scholarly journals A Study on the Shape Selection of Mechanical Fastening for the Repair of Fighter Wing

2021 ◽  
Vol 24 (5) ◽  
pp. 467-474
Author(s):  
Dongsu Choi
Keyword(s):  
Air Force ◽  
Limit Load ◽  
Structural Safety ◽  
Element Analysis ◽  
Calculated Stress ◽  
Safety Margins ◽  
Shape Selection ◽  
Mechanical Fastening ◽  
Crack Defect ◽  
Selection Of

A study on optimal shape selection of a mechanical fastening for the repair of crack defect of ROK Air Force F-5 fighter wing was conducted. The crack defect occurred in the spar of the wing, and the technical manual does not specify the repair method. However, ROK Air Force decided to develop a repair technology for this defect in consideration of various logistic conditions. Three repair shapes for the proper repair were devised and the finite element analysis was performed to examine the structural safety of these three connection members. As a result of the structural safety review, two connection members except one were structurally safe with safety margins over zero because the calculated stress values were at or below the yield strength level. Therefore, two connection members were determined to be able to use for repair under the condition that the aircraft operated within the design limit load. The results of this study would be very useful if the same defect occurs in long-term aircraft operated by the ROK Air Force.

scholarly journals Effect of single tube sections on the structural safety of Chinese solar greenhouse skeletons

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Xingan Liu ◽  
Zhenkun Li ◽  
Lei Zhang ◽  
Yu Liu ◽  
Yiming Li ◽  
...  
Keyword(s):  
Material Selection ◽  
Selection Process ◽  
Load Condition ◽  
Structural Features ◽  
Structural Safety ◽  
Element Analysis ◽  
Cross Sectional ◽  
Single Tube ◽  
The Impact ◽  
Selection Of

AbstractIn recent years, the use of single-tube skeletons for the construction of Chinese solar greenhouses has increased. As a consequence, during the selection of the construction materials, the safety of these structures has become an important issue. The single tube section has various forms, but there is no scientific theory to guide the selection process. To the best of our knowledge, the scientific analysis of the impact of single pipe cross section on the safety of greenhouse skeleton has not been addressed so far. In this context, the finite element analysis software was used to calculate and analyze the stress elements, displacement of round tube, Ω tube, elliptic tube and square tube under the same load conditions. We used the Chinese Standard values as a reference and analyzed structural features of different sizes and thicknesses of the greenhouse steel skeleton sections under non-uniform snow load. The results showed that, under the same load condition, the maximum stress in the four skeleton materials was all located at the connection of the transverse tension bar and the front roof. In addition, under same load condition, the greenhouse skeleton with elliptic tube presented the smallest cross-sectional displacement between the different materials tested. The effect of increasing the size of the greenhouse frame was better than that of increasing the greenhouse material thickness. All this work will provide theoretical guidance to the material selection of this structure.

Evaluation of Limit Load Analysis Methods Applied to High Temperature Design: Part 1 — Consistent Material Modeling

2014 ◽  
Author(s):  
Dave Dewees ◽  
Rahul Jain
Keyword(s):  
Elevated Temperature ◽  
Failure Modes ◽  
Limit Load ◽  
Material Model ◽  
Element Analysis ◽  
Allowable Stresses ◽  
Safety Margins ◽  
Advanced Analysis ◽  
Load Analysis ◽  
Pressure Part

Design-by-Rule codes (i.e. ASME Section I, EN 12952) already exist for elevated temperature (creep) design and have been successfully used for decades; however, there is motivation to optimize designs, or to assess non-standard ones. Limit Load Analysis (LLA) is the simplest advanced analysis method, and a powerful and widely-used tool for establishing compliance with required pressure part safety margins for operation at temperatures below the creep range. However, there is no direct relationship between LLA and elevated temperature allowable stresses and failure modes, such that the basic LLA methods or results must be manipulated in some way to be generally meaningful. With this in mind, review of proposed elevated temperature LLA methods (which are discussed in Part 2 of this work) by comparison to detailed transient inelastic finite element analysis allows for rigorous assessment of simplifications. Specification of an elevated temperature material model that is consistent with traditional allowable stresses for the detailed analysis is described in this paper (Part 1), and the material model and simplified methods are applied to the case of a typical steam header in the next (Part 2). Paper published with permission.

