This work focusses on studying multiphysical transient phenomena in polymer powders occurring during selective laser sintering in polymers powders. Multiple phenomena stemming from the interaction of the laser with the polymer powder bed and the transfer of the laser power to the powder bed including laser scattering and absorption, polymer heating, melting, coalescence, densification, and the variation of the material parameters with the temperature are simulated via the modified Monte Carlo-ray tracing method coupled with the Mie theory. A finite volume method is adopted for the heat transfer. The model couples heat diffusion, melting, coalescence and densification of the polymer grains, and the crystallization kinetics during the cooling steps. Laser intensity is concentrated on the surface of the material contrary to the predictions of the Beer-Lambert law. Laser acting on thermoplastic material cause the polymer powder melt, coalescence between melted grains, air diffusion versus densification, crystallization and volume shrinkage. All these processes are simulated by a series of multiphysical models. The reliability of the modeling is tested by comparison with experiments in the literature, and a parametric analysis is performed, based on the process characteristics such as laser sweep speed, its intensity and shape, polymeric grain size among others. Several recommendations to optimize the process are proposed.

Manufacturing methods to create ceramic coatings with tailored thermal conductivity are crucial to the development of thermal protection systems for many components including turbine blades in high temperature engines. A designed microstructure of grains, pores, and other defects can reduce the thermal conductivity of the ceramic. However, the same microstructure characteristics can reduce mechanical properties to the point of failure. This work is part of a larger program with the goal of optimizing ceramic coating microstructure for thermal protection while retaining sufficient mechanical strength for the intended application. Processing parameters have been examined to identify methods designed to maintain a nano-sized grain structure of yttria-stabilized zirconia while controlling the added porosity with a specific shape and size. In this paper computational modeling is used to evaluate the effects of porosity on coating performance, both thermal and structural. Coating porosity is incorporated in the computational models by randomly placing empty spaces or defects in the shape of spherical voids, oblate pores, or penny cracks. In addition to computational modeling, prototype coatings are developed in the laboratory with specific porosity. The size and orientation of defects in the computational modeling effort are statistically generated to match experiments. The locations of the defects are totally random. Finite element models are created which include various levels of porosity to calculate effective thermal and mechanical properties. Comparisons are made between three-dimensional finite-element simulations and measured data. The influences of pore size as well as three dimensional computational modeling artifacts are examined.

A comprehensive model of the selective laser sintering (SLS) process at the scale of the part is presented for application to polymeric powders. The powder bed is considered as a continuous medium with homogenized properties. A thermal model with detailed multiphysics coupling is presented. The model accounts for all elements of the thermal history : laser absorption, melting, coalescence, densification and volume shrinkage. For numerical resolution, a 3D in-house fortran code using FV method is developed. The proposed model is validated through the comparison of modeling data with experimental results available in the published literature. A parametric analysis about the thermal efficiency of the heating process against the laser energy input is proposed and the influence on the densification and thermal kinetics is discussed with regarding the evolution of the structure of the material.

Stent deployment has been widely used to treat narrowed coronary artery. Its acute outcome in terms of stent under expansion and malapposition depends on the extent and shape of calcifications. However, no clear understanding as to how to quantify or categorize the impact of calcification. We have conducted ex vivo stenting characterized by the optical coherence tomography (OCT). The goal of this work is to capture the ex vivo stent deployment and quantify the effect of calcium morphology on the stenting. A three dimensional model of calcified plaque was reconstructed from ex vivo OCT images. The crimping, balloon expansion and recoil process of the Express stent were characterized. Three cross-sections with different calcium percentages were chosen to evaluated the effect of the calcium in terms of stress/strain, lumen gains and malapposition. Results will be used to the pre-surgical planning.

