bluuebunny/crossref_metadata_2025 huggingface dataset:
Micro UAVs Using Mechatronics Techniques
Authors: Shetty Devdas , Manzione Louis
Published: October 2013

This paper looks at the recent trends in mechatronic design configurations and examines how those approaches can be applied to the design of Micro Unmanned Aerial Vehicles. The current challenges in this area include the design of micro UAV systems that are capable of precise delivery, minimum volume and lower cost. This paper examines the use innovative techniques such as of axiomatic design, TRIZ (theory of inventive problem solving) and Hardware in the loop to arrive at a systematic design process. Virtual product design procedures involving simulation of complex systems allows designers to develop system without finalizing the hardware. The simulation procedure can be as “what if” scenario when the hardware doesn’t exist. Virtual simulations enable everyone to work on development before the first prototype is completed. Engineers can validate the entire operating cycle for the machine by driving the simulation with control system logic and timing. Given the small volume available when in launch configuration, the primary driving parameters were maximizing available wing area and relative wing effectiveness, while minimizing the required storage volume. The impact of G-forces on the structural viability, mechanical complexity and overall system survivability are important in determining the relative merit of the design concepts. This paper also addresses some of the practical applications, advantages and difficulties associated with the engineering applications of virtual reality.
Relative Effects of Cooling and Lubrication in Micro-Milling of Aluminum and the Design of Atomization Cooling and Lubrication Systems
Authors: Nevala Shawn E. , Wifvat Van T. , Johnson Samuel A. , Wentz John E.
Published: October 2013

Accelerated tool wear and tool breakage are significant problems in micro-machining processes such as micro-milling. Traditional flood cooling processes are unsuitable for micro-milling due to the excessive collision force between the fluid stream and the tool being large enough to affect the accuracy of the cutting process. In this research an atomization-based cooling and lubrication system is presented that delivers atomized cutting fluids to a micro-milling tool through the use of an original nozzle design based on two orthogonally-directed streams. The system and nozzle is used to investigate the relative importance of cooling and lubrication on micro-milling of 6061 T6 cold-rolled aluminum with a 0.508 mm diameter two-fluted end mill. Six cutting conditions are experimentally evaluated based on cutting forces and tool life. Lubrication is investigated through two concentrations (10% and 25%) of a semi-synthetic cutting fluid. Cooling is investigated through the use of atomized deionized water as well as dry cutting with cooling provided by a Ranque-Hilsch vortex tube. Dry cutting was used as a control. Statistical testing revealed the importance of lubrication relative to cooling when machining on the micro-scale as deionized water performed the worst of all tests conducted. Based on the experimental results, recommendations are made for the design of future micro-machining cooling and lubrication systems.
Modeling of Dynamic Delamination in L-Shaped Composite Brackets
Authors: Gözlüklü Burak , Çöker Demirkan
Published: October 2013

One of the widely used geometrically complex parts in recent civil passenger aircrafts is the L-shaped composite brackets connecting ribs to skins. Due to the sharp curved geometry, interlaminar opening stresses are induced and delamination occurs under considerable mode-mixities at the corner. Dynamic phenomena during delamination initiation and propagation of L-shaped beams are investigated using dynamic (explicit) finite element analysis in conjunction with cohesive zone methods (CZM). In ABAQUS a sequential explicit analysis followed by static (implicit) solution is used where the solution duration is considerably reduced. The thickness of the specimens is varied from 1.0 mm to 4.0 mm while the inner radius is kept same. Loading is applied parallel to one of the arms quasi-statically. Even though the crack is at the very middle of the specimen, this specific loading type yields variable traction fields and mode-mixities in the two sides of the crack in which delamination occurs under shear stress dominated loading on one crack tip and opening stress dominated loading on the other. It is observed that the delamination propagation is highly dynamic even though the loading is quasi-static. The speed of the delamination under shear dominated loading at one side can reach 800 m/s and under normal stress dominated loading is 50 m/s in dedicated thickness levels. In addition, moving elasto-dynamic radial compressive waves along the interface are observed. An important observation for design applications, a typical solution of adding more plies to the laminate might yield failure transition to a secondary crack nucleating at the arm and propagating towards the center crack.
Parallel High-Precision Orbit Propagation Using the Modified Picard-Chebyshev Method
Authors: Koblick Darin , Poole Mark , Shankar Praveen
Published: October 2013

