Metal Flange Research Articles

Next Generation High Powered RF and Optical Packages

RF signals are radio waves that are very crucial for telecommunications. Quality communications require reliable materials which are appropriately processed to house high-powered semiconductors such as GaN and GaAs. It is equally crucial to accommodate passive electronic components along with these semiconductors into the housings for the Next Generation RF package or GenPack™. Evolving semiconductor technologies demand fail-safe packages to protect the devices in all applications and environmental conditions. Future aircraft, EV cars, spacecraft, augmented and/ or virtual reality headsets, medical devices and many more technologies require operating at a higher power and frequency with a proper thermal and power management platform. The higher speeds of telecommunications hinge on the performance of semiconductors and their packages. Therefore, the GenPack™ and packaging process are becoming crucial pieces of the supply chain. Rugged GenPack™ RF packages differ in several ways compared to the traditional air cavity packages. For instance, FR-4 or Flame-Retardant glass-reinforced epoxy laminate material can be replaced with Aluminum Nitride or Alumina Oxide, Silicon Nitride or even Sapphire. The switch offers mechanical bonding directly onto the thermal spreader. Traditional circuits created on printed circuit boards have limited ability to dissipate heat due to the low thermal conductivity of FR4. Circuits created on ceramic can dissipate higher amounts of heat. As in the organic FR4 boards, multiple vias can be formed in the ceramic substrates to create metal pads top the ceramic that are grounded to the flange beneath the ceramic. A metal flange can be positioned beneath the ceramic to provide a heat spreader and electrical ground that can be bolted onto a heatsink. Flanges can be made from a diamond metal matrix composite instead of lower thermal conductivity materials to provide much more efficient thermal transfer. Furthermore, narrow leads offer optimized impedance at RF and microwave frequencies. A range of ceramic and flange materials can be selected to optimize GenPack™ RF Packages with cost, quality, and performance in considerations for the respective applications.

Investigation of resistance spot weld failure in tailor hot stamped assemblies

A novel experimental method, dubbed the “Mode I Caiman test”, is introduced to characterize spot weld failure and propagation within spot weld groups. The test configuration comprises a partially welded pair of channel sections subjected to Mode I tensile loading through an opening mode loading applied at the un-welded end of the channels. Experiments were performed considering hot stamped USIBOR® 1500-AS in a fully hardened condition (fully quenched) or in a tailored condition in which the strength of the welded flanged regions was altered using in-die heating (IDH). Both static and dynamic loading conditions are considered. The static loading utilized a conventional tensile frame while the dynamic experiments were performed on an instrumented crash sled at velocities of 7.5 m/s.A high speed thermal imaging camera was utilized to detect the temperature rise associated with plastic work during individual weld failure. This proved to be a rather novel and effective technique to detect weld failure and enabled tracking of weld failure propagation through the weld group for the different parent metal (flange) conditions.The experiments served to demonstrate the complex interaction between weld nugget, heat affected zone (HAZ) and parent metal strengths. For high parent metal strengths (fully quenched, martensitic condition), the welds exhibited interfacial and weld pull-out failure modes with rapid unzipping of the weld group resulting in relatively low energy absorption. In contrast, the lower strength tailored flanges exhibited a more stable (slower) failure propagation through the weld group and considerably higher energy absorption which is largely attributed to greater dissipation through deformation of the flange itself. Numerical simulations of the experiments were performed using spot weld models calibrated from single weld lap shear, cross tension, and coach peel experiments. The models captured the peak loads rather well, but predictions of rate of failure propagation within the weld line exceeded that seen in the experiments, pointing to the need for improved post-failure models for spot weld simulation.In automotive structures in which numerous welds are present, the amount of energy absorbed in weld failure can significantly affect the impact response of the structure. The Mode I Caiman test presents a new opportunity to calibrate the energy release rate of spot weld damage models to improve their accuracy when modelling spot welded connections involving multiple spot welds.

