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1

Status on pre-surgical deformation apparatus for fracture fixation plates

Malekani J., Yarlagadda P. K. D. V., Schmutz B., Schuetz M.

Archives of Materials Science and Engineering

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2015

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Vol. 72, nr 2

53--60

EN

Purpose: This paper reviews the apparatus used for deformation of bone fracture fixation plates during orthopaedic surgeries including surgical irons, pliers and bending press tools. This paper extends the review to various machineries in non-medical industries and adopts their suitability to clinics-related applications and also covers the evolution of orthopaedic bone plates. This review confirms that none of the studied machineries can be implemented for the deformation of bone fracture fixation plates during orthopaedic surgeries. In addition, this paper also presents the novel apparatus that are designed from scratch for this specific purpose. Several conceptual designs have been proposed and evaluated recently. It has been found that Computer Numerical Control (CNC) systems are not the golden solution to this problem and one needs to attempt to design the robotic arm system. A new design of robotic arm that can be used for facilitating orthopaedic surgeries is being completed.

2

The mechanical characteristics of phosphate glasses under high temperature and friction-induced cross-linking processes

Pawlak Z., Yarlagadda P. K. D. V., Frost R., Hargreaves D.

Journal of Achievements in Materials and Manufacturing Engineering

|

2009

|

Vol. 37, nr 2

458-465

EN

Purpose: In the present study, we consider mechanical properties of phosphate glasses under high temperature-induced and under friction-induced cross-linking, which enhance the modulus of elasticity. Design/methodology/approach: Two nanomechanical properties are evaluated, the first parameter is the modulus of elasticity (E) (or Young’s modulus) and the second parameter is the hardness (H). Zinc meta-, pyro - and orthophosphates were recognized as amorphous-colloidal nanoparticles were synthesized under laboratory conditions and showed antiwear properties in engine oil. Findings: Young’s modulus of the phosphate glasses formed under high temperature was in the 60-89 GPa range. For phosphate tribofilm formed under friction hardness and the Young’s modulus were in the range of 2-10 GPa and 40-215 GPa, respectively. The degree of cross-linking during friction is provided by internal pressure of about 600 MPa and temperature close to 1000şC enhancing mechanical properties by factor of 3 (see Fig. 1). Research limitations/implications: The addition of iron or aluminum ions to phosphate glasses under high temperature - and friction-induced amorphization of zinc metaphosphate and pyrophosphate tends to provide more cross-linking and mechanically stronger structures. Iron and aluminum (FeO4 or AlO4 units), incorporated into phosphate structure as network formers, contribute to the anion network bonding by converting the P=O bonds into bridging oxygen. Future work should consider on development of new of materials prepared by sol-gel processes, eg., zinc (II)-silicic acid. Originality/value: This paper analyses the friction pressure-induced and temperature–induced the two factors lead phosphate tribofilm glasses to chemically advanced glass structures, which may enhance the wear inhibition. Adding the coordinating ions alters the pressure at which cross-linking occurs and increases the antiwear properties of the surface material significantly.

3

External pressure in the hardening of phosphate in tribofilm on iron surfaces

Pawlak Z., Yarlagadda P. K. D. V., Hargreaves D., Frost R., Rauckyta T., Zak S.

Journal of Achievements in Materials and Manufacturing Engineering

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2009

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Vol. 33, nr 1

35-40

EN

Purpose: In the present work we consider our (in progress) spectroscopy study of zinc and iron phosphates under the influence external high pressure to determine zinc ion change coordination from tetrahedral to octahedral (or hexahedral) structure. Design/methodology/approach: The standard equipment is the optical high pressure cell with diamond (DAC). The DAC is assembled and then vibrational or electronic spectra are collected by mounting the cell in an infrared, Raman, EXAFS or UV-visible spectrometer. Findings: Mechanism by which zinc and iron methaphosphate material is transformed to glassy meta-phosphate is enhancing mechanical properties of tribofilm. The two decades of intensive study demonstrates that Zn (II) and Fe (III) ions participate to cross-link network under friction, hardening the phosphate. Research limitations/implications: Transition metal atoms with d orbital have flexible coordination numbers, for example zinc acts as a cross-linking agent increasing hardness, by changing coordination from tetrahedral to octahedral. Perhaps the external pressure effect on the [Zn–(O-P-)4 ] complex causes a transformation to an [Zn –(O-P-)6] grouping. Originality/value: This paper analyses high-pressure spectroscopy which has been applied for the investigation of 3D transition metal ions in solids. When studying pressure effects on coordination compounds structure, we can expect changes in ground electronic state (spin-crossovers), electronic spectra due to structural distortions (piezochromism), and changes in the ligand field causing shifts in the electronic transitions.

