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In this paper the tensile properties of jute natural and its hybrid laminate composites are evalu... more In this paper the tensile properties of jute natural and its hybrid laminate composites are evaluated.For hybrid composite Jute fiber laminate is laminated with E-Glass fiber laminate along with epoxy matrix. The laminates are fabricated using hand layup technique with reinforcement and matrix weight fraction ratio of 40:60. The tensile test was performed for composites with and without water. The jute/glass hybrid composite has 1.4 times more ultimate tensile strength than that of jute natural fiber laminate composite. Also, it was observed that the strength of the moisture content of hybrid jute/glass laminate composites will be more than that of jute natural

Sādhanā, 2020

In this paper, the total energy release rates for unidirectional glass/epoxy composites were eval... more In this paper, the total energy release rates for unidirectional glass/epoxy composites were evaluated using Compact Tension Shear (CTS) and Four-Point Bend (FPB) Mixed mode (I/II) fracture specimens. Unidirectional glass fibre laminates were considered for the experimental work. Specimen plates of required thickness were fabricated using hand lay-up technique. The experimental study was conducted for seven loading angles varying from 0°to 90°with an increment of 15°for CTS specimen and 6 crack positions varying from 0 to 1 with an increment of 0.2 for FPB specimen. Load vs. displacement data are plotted to evaluate the peak loads for both the CTS and FPB Mixed mode (I/II) fracture specimens of various loading angles and crack positions, which are utilized to estimate the total energy release rate. It is found that the total energy release rate depends on the loading angle and crack positions for CTS and FPB Mixed mode (I/II) fracture specimens. For a particular load, the total energy release rate is highly dominating in FPB compared with the CTS fracture specimen. Hence, the FPB Mixed mode (I/II) fracture specimen can be preferred over CTS Mixed mode (I/II) fracture specimen to evaluate the total energy release rate. Keywords. Total energy release rate; compact tension shear specimen (CTS); four-point bend specimen (FPB); unidirectional glass/epoxy laminate.

Lecture Notes in Mechanical Engineering, 2020

On the relationship between stress intensity factor (K) and minimum plastic zone radius (MPZR) fo... more On the relationship between stress intensity factor (K) and minimum plastic zone radius (MPZR) for four point bend specimen under mixed mode loading

Frattura ed Integrità Strutturale, 2020

To study glass/epoxy fiber orientation effects on translaminar fracture toughness under Mixed mod... more To study glass/epoxy fiber orientation effects on translaminar fracture toughness under Mixed mode(I/II) load using asymmetric Four Point Bend specimen. Fracture toughness values for different fiber-oriented glass/epoxy laminates under Mixed modes are compared with unidirectional glass/epoxy laminates. Specimens were fabricated using hand layup technique with (0/45)° and (0/90)° fiber oriented glass fiber. The experimental study was conducted for 6 crack positions varying from s/d=0(Mode-II) to 1(Mode-1) with an increment of 0.2 for Four Point Bend specimen. The specimens were tested under universal testing machine to obtain peak loads and further evaluate fracture toughness. The experimental test results show fracture toughness can be increased by orienting the fiber in the laminate. Fracture toughness is highly dominating for (0/90)° fiber-oriented laminates compared to 0° and (0/45)° glass/epoxy laminates.

Frattura ed Integrità Strutturale, 2016

The paper describes test specimen thickness effect on stress intensity factor (KI), and T-stresse... more The paper describes test specimen thickness effect on stress intensity factor (KI), and T-stresses stresses (T11 and T33) for a Compact Tension specimen. Formulations to estimate 3D K I , T 11 and T 33 stresses are proposed based on extensive 3D Finite element analyses. These formulations help to estimate magnitudes of 3D K I and T 11 and T 33 which are helpful to quantify in-plane and out-of-plane constraint effect of the crack tip. The proposed formulations are validated with the similar results available in literature and found to be within acceptable error.