Virtual Reality (VR) is one of the areas of knowledge that have taken advantage of the computer technological development and scientific visualization. It has been used in different applications such as engineering, medicine, education, entertainment, astronomy, archaeology and arts. A main issue of VR and computer assisted applications is the design and development of the virtual environment, which comprises the virtual objects. Thus, the process of designing virtual environment requires the modelling of the virtual scene and virtual objects, including their geometry and surface characteristics such as colours, textures, etc. This research work presents a new methodology to develop low-cost and high quality virtual environments and scenarios for biomechanics, biomedical and engineering applications. The proposed methodology is based on open-source software. Four case studies corresponding to two applications in medicine and two applications in engineering are presented. The results show that the virtual environments developed for these applications are realistic and similar to the real environments. When comparing these virtual reality scenarios with pictures of the actual devices, it can be observed that the appearance of the virtual scenarios is very good. In particular the use of textures greatly helps in assessing specific features such as simulation of bone or metal. Thus, the usability of the proposed methodology for developing virtual reality applications in biomedical and engineering is proved. It is important to mention that the quality of the virtual environment will also depend on the 3D modelling skills of the VR designer.

The process of heat exchange between two fluids that are at different temperatures and separated by a solid wall occurs in many engineering applications. The device used to implement this exchange is termed a heat exchanger (HE), and specific applications may be found in space heating and air-conditioning, power generation, waste heat recovery, and chemical processing. Increasing heat transfer coefficient and making heat exchanger compact for various applications like in spacecraft, underwater vehicle, unmanned Ariel vehicle is one of the main challenges. Biologically-inspired design (or BID) has become an important and increasingly wide-spread movement in design for environmentally-conscious sustainable development. By definition, BID is based on cross-domain analogies; further, biologically-inspired approaches to design have a certain degree of openness to innovation. Compact heat exchanger can reduce the space and weight of any locomotives and spacecraft. Structural elements inspired from nature possess compactness and stability. Honeycomb structure allows minimize the spacing between cells which makes it possible to use thinnest possible metal boundary wall between two fluids. A rectangle structure can also do the same thing but it has less surface area, which will essentially decrease the volume of heat exchanger. Honeycomb structure provides high surface area to volume ratio which can be utilized to increase heat transfer coefficient of a heat exchanger and thus make compact system. In this computational study, bio-inspired simple honeycomb structured and spiral finned honeycomb structured counter flow heat exchanger has been three dimensionally simulated using finite element methods in commercial software COMSOL. This work is used to reduce the weight of heat exchangers in steam reforming reactors. There is a good correlation when the fluid temperature is the same in all cells. There is also a good temperature gradient in the fluid owing to laminar flow. 3D modeling showed that a careful representation of the inlet is needed for realistic results. A tube-shell heat exchanger is also simulated using FEA in COMSOL. Spiral finned heat exchanger provides additional surface area in cost of pressure drop. The performance characteristics of honeycomb heat exchanger showed an increase in heat transfer rate with least vortex formation.

Cloth has always been the most worldwide of all imported and exported commodities. It is an enlightening example of the movement of knowledge, skills, goods and investment across wide geographic seats. South Asia has been dominant for making of these worldwide interactions over period. This capacity grants advanced research that discovers the dynamic ways in which various textile production and trade regions generated the ‘first globalization’. A series of specialists connect this worldwide commodity with the dramatic political and economic alterations that characterised the India in the recent centuries. Together, the papers transform our understanding of the contribution of South Asian cloth, specifically Indian cloth to make the modern world economy. India is the largest share of its exports being textiles and apparels to the world. Also weaving is second only to agriculture sector in terms of providing employment in India. This paper a simple spreadsheet program method of calculations for the complete kinematics and dynamic analysis of the shedding mechanism of the classical powerloom is presented. Shedding is one of the important processes used in weaving technology of textile machineries. Most of the powerlooms of India uses staubli’s M5 module for shedding. These modules are activated through the traditional slider-crank mechanism. The source energy for these modules is through electric motor coupled with clutch and resulting output is shedding action of warp threads of cloth. Objective of this work is to address the kinematics and Dynamics simulation of linkage assembly of shedding mechanism of textile machinery considering all the links of the model as rigid one. Also this paper examines the effect of dynamic forces on various joints of conventional kinematic model. Subsequently the optimisation of mechanism is carried out by varying the design factor ratio of the slider crank mechanism. Length of connecting rod to radius of the crank shaft has been taken into account for defining design factor ratio for the analysis. Altered varieties of models having various design factors are modeled using 3D modeling package Solidworks. Simulation test results and force analysis of these models were carried out using ADAMS. Being a single degree of freedom mechanism as defined by its crank angle, the spreadsheet program can be used to answer what - if? situation queries through tables and graphical plots to evaluate variations of key motion and loading parameters with changes in the design factor. Thus, it allows for the conduct of parameter studies in selecting optimum crank-and-connecting-rod linkage dimensions and speeds. Thus, this work provides an alternative solution and scope for further research in shedding mechanism’s simulation analysis.