The modified Picard-Chebyshev method, when run in parallel, is thought to be more accurate and faster than the most efficient sequential numerical integration techniques when applied to orbit propagation problems. Previous experiments have shown that the modified Picard-Chebyshev method can have up to an order of magnitude speedup over the 12th order Runge-Kutta-Nystrom method. For this study, the evaluation of the accuracy and computational time of the modified Picard-Chebyshev method, using the Java Astrodynamics Toolkit (JAT) high-precision force model, is conducted to assess its runtime performance. Simulation results of the modified Picard-Chebyshev method, implemented in MATLAB and the MATLAB Parallel Computing Toolbox, are compared against the most efficient first and second order Ordinary Differential Equation (ODE) solvers. A total of six processors were used to assess the runtime performance of the modified Picard-Chebyshev method. It was found that for all orbit propagation test cases, where the gravity model was simulated to be of higher degree and order (10 additional function calls to JAT using a 70 degree × 70 order Earth Gravity Model to increase computational overhead to 0.142 seconds per force function call), the modified Picard-Chebyshev method was faster, by as much as 100%, than the other ODE solvers which were tested.
Tracking Translations in the Human Hip
Authors: Zakani Sima , Smith Erin J. , Kunz Manuela , Wood Gavin C. A. , Rudan John , Ellis Randy E.
Published: October 2013

Translations of the femoral head with respect to the acetabular cup, in non-impinging zones, was investigated using surgical navigation methods. An ex-vivo study was conducted on five fresh-frozen human cadaver pelvises in distinct dissection states. Each specimen underwent a series of motions that included combinations of abduction/adduction, flexion/extension and internal/external rotations, repeated in four soft-tissue states: soft tissues intact; partially dissected with capsule intact; Z-shaped capsulotomy; and fully dissected and disarticulated. The data showed significant increases of excursions (p<0.05) between the first three soft tissue states. The findings supported the recently proposed model of aspherical hip motion, and imply that the femoral head translated before and after impingement. The results bring into question many accepted ideas in hip morphology, kinematics and surgical planning.
Improving Corrosion Fatigue and Damage Performance of 410 Stainless Steel via LPB
Authors: Hornbach Douglas J. , Scheel Jeremy E.
Published: October 2013

Stress corrosion cracking (SCC) and corrosion fatigue (CF) of 12% Cr stainless steel components can lead to reduced availability of steam turbines (ST). Significant operation and maintenance (O&M) costs are required to protect against CF and SCC in both aging and new higher efficiency ST systems. Shot peening has been used to reduce the overall operating tensile stresses, however corrosion pits, foreign object damage (FOD), and erosion can penetrate below the relatively shallow residual compression providing initiation sites for SCC and CF. A means of reliably introducing a deep layer of compressive residual stresses in critical ST components will greatly reduce O&M costs by improving CF life, increasing damage tolerance, reducing SCC susceptibility, and extending the service life of components.

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. LPB processing can be applied as a repair process during scheduled overhauls or on new production components.

High cycle fatigue tests were conducted on Type 410 stainless steel, a common alloy used in critical ST components, to compare the corrosion fatigue benefits of LPB to shot peening. Samples were tested in an active corrosion medium of 3.5% NaCl solution. Mechanical or accelerated corrosion damage was placed in test samples to simulate foreign object damage, pitting damage and water droplet erosion prior to testing. High cycle fatigue and residual stress results are shown. Compression from LPB was much deeper than the damage providing a nominal 100X improvement in fatigue life compared to the shallow compression from SP. Life extension from LPB offers significant O&M cost savings, improved reliability, and reduced outages for ST power generators.
Modular Product Design, Considering Functions and Properties
Authors: Aguilera Navarrete Israel , Lozano Guzmán Alejandro A.
Published: October 2013

In traditional machine, equipment and devices design, technical solutions are practically independent, thus increasing designs cost and complexity. Overcoming this situation has been tackled just using designers experience. In this work, a data clustering method which allows this data presentation in a more systematic way using a matrix arrangement, is shown. From this matrix, data can be reorganized in clusters with a hierarchical structure, in such a way that modular design is now more tractable. Proposed method is based on a Euclidean algorithm which allows finding the shortest vectorial distance among technical solutions. Taking product properties as vector dimensions, a recursive method for moving matrix rows and columns is applied. As a result of this procedure, the minimum vector distances are found thus being possible to identify the best technical solutions for the design problem raised. The proposed modular procedure is shown with a 30 inches oven door design.
Thermal Shock Effects on Dynamic Deformation Mechanisms in Ti2AlC
Authors: Bhattacharya R. , Goulbourne N. C.
Published: October 2013

