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Reji John - One of the best experts on this subject based on the ideXlab platform.
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tensile creep and fatigue of sylramic ibn melt infiltrated sic matrix composites retained properties damage development and failure mechanisms
Composites Science and Technology, 2008Co-Authors: Gregory N. Morscher, Jalees Ahmad, Unni Santhosh, Robert Miller, Greg Ojard, Yasser Gowayed, Reji JohnAbstract:Abstract An understanding of the elevated temperature tensile creep, fatigue, rupture, and retained properties of ceramic matrix composites (CMC) envisioned for use in gas turbine engine applications is essential for component design and life-prediction. In order to quantify the effect of stress, time, temperature, and oxidation for a state-of-the-art composite system, a wide variety of tensile creep, dwell fatigue, and cyclic fatigue experiments were performed in air at 1204 °C for the SiC/SiC CMC system consisting of Sylramic-iBN SiC fibers, BN fiber interphase coating, and slurry-cast melt-infiltrated (MI) SiC-based matrix. Tests were either taken to failure or interrupted. Interrupted tests were then mechanically tested at room temperature to determine the residual properties. The retained properties of most of the composites subjected to tensile creep or fatigue were usually within 20% of the as-produced strength and 10% of the as-produced elastic modulus. It was observed that during creep, residual stresses in the composite are altered to some extent which results in an increased compressive stress in the matrix upon cooling and a subsequent increased stress required to form matrix cracks. Microscopy of polished sections and the fracture surfaces of specimens which failed during stressed-oxidation or after the room-temperature retained property test was performed on some of the specimens in order to quantify the nature and extent of damage accumulation that occurred during the test. It was discovered that the distribution of stress-dependent matrix cracking at 1204 °C was similar to the as-produced composites at room temperature; however, matrix crack growth occurred over time and typically did not appear to propagate through-the-thickness except at the final failure crack. Failure of the composites was due to either oxidation-induced unbridged crack growth, which dominated the higher stress regime (⩾179 MPa) or controlled by degradation of the fibers, probably caused by intrinsic creep-induced flaw growth of the fibers or Internal Attack of the fibers via Si diffusion through the CVI SiC and/or microcracks at the lower stress regime (⩽165 MPa).
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Tensile creep and fatigue of Sylramic-iBN melt-infiltrated SiC matrix composites: Retained properties, damage development, and failure mechanisms
Composites Science and Technology, 2008Co-Authors: Gregory N. Morscher, Jalees Ahmad, Unni Santhosh, Robert Miller, Greg Ojard, Yasser Gowayed, Reji JohnAbstract:An understanding of the elevated temperature tensile creep, fatigue, rupture, and retained properties of ceramic matrix composites (CMC) envisioned for use in gas turbine engine applications is essential for component design and life-prediction. In order to quantify the effect of stress, time, temperature, and oxidation for a state-of-the-art composite system, a wide variety of tensile creep, dwell fatigue, and cyclic fatigue experiments were performed in air at 1204 °C for the SiC/SiC CMC system consisting of Sylramic-iBN SiC fibers, BN fiber interphase coating, and slurry-cast melt-infiltrated (MI) SiC-based matrix. Tests were either taken to failure or interrupted. Interrupted tests were then mechanically tested at room temperature to determine the residual properties. The retained properties of most of the composites subjected to tensile creep or fatigue were usually within 20% of the as-produced strength and 10% of the as-produced elastic modulus. It was observed that during creep, residual stresses in the composite are altered to some extent which results in an increased compressive stress in the matrix upon cooling and a subsequent increased stress required to form matrix cracks. Microscopy of polished sections and the fracture surfaces of specimens which failed during stressed-oxidation or after the room-temperature retained property test was performed on some of the specimens in order to quantify the nature and extent of damage accumulation that occurred during the test. It was discovered that the distribution of stress-dependent matrix cracking at 1204 °C was similar to the as-produced composites at room temperature; however, matrix crack growth occurred over time and typically did not appear to propagate through-the-thickness except at the final failure crack. Failure of the composites was due to either oxidation-induced unbridged crack growth, which dominated the higher stress regime (≥179 MPa) or controlled by degradation of the fibers, probably caused by intrinsic creep-induced flaw growth of the fibers or Internal Attack of the fibers via Si diffusion through the CVI SiC and/or microcracks at the lower stress regime (≤165 MPa). © 2008 Elsevier Ltd.
