scholarly journals Numerical Analysis Of Buckling Of Von Mises Planar Truss

2015 ◽  
Vol 15 (2) ◽  
Author(s):  
Martin Kalina
Keyword(s):  
Discrete Model ◽  
Computational Algorithm ◽  
Vertical Displacement ◽  
Critical Force ◽  
Initial Shape ◽  
Geometric Imperfection ◽  
Structure Deformation ◽  
Asymmetric Effects ◽  
Steel Truss ◽  
Von Mises

Abstract A computational algorithm of a discrete model of von Mises planar steel truss is presented. The structure deformation is evaluated by seeking the minimal potential energy. The critical force invented by mathematical solution was compared with solution by computer algorithm. Symmetric and asymmetric effects of initial shape of geometric imperfection of axis of struts are used in model. The shapes of buckling of von Mises planar truss of selected vertical displacement of top joint are shown.

Poisson Ratio Effects on the Von Mises and Maximum Shear Stresses in Cylindrical Contacts

2005 ◽  
Author(s):  
Itzhak Green
Keyword(s):  
Shear Stress ◽  
Poisson Ratio ◽  
Unit Length ◽  
Maximum Shear Stress ◽  
Critical Force ◽  
Von Mises Stress ◽  
Maximum Pressure ◽  
Shear Stresses ◽  
Wide Range ◽  
Von Mises

This work determines the location of the greatest elastic distress in cylindrical contacts based upon the distortion energy and the maximum shear stress theories. The ratios between the maximum pressure, the von Mises stress, and the maximum shear stress are determined and fitted by empirical formulations for a wide range of Poisson ratios, which represent material compressibility. Some similarities exist between cylindrical and spherical contacts, where for many metallic materials the maximum von Mises or shear stresses emerge beneath the surface. However, if any of the bodies in contact is excessively compressible the maximum von Mises stress appears at the surface. That transitional Poisson ratio is found. The critical force per unit length that causes yielding onset, along with its corresponding interference and half-width contact are derived.

scholarly journals On the Applicability of Stereological Methods for the Modelling of a Local Plastic Deformation in Grained Structure: Mathematical Principles

Crystals ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 697
Author(s):  
Stanislav Minárik ◽  
Maroš Martinkovič
Keyword(s):  
Structural Changes ◽  
Local Deformation ◽  
Cross Sectional ◽  
Initial Shape ◽  
Structure Deformation ◽  
Sectional Plane ◽  
Single Grain ◽  
Grain Surface ◽  
Local Plastic Deformation ◽  
Structure Orientation

Analysis of systems and structures from their cross-sectional images finds applications in many branches. Therefore, the question of content, quantity, and accuracy of information obtained from various techniques based on cross-sectional views of structures is particularly important. Application of conventional techniques for two-dimensional imaging on the analysis of structure from a cross-sectional image is limited. The reason for this limitation is the fact that these techniques use a fixed cross-sectional plane and therefore cannot check the 3D structural changes caused by deformation. Geometric orientation of a grained structure must be considered when data, scanned from a cross section, is processed in order to obtain information about local deformation in this structure. The so-called degree of structure orientation in 3D can be estimated experimentally from the cross-sectional image of the structure by the statistical (Saltykov) method of oriented testing lines. Subsequently if the correlation between orientation and deformation were to be known a detailed map of local deformation in the structure could be revealed. Unfortunately, exact theoretical works dealing with the assessment of local deformation by means of change of structure orientation in 3D are still missing. Our work seeks to partially remove this shortcoming. In our work we are interested in how the transformation of the image of a grained structure in a cross-sectional plane reflects structure deformation. An initial shape of grains is assumed which is transformed into a deformed shape by analytic calculation. We present brief mathematical derivations aimed at the problem of single grain-surface area deformation. The main goal of this work led to the design of a computationally low consuming procedure for quantification of local deformation in a grained structure based on the distortion of the image of this structure in a cross-sectional view.

scholarly journals Ultimate Strength Assessment of Steel-Welded Hemispheres under External Hydrostatic Pressure

2021 ◽  
Author(s):  
Sang-Rai Cho ◽  
Teguh Muttaqie ◽  
Seung Hyun Lee ◽  
Jaewoo Paek ◽  
Jung Min Sohn
Keyword(s):  
Hydrostatic Pressure ◽  
Load Capacity ◽  
External Hydrostatic Pressure ◽  
Ultimate Load Capacity ◽  
Initial Shape ◽  
Strength Assessment ◽  
Geometric Imperfection ◽  
Collapse Pressure ◽  
Hemispherical Shells ◽  
Shape Imperfection

