bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparative Study of As-Built Geometric and Mechanical Properties of Additively Manufactured Ceramics
Authors: Steuben John C. , Iliopoulos Athanasios P. , Michopoulos John G.
Published: November 2018

Additive Manufacturing (AM) encompasses a broad variety of fabrication techniques characterized by successive additions of mass and/or energy to a build domain. AM processes have been developed for a wide variety of feedstock materials, including metals, polymers, and ceramics. In the present work we study the AM of ceramics using the Direct Ink Writing (DIW) technique. We performed comparative studies between additively manufactured and conventionally manufactured test articles, in order to quantify the variations in output geometry and mechanical properties induced by the DIW process. Uniaxial tests are conducted using high-performance optical strain measurement techniques. In particular, it is shown that the DIW-produced specimens exhibit anisotropic shrinkage when fired, as well as a marked decrease in stiffness and ultimate strength. We conclude with a discussion of potential mechanisms which may be responsible for these property degradations, and introduce potential adaptations to the DIW AM process that may be effective in combating them.
Design and Test of an Autonomous Reconfigurable Dynamic Investigation Test-Rig on Haptics (ARDITA) for Pre-Screening of the Peripheral Neuropathy Diseases
Authors: D’Angelo Maria Laura , Caldwell Darwin , Cannella Ferdinando , Liberini Paolo , Padovani Alessandro , Lazzarini Clara , Pilotto Andrea
Published: November 2018

This work presents a new device ARDITA (Autonomous Reconfigurable Dynamic Investigation Test-rig on hAptics) that is able to indent the fingertip with sinusoidal waves. Its reconfigurability permits to change these waves in amplitude, spatial and timing frequencies. The device is designed in order to be autonomous and reconfigurable, but also the portability and the size were taken into account, because the clinicians had to move it from an hospital to the other one and because each patient arms has a different size. In this work, the authors applied this feature to investigate the relationship between the tactile sensitivity of index and little finger both in healthy people and people who suffer peripheral neuropathies as the Carpal Tunnel Syndrome (CTS). The last ones were examined also with the Electromyography (EMG). 40 healthy people and 17 ill patients were tested. The results showed that ARDITA determined not only the index and little finger performance were inverted in patients respect to the subject, but also the increment of incorrect responses were perfected correlated with the increment of the degree of the illness.
A Super-Metamodeling Framework to Optimize System Predictability
Authors: Yang Zhuo , Eddy Douglas , Krishnamurty Sundar , Grosse Ian , Lu Yan
Published: November 2018

Statistical metamodels can robustly predict manufacturing process and engineering systems design results. Various techniques, such as Kriging, polynomial regression, artificial neural network and others, are each best suited for different scenarios that can range across a design space. Thus, methods are needed to identify the most appropriate metamodel or model composite for a given problem. To account for pros and cons of different metamodeling techniques for a wide diversity of data sets, in this paper we introduce a super-metamodel optimization framework (SMOF) to improve overall prediction accuracy by integrating different metamodeling techniques without a need for additional data. The SMOF defines an iterative process first to construct multiple metamodels using different methods and then aggregate them into a weighted composite and finally optimize the super-metamodel through advanced sampling. The optimized super-metamodel can reduce an overall prediction error and sustains the performance regardless of dataset variation. To verify the method, we apply it to 24 test problems representing various scenarios. A case study conducted with additive manufacturing process data shows method effectiveness in practice.
Design of a Graphene Nanoribbon Electrostatic Discharge Compliant Mechanism
Authors: Jones Talmage H. , Ng Jimmy , Xie Ya-Hong , Hopkins Jonathan B.
Published: November 2018

This paper investigates the design of an electrostatic discharge protection device made of single-layer graphene nanoribbons. The device is meant to trigger electrostatic discharge at a target voltage of 1.5V. Other design requirements include the minimization of parasitic capacitance, electrical response time and mechanical response time. The device is designed to discharge static electricity by being pulled to ground through electrostatic forces, then making contact with ground before returning to its original position. Previous designs experienced repeatability issues due to a lack of securing the ribbon and mechanical failure due to high stresses at the boundary conditions. New designs are presented and optimized to maintain a high effective spring constant for the device while reducing stress during electrostatic pull-in. A single-degree of freedom model is used in conjunction with the Bernoulli-Euler beam equations and Castigliano’s method to guide the design process. Behavior of each design is validated, and repeatability is assessed using finite-element simulations. The new designs are to be fabricated using a low pressure chemical vapor deposition process.
On the Multiphysics Modeling of the Sliding Wear Between Deformable Heat Conducting Bodies
Authors: Michopoulos John G. , Iliopoulos Athanasios P. , Steuben John C. , Birnbaum Andrew J.
Published: November 2018

