The Experts below are selected from a list of 270 Experts worldwide ranked by ideXlab platform
Nripati Ranjan Bose - One of the best experts on this subject based on the ideXlab platform.
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Fracture characteristics of vinylester resin under Impact Fatigue
Journal of Applied Polymer Science, 2002Co-Authors: B K Sarkar, Nripati Ranjan BoseAbstract:The Impact Fatigue behavior of a vinylester resin was studied with a pendulum-type repeated-Impact tester especially designed and fabricated for the determination of single-Impact and repeated-Impact strengths. A well-defined energy–endurance Impact Fatigue curve was obtained with a progressive endurance at values of the Impact energy below the critical value, with the endurance limit set at an energy level of 31 N mm, 17.4% of the single-Impact energy. The nature of the crack propagation was investigated for a single Impact as well as high, medium, and low Impact energy levels with progressively longer endurance. The fracture characteristics varied with the Impact energy imparted and the number of cycles endured. The rate of lip growth was high at the higher Impact energy levels with a lower number of endurance cycles and low at the lower Impact energy levels with longer endurance; the repeated Impacts created large and small compressive zones through the bending of specimens with the development of long and short lips, respectively. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1995–2001, 2002
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Impact Fatigue behaviour of vinylester resin matrix composites reinforced with alkali treated jute fibres
Composites Part A-applied Science and Manufacturing, 2002Co-Authors: B K Sarkar, Nripati Ranjan BoseAbstract:Abstract An Impact Fatigue study has been made for the first time on 35% jute/vinylester composites containing both untreated and alkali treated fibres. Longer alkali treatment removed the hemicellulose and improved the crystallinity and gave better fibre dispersion. The flexural strength properties of the composites made from treated fibre were superior. 4 h alkali treated jute fibres gave the optimum combination of improved interfacial bonding and fibre strength properties. However this was not reflected in their Impact Fatigue behaviour. On the contrary, the composites reinforced with 8 h alkali treated fibres displayed superior Impact Fatigue properties. Here, the fibres suffered catastrophic fracture with microfibrillar pull-out at some places and improved the Fatigue resistance property of the composites as evident from SEM micrographs.
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Impact Fatigue of glass fibre: vinylester resin composites
Composites Part A-applied Science and Manufacturing, 2001Co-Authors: Bimal Kumar Sarkar, Nripati Ranjan BoseAbstract:Abstract An Impact Fatigue study has been made for the first time on 63.5% glass fibre reinforced vinylester resin, notched composites. The study was conducted using a pendulum type repeated Impact apparatus specially designed and fabricated for determining single and repeated Impact strengths. Well-defined Impact Fatigue ( S – N ) behaviour, having a progressive endurance below the threshold single cycle Impact fracture strength, with a limit, has been demonstrated. Fractographic analysis revealed fracture by primary debonding, with fibre breakage and pull-out in the tensile zone, but a shear fracture of fibre bundles in the compressive zone of the specimen. Residual strength measured after Impact Fatigued showed retention of the property at high Impact energy levels, up to about 10 2 Impact cycles, thereafter a gradual drop to about 10 3 Impact cycles followed by a rapid drop. The residual modulus and toughness showed a gradual drop with the increasing number of Impacts endured. It is suggested that a few large cracks and an increased volume of microcracks in the matrix, with damaged fibres at high and low Impact endurances, respectively, account for the failures of the composites under Impact Fatigue.
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Behaviour of E-glass fibre reinforced vinylester resin composites under Impact Fatigue
Bulletin of Materials Science, 2001Co-Authors: B K Sarkar, Nripati Ranjan BoseAbstract:An Impact Fatigue study has been made for the first time on 63.5% glass fibre reinforced vinylester resin notched composites. The study was conducted in a pendulum type repeated Impact apparatus especially designed and fabricated for determining single and repeated Impact strengths. A well-defined Impact Fatigue (S-N) behaviour, having a progressive endurance below the threshold single cycle Impact fracture stress with decreasing applied stress has been demonstrated. Fractographic analysis revealed fracture by primary debonding having fibre breakage and pullout at the tensile zone, but a shear fracture of fibre bundles at the compressive zone of the specimen. The residual strength, modulus and toughness showed retention of the properties at high Impact stress levels up to 1000 Impacts followed by a sharp drop. Cumulative residual stresses with each number of Impacts not withstanding the static Fatigue failure at long endurances have been ascribed for the composite failures under the repeated Impact stresses.