Gregory N. Morscher - One of the best experts on this subject based on the ideXlab platform.
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tensile creep and fatigue of sylramic ibn melt infiltrated sic matrix composites retained properties damage development and failure mechanisms
Composites Science and Technology, 2008Co-Authors: Gregory N. Morscher, Jalees Ahmad, Unni Santhosh, Robert Miller, Greg Ojard, Yasser Gowayed, Reji JohnAbstract:Abstract An understanding of the elevated temperature tensile creep, fatigue, rupture, and retained properties of ceramic matrix composites (CMC) envisioned for use in gas turbine engine applications is essential for component design and life-prediction. In order to quantify the effect of stress, time, temperature, and oxidation for a state-of-the-art composite system, a wide variety of tensile creep, dwell fatigue, and cyclic fatigue experiments were performed in air at 1204 °C for the SiC/SiC CMC system consisting of Sylramic-iBN SiC fibers, BN fiber interphase coating, and slurry-cast melt-infiltrated (MI) SiC-based matrix. Tests were either taken to failure or interrupted. Interrupted tests were then mechanically tested at room temperature to determine the residual properties. The retained properties of most of the composites subjected to tensile creep or fatigue were usually within 20% of the as-produced strength and 10% of the as-produced elastic modulus. It was observed that during creep, residual stresses in the composite are altered to some extent which results in an increased compressive stress in the matrix upon cooling and a subsequent increased stress required to form matrix cracks. Microscopy of polished sections and the fracture surfaces of specimens which failed during stressed-oxidation or after the room-temperature retained property test was performed on some of the specimens in order to quantify the nature and extent of damage accumulation that occurred during the test. It was discovered that the distribution of stress-dependent matrix cracking at 1204 °C was similar to the as-produced composites at room temperature; however, matrix crack growth occurred over time and typically did not appear to propagate through-the-thickness except at the final failure crack. Failure of the composites was due to either oxidation-induced unbridged crack growth, which dominated the higher stress regime (⩾179 MPa) or controlled by degradation of the fibers, probably caused by intrinsic creep-induced flaw growth of the fibers or Internal Attack of the fibers via Si diffusion through the CVI SiC and/or microcracks at the lower stress regime (⩽165 MPa).
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Tensile creep and fatigue of Sylramic-iBN melt-infiltrated SiC matrix composites: Retained properties, damage development, and failure mechanisms
Composites Science and Technology, 2008Co-Authors: Gregory N. Morscher, Jalees Ahmad, Unni Santhosh, Robert Miller, Greg Ojard, Yasser Gowayed, Reji JohnAbstract:An understanding of the elevated temperature tensile creep, fatigue, rupture, and retained properties of ceramic matrix composites (CMC) envisioned for use in gas turbine engine applications is essential for component design and life-prediction. In order to quantify the effect of stress, time, temperature, and oxidation for a state-of-the-art composite system, a wide variety of tensile creep, dwell fatigue, and cyclic fatigue experiments were performed in air at 1204 °C for the SiC/SiC CMC system consisting of Sylramic-iBN SiC fibers, BN fiber interphase coating, and slurry-cast melt-infiltrated (MI) SiC-based matrix. Tests were either taken to failure or interrupted. Interrupted tests were then mechanically tested at room temperature to determine the residual properties. The retained properties of most of the composites subjected to tensile creep or fatigue were usually within 20% of the as-produced strength and 10% of the as-produced elastic modulus. It was observed that during creep, residual stresses in the composite are altered to some extent which results in an increased compressive stress in the matrix upon cooling and a subsequent increased stress required to form matrix cracks. Microscopy of polished sections and the fracture surfaces of specimens which failed during stressed-oxidation or after the room-temperature retained property test was performed on some of the specimens in order to quantify the nature and extent of damage accumulation that occurred during the test. It was discovered that the distribution of stress-dependent matrix cracking at 1204 °C was similar to the as-produced composites at room temperature; however, matrix crack growth occurred over time and typically did not appear to propagate through-the-thickness except at the final failure crack. Failure of the composites was due to either oxidation-induced unbridged crack growth, which dominated the higher stress regime (≥179 MPa) or controlled by degradation of the fibers, probably caused by intrinsic creep-induced flaw growth of the fibers or Internal Attack of the fibers via Si diffusion through the CVI SiC and/or microcracks at the lower stress regime (≤165 MPa). © 2008 Elsevier Ltd.