The present study is aimed at understanding the effects of thermal shock and associated microstructural features on the dynamic deformation mechanisms in Ti2AlC, a Mn+1AXn phase ternary ceramic. These materials crystallize in a Hexagonal Close Packed (HCP) structure with a c/a ratio greater than 1.67 which results in kink band formations when subjected to loading. In this work, we report the microstructural changes associated with thermal shocking of Mn+1AXn phases and its effects on deformation mechanisms, under dynamic compressive loading. The specimens are heated to temperatures of 220, 550 and 900°C, held at each temperature for 5–10 minutes, and subsequently quenched in water at 20°C to induce thermal shock. The thermal shock resistance and its effect on mechanical properties is investigated by subjecting heat treated specimens to compressive loading at high strain rates (∼1000–4500 s−1) using a Split Hopkinson Pressure Bar (SHPB). The microstructures of thermally shocked specimens are characterized by Scanning Electron Microscopy (SEM) combined with Energy Dispersive Spectroscopy (EDS) analysis to reveal the surface morphologies and characteristics. The displacements during the deformation events are captured using in situ high speed imaging, with full-field 2D Digital Image Correlation (DIC) technique. The key microscale mechanisms of deformation are studied using SEM analysis of deformed/fractured specimens.
Study of Air Flow Into Ballistic Wounds Using Flow Visualization Experiments and Numerical Simulations
Authors: Hinz Brandon J. , Muci-Küchler Karim H.
Published: October 2013

A common type of battlefield injury involves high speed fragments of different sizes and shapes hitting the human body, particularly the extremities. Gaining a better understanding of the mechanisms involved in those injuries can result in better strategies for providing medical care. One aspect that still requires additional research is the contamination of ballistic wounds. Studies published in the open literature have shown that in perforating projectile wounds airborne debris such as skin, cloth, and soil particles are introduced into the wound by either the projectile or by the suction created due to the formation of the temporary wound cavity. These debris can transport bacteria resulting in infection, delayed wound healing, or other complications. The amount of suction and ultimately the bacteria distribution in ballistic wounds can vary depending on parameters such as projectile velocity, caliber, mass, and location of injury. Numerical models can be used to study the influence of various parameters on the suction effect but experimental data is needed to validate the simulation results.

This paper presents an experiment developed to provide an initial evaluation of numerical models of the air flow and suction effect in perforating projectile wounds. The experiment used rectangular prism (cuboid) targets made of ballistic gelatin which is a common soft-tissue surrogate material used in ballistic research. These targets were shot with 11.43 mm (0.45 in) caliber round lead projectiles fired from air rifles at approximately 230 m/s. The air flow into the temporary cavity of the tissue surrogate targets was visualized using a vapor curtain placed at the projectile entry location. A high speed digital camera captured the movement of the vapor curtain and the formation of the temporary wound cavity during the tests. To simulate the experiment, a Coupled Eulerian-Lagrangian (CEL) model was run using Abaqus/Explicit. In the model, the mechanical behavior of the soft-tissue surrogate target was represented using a hyper-elastic constitutive relation. A small pre-made cylindrical channel was added to the targets to avoid using techniques such as element erosion or considering material failure when modeling the passage of the projectile through the material. Qualitative and limited quantitative results from the model were compared with the results from the laboratory tests.
Risk of Clavicle Fracture Following Coracoclavicular Ligament Reconstruction for High Grade Acromioclavicular Joint Dislocations
Authors: Gustafson Peter A. , Omwansa Mark , Geeslin Andrew G. , Sabesan Vani J.
Published: October 2013

Finite element models are used for qualitative comparison of the risk of fracture associated with clavicle tunnels in reconstruction of the coracoclavicular ligaments for treatment of high-grade acromioclavicular joint (ACJ) injury. The two-tunnel reconstruction technique is found likely to have higher fracture risk than the less anatomic single tunnel reconstruction. The models suggest that four point bending is more likely than three point bending, cantilever bending, or axial loading to differentiate the reconstruction techniques in a laboratory experiment. The results must be narrowly interpreted only in a laboratory context due to the limitations of the study.
Anti-Evisceration Rings: Proof of Concept
Authors: Barnett Ralph L.
Published: October 2013

Domed suction entrapment covers (grates) are generally mounted on cylindrical sumps or frames (mud rings) that are permanently installed in the bottoms or sidewalls of swimming or wading pools. These covers constitute a first-line-of-defense against the danger of evisceration by preventing children from sealing the sumps and drains with their buttock. When the covers are missing, loose, or broken, sealing a sump with their backsides exposes their bowels to dangerous levels of suction that cause disembowelment in a fraction of a second. There is an emerging paradigm shift in the aquatic’s industry that calls for equivalent protection for covered and uncovered sumps and frames. Using a simple concept patented by Barnett (2001) [1], the planar circle formed by the inside edge of a sump is replaced by a non-planar edge, e.g., scalloped or castellated. Edge geometry is chosen that will not conform to human body parts to preclude sealing. Testing inexpensive prototypes demonstrated that the proposed anti-evisceration rings reduce the body removal force from 324 lb. to 10 to 17 lb. Further, they lower the maximum pump vacuum from −14.3 psi to −1 to −2 psi.
Standard Chain Lever Load Binder
Authors: Barnett Ralph L. , Liber Theodore
Published: October 2013

