The Experts below are selected from a list of 177 Experts worldwide ranked by ideXlab platform

M F Fleszar - One of the best experts on this subject based on the ideXlab platform.

  • thermal behaviour of teflon phenolic liners in Self Lubricating Bearings
    Journal of Thermal Analysis and Calorimetry, 1997
    Co-Authors: M F Fleszar
    Abstract:

    Abstract  The gun system of the M1 series tank rides on a pair of Self-aligning spherical Bearings that allows the elevation and depression of the cannon. Because these Bearings are encapsulated within the rotor housing, periodic lubrication or maintenance is impossible. To overcome this problem Self-Lubricating Bearings were incorporated into the system. There are two basic liner designs, molded and fabric. Molded liners are produced by applying a formulation of teflon and typically asbestos into a phenolic resin, which is applied to the bearing surface, then cured. Fabric liners utilize a woven fabric bonded to the bearing surface, then teflon which is mixed into phenolic resin is applied to the bearing surface and cured. Initial studies of the existing bearing liner were completed to determine the liner composition and establish a baseline or standard to compare thermal and mechanical properties with potential vendors. DSC revealed an average teflon content of 39.53%, which varied significantly through...

  • Thermal behaviour of teflon/phenolic liners in Self-Lubricating Bearings
    Journal of Thermal Analysis and Calorimetry, 1997
    Co-Authors: M F Fleszar
    Abstract:

    Abstract  The gun system of the M1 series tank rides on a pair of Self-aligning spherical Bearings that allows the elevation and depression of the cannon. Because these Bearings are encapsulated within the rotor housing, periodic lubrication or maintenance is impossible. To overcome this problem Self-Lubricating Bearings were incorporated into the system. There are two basic liner designs, molded and fabric. Molded liners are produced by applying a formulation of teflon and typically asbestos into a phenolic resin, which is applied to the bearing surface, then cured. Fabric liners utilize a woven fabric bonded to the bearing surface, then teflon which is mixed into phenolic resin is applied to the bearing surface and cured. Initial studies of the existing bearing liner were completed to determine the liner composition and establish a baseline or standard to compare thermal and mechanical properties with potential vendors. DSC revealed an average teflon content of 39.53%, which varied significantly through...

  • Thermal behaviour of teflon/phenolic liners in Self-Lubricating Bearings
    Journal of thermal analysis, 1997
    Co-Authors: M F Fleszar
    Abstract:

    The gun system of the M1 series tank rides on a pair of Self-aligning spherical Bearings that allows the elevation and depression of the cannon. Because these Bearings are encapsulated within the rotor housing, periodic lubrication or maintenance is impossible. To overcome this problem Self-Lubricating Bearings were incorporated into the system. There are two basic liner designs, molded and fabric. Molded liners are produced by applying a formulation of teflon and typically asbestos into a phenolic resin, which is applied to the bearing surface, then cured. Fabric liners utilize a woven fabric bonded to the bearing surface, then teflon which is mixed into phenolic resin is applied to the bearing surface and cured. Initial studies of the existing bearing liner were completed to determine the liner composition and establish a baseline or standard to compare thermal and mechanical properties with potential vendors. DSC revealed an average teflon content of 39.53%, which varied significantly throughout the liner. TG analysis showed an asbestos concentration of 12.22%. The remainder of the liner was phenolic resin. Physical testing of the bearing from −20 to 120‡C under normal loading conditions demonstrated excellent thermal stability with little wear. Bearings from each vendor were tested and compared to the standard properties of the baseline bearing. Some properties were difficult to compare or insignificant due to the design differences between molded and fabric liners. The testing program resulted in the qualification of two Bearings, which met or exceeded the established standards. Both of these Bearings were designed with fabric liners.

Xiao Mei Huang - One of the best experts on this subject based on the ideXlab platform.

  • research on performance of mpia ptfe union fabric used as Self Lubricating Bearings liner
    Advanced Materials Research, 2013
    Co-Authors: Jing Gu, Xiao Mei Huang
    Abstract:

    Self-Lubricating Bearings liner is a fabric that can extend the period of use of spherical plain bearing. In this paper, the structural parameter of Self-Lubricating Bearings liner was discussed. Taking MPIA as warp, respectively the MPIA/PTFE twisting yarn and PET/PTFE twisting yarn as weft, we obtained 12 fabrics by changing the weft surface effect of fabric structure, linear density and twist of weft. Then, the wear resistance and frictional property of the fabrics were tested, and the relationship between the factors was analyzed. The data shows that the wear resistance and frictional properties of the fabric with change of different factors. In comprehensive, more suitable Self-Lubricating Bearings liner can be made by selecting MPIA and MPIA/PTFE twisting yarn intertwined, increasing weft surface effect, with moderate weft twist factor, and increasing weft linear density.