An approach exploiting the relevant conservation laws associated with the wear due to sliding between deformable heat conducting bodies is presented in this work. The proposed methodology considers a pair of wearing objects in contact where their wear behaviors are encapsulated by semantically reduced one-dimensional, time-dependent ordinary differential equations (ODEs) as a replacement to the full mass conservation PDEs governing mass loss due to the various mechanisms present at the interface. At the same time, the conservation of energy and momentum are still expressed by the full form of the PDEs representing them. To assess the feasibility of this approach a reciprocating sliding contact pair of dissimilar materials is considered. The high dimensional thermo-mechanical problem is solved simultaneously and tightly coupled with the two ODE wear models for each of the wear pair bodies, thus enabling predictions of wear for both of them. Furthermore, an Arbitrary-Lagrangian-Eulerian (ALE) approach has been used to produce the evolution of the wear fronts on both elements of the sliding contact pair through physics-informed mesh deformation consistent with the results computed in the previous step. The main advantage of this approach enables the usage of any low dimensional wear model (i.e, mechanical failure, phase transformation-based, etc.) in a computationally detailed and efficient manner.
Design of Planar Shape-Morphing Mechanism Arrays Using Harmonic Mechanisms
Authors: Lusk Craig
Published: November 2018

is paper introduces a design concept for planar mechanism arrays using an interesting property of mechanisms that I have termed mechanism harmony. Just as a theory of musical harmony allows for a large number of notes to be played without harsh-sounding interference, mechanism harmony allows mechanism links to be arrayed so that they move coherently and with a small degree of freedom. The concept of mechanism harmony is based on permuting the arrangement of the moving links. For a four-bar mechanism, this yields six (3!) different harmonic permutations of the link arrangement, and there are numerous ways that these six different mechanisms can be grouped together to tile the plane. This paper presents early findings on these groups, some prototypes showing arrays with harmonic motion, and discusses the possible significance of harmonic mechanisms for shape morphing mechanisms.
A Statistical Approach to Ranking Similarities of Three Function Structure Groups Using Directed Graphs
Authors: Lucero Briana M. , Adams Matthew J.
Published: November 2018

Prior efforts in the study of engineering design employed various approaches to decompose product design. Design engineers use functional representation, and more precisely function structures, to define a product’s functionality. However, significant barriers remain to objectively quantifying the similarity between two function structures, even for the same product when developed by multiple designers. For function-structure databases this means that function-structures are implicitly categorized leaving the possibility of incorrect categorization and reducing efficacy of returned analogous correlations. Improvements to efficacy in database organization and queries are possible by objectively quantifying the similarity between function structures.

The proposed method exploits fundamental properties of function-structures and design taxonomies. We convert function-structures into directed graphs (digraphs) and equivalent adjacency matrices. The conversion maintains the directed (function → flow → function) progression inherent to function-structures and enables the transformation of the function-structure into a standardized graph. For design taxonomies (e.g. D-APPS), graph nodes represent flows in a consistent (but arbitrary) ordering. By exploiting the directional properties of function-structures and defining the flows as the graphical nodes, the objective and standardized comparison of two function-structures becomes feasible. We statistically quantify the association between digraphs using the Pearson Product Moment Correlation (PPMC) for both within-group and between-group comparisons. The method was tested on three product types (ball thrower, food processor, and an ice cream maker) with function-structures defined by various designers. The method suggested herein is provided as a proof-of-concept with suggested verification and validation approaches for further development.
Fabrication of PLA/CNT Composite Scaffolds by Fused Deposition Modeling
Authors: Rebaioli Lara , Pagano Claudia , Fassi Irene
Published: November 2018

The Fused Deposition Modeling (FDM) technology can be successfully used to manufacture biodegradable polymeric scaffolds for tissue reconstruction in case of critical size bone damages. Carbon nanotubes (CNTs) are able to mimic the extracellular matrix and their addition can improve the mechanical and electrical properties of polymers. In this way, the scaffolds are more likely to match the host bone properties and the cell adhesion, differentiation and proliferation can be enhanced. In this paper scaffold-like specimens, manufactured by FDM technology, are tested to evaluate the conductivity increase in PLA/CNT composite compared to pure PLA (polylactid acid).
Function Modeling: An Analysis of Pause Patterns in Modeling Activities
Authors: Patel Apurva , Kramer William S. , Flynn Michelle , Summers Joshua D. , Shuffler Marissa L.
Published: November 2018

This paper presents a protocol study conducted with mechanical engineering students, where the participants developed a function structure model for a novel design problem. A modeling activity video was recorded for each participant and coded using a protocol analysis. Pauses in the modeling process were analyzed to identify patterns based on pause time and frequency, distribution of pauses over the modeling activity, events following the pauses, and elements added after pauses. Results show that participants used an average of 38% of the modeling time in pauses with a pause frequency of 41%. Moreover, participants were also found to spend more time in pauses during the second and third quarters of the modeling activity. Subsequently, an analysis of pause lengths revealed three different pause groups corresponding to short, intermediate, and long pauses. Participants added elements to the model significantly more frequently, compared to editing and deleting elements. Instances of deleting were found to be more likely to occur after longer pauses, whereas editing was done more frequently after shorter pauses. Participants paused more frequently before adding flows, and more frequent pauses were observed before labeling function compared to adding function blocks. The flows were found to be labeled after pauses infrequently. Finally, limitations of the study are discussed, and future research questions have been identified.
Multi-Criteria Evolution of Neural Network Topologies: Balancing Experience and Performance in Autonomous Systems
Authors: Chidambaran Sharat , Behjat Amir , Chowdhury Souma
Published: November 2018