The standard chain lever load binder that is used for truck cargo securement operates on an over-center principle that has been used for over a century on suitcases, tool boxes and camera cases. The safety hazards associated with the uses and misuses of the load binder were identified decades ago and various inventors patented innovations that eliminated or mitigated the safety shortcomings. Furthermore, their ideas were not only effective, they were economical, versatile, and efficient. These patents are now in the public domain and many companies manufacture and/or distribute entire lines of securement that include not only the standard chain lever load binder but most of the alternative designs as well. This case study takes the position that the standard chain lever load binder should be banished. Since the appropriate bodies, after all these years, have not arranged for its demise, this paper appeals to the product liability system for safety relief. Engineering analysis and tests are provided to the legal profession to help them protect us by making the cost advantage of the standard binder too expensive. This paper explores some of the remarkable properties of the standard load binder, e.g.,

• Load binders develop very large chain tensions and very high levels of recoverable energy. The standard chain lever load binder does not enable the tension and energy levels to be safely maintained or released.

• The handle slack on the standard load binder cannot be fine-tuned; consequently, a scenario is frequently encountered where the chain is either too loose or too tight to secure with the binder handle. This is the major motivation for resorting to a “cheater bar.”

• A complete analysis of the securement forces acting on the cargo and load binder is seldom possible because the system is a “moving target.” The handle loading is randomly applied by human exertion which changes with handle orientation. The boundary conditions depend not only on the cargo and securement strategy, but on the loading itself. Unknown friction characteristics of the loading affect the distribution of chain forces.

• On one side of the load binder the chain tension can always be predicted using only the handle torque. This cable tension is independent of the boundary conditions and any axial handle force components.

• When the load binder system is rigid, it gives rise to three singularities. The mechanical advantage is unbounded at the two extreme handle orientations. When the binder is suspended in a taut condition, any lateral force on the binder develops infinite cable forces.

• Handle slack has a profound effect on the handle resistance, the resilience, the chain tension, and the latching capability.
The Effects of T4 and T6 Heat Treatment on the Corrosion Behavior of MgZnCa Alloys
Authors: Smith Christopher , Xu Zhigang , Sankar Jagannathan
Published: October 2013

Some of the most important characteristics of a medical implant biomaterial are its corrosion resistance, cytotoxicity, mechanical property, and overall biological performance. Optimizing these characteristics is therefore vital to the success of creating effective medical biomaterials. It is well known that heat treatment processes affect the microstructure of metallic alloys which consequently can have favorable influences on the mechanical properties. The determination of the effects of heat treatment on the corrosion resistance of metallic alloys is another aspect that must be examined. That is the goal of this investigation. The corrosion characteristics of two MgZnCa alloy systems (MgZnCa-31 and MgZnCa-32) were studied to determine the correlation between T4 and T6 heat treatment and the corrosion rate on the alloys. The alloys were produced by melting and casting at 730°C and then heat treated. The corrosion performances of the alloys were examined by both immersion and electrochemical analysis, which were conduct in 0.9% NaCl physiological saline solution. In terms of the effects of the T4 heat treatment, the corrosion rate of the MgZnCa-31 decreases as the time period of the heat treatment increases, whereas the MgZnCa-32 alloys have an opposite effect meaning that the corrosion rate increases as the time period of the heat treatment increases. There was no significant change in corrosion with the introduction of T6 heat treatment to both alloy systems.
Automated Recharging Station for Swarm of Unmanned Aerial Vehicles
Authors: Leonard Jeremie , Aldhaher Samer , Savvaris Al , Tsourdos Antonios
Published: October 2013

Automated maintenance has become a necessity for UAV systems to allow human operators to concentrate on higher-level tasks. By reducing the need for a human interaction, such systems could be set to function in remote environments for an extended period of time and take care of a higher number of vehicles. This paper describes the work carried out to design, test and construct an autonomous charging station for battery-powered quadrotors. In the effort to fit swarm behaviors, the focus has been to shorten the charging phase of a single quadrotor platform. By designing safer electrical contacts and adding a cell balancer to the system, the station can supply considerably more current to charge the vehicle’s battery. Once the vehicle has landed, voltage and current probes transmit the current state-of-charge to a controller for optimum charging cycle. To support even more applications, the system was equipped with the capability of wireless power transfer. Energy is transferred from a power transmitter in the docking station to a power receiver on-board the vehicle based on resonant inductive coupling. Minimizing the internal losses of the DC/AC inverter and AC/DC rectifier in the transmitter and receiver will allow for higher power levels to be transmitted and will maximize the efficiency.

