The Experts below are selected from a list of 63 Experts worldwide ranked by ideXlab platform

Sk Bhaumik - One of the best experts on this subject based on the ideXlab platform.

  • Failure analysis of components belonging to an aeroengine
    2008
    Co-Authors: M Sujata, Ma Venkataswamy, M.l. Madan, Sk Bhaumik
    Abstract:

    There was an incidence to an aircraft wherein the pilot heard a loud bang on accelerating throttle to max dry rpm at line up. After preliminary examination, a few suspected components of the damaged engine were forwarded to the laboratory for identification of mode and cause of failure. Examination revealed that failure of one of the first stage low-pressure compressor blades was the first in the chain of events that led to the engine failure. Fractographic examination showed that the compressor blade had failed by fatigue. The fatigue crack had initiated at the fillet of the blade Mounting Lug. Fatigue cracks were found present at the fillet of all four Mounting Lugs of this blade. Similar cracks were also noticed in two more blades adjacent to the fractured blade. It was established that the stress raisers arising due to absence of fillet radius was the primary reason for the fatigue crack initiation. The blade material and the microstructure were found to conform to specification. A detailed analysis of the failure is presented in this report.

  • Failure analysis of MGB and TGB housings of a helicopter
    2006
    Co-Authors: M Suresh Kumar, Ma Venkataswamy, Ma Parameswara, M Sujata, M.l. Madan, Sk Bhaumik
    Abstract:

    A fractured MGB housing and a cracked TGB housing belonging to a helicopter were forwarded to the laboratory for analyzing the causes of failures. The components were made of Mg-alloy of RZ-5 specification. Investigation revealed that both the components have failed by fatigue. The fatigue crack initiation in the Mounting Lugs of the MGB housing was stress related. It is believed that the component has experienced unexpected high loads at these Mounting locations, probably due to some abnormalities in the gearbox. However, this needs to be ascertained by detailed examination of the gearbox components. The fatigue crack initiation in the TGB housing was due to high stress concentration arising from a thin edge at the fillet region. The fatigue crack initiation was also facilitated because of wide difference in the length of the webs of the Mounting Lug, which was caused due to incorporation of a temperature sensor-locating boss at this location. It is recommended that the design aspects of the Lug be reviewed for a possible relocation of the temperature sensor-locating boss to a non-critical region or isolation of the boss from the attachment Lug.

  • Failure analysis of MGB housing of a helicopter
    National Aerospace Laboratories, 2005
    Co-Authors: Suresh Kumar M, Madan M, Sujata M, Sk Bhaumik
    Abstract:

    The Mounting Lug of the MGB housing of a helicopter has failed by fatigue. With the available evidences, it was not possible to establish the exact cause of the failure. Analysis shows that the fatigue crack initiation was due to one or more of the following reasons: (a) ovality in the Lug bore and/or bush, (b) excessive rotational torque on the MGB housing, and (c) improper fitment. No metallurgical abnormalities were responsible for the failure. The microstructure and chemical composition of the housing material were found to conform to RZ-5 specification

  • Fractographic examination of failed part of a cluster of body structure of a crashed helicopter
    2003
    Co-Authors: Ma Venkataswamy, Ma Parameswara, M Sujata, Barai Keshab, Sk Bhaumik
    Abstract:

    A sample pertaining to the Mounting Lug of ‘A’ frame at cluster 8D of body structure of accident helicopter was sent to the laboratory for fractographic analysis. It was requested not to carry out any destructive tests on the sample. Fractographic analysis suggests that the Lug in question has failed by sudden overload. There were no evidences of delayed failure like stress corrosion cracking or fatigue. The weld quality at the failed Lug was found to be poor. Insufficient fusion and lack of weld penetration were observed. However, these imperfections do not appear to have any role to play in the present failure.

