scholarly journals Optimization of the Main Landing Gear Structure of LSU-02NGLD

2021 ◽  
Vol 4 (1) ◽  
pp. 30
Author(s):  
Fajar Ari Wandono
Keyword(s):  
Total Mass ◽  
Landing Gear ◽  
Structure Model ◽  
Cross Sectional ◽  
Beam Elements ◽  
Finite Element Software ◽  
Design Variables ◽  
Aerial Vehicle ◽  
The Cross ◽  
New Generation

The mass of the landing gear structure becomes an important aspect of the total mass of the UAV (unmanned aerial vehicle). Therefore, many efforts have been made to reduce the mass of the landing gear by performing structural optimization. Reducing the mass of the landing gear structure can be used as a substitute to increase the payload on the UAV. The landing gear structure in this paper is the main landing gear of LSU-02NGLD (LAPAN Surveillance UAV series 02 New Generation Low Drag). LSU-02NGLD is a UAV that has 2.9 m of wingspan with a total mass of 21 kg. This paper aims to optimize the main landing gear structure so that optimization can reduce the mass. The optimization was carried out using the finite element software by modeling the main landing gear structure as a 1D beam element. There were 9 beam elements in the main landing gear structure model. The cross-sectional width (w) and the cross-sectional height (h) for each element were used as design variables. The objective of the optimization was to minimize the mass while maintaining maximum bending stress not greater than 20 MPa, displacement in y-direction not greater than 1 mm, and displacement in z-direction not greater than 0.1 mm. The optimization result showed that the mass reduction of the main landing gear structure was 50%, with all constraints fulfilled.

Shape Optimal Design of Elastic Planar Frames With Elastic and Skew-Sliding Supports

1997 ◽  
Author(s):  
M. M. Oblak ◽  
M. Kegl ◽  
D. Dinevski
Keyword(s):  
Optimal Design ◽  
Linear Response ◽  
Frame Structure ◽  
Design Element ◽  
Cross Sectional ◽  
Design Elements ◽  
Beam Elements ◽  
Design Variables ◽  
Planar Frames ◽  
Gradient Based

Abstract This paper describes an approach to shape optimal design of elastic, statically loaded, planar frames with kinematically non-linear response where special attention is focused on consideration of elastic and skew-sliding supports. A frame structure is treated as to be assembled from several design elements each of them being defined as a Bézier curve. The design variables may influence the position and the shape of each design element, the cross-sectional properties of beam elements, the elastic properties of the supports as well as the angles of inclination of sliding supports. Highly accurate, locking-free and initially curved beam elements are employed to ensure accurate and reliable results. The optimal design problem is defined in a general form and its solution, by employing gradient based methods of mathematical programming, is discussed briefly. The theory is illustrated with a numerical example.

scholarly journals Zero-Coupon Yields and the Cross-Section of Bond Prices

2021 ◽  
Author(s):  
N Aaron Pancost
Keyword(s):  
Term Structure ◽  
Yield Curve ◽  
Structure Model ◽  
Bond Prices ◽  
Cross Sectional ◽  
Term Structure Model ◽  
No Arbitrage ◽  
Affine Model ◽  
The Cross ◽  
Coupon Bond

Abstract I estimate a dynamic term structure model on an unbalanced panel of Treasury coupon bonds, without relying on an interpolated zero-coupon yield curve. A linearity-generating model, which separates the parameters that govern the cross-sectional and time-series moments of the model, takes about 8 min to estimate on a sample of over 1 million bond prices. The traditional exponential affine model takes about 2 hr, because of a convexity term in coupon-bond prices that cannot be concentrated out of the cross-sectional likelihood. I quantify the on-the-run premium and a “notes versus bonds” premium from 1990 to 2017 in a single, easy-to-estimate no-arbitrage model.

scholarly journals The cross-sectional effects of ribbon arch wires on Class II malocclusion intermaxillary traction: a three-dimensional finite element analysis

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Qin Xie ◽  
Duo Li
Keyword(s):  
Finite Element ◽  
Vertical Displacement ◽  
Class Ii ◽  
Class Ii Malocclusion ◽  
Element Analysis ◽  
Cross Sectional ◽  
Finite Element Software ◽  
Anterior Teeth ◽  
Round Wire ◽  
The Cross