In this work, the 3D design of the stator, rotor of a turbine is performed. A one way coupling between a detailed physicochemical box model and multidimensional Navier-Stokes solver (FLUENT software) is used. Various series of three-dimensional calculations including approximately 500,000 elements are carried out to calculate aero-thermodynamics fields for a first stage of high-pressure turbine of the CFM56 aero-engine. The results show that blades of early turbine stages, directly downstream of combustor are subjected to relatively high levels of unsteadiness generated from complex significant three dimensional shear layers. The latter causes the formation of large-scale turbulent. By consequence, the complex interactions between the geometrical parameters, thermodynamical and chemical processes involving aerosol precursor formation in the turbine are analyzed and investigated.

A finished ceramic component with complex geometries such as micro-channels requires a high degree of dimensional accuracy. This accuracy depends upon precise control of the unfired ceramic body before sintering. One method for creating precise micro-channel geometries is the fugitive phase approach. In this approach, a sacrificial material, the fugitive phase, is used to form channels or voids in the unfired ceramic body. The fugitive phase is removed or sacrificed during the subsequent sintering. For this paper, the authors examine the lamination step of the fugitive phase approach computationally. The lamination step is where the unfired ceramic and fugitive phase pieces are layered and pressed together to remove voids before sintering. The compression of the unfired ceramic during pressing causes pressure gradients, viscoelastic deformation, displacement of the fugitive phase pieces, and rebounding. Three dimensional modeling is used to capture out of plane movement or bending of the long fugitive phase pieces that are used to form long micro-channels. For this research, the unfired ceramic phase consists of tape cast mullite and the fugitive phase is paper. This work primarily examines viscoelastic material models of the unfired ceramic phase for a range of temperatures. The filling of voids, movement of the fugitive phases, pressure gradients, and the rebounding that occurs when the unfired ceramic body is removed from the die press are also noted. The information obtained from computational simulations is used to help direct concurrent experimental investigations.

During fission yeast cytokinesis, actin filaments nucleated by cortical formin Cdc12 are captured by myosin motors bound to a band of cortical nodes. The myosin motors exert forces that pull nodes together into a contractile ring. Cross-linking interactions help align actin filaments and nodes into a single bundle. Mutations in the myosin motor domain and changes in the concentration of cross-linkers alpha-actinin and fimbrin alter the morphology of the condensing network, leading to clumps, rings or extended meshworks. How the contractile tension developing during ring formation depends on the interplay between network morphology, myosin motor activity, cross-linking and actin filament turnover remains to be elucidated. We addressed this question using a 3D computational model in which semiflexible actin filaments (represented as beads connected by springs) grow from formins, can be captured by myosin in neighboring nodes, and get cross-linked with one another through an attractive interaction. We identify regimes of tension generation between connected nodes under a wide set of conditions regarding myosin dynamics and strength of cross-linking between actin filaments. We find conditions that maximize circumferential tension, correlate them with network morphology and propose experiments to test these predictions. This work addresses “Morphogenesis of soft and living matter” using computational modeling to simulate cytokinetic ring assembly from the key molecular mechanisms of viscoelastic cross-linked actin networks that include active molecular motors.

