bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparison of Tribological Performances of High Density Polyethylene Enhanced With Carbon Nanofibers
Authors: Xu Songbo , Akchurin Aydar , Tangpong X. W. , Liu Tian , Wood Weston , Zhong Wei-Hong
Published: October 2013

High density polyethylene (HDPE) is widely used as bearing material in industrial application because of its low friction and high wear resistance properties. Carbon nanofiber (CNF) reinforced HDPE nanocomposites are promising materials for biomedical applications as well, such as being the bearing materials in total joint replacements. The main objective of the present study is to investigate how the wear of HDPE can be altered by the addition of either pristine or silane treated CNFs at different loading levels (0.5 wt.% and 3 wt.%). Two types of silane coating thicknesses, 2.8 nm and 46 nm, were applied on the surfaces of oxidized CNFs to improve the interfacial bonding strength between the CNFs and the matrix. The CNF/HDPE nanocomposites were prepared through melt mixing and hot-pressing. The coefficients of friction (COFs) and wear rates of the neat HDPE and CNF/HDPE nanocomposites were determined using a pin-on-disc tribometer under dry sliding conditions. The microstructures of the worn surfaces of the nanocomposites were characterized using both scanning electron microscope (SEM) and optical microscope to analyze their wear mechanisms. Compared with the neat HDPE, the COF of the nanocomposites were reduced. The nanocomposite reinforced with CNFs coated with the thicker silane coating (46 nm) at 0.5 wt.% loading level was found to yield the highest wear resistance with a wear rate reduction of nearly 68% compared to the neat HDPE.
Poly-Disperse Droplet Evaporation Model
Authors: Protheroe M. D. , Al-Jumaily A. M. , Nates R. J.
Published: October 2013

A model for the evaporation of micron-size, poly-disperse water droplets into air has been developed that allows the prediction of droplet size distribution changes during evaporation. The model incorporates either adiabatic or isothermal boundary conditions and allows for the variation of fluid transport and thermodynamic properties during the evaporation process. The governing equations for the model are developed from the coupled mass and energy balances for the droplets and for the surrounding air assuming they are flowing along a tube and assuming diffusion mass transport and conduction heat transfer processes predominate. Droplet sizes and temperatures as well as surrounding air temperature and humidity are all output as functions of time allowing droplet lifetimes and size distribution changes to be observed. The model, at this stage, is checked against overall mass and energy balances.
The Non-Uniform Preloading Effect on Stiffness Behaviour of Angular Contact Ball Bearings
Authors: Wu Wenwu , Hong Jun , Li Xiaohu , Li Yang , Li Baotong
Published: October 2013

With the increasing demand of higher operating speed for bearing system, more challenges have been exposed on the maintaining of the bearing performance. Preloading is an effective method to handle these challenges. Traditionally, the preloading of bearing system has been applied by uniform approaches such as rigid preload and constant preload. However, this treatment may hardly deal with the optimization of preloading problem due to the non-uniformity of the bearing stiffness becomes more apparent under high-speed operating conditions. A novel and practical approach is therefore presented in this paper to incorporate the non-uniformity effect to improve the structural performance of bearing under actual operating conditions. Firstly, the critical relationship between the stiffness behaviour and the non-uniform preload is evaluated for bearing system. The stiffness problem of angular contact ball bearing system is then formulated analytically by Jones’ model. With this approach, boundary conditions are achieved to solve the local contact deformation and predict the bearing life under non-uniform preload. Finally, both the uniform preload and the non-uniform preload cases for bearing system are simulated under various operating conditions. Comparing with traditional methods, the proposed method can provide a better solution in both stiffness and life that will enable a designer to obtain a deep insight on the optimization of bearing system.
Sintering of Chitosan and Chitosan Composites
Authors: Brysch Cynthia , Wold Eric , Robles Hernandez Francisco C. , Eberth John F.
Published: October 2013

Chitosan is a naturally-occurring polymer that is derived through the deacetylation of chitin. Chitin, found in the exoskeletons of invertebrates, is ubiquitous in nature and easily collected as waste and repurposed for a multitude of industrial and biomedical applications. Development of composites of chitosan and carbon are attractive due to their availability, compatibility, and mechanical properties. In the present work we construct a chitosan composite reinforced with 2 wt% carbon nanostructures using mechanical milling. The carbon nanostructures consist of amorphous carbon, graphene-like, and graphitic nanostructures synthesized by mechanical exfoliation. We demonstrate that the mechanical properties of this composite material can be altered by varying the sintering conditions. Preliminary thermal analysis showed a degradation temperature around 220 ± 5 °C but this was also influenced by the duration of temperature exposure. The material was strengthened by adding carbon nano-composites and through sintering. Better sintering conditions occurred at lower temperatures and shorter times. The new material properties are characterized by means of mechanical testing, electron microscopy, Raman spectroscopy, and X-ray diffraction.
Comparison of Two Approaches to Model Cure-Induced Microcracking in Three-Dimensional Woven Composites
Authors: Tsukrov Igor , Giovinazzo Michael , Vyshenska Kateryna , Bayraktar Harun , Goering Jon , Gross Todd
Published: October 2013