Majority of Artificial Neural Network (ANN) implementations in autonomous systems use a fixed/user-prescribed network topology, leading to sub-optimal performance and low portability. The existing neuro-evolution of augmenting topology or NEAT paradigm offers a powerful alternative by allowing the network topology and the connection weights to be simultaneously optimized through an evolutionary process. However, most NEAT implementations allow the consideration of only a single objective. There also persists the question of how to tractably introduce topological diversification that mitigates overfitting to training scenarios. To address these gaps, this paper develops a multi-objective neuro-evolution algorithm. While adopting the basic elements of NEAT, important modifications are made to the selection, speciation, and mutation processes. With the backdrop of small-robot path-planning applications, an experience-gain criterion is derived to encapsulate the amount of diverse local environment encountered by the system. This criterion facilitates the evolution of genes that support exploration, thereby seeking to generalize from a smaller set of mission scenarios than possible with performance maximization alone. The effectiveness of the single-objective (optimizing performance) and the multi-objective (optimizing performance and experience-gain) neuro-evolution approaches are evaluated on two different small-robot cases, with ANNs obtained by the multi-objective optimization observed to provide superior performance in unseen scenarios.
Computer Implementation of Hierarchical FE-DE Multiscale Approach for Modeling Deformable Soil in Multibody Dynamics Simulation
Authors: Yamashita Hiroki , Chen Guanchu , Brauchler Alexander , Ruan Yeefeng , Jayakumar Paramsothy , Sugiyama Hiroyuki
Published: November 2018

In this paper, a hierarchical FE-DE multiscale soil model is implemented and validated for use in multibody dynamics simulation. In order to describe complex soil failure phenomena including strain localization, the finite-element (FE) model is utilized to predict macroscale soil deformation, while the microscale constitutive behavior is modeled by representative volume elements (RVEs) using the discrete-element (DE) method. Brick elements integrated in the general multibody dynamics algorithm are used for developing the macroscale model. An open-source DE code LIGGGHTS is integrated in this simulation framework to add multiscale simulation capabilities for modeling complex soil behavior. Several numerical examples are presented to demonstrate the use of multiscale simulation capabilities for high-fidelity multibody off-road mobility simulations.
Resolving the Unique Invariant Slip-Direction in Rigid Three-Dimensional Multi-Point Impacts at Stick-Slip Transitions
Authors: Chatterjee Abhishek , Bowling Alan
Published: November 2018

This work presents a new approach for resolving the unique invariant slip direction at Stick-Slip Transition during impact. The solution method presented in this work is applicable to both single-point and multi-point impact problems. The proposed method utilizes rigid body constraints to resolve the impact forces at all collision points in terms of a single independent impact forces parameter. This work also uses an energetic coefficient of restitution to terminate impact events, thereby yielding energetically consistent post-impact behavior.
A Motion Formalism Approach to Modal Reduction for Flexible Multibody System Applications
Authors: Sonneville Valentin , Bauchau Olivier A. , Brüls Olivier
Published: November 2018

Multibody systems are often modeled as interconnected multibody and modal components: multibody components, such as rigid bodies, beams, plates, and kinematic joints, are treated via multibody techniques whereas the modal components are handled via a modal reduction approach based on the small strain assumption. In this work, the problem is formulated within the framework of the motion formalism. The kinematic description involves simple, straightforward frame transformations and leads naturally to consistent deformation measures. Derivatives are expressed in local frames, which results in the remarkable property that the tangent matrices are independent of the position and orientation of the modal component with respect to an inertia frame. This implies a reduced level of geometric non-linearity as compared to standard description. In particular, geometrically non-linear problems can be solved with the tangent matrices of the reference configuration, without re-evaluation and re-factorization.
Harmonically Excited Delay Equation for Machine Tool Vibrations
Authors: Lelkes János , Kalmár-Nagy Tamás
Published: November 2018

A machining tool can be subject to different kinds of excitations. The forcing may have external sources (such as rotating imbalance or misalignment of the workpiece) or it can arise from the cutting process itself (e.g. chip formation). We investigate the classical tool vibration model which is a delay-differential equation with a quadratic and cubic nonlinearity and periodic forcing. The method of multiple scales was used to derive the slow-flow equations. The resonance curves of the system are similar to those for the Duffing-equation, having a hardening characteristic. Stability analysis for the fixed points of the slow-flow equations was performed. Local and global bifurcations were studied and illustrated with phase portraits and direct numerical integration of the original equation. Subcritical Hopf, saddle-node and heteroclinic bifurcations were found.
Orientation Planning for Multi-Agents With Discrete-Step Locomotion and Multiple Goals
Authors: Sagar Keerthi , Zlatanov Dimiter , Zoppi Matteo , Nattero Cristiano , Muthuswamy Sreekumar
Published: November 2018