scholarly journals The research of dynamic impacts on the hydraulic structure foundation base, transformed in the process of accident recovery

2018 ◽  
Vol 251 ◽  
pp. 04040
Author(s):  
Zaven Ter-Martirosyan ◽  
Ivan Luzin
Keyword(s):  
Field Experiments ◽  
Dynamic Properties ◽  
Soil Parameters ◽  
Experimental Site ◽  
Element Analysis ◽  
The Finite Element Analysis ◽  
Foundation Base ◽  
Dynamic Impacts ◽  
Scale Experiment ◽  
Selection Of

The article presents the results of a comprehensive research of the dynamic impacts on a modified base. The modified base was obtained as a result of compensatory injection at the experimental site for the accident recovery at the hydraulic engineering structure. The complex study of the dynamic impacts includes special laboratory tests to determine the soil parameters, the finite element analysis of the experimental site, taking into account the dynamic properties, the selection of the necessary equipment for field experiments based on the numerical solution results, a full-scale experiment with the measurement of the foundation sediments of the experimental site.

scholarly journals Shape Selection of Surface-Bound Helical Filaments: Biopolymers on Curved Membranes

2016 ◽  
Vol 111 (7) ◽  
pp. 1575-1585 ◽  
Author(s):  
David A. Quint ◽  
Ajay Gopinathan ◽  
Gregory M. Grason
Keyword(s):  
Shape Selection ◽  
Curved Membranes ◽  
Selection Of

Seismic Risk Evaluation of Retrofitted Reinforced Concrete Buildings Utilizing Base Isolation and Considering Mainshock-Aftershock

2013 ◽  
Vol 671-674 ◽  
pp. 1372-1375
Author(s):  
Rui Long Han ◽  
Yue Li
Keyword(s):  
Seismic Risk ◽  
Risk Evaluation ◽  
Base Isolation ◽  
Seismic Hazards ◽  
Nonlinear Finite Element ◽  
Structural Safety ◽  
Seismic Fragility ◽  
Rc Frame ◽  
Actual Situation ◽  
Element Analysis

The insufficient consideration of seismic risk caused hidden danger for structural safety in many areas. A promising retrofit method for these structures is base isolation. In order to evaluate the effectiveness of this approach, a hypothetical RC frame based on actual situation is designed to be retrofitted using base isolation. Then, seismic fragilities for both un-retrofitted and isolated frames are analyzed, utilizing the results obtained from nonlinear finite-element analysis. The ground motion of the analysis contains 22 earthquake motions, and the results of considering mainshock-aftershock and those of considering only mainshock are compared. The study proves the well designed base isolation can reduce the seismic fragility of the RC frame effectively, and the exclusive consideration of mainshock will underestimate the seismic hazards for structures.

Limit Load Analysis of Cracked Components Using the Reference Volume Method

2006 ◽  
Vol 129 (3) ◽  
pp. 391-399 ◽  
Author(s):  
R. Adibi-Asl ◽  
R. Seshadri
Keyword(s):  
Elastic Modulus ◽  
Three Dimensional ◽  
Local Limit ◽  
Limit Load ◽  
Multiple Cracks ◽  
Element Analysis ◽  
Limit Loads ◽  
Integrity Assessment ◽  
Reference Volume ◽  
Volume Method

Cracks and flaws occur in mechanical components and structures, and can lead to catastrophic failures. Therefore, integrity assessment of components with defects is carried out. This paper describes the Elastic Modulus Adjustment Procedures (EMAP) employed herein to determine the limit load of components with cracks or crack-like flaw. On the basis of linear elastic Finite Element Analysis (FEA), by specifying spatial variations in the elastic modulus, numerous sets of statically admissible and kinematically admissible distributions can be generated, to obtain lower and upper bounds limit loads. Due to the expected local plastic collapse, the reference volume concept is applied to identify the kinematically active and dead zones in the component. The Reference Volume Method is shown to yield a more accurate prediction of local limit loads. The limit load values are then compared with results obtained from inelastic FEA. The procedures are applied to a practical component with crack in order to verify their effectiveness in analyzing crack geometries. The analysis is then directed to geometries containing multiple cracks and three-dimensional defect in pressurized components.