J. L. Nowinski - One of the best experts on this subject based on the ideXlab platform.

  • Thermal Stresses in Severe Environments
    2011
    Co-Authors: D. P. H. Hasselman, R. A. Heller, J. L. Nowinski
    Abstract:

    Thermal Stresses: A Survey.- Thermoelasticity in Polymeric and Crystalline Solids from the Atomistic Viewpoint.- Thermoelasticity with Finite Wave Speeds.- Thermal Stresses: Transient and Permanent.- A Coupled, Isotropic Theory of Thermoviscoplasticity and Its Prediction for Stress and Strain Controlled Loading in Torsion.- The Effects of the Temperature-Dependence of Properties On the Thermal Stresses in Cylinders.- A Nonlinear Constitutive Relationship for Composite Propellants.- Thermal Stress and Fracture in Elastic-Brittle Materials.- On Calculating Thermally Induced Stress Singularities.- Thermomechanical Parameters due to Fire in Unsteady Heat-Conduction Analysis.- Thermoelastic Buckling of Plates in a Cylindrical Geometry Against an Elastic Back Support.- Stresses Due to Thermal Trapping in Semi-Absorbing Materials Subjected to Intense Radiation.- Instability of Parallel Thermal Cracks and Its Consequences for Hot Dry Rock Geothermal Energy.- Thermal Stresses in Coal Conversion Pressure Vessels Built of Layered Construction.- An Approach to Life Prediction of Domestic Gas Furnace Clam Shell Type Heat Exchangers.- Statistical Fracture Analysis of Brittle Materials in Thermally Stressed Components.- Thermally Induced Stresses in Insulating Cylinder Linings for Interal Combustion Engines.- Thermal Creep of Coke-Oven Jamb Frames.- A Study of Part Through Cracks in a Reactor Beltline Subjected to Thermal Shock.- Analyses of Mechanical and Thermal Stresses for Loft Densitometer Mounting Lug Assembly.- Thermal Stresses in Heat-Absorbing Building Glass Subjected to Solar Radiation.- Effect of Spatial Variation of Thermal Conductivity on Magnitude of Tensile Thermal Stress in Brittle Materials Subjected to Convective Heating.- Thermal Shock of Refractories.- Effect of Crack Healing on Thermal Stress Fracture.- Improvement of Thermal Shock Resistance of Brittle Structural Ceramics by a Dispersed Phase of Zirconia.- Dependence of Thermal Stress Resistance on Material Parameters: Ceramic Composite Systems.- Thermal Stress in Cylindrical Glass Seals in Microelectronic Packaging Under Thermal Shock.- Reliability Analysis of Thermally Stressed Viscoelastic Structures by Monte-Carlo Simulation.- Propagation of Propellant-Linear Separations in Rocket Motor Grains Under Transient Thermal Loading.- Thermoviscoelastic Interaction Effects in Filled Polymers.- Allowable Strength of Viscoelastic Materials Under Variable Thermal Loads.- Failure Probability Evaluation of an Anisotropic Brittle Structure Derived from a Thermal Stress Solution.- Estimate of Storage Life for M392/M728 Projectiles Based on Finite Element Thermal Stress Analysis.- Determination of the Thermal Shock Fracture Toughness of Reactor Graphite Subjected to Neutron Irradiation at High Temperature.- Thermal Stress Testing of Advanced Optical Ceramics by a Laser Technique.- Laser Induced Thermal Stresses in Brittle Materials.- Investigation of Thermal Shock Resistance of Ceramic Materials Under Programmed Heating.- Thermal Deformations and Stresses in Composite Materials.- Residual Stresses and Microcracking Induced by Thermal Contraction Inhomogeneity.- Thermal Microcracking in Celion 6000/PMR-15 Graphite/Polyimide.- External Crack Due to Thermal Effects in an Infinite Elastic Solid with a Cylindrical Inclusion.- The Viscoelastic Behavior of a Composite in a Thermal Environment.- Stress Related Thermal Emission.- Contributors.

D. P. H. Hasselman - One of the best experts on this subject based on the ideXlab platform.

  • Thermal Stresses in Severe Environments
    2011
    Co-Authors: D. P. H. Hasselman, R. A. Heller, J. L. Nowinski
    Abstract:

