scholarly journals Mechanical Behavior of Steel Pipe Bends: An Overview

2016 ◽  
Vol 138 (4) ◽  
Author(s):  
Spyros A. Karamanos
Keyword(s):  
Experimental Data ◽  
Finite Element ◽  
Mechanical Behavior ◽  
Cross Section ◽  
Steel Pipe ◽  
Buried Pipelines ◽  
Cross Sectional ◽  
Out Of Plane ◽  
Bending Capacity ◽  
Bending Loading

An overview of the mechanical behavior of steel pipe (elbows) is offered, based on previously reported analytical solutions, numerical results, and experimental data. The behavior of pipe bends is characterized by significant deformations and stresses, quite higher than the ones developed in straight pipes with the same cross section. Under bending loading (in-plane and out-of-plane), the main feature of the response is cross-sectional ovalization, which influences bending capacity and is affected by the level of internal pressure. Bends subjected to cyclic in-plane bending exhibit fatigue damage, leading to base metal cracking at the elbow flank. Using advanced finite-element tools, the response of pipe elbows in buried pipelines subjected to ground-induced actions is also addressed, with emphasis on soil–pipeline interaction. Finally, the efficiency of special-purpose finite elements for modeling pipes and elbows is briefly discussed.

Stress concentration factors for the torsion of curved beams of arbitrary cross-section

2006 ◽  
Vol 220 (12) ◽  
pp. 1709-1726 ◽  
Author(s):  
R E Cornwell
Keyword(s):  
Finite Element ◽  
Stress Concentration ◽  
Cross Section ◽  
Cross Sections ◽  
Shear Stresses ◽  
Curved Beams ◽  
Finite Element Implementation ◽  
Out Of Plane ◽  
Concentration Factors ◽  
Stress Concentration Factors

There are numerous situations in machine component design in which curved beams with cross-sections of arbitrary geometry are loaded in the plane of curvature, i.e. in flexure. However, there is little guidance in the technical literature concerning how the shear stresses resulting from out-of-plane loading of these same components are effected by the component's curvature. The current literature on out-of-plane loading of curved members relates almost exclusively to the circular and rectangular cross-sections used in springs. This article extends the range of applicability of stress concentration factors for curved beams with circular and rectangular cross-sections and greatly expands the types of cross-sections for which stress concentration factors are available. Wahl's stress concentration factor for circular cross-sections, usually assumed only valid for spring indices above 3.0, is shown to be applicable for spring indices as low as 1.2. The theory applicable to the torsion of curved beams and its finite-element implementation are outlined. Results developed using the finite-element implementation agree with previously available data for circular and rectangular cross-sections while providing stress concentration factors for a wider variety of cross-section geometries and spring indices.

Exact Solution for Bending of Shape Memory Alloy Superelastic Beams

2011 ◽  
Author(s):  
Ahmadreza Eshghinejad ◽  
Mohammad Elahinia
Keyword(s):  
Experimental Data ◽  
Exact Solution ◽  
Finite Element ◽  
Numerical Methods ◽  
Shape Memory ◽  
Cross Section ◽  
Analytical Approach ◽  
Thermomechanical Behavior ◽  
Linear Distribution ◽  
Mode Of Application

Bending is a common mode of application and operation of shape memory alloys (SMA). So far the coupled thermomechanical behavior of these alloys have been modeled with numerical methods such as finite element. The issue in developing exact solutions for a SMA beam in bending is because of the distributed and hysteric stress-strain profile. In this paper an analytical approach is developed to find the exact solution for the displacement due to the applied force on the SMA superelastic beam. The approach is based on the assumption of linear distribution of strain along the height of a cross section in the beam. The solution is validated by experimental data and the results of the solution for a superelastic beams for different cases are illustrated.

scholarly journals Influence of nickel-titanium rotary systems with varying cross-sectional, pitch, and rotational speed on deflection and cyclic fatigue: a finite element analysis study

