Mechanical response of a panel section with a hexagonally tessellated stiffener grid

2016 ◽  
Vol 231 (8) ◽  
pp. 1402-1414
Author(s):  
M Bouazizi ◽  
T Lazghab ◽  
M Soula
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Mechanical Response ◽  
Element Model ◽  
External Loading ◽  
Original Structure ◽  
Hexagonal Grid ◽  
Aircraft Fuselage ◽  
Stiffened Shells ◽  
Analytical Expressions

Stringers are stiffening members of pressurized aircraft fuselage. They provide support to the fuselage’s skin. A new stringer grid concept is proposed for conventional aircraft fuselage. Optimization is used to find the hexagonal grid that best replaces the original while keeping the same total stringer length. A finite element model is built to analyze the optimal hexagonal grid stiffened structure and compare it with the original orthogonally stiffened structure in terms of eigenfrequencies and static response to external loading. The finite element model is validated through Flugge’s analytical expressions for stiffened shells. Results show that the hexagonal grid stiffened structure yields higher eigenfrequencies with stresses and displacements comparable with that of the original structure.

Finite Element Modeling of Selective Laser Melting 316L Stainless Steel Parts for Evaluating the Mechanical Properties

2016 ◽  
Author(s):  
Arman Ahmadi ◽  
Narges Shayesteh Moghaddam ◽  
Mohammad Elahinia ◽  
Haluk E. Karaca ◽  
Reza Mirzaeifar
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Stainless Steel ◽  
Finite Element Model ◽  
Grain Boundaries ◽  
Mechanical Response ◽  
Element Model ◽  
Polycrystalline Materials ◽  
Microstructural Properties ◽  
Laser Melting

Selective laser melting (SLM) is an additive manufacturing technique in which complex parts can be fabricated directly by melting layers of powder from a CAD model. SLM has a wide range of application in biomedicine and other engineering areas and it has a series of advantages over traditional processing techniques. A large number of variables including laser power, scanning speed, scanning line spacing, layer thickness, material based input parameters, etc. have a considerable effect on SLM process materials. The interaction between these parameters is not completely studied. Limited studies on balling effect in SLM, densifications under different processing conditions, and laser re-melting, have been conducted that involved microstructural investigation. Grain boundaries are amongst the most important microstructural properties in polycrystalline materials with a significant effect on the fracture and plastic deformation. In SLM samples, in addition to the grain boundaries, the microstructure has another set of connecting surfaces between the melt pools. In this study, a computational framework is developed to model the mechanical response of SLM processed materials by considering both the grain boundaries and melt pool boundaries in the material. To this end, a 3D finite element model is developed to investigate the effect of various microstructural properties including the grains size, melt pools size, and pool connectivity on the macroscopic mechanical response of the SLM manufactured materials. A conventional microstructural model for studying polycrystalline materials is modified to incorporate the effect of connecting melt pools beside the grain boundaries. In this model, individual melt pools are approximated as overlapped cylinders each containing several grains and grain boundaries, which are modeled to be attached together by the cohesive zone method. This method has been used in modeling adhesives, bonded interfaces, gaskets, and rock fracture. A traction-separation description of the interface is used as the constitutive response of this model. Anisotropic elasticity and crystal plasticity are used as constitutive laws for the material inside the grains. For the experimental verification, stainless steel 316L flat dog bone samples are fabricated by SLM and tested in tension. During fabrication, the power of laser is constant, and the scan speed is changed to study the effect of fabrication parameters on the mechanical properties of the parts and to compare the result with the finite element model.

Fully Coupled Three-Scale Finite Element Model for the Mechanical Response of a New Bio-Inspired Composite

2011 ◽  
Author(s):  
Erick I. Saavedra Flores ◽  
Senthil Murugan ◽  
Michael I. Friswell ◽  
Eduardo A. de Souza Neto
Keyword(s):  
Finite Element ◽  
Magnesium Alloy ◽  
Finite Element Model ◽  
Large Scale ◽  
Mechanical Response ◽  
Volume Fraction ◽  
Element Model ◽  
Crystalline Cellulose ◽  
Gauss Point ◽  
Fully Coupled

This paper proposes a fully coupled three-scale finite element model for the mechanical description of an alumina/magnesium alloy/epoxy composite inspired in the mechanics and architecture of wood cellulose fibres. The constitutive response of the composite (the large scale continuum) is described by means of a representative volume element (RVE, corresponding to the intermediate scale) in which the fibre is represented as a periodic alternation of alumina and magnesium alloy fractions. Furthermore, at a lower scale the overall constitutive behavior of the alumina/magnesium alloy fibre is modelled as a single material defined by a large number of RVEs (the smallest material scale) at the Gauss point (intermediate) level. Numerical material tests show that the choice of the volume fraction of alumina based on those volume fractions of crystalline cellulose found in wood cells results in a maximisation of toughness in the present bio-inspired composite.