Abstract Background The application of intermaxillary traction is often accompanied by the unexpected movement of dentition, especially anchorage teeth. The aim of this study was to comprehensively compare the influence of cross-sectional shape of ribbon arch wires with edgewise and round wires on intermaxillary traction in Class II malocclusion treatment using FEA simulation. Methods The dentofacial structure was simulated in finite element software. A retraction force of 1.5 N was applied to different cross-sectional orthodontic arch wires: a ribbon wire (0.025 × 0.017-in. and 0.025 × 0.019-in.), a rectangular wire (0.017 × 0.025-in. and 0.019 × 0.025-in.) and a round wire (Φ 0.018-in. and Φ 0.020-in.). Results Among the three groups, ribbon wire (0.025 × 0.017-in. and 0.025 × 0.019-in.) exhibited the lowest displacement in the X-axis (12.61 μm and 12.77 μm, respectively) and Z-axis (8.99 μm and 9.06 μm, respectively). However, the 0.025 × 0.017-in. ribbon wire showed the highest Y-axis displacement. In the round wire group, Φ 0.020-in. wire displayed less rotation than Φ 0.018-in. wire, where the sagittal, frontal and occlusal rotation of Φ 0.020-in. wire was almost half of that of Φ 0.018-in. wire. The movement of the first molar region was intermediate between the ribbon arch group and the round wire group. Notably, the values of the 0.025 × 0.017-in. arch wire displacement, which were higher than those of any other group, peaked at 0.019 mm in the central incisor region with a spike-like shape. The deformation range of the Φ 0.018-in. wire group was the largest in this study. Conclusions The cross-section of the arch wire influenced force delivery in Class II intermaxillary traction. With the same shape, a larger cross-sectional area led to less mandibular dentition movement. For the rectangular arch wire and ribbon arch wire groups, since the height and width were inverted, the vertical displacement of anchorage teeth in the ribbon wire group was reduced, but the possibility of buccal tipping in mandibular anterior teeth also increased.

scholarly journals The cross-sectional effects of ribbon arch wires on Class II malocclusion intermaxillary traction: A three-dimensional finite element analysis

2021 ◽  
Author(s):  
Qin Xie ◽  
Duo Li
Keyword(s):  
Finite Element ◽  
Vertical Displacement ◽  
Class Ii ◽  
Class Ii Malocclusion ◽  
Element Analysis ◽  
Cross Sectional ◽  
Finite Element Software ◽  
Anterior Teeth ◽  
Round Wire ◽  
The Cross

Abstract Background: The application of intermaxillary traction is often accompanied by the unexpected movement of dentition, especially anchorage teeth. The aim of this study was to comprehensively compare the influence of cross-sectional shape of ribbon arch wires with edgewise and round wires on intermaxillary traction in Class II malocclusion treatment using FEA simulation.Methods: The dentofacial structure was simulated in finite element software. A retraction force of 1.5 N was applied to different cross-sectional orthodontic arch wires: a ribbon wire (0.025×0.017-inch and 0.025×0.019-inch), a rectangular wire (0.017×0.025-inch and 0.019×0.025-inch) and a round wire (Φ 0.018-inch and Φ 0.020-inch).Results: Among the three groups, ribbon wire (0.025×0.017-inch and 0.025×0.019-inch) exhibited the lowest displacement in the X-axis (12.61 μm and 12.77 μm, respectively) and Z-axis (8.99 μm and 9.06 μm, respectively). However, the 0.025×0.017-inch ribbon wire showed the highest Y-axis displacement. In the round wire group, Φ 0.020-inch wire displayed less rotation than Φ 0.018-inch wire, where the sagittal, frontal and occlusal rotation of Φ 0.020-inch wire was almost half of that of Φ 0.018-inch wire. The movement of the first molar region was intermediate between the ribbon arch group and the round wire group. Notably, the values of the 0.025×0.017-inch arch wire displacement, which were much higher than those of any other group, peaked at 0.019 mm in the central incisor region with a spike-like shape. The deformation range of the Φ 0.018-inch wire group was the largest in this study.Conclusions: The cross-section of the arch wire influenced force delivery in Class II intermaxillary traction. With the same shape, a larger cross-sectional area would lead to less mandibular dentition movement. For the rectangular arch wire and ribbon arch wire groups, since the height and width were inverted, the vertical displacement of anchorage teeth in the ribbon wire group was significantly reduced, but the possibility of buccal tipping in mandibular anterior teeth also increased.