2021 ◽  
Vol 41 ◽  
pp. 05005
Author(s):  
Wignyo Hadriyanto ◽  
Lukita Wardani ◽  
Christina Nugrohowati ◽  
Ananto Alhasyimi ◽  
Rachmat Sriwijaya ◽  
...  
Keyword(s):  
Finite Element ◽  
Cross Section ◽  
Rotational Speed ◽  
Cyclic Fatigue ◽  
Nickel Titanium ◽  
Element Analysis ◽  
Cross Sectional ◽  
Rotary Instruments ◽  
Section Design ◽  
Sectional Shape

The effectiveness of endodontic file preparation depends, among others, on the material, geometric shape, and the drive system. This study aimed to analyze the effect of cross-sectional, pitch, and rotational speed on cyclic fatigue and deflection of NiTi files using finite element analyses. A total of 18 NiTi endodontic rotary instruments ProTaper Gold F2 #25.08 and Hyflex CM #25.04 (n=9) modeling were designed using Autodesk software. Subjects were divided into two groups, the design group of square and convex triangles. Static simulation was then carried out to each group with force on the instrument’s tip by 1N, 2N, and 3N. The file’s cycling fatigue was analyzed at rotating speeds of 200 rpm, 300 rpm, and 400. The data were analyzed by using the three-way Analysis of variance (ANOVA) test followed by LSD (p< 0.05). The results showed the cross-sectional shape and force effect on the deflection value and cyclic fatigue received by the endodontic files (p< 0.05). The convex triangle design presented the lowest cyclic fatigue than square. The convex triangular cross-section design showed a higher deflection value than the square cross-section design.

Saint-Venant Decay Rates for the Rectangular Cross Section Rod

2004 ◽  
Vol 71 (3) ◽  
pp. 429-433 ◽  
Author(s):  
N. G. Stephen ◽  
P. J. Wang
Keyword(s):  
Finite Element ◽  
Aspect Ratio ◽  
Transfer Matrix ◽  
Cross Section ◽  
Cross Sections ◽  
Rectangular Cross Section ◽  
Decay Rates ◽  
Elastic Rod ◽  
Cross Sectional ◽  
Element Transfer

A finite element-transfer matrix procedure developed for determination of Saint-Venant decay rates of self-equilibrated loading at one end of a semi-infinite prismatic elastic rod of general cross section, which are the eigenvalues of a single repeating cell transfer matrix, is applied to the case of a rectangular cross section. First, a characteristic length of the rod is modelled within a finite element code; a superelement stiffness matrix relating force and displacement components at the master nodes at the ends of the length is then constructed, and its manipulation provides the transfer matrix, from which the eigenvalues and eigenvectors are determined. Over the range from plane stress to plane strain, which are the extremes of aspect ratio, there are always eigenmodes which decay slower than the generalized Papkovitch-Fadle modes, the latter being largely insensitive to aspect ratio. For compact cross sections, close to square, the slowest decay is for a mode having a distribution of axial displacement reminiscent of that associated with warping during torsion; for less compact cross sections, slowest decay is for a mode characterized by cross-sectional bending, caused by self-equilibrated twisting moment.

scholarly journals Fiber Bridging Induced Toughening Effects on the Delamination Behavior of Composite Stiffened Panels under Bending Loading: A Numerical/Experimental Study

Materials ◽  
2019 ◽  
Vol 12 (15) ◽  
pp. 2407 ◽  
Author(s):  
Angela Russo ◽  
Mauro Zarrelli ◽  
Andrea Sellitto ◽  
Aniello Riccio
Keyword(s):  
Experimental Data ◽  
Fracture Toughness ◽  
Composite Structures ◽  
Numerical Procedure ◽  
Research Activity ◽  
Stiffened Panels ◽  
Mode I Fracture Toughness ◽  
Fiber Bridging ◽  
Out Of Plane ◽  
Bending Loading