4

Design of automatic vision-based inspection system for solder joint segmentation

Mar N. S. S., Fookes C., Yarlagadda P. K. D. V.

Journal of Achievements in Materials and Manufacturing Engineering

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2009

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Vol. 34, nr 2

138-151

EN

Purpose: Computer vision has been widely used in the inspection of electronic components. This paper proposes a computer vision system for the automatic detection, localisation, and segmentation of solder joints on Printed Circuit Boards (PCBs) under different illumination conditions. Design/methodology/approach: An illumination normalization approach is applied to an image, which can effectively and efficiently eliminate the effect of uneven illumination while keeping the properties of the processed image the same as in the corresponding image under normal lighting conditions. Consequently special lighting and instrumental setup can be reduced in order to detect solder joints. These normalised images are insensitive to illumination variations and are used for the subsequent solder joint detection stages. In the segmentation approach, the PCB image is transformed from an RGB color space to a YIQ color space for the effective detection of solder joints from the background. Findings: The segmentation results show that the proposed approach improves the performance significantly for images under varying illumination conditions. Research limitations/implications: This paper proposes a front-end system for the automatic detection, localisation, and segmentation of solder joint defects. Further research is required to complete the full system including the classification of solder joint defects. Practical implications: The methodology presented in this paper can be an effective method to reduce cost and improve quality in production of PCBs in the manufacturing industry. Originality/value: This research proposes the automatic location, identification and segmentation of solder joints under different illumination conditions.

5

Arc voltage behavior in GMAW-P under different drop transfer modes

Praveen P., Kang M. J., Yarlagadda P. K. D. V.

Journal of Achievements in Materials and Manufacturing Engineering

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2009

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Vol. 32, nr 2

196-202

EN

Purpose: Experimental measurements have been made to investigate meaning of the change in voltage for the pulse gas metal arc welding (GMAW-P) process operating under different drop transfer modes. Design/methodology/approach: Welding experiments with different values of pulsing parameter and simultaneous recording of high speed camera pictures and welding signals (such as current and voltage) were used to identify different drop transfer modes in GMAW-P. The investigation is based on the synchronization of welding signals and high speed camera to study the behaviour of voltage signal under different drop transfer modes. Findings: The results reveal that the welding arc is significantly affected by the molten droplet detachment. In fact, results indicate that sudden increase and drop in voltage just before and after the drop detachment can be used to characterize the voltage behaviour of different drop transfer mode in GMAW-P. Research limitations/implications: The results show that voltage signal carry rich information about different drop transfer occurring in GMAW-P. Hence it’s possible to detect different drop transfer modes. Future work should concentrate on development of filters for detection of different drop transfer modes. Originality/value: Determination of drop transfer mode with GMAW-P is crucial for the appropriate selection of pulse welding parameters. As change in drop transfer mode results in poor weld quality in GMAW-P, so in order to estimate the working parameters and ensure stable GMAW-P understanding the voltage behaviour of different drop transfer modes in GMAW-P will be useful. However, in case of GMAW-P hardly any attempt is made to analyse the behaviour of voltage signal for different drop transfer modes. This paper analyses the voltage signal behaviour of different drop transfer modes for GMAW-P.

6

Teaching manufacturing engineering at tertiary institutions in conjunction with engineering design and engineering materials

Kosse V., Yarlagadda P. K. D. V.

Journal of Achievements in Materials and Manufacturing Engineering

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2008

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Vol. 31, nr 2

862-866

EN

Purpose: In this paper we discuss the innovative curriculum structure, teaching and learning approaches of coherent delivery of manufacturing in conjunction with engineering design and materials from year one to year four, including specializations, real life projects and final year projects. Design/methodology/approach: Tertiary institutions now face serious challenges. Modern industry requires engineering graduates with strong knowledge of modern technologies, highly practical focus, management skills, ability to work individually and in a team, understanding of environmental issues and many other skills and graduate attributes. Institutions in the tertiary sector change courses and modify curriculum to reflect challenges of the modern industry and make engineering graduates better prepared for the "real world". Findings: Queensland University of Technology, in response to industry requirements has re-designed the engineering curriculum with some integrated units. An integrated approach was adopted for the teaching of Materials Manufacturing and Design. This is further strengthened by various forms of final year projects. This includes industry based CEED projects as well as SAE Formula A Motorsport. Practical implications: Queensland University of Technology in the recent years introduced an innovative structure of engineering courses with a common core for Bachelor of Engineering Mechanical, Infomechatronics and Medical, where manufacturing is taught in conjunction with engineering design and engineering materials. Originality/value: Students survey indicates that the integrated approach enhances their learning and that the industry based projects help them to be better prepared for graduate work as well improving their communication skills.