Optimization of an Automotive Structure Subject to Harmonic Excitation

1999 ◽  
Author(s):  
Arnoldo Garcia ◽  
Arnold Lumsdaine ◽  
Ying Yao
Keyword(s):  
Finite Element ◽  
Optimal Design ◽  
Optimization Theory ◽  
Harmonic Excitation ◽  
Cross Sectional ◽  
Beam Elements ◽  
Finite Element Software ◽  
Original Weight ◽  
Engineering Problems ◽  
Discrete Finite Element

Abstract Optimization theory has been used to obtain solutions to a variety of engineering problems involving beam vibration. In this study, the objective is to design a structure that uses the minimum amount of material. The structure examined is a beam undergoing coupled bending and torsion, as is common in automotive structure beams. The objective of this study is to minimize the weight of an automotive structure subject to harmonic excitation. The automotive structure is modeled with beam elements in I-DEAS, a computer-aided engineering and finite element software. For each given length, its cross-sectional area is optimized by a discrete finite element method. In addition, a bracket was modeled in conjunction with the automotive structure. Although the optimal design of beams undergoing forced harmonic loading is available in the literature, to the authors’ knowledge, optimal design of such structures including an intermediate support have not been considered. The placement of the bracket was also treated as a design parameter by varying its location and size in the optimization process. Results show that the total mass after optimization had a mass reduction of 91% when compared to the original weight.

Toward a Unified Design Approach for Both Compliant Mechanisms and Rigid-Body Mechanisms: Module Optimization

2015 ◽  
Vol 137 (12) ◽  
Author(s):  
Lin Cao ◽  
Allan T. Dolovich ◽  
Arend L. Schwab ◽  
Just L. Herder ◽  
Wenjun (Chris) Zhang
Keyword(s):  
Rigid Body ◽  
Compliant Mechanisms ◽  
Optimization Approach ◽  
Structure Model ◽  
Dimensional Synthesis ◽  
Beam Elements ◽  
Compliant Joints ◽  
Design Variables ◽  
Rigid Joints ◽  
Synthesis Approach

Rigid-body mechanisms (RBMs) and compliant mechanisms (CMs) are traditionally treated in significantly different ways. In this paper, we present a synthesis approach that is appropriate for both RBMs and CMs. In this approach, RBMs and CMs are generalized into modularized mechanisms that consist of five basic modules, including compliant links (CLs), rigid links (RLs), pin joints (PJs), compliant joints (CJs), and rigid joints (RJs). The link modules and joint modules are modeled through beam elements and hinge elements, respectively, in a geometrically nonlinear finite-element solver, and subsequently a beam-hinge ground structure model is proposed. Based on this new model, a link and joint determination approach—module optimization—is developed for the type and dimensional synthesis of both RBMs and CMs. In the module optimization approach, the states (both presence or absence and sizes) of joints and links are all design variables, and one may obtain an RBM, a partially CM, or a fully CM for a given mechanical task. Three design examples of path generators are used to demonstrate the effectiveness of the proposed approach to the type and dimensional synthesis of RBMs and CMs.

An Efficient Approximation Method for Structural Synthesis with Reference to Space Structures

1987 ◽  
Vol 2 (3) ◽  
pp. 165-175 ◽  
Author(s):  
E. Salajegheh ◽  
G. N. Vanderplaats
Keyword(s):  
Structural Response ◽  
Optimal Solution ◽  
Cross Sectional ◽  
Non Linear Programming ◽  
Design Variables ◽  
Structural Responses ◽  
Internal Forces ◽  
The Cross ◽  
Nodal Displacements ◽  
Efficient Approximation