With the continuous monitoring of the process and the advanced charging technologies allowing for a balanced high-current charge, the Flying/Charging ratio of the vehicle could reach 1.
Additive Manufacturing: Exploration of Porosity and Form Features Using Layer by Layer Deposition
Authors: Shetty Devdas , Ly Daniel
Published: October 2013

Aerospace companies use high-strength metal alloys like Inconel or Titanium which could be very difficult to fabricate using conventional methods. The current manufacturing techniques result in significant waste. Additive Manufacturing (AM), in its current state is not sufficiently understood, nor characterized such that conventional design practices and process qualification methodologies can be used. In addition, AM cannot be considered for the manufacture of aircraft components unless the process is stable and controlled. The mechanical properties of fabricated parts require to be characterized to demonstrate their invariability. The laser deposition using complex geometries is a challenge. In addition, the structural performances of AM parts have to be proved. Inherent in these requirements is the need to develop a process specification which requires the monitoring and control of key raw materials, consumables, and process parameters; the development of a fixed practice for each of the AM process. Several procedures are required in order to understand how additive manufacturing works using advanced and complex design models. The ability to adopt AM to the production of components is not only predicated on the ability of AM to be competitive with conventional manufacturing methods in terms of cost, but also on its ability to deliver parts with repeatable mechanical performance. The objective of this paper is to define and characterize the limitation of various complex geometries using additive manufacturing. The experimental research involved the creation of a number of specimens using direct metal laser sintering process, examination of their form features, documenting DMLS geometry limits for the form features and finally the creation of calibration models that can be used in aerospace design manuals.
Methods to Determine the Critical Damage Criterion of the Kachanov-Rabotnov Law
Authors: Stewart Calvin M. , Gordon Ali P.
Published: October 2013

Considerable effort has gone towards the implementation of continuum damage mechanics (CDM) laws for the creep damage assessment of high temperature components. Often critical damage is considered to be reached when damage is equal to unity. Analytical methods have demonstrated that for various alloys critical damage is much less than unity and is dependent on stress and temperature. Few studies have been conducted to evaluate and correct this problem. In this paper, an examination of the theory of critical damage is conducted. Based on theory, a new critical damage criterion is introduced. A comparison between Penny and the new critical damage criterion will be conducted to determine the most viable criterion. Damage is introduced into life, strain, and mixed life fraction rules to demonstrate the influence damage has on rupture under thermo-mechanical loading.
Evaluation, Optimization, and Verification of the Wrist Mechanism of a New Cooperatively Controlled Bimanual ENT Microsurgery Robot
Authors: He Chao , Olds Kevin , Akst Lee M. , Ishii Masaru , Chien Wade W. , Iordachita Iulian , Taylor Russell
Published: October 2013

This paper reports the evaluation, optimization, and verification of five different design proposals for the wrist system of a new microsurgery robot. The robot targets three main types of Ear Nose and Throat (ENT) surgeries. These surgeries require a compact design and configuration synthesis to decrease collisions, provide high precision and stiffness, and accommodate the clinical requirements of each surgery type. The system is composed of two 6 DOF active robots, each composed of a 3 DOF linear stage and a 3 DOF rotary wrist mechanism. The linear stage uses a 3 DOF parallel design to increase the accuracy and stiffness of the whole system while minimizing size and weight. However, to remain compact, this parallel mechanism introduces the problem of limited linear range of motion.

Five different kinematic arrangements have been considered, and the evaluation and optimization of these configurations is discussed in detail. The main parameters considered in the evaluation include the range of motion of each DOF, the required linear movement to implement a virtual remote center of motion (RCM), and the environment occupation near the surgical tool. The optimal design of the wrist mechanism was determined by evaluating each design with respect to these parameters, and comparing the results.

A prototype of the resulting optimal kinematic arrangement was mounted on a 3 DOF linear robot to verify the results of this optimization process. A series of verification experiments was performed. These experiments successfully verified the validity of the selected design.
Crash Energy Management of Rotorcraft Seat Based on Limit Load Curves and Corresponding Occupant Pelvic Load
Authors: Moradi Rasoul , Bromwell Tony , Jategaonkar Rohit , Lankarani Hamid M.
Published: October 2013

In military aircraft and helicopter seat design, the seat system must be provided with an energy absorber (EA) to attenuate the acceleration level sustained by the occupants. Because of the limited stroke available for the seat structure, the design of the energy absorber becomes a trade-off problem between the seat stroke and the impact energy absorption. The available stroke must be used to prevent bottoming out of the seat, and also to absorb as much impact energy as possible to protect the occupant. In this study, the energy absorbing systems in civil and military aircraft seat design are evaluated and improved using a mathematical model of the occupant/seat system. Three load-limit design curves, namely, simple EA, two-stage EA, and two-stage EA with initial spike, are modeled, examined, and compared. A model of the load limiter is recommended to minimize the load sustained by the occupant by limiting the relative velocity between the seat pan and the occupant pelvis. Experimental responses of seat system and occupant from literature are utilized to validate the results from this study for civil and military helicopters. A modified energy-absorber/load-limiter is then implemented for the seat structure so that it absorbs the impact energy in an effective manner below the tolerable limit for the occupant and within a minimum stroke. Results from this study indicate that for a designed stroke, the occupant pelvic/lumbar spine injury level is significantly attenuated using the modified energy-absorber system.
Simulations of Thermo-Mechanical Characteristics in Electron Beam Additive Manufacturing
Authors: Shen Ninggang , Chou Kevin
Published: October 2013