  • Research on Performance of MPIA/PTFE Union Fabric Used as Self-Lubricating Bearings Liner
    Advanced Materials Research, 2013
    Co-Authors: Jing Gu, Xiao Mei Huang
    Abstract:

    Self-Lubricating Bearings liner is a fabric that can extend the period of use of spherical plain bearing. In this paper, the structural parameter of Self-Lubricating Bearings liner was discussed. Taking MPIA as warp, respectively the MPIA/PTFE twisting yarn and PET/PTFE twisting yarn as weft, we obtained 12 fabrics by changing the weft surface effect of fabric structure, linear density and twist of weft. Then, the wear resistance and frictional property of the fabrics were tested, and the relationship between the factors was analyzed. The data shows that the wear resistance and frictional properties of the fabric with change of different factors. In comprehensive, more suitable Self-Lubricating Bearings liner can be made by selecting MPIA and MPIA/PTFE twisting yarn intertwined, increasing weft surface effect, with moderate weft twist factor, and increasing weft linear density.

Jing Gu - One of the best experts on this subject based on the ideXlab platform.

  • research on performance of mpia ptfe union fabric used as Self Lubricating Bearings liner
    Advanced Materials Research, 2013
    Co-Authors: Jing Gu, Xiao Mei Huang
    Abstract:

    Self-Lubricating Bearings liner is a fabric that can extend the period of use of spherical plain bearing. In this paper, the structural parameter of Self-Lubricating Bearings liner was discussed. Taking MPIA as warp, respectively the MPIA/PTFE twisting yarn and PET/PTFE twisting yarn as weft, we obtained 12 fabrics by changing the weft surface effect of fabric structure, linear density and twist of weft. Then, the wear resistance and frictional property of the fabrics were tested, and the relationship between the factors was analyzed. The data shows that the wear resistance and frictional properties of the fabric with change of different factors. In comprehensive, more suitable Self-Lubricating Bearings liner can be made by selecting MPIA and MPIA/PTFE twisting yarn intertwined, increasing weft surface effect, with moderate weft twist factor, and increasing weft linear density.

  • Research on Performance of MPIA/PTFE Union Fabric Used as Self-Lubricating Bearings Liner
    Advanced Materials Research, 2013
    Co-Authors: Jing Gu, Xiao Mei Huang
    Abstract:

    Self-Lubricating Bearings liner is a fabric that can extend the period of use of spherical plain bearing. In this paper, the structural parameter of Self-Lubricating Bearings liner was discussed. Taking MPIA as warp, respectively the MPIA/PTFE twisting yarn and PET/PTFE twisting yarn as weft, we obtained 12 fabrics by changing the weft surface effect of fabric structure, linear density and twist of weft. Then, the wear resistance and frictional property of the fabrics were tested, and the relationship between the factors was analyzed. The data shows that the wear resistance and frictional properties of the fabric with change of different factors. In comprehensive, more suitable Self-Lubricating Bearings liner can be made by selecting MPIA and MPIA/PTFE twisting yarn intertwined, increasing weft surface effect, with moderate weft twist factor, and increasing weft linear density.

Alastair Clarke - One of the best experts on this subject based on the ideXlab platform.

  • Damage detection of a composite bearing liner using Acoustic Emission.
    2017
    Co-Authors: Konstantinos Karras, Rhys Pullin, Roger Ivor Grosvenor, Alastair Clarke
    Abstract:

    Self-Lubricating Bearings are widely used within the aerospace industry and are commonly found, for example, in the pitch control assembly of a rotorcraft. Due to their high importance the components located within such systems are marked as critical parts and therefore the monitoring of their current health state is of great value. The bearing liner which provides the sliding surface between inner and outer races is a Polytetrafluoroethylene (PTFE) and glass fibre woven composite. Low friction coefficients are achieved via the deposition of PTFE third-body particles, which occupy the valley-features at the roughness scale on the non-conformal sliding surfaces. As these third-bodies form, the woven matrix composite surface layers containing PTFE are consumed up to a point where only the structural reinforcing glass fibres are present, resulting in a higher coefficient of friction and accelerating the wear process. A cylinder-on-flat oscillating wear test bench developed within Cardiff University allowed for the gathering of physical data including temperature and Acoustic Emission (AE) signals during an accelerated wear test of the liner material. A radial load of 2.5 kN and oscillation frequency of 5Hz were applied to replicate typical operating conditions within a pitch control system. Frequency analysis techniques were carried out on the AE data, successfully identifying the transition from healthy contact into the failure region.

