Saravanan Karuppanan

Contact Stress Evaluation of Involute Gear Pairs, Including the Effects of Friction and Helix Angle

The aim of this paper is to provide a new viewpoint of friction factor for contact stress calculations of gears. The idea of friction factor has been coined, for the calculation of contact stresses along the tooth contact for different helical gear pairs. Friction factors were developed by evaluating contact stresses with and without friction for different gear pairs. In this paper, 3D Finite Element Method (FEM) and Lagrange Multiplier algorithm has been used to evaluate the contact stresses. Initially, a spur gear FE model was validated with the theoretical analysis under frictionless condition, which is based on Hertzs contact theory. Then, similar FE models were constructed for 5, 15, 25 and 35 deg. helical gear pairs. The contact stresses of these models were evaluated for different coefficients of friction. These results were employed for the development of friction factor.

Experimental Study of Low Velocity Impact Response of Carbon/Basalt Hybrid Filament Wound Composite Pipes

In this study, the impact damage resistance of carbon/basalt hybrid fiber reinforced polymer pipes was experimentally investigated under low velocity impact loading. The composite pipes, composed of thin plastic liner of HDPE wrapped with eight layers of plies at constant winding angle of [±55∘/902∘/±55∘/902∘], were fabricated through filament winding technique. Eight pipe configurations with different stacking sequence and fiber content proportion were studied. Specimens cut from the original pipes were tested in a drop weight impact machine under two levels of impact energies, 50J and 100J, in order to predict the impact response and induced damage resistance of the pipe. The damage of the tested pipes was assessed based on the force-displacement, force-time histories, the energy absorption mechanism, as well as the micrographs captured by scanning electron microscope (SEM) for the specimens. The results indicate that the impact resistance behavior was highly affected by the stacking sequence of the lay...

Study on Interlaminar Shear Strength of Angle Ply Oriented Basalt-Carbon Hybrid Composite

In this study inter-laminar shear strength of basalt-carbon hybrid composite was investigated experimentally and numerically. The finite element model was generated in ANSYS® software. The main aim of this paper was to determine the influence of fiber orientation on interlaminar shear strength, and to estimate the interlaminar shear strength of angle ply oriented basalt-carbon hybrid composite laminates. The tested specimens with varying orientations were prepared using hand lay-up technique. Short beam shear test under three point bending was performed through ASTM D2344. The input data for finite element analysis was obtained from three point bending test. Numerical results obtained from ANSYS showed good correlation with experimental results. From the obtained results of experimental and FEA analysis the effect of fiber orientation was proved on interlaminar shear strength of basalt-carbon hybrid composite laminates.

Scaled down Design of a Cold and Hot Flow Model Based on a Bubbling Fluidized Bed Pilot Plant Gasifier

Bubbling fluidized bed (BFB) is a vital equipment in many applications in the energy, pharmaceuticals, and chemicals process industries due to its numerous advantages such as large heat capacity inside a bed, and rapid heat and mass transfer rate. In spite of numerous research activities, achieving high fluidization performances in BFB process is still a challenge of science. This research is being conducted to study the hydrodynamic regime of a BFB pilot plant gasifier. To this end, a lab-scale cold model was first designed based on the empirical equations and scaling laws. The scaling laws was used to scale down the Tenaga Nasional Berhad-PETRONAS (TNBR-PETRONAS) pilot plant gasifier into a small scale laboratory model. Moreover, the empirical equations were utilized to determine the critical parameters such as bed pressure drop, height of the bed, number of orifices of the distributor plate and the pitch size. Finally a lab-scale hot flow model will be designed based on the cold model geometric dimensions but under a real operating conditions as that of a pilot plant.

Finite element analysis of residual stress in cold expanded plate with different thickness and expansion ratio

Cold expansion of fastener/rivet holes is a common way to generate beneficial compressive residual stress around the fastener hole. In this study, cold expansion process was simulated by finite-element method in order to determine the residual stress field around two cold expanded holes by varying the plate thickness and expansion ratio of the hole. The model was developed in ANSYS and assigned to aluminium alloy 7475-T61 material model. The results showed that the residual stress become more compressive as the plate thickness is increased up to t/d = 2.6 and decreased for further level of thickness. In addition, the residual stress at the edge of the hole become more compressive as the expansion ratio is increased up to 4.5% and decreased for further level of expansion. This study also found that the residual stresses near the entrance and the exit face of the plate are less compressive than the residual stresses on the mid-thickness of the plate.

Burst pressure investigation of filament wound type IV composite pressure vessel

Currently, composite pressure vessels (PVs) are employed in many industries such as aerospace, transportations, medical etc. Basically, the use of PVs in automotive application as a compressed natural gas (CNG) storage cylinder has been growing rapidly. Burst failure due to the laminate failure is the most critical failure mechanism for composite pressure vessels. It is predominantly caused by excessive internal pressure due to an overfilling or an overheating. In order to reduce fabrication difficulties and increase the structural efficiency, researches and studies are conducted continuously towards the proper selection of vessel design parameters. Hence, this paper is focused on the prediction of first ply failure pressure for such vessels utilizing finite element simulation based on Tsai-Wu and maximum stress failure criterions. The effects of laminate stacking sequence and orientation angle on the burst pressure were investigated in this work for a constant layered thickness PV. Two types of winding d...

