oalib
Search Results: 1 - 10 of 100 matches for " "
All listed articles are free for downloading (OA Articles)
Page 1 /100
Display every page Item
Comparison of cement pressurisation in flanged and unflanged acetabular cups
Rajarshi Bhattacharya, Fahad G Attar, Sarah Green, Andrew Port
Journal of Orthopaedic Surgery and Research , 2012, DOI: 10.1186/1749-799x-7-5
Abstract: Using a model acetabulum, cement was inserted and pressurised followed by cup insertion and pressurisation. Pressures were recorded using transducers in the acetabulum. We compared Charnley Ogee (flanged), Exeter contemporary (flanged) and Exeter low profile (unflanged) cups using Simplex and CMW1 cements in turn.Using Simplex, Charnley Ogee cup generated highest initial peak pressure and overall mean pressure. Exeter unflanged cup generated higher initial and mean pressures compared to Exeter flanged cup. With CMW, there was no significant difference between the pressures generated by the cups.Our experiment suggests that flanged cups do not consistently generate significantly higher cement pressures compared to unflanged cups.Aseptic loosening of the acetabular component is widely regarded as the commonest cause for revision surgery in THR [1-4]. Cement pressurisation has been shown to improve cup fixation in the acetabulum and in this regard, sustained pressurisation throughout the period of cement polymerisation has been shown to be more important than peak pressures [5,6]. Cement pressurisation prior to cup insertion is regarded as one of the most important factors in affecting the quality of cementation and thereby the survival of the cup. But once the cup is inserted, it would seem logical that allowing the cement to be contained inside rather than being extruded out would also improve cementation. In order to achieve this, flanged cups were introduced in 1976 [7], with a view to improve fixation. The idea was that a well fitting flange seated just inside the rim of the acetabulum would allow better containment of cement thereby generating higher cement pressures. However, the precise usefulness of a flange in practical situations has been repeatedly questioned.The debate between flange and unflanged cups in Total Hip Arthroplasty has been going on for quite some time now. A few studies have attempted to compare in vitro the pressures generated by flanged and
Influence of temperature on tightness of flanged joints under fatigue conditions  [cached]
TAC? Constantin,P?UNESCU Mihaela
Journal of Engineering Studies and Research , 2011,
Abstract: This paper presents the results of an experimental research on the properties of “It” gaskets, which are used to ensure the tightness of flanged joints at pressured vessels. In this work, were considered the vessels working at variable pressure and high temperature. Experimental data are used to determine a general relation for calculating the endurance reduction factor of the flanged joints. This factor is recommended for determining the safe life time of the gasket, which is the most sensitive constructive element of flanged joints.
Review of Bolted Connection Monitoring  [PDF]
Tao Wang,Gangbing Song,Shaopeng Liu,Yourong Li,Han Xiao
International Journal of Distributed Sensor Networks , 2013, DOI: 10.1155/2013/871213
Abstract: This paper reviews the research of monitoring technologies for bolted structural connections. The acoustoelastic effect based method, the piezoelectric active sensing method, and the piezoelectric impedance method are the three commonly used to monitor bolted connections. The basic principle and the applications of these three methods are discussed in detail in this paper. In addition, this paper presents a comparison of these methods and discusses their suitability for in situ or real-time bolt connection monitoring. 1. Introduction Bolts are important elements for detachable assembly of components in structures and machines. Bolts provide the required axial or preload forces on the components. A bolt’s axial load or preload has to be carefully controlled to ensure the safety and reliability of structures. Insufficient preload or excessive preload is a frequent cause of bolt joint failure [1, 2]. Monitoring the preload of high-tension bolts is critical in maintaining the strength and safety of bolted joints in engineering structures. There are many ways to indirectly measure bolt tension. Current practice relies on the torque wrench technique. However, with this technique, the torque load dissipates due to the friction between the bolt threads and the nut, which prevents accurate measurements of the axial load. The torque wrench method was reported to show large intrinsic errors in bolt tension measurement by up to 50%. This typically occurs since the torque applied to fastened bolts is consumed mostly by friction—only 10–15% of the torque is converted to the tension in the bolts. Friction consumes about 90% of the torque, with 50% dissipated in the bolt head and 35% in the bolt threads. Additionally, the friction varies so widely from bolt to bolt that errors of 50% are common, even with a perfect torque control. This complication leads to overconservative designs for safety, which in turn increases both weight and cost of bolted connections [3]. An effective way to measure the bolt strain is using a standard resistance strain gauge mounted to the body of the bolt. This method results in an accurate bolt-strain measurement. Another method, which is used when both sides of the bolt are accessible, involves a caliper to directly measure bolt elongation. However, in many instances, this is impossible since the bolt elongation is so small that it is difficult to measure it accurately. Please note that this method is not suitable for in situ monitoring. An ultrasonic method is considered as a valuable method to measure bolt axial load, which is based on
Analytic and Numerically Efficient Scattering Equations for an Infinitely Flanged Coaxial Line
Yong Heui Cho
PIER Letters , 2012, DOI: 10.2528/PIERL11110901
Abstract: An infinitely flanged coaxial line is analytically solved with the mode-matching technique and Green's function to propose a precise yet fast-convergent scattering solution for complex permittivity measurement. Based on virtual current cancelation, we formulate the open half-space fields in terms of coaxial modes and related Green's functions and thus obtain the simultaneous equations with rapidly convergent integrals. Numerical computations were performed in terms of reflection coefficients and radiation patterns.