  • Damage detection of a PTFE liner matrix composite through the use of acoustic emission
    2016
    Co-Authors: Konstantinos Karras, Rhys Pullin, Roger Ivor Grosvenor, Alastair Clarke
    Abstract:

    Self-Lubricating Bearings are widely used within the aerospace industry and are commonly found in the pitch control assembly of rotorcraft and, as such, are critical parts due to their importance within the system. The dry lubricant present within these Bearings acts as a consumable material which occupies the troughs of the inner race therefore forming a smooth sliding surface between inner and outer race via the deposition of third body particles. For this research the liner material is in the form of a woven composite, consisting of Polytetrafluoroethylene (PTFE) as the dry-lubricant and glass fibres as the reinforcing material, cured in a resin matrix. A cylinder-on-flat oscillating wear test bench developed within Cardiff University allowed for the gathering of physical data including temperature and Acoustic Emission (AE) signals during an accelerated wear test of the liner material. A radial load of 2.5 kN and oscillation frequency of 5Hz were applied to replicate typical operating conditions within a pitch control system. Frequency analysis techniques were carried out on the AE data, successfully identifying the transition from healthy contact into the failure region.

  • Wear testing of aerospace Self-Lubricating bearing liner materials [Abstract]
    2015
    Co-Authors: Alastair Clarke, Michael Colton, Konstantinos Karras, Rhys Pullin, Andrew Bell, Henry Peredur Evans, Samuel Lewin Evans
    Abstract:

    The paper describes a novel method for testing the wear rates of liner materials for Self-Lubricating Bearings. The apparatus differs from similar machines in that it is designed for reciprocating contact, to simulate motions encountered in helicopter main rotor pitch link Bearings, and is designed to test up to 4 samples at the same time, reducing the effect of variability in environmental conditions. This paper describes key aspects of the test rig along with initial results. Self-Lubricating Bearings have been in widespread use since the mid-1950s, predominantly in the aerospace industry where they have the advantage of being low maintenance components. They usually consist of a spherical bearing with the inner and outer elements separated by a composite glass fibre / PTFE resin-bonded textile liner. Previous work found that the wear of typical composite liners has three distinct phases – initial wear in, steady-state wear phase, final wear-out, and that humidity and environmental temperature can have a strong influence. Typical bearing-scale tests are long duration, and so a method of accounting for environmental factors and allowing the rapid screening of materials and test conditions is described here as an aid to technology development.

  • A simultaneous testing facility for aerospace Self-lubricated bearing liner materials
    2015
    Co-Authors: Alastair Clarke, Michael Colton, Rhys Pullin, Samuel Lewin Evans, Henry Peredur Evans, Andrew Bell
    Abstract:

    The paper describes a novel apparatus designed to test the wear rates of liner materials for Self-Lubricating Bearings. Self-Lubricating Bearings have been in widespread use since the mid-1950s, predominantly in the aerospace industry where they have the advantage of being low maintenance components. They are commonly used in reciprocating applications such as control surface actuators, and usually consist of a spherical bearing with the inner and outer elements separated by a composite resin-bonded textile liner. The apparatus differs from similar machines in that it is designed for reciprocating contact, to simulate motions encountered in helicopter main rotor pitch link Bearings. Additionally, it is designed to test up to 4 samples at the same time, reducing the effect of variability in environmental conditions such as temperature or humidity. This paper describes key aspects of the test rig along with initial results.

  • Modelling the wear behaviour of a Self-Lubricating composite bearing
    2014
    Co-Authors: Henry Peredur Evans, Alastair Clarke, Andrew Bell, Raymond Walter Snidle, Michael Colton
    Abstract:

    The paper describes a numerical model for estimating the progression of wear in a Self Lubricating spherical plain bearing over its useful wear life. Self-Lubricating Bearings have been in widespread use since the mid-1950s, predominantly in the aerospace industry where they have the advantage of being low maintenance components. They are commonly used in relatively low speed, reciprocating applications such as control surface actuators, and usually consist of a spherical bearing with the inner and outer elements separated by a composite textile resin-bonded liner. A mathematical model has been developed which can be used to predict the local contact pressures and wear rates in a composite bearing at different states of wear. Results from the model have been verified against full-scale bearing tests.

