J.R. Mohanty

Determination of fatigue crack growth rate from experimental data: A new approach

The determination of crack growth rate from laboratory observations of crack length and number of cycles is certainly a tedious job in order to considerably reduce the scatter in the test results. There are several curve-fitting methods currently in use including the standard ASTM methods. In this work, an alternative technique has been presented which has been found to be efficient in determining the crack growth rate in 2024-T3 and 7020-T7 aluminium alloy specimens.

Effect of Fiber Content on Abrasive Wear Behavior of Date Palm Leaf Reinforced Polyvinyl Pyrrolidone Composite

The effect of fiber contents on wear behavior of date palm leaf reinforced polyvinyl pyrrolidone (PVP/DPL) composites has been experimentally investigated. The test samples with fillers in 10, 20, 30, and 40% based on weight of fibers were prepared using injection molding. The optimum fiber content (i.e., 26 wt%) for maximum mechanical strength of the composites was determined by regression analysis. The dry sliding wear tests were conducted for each composition at different sliding velocities (0.392, 0.471, and 0.549 m/s) and sliding distances (188, 254, and 376 m) by applying normal loads of 5, 10, 15, and 20 N using pin-on-disc wear testing machine. The specific wear rate, wear loss, and coefficient of friction were plotted against the normal load and sliding distance at all sliding velocities. The results reveal that incorporation of date palm leaf fibers leads to significant improvement in the wear resistance of composites up to optimum fiber content and then decreases as fiber content increases. Further, it is found that surface modification has significant effect on wear performance. Worn surfaces of some selected samples were studied by scanning electron microscopy to analyze the wear mechanism.

Effect of chemically modified date palm leaf fiber on mechanical, thermal and rheological properties of polyvinylpyrrolidone

Polyvinylpyrrolidone/date palm leaf fiber (PVP/DPL) biocomposites were prepared by melt mixing fabrication technique with different weight percentage of fibers. DPL fibers were chemically modified by acrylic acid in order to have better dispersion and compatibility with PVP matrix. The interaction of DPL fibers with PVP matrix was studied by Fourier transforms infrared spectroscopy (FTIR). Field emission scanning electron microscope (FESEM) was used for the study the morphology of chemically modified DPL fibers and PVP/DPL biocomposites. Mechanical properties were improved with fiber loading due to strong interfacial adhesion between PVP and DPL fibers. The storage modulus, loss modulus and tan delta values of PVA/DPL biocomposites were measured by DMTA. The rheological properties were investigated to study the shearing storage and loss modulii along with complex viscosity of biocomposites. The thermal and conducting properties of biocomposites were measured and compared with that of virgin PVP.

Solid Particle Erosion of Date Palm Leaf Fiber Reinforced Polyvinyl Alcohol Composites

Solid particle erosion behavior of short date palm leaf (DPL) fiber reinforced polyvinyl alcohol (PVA) composite has been studied using silica sand particles (200 ± 50 μm) as an erodent at different impingement angles (15–90°) and impact velocities (48–109 m/s). The influence of fiber content (wt% of DPL fiber) on erosion rate of PVA/DPL composite has also been investigated. The neat PVA shows maximum erosion rate at 30° impingement angle whereas PVA/DPL composites exhibit maximum erosion rate at 45° impingement angle irrespective of fiber loading showing semiductile behavior. The erosion efficiency of PVA and its composites varies from 0.735 to 16.289% for different impact velocities studied. The eroded surfaces were observed under scanning electron microscope (SEM) to understand the erosion mechanism.

Prediction of constant amplitude fatigue crack growth life of 2024 T3 Al alloy with R-ratio effect by GP

A genetic programming approach (GP) for predicting fatigue crack growth rate (da/dN) of Al-alloy has been described.The crack growth rate has been calculated by using an exponential model from experimental crack length (a) and number of cycles (N) data which has been subsequently used as training data base for GP model formulation along with load ratio (R), maximum stress intensity factor (Kmax) and stress intensity factor rage (ΔK).The validity of the proposed GP model has been confirmed by comparing the model prediction by experimental data and also with previously proposed ANN model. The objective of this study is to develop a genetic programming (GP) based model to predict constant amplitude fatigue crack propagation life of 2024 T3 aluminum alloys under load ratio effect based on experimental data and to compare the results with earlier proposed ANN model. It is proved that genetic programming can effectively interpret fatigue crack growth rate data and can efficiently model fatigue life of the material system under investigation in comparison to ANN model.