Stress Analysis of ASME Section X Flanges Using Classical Lamination Theory

AbstractThe increased usage of fiber reinforced plastic (FRP) composite pressure vessels and piping components in the past decades in the residential and industrial sectors is attributed to the FRP material resistance to corrosion and chemical attacks. FRP composite flanges are, however, known for their anisotropic behavior. In the ASME code section X, FRP composite flanges are treated using an analytical approach derived from that metallic flanges in addition to the fact that the geometries are made to fit them as much as possible and not designed independently. This is known to have caused structural flaws for certain FRP flange classes and sizes. Using a recently developed anisotropic FRP flange approach, it is proposed to identify the most critical flanges by analyzing the flange parameters such as flange ring rotation and stresses in their different parts; gasket, flange ring, hub, and shell subjected to pressure loading. The study on the strength of flanges described in ASME section X RD-620.1 table, will reveal the most critical size and class flanges and their highly stressed locations. To conduct such a study, the selected flange material is an E glass/Vinyl Ester laminate composite. The study shows that FRP flanges of classes 25 and 50 are most vulnerable and should comparatively be less loaded. The stresses are found to reach 50 MPa in the shell and 58 MPa in the flange ring while the maximum flange rotation is 0.83 deg.

Tube Joining by a Sheet Flange Connection

Joining of tubes to tubes by means of plastic deformation at ambient temperature allows one to solve the main limitations produced by the necessity of joining thin-walled tubes of low-to-medium diameter size made from materials that are not suitable to be welded and/or have reduced contact interfaces. The new joining solution allows one to obtain permanent mechanical joints of tubes or pipes by means of an accessory lightweight sheet metal flange subjected to annular indentation and subsequent injection of its material towards the tube walls to produce a mechanical interlock between the different elements. The sheet-flange connection can then be utilized to affix the joined tube assembly to walls or other different structures and equipment, by means of fasteners or other joining accessories attached to the sheet flange. Similar or dissimilar material combinations can be easily and safely produced while guaranteeing levels of leak-tightness within the maximum internal operating pressure of the individual tubes. A combined numerical–experimental approach is employed to identify the operative parameters as well as to explain the deformation conditions. Pull-out loads and internal fluid pressure are applied to the manufactured joint to evaluate its behavior under typical operating conditions that it may be subjected to during its service life depending on the application.

Structural design optimization of composite materials drive shafts

Composite materials drive shafts attract particular interest in recent years. Their high strength, light weight and high fatigue and corrosion resistance make them suitable for high specification mechanical and marine applications. In the context of the present work, advanced finite element models that simulate the static and dynamic mechanical behaviour of composite drive shafts are combined with optimization algorithms in order to determine the optimum lay-up of a composite shaft according to the desired specifications. The composite shaft is also combined with metallic flanges and the performance of the combined system is also investigated. The created models facilitate the structural design optimization of composite material drive shafts and constitute the basis for the future implementation of the simulation driven digital twins of composite materials drivetrain systems.

Composite and Metal Structural Elements Joint Strength

The paper reveals the hybrid structure strength studies results, which consists of composite and metal parts. The object of the study was an experimental transmission shaft of an aircraft high-lift system. It consisted of a composite tube and metal flanges. New high-strength composites, modern metal powders and additive technology were used for its manufacture. This is the feature that differ the shaft from the typical metal structures used at present. The shaft strength investigation included static tests and calculations. During the tests, the maximum torque and the corresponding shaft twist angle were determined. Based on the computational analysis results, the critical stresses and reserve factors of its structural elements were calculated. The assessment of the effectiveness of the new technologies application for joining structural elements using discrete pins was carried out.

Effect of reinforced fibers on the vibration characteristics of fibers reinforced composite shaft tubes with metal flanges

The fiber-reinforced composite (FRP) shaft need to consider vibration performance of the transmission system to improve work efficiency, comfort, service life and safety. The fiber materials and tubes containing metal connectors are important parts of the FRP shaft so that the study on the vibration performance of these two key components is of great significance for an in-depth understanding of the vibration performance of shafts. The finite element analysis (FEA), pulse vibration excitation technique (PVET) and formula computing were used to study the effect of the vibration characteristics of shafts. This study revealed that increasing the modulus of the fiber is one of the effective methods to increase the natural frequency of the FRP tube and the damping ratio of the carbon FRP tubes were slightly smaller compared with basalt and glass fiber. The FEA of FRP tube results were not distinct from the measured and calculated results so that these FEA results were relatively reliable. The damping of the tube with metal flanges at both ends were weaken compared the FRP tube. This work will be of great significance to the optimization design of the vibration performance of FRP shafts.

