Flange Design Research Articles

A Study on the Design of the Top Flange of a Modular T-Girder Bridge Using the Limit State Design Method

This study involved applying a design code change on a modular bridge design. The top flange of a modular T-girder bridge was examined by the Korean Highway Bridge Design Code Limit State Design (2015) and was compared with the Korean Highway Bridge Design Code (2010) in terms of the stability under the bending moment. In addition, the cross-sectional height and reinforcement amount were re-designed to obtain a safety factor similar to the original code. The reinforcement arrangement and development of the transverse joints were examined in the section considered. The result indicated that the application of the Korean Highway Bridge Design Code Limit State Design (2015) increased the bending moment safety factor and decreased the width of the transverse joints. The results of the re-design with respect to a safety factor similar to that in the Korean Highway Bridge Design Code (2010) indicated that it was possible to reduce the cross-sectional height and reinforcement amount. Furthermore, based on the obtained section, the results revealed that the width of the transverse joints could be reduced by changing the arrangement of lap splices from the straight bar to the loop.

Bolt Fatigue Strength for the Tower of Large-scale Horizontal Axis Wind Turbines

For achieve the anti-fatigue strength design of the tower flange’s bolts for the large-scale horizontal axis wind turbines, the checking method of fatigue strength was proposed based on the Schmidt-Neuper model. According to the stiffness distribution ratio of single sector flange system, the nonlinear relationship of internal force-external tension was established for the bolt. The sequential stresses of the bolts were derived through the linear interpolation of load, and the fatigue cumulative damage distribution of the whole bolt circle was obtained by using the rain flow counting and accumulated damage calculation. Furthermore the position of the maximum fatigue cumulative damage can be found. And on this basis, the effect of some parameters such as retightening force of bolts, number of bolts and thickness of flange to the maximum fatigue cumulative damage was analyzed. The results showed that the proposed method and procedure was feasible and effective in analyzing and checking the fatigue strength of the tower flange bolts.

A closer look at increasing HPGR efficiency through reductions in edge effect

Edge effect is a condition widely observed in High Pressure Grinding Roll (HPGR) operations that gives rise to reduced comminution at the edges of the roll surfaces. This effect is caused by a reduction in the local crushing pressure at the edges of the rolls resulting from the sliding friction between the static cheek plates and HPGR feed material. Practically, this has an impact on equipment sizing, as the edge effect leads to coarser particles reporting to downstream equipment in open-circuit operations and increased circulating load and diminished HPGR circuit capacity in closed-circuit operations. To address this, Metso’s HRC™ HPGR incorporates an Arch-frame to maintain a parallel relationship between the rolls and allow for the use of a flanged roll design. We conducted a series of pilot-plant tests with a 750 mm by 400 mm HRC HPGR to compare the performance of the flanged roll design against that of a traditional cheek plate arrangement under similar operating conditions. The edge effect was found to be significantly reduced with the flanged roll design. Based on the pilot-plant results, the implications for circuit design, energy efficiency and overall plant performance in a full-scale application were investigated and discussed.

Development of the design and manufacturing technology of bimetallic flanges of ship seawater pipelines

Development of the design and manufacturing technology of bimetallic flanges of ship seawater pipelines

Flanged Connections of Steel Tubular Sections under High Bending Stresses: A Comparison between Two Thickness Design Methods

This work presents a comparison of different possibilities of flange design of an aeolian tower structure, focusing the thickness determination, the critical connection parameter. The dimensioned structure is a fifteen-meter length tubular arm under bend stresses caused by wind loads and by gravitational loads, since the tubular arm might be horizontal or vertically positioned. The tubular sections connected by the flanges are all circular with external diameter varying from 270 to 360 mm and the flange modules are also circular shaped. Since the tubular diameters are relatively large, the lever effect plays a definitive role in the design. Most of the fluid conduits flange design criteria are not applicable for such diameters sizes and have a load case different from those of an aeolian tower. Two different approaches are presented and their flange thickness results compared.