Finite element models of 3D woven composites are developed to predict possible microcracking of the matrix during curing. A specific ply-to-ply weave architecture for carbon fiber reinforced epoxy is chosen as a benchmark case. Two approaches to defining the geometry of reinforcement are considered. One is based on the nominal description of composite, and the second involves fabric mechanics simulations. Finite element models utilizing these approaches are used to calculate the overall elastic properties of the composite, and predict residual stresses due to resin curing. It is shown that for the same volume fraction of reinforcement, the difference in the predicted overall in-plane stiffness is on the order of 10%. Numerical model utilizing the fabric mechanics simulations predicts lower level of residual stresses due to curing, as compared to nominal geometry models.
The Absolute Evaluation and Loosening Life Prediction Method on Self-Loosening of Bolted Joints During Actual Machine Operation
Authors: Hareyama Soichi , Manabe Ken-ichi , Nakashima Makoto
Published: October 2013

This paper presents a method for estimating the absolute lock effect in bolted joints during actual machine operation.

The absolute evaluation on self-loosening is indispensable for the prediction of the life of locking devices (parts)/method at actual machine operation. The loosening phenomenon of bolted joint can be viewed as the decrease tendency of the initial axial tension or residual axial tension. According to the author’s previous report, there is a good linear relation on logarithmic coordinates (log-log paper) between the decrease of axial tension (measured tension/initial axial tension) and number of operations (or working time or mileage) since last tightening.

Based on this relation, and observation of loosening in the early stages of product development, we estimate the rate of axial tension decrease (degree of self-loosening) accurately after prolonged operation since tightening by measuring the initial axial tension behavior by using the proposed regression formula. The trial calculation of the residual axial tension after prolonged operation is made using the industrial vehicle (stacking capacity 16-ton large-sized forklift-truck) at customer’s site by loosening measurement. According to the estimation using only a few day’s data, it is presumed that initial axial tension is kept 55% or more in case of anaerobic adhesive tightening and almost 30% in case of lubrication tightening after ten years.

In the working load type loosening, authors propose the L-N diagram (Loosening Life - Numbers of Cycles to Loosening N Diagram) for loosening life estimation like the S-N diagram for fatigue life estimation. Using the loosening frequency diagram and L-N diagram, the degree of loosening damage for every axial tension’s residual ratio is figured out to analyze the loosening life of the locking device/method by Miner’s rule and cumulative loosening damage models.
Steady-State Analysis for Oxygen Diffusion in Infarcted Myocardial Tissue
Authors: Wang Bo , Chen Xiaolin
Published: October 2013

Myocardial infarction (MI), commonly known as a heart attack, can cause restriction in blood supply and oxygen shortage. The current stem cell therapy aims to rebuild lost myocardial tissue including its vasculature after MI. However, it should be determined how many vessels myocardial fibers need and how these vessels should be distributed to deliver enough oxygen to maintain their normal function. Mathematical modeling is a good approach to systematically determine the number and distributions of vessels that are needed. In this study, we employ Boundary Element Method combined with Fast Multipole Algorithm to predict the level of hypoxia after MI. Morphology of cardiac tissue based on available morphometric images is used for simulation. Steady state solutions for oxygen level distribution in both normal and infarcted heart are achieved. The numerical studies show that the developed FMBEM can effectively handle the diffusion process in the real world.
Mechanical and Thermal Properties of Jute-Glass Fiber Reinforced Nano Composites
Authors: Surya D. P. , Munirah A. M. , Alamelu S. S. , Lau J. C. H. , Wei J.
Published: October 2013

The rising concern towards environmental issues and lower production costs has led to increasing interests on the use of natural fibers to replace glass fibers as reinforcements. In this paper, the mechanical and physical properties of natural fiber composites and their hybrids or sandwiches were investigated. Jute woven fabric composites and their sandwiches were produced by applying vacuum assisted resin transfer molding (VARTM). For the composite sandwiches, glass woven composites were placed at the outer surfaces of jute woven composites and could act as strong skins. Therefore, the bending properties of jute-glass woven composites are higher than those of jute woven composites. The thin glass woven composites at the outer layer of composite sandwich also reduce the rate of water absorbed by the composites. The water absorption in jute-glass woven composites is lower than those in jute woven composites. Nano fillers that were added into the composites were expected to improve the mechanical and thermal properties of the composites. So far, matrices with 1 wt% of nano fillers have been successfully infused into fibers through VARTM process. The thermal properties of glass woven composites with nano fillers are significantly increased. However, the addition of nano fillers in jute fiber composites does not increase their thermal properties as the decomposition of the natural fiber occurs at the temperature whereby the epoxy matrix starts to degrade.
A New Design for Variable Diameter Orifice Mechanism
Authors: Gharib Mohamed
Published: October 2013