The paper addresses the coordinated path planning of mobile agents with multiple goal positions and orientations in a plane. The targeted multi-robot system uses discrete locomotion ensuring uncertainty-free localization and mapping as well as simple and robust control. It is suitable for material-handling, reconfigurable-fixturing, and mobile-manipulation tasks in a flexible-manufacturing environment. Using its three leg, and matching pin-socket couplings with the base surface, each agent either stands fixed or strides along via “Swing and Dock” (SaD) locomotion. Each mounting pin can serve both as a connecting-locking device and as a pivot of a planar rotation. Previous work offered planning solutions only for the agents’ positions. In reality, the orientation in which the agent arrives at the goal is very important because neither robot workspaces nor workcell geometries have axial symmetry. Herein, we provide for the required orientational planning by labelling the agent’s legs to keep track of its rotation. Integer Linear Programming (ILP) is used to model the path planning problem in the so augmented configuration space. The mathematical formulations are implemented and tested using a GUROBI solver. Computational results display the effectiveness of the approach.
Analysis and Dimensional Synthesis of a Robotic Hand Based on the Stewart-Gough Platform
Authors: McCann Connor M. , Dollar Aaron M.
Published: November 2018

In this paper, we study the dimensional synthesis of a Stewart-Gough platform-inspired dexterous robotic hand, seeking to optimize the hand’s geometric design parameters to achieve the largest possible 6-degree-of-freedom workspace of a grasped object serving in the place of the “platform.” We present an analysis of the hand mechanism that considers both object stability from frictional contact forces as well as kinematic motion transmissibility, seeking a balance between these two properties. We examine the effect of variations in the kinematic and frictional parameters on both the workspace size of the hand as well as on the motion quality throughout the workspace across a range of grasped object sizes. We then present a spectrum of optimal designs that weight these two performance criteria differently. Most notably, the palm radius of the hand was found to have the greatest effect on the workspace size, with smaller palms exhibiting significantly larger workspaces. Overall, this work serves to inform the design process for dexterous robotic hands based on this common kinematic configuration, with the ultimate goal of increasing the dexterity of robotic manipulators to facilitate more versatile interactions with the environment.
Over-Design Versus Redesign As a Response to Future Requirements
Authors: Allen Jeffrey D. , Stevenson Phillip D. , Mattson Christopher A. , Hatch Nile W.
Published: November 2018

Though little research has been done in the field of over-design as a product development strategy, an over-design approach can help products avoid the issue of premature obsolescence. This paper compares over-design to redesign as approaches to address the emergence of future requirements. Net present value (NPV) analyses of several real world applications are examined from the perspective of manufacturers and customers. This analysis is used to determine the conditions under which an over-design approach provides a greater benefit than a redesign approach. Over-design is found to have a higher net present value than redesign when future requirements occur soon after the initial release, discount rates are low, initial research and development cost or price is high, and when the incremental costs of the future requirements are low.
An Investigation Into the Dynamics of a Pipe Aspirating Fluid
Authors: Butt Muhammad Faisal Javed , Paidoussis Michael P. , Nahon Meyer
Published: November 2018

Pipes aspirating fluid have applications in the filling and recovery processes for underground caverns — large subterranean cavities used to store hydrocarbons, such as natural gas and oil. This paper deals with the dynamics of a vertical cantilevered flexible pipe, immersed in fluid. Fluid is aspirated from its bottom free end up to the fixed upper end. In this study, the working fluid is assumed to be water.

An existing analytical model is used to predict the dynamical behaviour of the aspirating pipe. This model is then discretized with Galerkin’s method, using Euler-Bernoulli eigen-functions for cantilevered beam as comparison functions. Once solved, the model results show a unique kind of flutter comprising three regions, denoted regions 01–03. These regions are delineated by two critical flow velocities, Ucf1 and Ucf2. In addition, two frequencies of oscillation, f1 and f2, are found to characterize the aforementioned flutter. The dominant frequency of oscillation changes from f1 to f2 as the flow velocity is increased from approximately 3 to 6 m/s — a frequency exchange phenomenon observed and reported here for the first time for this system. The analytical/numerical study was followed by a corresponding experimental study. Experiments were performed on a flexible (Silastic) pipe that was completely submerged in water. The behaviour observed experimentally was similar to the numerical study, as the aspirating fluid velocity was increased from zero to 7 m/s.
Preliminary Field Test Results From a Photovoltaic Electrodialysis Brackish Water Desalination System in Rural India
Authors: He Wei , Wright Natasha C. , Amrose Susan , Buonassisi Tonio , Peters Ian Marius , Winter Amos G.
Published: November 2018