Integrity analysis of an upper guide structure flange

Abstract The integrity assessment of reactor vessel internals should be conducted in the design process to secure the safety of nuclear power plants. Various loads such as self-weight, seismic load, flow-induced load, and preload are applied to the internals. Therefore, the American Society of Mechanical Engineers (ASME) Code, Section III, defines the stress limit for reactor vessel internals. The present study focused on structural response analyses of the upper guide structure upper flange. The distributions of the stress intensity in the flange body were analyzed under various design load cases during normal operation. The allowable stress intensities along the expected sections of stress concentration were derived from the results of the finite element analysis for evaluating the structural integrity of the flange design. Furthermore, seismic analyses of the upper flange were performed to identify dynamic behavior with respect to the seismic and impact input. The mode superposition and full transient methods were used to perform time–history analyses, and the displacement at the lower end of the flange was obtained. The effect of the damping ratio on the response of the flange was also evaluated, and the acceleration was obtained. The results of elastic and seismic analyses in this study will be used as basic information to judge whether a flange design meets the acceptance criteria.

Partially open crack model for leakage pressure analysis of bolted metal-to-metal flange

Predicting the leakage condition is of primary importance when designing metal-to-metal flanges. The gap between flange surfaces is regarded as a partially open crack with a zero stress intensity factor, then a model based on fracture mechanics is proposed for predicting leakage pressure. An analytical solution was found, with weight function, considering the condition of crack front at the most internal point of the bolt hole. Finite element and experimental tests validated the effectiveness of the model. In addition, the dependencies on the main flange dimensions were investigated and discussed, providing useful guidelines for optimal flange design.

Modified Waveguide Flange for Evaluation of Stratified Composites

Nondestructive evaluation of stratified (layered) composite structures at microwave and millimeter-wave frequencies is of great interest in many applications where simultaneous determination of the complex dielectric properties and thicknesses of multiple layers is desired. Open-ended rectangular waveguide probes, radiating into such structures, are effective tools for this purpose. The technique utilizes a full-wave electromagnetic model that accurately models the complex reflection coefficient as a function of frequency and material properties. While the electromagnetic model assumes an infinite waveguide flange (or ground plane), the measurements are conducted using a finite-sized flange. Consequently, the results of the electromagnetic model and those from measurements may not be sufficiently alike for accurate dielectric property and thickness evaluation. This paper investigates the effect of using an open-ended waveguide with a standard finite-sized flange on the error in evaluating the complex dielectric properties of a composite structure. Additionally, we present the design of a novel flange that markedly reduces this undesired effect by producing very similar electric field properties, at the flange aperture, to those created by an infinite flange. Finally, the efficacy of the design for evaluating the dielectric properties of a layered composite structure is demonstrated as well.

Robust Reliability Design of Banjo Flange Based on Bayesian Theory

The perturbation method, bayesian statistics theory, the reliability optimization design, the reliability sensitivity technique and robust design are employed to present a practical and effective approach for the robust reliability design of the Banjo flange under incomplete information. The theoretical formulae of robust reliability design for the Banjo flange under incomplete information are obtained. The respective program can be used to obtain the robust reliability design parameters of the Banjo flange under incomplete information accurately and quickly.

Metrological Traceability in Waveguide S-parameter Measurements at 1.0 THz Band

We have improved the measurement uncertainty for rectangular waveguide vector network analyzer (VNA) measurements in the WM-250 (WR 1.0), 750 GHz-1.1 THz frequency band. We developed a new waveguide flange design for precise connections and dimensional measurements to establish traceability to SI in VNA measurements. This is the first such achievement to be reported using a VNA in the terahertz frequency band.

Finite Element Analysis of Top Flanged Joint System of High Power Level Wind Turbine

This paper uses non-linear finite element method to structurally analyze top flanged joint system of a MW wind turbine, sets up a finite element model of top flanged joint system by applying finite element analysis software MSC.Marc/Mentat, makes an analysis on the stress distribution of key components of top flanged joint system under ultimate operating mode based on applying appropriate boundary condition and loads, and carries out security examination on top flange and joint bolt. Result shows that key components of the top flanged joint system can satisfy design requirements, and it has a guiding role for rational design and performance improvement of large scale wind turbine flange, which can be used in structural analysis of other flanged joint systems, and has certain practical value in the aspect of engineering.