Variable diameter orifice is required in many applications e.g. smokestacks coal furnaces, liquid dispensing machines, wall fans, gas handling systems, pipes, vacuum chambers air valves, fluid control systems, ventilation systems, ducts, spot lights, holes of golf sports, photography nozzles, solid free fabrications and vacuum valves [1–17]. The need for variable diameter is to control the medium transfer through the orifice. In this abstract, a new design for a variable diameter orifice is introduced. Designing a variable diameter orifice is a challenging problem due to the need of circular geometry of the orifice opening. Many designs have been conducted to design a variable diameter orifice. However, the proposed designs are either have non circular opening or require a bulky size mechanism. In the proposed design, simplicity, size and actuation are our main concern.
The Effect of Inlet Flow Distortion on Performance of a Micro-Jet Engine: Part 2 — Engine Tests
Authors: Naseri A. , Boroomand M. , Tousi A. M. , Alihosseini A. R.
Published: October 2013

This paper concerns investigating effect of inlet flow distortion on performance of a micro-jet engine. An experimental study has been carried out to determine how the steady state inlet total-pressure distortion affects the performance of a micro gas turbine engine. An inlet simulator is designed and developed to produce and measure distortion patterns at the engine inlet. An Air Jet Distortion Generator is used to produce non-uniform flow patterns and total pressure probes are implemented to measure steady state total pressure distribution at the engine face. A set of wind tunnel tests has been performed to confirm the fidelity of distortion generator and measuring devices. The engine got exposed to inlet flow with 60-degree, 120-degree, and 180-degree circumferential distortion patterns with different distortion intensities and the engine performance have been measured and compared with that of clean inlet flow. Results indicate that engine performance can be affected significantly facing with intense inlet distortions.
Effects of High Shear Rate on Thrombus Formation Rate on Pipe Orifice Flows Using Laser Sheet Method and the Prediction of Thrombus Formation Rate by CFD
Authors: Tamagawa Masaaki
Published: October 2013

This paper describes visualization of thrombus formation process on orifice flows by laser sheet beam. The aim is to investigate the effects of shear stress or shear rate on the thrombus formation or thrombus formation rate. In this investigation, by visualization of the thrombus formation in blood plasma flow, it was found that the high shear rate region of the flow has large effects of the thrombus formation.
Weld Lining Strength of Injection Molded Jute/PLA and Jute/PP
Authors: Wang Cuntao , Yang Yuqiu , Urakami Masuo , Hamada Hiroyuki
Published: October 2013

Weld lines are formed inevitably when two separate melt fronts rejoin during injection molding. It has been reported that weld lines greatly weaken the strength of injection-molded parts. Therefore, in this paper the weld property of injection molded jute /PLA and jute/PP dumbbell shape specimen with weld line was investigated by changing pellets materials.

In the study pultrusion technique was adopted to fabricate jute/PLA and jute/PP long fiber pellets (LFT) and it was found that fiber bundles in LFT specimens were not separated and dispersed well. As a result, in this paper re-compound pellets of LFT, i.e. RP was made. Then LFT, RP, and hybrid mixtures with the hybrid ratios of LFT50:RP50 were used to mold dumbbell shape specimens with or without weld line. In particular, the influence of different pellets on weld line strength of injection molded jute/PLA and jute/PP dumbbell shape specimens with weld line was discussed based on tensile test and SEM observation.

It was found that tensile strength of RP specimens was higher than that of LFT both for jute/PLA and jute/PP, because fiber distribution and interfacial property of RP was much better than that of LFT. Weld line strength of RP was improved than that of LFT both for jute/PLA and jute/PP. RP of jute/PLA was more effective to improve the weld property than that of jute/PP. Weld line strength of jute/PP LFT increased as holding pressure increased from 44 to 88 MPa and decreased at 132 MPa holding pressure. It depends on the co-effect of fiber orientation and voids content.
The Effect of Inlet Flow Distortion on Performance of a Micro-Jet Engine: Part 1 — Development of an Inlet Simulator
Authors: Naseri A. , Boroomand M. , Tousi A. M.
Published: October 2013

This paper represents the development of an inlet simulator to produce and measure steady state total-pressure distortion at the inlet of a micro-jet engine. Different methods of distortion generation and engine testing are discussed and the developed system is described. The developed inlet simulator device consists of a direct connecting air supply duct, a distortion generator unit inside the duct ahead of the engine inlet, and a matrix of total pressure probes at the end of the duct and close to engine entry. An Air Jet Distortion Generator is designed and developed to produce desired distortion patterns at the engine face. A series of wind tunnel tests has been carried out to verify the ability of the system to simulate various inlet flow conditions. Circumferential patterns with 60, 120 and 180 degree distorted zones with different distortion intensities were produced during wind tunnel tests. Measured distortion patterns are represented and the proper operation of the system in wind tunnel is discussed and proved. The inlet simulator then get installed on a micro gas turbine engine and distortion patterns has been produced and measured at the engine inlet during engine performance tests. Measured patterns at the engine inlet and the engine responses are represented.
Numerical Investigation of Selective Laser Melting Process for 904L Stainless Steel
Authors: Fateri Miranda , Gebhardt Andreas , Khosravi Maziar
Published: October 2013

