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1 – 10 of over 3000
Article
Publication date: 1 March 1995

S.K. Chiang, D.F. DiFranco and D.G. Pucci

A new high strength, low profile copper foil (AM) has been developed by the authors' company. This foil is designated AM foil, which refers to its advanced metallurgy. The unique…

Abstract

A new high strength, low profile copper foil (AM) has been developed by the authors' company. This foil is designated AM foil, which refers to its advanced metallurgy. The unique attributes of this foil arise from its unconventional processing approach and the resulting microstructure. An extremely small and uniform grain structure enhances the metallurgy and decreases the foil profile. Random crystal orientation and high nucleation density eliminate porosity for all foils of various thickness. Other benefits related to this high strength and low profile foil include good handleability, outstanding etching performance, better control of dielectric thickness, very high elongation to reduce innerlayer cracks, improved oxide adhesion, as well as other advantages.

Details

Circuit World, vol. 21 no. 3
Type: Research Article
ISSN: 0305-6120

Article
Publication date: 4 August 2021

Hao Li, Haipeng Geng and Hao Lin

The misalignment is generally inevitable in the process of machining and assembly of rotor systems with gas foil bearings, but the exploration on this phenomenon is relatively…

Abstract

Purpose

The misalignment is generally inevitable in the process of machining and assembly of rotor systems with gas foil bearings, but the exploration on this phenomenon is relatively less. Therefore, the purpose of this paper is to carry out the thermo-elastohydrodynamic analysis of the foil bearing with misalignment, especially the inhomogeneous foil bearing.

Design/methodology/approach

The rotor is allowed to misalign in two non-rotating directions. Then the static and dynamic performance of the inhomogeneous foil bearing is studied. The thermal-elastohydrodynamic analysis is realized by combining the Reynolds equation, foil deformation equation and energy equation. The small perturbation method is used to calculate the dynamic coefficients, then the critical whirl ratio is obtained.

Findings

The gas pressure, film thickness and temperature distribution distort when the misalignment appears. The rotor misalignment can improve the loading capacity but rise the gas temperature at the same time. Furthermore, the rotor misalignment can affect the critical whirl ratio which demonstrates that it is necessary to analyze the misalignment before the rotordynamic design.

Originality/value

The value of this paper is the exploration of the thermo-elastohydrodynamic performance of the inhomogeneous foil bearing with misalignment, the analysis procedure and the corresponding results are valuable for the design of turbo system with gas foil bearings.

Details

Industrial Lubrication and Tribology, vol. 73 no. 6
Type: Research Article
ISSN: 0036-8792

Keywords

Article
Publication date: 14 January 2022

Fangcheng Xu, Zeda Dong, Jianhua Chu, Haoming Wang and Yongliang Wang

Gas thrust foil bearings (GTFBs) are used to balance the axial load of engines. However, in some working conditions of large axial force, such as the use of single impeller air…

Abstract

Purpose

Gas thrust foil bearings (GTFBs) are used to balance the axial load of engines. However, in some working conditions of large axial force, such as the use of single impeller air compressor, the load capacity of GTFBs is still insufficient. To solve this problem, the load capacity can be improved by increasing the stiffness of bump foil. The purpose of this paper is to explore a scheme to effectively improve the performance of thrust foil bearings. In the paper, the stiffness of bump foil is improved by increasing the thickness of bump foil and using double-layer bump foil.

Design/methodology/approach

The foil deformation of GTFBs supported by three different types of bump foils, the relationship between friction power consumption and external force and the difference of limited load capacity were measured by experimental method.

Findings

The variation of the foil deformation, bearing stiffness, friction power consumption with the external force at different speeds and limited load capacity are obtained. Based on experimental results, the selection scheme of bump foil thickness is obtained.

Originality/value

This paper provides a feasible method for the performance optimization of GTFBs.

Details

Industrial Lubrication and Tribology, vol. 74 no. 1
Type: Research Article
ISSN: 0036-8792

Keywords

Article
Publication date: 19 January 2010

M. Kulakov and H.J. Rack

The purpose of this paper is to examine the formation of surface damage associated with the ultrasonic consolidation (UC) of single ply 150 μm thick 3003‐H18 foil to a 3003‐18…

Abstract

Purpose

The purpose of this paper is to examine the formation of surface damage associated with the ultrasonic consolidation (UC) of single ply 150 μm thick 3003‐H18 foil to a 3003‐18 build plate and the relationship between the development of this damage state with the linear weld density (LWD) achieved during consolidation.

Design/methodology/approach

The influence of the consolidation control variables on the area fraction of the sonotrode induced top foil surface damage is established through application of a full factorial three‐level design‐of‐experiment methodology, the control variables limits being fixed by the capability of the UC system.