Brackish water desalination is crucial to meet basic drinking water needs in rural India. Solar photovoltaic powered electrodialysis (PV-ED) has been justified as a more cost-effective solution than the current dominant reverse osmosis approach for off-grid systems. This paper presents preliminary results from an ongoing field pilot of a village-scale PV-ED system in Chelluru, which is a small village in South India. System performance is compared to predictions of a PV-ED parametric model of local solar irradiance, ED system parameters, power systems parameters, water storage, and cost, validating the model over a single-batch ED operation. An ∼88% “solar-to-treated water” conversion efficiency was achieved in a typical ED batch operation, using 2.47±0.27 kWh/m3 for brackish desalination in the village. This paper also discusses the difficulties and local constraints encountered during the initial field testing and analyzes system performance in the context of local constraints and availability.
Function Ordering Within Morphological Charts: An Experimental Study
Authors: Chawla Anant , Summers Joshua D.
Published: November 2018

Morphological charts are widely recognized tools in engineering design applications and research. However, a literature gap exists in instructing the representation and exploration of morphological charts. In this paper, an experiment is conducted to understand how morphological charts are explored and what impact functional arrangement has on it. The experiment consisted of two problem statements, each with five different functional arrangements: 1) Most to Least Important Function, 2) Least to Most Important Function, 3) Input to Output Function, 4) Output to Input Function, and 5) Random. Sixty-seven junior mechanical engineering students were provided a prepopulated morphological chart and asked to generate integrated design concepts. The generated concepts were analyzed to determine how frequently a given means is selected, how much of the chart is explored, what is the sequence of exploration, and finally the influence of function ordering on them. Experimental results indicate a tendency to focus more on the initial columns of the chart irrespective of functional order. Moreover, the Most-to-Least-Important functional order results in higher chances and uniformity of design space exploration.
Vision-Based Hand Gesture Recognition With Deep Machine Learning for Visual Servoing
Authors: Al-Shanoon Abdulrahman , Lang Haoxiang , Wang Ying
Published: November 2018

Vision based robot motion control (Visual Servoing) is a challenging research direction in utilizing vision information to control the robot motion. In this work, we successfully controlled the real-time pose of an end-effector based on a hand gesture detector that we trained with acquired training data in the lab environment. Meanwhile, a machine learning model for hand language translation based on convolutional neural network is proposed and utilized in this paper. SSD is the suggested meta-architecture that uses single feed-forward convolutional network for straightly predicting categories. The proposed model is evaluated on Tensorflow platform along with Pascal VOC 2012. In addition, an image-based vision servoing system based on Lyapunov’s theory is developed to control velocities of the robot’s joints. In the experimentation, the integration of the above systems and MobileNet network as a convolutional feature extractor shows good performance in identification, tracking and motion control of the robot. The model achieved 98% mAP and 0.8 for Total-loss while visual servoing also demonstrated good performance during experimentation.
Knowledge-Based Optimization of Artificial Neural Network Topology for Process Modeling of Fused Deposition Modeling
Authors: Nagarajan Hari P. N. , Jafarian Hesam , Hamedi Azarakhsh , Mokhtarian Hossein , Prod'hon Romaric , Tilouche Shaima , Coatanéa Eric , Nenchev Vladislav
Published: November 2018

Additive manufacturing (AM) continues to rise in popularity due to its various advantages over traditional manufacturing processes. AM interests industry, but achieving repeatable production quality remains problematic for many AM technologies. Thus, modeling the influence of process variables on the production quality in AM can be highly beneficial in creating useful knowledge of the process and product. An approach combining dimensional analysis conceptual modeling, mutual information based analysis, experimental sampling, factors selection, and modeling based on Knowledge-Based Artificial Neural Network (KB-ANN) is proposed for Fused Deposition Modeling (FDM) process. KB-ANN reduces the excessive amount of training samples required in traditional neural networks. The developed KB-ANN’s topology for FDM, integrates existing literature and expert knowledge of the process. The KB-ANN is compared to conventional ANN using prescribed performance metrics. This research presents a methodology to concurrently perform experiments, classify influential factors, limit the effect of noise in the modeled system, and model using KB-ANN. This research can contribute to the qualification efforts of AM technologies.
Human Box Delivering Simulation by Subtask Division
Authors: Owens Paul , Xiang Yujiang
Published: November 2018

This study addresses one solution for determining the optimal delivery of a box. The delivering task is divided into five subtasks: lifting, initial transition step, carrying, final transition step, and unloading. Each task is simulated independently with appropriate boundary conditions so that they can be stitched together to render a complete delivering task. Each task is formulated as an optimization problem. The design variables are joint angle profiles. For lifting and carrying tasks, the objective function is the dynamic effort. In contrast, for transition task, the objective function is the combination of dynamic effort and joint angle discomfort. For unloading, it is a reverse process of lifting motion. A viable optimization motion is generated from the simulation results. The joint torque, joint angle, and ground reactive forces are analyzed for the delivering motion which is also empirically validated.
Information Reuse to Accelerate Customized Product Slicing for Additive Manufacturing
Authors: Ye Hang , Kwok Tsz-Ho , Zhou Chi , Xu Wenyao
Published: November 2018