AbstractThis paper focusses on steel-welded hemispherical shells subjected to external hydrostatic pressure. The experimental and numerical investigations were performed to study their failure behaviour. The model was fabricated from mild steel and made through press forming and welding. We therefore considered the effect of initial shape imperfection, variation of thickness and residual stress obtained from the actual structures. Four hemisphere models designed with R/t from 50 to 130 were tested until failure. Prior to the test, the actual geometric imperfection and shell thickness were carefully measured. The comparisons of available design codes (PD 5500, ABS, DNV-GL) in calculating the collapse pressure were also highlighted against the available published test data on steel-welded hemispheres. Furthermore, the nonlinear FE simulations were also conducted to substantiate the ultimate load capacity and plastic deformation of the models that were tested. Parametric dependence of the level of sphericity, varying thickness and residual welding stresses were also numerically considered in the benchmark studies. The structure behaviour from the experiments was used to verify the numerical analysis. In this work, both collapse pressure and failure mode in the numerical model were consistent with the experimental model.

scholarly journals Stability of a Micro-Heterogeneous Plate Band

2015 ◽  
Vol 61 (4) ◽  
pp. 91-106
Author(s):  
M. Chalecki ◽  
G. Jemielita
Keyword(s):  
Stiffness Matrix ◽  
Computational Algorithm ◽  
Individual Cell ◽  
Variable Stiffness ◽  
Critical Force ◽  
The Finite Element Method ◽  
Critical Buckling Force ◽  
Support Conditions ◽  
Heterogeneous Plate ◽  
Number Of Cells

The paper presents a certain way which determines the critical buckling force for a micro-heterogeneous FGM plate band. A stiffness matrix of an individual cell of such band, different for various cells, has been determined. The obtained matrix can also be treated as a variable stiffness matrix of a “superelement” in the Finite Element Method. A computational algorithm for the critical force as well as the way of testing of its correctness has also been presented. The results obtained for various support conditions have been compared to the values known from the literature. The influence of the number of cells on the critical buckling force has been investigated.

Analisa Non-Linier Pada Mekanisme Keruntuhan Jembatan Rangka Baja Tipe Pratt

2017 ◽  
Vol 1 (2) ◽  
pp. 68
Author(s):  
Heri Istiono ◽  
Jaka Propika
Keyword(s):  
Static Load ◽  
Pushover Analysis ◽  
Vertical Displacement ◽  
Bridge Structure ◽  
Steel Truss Bridge ◽  
Bridge Collapse ◽  
Steel Truss ◽  
Load Pattern ◽  
Existing Bridges ◽  
Truss Bridge

Steel truss bridge collapse often occurs, both in Indonesia and in other countries. As a result of the collapse of the bridge is in addition to the casualties also losses from the financial aspects. This collapse caused due to various factors, one of them because of a decrease in the strength of the bridge structure. To minimize required maintenance of the bridge's collapse and to facilitate the maintenance of one of them must be known failure mechanisms existing bridges. In the analysis of this collapse, will be modeled steel truss bridge pratt’s type with long spans is 60 meters. Analysis of the collapse of the steel truss bridge's, utilizing a pushover analysis to analyze the behavior of the bridge structure. Pushover analysis done with give vertical static load pattern at the structure, next gradually increase by a factor until one vertical displacement target of the reference point is reached. The study shows that at model singe span failure occurred on the chord on mid span. The performance level of structure shows all models of bridges in the state are IO, this case based on the target displacement FEMA 356 and the actual ductility occurs in all models of bridges is compliant with SNI 2833-2008.

scholarly journals Investigating the Effect of Nonrigid Connectors on the Success of Tooth-and-Implant-Supported Fixed Partial Prostheses in Maxillary Anterior Region: A Finite Element Analysis (FEA)

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Ramin Mosharraf ◽  
Paria Molaei ◽  
Amirhossein Fathi ◽  
Sabire Isler
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Applied Stress ◽  
Vertical Displacement ◽  
Anterior Region ◽  
Von Mises Stress ◽  
Element Analysis ◽  
Vertical Loading ◽  
3D Fea ◽  
Von Mises

Objective. This study was designed to assess the effect of nonrigid connectors (NRCs) and their location in the success of tooth-and-implant-supported fixed prostheses in the maxillary anterior region by finite element analysis (FEA). Materials and Methods. Three 3D FEA models were designed, presuming maxillary lateral incisor and canine to be extracted. Implant (replacing canine), abutment, bone (spongious and cortical), central incisor (containing dentin, root cement, gutta-percha, and casting post and core), periodontal ligament, and three three-unit cemented PFM prostheses (a rigid one and two nonrigid) were modeled. The NRC was once in the tooth side and once in the implant side. The prostheses were loaded twice: 250N to the incisal edges (0° to the long axis) and 200 N to the cingula (45° to the long axis). The von-Mises stress and vertical displacement were analyzed. Results. Under both vertical and oblique loadings, the rigid model presented the highest stress. Under vertical loading, the NRC caused a significant decrease in the applied stress to the prosthesis, bone, implant, and tooth. Locating the NRC in the tooth side decreased the applied stress to the prosthesis and NRC. Under oblique loading, prosthesis and implant tolerated less stress in the presence of an NRC. Placing the NRC in the tooth side resulted in the least stress in all of the components except for porcelain and patrix. Vertical displacement of the tooth apex was approximately equal in all models. Conclusion. Using an NRC on the tooth side is the most efficient method in reducing the applied stress to prosthesis, implant, tooth, and bone. The amount of intrusion is not dependent on using an NRC or not.