Frattura ed Integrità Strutturale, 2014

In this investigation, three-dimensional elastic finite element analyses have been conducted to c... more In this investigation, three-dimensional elastic finite element analyses have been conducted to compute the stress intensity factor (KI) in a SENB specimen with varied thickness (B) and crack-length to width ratio (a/W). The results indicate that the magnitude of KI depends on B, and significantly varies along the crackfront from surface to the center of the specimen. The maximum value of KI is found at mid plane of the specimen. Based on the present 3D finite element calculations an effort is made to propose the new analytical relationship between maximum KI and specimen a/W, which helps to estimate maximum KI by only knowing specimen geometry and applied load.

Journal of Materials Processing Technology, 2007

International Journal of Engineering, Science and Technology, 2011

Lecture Notes in Mechanical Engineering, 2020

Aircraft wings are slender because of their high aspect ratios resulting from large spans and the... more Aircraft wings are slender because of their high aspect ratios resulting from large spans and they are susceptible to vibration problems. Hence, in the design of aircraft wings, frequency analysis is a very important input. In this work dynamic behavior of Boeing 747-400 (having aerofoil number BAC 465) aircraft wing is carried out using finite element analysis. A CAD model of the wing is prepared including aerofoil, the engine attached to the wing and the details of the winglet. Detailed frequency analysis in the range 0–300 Hz of the wing with respect to maximum displacement and von Mises stress is conducted. The results obtained are useful inputs for analyzing resonant frequencies and the design of the wing.

The studies on crack-tip plastic zones are of fundamental importance in describing the process of... more The studies on crack-tip plastic zones are of fundamental importance in describing the process of failure and in formulating various fracture criteria. The material fracture by opening mode (mode I) is not lonely responsible for fracture propagation. Many industrial examples show the presence of mode II and mixed mode I + II loading in machine/structural components. In the present study, an emphasis is laid to study the size and shape of the plastic zone at the crack tip under mode I, mode II and mixed mode I + II loading conditions. The shape and size of crack-tip plastic zones have been estimated in a Compact tensile shear (CTS) specimen under mixed mode loading according to von Mises yield criteria. The results obtained are analyzed with reference to loading angle and effective stress intensity factor.

The studies on crack-tip plastic zones are of fundamental importance in describing the process of... more The studies on crack-tip plastic zones are of fundamental importance in describing the process of failure and in formulating various fracture criteria. The study of out-of-plane constraint in fracture analysis is important and needs a detailed 3 dimensional analysis of crack-tip plastic zone. This paper presents 3 dimensional finite element analyses of crack-tip plastic zones and effect of specimen thickness on crack-tip plastic zone shape and size considering a CT specimen with crack length to width ratio (a/W) equal to 0.5. The results indicate that the shape of plastic zone does not correspond to classical “dog-bone” shape. The analysis also indicates that the shape of plane stress plastic zone on the specimen surface as expected in classical model is not reproduced. The maximum plastic zone size is found to occur at the centre of the specimen, in contrary to conventional shape, indicating a significant change in the shape of plastic zone. The results are used to discuss the out-...

In this investigation the relationship between J-integral and CTOD is studied considering a Compa... more In this investigation the relationship between J-integral and CTOD is studied considering a Compact Tensile (CT) specimen using 3 dimensional finite element analyses. The magnitude of CTOD is estimated by 90-intercept method on the surface and at the centre of the specimen, and also by plastic hinge model. The results indicate that the magnitudes of CTOD estimated by 90intercept method at the centre of the specimen are found to be higher than that on the surface. The results reveal an inconsistency in estimation of CTOD by 90-intercept method and by plastic hinge model. The CTOD values obtained by both the methods are found to be linearly proportional to Jintegral. The linear proportionality constant dn between CTOD and J is found to be strongly depend on the method of estimation of CTOD and specimen thickness. Introduction Elastic plastic fracture mechanics (EPFM) is the domain of fracture analysis, which considers extensive plastic deformation ahead of crack-tips prior to fracture...