Xu Huang - One of the best experts on this subject based on the ideXlab platform.
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Evidentiary assessment for protecting WSNs from Internal Attacks in real-time
International Journal of Computers and Applications, 2016Co-Authors: Xu Huang, Raul Fernandez Rojas, Allan C. Madoc, Dua’a AhmadAbstract:AbstractWireless sensor networks (WSNs) are becoming a vital role in our current modern life for detecting and collecting data about a natural or built environment, including human body. One of the reasons is due to WSNs have very attractive advantages. But one of the problems is Internal Attacks that have gained prominence and posed most challenging threats to all WSNs. In this paper, we extend our discussion at the conference of the AISC 2016 to an effective algorithm to make an evaluation for detecting Internal Attack by evidentiary assessment for protecting a WSN from the Internal Attacks with multi-criteria in real-time. This protecting is based on the combination of the multiple pieces of evidences collected from the nodes suffering from an Internal Attacker in a network. A decision made is carefully discussed based on the Dempster–Shafer Theory (DST). One of the advantages of this proposed method is that it is not just making a performance in real-time but also it is effective due to it does not ne...
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ACE/ACSC/AISC/APCMM/AUIC/AWC - Effective algorithm for protecting WSNs from Internal Attacks in real-time
Proceedings of the Australasian Computer Science Week Multiconference on - ACSW '16, 2016Co-Authors: Xu Huang, Muhammad R. Ahmed, Raul Fernandez Rojas, Mohammed AseeriAbstract:Wireless sensor networks (WSNs) are playing a vital role in collecting data about a natural or built environment. WSNs have attractive advantages such as low-cost, low maintains and flexible arrangements for applications. Wireless sensor network has been used for many different applications such as military implementations in a battlefield, an environmental monitoring, and multifunction in health sector. In order to ensure its functionality, especially in malicious environments, security mechanisms become essential. Especially Internal Attacks have gained prominence and pose most challenging threats to all WSNs. Although, a number of works have been done to discuss a WSN under the Internal Attacks it has gained little attention. For example, the conventional cryptographic technique does not give the appropriated security to save the network from Internal Attack that causes by abnormally behaviour at the legitimate nodes in a network. In this paper, we propose an effective algorithm to make an evaluation for detecting Internal Attack by multi-criteria in real time. This protecting is based on the combination of the multiple pieces of evidences collected from the nodes under an Internal Attacker in a network. A theory of the decision is carefully discussed based on the Dempster-Shafer Theory (DST). If you really wanted to make sure the designed network works exactly works as you expected, you will be benefited from this algorithm. The advantage of this proposed method is not just its performance in real-time but also it is effective as it does not need the knowledge about the normal or malicious node in advance with very high average accuracy that is close to 100%. It also can be used as one of maintaining tools for the regulations of the deployed WSNs.
