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S P H Marashi - One of the best experts on this subject based on the ideXlab platform.
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Failure Mode transition in ahss resistance spot welds part i controlling factors
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2011Co-Authors: M Pouranvari, S P H MarashiAbstract:Abstract Failure Mode of resistance spot welds is a qualitative indicator of weld performance. Two major types of spot weld Failure are pull-out and interfacial fracture. Interfacial Failure, which typically results in reduced energy absorption capability, is considered unsatisfactory and industry standards are often designed to avoid this occurrence. Advanced High Strength Steel (AHSS) spot welds exhibit high tendency to fail in interfacial Failure Mode. Sizing of spot welds based on the conventional recommendation of 4t0.5 (t is sheet thickness) does not guarantee the pullout Failure Mode in many cases of AHSS spot welds. Therefore, a new weld quality criterion should be found for AHSS resistance spot welds to guarantee pull-out Failure. The aim of this paper is to investigate and analyze the transition between interfacial and pull-out Failure Modes in AHSS resistance spot welds during the tensile–shear test by the use of analytical approach. In this work, in the light of Failure mechanism, a simple analytical Model is presented for estimating the critical fusion zone size to prevent interfacial fracture. According to this Model, the hardness ratio of fusion zone to pull-out Failure location and the volume fraction of voids in fusion zone are the key metallurgical factors governing type of Failure Mode of AHSS spot welds during the tensile–shear test. Low hardness ratio and high susceptibility to form shrinkage voids in the case of AHSS spot welds appear to be the two primary causes for their high tendency to fail in interfacial Mode.
M Pouranvari - One of the best experts on this subject based on the ideXlab platform.
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Failure Mode transition in ahss resistance spot welds part i controlling factors
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2011Co-Authors: M Pouranvari, S P H MarashiAbstract:Abstract Failure Mode of resistance spot welds is a qualitative indicator of weld performance. Two major types of spot weld Failure are pull-out and interfacial fracture. Interfacial Failure, which typically results in reduced energy absorption capability, is considered unsatisfactory and industry standards are often designed to avoid this occurrence. Advanced High Strength Steel (AHSS) spot welds exhibit high tendency to fail in interfacial Failure Mode. Sizing of spot welds based on the conventional recommendation of 4t0.5 (t is sheet thickness) does not guarantee the pullout Failure Mode in many cases of AHSS spot welds. Therefore, a new weld quality criterion should be found for AHSS resistance spot welds to guarantee pull-out Failure. The aim of this paper is to investigate and analyze the transition between interfacial and pull-out Failure Modes in AHSS resistance spot welds during the tensile–shear test by the use of analytical approach. In this work, in the light of Failure mechanism, a simple analytical Model is presented for estimating the critical fusion zone size to prevent interfacial fracture. According to this Model, the hardness ratio of fusion zone to pull-out Failure location and the volume fraction of voids in fusion zone are the key metallurgical factors governing type of Failure Mode of AHSS spot welds during the tensile–shear test. Low hardness ratio and high susceptibility to form shrinkage voids in the case of AHSS spot welds appear to be the two primary causes for their high tendency to fail in interfacial Mode.
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effect of weld nugget size on overload Failure Mode of resistance spot welds
Science and Technology of Welding and Joining, 2007Co-Authors: M Pouranvari, H R Asgari, S M Mosavizadch, Pirooz Marashi, M GoodarziAbstract:AbstractIn the present paper, effects of welding current, welding time, electrode pressure and holding time on the weld nugget size were studied. A Failure mechanism was proposed to describe both interfacial and pullout Failure Modes. This mechanism was confirmed by SEM investigations. In the light of this mechanism, the effect of welding parameters on static weld strength and Failure Mode was studied. Then, an analytical Model was proposed to predict Failure Mode and to estimate minimum nugget diameter (critical diameter) to ensure pullout Failure Mode in shear tensile test. On the contrary to existing industrial standards, in this Model, critical nugget diameter is attributed to metallurgical characterisation of material (weld nugget hardness to Failure location hardness ratio), in addition to sheet thickness. For a given sheet thickness, decreasing HWN/HFL increases interfacial Failure Mode tendency. The results of this Model were compared with experimental data and also with the literature.
V. Kishorenath - One of the best experts on this subject based on the ideXlab platform.
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Failure Mode Avoidance of Solid Rocket Motor Pressure Monitoring Joint Seals
Journal of Failure Analysis and Prevention, 2017Co-Authors: V. Murugesan, P. S. Sreejith, A. K. Anilkumar, V. KishorenathAbstract:The sealing joints used for pressure monitoring of solid propellant rocket motors (SRMs) of launch vehicles are very critical, as they are large in number, and leak through any of them is a single point Failure Mode. Identification of Failure Modes and its prevention is the key for reliable performance of an SRM. Failure Modes are identified and the Failure mechanisms of different seals in the pressure monitoring system studied through investigative tests with deliberately induced variations in the design parameters and nonconformance. Systematic analysis is carried out for the proposed designs through a Failure Mode effects analysis (FMEA), Failure Modes ranked in accordance with Risk Priority Number (RPN) and reliability of the joints worked out from the data. Design concerns are analyzed, alternate designs explored and innovative design solutions evolved. The effectiveness of the final design is brought out quantitatively by reduced RPN ratings and quantum jump in the reliability. Critical design, process and quality control parameters were identified, and procedures to ensure them evolved for Failure Mode avoidance.
