Finite element analysis of the interaction between an AWJ particle and a polycrystalline alumina ceramic

Purpose: Abrasive waterjet cutting involves use of a high pressure, abrasive laden waterjet at trans-sonic speeds to cut difficult-to-machine materials. The jet-material interaction depends on the nature of the material being cut, such as ductile or brittle. The brittle regime involves the generation and propagation of microcracks due to impact and many theories have been proposed in this regard. We aim to resolve the nature of the generation and propagation of cracks in such phenomena using the finite element analysis methodology.\ud Design/methodology/approach: A 3-dimensional FE model was set up using PATRAN. The alumina ceramic was modelled as a 1-mm cube while a 0.1mm diameter half sphere was used to model a single abrasive particle. The system was imported into ABAQUS and an explicit analysis was performed. The element deletion method was used after invoking a failure criterion to estimate the number of elements removed due to a single impact. The aggregate volume of eroded material was then calculated by multiplying the number of elements removed with the volume of each element. The results of the FEA were compared with the brittle model proposed\ud by Kim & Zeng [12].\ud Findings: The results of the FEA indicate that mixed-mode failure is the most common form of failure in such interactions. The volume of material removed per impact from the FE results is close to 16% of those predicted by Kim & Zeng’s model.\ud Research limitations/implications: The finite element framework presented is idealized for the case of regular cubes based on a set of assumptions.\ud Originality/value: This finite element approach is a good tool to study the nature of interaction between a microscopic particle and a brittle material and accurately predict the erosion mechanisms in such interactions

Puncture resistance of pressurized and unpressurized glass reinforced Epoxy (GRE) pipes : a phenomenological model of failure mechanisms

Glass reinforced ethylene (GRE) pipes are widely used in the oil and gas sector in Australia owing to their economical/competitive life cycle costs. However, as with all pipelines, GRE pipes face significant risks of external interference by earthmoving equipment where mechanical insult is the result of approximately 50% of pipeline failures. Mechanical tests on un-pressurised pipes were conducted on thick and thin walled GRE pipe samples rated to ANSI Class 600 at different loading rates to study the failure mechanisms. Localised failures due to combined bending and shear with severe delamination under the indenter were observed in thick wall GRE whereas thin walled GRE pipes failed due to buckling away from the point of impact. The finite element analyses results show that GRE pipes fail due to a combination of bending and direct shear at the p oint of impact. Further, the failures are functions of the angle of impact and the tip geometry. The magnitude of puncture resistance as well as the location of failure and failure mechanisms were all found to be highly dependent on the pipe wall thickness and applied internal pressure. GRE pipes exhibited 55 to 75% less resistance to puncture as compared with steel pipes of same wall thickness. Hence, most commercially available excavators have the potential to penetrate GRE pipes, so alternative methods must be employed to reduce this risk

Internal positioning system for cardiotocograph (CTG) transducers at Mackay Base Hospital

Gudimetla, PV ORCiD: 0000-0002-9402-1763© 2019 The Authors. Published by Elsevier Ltd. Cardiotocographs (CTG) are essential pieces of medical equipment that assist in the birth suite and during maternity surveillance. These devices require the use of transducers that communicate wirelessly to the CTG and enable an expectant mother to have water births. When the CTG transducers are lost, or misplaced, there is no system that can locate the expensive accessories. Thus, necessitates the need to develop an Internal Positioning System at Mackay Base Hospital. The device that was proposed to be used in the system is an Xbee S68© Wi-Fi RF module designed by DIGI International. This device is capable of communicating to Access Points for the purposes of location tracking only. It was successfully demonstrated on a small home network that the Xbee device was able to transmit/ receive data from characteristic packet signatures which was captured using Wireshark©. Furthermore, to ensure the device can be aligned with IP67 rating an enclosure was designed to enable the device to be immersed in water. Overall it was ascertained that the device is able to connect on a small network, which can be easily applied on a larger WLAN, in addition to all the project outcomes of an Engineering style report was demonstrated

Finite element analysis of high strain rate superplastic forming (SPF) of Al–Ti alloys