Distal humerus cortical strains following total elbow arthroplasty

The aseptic loosening of total elbow replacements is a serious complication resulting in significant patient morbidity. It is thought to occur secondary to stress shielding of the distal humeral cortex by the stiff stem of the implant. Some total elbow prostheses incorporate an anterior flange intended to improve implant stability and peri-articular load transfer in an attempt to reduce this effect However, few studies have directly assessed the changes in cortical strains following total elbow arthroplasty or the biomechanical advantage of the anterior flange design. A regular and a long flange Coonrad-Morrey total elbow prosthesis were implanted into six Sawbone synthetic humeri. The constructs were subjected to physiological loads in axial compression (500 N), antero-posterior bending (50 N) and antero-posterior compression with condylar supports (300 N). Digital image correlation was used to measure the distal antero-lateral cortical strains and the results compared with those of whole Sawbones that had been tested in the same way. Significant stress shielding was demonstrated over the distal humeral cortex following prosthesis implantation during axial compression. In contrast, cortical strains increased following prosthesis implantation during antero-posterior compression with condylar supports. The increase in cortical strains following total elbow arthroplasty may help to maintain the integrity of the anterior cortex offering additional stability for implants with an anterior flange. These results are important for the development of future total elbow prosthesis designs and indicate that simulating the action of the forearm muscles is essential when evaluating changes in strain about the distal humerus in vitro.

Selection of initial gasket width

Correctly selected gasket width for forced-type detachable sealed joint is one of the conditions of leaktightness of the joint under the operating conditions at minimal material content of the joint itself. In this article, the calculation of the initial gasket width has been made more precise taking account of the real nature of radial deformation of the gasket upon axial loading. The calculating expression obtained has been used to determine the initial appropriate width of the gasket. Experiments have been carried out to study the conditions of radial deformation of the gasket. The experimental and calculated results are virtually congruent. The data reported in this article help disclose the real nature of gasket deformation in flanged joint, which allows one to remove errors from the calculating expressions used, determine the allowance for reducing the material content without impairing the leak-tightness of the flanged joint and the strength of its constituent elements, and select a more optimal flanged joint design. A requisite condition for normal performance of a detachable sealed joint is use of a gasket with an optimal width. A gasket in a forced-type joint is loaded for its assembly with a greater force than in the operating state. If the pressure of the sealing medium is raised, the gasket, upon unloading, must retain its resilient state. This condition can be assured only if the joint is assembled with a fixed compressive force, which creates a specific load q gk on the gasket. The load must not be higher than the limiting value, at which the gasket material retains its resilience under the operating conditions. Some sources [1] reported the values of the axial load q gk on the gasket, at which its material retains resilience. For instance, q gk of 3.5 and 5.0 MPa is recommended for soft and hard rubber, respectively, 25 MPa for fluoroplastic-4 (polytetrafluoroethylene, also known as Teflon), 100 MPa for AD-type aluminum, and 160 MPa for copper. Retention of the resilience of the gasket material and leak-tightness of the joint also depend on the gasket width. If the gasket width is more than the optimal, greater force will be required for preloading the fastening threaded elements, which will increase the material content of the joint and, consequently, its cost. If the gasket width is less, the leak-tightness may be lost under the operating conditions because of loss of resilience of the gasket material in the joint assembling process. Various recommendations are offered in the technical literature (without sufficient justification) for selecting the width of sealing gaskets. Only in [2] is given a fairly substantiated expression for determining the requisite width of the gasket:

The development of design guidelines for the application of formed-in-place gaskets

This technical feature discusses the dimensioning and design of formed-in-place gaskets – both anaerobic gaskets and silicone sealants. The differences between these two groups are highlighted using data from strength tests done to quantify the influence of different environmental factors. The effect of these factors, including temperature, layer thickness, superposition of assembly stress, and surface cleanliness and the material of the assembly parts, is also demonstrated. Finally, the resulting difference in flange design requirements for anaerobic gaskets and sealants is described.