A method is presented for the optimum design of structures which is very robust and efficient in terms of the number of required analyses of the structure. Some explicit approximation expressions are generated for the structural response quantities such as nodal displacements, forces and frequencies as functions of the cross-sectional properties. By substituting these expressions into the constraint equations, the design task becomes a non-linear programming problem which is an explicit problem in terms of the design variables. The solution of this problem gives the actual cross-sectional dimensions. The method is an iterative technique and the results indicate that the convergence to the optimal solution results indicate that the convergence to the optimal solution is very rapid. The robustness of the proposed method is due to the generation of explicit approximate relations for the structural response quantities, as in the past the design constraints were approximated. Also a high quality approximation is obtained for the internal forces directly without using the approximate values of the displacements. The quality of approximations is enhanced by expressing the structural responses, in particular, the frequencies with respect to the cross-sectional areas and second moment of inertias instead of using the cross-sectional dimensions. A double-layer grid and a grillage are chosen as test cases, the results of which are presented.

scholarly journals Optimization and Experimental Study of the Subsea Retractable Connector Rubber Packer based on Mooney-Rivlin Constitutive Model

2021 ◽  
Vol 9 (12) ◽  
pp. 1391
Author(s):  
Kefeng Jiao ◽  
Feihong Yun ◽  
Zheping Yan ◽  
Gang Wang ◽  
Peng Jia ◽  
...  
Keyword(s):  
Structural Parameters ◽  
Optimization Method ◽  
Cross Sectional ◽  
Factors Affecting ◽  
Response Surface Optimization ◽  
Multi Objective Genetic Algorithm ◽  
Design Variables ◽  
Sealing Performance ◽  
The Cross ◽  
Sectional Shape

The sealing performance of the rubber packer is of vital importance for the subsea retractable connector, and the cross-sectional shape of the rubber packer is one of the most important factors affecting it. The compression distance of the rubber packer is increased by 19.54% utilizing the established two-dimensional numerical model. In addition, a new parameter called the anti-shoulder extrusion variable was defined in this paper. Shoulder extrusion will not occur when using this variable as a constraint during simulation. In general, the upper end and the lower end of a rubber packer are subject to different constraints, and the structural parameters of the rubber packer affect each other in terms of sealing performance. Therefore, the importance and originality of this study are exploring the optimization of the thickness and chamfer angles of the upper and lower ends of the rubber packer by use of a combination of the response surface optimization method and the multi-objective genetic algorithm, taking the thickness and chamfer angles of the upper and lower ends as design variables, and the stress on the inner side of the casing wall and the axial force of the compressed rubber packer as optimization objectives. Besides that, the anti-shoulder extrusion variables are also introduced as constraints to prevent shoulder extrusion. Ultimately, the cross-sectional shape of the rubber packer with a smaller-thickness and larger-angle upper end, and a larger-thickness and smaller-angle lower end can be obtained. The result to emerge from the test in this paper is that the pipe pressure that can be sealed by the optimized rubber packer structure is 25.61% higher than that before optimization. The anti-shoulder extrusion variable and the asymmetric cross-sectional shape of the rubber packer proposed in this paper shed new light on the finite element simulation of rubber and the research on similar seals.

On the cross-sectional shape of the cellulose crystallites in the tunicate Halocynthia papillosa

1990 ◽  
Vol 48 (3) ◽  
pp. 566-567
Author(s):  
J.-F. Revol ◽  
Y. Van Daele ◽  
F. Gaill
Keyword(s):  
Contrast Imaging ◽  
Animal Kingdom ◽  
Bright Field ◽  
Field Mode ◽  
Cross Sectional ◽  
Ultrathin Sections ◽  
The Cross ◽  
Sectional Shape ◽  
Valonia Ventricosa ◽  
C Nmr

The only form of cellulose which could unequivocally be ascribed to the animal kingdom is the tunicin that occurs in the tests of the tunicates. Recently, high-resolution solid-state l3C NMR revealed that tunicin belongs to the Iβ form of cellulose as opposed to the Iα form found in Valonia and bacterial celluloses. The high perfection of the tunicin crystallites led us to study its crosssectional shape and to compare it with the shape of those in Valonia ventricosa (V.v.), the goal being to relate the cross-section of cellulose crystallites with the two allomorphs Iα and Iβ.In the present work the source of tunicin was the test of the ascidian Halocvnthia papillosa (H.p.). Diffraction contrast imaging in the bright field mode was applied on ultrathin sections of the V.v. cell wall and H.p. test with cellulose crystallites perpendicular to the plane of the sections. The electron microscope, a Philips 400T, was operated at 120 kV in a low intensity beam condition.

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