A passive, self-agitating method which takes advantage of vortex-induced vibration (VIV) is presented to disrupt the thermal boundary layer and thereby enhance the convective heat transfer performance of a channel. A flexible cylinder is placed at centerline of a channel. The vortex shedding due to the presence of the cylinder generates a periodic lift force and the consequent vibration of the cylinder. The fluid-structure-interaction (FSI) due to the vibration strengthens the disruption of the thermal boundary layer by reinforcing vortex interaction with the walls, and improves the mixing process. This novel concept is demonstrated by a three-dimensional modeling study in different channels. The fluid dynamics and thermal performance are discussed in terms of the vortex dynamics, disruption of the thermal boundary layer, local and average Nusselt numbers (Nu), and pressure loss. At different conditions (Reynolds numbers, channel geometries, material properties), the channel with the VIV is seen to significantly increase the convective heat transfer coefficient. When the Reynolds number is 168, the channel with the VIV improves the average Nu by 234.8% and 51.4% in comparison with a clean channel and a channel with a stationary cylinder, respectively. The cylinder with the natural frequency close to the vortex shedding frequency is proved to have the maximum heat transfer enhancement. When the natural frequency is different from the vortex shedding frequency, the lower natural frequency shows a higher heat transfer rate and lower pressure loss than the larger one.

One main objective of the technique of reverse engineering is focused on development of new products based on the improvement of existing products. The present work aims to demonstrate a sustainable methodology exploring the capabilities of reverse engineering, applied to produce brand new geometric solutions for safety metallic components incorporated in footwear. The data acquisition is done using different techniques, contact methods (CMM – Measuring Coordinate Machine) and non-contact methods (Laser Scanning). Those measuring techniques for data acquisition are the key entry for the 3D shape recovery, boosting the development of new components based on the improvement of existing products. Despite these techniques being widely explored in multiple engineering sectors, author’s contribute was focused on the proposal and validation of a sustainable methodology based on an algorithm in MATLAB that performs the surface generation under user control. Such methodology has been tested through a real model of a toecap component used in safety footwear.

For many years, literature has documented the benefits of project-based learning (PBL) and its impact on student learning especially at the high school level. More often than not however, students are still losing interest in STEM (Science, Technology, Engineering, and Mathematics) education because current educational teaching pedagogies have become antiquated and are not impacting student learning, as it should. With that said, our discovery through elicitation of high school educators has cited the main reason for such disinterest is due to the inability of students to connect STEM abstract concepts and theory with STEM application to appreciate the value of learning STEM. With access to information easier than ever, students are forgetting that learning is not about getting the right answer but understanding how to solve a complex problem. In the past, PBL has benefited students in engaging them in hands-on learning however, with a more complex paradigm shift in student learning style, PBL and lecture-based learning are no longer the most effective methods of teaching. Engineering-based learning has the opportunity and potential to modify STEM education and revolutionize STEM teaching pedagogy by changing the one-size-fits-all model to an individual, student-centered learning approach where education is mass customized. This paper discusses a new teaching pedagogy dubbed Engineering-Based Learning (EBL) that is a more systematic approach to high school STEM teaching for open-ended problems. This paper presents the EBL model, the EBL tools, and its impact thus far on high school students. It also presents sample feedback from both teachers and students and how it has influenced their outlook of engineering and STEM in the real world. The purpose of this paper is also to disseminate this new teaching pedagogy to support the notion that STEM education can be successfully taught and provide students with a structured, systematic, hands-on approach, as well as the appropriate tools and resources allowing them to connect complex STEM theory and real-world application.

In this work, the stents-induced mechanical responses of a patient-specific common carotid artery (CCA) were evaluated through computational simulation. The realistic 3D geometry of the artery was constructed from the MRI data. Two types of self-expanding stent design (open-cell and closed-cell) were used to restore the blood flow inside the 60% stenosed artery. The resulting lumen gain, dog-boning effect and arterial stress were estimated. Results suggested that the artery was straightened after stent implantation, and the open-cell design led to bigger lumen gain, better conformability, and less dog-boning effect. This work may facilitate the development of new stent designs.