    Thermal Stresses: A Survey.- Thermoelasticity in Polymeric and Crystalline Solids from the Atomistic Viewpoint.- Thermoelasticity with Finite Wave Speeds.- Thermal Stresses: Transient and Permanent.- A Coupled, Isotropic Theory of Thermoviscoplasticity and Its Prediction for Stress and Strain Controlled Loading in Torsion.- The Effects of the Temperature-Dependence of Properties On the Thermal Stresses in Cylinders.- A Nonlinear Constitutive Relationship for Composite Propellants.- Thermal Stress and Fracture in Elastic-Brittle Materials.- On Calculating Thermally Induced Stress Singularities.- Thermomechanical Parameters due to Fire in Unsteady Heat-Conduction Analysis.- Thermoelastic Buckling of Plates in a Cylindrical Geometry Against an Elastic Back Support.- Stresses Due to Thermal Trapping in Semi-Absorbing Materials Subjected to Intense Radiation.- Instability of Parallel Thermal Cracks and Its Consequences for Hot Dry Rock Geothermal Energy.- Thermal Stresses in Coal Conversion Pressure Vessels Built of Layered Construction.- An Approach to Life Prediction of Domestic Gas Furnace Clam Shell Type Heat Exchangers.- Statistical Fracture Analysis of Brittle Materials in Thermally Stressed Components.- Thermally Induced Stresses in Insulating Cylinder Linings for Interal Combustion Engines.- Thermal Creep of Coke-Oven Jamb Frames.- A Study of Part Through Cracks in a Reactor Beltline Subjected to Thermal Shock.- Analyses of Mechanical and Thermal Stresses for Loft Densitometer Mounting Lug Assembly.- Thermal Stresses in Heat-Absorbing Building Glass Subjected to Solar Radiation.- Effect of Spatial Variation of Thermal Conductivity on Magnitude of Tensile Thermal Stress in Brittle Materials Subjected to Convective Heating.- Thermal Shock of Refractories.- Effect of Crack Healing on Thermal Stress Fracture.- Improvement of Thermal Shock Resistance of Brittle Structural Ceramics by a Dispersed Phase of Zirconia.- Dependence of Thermal Stress Resistance on Material Parameters: Ceramic Composite Systems.- Thermal Stress in Cylindrical Glass Seals in Microelectronic Packaging Under Thermal Shock.- Reliability Analysis of Thermally Stressed Viscoelastic Structures by Monte-Carlo Simulation.- Propagation of Propellant-Linear Separations in Rocket Motor Grains Under Transient Thermal Loading.- Thermoviscoelastic Interaction Effects in Filled Polymers.- Allowable Strength of Viscoelastic Materials Under Variable Thermal Loads.- Failure Probability Evaluation of an Anisotropic Brittle Structure Derived from a Thermal Stress Solution.- Estimate of Storage Life for M392/M728 Projectiles Based on Finite Element Thermal Stress Analysis.- Determination of the Thermal Shock Fracture Toughness of Reactor Graphite Subjected to Neutron Irradiation at High Temperature.- Thermal Stress Testing of Advanced Optical Ceramics by a Laser Technique.- Laser Induced Thermal Stresses in Brittle Materials.- Investigation of Thermal Shock Resistance of Ceramic Materials Under Programmed Heating.- Thermal Deformations and Stresses in Composite Materials.- Residual Stresses and Microcracking Induced by Thermal Contraction Inhomogeneity.- Thermal Microcracking in Celion 6000/PMR-15 Graphite/Polyimide.- External Crack Due to Thermal Effects in an Infinite Elastic Solid with a Cylindrical Inclusion.- The Viscoelastic Behavior of a Composite in a Thermal Environment.- Stress Related Thermal Emission.- Contributors.

Ma Venkataswamy - One of the best experts on this subject based on the ideXlab platform.

  • Failure analysis of components belonging to an aeroengine
    2008
    Co-Authors: M Sujata, Ma Venkataswamy, M.l. Madan, Sk Bhaumik
    Abstract:

    There was an incidence to an aircraft wherein the pilot heard a loud bang on accelerating throttle to max dry rpm at line up. After preliminary examination, a few suspected components of the damaged engine were forwarded to the laboratory for identification of mode and cause of failure. Examination revealed that failure of one of the first stage low-pressure compressor blades was the first in the chain of events that led to the engine failure. Fractographic examination showed that the compressor blade had failed by fatigue. The fatigue crack had initiated at the fillet of the blade Mounting Lug. Fatigue cracks were found present at the fillet of all four Mounting Lugs of this blade. Similar cracks were also noticed in two more blades adjacent to the fractured blade. It was established that the stress raisers arising due to absence of fillet radius was the primary reason for the fatigue crack initiation. The blade material and the microstructure were found to conform to specification. A detailed analysis of the failure is presented in this report.