Different from most traditional manufacturing processes, the productivity of additive manufacturing (AM) is independent of the geometric complexity from the object to be built. This characteristic opens up tremendous potentials to realize mass customization. However, the AM-specific parts, such as customized products, need to be represented by millions of triangle meshes. Moreover, a large number of sliced layers are needed with the increased resolution of AM machines. These together pose a fundamental challenge in slice generation. The slicing procedure for a single customized model can take tens of minutes or even hours to complete, and the time consumption becomes more prominent in the context of mass customization. We propose a new slicing paradigm which capitalizes upon the similarities among customized models, and it reuses information obtained from the template model slicing. The idea of information reuse is implemented at several different levels depending on variations between the customized model and the template model. Experimental results show that the proposed slicing paradigm can significantly reduce the time consumption on slicing process, and ultimately fulfill mass customization enabled by AM.
Sensitivity Analysis of Flexible Multibody Systems Based on the Motion Formalism and the Discrete Adjoint Method
Authors: Callejo Alfonso , Sonneville Valentin , Bauchau Olivier A.
Published: November 2018

The combination of analysis and optimization methods in mechanical engineering, also known as design optimization, has great potential in product development. Robust sensitivity analyses that provide reliable and efficient objective function gradients play a key role in design optimization. This paper presents a discrete adjoint method for the sensitivity analysis of flexible mechanical systems. The ultimate goal is to be able to relate the physical properties of beam cross-sections to the dynamic behavior of the system, which is key to design realistic flexible elements. The underlying flexible multibody formulation is one that supports large-amplitude motion, beams with sophisticated composite cross-sections, and kinematic joints. A summary of the kinematic and dynamic foundations of the forward equations is presented first. Then, a discrete adjoint method, along with meaningful examples and validation, is presented. The method has proven to provide extremely accurate and reliable sensitivities.
A Problem Class With Combined Architecture, Plant, and Control Design Applied to Vehicle Suspensions
Authors: Herber Daniel R. , Allison James T.
Published: November 2018

Here we describe a problem class with combined architecture, plant, and control design for dynamic engineering systems. The design problem class is characterized by architectures comprised of linear physical elements and nested co-design optimization problems employing linear-quadratic dynamic optimization. The select problem class leverages a number of existing theory and tools and is particularly attractive due to the symbiosis between labeled graph representations of architectures, dynamic models constructed from linear physical elements, linear-quadratic dynamic optimization, and the nested co-design solution strategy. A vehicle suspension case study is investigated and a specifically constructed architecture, plant, and control design problem is described. The result was the automated generation and co-design problem evaluation of 4,374 unique suspension architectures. The results demonstrate that changes to the vehicle suspension architecture can result in improved performance, but at the cost of increased mechanical complexity. Furthermore, the case study highlights a number of challenges associated with finding solutions to the considered class of design problems.
Shock and Vibration Isolation Using Dynamic Mounts With Internal Damping
Authors: Blandino Theresa , Ferri Aldo
Published: November 2018

Shock isolation systems are often modeled as having lumped stiffness and damping characteristics. However, the isolation performance may be improved if the isolation mount is allowed to have internal dynamics. Previous work has considered several different ways of disrupting the disturbance as it propagates along the length of a multi-degree-of-freedom mount. In this paper, the role of internal damping of the mount is re-examined. Furthermore, the damping model is extended to allow different levels of damping in different response regimes. Through simulation of the shock response, the findings show that the optimal level of internal damping depends on the magnitude of the input shock. For small shocks, performance is best for a relatively high level of damping, but for larger shocks, the best damping value drops to a much lower value. The effect on isolation performance of having different damping levels in different response regimes is shown to be fairly modest, and is shown to depend on the input excitation level.
Empirical Mode Decomposition for Dynamic AFM Microcantilevers in Air and Liquid Environment
Authors: Kim Il Kwang , Jang Jea Woong , Lee Soo Il
Published: November 2018

The modal decomposition of tapping mode atomic force microscopy microcantilevers in air and liquid environment was experimentally investigated to identify their complex responses. In experiment, the flexible microcantilevers and a flat HOPG sample were used. The responses of the microcantilevers were obtained to extract the linearized modes and orthogonal values using the methods for the proper orthogonal decomposition and the smooth orthogonal decomposition. The influence of the tapping setpoints and the hydrodynamic damping forces were investigated with the multi-mode response of microcantilevers. The results show that the first mode is dominant under normal operating conditions in tapping mode. However, at lower setpoint, the flexible microcantilever behaved uncertain modal distortion near the tip on the sample. The dynamics tapping effect and the damping between microcantilever and liquid influenced their responses.
Voltage Response of Superharmonic Resonance of Electrostatically Actuated MEMS Resonators: Comparison Between Boundary Value Problem Model and Reduced Order Model
Authors: Beatriz Julio , Botello Martin , Caruntu Dumitru I.
Published: November 2018