A Finite Element Model for Direction-Dependent Mechanical Response to Nanoindentation of Cortical Bone Allowing for Anisotropic Post-Yield Behavior of the Tissue

2010 ◽  
Vol 132 (8) ◽  
Author(s):  
D. Carnelli ◽  
D. Gastaldi ◽  
V. Sassi ◽  
R. Contro ◽  
C. Ortiz ◽  
...  
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Cortical Bone ◽  
Yield Stress ◽  
Bone Tissue ◽  
Mechanical Response ◽  
Experimental Studies ◽  
Element Model ◽  
Yield Behavior ◽  
Constitutive Parameters

A finite element model was developed for numerical simulations of nanoindentation tests on cortical bone. The model allows for anisotropic elastic and post-yield behavior of the tissue. The material model for the post-yield behavior was obtained through a suitable linear transformation of the stress tensor components to define the properties of the real anisotropic material in terms of a fictitious isotropic solid. A tension-compression yield stress mismatch and a direction-dependent yield stress are allowed for. The constitutive parameters are determined on the basis of literature experimental data. Indentation experiments along the axial (the longitudinal direction of long bones) and transverse directions have been simulated with the purpose to calculate the indentation moduli and the tissue hardness in both the indentation directions. The results have shown that the transverse to axial mismatch of indentation moduli was correctly simulated regardless of the constitutive parameters used to describe the post-yield behavior. The axial to transverse hardness mismatch observed in experimental studies (see, for example, Rho et al. [1999, “Elastic Properties of Microstructural Components of Human Bone Tissue as Measured by Nanoindentation,” J. Biomed. Mater. Res., 45, pp. 48–54] for results on human tibial cortical bone) can be correctly simulated through an anisotropic yield constitutive model. Furthermore, previous experimental results have shown that cortical bone tissue subject to nanoindentation does not exhibit piling-up. The numerical model presented in this paper shows that the probe tip-tissue friction and the post-yield deformation modes play a relevant role in this respect; in particular, a small dilatation angle, ruling the volumetric inelastic strain, is required to approach the experimental findings.

Subject-Specific Experimental Validation of a C27 Cervical Spine Finite Element Model

2009 ◽  
Author(s):  
Nicole A. Kallemeyn ◽  
Kiran H. Shivanna ◽  
Anup A. Gandhi ◽  
Swathi Kode ◽  
Nicole M. Grosland
Keyword(s):  
Finite Element ◽  
Cervical Spine ◽  
Finite Element Model ◽  
Experimental Validation ◽  
Element Model ◽  
Fe Analysis ◽  
External Loading ◽  
Computational Simulations ◽  
Angular Rotation ◽  
Subject Specific

Computational simulations of the spine have the ability to quantify both the external (i.e. angular rotation) and internal (i.e. stresses and strains) responses to external loading. This is an advantage over cadaveric bench top studies, which are limited to studying mostly external responses. Finite element (FE) analysis has been used extensively to investigate the behavior of the normal cervical spine in addition to its diseased and degenerated states [1,2].

Prediction of Modal Characteristics due to Design Change

1997 ◽  
Author(s):  
Tong Y. Yi ◽  
Parviz E. Nikravesh
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Stiffness Matrix ◽  
Element Model ◽  
Vibration Characteristics ◽  
Original Structure ◽  
Design Change ◽  
Modal Data ◽  
Modal Characteristics

Abstract This paper presents a method for predicting modal characteristics of a structure that is considered to undergo a design change. It is assumed that for the original structure the modal data is available either as a complete or as an incomplete set. Based on the available modal data and the known data on the design change, this paper discusses methodologies for determining the vibration characteristics of the modified structure. By considering practical situations, the emphasis of this paper is on structures for which a finite element model, and hence a stiffness matrix, is not available.

scholarly journals Is a simplified Finite Element model of the gluteus region able to capture the mechanical response of the internal soft tissues under compression?

2020 ◽  
Vol 71 ◽  
pp. 92-100
Author(s):  
Aurélien Macron ◽  
Hélène Pillet ◽  
Jennifer Doridam ◽  
Isabelle Rivals ◽  
Mohammad Javad Sadeghinia ◽  
...  
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Soft Tissues ◽  
Mechanical Response ◽  
Element Model ◽  
Simplified Finite Element Model

Structural Analysis of Universal Shaft Based on ANSYS

2011 ◽  
Vol 215 ◽  
pp. 244-248
Author(s):  
Fu Qiang Ying ◽  
Ling Dong Wu ◽  
Yi Wang ◽  
Liang Yi Li
Keyword(s):  
Finite Element ◽  
Structural Analysis ◽  
Finite Element Model ◽  
Dynamic Analysis ◽  
Stress Analysis ◽  
Element Model ◽  
Original Structure ◽  
Static Stiffness ◽  
Stiffness Analysis ◽  
Weak Points

Universal shaft is widely used to transfer the torque and rotational movement from the drive shaft to the slave while position of one shaft can be changed. Crack used to appear in the fork part of the universal shaft in tests in a universal company. In order to solve this problem, in this paper, a finite element model of universal shaft was established with the application of Pro/E and ANSYS, and the static stiffness analysis, stress analysis and dynamic analysis were all applied in ANSYS. According to the results, the weak points were found and some improvements on the original structure were made.

The Influences of Complex Impact Conditions on Aircraft Fuselage Crashworthiness

2012 ◽  
Vol 184-185 ◽  
pp. 546-552 ◽  
Author(s):  
Tian Chun Zou ◽  
Xiao Min Zhang ◽  
Hao Lei Mou ◽  
Zhen Yu Feng
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Dynamic Characteristics ◽  
Vertical Velocity ◽  
Element Model ◽  
Roll Angle ◽  
Aircraft Structure ◽  
Aircraft Fuselage ◽  
Acceleration History ◽  
The Impact

In this paper, a certain B737 aircraft fuselage section was used to research the influence of different impact conditions on fuselage dynamic characteristics. A finite element model of fuselage was built up from FS380 to FS500. The impact responses of fuselage subjected to 9.133m/s vertical velocity were analyzed under the conditions of 0° roll angle, 10° left roll angle and combination acceleration. The differences of transformation and acceleration history curves under different conditions were compared. The research results show that the performances of 10° left roll angle will change fuselage transformation and acceleration of seats location, the appears of combination acceleration will increase transformation of floor and decrease acceleration at the seats location. The crashworthiness of aircraft structure can be effectively improved by selecting the appropriate landing way.

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