scholarly journals Numerical Simulation of Tire Reinforced Sand behind Retaining Wall Under Earthquake Excitation

2014 ◽  
Vol 4 (2) ◽  
pp. 605-611 ◽  
Author(s):  
A. Lazizi ◽  
H. Trouzine ◽  
A. Asroun ◽  
F. Belabdelouhab
Keyword(s):  
Retaining Wall ◽  
Horizontal Displacement ◽  
Vertical Displacement ◽  
Retaining Walls ◽  
Von Mises Stress ◽  
Earthquake Excitation ◽  
Element Analysis ◽  
Reinforced Sand ◽  
Waste Tire ◽  
Von Mises

This paper studies the numerical simulations of retaining walls supporting tire reinforced sand subjected to El Centro earthquake excitation using finite element analysis. For this, four cases are studied: cantilever retaining wall supporting sand under static and dynamical excitation, and cantilever retaining wall supporting waste tire reinforced sand under static and dynamical excitation. Analytical external stability analyses of the selected retaining wall show that, for all four cases, the factors of safety for base sliding and overturning are less than default minimum values. Numerical analyses show that there are no large differences between the case of wall supporting waste tire reinforced sand and the case of wall supporting sand for static loading. Under seismic excitation, the higher value of Von Mises stress for the case of retaining wall supporting waste tire reinforced sand is 3.46 times lower compared to the case of retaining wall supporting sand. The variation of horizontal displacement (U1) and vertical displacement (U2) near the retaining wall, with depth, are also presented.

Flexible bar compression test

2021 ◽  
Author(s):  
A.V. Egorov
Keyword(s):  
Initial Imperfection ◽  
Critical Force ◽  
Theoretical Research ◽  
Design Calculation ◽  
Special Equipment ◽  
Euler Formula ◽  
Initial Shape ◽  
Analysis Methodology ◽  
Steel Bar ◽  
Geometric Boundary

The article considers experimental and theoretical research of longitudinal stability of a flexible steel bar design under axial compression. The bar is a flat thin-walled element, pivotally fixed at the ends. The experimental study was carried out on a Zwick/Roell Z100 installation using special equipment that simulates geometric boundary conditions. During the loading process, a diagram of the deformation of a real bar with initial shape imperfections was automatically constructed. The experimental critical force was determined from the deformation diagram. This force was compared with the critical forces obtained from calculations using two schemes: the Euler formula and the dynamic analysis methodology. In the second scheme, in contrast to the first one, the initial imperfection, established by the measurements of the tested structure, was taken into account. The design calculation errors for both schemes were determined.

Elastic Buckling and Post-Buckling of Von Mises Planar Trusses

2015 ◽  
Vol 769 ◽  
pp. 49-54
Author(s):  
Martin Kalina ◽  
Zdenek Kala ◽  
Petr Frantik
Keyword(s):  
Vertical Displacement ◽  
Mathematical Concept ◽  
Structural Deformation ◽  
Incremental Method ◽  
Critical Effect ◽  
Post Buckling ◽  
Load Action ◽  
The Stability ◽  
The Moment ◽  
Von Mises

The article deals with the computational model of an elastic von Mises planar truss. The description of a mathematical concept, which is intended for the creation of computational programmes based on a finite number of segments, is presented. The mathematical solution is suitable for the analysis of load-deflection curves. Structural deformation is evaluated by seeking the minimal potential energy. The article examines the effects of change in the vertical displacement of the top joint on strut axes. The step by step incremental method is used in combination with the Newton-Raphson method. The presented study is aimed at the evaluation of the force in the bifurcation point, which determines the moment when loading of the model causes passing from the pre-critical effect (attainment of maximum vertical load action) to the post-critical effect. Symmetric and asymmetric initial axis imperfections are considered and relevant symmetric and asymmetric shapes of buckling are identified. The stability problem of the von Mises truss is discussed in connection with the random effects of imperfections.

Tensile Failure of 55-Nitinol Wire

1975 ◽  
Vol 33 ◽  
pp. 46-47
Author(s):  
F. I. Grace
Keyword(s):  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Stoichiometric Composition ◽  
Tensile Failure ◽  
Initial State ◽  
Initial Shape ◽  
Nitinol Wire ◽  
Cscl Type ◽  
Shear Transformation

An interest in NiTi alloys with near stoichiometric composition (55 NiTi) has intensified since they were found to exhibit a unique mechanical shape memory effect at the Naval Ordnance Laboratory some twelve years ago (thus refered to as NITINOL alloys). Since then, the microstructural mechanisms associated with the shape memory effect have been investigated and several interesting engineering applications have appeared.The shape memory effect implies that the alloy deformed from an initial shape will spontaneously return to that initial state upon heating. This behavior is reported to be related to a diffusionless shear transformation which takes place between similar but slightly different CsCl type structures.

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