Findings

Detailed analysis of the foil top surface structure after consolidation reveals the presence of two characteristic, damaged and undamaged, regions. The former corresponded to plastically deformed areas, these being formed as a result of interaction of the foil top surface with the sonotrode, while the latter corresponded to the original foil surface. Sonotrode normal load, vibrational amplitude and its rotational velocity are found to have an interdependent affect on the development of the sonotrode‐induced top surface damage. Top surface damage initiates upon impression of the sonotrode into the foil surface followed by the commencement of oscillatory and forward rotational motion of the sonotrode. Finally, evidence is presented that the degree of sonotrode induced top surface damage bears a direct relationship with the linear ultrasonic weld density developed at the foil‐build plate interface, increasing top surface damage being associated with increased LWD.

Originality/value

A linear relationship between the degree of bonding at the foil‐build plate interface and the plastically deformed area on the foil top surface is established, this correlation demonstrating that bond formation between foils during UC depends on effective frictional conditions at the sonotrode‐foil interface.

Details

Rapid Prototyping Journal, vol. 16 no. 1
Type: Research Article
ISSN: 1355-2546

Keywords

Article
Publication date: 1 September 2006

Rudolf Wiechmann

Peel strength numbers are part of a laminate's specifications and should characterize the specific bond performance (copper adhesion) under test conditions. Unfortunately, from…

4421

Abstract

Purpose

Peel strength numbers are part of a laminate's specifications and should characterize the specific bond performance (copper adhesion) under test conditions. Unfortunately, from both a theoretical and a practical point of view they are not able to do that. This study seeks to address this issue.

Design/methodology/approach

This paper has been written to show the main impacts on the measured peel strength numbers in the IPC‐TM‐650 peeling test. From an extensive database regarding peel numbers for diverse foil types, foil thicknesses and treatment roughnesses it is possible to show the influence of prepreg type, foil thickness and roughness on the measure peel strength.

Findings

Copper adhesion to laminating resin is insufficiently described by peel strength data because of the impacts of foil thickness, stiffness on bending (physical bending work, stress distribution underneath the peeling line) and the treatment roughness. The latter works reinforcing regarding the (low) resin strength and this influence is measured on resin strength instead of real bond. Fracture due to peeling is cohesive, mostly with a totally intact copper‐resin interface. This is especially true in high performance laminates that show low peel strengths not because of bad copper bonding but because of brittle resins (filled and unfilled).

Originality/value

Users have to understand the limited benefit of the IPC peel test in characterizing copper‐resin bonds. Peel increase on (low bond) high performance resins by increased foil roughness is not a practical way in the field because of no bond improvement (interface) and heavy disadvantages in dielectric thickness (HiPot tests at thin core laminates), respectively.

Details

Circuit World, vol. 32 no. 3
Type: Research Article
ISSN: 0305-6120

Keywords

Article
Publication date: 1 March 1989

R. Klemencic, E. Kny and W. Schmidt

The thermal management of printed circuit boards with high component density is increasingly becoming an important factor in the efficiency and reliability of electronic systems…

Abstract

The thermal management of printed circuit boards with high component density is increasingly becoming an important factor in the efficiency and reliability of electronic systems. A well‐proven technique, which has been used to produce multilayer circuit boards in quantity for several years, is to incorporate metal foils. The metal foils significantly improve heat removal and impart to the circuit board a thermal expansion behaviour closely matching that of the ceramic chip carrier. Roll‐clad Copper‐Invar‐copper (CIC) and copper‐molybdenum‐copper (CMC) foils have been used for this purpose. This paper reports on the first use of Mo30Cu foils, a material produced by powder metallurgy consisting of 70% molybdenum and 30% copper. Contraves AG manufacture SMT multilayer circuit boards incorporating Mo30Cu foils produced by Metallwerk Plansee GmbH. With regard to machinability and physical characteristics, Mo30Cu foils are superior to roll‐clad foils. First of all, the high elastic modulus of Mo30Cu foils is worth mentioning. It positively influences thermal stability and mechanical stiffness of the circuit board.

Details

Circuit World, vol. 15 no. 4
Type: Research Article
ISSN: 0305-6120

Article
Publication date: 28 May 2020

András Jakab, Viktor Hlavicka, Ágoston Restás and Eva Lubloy

During the building designing, it is very important to deal with the fire resistance of the structures. The designed materials for escape routes should be selected to ensure the…

Abstract

Purpose

During the building designing, it is very important to deal with the fire resistance of the structures. The designed materials for escape routes should be selected to ensure the usability of the structures until the time of escape. Planning affects the glass structures similarly, so these can also be partition walls and load bearing structures, although the latter is less applied on escape routes. The heat protection of the glasses can be improved with heat-protective foils, while fire protection is provided by gel intumescent material.

Design/methodology/approach

To research the topic of fire resistance, laboratory experiments were carried out on small-scaled glass elements with thermal protection foil at Budapest University of Technology and Economics at the Department of Construction Materials and Technologies.

Findings

Fire protection of small model specimens was tested with blowtorch fire and furnace heat load. During the experiments, six foils were tested. Single pane glass, double layered and triple glazed specimens were tested with blowtorch fire.