7

Determination of the financial impact of machine downtime on the post large letters sorting process

Fox J. P., Brammall J. R., Yarlagadda P. K. D. V.

Journal of Achievements in Materials and Manufacturing Engineering

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2008

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Vol. 31, nr 2

732-738

EN

Purpose: The work outlined in this paper has aimed to develop the first comprehensive methodology for determining the cost of downtime, with particular application to the Australia Post's automated mail processing machines. Design/methodology/approach: Machine downtime, whether planned or unplanned, is intuitively costly to manufacturing organisations, however is often very difficult to quantify. Costing processes are rarely undertaken within manufacturing organisations. It has previously been estimated that 80% of industrial facilities were unable to accurately cost downtime, with many facilities underestimating the total cost by a factor of 200-300%. Findings: Models that did exist rarely considered more than a subset of the costs identified elsewhere, leading to overly conservative estimations. In addition, because cost definitions are not consistent, methodologies for evaluating and quantifying individual costs have not previously been adequately defined. Practical implications: It was also acknowledged that the lack of practical guides has hindered costing procedures of any nature being implemented more readily. Originality/value: The method presented may be applied to any manufacturing environment which would benefit from a more complete understanding of the magnitude of the cost of machine or process downtime.

8

Design of a wind tunnel for separating flower parts of saffron

Emadi B., Yarlagadda P. K. D. V.

Journal of Achievements in Materials and Manufacturing Engineering

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2008

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Vol. 31, nr 2

635-638

EN

Purpose: The separation possibility of stigma from the other parts of saffron flower using its aerodynamic properties was studied and a vertical wind tunnel was designed on the basis of the obtained results. Design/methodology/approach: Terminal velocities of three parts of saffron flower, including petal, stigma and anther within four days after harvest were investigated. Significant difference between terminal velocity of stigma (2.4-2.8 m/s) and the other parts (1-2 m/s) of flower on the first day after harvesting, revealed that accurate separation using air stream is possible. Equal friction method was applied for design. A vertical wind tunnel applying a fan with a flow rate of 1700 m3/h and a static pressure of 0.82 cm was designed for stigma separation of saffron flower from the other parts. The duct of introduced wind tunnel was sized equal to 40.6 x 40.6 cm for main, 40.6 x 33 and 40.6 x 18 cm for lateral branches. Research limitations/implications: Operation mechanization of harvest and post-harvest of saffron flower is economically important due to time limitation, daily harvesting, and possible contamination due to manual operations. Practical implications: A vertical wind tunnel aimed to use for processing of saffron flower was designed. The investigation result on terminal velocity measurement of three main parts of the flower showed that separation stigma from the other parts of flower is possible. Originality/value: The results showed that the separation of stigma from the other parts is definitely possible due to a significant difference of their terminal properties, especially on the first day of harvesting. Therefore, a vertical wind tunnel on the basis of obtained results was designed.

9

Applicability valuation for evaluation of surface deflection in automotive outer panels

Park D. H., Bae W. R., Jeong H. J., So B. S., Ko T. J., Yarlagadda P. K. D. V.