Selective Laser Melting process (SLM) is an important manufacturing method for producing complex geometries which allows for creation of full density parts with similar properties as the bulk material without extensive post processing. In SLM process, laser power, beam focus diameter, and scanning velocity must be precisely set based on the material properties in order to produce dense parts. In this study, Finite Element Analysis (FEA) method is employed in order to simulate and analyze a single layer of 904L Stainless Steel. A three-dimensional transient thermal model of the SLM process based on phase change enthalpy, irradiation scattering, and heat conductivity of powder is developed. The laser beam is modeled as a moving heat flux on the surface of the layer using a fine mesh which allows for a variation of the shape and distribution of the beam. In this manner, various Gaussian distributions are investigated and compared against single and multi-element heat flux sources. The melt pool and temperature distribution in the part are numerically investigated in order to determine the effects of varying laser intensity, scanning velocity as well as preheating temperature. The results of the simulation are verified by comparing the melt pool width as a function of power and velocity against the experimentally obtained results. Lastly, 3D objects are fabricated with a SLM 50 Desktop machine using the acquired optimized process parameters.
Experimental and Numerical Analysis of Ocular Tactile Tonometry
Authors: Enikov Eniko T. , Madarász Marcel , Polyvás Péter P.
Published: October 2013

This article describes the experimental and numerical analysis of a novel trans-scleral tonometer based on the use of an instrumented form of digital palpation tonometry. Similar to manual digital palpation tonometery (estimation of the eye pressure via tactile touch), the novel ocular tactile tonometer utilizes multiple force probes to gather force data from indentation experiments. The presented experimental and numerical analysis shows that force data obtained from these probes correlate with the intraocular pressure (IOP) of the eye. Enucleated porcine eyes were used to validate the approach. The observed hysteresis in the force data was analyzed using an analytical model that accounts for the outflow of the aqueous humor as well as experiments at different indentation rates. Experimental data from eye distention and indentation tests were then used to infer the conditions under which the novel tonometer would be expected to have an accuracy of 1 mmHg. Analysis of the data shows that visco-elastic behavior of the scleral tissue is the primary factor responsible for the observed hysteresis. Further analysis of the data shows that indentation rates should be kept below 0.5 mm/sec for a pressure range of 10–35 mmHg. A conceptual through-the-eye-lid ocular tactile tonometer based on four probes is also presented along with numerical validation of the measured response.
Mechanical Characterization of the Layer-Specific Human Aorta
Authors: Zhao Shijia , Gu Linxia , Lin Shengmao
Published: October 2013

In this work, three layers of human aorta, i.e. intima, media and adventitia, obtained from a 9 mm CryoValve® aortic valve allograft, were tested along both axial and circumferential directions. Preconditioning with a stretch ratio of 1.35 was used to mimic the physiological pulsatile loading conditions of the tissue. Results suggested that the stiffness along circumferential direction is generally larger than axial direction in each of the three layers. In all three layers, the media layer is the stiffest, and the adventitia layer is the softest regardless of testing directions. The anisotropic, nonlinear elastic mechanical behavior of each layer from the aortic valve allograft could help better understand the compliance mismatch between the allograft and native arterial tissue.
A Comparative Study of Tribological Behavior of Steel Sliding Against WC Under Mineral and Biodegradable Oil Lubrication
Authors: Darshan Anup , Paturi UmaMaheshwera Reddy , Suresh Kumar Reddy Narala , Regalla Srinivasa Prakash
Published: October 2013

Now a days for machining operations apart from good tribological properties, the lubricant is also expected to be non-hazardous and non-polluting. When considering the ecological and environmental aspects in machining processes, the use of biodegradable oil can be an alternative source of lubricant due to its positive impact to employee health and environmental pollution. In this regard, our research work uses vegetable based cutting fluids developed from canola and sunflower oil, in an attempt to provide an eco-friendly environment. Experiments are carried out on a pin-on-disc tribometer with tungsten carbide (WC) pin against AISI 4340 steel disc for different sliding times under different environments, thus simulating the machining environment. The tribological properties, wear and friction of vegetable based oils were comparatively investigated with a commercially available mineral oil. Wear tracks and roughness profiles of test specimens were compared by using optical microscope and profilometer respectively. Results indicated that vegetable based canola oil demonstrated excellent tribological properties compared to that of commercial mineral oil.
Fatigue Behavior of API X-80 Steels
Authors: Kwon Jaeki , Jeong Daeho , Choi Inkyun , Kim Youngju , Woo Namsub , Kim Sangshik
Published: October 2013