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Smart integration of cloud computing and MCMC based secured WSN to monitor environment
2014 4th International Conference on Wireless Communications Vehicular Technology Information Theory and Aerospace & Electronic Systems (VITAE), 2014Co-Authors: Muhammad R. Ahmed, Xu HuangAbstract:Wireless Sensor Network (WSN) is a low cost and multifunctional emerging technology. Its application ranges from military, health sector, environmental monitoring and industrial application. The maximum benefit of recent technology development can be achieved by integration internet (Cloud Computing) and secured real time data collection platform (secured-WSNs). In order to ensure its functionality especially in malicious environments, security mechanisms are essential in WSNs. Malicious or Internal Attacker has gained prominence and poses the most challenging Attacks to WSN. So, for complete security Internal Attacks need to be handled. In this paper we proposed content-based publish/subscribe (pub/sub) broker model on the Cloud that integrates WSNs to Cloud efficiently and effectively. To secure WSNs we have proposed a new approach for detecting Internal Attack by using Markov Chain Monte Carlo (MCMC). It is an efficient real time algorithm. It is good for sensor network as it operates with no or incomplete classification information. Our result shows the output of the Internal Attacker evaluation.
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VITAE - Smart integration of cloud computing and MCMC based secured WSN to monitor environment
Vitae-revista De La Facultad De Quimica Farmaceutica, 2014Co-Authors: Muhammad R. Ahmed, Xu HuangAbstract:Wireless Sensor Network (WSN) is a low cost and multifunctional emerging technology. Its application ranges from military, health sector, environmental monitoring and industrial application. The maximum benefit of recent technology development can be achieved by integration internet (Cloud Computing) and secured real time data collection platform (secured-WSNs). In order to ensure its functionality especially in malicious environments, security mechanisms are essential in WSNs. Malicious or Internal Attacker has gained prominence and poses the most challenging Attacks to WSN. So, for complete security Internal Attacks need to be handled. In this paper we proposed content-based publish/subscribe (pub/sub) broker model on the Cloud that integrates WSNs to Cloud efficiently and effectively. To secure WSNs we have proposed a new approach for detecting Internal Attack by using Mrakov Chain Monte Carlo (MCMC). It is an efficient real time algorithm. It is good for sensor network as it operates with no or incomplete classification information. Our result shows the output of the Internal Attacker evaluation.
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Novel Protection from Internal Attacks in Wireless Sensor Networks
Lecture Notes in Electrical Engineering, 2013Co-Authors: Xu Huang, Muhammad R. Ahmed, Dharmendra SharmaAbstract:Due to wireless sensor networks are easy and rapid deployed, low cost, low power, self-organized, cooperatively collect the environmental information and realize the integration of the physical world and communication network, they become part of our daily life. However, security threats to WSNs become increasingly diversified and preventions are getting harder and harder due to the open nature of the wireless medium. For example, an adversary can easily eavesdrop and replay or inject fabricated messages. Different cryptographic methods are very limited. This is because of Internal Attack, such as node compromise, becomes another major problem that is different from traditional WSN security problem as it allows an adversary to enter inside the security perimeter of the network. This situation raised a serious challenge for the security of WSNs. In this paper we are investigating Internal Attacks of wireless sensor networks, with an example of multi-hop and a single sinker, by which we present our novel algorithm with controllable robust protecting from Internal Attacks of a wireless sensor network. The final experimental works showed that the proposed algorithm does work well at the designed level.
Yasser Gowayed - One of the best experts on this subject based on the ideXlab platform.