Originality/value

Fire protection of small model specimens was tested with blowtorch fire and furnace heat load. During the experiments, six foils were tested. Single pane glass, double layered and triple glazed specimens were tested with blowtorch fire. In case of heat-protected glazing, the foils on the “protected” side of the single pane glass do not have a fire protection effect based on blowtorch fire test. For double glassed specimens, the P35 foil has a perceptible effect, even for the requirements of the flame breakthrough (E, integrity), when the foil is placed on the inner side (position 3) of the second glass layer. The stratification of each triple glazed specimens was effective against blowtorch fire load (3 M, S4&P35), so (EI, integrity and isolation) it can meet the requirements of flame breakthrough and thermal insulation.

Details

Journal of Structural Fire Engineering, vol. 11 no. 3
Type: Research Article
ISSN: 2040-2317

Keywords

Article
Publication date: 1 March 1999

Harish D. Merchant, Melvin G. Minor, Sid J. Clouser and Dan T. Leonard

The strain‐based flex fatigue of 18 μm thick copper foil is evaluated over a wide range of strain amplitudes. Seven electrodeposited foils, four commercial grades and three…

Abstract

The strain‐based flex fatigue of 18 μm thick copper foil is evaluated over a wide range of strain amplitudes. Seven electrodeposited foils, four commercial grades and three experimental foils, and a commercial grade rolled foil are characterized. The fatigue life versus cyclic strain amplitude curve in the high strain amplitude (low cycle) and low strain amplitude (high cycle) regimes is developed for each foil. On the basis of fatigue life (Nf) and fatigue ductility (Df), the low cycle fatigue performance of eight foils is ranked. Universal correlations of Nf and Df with the uniaxial tensile strength are established. Two electrodeposited foils, experimental foil DF 8 in the high strain amplitude regime and commercial foil DF 9 in the low strain amplitude regime, have been shown to display fatigue performance comparable to that of the commercial rolled GR 8 foil.

Details

Circuit World, vol. 25 no. 1
Type: Research Article
ISSN: 0305-6120

Keywords

Article
Publication date: 16 August 2019

Hongyang Hu and Ming Feng

The purpose of this paper is to investigate the effect of different wedge shapes on the performance of air foil thrust bearing (AFTB).

209

Abstract

Purpose

The purpose of this paper is to investigate the effect of different wedge shapes on the performance of air foil thrust bearing (AFTB).

Design/methodology/approach

During the study, a bump foil stiffness model considering slip deformation and a two-dimensional sheet top foil model is established, and the Reynolds equation and film thickness equation is solved using the finite difference method and finite element method. The static performance such as load carrying capacity, friction torque and power loss of AFTB under different taper parameters is obtained. The influence of different pitch ratio, film thickness ratio and wedge shapes on the bearing characteristics is studied.

Findings

There is an optimal height and a pitch ratio for the taper of AFTB with certain tile number. Compared to the plane and concave wedge shape, the upper convex shape can enhance the convergence effect of the wedge region, increase the effective film pressure distribution area of the bearing and reduce the local concentrated load of the top foil, which is more conductive to the increase of load capacity.

Originality/value

The wedge shape parameters bring a fundamental difference in the static performance of AFTB. The results are expected to be helpful to bearing designers, researchers and academicians concerned.

Details

Industrial Lubrication and Tribology, vol. 73 no. 1
Type: Research Article
ISSN: 0036-8792

Keywords

Article
Publication date: 8 June 2015

Kai Feng and Xueyuan Zhao

The purpose of this paper is to investigate the effects of misalignment on the static and dynamics characteristics of bump-type foil bearings (BFBs). High-speed and…

Abstract

Purpose

The purpose of this paper is to investigate the effects of misalignment on the static and dynamics characteristics of bump-type foil bearings (BFBs). High-speed and high-temperature oil-free turbomachinery can be realized with the use of gas foil bearings (GFBs). GFBs have a flexible supporting structure; thus, they can tolerate a higher degree of misalignment compared with rolling element bearings.

Design/methodology/approach

A test rig for GFBs has been developed to measure the effects of misalignment on the structure characteristics of bump-type foil bearings. The link-spring model, which is the foil structure model presented previously by the authors, is used as a basis in the present study to predict the static and dynamic performances of the foil structure. In general, predictions of the dynamic characteristics exhibit good agreement with the measurements acquired from the dynamic load tests.

Findings

Results from the static tests show that GFBs develop high stiffness when the misalignment angle increases. Moreover, the dynamic characteristics of GFBs are identified by considering the test bearing supported by a non-rotating shaft as a one-degree-of-freedom system. The results indicate that the dynamic characteristics of GFBs strongly depend on excitation frequency and excitation amplitude because of the variation in the dynamic friction force within the foil structure. The structural stiffness and equivalent viscous damping increase with an increase in the misalignment angle.

Originality/value

The present study focuses on the misalignment of GFBs and investigates experimentally the effects of misalignment on the structure characteristics of GFBs.

Details

Industrial Lubrication and Tribology, vol. 67 no. 4
Type: Research Article
ISSN: 0036-8792

Keywords

1 – 10 of over 3000