Journal of Achievements in Materials and Manufacturing Engineering

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2008

|

Vol. 31, nr 2

558-564

EN

Purpose: Upon unloading in a forming process there is elastic recovery, which is the release of the elastic strains and the redistribution of the residual stresses through the thickness direction, thus producing surface deflection. It causes changes in shape and dimensions that can create major problem in the external appearance of outer panels. Thus surface deflection prediction is an important issue in sheet metal forming industry. Many factors could affect surface deflection in the process, such as material variations in mechanical properties, sheet thickness, tool geometry, processing parameters and lubricant condition. Design/methodology/approach: Numerical simulation of process was performed by the use of finite element method, paying attention particularly to the thickness distribution and surface deflection of the drawn outer panel and the outline flange during forming. Simulation procedures of automotive outer panel as large size shape are as follows; 1) Acquisition of drawing parts 2) Laser scanning for generating CAD model 3) CAD model generation 4) Simulation model operation 5) Simulation execution and analyses of simulation results. Findings: The development of automation in stamping and assembly processes of automobile manufacture will require an excellent surface quality of formed panels and also their accurate dimensions. Practical implications: The use of high strength steel sheets in the manufacturing of automobile outer panels has increased in the automotive industry over the years because of its lightweight and fuel-efficient improvement. But one of the major concerns of stamping is surface deflection in the formed outer panels. Hence, to be cost effective, accurate prediction must be made of its formability. The automotive industry places rigid constraints on final shape and dimensional tolerances as well as external appearance quality of outer panels. The numerical simulation makes it possible to design and optimize the total process to a level, which can't be reached by traditional theoretical and experimental methods. Originality/value: Computer simulations can be used to determine the influence from variations in material properties and process parameters.

10

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

Gudimetla P., Yarlagadda P. K. D. V.

Journal of Achievements in Materials and Manufacturing Engineering

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2007

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Vol. 23, nr 1

7-14

EN

Purpose: Abrasive waterjet cutting involves use of a high pressure, abrasive laden waterjet at transsonic 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. 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 by Kim & Zeng. 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. Research limitations/implications: The finite element framework presented is idealized for the case of regular cubes based on a set of assumptions. 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.

11

Development of real-time data filtering for SCADA system

Wiliem L., Hargreaves D., Stapelberg R. F., Yarlagadda P. K. D. V.

Journal of Achievements in Materials and Manufacturing Engineering

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2007

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Vol. 21, nr 2

89-92

EN

Purpose: Purpose to develop a suitable algorithm to filter data from the SCADA system. Design/methodology/approach: A real-time filtering method for SCADA system is developed by capturing the occurence of data change in SCADA data, which is followed by recording several data before this data change occurs. Then, the algorithm is modeled and developed and in the final step an experiment to verify the algorithm is conducted. Finally, the result from the experiment is analysed to check the effectiveness of the algorithm. Findings: As a result, SCADA data analysis will be easier to conduct since only essential information is left. In fact, in comparison to the entire data collection, only around 8-22% of data is changed. Research limitations/implications: By utilizing this algorithm, data will be easier to conduct since only the essential information as a starting point of analyses is left. However, this paper only describes the reasons and steps of data filtering algorithm development, how the algorithm works and the result after it is implemented to analyse data from the SCADA system. Further analyses to the data filtering results haven't been done yet. The next step will be to analyse the results in order to establish the root cause of why the data is changing. Originality/value: It has been noted in many research papers that the SCADA system is able to increase the efficiency of the monitoring itself. However, the SCADA system creates a huge amount of data which is difficult to analyse. This paper proposes a real-time data filtering for the SCADA system. The philosophy that is applied in this algorithm is only to "catch" the occurrence of data change in SCADA data, which is followed by recording several data before this data changes. As a result, SCADA data analysis will be easier to be conducted since only essential information is left. In fact compared to the entire data collection, only around 8-22% of data is changed. Therefore, this method is highly suitable for the SCADA system.

12

Detection of short circuit in pulse gas metal arc welding process

Yarlagadda P. K. D. V., Praveen P., Madasu V. K., Rhee S.

Journal of Achievements in Materials and Manufacturing Engineering

|

2007

|

Vol. 24, nr 1

328-332

EN

Purpose: The paper discusses several methods of detecting occurrence of short circuit and short circuit severity in pulse gas metal arc welding process (GMAW-P). Design/methodology/approach: Welding experiments with different values of pulsing parameter and simultaneous recording of high speed camera pictures and welding signals (such as current and voltage) were used to identify the occurrence of short circuit and its severity in GMAW-P process. The investigation is based on the measurement of welding signals specifically current and voltage signals and their synchronization with high speed camera to investigate the short circuit phenomenon in GMAW-P process. Findings: The results reveal that short circuit can be detected using signal processing techniques and its severity can be predicted by using statistical models and artificial intelligence techniques in GMAW-P process. Research limitations/implications: Several factors are responsible for short circuit occurrence in GMAW-P process. The results show that voltage and current signal carry rich information about the metal transfer and especially short circuit occurrence in GMAW-P process. Hence it's possible to detect short circuit occurrence in GMAW-P process. Future work should concentrate on development of advance techniques to improve reliability of techniques mentioned in this paper for short circuit detection and prediction in GMAW-P process. Originality/value: For achieving atomization of the welding processes, implementation of real time monitoring of weld quality is essential. Specifically for GMAW-P process which is widely used for light weight metal which is widely gaining popularity in manufacturing industry. However, in case of GMAW-P process hardly any attempt is made to analyse techniques to detect and predict occurrence of short circuit. This paper analyses different techniques that can be employed for real time monitoring and prediction of short circuit and its severity in the GMAW-P process.