On the Modeling of Anisotropic Fiber-Reinforced Polymer Flange Joints

Abstract Fiber-reinforced plastic composite flanges have recently experienced a spectacular development in the area of pressure vessels and piping. The current procedures used for the design of these flanges are a major concern because of their inappropriateness to address the anisotropic behavior of composite materials. The current ASME code section X related to the design procedure of composite flanges uses the same analytical method as that of section VIII division 2, which treats the flanges as isotropic materials such as metallic flanges. This study deals with Fiber-reinforced plastic (FRP) bolted flange joints integrity and bolt tightness. A new developed analytical FRP model that treats anisotropic flanges with and without a hub is presented. The model is based on the anisotropy and a flexibility analysis of all joint elements including the gasket, bolts, and flanges. It is supported experimentally with tests conducted on a real NPS 3 class 150 WN FRP bolted flange. Furthermore, three different numerical models based on three-dimensional anisotropic layered shell and solid element models were conducted to further compare and verify the results obtained from the new developed analytical approach. The results show that the new model has potential to be used as an alternative tool to FEM to analyze the stresses and deformation of problematic FRP bolted joints.

EFFECT OF ALUMINUM FOILS NUMBER AND ITS LENGTH IN IMPROVEMENT OF ELECTRIC FIELD DISTRIBUTION OF HIGH VOLTAGE CONDENSER BUSHING

High voltage condenser bushing is one of the important component that is widely used in the high voltage system. At high voltage levels more than 52kV the distribution of electric field in condenser bushing is irregular between the lead conductor and the grounded metallic flange. This paper studied the effects of changing in both: the number layers of aluminum foils and Oil Impregnated Paper (OIP), increasing the length of aluminum foils layers, and also increasing the thickness of OIP layer on the distribution of electric potential and electric field in condenser bushing by using Finite Element Method (FEM) and built the bushing model in ANSYS software. The harmonic analysis was performed of the bushing model at maximum value of withstand voltage test at 50Hz, from the analysis results are obtained the maximum value of electric field on the inner and outer surface of the bushing, the obtained electric field values were good and acceptable compared to the permissible electrical stress values of the dielectric insulators. This work can also aid in the design of high voltage bushing stress control, a knowledge of the electrical field distribution in bushing geometry. Moreover, the results of analysis are shown as contour plots, graphs plotted, and tables.

Sapphire optical viewport for high pressure and temperature applications.

We describe the design of a soldered sapphire optical viewport, which is useful for spectroscopic applications of samples at high temperatures and high pressures. The sapphire window is bonded via active soldering to a metal flange with a structure of two c-shaped rings made of different metallic materials in between, so as to mitigate thermally induced stress. A spectroscopic cell equipped with two of the optical viewports has been successfully operated with alkali metals in a noble gas environment at temperatures in the range of 20-450 °C at noble gas pressures from 10-6 mbar to 330 bars. In the upper pressure range, we observe a leakage rate smaller than our readout accuracy of 30 mbar per day.

A numerical investigation of the sealing performance and the strength of a raised face metallic bolted flange joint

The development of leakage and strength of a metallic bolted flange joint are investigated in this work. Finite element analyses in 2D and 3D have been developed using ANSYS to study a steel flange and bolt with an aluminium gasket. The pressure-penetration criterion (PPNC) in ANSYS has been used to model fluid leakage propagation between the flange and the gasket. Validation was performed with a benchmark test, using published study of a bolted metallic flange joint; the agreement between the results is excellent. Results showed that the finite element method using PPNC is a good method to study leakage behaviour compared to other methods, which are relatively time-consuming and expensive. The influence of the flange dimensions on the maximum stresses and leakage propagation has been investigated in this study. Furthermore, the agreement between the 3D and axisymmetric 2D FEA models is very good, so the latter can be used to save computational time. This study was undertaken as a preliminary to a larger project about bolted flange joints made of composite materials.