API X-80 steel is extensively used as a piping material in oil and gas industries with good combination of strength, toughness and resistance to H2S damage. Drill riser, for example, is a conduit providing a temporary extension of a subsea oil well to surface drilling facility and is in large part made of welded X-80 steel pipe. The riser system is subject to fatigue loading from wave and tidal motion, vortex induced vibration (VIV) and operating loads at low temperatures in corrosive environments. The reliability of drill riser system is extremely important and therefore the effects of environmental factors, including temperature and seawater, on fatigue crack propagation (FCP) behavior of X-80 steels, both BM (base metal) and WM (weld metal), need to be well understood. In this study, S-N fatigue and FCP tests were conducted on X-80 steel, including BM and WM, in air at 25 and −50°C and an R ratio of 0.1. The FCP tests were also performed on X-80 steel BM in artificial sea water at both cathodically and anodically controlled voltages. The fatigue behavior of X-80 steel at various testing conditions are discussed based on detailed optical micrographic and SEM fractographic observations.
Multi-Period Turning Interpolation Algorithm for High-Speed Machining of Continuous Line Segments With Limited Acceleration, Jerk and Chord Error
Authors: Zhang Lixian , Gao Xiao-shan , Li Hongbo
Published: October 2013

In this paper, a multi-period turning interpolation algorithm, with real-time look-ahead scheme based on S-curve control method, is presented. In this interpolation algorithm, the geometric precision and the dynamic performance are both satisfied. The machining efficiency is improved by multi-period turning transition, and the precision is also improved by S-curve control method. The computational efficiency of this algorithm meets the need of real-time machining. In addition, there is no accumulated error. At last, this algorithm is verified the validation by the experiments on 3-axis CNC machine.
Characterisation of Fatigue Crack Growth in Silicone for DEAP Technology
Authors: Thorup Thor
Published: October 2013

In this paper, the fatigue crack growth characteristics of Elastosil® RT 625 are determined by performing fatigue crack experiments based on ISO 27727. Elastosil® RT 625 is a silicone rubber used by Danfoss PolyPower A/S as the dielectric material in their DEAP elements.

Cracks were characterised by a large amount of crack tip roughening, and a crack pattern that oscillated around the mean crack propagation direction. The amount of deviation from the expected crack path was proportional to the strain-level in the test. Despite the rough oscillating crack appearance, a linear relationship between the crack length and the amount of cycles was obtained. When plotting the crack growth per cycle against the applied load, the existence of a power law domain which can be described by Paris’ Law was observed. The silicone rubber had a significantly lower β exponent than a large range of other rubbers.
Kinematic Analysis of Elbow and Scapula Based on Changes in Arm Support Length and Central Axis Location Through Rotational Motion of Upper Limb
Authors: Hong Jae Soo , Chun Keyoung Jin , Kim Jong Hyun , Hong Jung Hwa
Published: October 2013

An increase in the aging population around the world and in degenerative diseases has caused an epidemic of stroke. Hence, rehab equipment for treating its after-effects has been actively developed. A repeated upper-body rehab exercise is required and this exercise can only yield good results when its accurate motion is guided by a therapist. However, few kinematics studies have been conducted based on design variables such as changes in the rotational central axis and body measurement. So, this study analyzed the angular changes in two motions of the elbow (Flexion-Extension: F-E, Pronation-Supination: P-S) and three motions of the scapula (Anterior-Posterior tilt: A-P, Internal-External rotation: I-E, Upward-Downward rotation: U-D) based on changes in the arm support length and central axis location.

Eight healthy subjects participated in this study. Rehabilitation equipment for the upper limb, which can be adjusted to different arm support lengths and central axis locations, was used as the experimental equipment. The length could be adjusted to five levels (280 mm, 220 mm, 160 mm, 100 mm, and 40 mm). In the case of an experiment involving changes in the axis locations, the length was fixed as 280 mm, which allowed five different axis locations. Each subject implemented a rotational movement passively at an angular velocity of 30°/s.

In this study, we observed changes in the motion patterns of the upper-limb rotational movement based on the length and the location. The patterns based on the two design variables revealed a consistent tendency under the elbow (forearm) and the scapula (shoulder rhythm). Yet, three scapula motions showed little changes in the angular width, and only I-E showed an angular width of 5°. First, with respect to the tendency of the five motions based on changes in the lengths, the prolonged length showed a decreased angular width. Second, in terms of the tendency of the five motions based on changes in the locations, a relatively long distance between the handle and the axis (Location 1 → Location 5) confirmed a decreased angular width owing to a relatively small rotational movement at Location 5.