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Failure Mode Avoidance of Solid Rocket Motor Pressure Monitoring Joint Seals
Journal of Failure Analysis and Prevention, 2017Co-Authors: V. Murugesan, P. S. Sreejith, A. K. Anilkumar, V. KishorenathAbstract:The sealing joints used for pressure monitoring of solid propellant rocket motors (SRMs) of launch vehicles are very critical, as they are large in number, and leak through any of them is a single point Failure Mode. Identification of Failure Modes and its prevention is the key for reliable performance of an SRM. Failure Modes are identified and the Failure mechanisms of different seals in the pressure monitoring system studied through investigative tests with deliberately induced variations in the design parameters and nonconformance. Systematic analysis is carried out for the proposed designs through a Failure Mode effects analysis (FMEA), Failure Modes ranked in accordance with Risk Priority Number (RPN) and reliability of the joints worked out from the data. Design concerns are analyzed, alternate designs explored and innovative design solutions evolved. The effectiveness of the final design is brought out quantitatively by reduced RPN ratings and quantum jump in the reliability. Critical design, process and quality control parameters were identified, and procedures to ensure them evolved for Failure Mode avoidance.
V. Murugesan - One of the best experts on this subject based on the ideXlab platform.
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Failure Mode Avoidance of Solid Rocket Motor Pressure Monitoring Joint Seals
Journal of Failure Analysis and Prevention, 2017Co-Authors: V. Murugesan, P. S. Sreejith, A. K. Anilkumar, V. KishorenathAbstract:The sealing joints used for pressure monitoring of solid propellant rocket motors (SRMs) of launch vehicles are very critical, as they are large in number, and leak through any of them is a single point Failure Mode. Identification of Failure Modes and its prevention is the key for reliable performance of an SRM. Failure Modes are identified and the Failure mechanisms of different seals in the pressure monitoring system studied through investigative tests with deliberately induced variations in the design parameters and nonconformance. Systematic analysis is carried out for the proposed designs through a Failure Mode effects analysis (FMEA), Failure Modes ranked in accordance with Risk Priority Number (RPN) and reliability of the joints worked out from the data. Design concerns are analyzed, alternate designs explored and innovative design solutions evolved. The effectiveness of the final design is brought out quantitatively by reduced RPN ratings and quantum jump in the reliability. Critical design, process and quality control parameters were identified, and procedures to ensure them evolved for Failure Mode avoidance.
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Failure Mode Avoidance of Solid Rocket Motor Pressure Monitoring Joint Seals
Journal of Failure Analysis and Prevention, 2017Co-Authors: V. Murugesan, P. S. Sreejith, A. K. Anilkumar, V. KishorenathAbstract:The sealing joints used for pressure monitoring of solid propellant rocket motors (SRMs) of launch vehicles are very critical, as they are large in number, and leak through any of them is a single point Failure Mode. Identification of Failure Modes and its prevention is the key for reliable performance of an SRM. Failure Modes are identified and the Failure mechanisms of different seals in the pressure monitoring system studied through investigative tests with deliberately induced variations in the design parameters and nonconformance. Systematic analysis is carried out for the proposed designs through a Failure Mode effects analysis (FMEA), Failure Modes ranked in accordance with Risk Priority Number (RPN) and reliability of the joints worked out from the data. Design concerns are analyzed, alternate designs explored and innovative design solutions evolved. The effectiveness of the final design is brought out quantitatively by reduced RPN ratings and quantum jump in the reliability. Critical design, process and quality control parameters were identified, and procedures to ensure them evolved for Failure Mode avoidance.
P. S. Sreejith - One of the best experts on this subject based on the ideXlab platform.
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Failure Mode Avoidance of Solid Rocket Motor Pressure Monitoring Joint Seals
Journal of Failure Analysis and Prevention, 2017Co-Authors: V. Murugesan, P. S. Sreejith, A. K. Anilkumar, V. KishorenathAbstract:The sealing joints used for pressure monitoring of solid propellant rocket motors (SRMs) of launch vehicles are very critical, as they are large in number, and leak through any of them is a single point Failure Mode. Identification of Failure Modes and its prevention is the key for reliable performance of an SRM. Failure Modes are identified and the Failure mechanisms of different seals in the pressure monitoring system studied through investigative tests with deliberately induced variations in the design parameters and nonconformance. Systematic analysis is carried out for the proposed designs through a Failure Mode effects analysis (FMEA), Failure Modes ranked in accordance with Risk Priority Number (RPN) and reliability of the joints worked out from the data. Design concerns are analyzed, alternate designs explored and innovative design solutions evolved. The effectiveness of the final design is brought out quantitatively by reduced RPN ratings and quantum jump in the reliability. Critical design, process and quality control parameters were identified, and procedures to ensure them evolved for Failure Mode avoidance.
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Failure Mode Avoidance of Solid Rocket Motor Pressure Monitoring Joint Seals
Journal of Failure Analysis and Prevention, 2017Co-Authors: V. Murugesan, P. S. Sreejith, A. K. Anilkumar, V. KishorenathAbstract:The sealing joints used for pressure monitoring of solid propellant rocket motors (SRMs) of launch vehicles are very critical, as they are large in number, and leak through any of them is a single point Failure Mode. Identification of Failure Modes and its prevention is the key for reliable performance of an SRM. Failure Modes are identified and the Failure mechanisms of different seals in the pressure monitoring system studied through investigative tests with deliberately induced variations in the design parameters and nonconformance. Systematic analysis is carried out for the proposed designs through a Failure Mode effects analysis (FMEA), Failure Modes ranked in accordance with Risk Priority Number (RPN) and reliability of the joints worked out from the data. Design concerns are analyzed, alternate designs explored and innovative design solutions evolved. The effectiveness of the final design is brought out quantitatively by reduced RPN ratings and quantum jump in the reliability. Critical design, process and quality control parameters were identified, and procedures to ensure them evolved for Failure Mode avoidance.