In the direct digital metal manufacturing, Electron Beam Additive Manufacturing (EBAM) has been used to fabricate sophisticated metallic parts, in a layer by layer fashion, by sintering and/or melting metal powders. In principle, EBAM utilizes a high-energy electron beam to melt and fuse metal powders to build solid parts with various materials, such as Ti-6Al-4V which is very difficult to fabricate using conventional processes. EBAM is one of a few Additive Manufacturing (AM) technologies capable of making full-density metallic parts and has drastically extended AM applications.

The heat transfer analysis has been conducted in a simple case of a single-scan path with the effect of powder porosity investigated. In the actual EBAM process, the scan pattern is typically alternate raster. In this study, a coupled thermo-mechanical finite element model was developed to simulate the transient heat transfer, part residual stresses of alternate raster during the EBAM process subject to a moving heat source with a Gaussian volumetric distribution. The developed model was first examined against literature data. The coupled mechanical simulation is able to capture the evolution of the part residual stresses in EBAM.
Reconstruction and Analysis of Human Walking Patterns Using a Computer 3D Vision System
Authors: Arellano-González Juan C. , Medellín-Castillo Hugo I. , Cárdenas-Galindo J. Antonio
Published: October 2013

Human walking analysis is an important research area of biomedical engineering since it provides accurate information for medical rehabilitation procedures and design of rehabilitation equipment, medical diagnosis and orthopedics, pathological and aging evaluation, design of human prosthesis, and design of humanoid robots. In some applications, such as the design of prosthesis and rehabilitation systems in biomedical engineering, and equipment design and performance analysis in sports engineering, human walking reconstruction under several conditions is required in order to optimize the design. Human walking process is smooth and efficient but it varies from one person to another depending on age, height, gender, weight, health condition, and walking conditions. Most of the research work in the literature has been focused on the analysis of gait patterns of healthy and unhealthy people under normal walking conditions, and they use 2D reconstruction of human walking trajectories.

The aim of this paper is to reconstruct and analyse human walking patterns of normal young adults under different gait conditions. A computer vision system to reconstruct 3D human walking trajectories is developed and presented in this paper. Several experiments with young adults walking under several conditions such as carrying a front load, carrying a lateral load, ascending, etc., are conducted. The results of these experiments have shown that human walking patterns vary according to the walking condition and therefore these variations should be considered in the design of prosthesis or rehabilitation systems.
Evaluation of Backstitch Tool Path Strategy for Stability and Productivity in Micro-Drilling
Authors: Moon Jong-Seol , Yoon Hae-Sung , Lee Gyu-Bong , Ahn Sung-Hoon
Published: October 2013

Micro-drilling with spacing intervals in the hundred micrometer range is an essential process, however suitable methods are lacking despite efforts to develop useful strategies for precision micro-drilling. For efficiency, printed circuit boards are stacked in several layers and drilled through simultaneously but the process results in misalignment of holes as observed between consecutive layers from top to bottom. The work herein proposes a new tool path strategy in comparison with conventional methods. Hole positioning, drilling thrust force, and duration time were measured and evaluated. This strategy can be utilized in micro-manufacturing process for improving machining stability and productivity.
A Novel Error Detection and Compensation Method of Hourglass Worm Gear Hob
Authors: Shu Q. Y. , Qiu Q. Y. , Feng P. E. , Cao L.
Published: October 2013

The double enveloping hourglass worm gear pair is a type of transmission, which has many traits, such as more teeth in mesh for transmission, higher contact quality, better lubrication condition and so on. Therefore, it has higher efficiency of transmission, stronger bearing capacity and longer work life. But the manufacturing difficulty of the worm gear hob has limited its popularization and application. Unlike the traditional worm gear hob which can use the principle of optical projection to detect the hob shaft section and compare with its mathematical model, currently, there is no standard mathematical model to detect the shaft section of hourglass worm gear hob. Hence, the accuracy of hourglass worm gear hob can’t be guaranteed during manufacturing process, and the accuracy of hourglass worm gear can’t be guaranteed too. Thus, the transmission performance of the manufactured double enveloping hourglass worm gear pair will be affected. The paper puts forward a novel detection method for hourglass worm gear hob on the basis of the detecting method for traditional worm gear hob and established the mathematical model of the shaft section of hourglass worm gear hob. The manufacturing error of hourglass worm gear hob can be obtained through such detection. The paper also points out that the error is mainly produced during the grinding of hob teeth, because the grinding wheel is worn out and the blank hob is thermally deformed. At last, a method for error compensation is advanced during the process of hob grinding. The paper presents a test to verify the feasibility of this method and the test result shows that the manufacturing error of hourglass worm gear hob is reduced from 30.15μm to 10.3μm.
Nonlinear FEA Simulation of Thorax Considering Transient CPR and Lateral Forces
Authors: Awad Omar , Al-Smadi Yahia M.
Published: October 2013