13

The mechanical strength of phosphates under friction-induced cross-linking

Pawlak Z., Yarlagadda P. K. D. V., Frost R., Hargreaves D.

Journal of Achievements in Materials and Manufacturing Engineering

|

2006

|

Vol. 17, nr 1-2

201--204

EN

Purpose: In the present study, we consider mechanical properties of phosphate glasses under high temperature-induced and under friction-induced cross-linking, which enhance the modulus of elasticity. Design/methodology/approach: Two nanomechanical properties are evaluated, the first parameter is the modulus of elasticity (E) (or Young’s modulus) and the second parameter is the hardness (H). Zinc meta-, pyro - and orthophosphates were recognized as amorphous-colloidal nanoparticles were synthesized under laboratory conditions and showed antiwear properties in engine oil. Findings: Young’s modulus of the phosphate glasses formed under high temperature was in the 60-89 GPa range. For phosphate tribofilm formed under friction hardness and the Young’s modulus were in the range of 2-10 GPa and 40-215 GPa, respectively. The degree of cross-linking during friction is provided by internal pressure of about 600 MPa and temperature close to 1000°C enhancing mechanical properties by factor of 3 (see Fig 1). Research limitations/implications: The addition of iron or aluminum ions to phosphate glasses under high temperature - and friction-induced amorphization of zinc metaphosphate and pyrophosphate tends to provide more cross-linking and mechanically stronger structures. Iron and aluminum (FeO4 or AlO4 units), incorporated into phosphate structure as network formers, contribute to the anion network bonding by converting the P=O bonds into bridging oxygen. Future work should consider on development of new of materials prepared by sol-gel processes, eg., zinc (II)-silicic acid. Originality/value: This paper analyses the friction pressure-induced and temperature–induced the two factors lead phosphate tribofilm glasses to chemically advanced glass structures, which may enhance the wear inhibition. Adding the coordinating ions alters the pressure at which cross-linking occurs and increases the antiwear properties of the surface material significantly

14

Arc voltage behavior of one drop per pulse mode in GMAW-P

Praveen P., Kang M. J., Yarlagadda P. K. D. V.

Journal of Achievements in Materials and Manufacturing Engineering

|

2006

|

Vol. 17, nr 1-2

389--392

EN

Purpose: Experimental measurements have been made to investigate the meaning of the change in voltage for the pulse gas metal arc welding process through one drop per pulse mode (ODPP). Design/methodology/approach: Welding experiments with different values of pulsing parameter and simultaneous recording of high speed camera pictures and welding signals (such as current and voltage) were used to identify ODPP drop transfer mode in pulse gas metal arc welding. The investigation is based on the synchronization of welding signals and high speed camera to study the behaviour of voltage signal under ODPP. Findings: The results reveal that the welding arc is significantly affected by the molten droplet detachment. In fact, sudden increase and drop in voltage just before and after the drop detachment characterizes the voltage behaviour of ODPP drop transfer mode in pulse gas metal arc welding. Research limitations/implications: The results show that voltage signal carry rich information about different drop transfer occurring in pulse gas metal arc welding. Hence it’s possible to detect different drop transfer modes. Future work should concentrate on development of filters for detection of different drop transfer modes. Originality/value: Determination of drop transfer mode with pulse gas metal arc welding is crucial for the appropriate selection of pulse welding parameters. As change in drop transfer mode results in poor weld quality in pulse gas metal arc welding, so in order to estimate the working parameters and ensure stable pulse gas metal arc welding understanding the voltage behaviour of different drop transfer modes in pulse gas metal arc welding will be useful. However, in case of pulse gas metal arc welding hardly any attempt is made to analyse the behaviour of voltage signal for different drop transfer modes. This paper analyses the voltage signal behaviour of ODPP mode for pulse gas metal arc welding. ODPP mode widely used to achieve best quality weld.