Presents the numerical results obtained from the finite element analyses of the superplastic forming (SPF) of Al–Ti alloys. The models are used to optimise the process and predict forming times in terms of deformed shapes, stress–strain distributions and thickness evolution across the facets of fully formed surfaces. Unlike earlier studies that have used membrane elements, this is an exercise using shell elements in an attempt to estimate stresses, slip planes and variation of friction coefficients during the forming process. The simulations were validated using previously reported experimental results. The constitutive modelling was based on the elastic–viscoplastic material properties, taking into account the viscous flow parameters of the sheet metal. ABAQUS/standard finite element code was used to simulate the SPF process. The results indicate good correlation amongst the theoretical, experimental and finite element analyses

Properties of tough skinned vegetable-pumpkin tissue

Gudimetla, PV ORCiD: 0000-0002-9402-1763Understanding of mechanical behaviour of food particles will provide researchers and designers essential knowledge to improve and optimise current food industrial technologies. Understanding of tissue behaviours will lead to the reduction of material loss and enhance energy efficiency during processing operations. Although, there are some previous studies on properties of fruits and vegetables however, tissue behaviour under different processing operations will be different. The presented paper is a part of FE modelling and simulation of tissue damage during mechanical peeling of tough skinned vegetables. In this study indentation test was performed on peeled and unpeeled samples at loading rate of 20 mm/min for peel, flesh and unpeeled samples. Consequently, force deformation and stress and strain of samples were calculated. The toughness of the tissue also has been calculated and compared with the previous result

Beyond the technical skills: A case for internationalization of graduate attributes in PhD programs

Gudimetla, PV ORCiD: 0000-0002-9402-1763Internationalization of curriculum (IoC) has garnered momentum, with many universities around the world now viewing graduate students as global citizens. One aspect of IoC that lacks clarity is the students’ perception of internationalization of graduate attributes. In this study, we explored graduate student’s perceptions of the graduate attributes that need to be included in the curriculum to become internationalized. Advanced stage PhD students (n=6) were interviewed about the relevance of internationalization of specific graduate attributes. A set of six specific questions were posed in the interview that was conducted as a group discussion and was recorded and transcribed. 5 out of 6 students observed that schools, faculties, and universities need to sponsor workshops and seminars regularly which will help students absorb attributes such as cultural and religious tolerance, societal awareness, stress management, building resilience which will help them fit well into any work environment. Another important factor was the need for more exchange programs and conference participation that will expose them to different work environments worldwide and help them recognize how their peers approach similar endeavors. Our study offers insights into what aspects of graduate attributes need to be addressed at the faculty and university levels to promote the IoC. © 2019 by authors, all rights reserved

Modelling and simulation of performance and combustion characteristics of diesel engine

Gudimetla, PV ORCiD: 0000-0002-9402-1763; Nabi, M ORCiD: 0000-0002-4087-930X; Rasul, M ORCiD: 0000-0001-8159-1321The main objective of this study was to develop a thermodynamic model to analyse engine performance and combustion behavior of a single cylinder, four-stroke, naturally aspirated, direct injection (DI) diesel engine. The model was developed with a commercial GT-Power software. Various sub-models for different systems including intake, exhaust, fuel injection, combustion, and heat transfer rate were combined for thermodynamic analysis of engine performance and combustion behaviour. The engine rotational speed, start of injection timing and compression ratio were considered as variables. The engine rotational speeds were varied from 800 rpm to 2500 rpm, the start of injection timings was ranged from 15o crank angle (CA) before top dead centre (bTDC) to 15o CA after top dead centre (aTDC), and the compression ratios were changed from 13 to 25. Performance parameters such as indicated and brake power, brake thermal efficiency, friction, etc. and combustion parameters such as heat transfer rate and in-cylinder pressure are analysed at different engine rotational speed, injection timing, and compression ratio, and discussed accordingly. The optimum performance such as BTE, BT and BMEP were found at the engine speed of 1700 rpm, a start of injection timing of 10o bTDC, and a compression ratio of 20. © 2019 The Authors. Published by Elsevier Ltd