Analytical modeling of FRP hubbed flanges

In spite of the increasing use of FRP composites in bolted flange joints and the good knowledge of these structures and their material behavior the procedure used for their design is that of metallic flanges. There is a major concern to appropriately address the anisotropic behavior of composite materials in FRP flange design. Therefore, it is necessary to revisit this procedure by implementing a more suitable model to analyse the stresses and strains of FRP bolted flange joints.This paper presents an analytical model that treats FRP bolted flange joints integrity and tightness based on anisotropy and a flexibility analysis of all joint elements including the gasket, bolts and flanges. The theories that treats all parts of the flange are described in details. Finally, the developed analytical model is validated with experimental testing and numerical modeling of different size FRP flanges.

Structure of RF fields in a twin-chamber radio-frequency inductive plasma source placed in a weak external magnetic field

An experimental study of the structure of waves excited in the low-pressure inductive radio-frequency discharge located in the magnetic field with inductance less than 70 Gs was carried out. A plasma source consisting of gas-discharge and process chambers was used in the work. The results of the wave structure study showed that a partially traveling wave was excited in the plasma source when a certain threshold value of the induction of an external magnetic field was exceeded and when a metal flange separating the gas discharge and processing chambers was used. It was also noted that the above-mentioned threshold value decreased with an increase in operating frequency. The amplitude and phase profile of the Bz component of the RF wave indicates the presence of waves reflected from the bottom flange and the local minimum of the electron concentration within the junction of the gas-discharge and process chambers.

An Enhanced One-Port Waveguide Method for Sheet Resistance Extraction

In this article, a simple and accurate method is proposed to extract the sheet resistance of a thin conductive film by using the enhanced one-port waveguide in a microwave frequency. A shorted quarter-wavelength waveguide is supplemented to the main waveguide as its open boundary to ensure the TE10 mode during the measurement. Unlike the available waveguide with the metal flange, the dielectric flange of the shorted quarter-wavelength waveguide is proposed to eliminate the transverse electromagnatic (TEM) wave propagation and leakage in the gap between two waveguide flanges. The conductive film deposited on the substrate is attached to the main waveguide flange, and the equivalent circuit model is generated thereof. By measuring S 11 parameters of the bare substrate and conductive film with the substrate, respectively, the unknown sheet resistance of the conductive film can be easily extracted. Even a large sheet resistance could be measured accurately. Both numerical and measurement results are presented for effectiveness validation of the proposed method. In comparison with the available dual-port method and waveguide with the metal flange method, the dielectric flange raises the measurement accuracy sharply in aspects of substrate thickness, substrate materials, and sheet resistance.

Vibration characteristics of carbon-fiber reinforced composite drive shafts fabricated using filament winding technology

The metal connector and tube of the composite drive shaft were bonded together generally. However, the glued shafts showed numerous risks due to the instability of chemical glues. To avoid potential risks, filament winding with integrated flanges was proposed to prepare carbon fiber-reinforced composite (CFRP) drive shafts in this study. The natural frequency and damping of CFRP shafts were investigated by FEA and experiment. Results revealed that the natural frequency of CFRP shafts embedded in metal flanges is slightly lower than that of the glued CFRP shafts. The metal flanges did not affect the changing trend of the natural frequency with various fiber ply angles or thicknesses, and the damping had little effect on the natural frequency. The natural frequency of CFRP tubes and drive shafts was predicted using FEA and agreed well with the experimental results. The results of this study will be of great significance in the design and application of CFRP drive shafts.

Plasma parameters in a twin-chamber RF inductive plasma source, placed in a weak external magnetic field

Experimental study of the plasma parameters in an RF inductive plasma source consisting of gas-discharge chamber and process chamber (GDC and PC) located in the magnetic field with inductance less than 70 Gs was carried out. The magnetic field was close to uniform in the PC and divergent in the GDC. The metal or dielectric flange was used as a separating element between GDC and PC. Experiments showed that an increase in the magnetic field at the pressures when the electron mean free path exceeds the longitudinal size of the plasma source and utilization of the operating frequencies of more than 2 MHz led to the formation of radially limited plasma column, which ended at the bottom grounded flange of PC. In this case, the plasma density in the PC became higher than in the GDC. In the area of the metal separation flange, there was a local minimum of the electron density as well as plasma potential, associated with the parasitic capacitive coupling between the antenna and the separating flange. The growth of the magnetic field led to the equalization of the axial potential distribution.At the operating frequency of 2 MHz, at the pressures at which the electron mean free path is less than the longitudinal size of the plasma source, the electron density as well as the space potential reaches a maximum in the GDC and, as a rule, decreases monotonously toward the PC.