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Impact Fatigue behaviour of carbon fibre-reinforced vinylester resin composites
Bulletin of Materials Science, 2001Co-Authors: B K Sarkar, A K Rana, Nripati Ranjan BoseAbstract:Two types of unidirectional carbon fibre, one of high strength (DHMS) and another of medium strength (VLMS) reinforced vinylester resin composites have been examined for their Impact Fatigue behaviour over 104 Impact cycles for the first time. The study was conducted using a pendulum type repeated Impact apparatus specially designed and constructed for the purpose. A well-defined Impact Fatigue behaviour (S-N type curve) curve has been demonstrated. It showed a plateau region of 10–102 cycles immediately below the single cycle Impact strength, followed by progressive endurance with decreasing Impact loads, culminating in an endurance limit at about 71% and 85% of the single Impact strength for DHMS-48 and VLMS-48, respectively. Analysis of the fractured surfaces revealed primary debonding, fibre breakage and pull-out at the tensile zone of the samples and a shear mode of fracture with breakage of fibre bundles at the compressive zone of the samples. The occurrence of a few major macrocracks in the matrix with fibre breakage at the high load-low endurance region and development of multiple microcracks in the matrix, coalescing and fibre breakage at the low-load-high endurance region have been inferred to explain the Fatigue behaviour of the composites examined.
B K Sarkar - One of the best experts on this subject based on the ideXlab platform.
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Fracture characteristics of vinylester resin under Impact Fatigue
Journal of Applied Polymer Science, 2002Co-Authors: B K Sarkar, Nripati Ranjan BoseAbstract:The Impact Fatigue behavior of a vinylester resin was studied with a pendulum-type repeated-Impact tester especially designed and fabricated for the determination of single-Impact and repeated-Impact strengths. A well-defined energy–endurance Impact Fatigue curve was obtained with a progressive endurance at values of the Impact energy below the critical value, with the endurance limit set at an energy level of 31 N mm, 17.4% of the single-Impact energy. The nature of the crack propagation was investigated for a single Impact as well as high, medium, and low Impact energy levels with progressively longer endurance. The fracture characteristics varied with the Impact energy imparted and the number of cycles endured. The rate of lip growth was high at the higher Impact energy levels with a lower number of endurance cycles and low at the lower Impact energy levels with longer endurance; the repeated Impacts created large and small compressive zones through the bending of specimens with the development of long and short lips, respectively. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1995–2001, 2002
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Impact Fatigue behaviour of vinylester resin matrix composites reinforced with alkali treated jute fibres
Composites Part A-applied Science and Manufacturing, 2002Co-Authors: B K Sarkar, Nripati Ranjan BoseAbstract:Abstract An Impact Fatigue study has been made for the first time on 35% jute/vinylester composites containing both untreated and alkali treated fibres. Longer alkali treatment removed the hemicellulose and improved the crystallinity and gave better fibre dispersion. The flexural strength properties of the composites made from treated fibre were superior. 4 h alkali treated jute fibres gave the optimum combination of improved interfacial bonding and fibre strength properties. However this was not reflected in their Impact Fatigue behaviour. On the contrary, the composites reinforced with 8 h alkali treated fibres displayed superior Impact Fatigue properties. Here, the fibres suffered catastrophic fracture with microfibrillar pull-out at some places and improved the Fatigue resistance property of the composites as evident from SEM micrographs.
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Behaviour of E-glass fibre reinforced vinylester resin composites under Impact Fatigue
Bulletin of Materials Science, 2001Co-Authors: B K Sarkar, Nripati Ranjan BoseAbstract:An Impact Fatigue study has been made for the first time on 63.5% glass fibre reinforced vinylester resin notched composites. The study was conducted in a pendulum type repeated Impact apparatus especially designed and fabricated for determining single and repeated Impact strengths. A well-defined Impact Fatigue (S-N) behaviour, having a progressive endurance below the threshold single cycle Impact fracture stress with decreasing applied stress has been demonstrated. Fractographic analysis revealed fracture by primary debonding having fibre breakage and pullout at the tensile zone, but a shear fracture of fibre bundles at the compressive zone of the specimen. The residual strength, modulus and toughness showed retention of the properties at high Impact stress levels up to 1000 Impacts followed by a sharp drop. Cumulative residual stresses with each number of Impacts not withstanding the static Fatigue failure at long endurances have been ascribed for the composite failures under the repeated Impact stresses.
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Impact Fatigue behaviour of carbon fibre-reinforced vinylester resin composites
Bulletin of Materials Science, 2001Co-Authors: B K Sarkar, A K Rana, Nripati Ranjan BoseAbstract:Two types of unidirectional carbon fibre, one of high strength (DHMS) and another of medium strength (VLMS) reinforced vinylester resin composites have been examined for their Impact Fatigue behaviour over 104 Impact cycles for the first time. The study was conducted using a pendulum type repeated Impact apparatus specially designed and constructed for the purpose. A well-defined Impact Fatigue behaviour (S-N type curve) curve has been demonstrated. It showed a plateau region of 10–102 cycles immediately below the single cycle Impact strength, followed by progressive endurance with decreasing Impact loads, culminating in an endurance limit at about 71% and 85% of the single Impact strength for DHMS-48 and VLMS-48, respectively. Analysis of the fractured surfaces revealed primary debonding, fibre breakage and pull-out at the tensile zone of the samples and a shear mode of fracture with breakage of fibre bundles at the compressive zone of the samples. The occurrence of a few major macrocracks in the matrix with fibre breakage at the high load-low endurance region and development of multiple microcracks in the matrix, coalescing and fibre breakage at the low-load-high endurance region have been inferred to explain the Fatigue behaviour of the composites examined.