Materials Today: Proceedings

In the past few decades, vegetable fibers became the viable alternative to petroleum-based fibers... more In the past few decades, vegetable fibers became the viable alternative to petroleum-based fibers in composite industry, due to their renewability, biodegradability and eco-friendly properties. In the present work, a new leaf fiber extracted from Furcraea Foetida Mediopicto (ffm) plant, has been characterized and reported. Morphological, physical, mechanical and thermal properties of ffm fiber were examined by performing comprehensive characterization. Findings revealed that ffm fibers have an average low density and better mechanical properties compared to other fibers. Micro structural examination revealed the cross-section of the ffm fiber is the honeycomb structure. XRD analysis indicated the 49.7% crystalline content of ffm fiber. TG and DTA analysis revealed that ffm fibers are thermally stable up to 360 ℃. Present investigation, indicates that ffm fibers are highly suitable as reinforcement agents in polymeric matrices for various light weight-medium load-thermal insulation a...

The crack-tip plastic zones are of vital consequence in connecting fracture initiation for inclin... more The crack-tip plastic zones are of vital consequence in connecting fracture initiation for inclined cracks. Minimum plastic zone radius (MPZR) criterion is a new postulation illustrated for the fracture initiation (θ o ) for inclined cracks. In this paper, a detailed study of the size, shape and fracture initiation of the crack-tip plastic zone (PZ) were made for various inclined cracks (β) of mixed mode (I/II) fracture specimen. The elastic numerical analysis were carried for Single Edge Notch Tension (SENT) mixed mode(I/II) fracture specimen of various β and crack to width (a/W) ratios=0.1-0.7. Based on von Mises yield criterion the size, shape and θ o of crack-tip plastic zones have been estimated in a SENT mixed mode (I/II) fracture specimen for various β and a/W ratios. The numerical estimated fracture initiations are compared with those of the theoretical fracture criteria such as; the maximum tensile stress criterion (MTS) and the minimum strain energy density criterion (MSED...

In this investigation, three-dimensional elastic finite element analyses have been conducted to c... more In this investigation, three-dimensional elastic finite element analyses have been conducted to compute the stress intensity factor (K I) in a SENB specimen with varied thickness (B) and crack-length to width ratio (a/W). The results indicate that the magnitude of K I depends on B, and significantly varies along the crackfront from surface to the center of the specimen. The maximum value of K I is found at mid plane of the specimen. Based on the present 3D finite element calculations an effort is made to propose the new analytical relationship between maximum K I and specimen a/W, which helps to estimate maximum K I by only knowing specimen geometry and applied load.

International Journal of Engineering, Science and Technology, Sep 28, 2010

Studies on crack-tip plastic zones are of fundamental importance in describing the process of fai... more Studies on crack-tip plastic zones are of fundamental importance in describing the process of failure and in formulating various fracture criteria. Minimum plastic zone radius (MPZR) theory is widely used in prediction of crack initiation angle in mixed mode fracture analysis of engineering materials. In this study, shape and size of mixed mode (I/II) crack-tip plastic zones have been estimated by finite element analysis in a four point bend specimen according to von Mises yield criteria. The results obtained are used to analyze the MPZR criterion with respect to the effective stress intensity factor (K eff) and elastic mode mixity (M e).

Fatigue of Aircraft Structures

The effect of an anticorrosive layer on the fatigue life of 2024-T-351-aluminium alloy has been s... more The effect of an anticorrosive layer on the fatigue life of 2024-T-351-aluminium alloy has been studied in the present investigation. The fatigue tests were conducted on the aluminium alloy with and without anodizing to evaluate the fatigue life. The results indicate that the fatigue life of the anodized specimens is significantly shorter than that of untreated specimens. Further, experiments were conducted to evaluate the effect of the anodizing process parameters on the fatigue life of anodized specimens. These results show that the fatigue life of anodized aluminium alloy can be improved by controlling the anodizing process parameters such as process temperature, voltage, and time of immersion.