Blast induced traumatic brain injury (bTBI) is signature injury in recent combat scenarios involving improvised explosive devices (IEDs). The exact mechanisms of bTBI are still unclear and protective role of helmet and body armor is often questioned [1–3]. High Fidelity finite element models involving fluid structure interaction are built in order to understand effectiveness of helmet in mitigating early time blast induced mild traumatic brain injury.

This paper discusses the alignment between industry needs and the content of a 4 year ME or MET curriculum by using Product Lifecycle Management (PLM) principles as a bridge. An initial concept for a device is used as an example throughout the 4 year curriculum, allowing the courses to progressively develop the design from concept through end-of-life by using PLM principles. The four-year curriculum discussed begins with an introduction to PLM, where the steps of a manufacturing process are described, from concept, to 3D design, to analysis, to final product to end of life. This provides the basis for a design concept that will be pursued throughout the curriculum. The four-year curriculum is then presented as a traditional engineering program with a superimposed design problem. The freshman curriculum includes the basic 3D modeling of the parts, while the sophomore classes generate the first prototype parts and beginning analyses. The junior classes progress into more involved stress and thermo/fluid analysis of the part, while the senior classes look into the mass manufacture of the part; it’s interaction with the rest of the system and the systems role in serving society. Students are well prepared for industry, with improved knowledge of design methods, manufacturing processes, life cycle issues and how these different areas can work together to make a successful design. The use of PLM as an over-arching theme brings it into the classroom in a practical hands-on way with minimal impact on the existing class content while improving the delivery by bringing continuity to the problems.

The work presented in this paper is part of a larger project for the modeling of dynamic behavior in bolted joints, and it is a further work on the adjustment of bolted joint 3D numerical model. This work shows the study and conclusions of the numerical modeling of a bolted lap joint by means of 1D hysteresis finite element and its validation with dynamical tests. The modeled joint is made up of two plates with a bolt, nut and washer. The behavior curve of the hysteresis element used was obtained by means of a 3D model of the joint, whose parameters and validation were carried out from the results of quasi-static laboratory tests. This procedure could be advantageously extended to any other lap joint given that its computational requirements are less than those required for a detailed 3D modeling.

Graduates from the Associate in Applied Science (AAS) in Mechanical Engineering Technology (MECH) and Industrial Design (IND) Technology at New York City College of Technology are learning new skills in 3D modeling, Finite Elements Analysis (FEA) and Rapid Prototyping. Two year programs in engineering technology are often short of helping students to grasp all aspects of the technology. This is mainly due to the limited number of credits allowed in 2-year programs (about 60 credits). Most graduates from both MECH and IND find employment in the local industry. Growing demand from local employers compelled the department to incorporate new components in the upper level courses in both AAS programs. Students from both programs are required to take a 60 hour (4 hours/week) Advanced Solid Modeling course (IND2304). In order to address the local industry need the department decided to modify and update IND2304. In the new course, students learn to improve their design by using some of the solid mechanics techniques, stress analysis, the role of Finite Element Analysis (FEA), rapid prototyping, and applying tolerance. Students learn 3D modeling using AutoDesk Inventor. They are required to design a team based project at the end of the semester. Students learn team work and sharing information with each other. They enhance their communication skills by presenting their work at the end of the semester. Results of this new course are very encouraging. Students get very motivated by the diversity and creativity of the new design work. Some students who graduated from both programs were able to use their new design skills and team work in their current positions in the field.

Root canal treatment of infected root canals represents a large percentage of business in general dental practice. It is an expensive process and often prone to failure. During root canal treatment, destructive access preparation by removing parts of tooth crown and dentin is usually needed even before a clinician’s inspection and diagnosis. This paper presents a non-destructive method for accessing the internal tooth geometry by building a 3-D tooth model from 2-D radiograph. The geometry of root canals is then formulated into a mathematical model. Based on this mathematical model, the treatment procedures utilizing the dental tools/instruments are planned by a computer aided prescription system, which yields the tool selection and tool path for the root canal preparation by an intelligent micro drilling machine with on-line monitoring. To minimize the removal of healthy tooth crown and dentin, thus protecting the strength of the patient’s infected tooth, an optimization algorithm is utilized for planning the access preparation in the root canal treatment. Although an opening of a tooth crown is still needed so that dental instruments can reach the root canal, the non-destructive 3-D modeling and the optimization of the access preparation in the new approach makes the root canal treatment minimally invasive compared to present techniques.