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Impact Fatigue of a porcelain ceramic
International Journal of Fatigue, 1995Co-Authors: Soumen Maity, B K SarkarAbstract:An improved type of Impact Fatigue testing apparatus has been designed to determine the repeated Impact Fatigue of ceramic materials. A hard porcelain tested showed a definite Fatigue behaviour with increasing endurance at decreasing Impact energy levels. The effect of cumulative residual stress is suggested to explain the Fatigue behaviour.
Vadim V Silberschmidt - One of the best experts on this subject based on the ideXlab platform.
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Impact Fatigue of Adhesive Joints
Key Engineering Materials, 2020Co-Authors: Vadim V Silberschmidt, J.p. Casas-rodriguez, I A AshcroftAbstract:The paper presents results of studies into the effect of repetitive low-energy Impacting (known as Impact Fatigue) on reliability and crack growth in adhesively bonded joints. This type of loading is compared to the standard tensile Fatigue in order to assess severity of such loading regime. Another loading type studied is a combination of a small portion of repetitive Impacts with tensile Fatigue. Crack propagation in a joint exposed to these types of loading is studied experimentally and numerically (with finite elements). This analysis is accompanied by microstructural studies of various damage processes, active at different stages of the crack growth process.
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Damage Analysis of CFRP under Impact Fatigue
Shock and Vibration, 2020Co-Authors: George Tsigkourakos, Vadim V Silberschmidt, I A AshcroftAbstract:In recent years carbon fibre reinforced polymers (CFRPs) have become some of the most important structural materials in the aerospace industry due to their excellent stiffness and strength to weight ratios. The real-life loading histories of aerospace composite components and structures involve the generation of transient loads that can propagate as cyclic Impacts. This phenomenon is known as Impact Fatigue (IF). Such loads can cause various types of damage in composites, including fibre breakage, transverse matrix cracking, de-bonding between fibres and matrix and delamination, resulting in a reduction of residual stiffness and a loss of functionality.
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Analysis of Damage Propagation in Single Lap Joints in Impact Fatigue
Vibro-Impact Dynamics of Ocean Systems and Related Problems, 2020Co-Authors: George Tsigkourakos, J.p. Casas-rodriguez, Vadim V SilberschmidtAbstract:Repetitive low-velocity Impact loading can result in substantial damage in adhesively bonded joints after few Impacts with low force levels compared to other types of loading. The main aim of this paper is to investigate the behavior of adhesive joints subjected to Impact Fatigue (IF) and standard Fatigue (SF) as well as their combinations and compare their effect on damage in single lap joints (SLJs). Damage evolution in both SF and IF regimes is analyzed in terms of the deterioration of residual strength of joints after respective loading histories. Fractography analysis is implemented to correlate the residual stiffness reduction under IF and SF loading with the crack propagation behavior of SLJs.
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Impact Fatigue in adhesive joints
Proceedings of the Institution of Mechanical Engineers Part C: Journal of Mechanical Engineering Science, 2008Co-Authors: Vadim V Silberschmidt, J.p. Casas-rodriguez, I A AshcroftAbstract:One of the forms of a vibro-Impact effect in engineering components is Impact Fatigue (IF) caused by a cyclic repetition of low energy, low-velocity Impacts, for instance, in aerospace structures. It can have a highly detrimental Impact on performance and reliability of such components, exacerbated by the fact that in many cases it is disguised in loading histories by non-Impact loading cycles with higher amplitudes. Since the latter are traditionally considered as most dangerous in standard Fatigue, IF has not yet received deserved attention; it is less studied and practically unknown to specialists in structural integrity. Though there is a broad understanding of the danger of high-energy single Impacts, repetitive Impacting of components has been predominantly studied for very short series. This paper aims at the analysis of IF of adhesively bonded joints, which are becoming more broadly used in aerospace applications. The study is implemented for two types of typical adherends — an aluminium alloy and...