The F-E motion of the elbow clearly showed two time cycles per rotation. Other motions revealed one time cycle per rotation. With respect to the upper-body rotational movement, we confirmed that motions related to the forearm were more active than motions related to the shoulder.
An Object Transportation System Using Controlled Daphnia Magna
Authors: Itoh Akitoshi , Kawamata Masahiro , Hirai Tomohiro
Published: October 2013

In this study, we tried to create an object transportation system using Daphnia magna. We developed a target object for the transportation experiment using a 5-mm-diameter transparent acrylic rod with a hole in the lower part. Black film and a small white ball were attached to the top surface of the object in order to improve contrast and allow easier position detection during image processing.

The daphnia were first directed to the guide point, about 10 mm opposite the desired transportation direction. They were then guided to collide with the object. If a collision did not occur, they were guided to an evasion point 5 mm to the side of the object, then back to the guidance point and directed to collide with the object once again.

When the daphnia is making contact with the object, the guidance direction was compensated to the outside of the target course to transport along the target course. A compensation angle was calculated by the proportional control method.

By using this control scheme, daphnia could transport an object through the seven apices (about 1.5 laps) of the star-shaped target routes.
Generation of Optimized Robotic Assembly Sequence Using Immune Based Technique
Authors: Biswal Bibhuti Bhusan , Pattanayak Sujit Kumar , Mohapatra Rabindra Narayan , Parida Pramod Kumar , Jha Panchanand
Published: October 2013

Automated assembly using robots is being gainfully used to enhance the process capabilities in the manufacturing world because of the fact that it is faster, more efficient, precise and cost effective process than any conventional mechanized process. However in assembly operations it is essential to determine the assembly sequence that is feasible, stable and faster so that an economical process can be evolved. Since robotic system is a cost intensive one it is necessary to find out the correct and optimal sequence with the constraints of the process in mind while dealing with assembled products with large number of parts. One of the most critical situations is to detect the best assembly sequence for products having large number of different alternative solutions. In this paper, a new methodology has been developed to find out the best robotic assembly sequence among the feasible robotic sequences. The feasible robotic assembly sequences have been generated based on the assembly constraints and later, the Artificial Immune System (AIS) has been implemented to find out the best assembly sequence.
Experimental and Numerical Investigation on the Discharge of Wood Pellets From a Hopper With the Discrete Element Method
Authors: Höhner Dominik , Wirtz Siegmar , Scherer Viktor
Published: October 2013

In this study hopper discharge experiments with wood pellets were conducted. The experimental bulk density, flow behavior and discharge rate were compared to corresponding 3-dimensional discrete element simulations with both multi-sphere and polyhedral approximations of the pellet geometry. Additionally a numerical sensitivity analysis for the particle-wall friction was made in order to evaluate the influence of this parameter on hopper discharge in the context of different particle geometries.

In the past comparisons of experimentally and numerically obtained results demonstrated the adequacy of the discrete element method for predicting the general discharge behavior of a hopper. Nevertheless, in this study, comparing two different particle shape-approximations, significant differences in terms of bulk density, discharge rate, flow profile and dependency on the particle-wall friction coefficient between both investigated particle-shape approximation schemes could be observed. As a result, particle shape-representation must be considered a significant parameter in DEM-simulations.
The Effect of Surface Enhancement on Improving the Fatigue and Sour Service Performance of Downhole Tubular Components
Authors: Scheel Jeremy E. , Hornbach Douglas J.
Published: October 2013

Sulfide stress cracking (SSC) and hydrogen embrittlement (HE) prevent the use of high strength carbon steel alloys in the recovery of fossil fuels in H2S containing ‘sour’ environments commonly experienced in deep well fossil fuel recovery efforts. Couplings are a common weak point in casing strings as high magnitude mean tensile stresses are generated by connection interferences created during power make-up of downhole tubular components. When subject to service loads both mean and alternating stresses are increased further providing the high tensile stresses necessary for SSC initiation. Since high strength carbon steel alloys are not typically suited for sour service environments, the current solution is to use or develop much more expensive alloys with increased corrosion-cracking resistance, or limit their use to significantly weaker sour environments, or higher operating temperatures.

Failure due to fatigue is another major problem in downhole tubular components. Likelihood of fatigue failure is further exacerbated in corrosive environments (such as H2S and NaCl), commonly encountered in service. The cost for detecting the impending failure before final separation is dramatic at a factor 10X. A cost effective method of mitigating failure from SSC and corrosion fatigue would greatly reduce operational costs and extend component life.

Introduction of stable, high magnitude compressive residual stresses into less expensive carbon steel alloys alleviates the tensile stresses, and mitigates SSC, while also improving fatigue performance. Low plasticity burnishing (LPB) is an advanced surface enhancement process providing a means of introducing compressive residual stresses into metallic components for enhanced fatigue, damage tolerance, and SCC performance.