In this paper, a research activity, focused on the investigation of new reinforcements able to improve the toughness of composite materials systems, is introduced. The overall aim is to delay the delamination propagation and, consequently, to increase the carrying load capability of composite structures by exploiting the fiber bridging effects. Indeed, the influence of fiber bridging related Mode I fracture toughness (GIc) values on the onset and propagation of delaminations in stiffened composite panels, under three-point bending loading conditions, have been experimentally and numerically studied. The investigated stiffened panels have been manufactured by using epoxy resin/carbon fibers material systems, characterized by different GIc values, which can be associated with the material fiber bridging sensitivity. Experimental data, in terms of load and delaminated area as a function of the out-of-plane displacements, have been obtained for each tested sample. Non-Destructive Inspection (NDI) has been performed to identify the debonding extension and position. To completely understand the evolution of the delamination and its dependence on the material characteristics, experiments have been numerically simulated using a newly developed robust numerical procedure for the delamination growth simulation, able to take into account the influence of the fracture toughness changes, associated with the materials’ fiber bridging sensitivity. The combined use of numerical results and experimental data has allowed introducing interesting considerations of the capability of the fiber bridging to substantially slow down the evolution of the debonding between skin and reinforcements in composite stiffened panels.

scholarly journals Coupled Bending-Bending-Torsion Vibration of a Pre-Twisted Beam with Aerofoil Cross-Section by the Finite Element Method

2003 ◽  
Vol 10 (4) ◽  
pp. 223-230
Author(s):  
Bulent Yardimoglu ◽  
Daniel J. Inman
Keyword(s):  
Finite Element ◽  
Cross Section ◽  
Degrees Of Freedom ◽  
Element Model ◽  
Higher Order ◽  
Coupling Coefficients ◽  
Cross Sectional ◽  
Torsion Vibration ◽  
Proper Order ◽  
Proposed Model

The present study deals with a finite element model for coupled bending-bending-torsion vibration analysis of a pretwisted Timoshenko beam with varying aerofoil cross-section. The element derived in this paper has two nodes, with seven degrees of freedom at each node. The nodal variables are transverse displacements, cross-section rotations and the shear angles in two planes and torsional displacement. The advantage of the present element is the exclusion of unnecessary derivatives of fundamental nodal variables, which were included to obtain invertable square matrix by other researchers, by choosing proper displacement functions and using relationship between cross-sectional rotation and the shear deformation. Element stiffness and mass matrices are developed from strain and kinetic energy expressions by assigning proper order polynomial expressions for cross-section properties and considering higher order coupling coefficients. The correctness of the present model is confirmed by the experimental results available in the literature. Comparison of the proposed model results with those in the literature indicates that a faster convergence is obtained. The results presented also provide some insights in the formulation by clearly indicating that higher order coupling terms have considerable influence on the natural frequencies.

Finite Element Modelling of Buckling Restrained Braces under Combined In-Plane and Out-of-Plane Loading

2018 ◽  
Vol 763 ◽  
pp. 908-915
Author(s):  
Jian Cui ◽  
Chin Long Lee ◽  
Gregory A. MacRae
Keyword(s):  
Finite Element ◽  
Energy Dissipation ◽  
Cross Section ◽  
Finite Element Modelling ◽  
Circular Cross Section ◽  
Element Model ◽  
Buckling Restrained Braces ◽  
Out Of Plane ◽  
Simulation Results ◽  
Insight Into

During earthquakes, buckling restrained braces (BRBs) are likely subjected to both in-plane (INP) and out-of-plane (OOP) loadings simultaneously, therefore, BRBs are required to act robustly under combined INP and OOP loading. It is believed that the OOP loading will reduce the energy dissipation ability of BRBs. The intent of this study is to numerically investigate the performance of BRBs under combined INP and OOP loading with a finite element model of BRB with circular cross-section. Restraining concrete within the BRB is modeled as connector elements in the model and is proven to be an effective way. Simulation results show that the performance of BRBs under combined INP and OOP loading is not as good as that under the INP loading only and the energy dissipation ability is decreased by about 15% when the magnitude of OOP loading is equal to that of INP loading. Furthermore, the results give a deeper insight into the behaviour of BRBs under different combined OOP and INP loading histories.