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damage in adhesively bonded cfrp joints sinusoidal and Impact Fatigue
Composites Science and Technology, 2008Co-Authors: J P Casasrodriguez, I A Ashcroft, Vadim V SilberschmidtAbstract:The main aim of this paper is to investigate the behaviour of adhesively bonded CFRP joints subjected to cyclic low-velocity Impacts and to compare this with fracture in specimens tested in standard Fatigue (i.e. non-Impacting, constant amplitude, sinusoidal Fatigue). It is seen that the accumulated energy associated with damage in Impact-Fatigue is significantly lower than that associated with similar damage in standard Fatigue and that the mechanisms of failure are very different for the two loading regimes. For both types of loading, fracture initiates in the adhesive layer and then propagates into the 0° ply of the composite adjacent to the adhesive layer. However, the fracture surfaces after Impact-Fatigue are generally less uniform and exhibit more signs of high rate/brittle fracture than seen in the fracture surfaces after standard Fatigue testing. Various parameters are proposed to characterise damage in standard and Impact-Fatigue and it is shown that crack velocity, accumulated absorbed energy and normalised maximum force are all useful parameters for characterising damage evolution.
Serkan Kara - One of the best experts on this subject based on the ideXlab platform.
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An investigation on the Impact Fatigue characteristics of valve leaves for small hermetic reciprocating compressors in a new automated test system
Fatigue & Fracture of Engineering Materials & Structures, 2012Co-Authors: A. Can Altunlu, Ismail Lazoglu, Emre Oguz, Serkan KaraAbstract:This paper presents an investigation on the Impact Fatigue characteristics of valve leaves that are prevalently used in hermetic reciprocating compressors especially for the household type refrigerators. A unique automated Impact Fatigue test system has been designed and produced, which enables to carry out Impact Fatigue tests of the compressor valve leaves under the desired Impact velocities. The test system serves investigations on the Impact Fatigue characteristics with the ability of crack detection and as the subsequent step of automatically terminating the test. The crack detection technique incorporates a non-contact actuation, a data acquisition system and a microphone. The investigation relates the Impact Fatigue lifetime of the valve leaves with the Impact velocity, asymmetrical Impact, operation temperature, material type (carbon strip steel, stainless strip steel and new stainless strip steel grade) and tumbling operation duration. Microscopic and metallographic observations were performed on the specimens. It was observed that the crack initiated at the edge of the valve leaves on the contact surface of valve leaf and vale plate and a particle is torn away from the edge before propagation. As the crack propagates, branching along the crack path is caused by the geometrical shape and stress waves on the valve leaves. The investigation and introduced test system guide the design optimization of valve leaves in terms of compressor performance due to energy consumption and lifetime of the valve leaf.
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Impact Fatigue Characteristics of Valve Leaves for Small Hermetic Reciprocating Compressors
2010Co-Authors: A. Can Altunlu, Ismail Lazoglu, Emre Oguz, Serkan KaraAbstract:This paper presents an investigation on the Impact Fatigue characteristics of valve leaves that are prevalently used in hermetic reciprocating compressors especially for the household type refrigerators. The investigation relates the Impact Fatigue lifetime of the valve leaves that is the heart of the compressor, with the working temperature, material type (carbon steel, stainless steel and improved stainless steel grade) and tumbling duration after the manufacturing process. The investigation provides a better understanding of the Impact Fatigue characteristics of valve leaves while designing a high performance compressor to decrease the energy consumption. A unique automated Impact Fatigue test system was designed and produced, which enables to carry out Impact Fatigue tests of the compressor valve leaves under the desired Impact velocities. In the test system, original valve plate and valve leaf couple was utilized through the experimentation in order to simulate the real behavior in the compressor. A fixture was designed to mount the valve plate. The main principle of the system is to create pulsating airflow through a high frequency solenoid valve. The Impact Fatigue life was determined for various Impact velocities and at different operating temperatures.
Li He - One of the best experts on this subject based on the ideXlab platform.
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Impact Fatigue behaviour of gfrp mesh reinforced engineered cementitious composites for runway pavement
Construction and Building Materials, 2020Co-Authors: Chao Wu, Xianfeng Cheng, Victor C Li, Li HeAbstract:Abstract Concrete runway pavement faces a long term issue of cracking resulting in reduced durability and increased maintenance cost. This paper proposes a new type of runway pavement using engineered cementitious composites (ECC) with glass fiber reinforced polymer (GFRP) mesh reinforcements. This paper investigates the Impact Fatigue behaviour of the GFRP mesh reinforced ECC pavement through a series of cyclic Impact tests. Five Impact pressures were adopted considering the Impacts induced by various types of airplanes. The number of Impacts when the first crack appeared (N0) and at the failure (NC) were reported. The experimental results show that N0 of GFRP mesh reinforced ECC is increased by a maximum of 800 times comparing to that of concrete pavement. The GFRP mesh reinforced ECC could sustain 30,000 Impacts without failure. Finally, a non-destructive health monitoring algorithm was proposed based on the ultrasonic testing method and validated using the experimental results. This method is able to assess the damage status, and predict the remaining Impact Fatigue life of the GFRP mesh reinforced ECC pavement.