Boxing or martial arts are games where players chests are subject to lateral impact, the impact loads travel through skin, ribs, mediastinum (i.e. a thoracic compartment) and then through the skeleton to the rest of the body. When thorax is subject to lateral force exceeding the elastic limit of thoracic compartment, players often go in shock demanding prompt resuscitation. This paper investigates the thorax response of boxer being subject to lateral impact followed by Cardiopulmonary resuscitation (CPR). Due to complexity of thorax structure and materials, three dimensional finite element model in ANSYS was created to perform the computational biomechanical analysis of two-stage loading (i.e. lateral impact load and CPR forces). Model input parameters such as material, loading and boundary conditions have been defined. Post processing values such as deformations and stresses have been presented.
Aerodynamic Shape Optimization Using Improved Territorial Particle Swarm Algorithm
Authors: Nejat Amir , Mirzabeygi Pooya , Shariat-Panahi Masoud
Published: October 2013

In this paper, a new robust optimization technique with the ability of solving single and multi-objective constrained design optimization problems in aerodynamics is presented. This new technique is an improved Territorial Particle Swarm Optimization (TPSO) algorithm in which diversity is actively preserved by avoiding overcrowded clusters of particles and encouraging broader exploration. Adaptively varying “territories” are formed around promising individuals to prevent many of the lesser individuals from premature clustering and encouraged them to explore new neighborhoods based on a hybrid self-social metric. Also, a new social interaction scheme is introduced which guided particles towards the weighted average of their “elite” neighbors’ best found positions instead of their own personal bests which in turn helps the particles to exploit the candidate local optima more effectively. The TPSO algorithm is developed to take into account multiple objective functions using a Pareto-Based approach. The non-dominated solutions found by swarm are stored in an external archive and nearest neighbor density estimator method is used to select a leader for the individual particles in the swarm. Efficiency and robustness of the proposed algorithm is demonstrated using multiple traditional and newly-composed optimization benchmark functions and aerodynamic design problems. In final airfoil design obtained from the Multi Objective Territorial Particle Swarm Optimization algorithm, separation point is delayed to make the airfoil less susceptible to stall in high angle of attack conditions. The optimized airfoil also reveals an evident improvement over the test case airfoil across all objective functions presented.
Mechanical Wheelchair Propulsion System for Patients With Arthrogryposis
Authors: Garza Allison N. , Song Joseph L. , Gogola Gloria R. , Saterbak Ann , Wettergreen Matthew A. , Houchens Brent C.
Published: October 2013

Arthrogryposis is a congenital disorder characterized by extreme joint stiffness that inhibits strength and flexibility in upper and lower extremities. Cases vary in severity, but this research focuses on those in which patients require a wheelchair for mobility. Currently, two conventional designs exist: mechanical and electric wheelchairs. For most arthrogryposis patients, existing mechanical wheelchairs are insufficient for independent propulsion as their joints are severely impaired, prohibiting them from reaching the outer handrails on the wheels and expending enough force to propel and steer. Existing devices that improve the mechanical advantage of wheelchairs are insufficient for the needs of these patients who have very limited and specific ranges of motions, which are not compatible with the required force inputs. Though electric wheelchairs allow independent mobility, they are expensive to maintain and not easily portable, limiting their use by socioeconomically disadvantaged patients.

Arthrogryposis patients require a lightweight, portable and durable mechanical wheelchair that takes advantage of the user’s specific strengths, and is easily maneuvered in all directions without assistance. A design is presented for a socioeconomically disadvantaged teenage client with arthrogryposis. After taking data regarding the ranges of motion and strength of the client, a new propulsion system was designed and retrofitted to a conventional wheelchair. Prototye I has been tested and a second-generation design which fits the needs of a wider audience suffering from arthrogryposis is presented.
Implementation of Lean Tools and Methodologies in Design
Authors: El-Sayed Mohamed E. M.
Published: October 2013

Research efforts in lean design are usually focused on enabling lean manufacturing or managing the product development processes. Very few efforts, however, have been directed towards the design process itself. While the most successful lean applications started with the manufacturing process, due to its nature and the ability to identify the process wastes, the full impact of lean thinking can only be achieved when applied at the beginning of the product development process starting with early design phases. Considering that the first and most fundamental principle in lean thinking is to realize value from the customer’s perspective, it is essential that a lean product development process implementation assures the flow of this value throughout the process. This can only be accomplished when lean principles, tools, and methodologies are utilized in all phases from concept development in the design phase to manufacturing in the production phase.

