword(s):  
Eddy Current ◽  
Design Methodology ◽  
Complex Function ◽  
Precise Determination ◽  
Argument Principle ◽  
Content Type ◽  
Conductive Material ◽  
Complex Roots ◽  
Complex Eigenvalues

Purpose Discrete eigenvalues occur in eddy current problems in which the solution domain was truncated on its edge. In case of conductive material with a hole, the eigenvalues are complex numbers. Their computation consists of finding complex roots of a complex function that satisfies the electromagnetic interface conditions. The purpose of this paper is to present a method of computing complex eigenvalues that are roots of such a function. Design/methodology/approach The proposed approach involves precise determination of regions in which the roots are found and applying sets of initial points, as well as the Cauchy argument principle to calculate them. Findings The elaborated algorithm was implemented in Matlab and the obtained results were verified using Newton’s method and the fsolve procedure. Both in the case of magnetic and nonmagnetic materials, such a solution was the only one that did not skip any of the eigenvalues, obtaining the results in the shortest time. Originality/value The paper presents a new effective method of locating complex eigenvalues for analytical solutions of eddy current problems containing a conductive material with a hole.

Reliability analysis of static liquefaction of loose sand using the random finite element method

2015 ◽  
Vol 32 (7) ◽  
pp. 2100-2119 ◽  
Author(s):  
Ali Johari ◽  
Jaber Rezvani Pour ◽  
Akbar Javadi
Keyword(s):  
Finite Element ◽  
Pressure Ratio ◽  
Monotonic Loading ◽  
Unit Weight ◽  
Soil Parameters ◽  
Loose Sand ◽  
Element Analysis ◽  
Content Type ◽  
Static Liquefaction ◽  
Random Finite Element

Purpose – Liquefaction of soils is defined as significant reduction in shear strength and stiffness due to increase in pore water pressure. This phenomenon can occur in static (monotonic) or dynamic loading patterns. However, in each pattern, the inherent variability of the soil parameters indicates that this problem is of a probabilistic nature rather than being deterministic. The purpose of this paper is to present a method, based on random finite element method, for reliability assessment of static liquefaction of saturated loose sand under monotonic loading. Design/methodology/approach – The random finite element analysis is used for reliability assessment of static liquefaction of saturated loose sand under monotonic loading. The soil behavior is modeled by an elasto-plastic effective stress constitutive model. Independent soil parameters including saturated unit weight, peak friction angle and initial plastic shear modulus are selected as stochastic parameters which are modeled using a truncated normal probability density function (pdf). Findings – The probability of liquefaction is assessed by pdf of modified pore pressure ratio at each depth. For this purpose pore pressure ratio is modified for monotonic loading of soil. It is shown that the saturated unit weight is the most effective parameter, within the selected stochastic parameters, influencing the static soil liquefaction. Originality/value – This research focuses on the reliability analysis of static liquefaction potential of sandy soils. Three independent soil parameters including saturated unit weight, peak friction angle and initial plastic shear modulus are considered as stochastic input parameters. A computer model, coded in MATLAB, is developed for the random finite element analysis. For modeling of the soil behavior, a specific elasto-plastic effective stress constitutive model (UBCSAND) was used.

scholarly journals Determination of the Catalytic Base in Family 48 Glycosyl Hydrolases

2011 ◽  
Vol 77 (17) ◽  
pp. 6274-6276 ◽  
Author(s):  
Maxim Kostylev ◽  
David B. Wilson
Keyword(s):  
Aspartic Acid ◽  
Site Directed Mutagenesis ◽  
Directed Mutagenesis ◽  
Thermobifida Fusca ◽  
Glycosyl Hydrolases ◽  
Content Type ◽  
Modeling Data ◽  
Partial Activity

ABSTRACTThe catalytic base in family 48 glycosyl hydrolases has not been previously established experimentally. Based on structural and modeling data published to date, we used site-directed mutagenesis and azide rescue activity assays to show definitively that the catalytic base inThermobifida fuscaCel48A is aspartic acid 225. Of the tested mutants, only Cel48A with the D225E mutation retained partial activity on soluble and insoluble substrates. In azide rescue experiments, only the D225G mutation, in the smallest residue tested, showed an increase in activity with added azide.

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