In this paper the tensile properties of jute natural and its hybrid laminate composites are evalu... more In this paper the tensile properties of jute natural and its hybrid laminate composites are evaluated.For hybrid composite Jute fiber laminate is laminated with E-Glass fiber laminate along with epoxy matrix. The laminates are fabricated using hand layup technique with reinforcement and matrix weight fraction ratio of 40:60. The tensile test was performed for composites with and without water. The jute/glass hybrid composite has 1.4 times more ultimate tensile strength than that of jute natural fiber laminate composite. Also, it was observed that the strength of the moisture content of hybrid jute/glass laminate composites will be more than that of jute natural

Sādhanā, 2020

In this paper, the total energy release rates for unidirectional glass/epoxy composites were eval... more In this paper, the total energy release rates for unidirectional glass/epoxy composites were evaluated using Compact Tension Shear (CTS) and Four-Point Bend (FPB) Mixed mode (I/II) fracture specimens. Unidirectional glass fibre laminates were considered for the experimental work. Specimen plates of required thickness were fabricated using hand lay-up technique. The experimental study was conducted for seven loading angles varying from 0°to 90°with an increment of 15°for CTS specimen and 6 crack positions varying from 0 to 1 with an increment of 0.2 for FPB specimen. Load vs. displacement data are plotted to evaluate the peak loads for both the CTS and FPB Mixed mode (I/II) fracture specimens of various loading angles and crack positions, which are utilized to estimate the total energy release rate. It is found that the total energy release rate depends on the loading angle and crack positions for CTS and FPB Mixed mode (I/II) fracture specimens. For a particular load, the total energy release rate is highly dominating in FPB compared with the CTS fracture specimen. Hence, the FPB Mixed mode (I/II) fracture specimen can be preferred over CTS Mixed mode (I/II) fracture specimen to evaluate the total energy release rate. Keywords. Total energy release rate; compact tension shear specimen (CTS); four-point bend specimen (FPB); unidirectional glass/epoxy laminate.

Lecture Notes in Mechanical Engineering, 2020

On the relationship between stress intensity factor (K) and minimum plastic zone radius (MPZR) fo... more On the relationship between stress intensity factor (K) and minimum plastic zone radius (MPZR) for four point bend specimen under mixed mode loading

Frattura ed Integrità Strutturale, 2020

To study glass/epoxy fiber orientation effects on translaminar fracture toughness under Mixed mod... more To study glass/epoxy fiber orientation effects on translaminar fracture toughness under Mixed mode(I/II) load using asymmetric Four Point Bend specimen. Fracture toughness values for different fiber-oriented glass/epoxy laminates under Mixed modes are compared with unidirectional glass/epoxy laminates. Specimens were fabricated using hand layup technique with (0/45)° and (0/90)° fiber oriented glass fiber. The experimental study was conducted for 6 crack positions varying from s/d=0(Mode-II) to 1(Mode-1) with an increment of 0.2 for Four Point Bend specimen. The specimens were tested under universal testing machine to obtain peak loads and further evaluate fracture toughness. The experimental test results show fracture toughness can be increased by orienting the fiber in the laminate. Fracture toughness is highly dominating for (0/90)° fiber-oriented laminates compared to 0° and (0/45)° glass/epoxy laminates.

Frattura ed Integrità Strutturale, 2016

The paper describes test specimen thickness effect on stress intensity factor (KI), and T-stresse... more The paper describes test specimen thickness effect on stress intensity factor (KI), and T-stresses stresses (T11 and T33) for a Compact Tension specimen. Formulations to estimate 3D K I , T 11 and T 33 stresses are proposed based on extensive 3D Finite element analyses. These formulations help to estimate magnitudes of 3D K I and T 11 and T 33 which are helpful to quantify in-plane and out-of-plane constraint effect of the crack tip. The proposed formulations are validated with the similar results available in literature and found to be within acceptable error.