Development of a Quantifiable Approach in Monitoring the Fatigue Cracks Using Digital Image Correlation

From the viewpoint of engineering, fatigue is an important issue as most of the mechanical failures are associated with fatigue damage. In fact, these disastrous events had occurred unexpectedly during the regular working conditions and most of the time the applied stresses are well below the yield strength of the material. Thus, it makes the prediction of fatigue damage a challenging task in the field of engineering, especially when the manmade structures and machines are getting more complex than before. Even though fatigue has been studied extensively in the past 170 years, many limitations are still being found within the current fatigue analysis, testing and the non-destructive inspection. Hence, there is a great need to develop a precise and yet efficient inspection technique in quantifying the fatigue cracks. Therefore, the objective of this study is to develop a quantifiable approach in monitoring the fatigue cracks using digital image correlation technique. This can be achieved by using a developed two-dimensional sub-pixel accuracy deformation measurement algorithm which determines the deformation parameters of the first-order shape function of a material subjected to cyclic loading. Next, fatigue tests for samples made of mild steel (Grade: JIS G 3101 SS400) were conducted in accordance to the ASTM E466. Simultaneously, an industrial grade camera was used to capture the fatigue crack’s region at a specific interval until the sample broke into two pieces. The captured images were then analysed and the deformation parameters such as translations, normal and shear strains values were determined by using the developed digital image correlation algorithm. Based on the determined deformation patterns, a specific trend was observed throughout the graphs of respective deformation parameters against the number of cycles. Besides, drastic changes were observed when the average number of cycles was approaching 95.5% (min. loading) and 93.8% (max. loading) of the total fatigue life. In conclusion, the digital image correlation technique was proven to be capable in monitoring the severity of a fatigue crack and the proposed monitoring system would serve as an inspection technique in examining the fatigue damage of a structural component throughout its operational period.

Effect of wear on the burst strength of l-80 steel casing

Casing wear has recently become one of the areas of research interest in the oil and gas industry especially in extended reach well drilling. The burst strength of a worn out casing is one of the significantly affected mechanical properties and is yet an area where less research is done The most commonly used equations to calculate the resulting burst strength after wear are Barlow, the initial yield burst, the full yield burst and the rupture burst equations. The objective of this study was to estimate casing burst strength after wear through Finite Element Analysis (FEA). It included calculation and comparison of the different theoretical bursts pressures with the simulation results along with effect of different wear shapes on L-80 casing material. The von Misses stress was used in the estimation of the burst pressure. The result obtained shows that the casing burst strength decreases as the wear percentage increases. Moreover, the burst strength value of the casing obtained from the FEA has a higher value compared to the theoretical burst strength values. Casing with crescent shaped wear give the highest burst strength value when simulated under nonlinear analysis.

Frictional Contact Stress Analysis of Spur Gear by using Finite Element Method

Spur gear is used to transfer rotary motion between parallel shafts. The simplicity in its design is one of the advantages of the spur gear. However higher frictional force that is accumulated on the gear teeth will influence the spur gear performance. Many previous papers elaborated extensively on the contact stress in the spur gear but few of them gave the details on how friction affects the gear teeth. There are insufficient frictional effect data in the gear and thus should be regarded as an important research parameter. In this paper, the contact stress of spur gear has been evaluated with and without friction by employing the Hertz theory, AGMA standard and finite element method (FEM). The frictionless contact stress result has been validated with both the theoretical methods with minimum deviation. Frictional coefficient range of 0.0 to 0.3 was selected and the corresponding contact stress is directly proportional to the friction coefficient. The work also involves the variation of face width of the gear set under the influence of friction. The contact stress of spur gear was found to be inversely proportional to the face width.

Finite Element Analysis of Casing Material Behavior in Steam Injection Well Operations

Casing design is one of the most important parts of the well planning in the oil and gas industry. Various factors affecting the casing material needs to be considered by the drilling engineers. Wells partaking in thermal oil recovery processes undergo extreme temperature variation and this induces high thermal stresses in the casings. Therefore, forecasting the material behavior and checking for failure mechanisms becomes highly important. This paper uses Finite Element Methods to analyze the behavior two of the frequently used materials for casing - J55 and L80 steels. Modeling the casing and application of boundary conditions are performed through Ansys Workbench. Effect of steam injection pressure and temperature on the materials is presented in this work, indicating the possibilities of failure during heating cycle. The change in diameter of the casing body due to axial restriction is also presented. This paper aims to draw special attention towards the casing design in high temperature conditions of the well.