  • Failure analysis of MGB and TGB housings of a helicopter
    2006
    Co-Authors: M Suresh Kumar, Ma Venkataswamy, Ma Parameswara, M Sujata, M.l. Madan, Sk Bhaumik
    Abstract:

    A fractured MGB housing and a cracked TGB housing belonging to a helicopter were forwarded to the laboratory for analyzing the causes of failures. The components were made of Mg-alloy of RZ-5 specification. Investigation revealed that both the components have failed by fatigue. The fatigue crack initiation in the Mounting Lugs of the MGB housing was stress related. It is believed that the component has experienced unexpected high loads at these Mounting locations, probably due to some abnormalities in the gearbox. However, this needs to be ascertained by detailed examination of the gearbox components. The fatigue crack initiation in the TGB housing was due to high stress concentration arising from a thin edge at the fillet region. The fatigue crack initiation was also facilitated because of wide difference in the length of the webs of the Mounting Lug, which was caused due to incorporation of a temperature sensor-locating boss at this location. It is recommended that the design aspects of the Lug be reviewed for a possible relocation of the temperature sensor-locating boss to a non-critical region or isolation of the boss from the attachment Lug.

  • Fractographic examination of failed part of a cluster of body structure of a crashed helicopter
    2003
    Co-Authors: Ma Venkataswamy, Ma Parameswara, M Sujata, Barai Keshab, Sk Bhaumik
    Abstract:

    A sample pertaining to the Mounting Lug of ‘A’ frame at cluster 8D of body structure of accident helicopter was sent to the laboratory for fractographic analysis. It was requested not to carry out any destructive tests on the sample. Fractographic analysis suggests that the Lug in question has failed by sudden overload. There were no evidences of delayed failure like stress corrosion cracking or fatigue. The weld quality at the failed Lug was found to be poor. Insufficient fusion and lack of weld penetration were observed. However, these imperfections do not appear to have any role to play in the present failure.

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

  • Failure analysis of components belonging to an aeroengine
    2008
    Co-Authors: M Sujata, Ma Venkataswamy, M.l. Madan, Sk Bhaumik
    Abstract:

    There was an incidence to an aircraft wherein the pilot heard a loud bang on accelerating throttle to max dry rpm at line up. After preliminary examination, a few suspected components of the damaged engine were forwarded to the laboratory for identification of mode and cause of failure. Examination revealed that failure of one of the first stage low-pressure compressor blades was the first in the chain of events that led to the engine failure. Fractographic examination showed that the compressor blade had failed by fatigue. The fatigue crack had initiated at the fillet of the blade Mounting Lug. Fatigue cracks were found present at the fillet of all four Mounting Lugs of this blade. Similar cracks were also noticed in two more blades adjacent to the fractured blade. It was established that the stress raisers arising due to absence of fillet radius was the primary reason for the fatigue crack initiation. The blade material and the microstructure were found to conform to specification. A detailed analysis of the failure is presented in this report.

  • Failure analysis of MGB and TGB housings of a helicopter
    2006
    Co-Authors: M Suresh Kumar, Ma Venkataswamy, Ma Parameswara, M Sujata, M.l. Madan, Sk Bhaumik
    Abstract:

    A fractured MGB housing and a cracked TGB housing belonging to a helicopter were forwarded to the laboratory for analyzing the causes of failures. The components were made of Mg-alloy of RZ-5 specification. Investigation revealed that both the components have failed by fatigue. The fatigue crack initiation in the Mounting Lugs of the MGB housing was stress related. It is believed that the component has experienced unexpected high loads at these Mounting locations, probably due to some abnormalities in the gearbox. However, this needs to be ascertained by detailed examination of the gearbox components. The fatigue crack initiation in the TGB housing was due to high stress concentration arising from a thin edge at the fillet region. The fatigue crack initiation was also facilitated because of wide difference in the length of the webs of the Mounting Lug, which was caused due to incorporation of a temperature sensor-locating boss at this location. It is recommended that the design aspects of the Lug be reviewed for a possible relocation of the temperature sensor-locating boss to a non-critical region or isolation of the boss from the attachment Lug.

  • Fractographic examination of failed part of a cluster of body structure of a crashed helicopter
    2003
    Co-Authors: Ma Venkataswamy, Ma Parameswara, M Sujata, Barai Keshab, Sk Bhaumik
    Abstract:

    A sample pertaining to the Mounting Lug of ‘A’ frame at cluster 8D of body structure of accident helicopter was sent to the laboratory for fractographic analysis. It was requested not to carry out any destructive tests on the sample. Fractographic analysis suggests that the Lug in question has failed by sudden overload. There were no evidences of delayed failure like stress corrosion cracking or fatigue. The weld quality at the failed Lug was found to be poor. Insufficient fusion and lack of weld penetration were observed. However, these imperfections do not appear to have any role to play in the present failure.