scholarly journals Shape Optimization of Bone-Bonding Subperiosteal Devices with Finite Element Analysis

2017 ◽  
Vol 2017 ◽  
pp. 1-7
Author(s):  
Takeshi Ogasawara ◽  
Masayoshi Uezono ◽  
Kazuo Takakuda ◽  
Masanori Kikuchi ◽  
Shoichi Suzuki ◽  
...  
Keyword(s):  
Finite Element ◽  
Cross Section ◽  
Bonding Strength ◽  
Clinical Performance ◽  
Rectangular Cross Section ◽  
Optimum Shape ◽  
Bone Surface ◽  
Element Analysis ◽  
Cross Sectional ◽  
Rapid Acquisition

Subperiosteal bone-bonding devices have been proposed for less invasive treatments in orthodontics. The device is osseointegrated onto a bone surface without fixation screws and is expected to rapidly attain a bone-bonding strength that successfully meets clinical performance. Hence, the device’s optimum shape for rapid and strong bone bonding was examined in this study by finite element analyses. First, a stress analysis was performed for a circular rod device with an orthodontic force parallel to the bone surface, and the estimate of the bone-bonding strength based on the bone fracture criterion was verified with the results of an animal experiment. In total, four cross-sectional rod geometries were investigated: circular (Cr), elliptical (El), semicircular (Sc), and rectangular (Rc). By changing the height of the newly formed bone to mimic the progression of new bone formation, the estimation of the bone-bonding strength was repeated for each geometry. The rod with the Rc cross section exhibited the best performance, followed by those with the Sc, El, and Cr cross sections, from the aspects of the rapid acquisition of strength and the strength itself. Thus, the rectangular cross section is the best for rod-like subperiosteal devices for rapid bone bonding.

Wave Propagation Through Soft Tissue: Effect of Material Nonlinearity and Nonuniform Cross–Section

2014 ◽  
Author(s):  
Marcelo F. Valdez ◽  
Balakumar Balachandran
Keyword(s):  
Wave Propagation ◽  
Soft Tissue ◽  
Mechanical Behavior ◽  
Wave Front ◽  
Nonlinear Wave ◽  
Cross Section ◽  
Stress Waves ◽  
Sectional Area ◽  
Longitudinal Stress ◽  
Cross Sectional

A better understanding of the influence of material nonlinearities on the propagation of mechanical stress waves is necessary to generate insights into damage mechanisms of soft tissues subjected to rapid and strong external excitations. In this effort, the authors study the propagation of longitudinal stress waves through soft tissue. Emphasis is placed on the influence of nonlinear material behavior and nonuniform cross–section on the characteristics of the stress–wave propagation. The mechanical behavior of the soft tissue is represented by a nonlinear viscoelastic model that is obtained through a maximum dissipation, thermodynamically consistent construction. The effect of the tissue nonlinear mechanical behavior is studied through asymptotic analysis. Examining the obtained analytical approximation, it is possible to discern nonlinear wave front steepening and the effect of the material dissipation. The effects of a nonuniform cross–sectional area are investigated through numerical simulations. These studies can be applied to understand the effect of geometric features of axons on the propagation of longitudinal stress waves. For example, the diameter of an axon gradually increases near its ends, and varicosities/boutons along the axons represent concentrated cross–sectional area variations. Simulations are carried out to examine various aspects of the nonlinear wave propagation such as wave front steepening. This work can serve as a basis for better understanding the mechanical causes underlying mild traumatic brain injury caused by a head impact or explosive blast waves.

Sign in / Sign up

Export Citation Format

Share Document