Frattura ed Integrità Strutturale, 2014

In this investigation, three-dimensional elastic finite element analyses have been conducted to c... more In this investigation, three-dimensional elastic finite element analyses have been conducted to compute the stress intensity factor (KI) in a SENB specimen with varied thickness (B) and crack-length to width ratio (a/W). The results indicate that the magnitude of KI depends on B, and significantly varies along the crackfront from surface to the center of the specimen. The maximum value of KI is found at mid plane of the specimen. Based on the present 3D finite element calculations an effort is made to propose the new analytical relationship between maximum KI and specimen a/W, which helps to estimate maximum KI by only knowing specimen geometry and applied load.

Journal of Materials Processing Technology, 2007

International Journal of Engineering, Science and Technology, 2011

Lecture Notes in Mechanical Engineering, 2020

Aircraft wings are slender because of their high aspect ratios resulting from large spans and the... more Aircraft wings are slender because of their high aspect ratios resulting from large spans and they are susceptible to vibration problems. Hence, in the design of aircraft wings, frequency analysis is a very important input. In this work dynamic behavior of Boeing 747-400 (having aerofoil number BAC 465) aircraft wing is carried out using finite element analysis. A CAD model of the wing is prepared including aerofoil, the engine attached to the wing and the details of the winglet. Detailed frequency analysis in the range 0–300 Hz of the wing with respect to maximum displacement and von Mises stress is conducted. The results obtained are useful inputs for analyzing resonant frequencies and the design of the wing.

The studies on crack-tip plastic zones are of fundamental importance in describing the process of... more The studies on crack-tip plastic zones are of fundamental importance in describing the process of failure and in formulating various fracture criteria. The material fracture by opening mode (mode I) is not lonely responsible for fracture propagation. Many industrial examples show the presence of mode II and mixed mode I + II loading in machine/structural components. In the present study, an emphasis is laid to study the size and shape of the plastic zone at the crack tip under mode I, mode II and mixed mode I + II loading conditions. The shape and size of crack-tip plastic zones have been estimated in a Compact tensile shear (CTS) specimen under mixed mode loading according to von Mises yield criteria. The results obtained are analyzed with reference to loading angle and effective stress intensity factor.

The studies on crack-tip plastic zones are of fundamental importance in describing the process of... more The studies on crack-tip plastic zones are of fundamental importance in describing the process of failure and in formulating various fracture criteria. The study of out-of-plane constraint in fracture analysis is important and needs a detailed 3 dimensional analysis of crack-tip plastic zone. This paper presents 3 dimensional finite element analyses of crack-tip plastic zones and effect of specimen thickness on crack-tip plastic zone shape and size considering a CT specimen with crack length to width ratio (a/W) equal to 0.5. The results indicate that the shape of plastic zone does not correspond to classical “dog-bone” shape. The analysis also indicates that the shape of plane stress plastic zone on the specimen surface as expected in classical model is not reproduced. The maximum plastic zone size is found to occur at the centre of the specimen, in contrary to conventional shape, indicating a significant change in the shape of plastic zone. The results are used to discuss the out-...

In this investigation the relationship between J-integral and CTOD is studied considering a Compa... more In this investigation the relationship between J-integral and CTOD is studied considering a Compact Tensile (CT) specimen using 3 dimensional finite element analyses. The magnitude of CTOD is estimated by 90-intercept method on the surface and at the centre of the specimen, and also by plastic hinge model. The results indicate that the magnitudes of CTOD estimated by 90intercept method at the centre of the specimen are found to be higher than that on the surface. The results reveal an inconsistency in estimation of CTOD by 90-intercept method and by plastic hinge model. The CTOD values obtained by both the methods are found to be linearly proportional to Jintegral. The linear proportionality constant dn between CTOD and J is found to be strongly depend on the method of estimation of CTOD and specimen thickness. Introduction Elastic plastic fracture mechanics (EPFM) is the domain of fracture analysis, which considers extensive plastic deformation ahead of crack-tips prior to fracture...