Open End Correction for Flanged Circular Tube from the Diffusion Process  [PDF]
Naohisa Ogawa,Fumitoshi Kaneko
Physics , 2013, DOI: 10.1088/0143-0807/34/5/1159
Abstract: In the physics lessons on waves and resonance phenomena in high school and college, we usually consider sound waves in a tube with open or closed ends \cite{ResnikHalliday}. However, it is well known that we need a tube with open end correction $\Delta L$. The correction for a flanged circular tube was first given by Rayleigh \cite{Rayleigh} and experimentally checked by several authors \cite{exp}. In this paper, we show the different methods of obtaining the end correction for a circular tube by a diffusion process.
The Simple Model for Bolted Connections in Fire  [PDF]
Mahmoud Yahyai, Mohsen Behzadpoori, Amir Saedi Daryan, Ahmad Baleh Moghadas
Engineering (ENG) , 2011, DOI: 10.4236/eng.2011.39106
Abstract: Recent structural collapses caused by fire have focused attention on research concerning fire safety in building design. Steel connections are an important component of any structural steel building as they provide links between the principal structural members. Considering the importance of this matter this paper describes a spring-stiffness model developed to predict the behavior of bolted angle connections bare-steel joints at elevated temperature. The joint components are considered as springs with predefined mechanical properties i.e. stiffness and strength. The elevated temperature joint’s response can be predicted by assem-bling the stiffness of the components which are assumed to degrade with increasing temperature based on the recommendations presented in the design parameters code. Comparison of the results from the model with existing experimental data showed good agreement. The proposed model can be easily modified to describe the elevated temperature behavior of other types of joint as well as joints under large rotations.
Numerical and experimental investigation of bolted joints
JE Jam, NO Ghaziani
International Journal of Engineering, Science and Technology , 2011,
Abstract: In this study, the behavior and the damage caused in the bolt joints in sandwich structures with laminates made of glass fiber and foam core is investigated. Many investigators have studied the strength of mechanically bolted joints in composite structures but there is less in sandwich structures. It is performed on a fully composite airplane at the connection area of the wing to the fuselage and the landing gear. The area around the joint is surrounded by the laminates from glass layers (solid laminate) and its thickness is equal to whole thickness of sandwich panel. Different states of connection between the solid laminates, where the bolt connection is imbedded are studied. Also, the foam core around the connection is studied and the dependence of the magnitude of damage on various parameters like the connection angle, size, and the general shape of the solid laminate on buckling is evaluated. For considering the bolted joint performance, a three dimensional finite element model has been developed by ANSYS commercial code. Two proposed circular and squared shape of solid laminate has been considered. The results indicate that the squared shape as compared circular design will decrease the damage significantly. The best solid laminate interface angle (θ) which decreases the damage obtains 45o and solid laminate length is not effective in damage value. Eventually, the effect of these parameters on the local buckling due to the concentrated loading applied to the bolt connection in the sandwich structure is investigated. For confirming the analytical outcomes some experimental models were performed. For testing the analytical results a fixture has been designed. The results of the tests show that the results of the finite element analysis and those of the experimental results are closely related.
A Flanged Parallel-Plate Waveguide Probe for Microwave Imaging of Tumors
Huiyu Zhang;Soon Yim Tan;Hong Siang Tan
PIER , 2009, DOI: 10.2528/PIER09090901
Abstract: This paper presents a microwave imaging method for malignant tumors using flanged parallel-plate waveguide probes, based on detecting the significant difference in complex permittivity that exists between the tumor and its surrounding tissues. The presence of a tumor is identified from a frequency scan of the resonant scattering parameters. The tumor location can be estimated using S obtained at various positions of the region of concern, e.g. human organ, biological tissues, etc., while another probe transmits at the position yielding maximum resonating response of S, with triangulation technique. A tumor can also be distinguished from clutter items. With specific reference to the detection of breast cancer, simulation studies are presented to verify the performance of this probe and the proposed detection technique.
Study of Stiffness of Linear Guide Pairs by Experiment and FEA  [PDF]
Azhar Shaukharova, Yi Liang, Hutian Feng, Bin Xu
World Journal of Engineering and Technology (WJET) , 2016, DOI: 10.4236/wjet.2016.43D015
Abstract:
Linear guide pairs are the main part of the CNC machine tools. The dynamic behaviours are the main properties of the linear guide. These properties can mainly increase the service life of linear guide pairs. The main propose of this study is the comparison of stiffness of linear guide pairs by FEA and experiment. Measure the stiffness experimentally and, compare the results with FEA to prove the correctness of FEA model. For studying was chosen three linear guides: Chinese company-1, Chinese company-2 and abroad company. The results of this study are (1) Set up the finite element model of linear guides with different geometrical parameters. (2) Comparison of FEA and experiment results shows almost same results. (3) The FEA results show correctness of analysis. These studies are useful for establishing the stiffness on different structures of linear guides.
BOLTED TIMBER JOINTS WITH SELF-TAPPING SCREWS
Echavarría,César;
Revista EIA , 2007,
Abstract: the use of self-tapping screws with continuous threads in the joint area as a reinforcement to avoid splitting of timber members is studied. a theoretical model is developed to calculate the stress distribution around a pin-loaded hole in a timber joint, to predict brittle failure modes in bolted connections and to calculate the load in the reinforcing screws. laboratory experiments on reinforced and non-reinforced timber joints with 15,9-mm bolts have shown good agreement with the model predictions.
Page 1 /100
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.