This paper deals with the voltage response of electrostatically actuated NEMS resonators at superharmonic resonance. In this work a comparison between Boundary Value Problem (BVP) model, and Reduced Order Model (ROM) is conducted for this type of resonance. BVP model is developed from the partial differential equation by replacing the time derivatives with finite differences. So, the partial differential equation is replaced by a sequence of boundary value problems, one for each step in time. Matlab’s function bvp4c is used to numerically integrate the BVPs. ROMs are based on Galerkin procedure and use the mode shapes of the resonator as a basis of functions. Therefore, the partial differential equation is replaced by a system of differential equations in time. The number of the equations in the system is equal to the number of mode shapes (or modes of vibration) used in the ROM. One mode of vibration ROM is solved using the method of multiple scales. Two modes of vibration ROM is numerically integrated using Matlab’s function ode15s in order to obtain time responses, and a continuation and bifurcation analysis is conducted using AUTO 07P. The effects of different nonlinearities in the system on the voltage response are reported. This work shows that BVP model is a valid method to predict the voltage response of a micro/nano cantilevers.
Compact Directional and Frictional Hinges for Flat Folding Applications
Authors: Shemenski Patrick D. , Trease Brian P.
Published: November 2018

Thick-rigid deployable origami structures make use of compliant mechanisms to create folds and hinging surfaces. This paper examines the potential types of compact directional and frictional hinges to supplement the usage of compliant mechanisms in flat-folding applications. Rigid motioncontrolling hinges offer many opportunities to deployable origami. Hinges, in the form of hard stops, ratchets, or spring detents can allow for complex shape generation through kinematic manipulation. Hinged origami lends itself well to the creation of origami robotics, deployable structures, and arrays. With the ability to offer a high packing factor and create a self-supporting deployable structure, further research should be conducted into the application and development of hinged origami.
A Novel Method for Rapid Microfabrication
Authors: Saritas Resul , Al-Ghamdi Majed , Das Taylan , Abdel-Rahman Eihab M.
Published: November 2018

We introduce a novel microfabrication method using direct writing of photoresist with an ultrasonic microplotter equipped. First, the photoresist is driven into the pipette through capillary forces. The pipette is then used to directly write microfeatures on a polydimethylsiloxane (PDMS) substrate. The photoresist is cured on a hot-plate and used as a mold for replication. A second layer of PDMS is cast onto the mold. Once cured on a hot-plate, it is peeled off from the mold to obtain the desired microfeatures. We demonstrate that this method can be used for ultra-rapid and cost-effective fabrication of microchannels (39.65 μm wide) without need for clean room facilities.
Design of Hinge-Line Geometry to Facilitate Non-Plastic Folding in Thin Metallic Origami-Inspired Devices
Authors: Zhang Miaomiao , Trease Brian P.
Published: November 2018

Origami is the traditional art of paper folding, which yields objects that in engineering terms can be considered as mechanisms with relative motion between panels (paper) constrained by hinges (folds). Non-paper materials are often studied for origami-inspired applications in engineering. This article is concerned with material selection appropriate for the hinge function, for which most non-paper materials are lacking either in strength or range of motion. The proposed hinge material of interest is bulk metallic glass (BMG) for its low stiffness, wear and corrosion resistance, biocompatibility, and extreme capacity for elastic deformation. In this paper, panel spacing and geometry are examined to provide insight for designing thin BMG folding membrane hinges that connect larger regions of thicker material (panels). Finite element analysis is performed to study the stress variation, distribution, and displacement along the hinge for several design variations, and several loading profiles are discussed to determine the necessity of modified rounded-edge panels. The results will directly aid in creating origami-inspired designs with membrane hinges and further help with designing devices such as foldable electronics, optical systems, and deployable solar arrays.
Characterization of a Non-Interdigitated Comb Drive
Authors: Gopanchuk Mary , Arabi Mohamed , Nelson-Fitzpatrick N. , Al-Ghamdi Majed S. , Abdel-Rahman Eihab , Yavuz Mustafa
Published: November 2018

This paper reports on the design, fabrication, and characterization of non-interdigitated comb drive actuators in Silicon-on-Insulator (SOI) wafers, using a single mask surface microma-chining process. The response of the actuator is analyzed numerically and experimentally. The results show at the fundamental frequency; it behaves as a longitudinal comb drive actuator. At a higher frequency, it exhibits a high-quality factor which is appropriate for sensor applications.
A New Fabrication Process for Microstructures With High Area-to-Mass Ratios by Stiffness Enhancement
Authors: Ren Zhongjing , Yuan Jianping , Su Xiaoyu , Sun Hao , Galos Richard , Shi Yong
Published: November 2018