Materials Today: Proceedings

In the past few decades, vegetable fibers became the viable alternative to petroleum-based fibers... more In the past few decades, vegetable fibers became the viable alternative to petroleum-based fibers in composite industry, due to their renewability, biodegradability and eco-friendly properties. In the present work, a new leaf fiber extracted from Furcraea Foetida Mediopicto (ffm) plant, has been characterized and reported. Morphological, physical, mechanical and thermal properties of ffm fiber were examined by performing comprehensive characterization. Findings revealed that ffm fibers have an average low density and better mechanical properties compared to other fibers. Micro structural examination revealed the cross-section of the ffm fiber is the honeycomb structure. XRD analysis indicated the 49.7% crystalline content of ffm fiber. TG and DTA analysis revealed that ffm fibers are thermally stable up to 360 ℃. Present investigation, indicates that ffm fibers are highly suitable as reinforcement agents in polymeric matrices for various light weight-medium load-thermal insulation a...

The crack-tip plastic zones are of vital consequence in connecting fracture initiation for inclin... more The crack-tip plastic zones are of vital consequence in connecting fracture initiation for inclined cracks. Minimum plastic zone radius (MPZR) criterion is a new postulation illustrated for the fracture initiation (θ o ) for inclined cracks. In this paper, a detailed study of the size, shape and fracture initiation of the crack-tip plastic zone (PZ) were made for various inclined cracks (β) of mixed mode (I/II) fracture specimen. The elastic numerical analysis were carried for Single Edge Notch Tension (SENT) mixed mode(I/II) fracture specimen of various β and crack to width (a/W) ratios=0.1-0.7. Based on von Mises yield criterion the size, shape and θ o of crack-tip plastic zones have been estimated in a SENT mixed mode (I/II) fracture specimen for various β and a/W ratios. The numerical estimated fracture initiations are compared with those of the theoretical fracture criteria such as; the maximum tensile stress criterion (MTS) and the minimum strain energy density criterion (MSED...

In this investigation, three-dimensional elastic finite element analyses have been conducted to c... more In this investigation, three-dimensional elastic finite element analyses have been conducted to compute the stress intensity factor (K I) in a SENB specimen with varied thickness (B) and crack-length to width ratio (a/W). The results indicate that the magnitude of K I depends on B, and significantly varies along the crackfront from surface to the center of the specimen. The maximum value of K I is found at mid plane of the specimen. Based on the present 3D finite element calculations an effort is made to propose the new analytical relationship between maximum K I and specimen a/W, which helps to estimate maximum K I by only knowing specimen geometry and applied load.

International Journal of Engineering, Science and Technology, Sep 28, 2010

Studies on crack-tip plastic zones are of fundamental importance in describing the process of fai... more Studies on crack-tip plastic zones are of fundamental importance in describing the process of failure and in formulating various fracture criteria. Minimum plastic zone radius (MPZR) theory is widely used in prediction of crack initiation angle in mixed mode fracture analysis of engineering materials. In this study, shape and size of mixed mode (I/II) crack-tip plastic zones have been estimated by finite element analysis in a four point bend specimen according to von Mises yield criteria. The results obtained are used to analyze the MPZR criterion with respect to the effective stress intensity factor (K eff) and elastic mode mixity (M e).

Fatigue of Aircraft Structures

The effect of an anticorrosive layer on the fatigue life of 2024-T-351-aluminium alloy has been s... more The effect of an anticorrosive layer on the fatigue life of 2024-T-351-aluminium alloy has been studied in the present investigation. The fatigue tests were conducted on the aluminium alloy with and without anodizing to evaluate the fatigue life. The results indicate that the fatigue life of the anodized specimens is significantly shorter than that of untreated specimens. Further, experiments were conducted to evaluate the effect of the anodizing process parameters on the fatigue life of anodized specimens. These results show that the fatigue life of anodized aluminium alloy can be improved by controlling the anodizing process parameters such as process temperature, voltage, and time of immersion.