Limit Loads for Laterally Loaded I-Section Beams With Consideration of Shear

2003 ◽  
Vol 47 (02) ◽  
pp. 83-91
Author(s):  
L. Belenkiy ◽  
Y. Raskin
Keyword(s):  
Physical Model ◽  
Limit Load ◽  
Nonlinear Finite Element ◽  
Shear Forces ◽  
Element Analysis ◽  
Limit Loads ◽  
Closed Form Solutions ◽  
Engineering Technique ◽  
Laterally Loaded ◽  
The Web

The paper examines an effect of shear forces on limit load for I-section beams carrying later alloads. The problem is solve don the basis of a physical model, which enables one to take into account the effect of a resistance of beam flanges to the plastic shears train in the web of the beam. The physical model for the evaluation of limit loads was veriŽed using nonlinear finite element analysis. An engineering technique for the calculation of limit loads for shiphull beams subjected to large shear forces was developed using this model. As illustrative examples, the paper shows the application of the proposed technique to obtain closed-form solutions for the prediction of limit loads.

Selection of the Optimal Structural Design of a Spar Composite Wing

2021 ◽  
pp. 90-99
Author(s):  
O.V. Tatarnikov ◽  
W.A. Phyo ◽  
Lin Aung Naing
Keyword(s):  
Optimal Design ◽  
Element Analysis ◽  
Minimal Weight ◽  
Wing Structures ◽  
Optimization Parameters ◽  
Nonlinear Static ◽  
Wing Structure ◽  
Pareto Method ◽  
Selection Of ◽  
Composite Wing

This paper describes a method for optimizing the design of a spar-type composite aircraft wing structure based on multi-criterion approach. Two types of composite wing structures such as two-spar and three-spar ones were considered. The optimal design of a wing frame was determined by the Pareto method basing on three criteria: minimal weight, minimal wing deflection, maximal safety factor and minimal weight. Positions of wing frame parts, i.e. spars and ribs, were considered as optimization parameters. As a result, an optimal design of a composite spar-type wing was proposed. All the calculations necessary to select the optimal structural and design of the spar composite wing were performed using nonlinear static finite element analysis in the FEMAP with NX Nastran software package.

scholarly journals Effect of Ovality in Inlet Pigtail Pipe Bends Under Combined Internal Pressure and In-Plane Bending for Ni-Fe-Cr B407 Material

2017 ◽  
Vol 62 (3) ◽  
pp. 1881-1887
Author(s):  
P. Ramaswami ◽  
P. Senthil Velmurugan ◽  
R. Rajasekar
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Internal Pressure ◽  
Limit Load ◽  
Outer Radius ◽  
Factor H ◽  
Geometrical Shape ◽  
Element Analysis ◽  
Pipe Bend ◽  
Plane Bending

Abstract The present paper makes an attempt to depict the effect of ovality in the inlet pigtail pipe bend of a reformer under combined internal pressure and in-plane bending. Finite element analysis (FEA) and experiments have been used. An incoloy Ni-Fe-Cr B407 alloy material was considered for study and assumed to be elastic-perfectly plastic in behavior. The design of pipe bend is based on ASME B31.3 standard and during manufacturing process, it is challenging to avoid thickening on the inner radius and thinning on the outer radius of pipe bend. This geometrical shape imperfection is known as ovality and its effect needs investigation which is considered for the study. The finite element analysis (ANSYS-workbench) results showed that ovality affects the load carrying capacity of the pipe bend and it was varying with bend factor (h). By data fitting of finite element results, an empirical formula for the limit load of inlet pigtail pipe bend with ovality has been proposed, which is validated by experiments.

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