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tensile creep and fatigue of sylramic ibn melt infiltrated sic matrix composites retained properties damage development and failure mechanisms
Composites Science and Technology, 2008Co-Authors: Gregory N. Morscher, Jalees Ahmad, Unni Santhosh, Robert Miller, Greg Ojard, Yasser Gowayed, Reji JohnAbstract:Abstract An understanding of the elevated temperature tensile creep, fatigue, rupture, and retained properties of ceramic matrix composites (CMC) envisioned for use in gas turbine engine applications is essential for component design and life-prediction. In order to quantify the effect of stress, time, temperature, and oxidation for a state-of-the-art composite system, a wide variety of tensile creep, dwell fatigue, and cyclic fatigue experiments were performed in air at 1204 °C for the SiC/SiC CMC system consisting of Sylramic-iBN SiC fibers, BN fiber interphase coating, and slurry-cast melt-infiltrated (MI) SiC-based matrix. Tests were either taken to failure or interrupted. Interrupted tests were then mechanically tested at room temperature to determine the residual properties. The retained properties of most of the composites subjected to tensile creep or fatigue were usually within 20% of the as-produced strength and 10% of the as-produced elastic modulus. It was observed that during creep, residual stresses in the composite are altered to some extent which results in an increased compressive stress in the matrix upon cooling and a subsequent increased stress required to form matrix cracks. Microscopy of polished sections and the fracture surfaces of specimens which failed during stressed-oxidation or after the room-temperature retained property test was performed on some of the specimens in order to quantify the nature and extent of damage accumulation that occurred during the test. It was discovered that the distribution of stress-dependent matrix cracking at 1204 °C was similar to the as-produced composites at room temperature; however, matrix crack growth occurred over time and typically did not appear to propagate through-the-thickness except at the final failure crack. Failure of the composites was due to either oxidation-induced unbridged crack growth, which dominated the higher stress regime (⩾179 MPa) or controlled by degradation of the fibers, probably caused by intrinsic creep-induced flaw growth of the fibers or Internal Attack of the fibers via Si diffusion through the CVI SiC and/or microcracks at the lower stress regime (⩽165 MPa).
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Tensile creep and fatigue of Sylramic-iBN melt-infiltrated SiC matrix composites: Retained properties, damage development, and failure mechanisms
Composites Science and Technology, 2008Co-Authors: Gregory N. Morscher, Jalees Ahmad, Unni Santhosh, Robert Miller, Greg Ojard, Yasser Gowayed, Reji JohnAbstract:An understanding of the elevated temperature tensile creep, fatigue, rupture, and retained properties of ceramic matrix composites (CMC) envisioned for use in gas turbine engine applications is essential for component design and life-prediction. In order to quantify the effect of stress, time, temperature, and oxidation for a state-of-the-art composite system, a wide variety of tensile creep, dwell fatigue, and cyclic fatigue experiments were performed in air at 1204 °C for the SiC/SiC CMC system consisting of Sylramic-iBN SiC fibers, BN fiber interphase coating, and slurry-cast melt-infiltrated (MI) SiC-based matrix. Tests were either taken to failure or interrupted. Interrupted tests were then mechanically tested at room temperature to determine the residual properties. The retained properties of most of the composites subjected to tensile creep or fatigue were usually within 20% of the as-produced strength and 10% of the as-produced elastic modulus. It was observed that during creep, residual stresses in the composite are altered to some extent which results in an increased compressive stress in the matrix upon cooling and a subsequent increased stress required to form matrix cracks. Microscopy of polished sections and the fracture surfaces of specimens which failed during stressed-oxidation or after the room-temperature retained property test was performed on some of the specimens in order to quantify the nature and extent of damage accumulation that occurred during the test. It was discovered that the distribution of stress-dependent matrix cracking at 1204 °C was similar to the as-produced composites at room temperature; however, matrix crack growth occurred over time and typically did not appear to propagate through-the-thickness except at the final failure crack. Failure of the composites was due to either oxidation-induced unbridged crack growth, which dominated the higher stress regime (≥179 MPa) or controlled by degradation of the fibers, probably caused by intrinsic creep-induced flaw growth of the fibers or Internal Attack of the fibers via Si diffusion through the CVI SiC and/or microcracks at the lower stress regime (≤165 MPa). © 2008 Elsevier Ltd.
Jalees Ahmad - One of the best experts on this subject based on the ideXlab platform.