Research on the Optimization Design of Metallic Gasket Based on DOE Methodology

In the present study, the method of simulation and Statistical Design of Experiment (DoE) combined approach has been applied to investigating the influence of metallic gasket, flange and bolt on sealing performance. In order to analyze the influence of wavy shape, bolt distribution, wavy height, gasket thickness, top flange thickness, top flange material, gasket materials and bottom flange material, the contribution degree of each factor to the bolt axial force and pressure distribution was taken as the evaluation index. Research results show that the corrugated shape and bolt distribution have the greatest influence on the pressure distribution of gasket and the range of the bolt axial force.

Seismic evaluation and analysis of 1100-kVUHV porcelain transformer bushings

Shaking table tests were carried out on five 1100-kV ultra-high voltage (UHV) porcelain transformer bushings to evaluate their seismic performance. Finite-element models of the bushings were established. The influence of different types of connection on the seismic responses of the oil-side bushings was analysed. A simplified method to rapidly estimate the seismic responses of transformer bushings was implemented. Test results indicated that the safety factors of the porcelain insulators met the seismic requirements of the relevant standards. However, the metal flange might have cracked in earthquakes. Increasing the rotational stiffness of the connection reduced the seismic responses of the oil-side bushings. The mode mass participating coefficients of the first mode of the UHV transformer bushings were between 0.6 and 0.65. The simplified method presented in this paper was able to estimate the seismic responses of the 1100-kV UHV transformer bushings, with results close to those of the shaking table tests.

Influence of Flange on Seismic Performance of 1,100-kV Ultra-High Voltage Transformer Bushing

Failures of the metal flange were observed in transformer bushings in previous earthquakes. In order to evaluate the influence of the flange on the seismic responses of 1,100-kV ultra-high voltage (UHV) bushing, two types of flanges were selected, which used different materials and layouts. The finite element (FE) and theoretical analyses were first carried out. The results indicate that there is an out-of-plane rocking effect at the flange bottom plate, and the flange will be damaged if the stiffeners are improperly designed. Then two identical bushings using different flanges were tested on the shaking table. The bottom plate of the cast aluminum flange cracked along the stiffeners accompanied by oil leakage. However, the UHV bushing with stainless steel flange survived in the test. It is concluded that the properly designed flange could improve seismic performance of UHV transformer bushings.

Design aspects regarding a hydraulic dissipation system assembly model and virtual operation results

Ensuring an optimal stability degree for building structures represents the basic engineers concern when working on developing projects for new structures or rehabilitation of old ones. The most important dynamic actions with destructive effects threatening a building structure are the seismic actions which place important stress under dynamic regime inside building structural elements but also vibration actions resulting from road or rail traffic acting on the bridge structure types. Special isolation methods have been developed, over time, in order to counteract the destructive effects of the mentioned dynamic actions by using mechanical devices directly mounted on the structural frames of a building, with the declared role of protecting the structure during the occurrence of these unexpected events. A structure having in composition such protective systems is considered an isolated structure against dynamic actions and devices used are classified as insulation systems or energy dissipative systems because they are able to consume an amount from the disturbing action input energy transforming it into another form energy, namely heat. A mechanical device model with energy dissipation properties is described in this paper that can be used for mounting at buildings and bridges in order to achieve energy consumption when a dynamic mode action acts on the isolated structure. This dissipative device assembly is achieved as a hydraulic cylinder with piston operating on the basis of a fluid with special viscosity properties. The piston, being solidary with the rod, has a number of orifices made necessary for the working fluid circulation so that when a request occurs it can perform a relative translational motion relative to the cylinder. The mounting solutions for the hydraulic dissipation system at the insulated structure are made by means of metal flanges positioned on the structural elements that allow a relative displacement during earthquakes and which must be limited by means of the energy dissipation action. An assembly model for the hydraulic dissipative device is built for which fluid flow analysis is performed inside the cylinder and through the piston orifices for different velocity values during rod translational motion. It is also analyzed the dissipation device operation for different orifice diameter values which ensure the working fluid circulation, as well as the different types of hydraulic fluid used. The results are presented for each case analyzed in part, where the role of dissipative device of the analyzed system is being emphasized.