In this paper, the utilization of lean principles, tools, and methodologies during the design process is discussed. In addition, the adaptation of several lean tools and methodologies to assist in applying the lean principles throughout the different phases of the design process is demonstrated. To illustrate the concepts, adaptation process, and implementation some examples are presented.
Expansion of Indicial Function Approximations for 2-D Subsonic Compressible Aerodynamic Loads
Authors: Farsadi T. , Javanshir J.
Published: October 2013

This article deals with the new generation of proper Mach dependent exponential approximations of the indicial aerodynamic functions toward the aeroelastic formulation of 2-D lifting surface in the subsonic compressible flow. The indicial lift response is a useful starting point in the development of a general time-domain unsteady aerodynamic theory. By definition, an indicial function is the response to a disturbance that is applied instantaneously at time zero and held constant thereafter; that is a disturbance given by a step function. If the indicial response is known, then the unsteady loads to arbitrary changes in angle of attack can be obtained through the superposition of indicial responses using Duhamel’s integral. The indicial functions have been used to modify the circulatory part of the lifting force and pitching moment in unsteady compressible aerodynamic models. The coefficients of the approximation are obtained with an indirect approach by relating numerical results obtained for oscillating airfoil in the frequency domain back into the time domain. compressible and supersonic flight speed regimes. Exponential approximations of the subsonic compressible indicial functions in the existing research works are available only in limited Mach numbers (M = 0.5, 0.6, 0.7, 0.8). In the present study, a novel exponential approximation is developed which represent the coefficients of approximations as functions of Mach number (0.5 < M < 0.8).
Design and Developement of a Microjet Engine Indoor Test Cell
Authors: Alihosseini A. R. , Boroomand M. , Tousi A. M. , Horoufi A.
Published: October 2013

Following design and construction of a prototype of an engine such as a microjet engine, the engine is placed in a test cell, and is tested by special instruments until the desired engine performance is achieved. The aim is to determine all of the engine components’ performance parameters. Successful testing, acquiring the right data and subsequent processing and analysis can be useful and effective in design, optimization and maintenance of such engines. This paper describes the process of design and construction of microjet engine indoor test cell at Amirkabir University of Technology and performance testing of a microjet engine. This project has been conducted after testing the engine at outdoor test cell. The fact of bringing the engine in an enclosed test bed has effects on engine’s performance especially on the engine’s thrust. Therefore, the aerodynamic design of the test cell is conducted in a way to provide uniform airflow for the engine, have less proneness to test cell influence factors and reduces the adverse environmental conditions on engine’s performance during the process of testing. The phase of construction of the indoor test cell followed after designing phase is presented. On the other hand, the choice of instrumentation and the way it is arranged is discussed. Finally, the process of testing the engine and gathering data is described and results from the first tests conducted on the finished facility are presented.
Evaluation Method for Mechanical Properties of Polymeric Brush as Cushioning Material on Conveying Equipment
Authors: Fukami Yasuhiko , Nishimoto Hiroyuki , Ohtani Akio , Nakai Asami , Hamada Hiroyuki
Published: October 2013

A steal bearing unit on conveying equipment in a turret punch press basically has noise problems. One of the solutions is a usage of polymeric brush instead of steal bearing, which works as the cushioning material. However, the loading characteristic is not clear because the concrete evaluation method for polymeric brush is not established. The variation on the head of each fiber in the brush makes the deviation in terms of the mechanical properties. Besides, our expectation to the heavy load is increasing in recent years. Therefore, the purpose of this study is to propose new method to evaluate the mechanical properties of the polymeric brush. Basically, the start point of stress increase on each fiber varies because of the different length of fibers on one brush. It makes difficulty on zero point adjustment according to each brush with different properties. Then we developed new zero point adjustment based on comparing with preloading and unloading characteristics. The experimental results show the validation that new evaluation method improves the predictive accuracy and imply more efficient designing in the conveyer equipment.
Wear Behavior of TiNi and TiNi-TiC Clads Deposited by TIG Surfacing Process
Authors: Harooni Masoud , Shamanian Morteza , Tehrani Alireza Fadaei
Published: October 2013

This paper deals with the investigation of wear behavior of TiNi and TiNi-TiC clads applied to plain carbon steel by tungsten inert gas (TIG) surfacing process. In this regard, ball milled Ti-Ni and Ti-Ni-C powder mixtures were used as feedstock materials. The clad layers were investigated using X-ray diffractometery (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), hardness measurements and reciprocating wear tests. The results of microhardness measurements indicated that hardness values of TiNi-TiC composites were higher than those of TiNi by approximately 100HV. It was also shown that the wear behavior of TiNi-TiC clads was better than that of TiNi. Further investigations indicated that the dominant wear mechanisms in TiNi and TiNi-TiC clad layers were delamination and surface fatigue, respectively.