Robust springback optimization of a dual phase steel seven-flange die assembly

This paper investigates robust springback optimization of a DP600 dual phase steel seven-flange die assembly composed of different flange designs. The optimum values of the die radius and the punch radius are sought to minimize the mean and the standard deviation of springback using surrogate based optimization. Springback values at the training points of surrogate models are evaluated using the finite element analysis code LS-DYNA. In this work, four different surrogate modeling types are considered: polynomial response surfaces (PRS) approximations, stepwise regression (SWR), radial basis functions (RBF) and Kriging (KR). Two sets of surrogate models are constructed in this study. The first set is constructed to relate the springback to the design variables as well as the random variables. It is found for the first set of surrogate models that KR provides more accurate springback predictions than PRS, SWR and RBF. The mean and the standard deviation of springback are calculated using Monte Carlo simulations, where the first set of surrogate models is utilized. The second set of surrogate models is generated to relate the mean and the standard deviation of springback to the design variables. It is found for the second set of surrogate models that PRS provides more accurate springback predictions than SWR, RBF and KR. It is also found that introducing beads increases the mean performance and the robustness. The robust optimization is performed and significant springback reductions are obtained for all flanges ranging between 7% and 85% compared to the nominal design. It is also found that a design change that decreases the mean springback also reduces the springback variation. It is observed that the optimization results heavily dependent on the bounds of the die and punch radii. In addition, optimization with multiple surrogates is investigated. Finding multiple candidates of optimum with multiple surrogates and selecting the one with the best actual performance is found to be a better strategy than optimizing using the most accurate surrogate model.

Deflections of A Multipass Shell-and-Tube Heat Exchanger Bolted Joint Subjected to Nonaxisymmetric Thermal Loading

Despite the fact that multipass shell-and-tube heat exchangers operating at high temperature are subject to frequent problems related to flange sealing, there is neither detailed explanations for the reasons of the failures nor an adequate solution to this problem. Specific geometry of multipass heat exchangers and the temperature difference between the inlet and the outlet fluids is responsible for the existence of a thermal circumferential gradient at the shell-to-channel bolted joint. However, existing flange design methods do not address nonaxisymmetrical temperature loading of the flanged joint assembly. The circumferential thermal gradient, as the cause of frequent failures to seal the flanged joints, is ignored. This paper outlines the analytical modeling of a flanged joint with a tube sheet of a multipass heat exchanger subjected to a nonaxisymmetrical thermal loading. A shell-and-tube heat exchanger of 51 in. diameter with cocurrent flow was used for analysis. The main steps of the theoretical analysis used for the determination of the circumferential temperature profiles and the thermal expansion displacements and distortions of the bolted joint components are given. The results from the proposed analytical model are compared with those obtained from finite element models.

Corneal Abrasions Associated With Crawford Mono-Canalicular Tubes

Corneal abrasions are a known complication of lacrimal intubation. The authors describe two consecutive patients in which this occurred using the JEDMED (St. Louis, MO) mono-canalicular tube, and propose a mechanism, based on the flange design, as an explanation.

A Model Dipole for FAIR SIS300: 3D Design of the Mechanical Structure

The FAIR facility, under development at GSI, includes the synchrotron SIS300 (300 Tm rigidity). In order to reach the required high intensities of proton and heavy ion beams, the bending dipole magnets have to be pulsed from the injection magnetic field of 1.5 T up to 4.5 T maximum field at the rate of 1 T/s. These 7.8 m long magnets have cos-theta shaped coils with a 100 mm bore with the particular characteristic to be geometrically curved (the sagitta is 114 mm). The 2D mechanical cross section has been designed in detail: it consists of 3 mm thick laminated stainless steel collars, assembled through keys, and 1 mm thick iron yoke laminations, assembled through large stainless steel C-shaped clamps. This paper analyses some aspects that are intrinsically 3-dimensional: the mechanical behavior of the ends, the effect of the longitudinal pre-stress, the design of the external flange and outer shell.

Measurement of Liquid Leakage and Comparison with Gas Leakage

The gasketed flange design is done referring to the only gas leakage test result, but it is not considered the liquid leakage because there is no handy method of measuring liquid leakage. In this study, a handy measuring method of the amount of a liquid leakage of gasketd flange is examined. Moreover, the comparison between the amount of a liquid leakage and the amount of the gas leakage is done. Here, it used water for liquid, helium gas for gas. In the result, the amount of water of the volume leakage was able to be measured handily. Moreover, when the result was converted into the mass leakage, it was clarified that it was equal to the amount of the helium gas leakage. Therefore, there is no problem that gasketed flange of the gas piping and liquid piping is designed for same method.

PVRC surveys flat face flange designs

PVRC surveys flat face flange designs