Although in the last few years, the use of the non-invasive medical techniques for diagnosis and treatment has experienced a huge development, mainly due to advancement in technology, for research and education these methods are still elaborate, expensive and not readily accessible. The purpose of our study was to compare the accuracy of an unconventional, non-invasive and relatively inexpensive Microscribe (3D digitizer) with a standard widely used and expensive CT-Scan and/or MRI for 3D reconstruction of a human skull, which will be used for biomechanics studies. Two models of the human skull were developed (reconstructed), one using the 3D coordinates generated by the Microscribe 3D digitizing unit and another one using the CT-Scans (2D cross-sections) obtained from a GE scanner. Using the hand-held digitizer, the Microscribe, X, Y and Z coordinates of a human skull were generated to create the first computer model. The 3D coordinates were brought as splines in to 3D Studio Max, a 3D modeling software, and U-lofted to form a solid NURBS model. The Microscribe captures the physical properties of a three-dimensional object and translates them into a 3D model. This kind of device is used to collect data directly from the surface of the study object. The stylus tip is moved over the contour of the object following its surface until the entire surface is digitized. Usually, points are drawn on the object’s surface in order to facilitate the digitizing process. 3D Studio Max takes this “raw” data and produces complex 3D models using various modeling techniques. For making the first skull model a technique called DRAW SPLINES was used. This method allows the user to begin a new spline or to do multiple splines by adding splines to those already created. I used this command to digitize my model because it is easy to use, quick and it gives the most accurate result. The final model was obtained in three steps: half of the skull was digitized and the first object was obtained, the MicroscribeSpline object (Fig. 1). The splines were transformed in NURBS curves and the second object was called NURBS Curves object. Finally, in the third phase, the NURBS curves were transformed in NURBS surfaces using the NURBS surface command, U-LOFT, and the final model, NURBS surface object, was obtained (Fig. 2). The entire skull was obtained from 2 identical halves of the same skull. The model was created using symmetry method because of the model’s organic complexity. The solid model was then exported to FEA software for analysis. (Fig. 3) The second skull model was created using the 2-D cross-sections obtained from the GE Helical Hi Speed - FX/i scanner (Fig. 4). The same skull used in the first part of the study, for modeling the first virtual model, was scanned following both sagittal and frontal planes. The interslice distance was set as being 3 mm. 48 CT slices for every analyzed plane were obtained. The CT cross-sections were captured as DICOM files using the E-film software and exported as TIFF images. The TIFF images were brought into OPTIMAS (image analysis software), which extracted the X, Y coordinates of each cross section using the POINT MORPHOMETRY option. A visual basic program was developed to convert the extracted coordinates to closed curves under Unigraphics SolidEdge software. To obtain the final model, the external boundaries of each cross section were lofted using LOFT PROTRUSION command. To find the best result, a second approach was developed in parallel using Adobe STREAMLINE and image processing software, which extracts the boundaries of each cross section and exports them as DXF files, compatible with the Solid Edge program. Both models were then subjected to stress analysis using Finite Element Analysis software. The analysis results obtained from the two scanning techniques will be discussed and presented, including the pros and cons of using the more accurate and expensive CT-scans versus the inexpensive hand-held scanner and their effects on finite element models. For this study, different image processing software such as OSIRIS, SCION IMAGE, EFILM, 3D DOCTOR, OPTIMAS and STREAMLINE were investigated in order to find the best interface to capture, reconstruct and model body data. The features, availability, cost and user-friendliness of these software tools will also be presented.