Andrew Bell - One of the best experts on this subject based on the ideXlab platform.

  • Wear testing of aerospace Self-Lubricating bearing liner materials [Abstract]
    2015
    Co-Authors: Alastair Clarke, Michael Colton, Konstantinos Karras, Rhys Pullin, Andrew Bell, Henry Peredur Evans, Samuel Lewin Evans
    Abstract:

    The paper describes a novel method for testing the wear rates of liner materials for Self-Lubricating Bearings. The apparatus differs from similar machines in that it is designed for reciprocating contact, to simulate motions encountered in helicopter main rotor pitch link Bearings, and is designed to test up to 4 samples at the same time, reducing the effect of variability in environmental conditions. This paper describes key aspects of the test rig along with initial results. Self-Lubricating Bearings have been in widespread use since the mid-1950s, predominantly in the aerospace industry where they have the advantage of being low maintenance components. They usually consist of a spherical bearing with the inner and outer elements separated by a composite glass fibre / PTFE resin-bonded textile liner. Previous work found that the wear of typical composite liners has three distinct phases – initial wear in, steady-state wear phase, final wear-out, and that humidity and environmental temperature can have a strong influence. Typical bearing-scale tests are long duration, and so a method of accounting for environmental factors and allowing the rapid screening of materials and test conditions is described here as an aid to technology development.

  • A simultaneous testing facility for aerospace Self-lubricated bearing liner materials
    2015
    Co-Authors: Alastair Clarke, Michael Colton, Rhys Pullin, Samuel Lewin Evans, Henry Peredur Evans, Andrew Bell
    Abstract:

    The paper describes a novel apparatus designed to test the wear rates of liner materials for Self-Lubricating Bearings. Self-Lubricating Bearings have been in widespread use since the mid-1950s, predominantly in the aerospace industry where they have the advantage of being low maintenance components. They are commonly used in reciprocating applications such as control surface actuators, and usually consist of a spherical bearing with the inner and outer elements separated by a composite resin-bonded textile liner. The apparatus differs from similar machines in that it is designed for reciprocating contact, to simulate motions encountered in helicopter main rotor pitch link Bearings. Additionally, it is designed to test up to 4 samples at the same time, reducing the effect of variability in environmental conditions such as temperature or humidity. This paper describes key aspects of the test rig along with initial results.

  • Modelling the wear behaviour of a Self-Lubricating composite bearing
    2014
    Co-Authors: Henry Peredur Evans, Alastair Clarke, Andrew Bell, Raymond Walter Snidle, Michael Colton
    Abstract:

    The paper describes a numerical model for estimating the progression of wear in a Self Lubricating spherical plain bearing over its useful wear life. Self-Lubricating Bearings have been in widespread use since the mid-1950s, predominantly in the aerospace industry where they have the advantage of being low maintenance components. They are commonly used in relatively low speed, reciprocating applications such as control surface actuators, and usually consist of a spherical bearing with the inner and outer elements separated by a composite textile resin-bonded liner. A mathematical model has been developed which can be used to predict the local contact pressures and wear rates in a composite bearing at different states of wear. Results from the model have been verified against full-scale bearing tests.

  • Modelling the variation of friction in a Self-Lubricating composite bearing due to wear
    2013
    Co-Authors: Henry Peredur Evans, Raymond Walter Snidle, Andrew Bell
    Abstract:

    The paper describes a numerical model for estimating the variation of the friction coefficient of a Self Lubricating bearing liner over its useful wear life. Self-Lubricating Bearings have been in widespread use since the mid-1950s, predominantly in the aerospace industry, where they have the advantage of being low maintenance components. They are predominantly used in relatively low speed, reciprocating applications such as control surface actuators, and usually consist of a spherical bearing with the inner and outer elements separated by a composite textile resin-bonded liner. A particular Self-Lubricating liner composition is analysed in this paper. A finite element model has been developed to predict the local stiffness of the liner at different states of wear. Results obtained using the model have then been used to predict the overall friction coefficient as it progresses due to wear. The predictions have been verified against rig tests of the liner material.