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tensile creep and fatigue of sylramic ibn melt infiltrated sic matrix composites retained properties damage development and failure mechanisms
Composites Science and Technology, 2008Co-Authors: Gregory N. Morscher, Jalees Ahmad, Unni Santhosh, Robert Miller, Greg Ojard, Yasser Gowayed, Reji JohnAbstract:Abstract An understanding of the elevated temperature tensile creep, fatigue, rupture, and retained properties of ceramic matrix composites (CMC) envisioned for use in gas turbine engine applications is essential for component design and life-prediction. In order to quantify the effect of stress, time, temperature, and oxidation for a state-of-the-art composite system, a wide variety of tensile creep, dwell fatigue, and cyclic fatigue experiments were performed in air at 1204 °C for the SiC/SiC CMC system consisting of Sylramic-iBN SiC fibers, BN fiber interphase coating, and slurry-cast melt-infiltrated (MI) SiC-based matrix. Tests were either taken to failure or interrupted. Interrupted tests were then mechanically tested at room temperature to determine the residual properties. The retained properties of most of the composites subjected to tensile creep or fatigue were usually within 20% of the as-produced strength and 10% of the as-produced elastic modulus. It was observed that during creep, residual stresses in the composite are altered to some extent which results in an increased compressive stress in the matrix upon cooling and a subsequent increased stress required to form matrix cracks. Microscopy of polished sections and the fracture surfaces of specimens which failed during stressed-oxidation or after the room-temperature retained property test was performed on some of the specimens in order to quantify the nature and extent of damage accumulation that occurred during the test. It was discovered that the distribution of stress-dependent matrix cracking at 1204 °C was similar to the as-produced composites at room temperature; however, matrix crack growth occurred over time and typically did not appear to propagate through-the-thickness except at the final failure crack. Failure of the composites was due to either oxidation-induced unbridged crack growth, which dominated the higher stress regime (⩾179 MPa) or controlled by degradation of the fibers, probably caused by intrinsic creep-induced flaw growth of the fibers or Internal Attack of the fibers via Si diffusion through the CVI SiC and/or microcracks at the lower stress regime (⩽165 MPa).
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Tensile creep and fatigue of Sylramic-iBN melt-infiltrated SiC matrix composites: Retained properties, damage development, and failure mechanisms
Composites Science and Technology, 2008Co-Authors: Gregory N. Morscher, Jalees Ahmad, Unni Santhosh, Robert Miller, Greg Ojard, Yasser Gowayed, Reji JohnAbstract:An understanding of the elevated temperature tensile creep, fatigue, rupture, and retained properties of ceramic matrix composites (CMC) envisioned for use in gas turbine engine applications is essential for component design and life-prediction. In order to quantify the effect of stress, time, temperature, and oxidation for a state-of-the-art composite system, a wide variety of tensile creep, dwell fatigue, and cyclic fatigue experiments were performed in air at 1204 °C for the SiC/SiC CMC system consisting of Sylramic-iBN SiC fibers, BN fiber interphase coating, and slurry-cast melt-infiltrated (MI) SiC-based matrix. Tests were either taken to failure or interrupted. Interrupted tests were then mechanically tested at room temperature to determine the residual properties. The retained properties of most of the composites subjected to tensile creep or fatigue were usually within 20% of the as-produced strength and 10% of the as-produced elastic modulus. It was observed that during creep, residual stresses in the composite are altered to some extent which results in an increased compressive stress in the matrix upon cooling and a subsequent increased stress required to form matrix cracks. Microscopy of polished sections and the fracture surfaces of specimens which failed during stressed-oxidation or after the room-temperature retained property test was performed on some of the specimens in order to quantify the nature and extent of damage accumulation that occurred during the test. It was discovered that the distribution of stress-dependent matrix cracking at 1204 °C was similar to the as-produced composites at room temperature; however, matrix crack growth occurred over time and typically did not appear to propagate through-the-thickness except at the final failure crack. Failure of the composites was due to either oxidation-induced unbridged crack growth, which dominated the higher stress regime (≥179 MPa) or controlled by degradation of the fibers, probably caused by intrinsic creep-induced flaw growth of the fibers or Internal Attack of the fibers via Si diffusion through the CVI SiC and/or microcracks at the lower stress regime (≤165 MPa). © 2008 Elsevier Ltd.