A finite element analysis of the hydrodynamic performance of 3- and 4-Fin surfboard configurations

This study investigates the hydrodynamic performance of three and four fin surfboard configurations using the CFD/CFX approach. CFD models of three and four fin configurations were setup inside a rectangular domain using CFX meshing. Comparisons of performance were evaluated by analysing both lift and drag coefficients for each fin system as a function of the angle of incidence at various speeds. The 2-equation k-epsilon (k-ε) turbulence model was used as the base for simulations of flow velocities of 3, 5, 7 and 10 m/s. In addition the 7-equation Reynolds stress (RSM) turbulence model was also employed for flow velocities of 10 and 25m/s in order to compare the predictions of the k-ε turbulence model. Results demonstrated that the maximum lift for the three fin configuration occurred at a smaller angle of incidence than for the four fin design. However, the magnitude of maximum lift was the same for both designs under the operating conditions considered in this study. The results from this investigation imply that if a surfer desires a greater degree of manoeuvrability (ideal in regular surfing), then the three fin configuration would be more appropriate in comparison to the four fin configuration. This is because the three fin design is more efficient at generating lift during smaller angles of attack compared to the four fin design. However if stability and speed in the surfboard is preferred (favourable in big wave surfing), then the four fin configuration would be more suitable owing to less lift and drag at smaller incidence angles

Impact & energy absorption of road safety barriers by coupled SPH/FEM

Gudimetla, PV ORCiD: 0000-0002-9402-1763Road safety barriers are used to minimise the severity of road accidents and protect lives and property. There are several types of barrier in use today. This paper reports the initial phase of research carried out to study the impact response of portable water-filled barrier (PWFB) which has the potential to absorb impact energy and hence provide crash mitigation under low to moderate speeds. Current research on the impact and energy absorption capacity of water-filled road safety barriers is limited due to the complexity of fluid-structure interaction under dynamic impact. In this paper, a novel fluid-structure interaction method is developed based on the combination of Smooth Particle Hydrodynamics (SPH) and Finite Element Method (FEM). The sloshing phenomenon of water inside a PWFB is investigated to explore the energy absorption capacity of water under dynamic impact. It was found that water plays an important role in energy absorption. The coupling analysis developed in this paper will provide a platform to further the research in optimising the behaviour of the PWFB. The effect of the amount of water on its energy absorption capacity is investigated and the results have practical applications in the design of PWFBs

Enhancing student learning experience with a simulation tool in engineering dynamics

Gudimetla, PV ORCiD: 0000-0002-9402-1763; Jayasuriya, AU ORCiD: 0000-0003-4908-0809; Roy, SM ORCiD: 0000-0002-4952-5858Engineering Dynamics is a core Mechanical Engineering course that underpins fundamental knowledge that is applied in many advanced courses in the upper levels of the program. This second-year course applies principles from Physics and Mathematics to describe the motion and energy transmission characteristics of all moving objects. For students to understand such characteristics, it is imperative they can visualise the way forces incite motion in bodies and how bodies in turn, react to such forces. The field of Engineering Dynamics has seen the use of numerous multimedia technologies to promote and enhance student learning. This paper covers implementation of a new state-of-the-art interactive simulation tool and aims to evaluate the enhancement in student learning experiences with the implementation of this tool. All students in this unit are asked to complete the pre- and post-simulation surveys which are used as part of the general running of the course to help students assess their level of understanding and preparedness for the course. The surveys are scheduled every fortnight as the target concepts are taught progressively during the duration of the course. Interviews are conducted with volunteer students during the delivery the course to identify how they found the simulation software helpful in creating a better understanding of the concepts. This research has the benefits of using this interactive software to learn Engineering Dynamics and develop guidelines for its effective use in creating better learning experiences and enhanced student satisfaction. This study helped to develop strategies for teaching different concepts in Engineering Dynamics with use of the simulation platform. This research shows that the use of Interactive Physics has enhanced the learning experience considerably and helped not only to understand the concepts in kinematics and kinetics, but also to know the mathematics behind it. It also helped make connections between physics and mathematics behind the various dynamics problems and effective and simplified the problem statement