A new fabrication process for stiffness-enhanced microstructures with high area-to-mass ratios is presented in this paper. In order to acquire an enhanced stiffness without ruining the structural parameter of area-to-mass ratio, multilayered metallic microstructures are proposed and fabricated by surface and bulk fabrication processes from Micro-Electro-Mechanical Systems (MEMS) technologies. Microstructures based on beams with symmetrically deposited metals are physically built and tested on wafers. A sacrificial silicon layer is used to form gaps between bimetal layers and the microstructures can be deployed vertically when heated due to the effect of thermal mismatch between different materials. The results show a dramatic thickness increase when actuated by Joule heating, and thus a great bending stiffness enhancement.
Multi-Component Topology Optimization for Powder Bed Additive Manufacturing (MTO-A)
Authors: Zhou Yuqing , Nomura Tsuyoshi , Saitou Kazuhiro
Published: November 2018

This paper presents a gradient-based multi-component topology optimization (MTO) method for structures assembled from components made by powder bed additive manufacturing. It is built upon our previous work on the continuously-relaxed MTO framework utilizing the concept of fractional component membership. The previous attempt on the integration of the relaxed MTO framework with additive manufacturing constraints, however, suffered from numerical instability for larger size problems, limiting its application to 2D low-resolution examples. To overcome this difficulty, this paper proposes an improved MTO formulation based on a design field regularization and a nonlinear projection of component membership variables, with a focus on powder bed additive manufacturing. For each component, constraints on the maximum allowable build volume (i.e., length, width, and height), the elimination of enclosed voids, and the minimum printable feature size are imposed during the simultaneous optimization of the overall base topology and component partitioning. The scalability of the new MTO formulation is demonstrated by a few 2D examples with much higher resolution than previously reported, and the first reported 3D example of MTO.
An Engineering Review of the Farm Tractor’s Evolution to a Dominant Design
Authors: Díaz Lankenau Guillermo F. , Winter Amos G.
Published: November 2018

This article explains the origin and performance merits of the conventional farm tractor design, which has endured largely unchanged since the 1940’s. The article covers two main themes: first the historical context and external pressures that directed the farm tractor’s design evolution; and then an analysis on why the tractor’s proportions and force applications points are conducive to good performance. The conventional tractor’s weight distribution, wheel proportions, farming implement attachment, and frame construction are discussed.
Social Force Control for Human-Like Autonomous Driving
Authors: Yoon DoHyun Daniel , Ayalew Beshah
Published: November 2018

An autonomous driving control system that incorporates notions from human-like social driving could facilitate an efficient integration of hybrid traffic where fully autonomous vehicles (AVs) and human operated vehicles (HOVs) are expected to coexist. This paper aims to develop such an autonomous vehicle control model using the social-force concepts, which was originally formulated for modeling the motion of pedestrians in crowds. In this paper, the social force concept is adapted to vehicular traffic where constituent navigation forces are defined as a target force, object forces, and lane forces. Then, nonlinear model predictive control (NMPC) scheme is formulated to mimic the predictive planning behavior of social human drivers where they are considered to optimize the total social force they perceive. The performance of the proposed social force-based autonomous driving control scheme is demonstrated via simulations of an ego-vehicle in multi-lane road scenarios. From adaptive cruise control (ACC) to smooth lane-changing behaviors, the proposed model provided a flexible yet efficient driving control enabling a safe navigation in various situations while maintaining reasonable vehicle dynamics.
Development of a System Model for Low-Cost, Solar-Powered Drip Irrigation Systems in the MENA Region
Authors: Sokol Julia , Grant Fiona , Sheline Carolyn , Winter Amos
Published: November 2018

Drip irrigation has the potential to conserve water and increase crop yields. However, existing drip irrigation systems often require high pumping power, making them financially inaccessible to smallholder farmers. Integrating a holistic system model with a cost-optimization scheme can enable the design and implementation of low-cost, solar-powered drip irrigations systems, ultimately making this technology more cost-effective for smallholder farmers.

This paper describes the algorithms comprising an integrated model of solar-powered drip irrigation systems, consisting of agronomic, hydraulic, pump, and power system modules. It also introduces a preliminary optimization scheme for the power system, which uses the system hydraulics and pump curve to select an optimal solar array and energy storage configuration that minimizes capital cost.

The system model and power system optimization is applied to three case studies, and the resulting power system configurations are compared to outputs from commercially-available software for sizing solar pumping systems. The results show that the model successfully captures the nuances in crop type, local weather patterns, and hydraulic system layout between different cases. This offers a greater level of flexibility than commercially available software, which tends to have broader applications and focuses on larger systems. Future model generations will add more variables to the optimization scheme — including pump selection, variable emitter flow rates and pipe geometries — to provide a versatile design tool for cost-optimized, solar-powered drip irrigation systems.