Study of Mechanical, Thermal, and Rheological Properties of Areca Fiber-Reinforced Polyvinyl Alcohol Composite

ABSTRACT In the present work, polyvinyl alcohol (PVA) thermoplastic matrix has been reinforced by randomly oriented short areca sheath (AS) fiber to prepare PVA/AS composite by injection molding. The fiber has been chemically modified with benzyl chloride to have better compatibility with PVA matrix. Different mechanical properties such as tensile strength, Young’s modulus, flexural strength, flexural modulus, and impact strengths of the composite with varying weight percentage of treated fibers have been studied and the optimum weight percentage has been determined by regression analysis. It has been observed that the maximum values of mechanical properties of the composite are obtained at optimum weight percentage (i.e., 27 wt%) of AS fiber. The chemical interaction of polymers with fibers has been characterized by Fourier transform infrared spectroscopy, X-ray diffraction, and scanning electron microscopy at this fiber loading. The thermal properties of the composite have been studied through dynamic mechanical thermal analysis, thermal gravimetric analysis, and differential scanning calorimetry at optimum fiber loading. Rheological properties of the composite in terms of complex viscosity (η*), storage modulus (G′), loss modulus (G″), and damping factor (tan δ) have been investigated through a parallel plate rheometer and compared with virgin PVA. From the characterization and study of properties, it is observed that PVA/AS composite gives best performance at optimum fiber loading.

Investigation on solid particle erosion behavior of date palm leaf fiber- reinforced polyvinyl pyrrolidone composites

The present investigation reports about the solid particle erosion behavior of randomly oriented short date palm leaf (DPL) fiber-reinforced polyvinyl pyrrolidone composites. The erosion rates of these composites have been evaluated at different impingement angles (15–90°) and impact velocities (48–109 m/s). The neat polyvinyl pyrrolidone shows maximum erosion rate at 30° impingement angle, whereas, PVA/DPL composites exhibit maximum erosion rate at 45° impingement angle irrespective of fiber loading showing semi-ductile behavior. Erosion efficiency (η) values (2.83–15.29%) indicate micro-ploughing and micro-cutting as dominant wear mechanisms. The morphology of eroded surfaces was examined by scanning electron microscopy. Possible erosion mechanisms are discussed.

Application of Artificial Neural Network for Fatigue Life Prediction under Interspersed Mode-I Spike Overload

The objective of this study is to design multi-layer perceptron artificial neural network (ANN) architecture in order to predict the fatigue life along with different retardation parameters under constant amplitude loading interspersed with mode-I overload. Fatigue crack growth tests were conducted on two aluminum alloys 7020-T7 and 2024-T3 at various overload ratios using single edge notch tension specimens. The experimental data sets were used to train the proposed ANN model to predict the output for new input data sets (not included in the training sets). The model results were compared with experimental data and also with Wheeler’s model. It was observed that the model slightly over-predicts the fatigue life with maximum error of + 4.0 % under the tested loading conditions

Polyvinyl Chloride Reinforced with Areca Sheath Fiber Composites—An Experimental Study

ABSTRACT This research work deals with fibrous composites obtained by using treated and untreated areca sheath (AS) fibers reinforced in polyvinyl chloride (PVC) by injection molding process. Surface treatments of fibers have been carried out to have a better compatibility with PVC matrix. The tensile and flexural strength have been found to increase at the early stage with the increase in treated areca fiber content till optimum (18 wt% of fiber) fiber loading thereafter declines. At optimum fiber loading, the tensile strength, flexural strength and young’s modulus values are 42.38 MPa, 18.22 MPa and 2.38 GPa, respectively, which give maximum values in comparison to other fiber loadings. Thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), biodegradability tests and scanning electron microscopy (SEM) have been used for analysis. The TGA inferred that the thermal stability of the composites increased as compared to neat PVC matrix. Further, the composites exhibit excellent biodegradability property and their biodegradability increases with the increase of areca fiber content. From the properties obtained at optimum fiber loading (18 wt% of fiber), the composite can be suitable for automotive dashboard and door panel applications.

Influence of chemical treatment on tensile strength, water absorption, surface morphology, and thermal analysis of areca sheath fibers

ABSTRACT Proper surface modification is highly essential to improve compatibility of natural fibers with polymer matrix to develop eco-friendly materials. In the present work, an attempt has been made to study the effect of various chemical treatments such as alkaline, acrylic acid, permanganate, sodium chlorite, and benzoylation on areca sheath fiber. After surface modifications, its density, water absorption property, mechanical property, thermal gravimetry analysis (TGA), Fourier transform infrared spectroscopy (FTIR), and surface morphology have been thoroughly investigated. It has been observed that benzoyl chloride-treated fiber gives better performance in comparison to other treatments.