The effects of LPB on high cycle fatigue (HCF) and SSC were evaluated on quench and tempered API P110 grade steel. LPB processed specimens had an increase in fatigue life greater than an order of magnitude over untreated specimens. LPB was successful in completely mitigating SSC in all test specimens at tensile stresses up to 90% specified minimum yield strength (SMYS). The initial results indicate that LPB processing of P110 steel provides an economical means of SSC mitigation and fatigue strength improvement in sour environments.
Structural and Mechanical Multi-Scale Characterization of White New Zealand Rabbit Achilles Tendon
Authors: Kahn Cyril J. F. , Dumas Dominique , Arab-Tehrany Elmira , Marie Vanessa , Tran Nguyen , Wang Xiong , Cleymand Franck
Published: October 2013

Tendons and ligaments are complex multi-scale collageneous structures playing a fundamental role in mouvement. Even if these tissues are extensively studied in the past decades, modeling their non-linear viscoelastic properties is still a tough challenge. In order to reveal the relationship between the multi-scale structures and the macroscopic mechanical properties, we used atomic force microscopy (AFM) and second harmonic generation (SHG) microscopy to study unstreateched microtome slices of rabbit Achilles tendons, and an Adamel Lomargy DY.22 tensile test machine to study the dynamic properties of these tissues. Based on our data, a Zener model was used to describe the dynamic loading and unloading cycles.
Simulation Driven Processing Function Development, Offering and Operation
Authors: Karlberg Magnus , Löfstrand Magnus , Marjavaara Daniel , Lundström T. Staffan
Published: October 2013

In today’s industry, functional provision is becoming more and more important, necessitating increased simulation support. In this paper, the objective is to present a modeling and simulation approach for simulation-driven design (SDD) to support function development. The scope of this paper is simulation support for developing hardware equipment used in processing industry. The research is founded on industrial needs identified through two parallel interview-based studies in the Swedish process industry. Both companies explore doing business with functional products rather than hardware, in scenarios where the responsibility for and availability of the functions may remain with the service provider. One as-is and one future (to-be) scenario are presented. A decomposition of a general processing function (applicable to both companies) describes how the companies transfer machine input to output specifications. The decomposition includes customer and provider value and the paper demonstrates, as part of the results and based on the SDD approach, how that value may be increased through evaluation and prioritization. Additionally, the SDD approach shows that it is possible to identify a set of solutions which meet the specified requirements, supporting evaluation and prioritization of business offers and activities.
Design of Experiments for Aeroelastic Analysis
Authors: Smith Natasha , Camberos Jose , Alyanak Edward
Published: October 2013

The performance of an aircraft in flight is, in part, a result of interactions between aerodynamic forces and structural deformations. Aerodynamic pressures result in elastic deformations which alter the wing shape and thus affect the aerodynamics. Consideration of this multidisciplinary interaction is critical to wing design. In particular, divergence (static elastic instability) and flutter (dynamic resonance) are potential catastrophic effects to be avoided. Performing an aeroelastic analysis requires the combination of static and dynamic structural analysis (often done through finite element analysis) with aerodynamic analysis (typically using some form of computational fluid dynamics, CFD). For large grids, each of these can require a significant computational effort. Resolving the interactions between the two is an iterative process which only magnifies the problem. This is a typical characteristic and drawback of multidisciplinary analysis; it makes exploring a large design space (which may include a large range of wing shape, structural support, and material choices) particularly challenging.

Statistical design of experiments (DOX) is one technique for design space exploration using a limited number of targeted, computational experiments. DOX is useful for identifying the design variables most critical for a relevant response, and for finding sensitivities needed for design optimization. The objectives for this project were (1) to find the most significant geometric, modeling, and material parameters that affect the predicted aeroelastic responses of a simple wing geometry, (2) to develop parsimonious, low-order response surfaces to model effects of interest, (3) and to evaluate the quality of the response surfaces. The computational experiments were performed with MSC Nastran which combines finite element analysis for the structural response with a steady vortex-lattice method for trim aeroelastic analyses. The discussion will include an overview of the experiment design selection process, formulation of an approximation model, and an explanation of key metrics for evaluating the response surface designs. Comprehensive results are presented for the natural frequency responses, as well as a preliminary analysis of aerodynamic trim solutions.
Localizing Common Faults for Improved Aero Engine Maintenance
Authors: Walker R. B. , Perinpanayagam S. , Jennions I. K.
Published: October 2013

As industry moves towards implementing next generation Integrated Vehicle Health Management (IVHM) systems, the ability to quickly localize common faults in aero engines for improved maintenance is an important step in realizing this aim. Using a combination of high-fidelity finite element simulations and system level models, common unbalance faults have been studied for the purposes of localization. Looking at stationary and rotating vibration phenomena, features for fault localization have been identified and discussed from the perspective of implementation in future IVHM systems for rotating machinery. This includes studies into both the lower and the higher end of the frequency spectrum, looking at mode shapes, frequency response functions and forces at the bearing points in static conditions. Under rotating conditions, Campbell diagrams and transient analysis have been considered. In order to evaluate using the features identified, system level models have been created using Craig-Bampton reduction techniques, which are capable of recreating the studies conducted using the higher-fidelity finite element models. A discussion on introducing model based reasoning techniques to the system level model in order to adapt it for future IVHM systems are discussed. In turn, this leads to a discussion on a methodology for localizing faults in a wide range of rotating machines.
Acheon Project: A Novel Vectoring Jet Concept
Authors: Dumas Antonio , Pascoa Josè , Trancossi Michele , Tacchini Alessandro , Ilieva Galina , Madonia Mauro
Published: October 2013

This paper presents a general overview of the ACHEON Project (EU FP7 Level 0 - Transport including Aeronautic).

This project presents a novel dynamically controllable Coanda jet using two fluid streams to produce the angular deflection of the jet as a function of their momentum. A control system with electrostatic plasma is used to produce an effective and more precise control of the system.

This paper presents the general guidelines of the project which is going to start and presents expected results.
Estimation of Residual Stress in Spiral Welded Pipe: Regression and Numerical Model
Authors: Arif Abul Fazal M. , Al-Omari Ahmad S. , Sheikh Anwar K. , Al-Nassar Yagoub , Anis M.
Published: October 2013

Double submerged spiral-welded pipe (SWP) is used extensively throughout the world for large-diameter pipelines. Fabrication-induced residual stresses in spiral welded pipe have received increasing attention in gas, oil and petrochemical industry. Several studies reported in the literature verify the critical role of residual stresses in the failure of these pipes. Therefore, it is important that such stresses are accounted for in safety assessment procedures such as the British R6 and BS7910. This can be done only when detailed information on the residual stress distribution in the component is known. In industry, residual stresses in spiral welded pipe are measured experimentally by means of destructive techniques known as Ring Splitting Test. In this study, statistical analysis and linear-regression modeling were used to study the effect of several structural, material and welding parameters on ring splitting test opening for spiral welded pipes. The experimental results were employed to develop an appropriate regression equation, and to predict the residual stress on the spiral welded pipes. It was found that the developed regression equation explains 36.48% of the variability in the ring opening. In the second part, a 3-D finite element model is presented to perform coupled-field analysis of the welding of spiral pipe. Using this model, temperature as well as stress fields in the region of the weld edges is predicted.
Optimization of Assembly and Disassembly of GP7200 Engine
Authors: Sahay Chittaranjan , Shetty Devdas , Ghosh Suhash , Islam Mohammed , Turner Mark
Published: October 2013

Build studies were conducted on three different GP7200 engines at a local aircraft engine manufacturer to reduce cost while improving quality, reducing time (cycle time, takt time and lead time), reducing scrap, rework and reducing injuries (increased safety). The paper describes the development of an efficient and effective Dress and Strip process. This project incorporated standard concepts including, DIVE (Define, Investigate, Verify, Ensure), Takt time, Set-Up Reduction, 6S (Sort, Straighten, Shine, Standardize, Sustain and Safety), Kaizen, Quality control & Quality Information System (QIS) and Quality Clinic Process Charting program (QCPC). Seven Wastes (Overproduction, waiting for the next process, unnecessary transportation of materials, over processing of parts due to poor tool and product design, excess inventories, unnecessary movement, and defective parts from supplier), Standard Work, Total Productive Maintenance (TPM) and Value Stream Mapping (VSM) were used in the project. In addition, tools such as, Relentless Root Cause Analysis (RRCA), Root Cause Corrective Action (RCCA) and Mistake Proofing (MP) have been used in conjunction with other quality tools. Following the successful optimization of the process of assembly and disassembly of these engines, several recommendations were made including redesign of some assembly and disassembly tools. The paper presents an improved Assembly/ Disassembly spaghetti diagram and changes in tool design based on observations.
A Strategy for Generating Contoured Surface With Abrasive Waterjet Milling on Ductile Materials
Authors: Srikanth R. , Ramesh Babu N.
Published: October 2013

Surface generation by abrasive waterjet milling is one of the emerging applications of waterjet machining for processing of difficult to cut materials like super alloys, titanium alloys and hardened tool steels. The key aspect lies in the identification of certain important parameters that influence the kerf geometry and develop control strategies to produce easily reproducible kerfs and combine them together to produce a contoured surface. In this work, an attempt is made to devise control strategies, based on certain kinematic operating parameters like traverse rate, stand-off distance and impact angle of jet on the material, to generate a series of reproducible kerfs and to merge them together to produce a contoured surface. This is achieved by first discretely milling the surface into a series of kerfs separated by thin unmachined region and then gradually increasing the depth of these kerfs to match the requirements of the contoured surface with multiple traversal of jet. Subsequently these kerfs are merged by removing the regions separating them. The proposed control strategy is demonstrated by milling contoured surface on stainless steel 304 alloy. Finally, the efficiency of the proposed control strategy for producing contoured surface is assessed in terms of dimensional accuracy achieved on the milled surface.