bluuebunny/crossref_metadata_2025 huggingface dataset:
Classification of Bio-Inspired Periodic Cubic Cellular Materials Based on Compressive Deformation Behaviors of 3D Printed Parts and FE Simulations
Authors: Wang Jun , Rai Rahul
Published: December 2016

Bio-inspired materials have shown to have outstanding mechanical properties over man-made materials and are becoming of increasing interest in many fields of practical applications. Additionally, recent advances in materials and fabrication technologies allow for the design and fabrication of micro- and nano-scale structures to serve as cellular units in macro-scale materials. The mechanical behaviors of cellular solids, including stiffness and strength, can be tuned by simply tailoring the underlying geometry of the structure. In this paper the answer to the following research question is investigated: Can seemingly different bio-inspired geometries of cellular solids result in similar mechanical behaviors? Specifically, the effects of geometry on the compressive deformation responses of multiple bio-inspired periodic cubic cellular structures at macro scale are investigated both through physical tests and FE simulations of 3D printed specimens. The paper outlines standardization of specimens and tests for such a study. Additionally, a $1 recognizer based classification process is used on curves representing compressive deformation behaviors of different bio-inspired geometries to cluster them into same group.
Design Method for Conformal Lattice-Skin Structure Fabricated by AM Technologies
Authors: Tang Yunlong , Yang Sheng , Zhao Yaoyao Fiona
Published: December 2016

Parts with complex geometry can be produced by additive manufacturing processes without a significant increase in fabrication time and cost. One application of AM technologies is to fabricate customized lattice-skin structures which can enhance the functional performance of products with less material and less weight. In this paper, a brief comparison between different types of lattice structures and their related design methods has been done. The result shows that conformal lattice structures may perform better than other types of lattice due to its unique configuration for some design cases. However, most existing design methods of conformal lattice have a limitation to deal with complex external geometry. To solve this issue and fully utilize conformal lattice structures, a general design method for a conformal lattice-skin structure is proposed. This design method consists of two major design stages. At the beginning design stage, conformal surfaces are selected based on proposed general design guidelines. Then two different lattice frame generation methods are provided to generate conformal lattice to fit the selected conformal surfaces. A comparison between these two methods is made to help designers select a suitable method for their design cases. In the second design stage, the thickness of each lattice strut is calculated based on a defined mapping function. This mapping function generally considers two important factors from the result of topology optimization. They are optimal relative density distribution and its related principle stress direction. Based on the calculated strut’s thickness, the geometry model of heterogeneous conformal lattice can be generated. At the end of the design process, skin structures can be added on the generated heterogeneous conformal lattice. To further illustrate and validate the proposed design method, a design case of handle connector is provided. The result of this case study shows this method can provide an efficient tool for designers to generate the conformal lattice-skin structure for a complex external shape.
Multi-Objective Optimization of Virtual Human Motion Posture for Assembly Operation Simulation
Authors: Yang Yunfei , Gu Yan , Fan Xiumin , Cheng Huanchong
Published: December 2016

Mechanical assembly belongs to the last stage of a complete mechanical product manufacturing, which usually involves many manual operations. Virtual assembly can be used to simulate a real product’s assembly process, and to assess the feasibility of the assembly scenario of a product during simulation processes. Virtual human operation simulation is an important part of virtual assembly simulation. In order to improve the fidelity and increase the accuracy of posture simulation for virtual human assembly operation, a multi-objective motion posture optimization scheme for virtual human operation is proposed in the paper. Since the real human body is a complex movement system, the virtual human is modeled as a simplified multi-rigid-body model to decrease complexity. According to ergonomics knowledge and requirements, three elements including joint angle, joint moment and operation field of vision are selected as the criteria to evaluate the virtual human’s motion. These elements are normalized and used for setting the optimization objective of human body assembly operation assessment. Optimal target functions with variables constraints used for the posture optimization problem are constructed in mathematical expression. As there are many rigid-body joint variables, it is difficult to solve the optimization model directly. The optimization model is decomposed according to different joint chains and the operating characteristics of the human body. A multi-objective NSGA-II algorithm is introduced to solve the optimization model, which finally generated a complete and continuous solution of the virtual human assembly operation motion. A case study of an engine connecting rod cap assembly is performed to demonstrate the effectiveness of the proposed optimization method.
A Point-Based Virtual Reality System for Supporting Product Development
Authors: Okamoto Hiroki , Masuda Hiroshi
Published: December 2016

In this paper, we discuss methods to efficiently render stereoscopic scenes of large-scale point-clouds on inexpensive VR systems. Recently, terrestrial laser scanners are significantly improved, and they can easily capture tens of millions points in a short time from large fields, such as engineering plants. If 3D stereoscopic scenes of large-scale point-clouds could be easily rendered using inexpensive devices, they might be involved in casual product development phases. However, it is difficult to render a huge number of points using common PCs, because VR systems require high frame rates to avoid VR sickness. To solve this problem, we introduce an efficient culling method for large-scale point-clouds. In our method, we project all points onto angle-space panoramic images, whose axes are the azimuth and elevation angles of head directions. Then we eliminate occluded and redundant points according to the resolutions of devices. Once visible points are selected, they can be rendered in high frame rates. Visible points are updated when the user stays at a certain position to observe target objects. Since points are processed on image space in our method, preprocessing is very fast. In our experiments, our method could render stereoscopic views of large-scale point-clouds in high frame rates.
Design Education Across Disciplines: Opportunities for Curriculum Advancement
Authors: Nix Anthony A. , Lemke Mark T. , Arlitt Ryan M. , Stone Robert B.
Published: December 2016

Design education is a large field. It is not just limited to engineering design but can also include apparel design, industrial design, graphic design, architecture, and many others. These disciplines instruct students to follow a similar design process to what is generally taught in engineering design. However, these other disciplines contain a variety of instructional techniques, class structures, and class types that are not regularly included in engineering design. While design engineers tend to get a background rich in math and science, instructing students in design can be difficult. Many of these math and science classes focus on one approach and one right answer. However, in design the answers tend to fall on a spectrum from unsatisfactory to varying levels of satisfactory to ideal and innovative solutions, all of which can be uncovered using widely varying design methods. Despite the rigidness of the mechanical engineering curriculum there are areas where the implementation of techniques used in the other design disciplines could be advantageous to help engineering design students improve students design skills, design process knowledge, and softer skills such as team communication. The research done in this paper examines how the curricula of design disciplines could influence the coursework of students focusing on the design area of mechanical engineering.
Learning Human Search Strategies From a Crowdsourcing Game
Authors: Sexton Thurston , Ren Max Yi
Published: December 2016

There is evidence that humans can be more efficient than existing algorithms at searching for good solutions in high-dimensional and non-convex design or control spaces, potentially due to our prior knowledge and learning capability. This work attempts to quantify the search strategy of human beings to enhance a Bayesian optimization (BO) algorithm for an optimal design and control problem. We consider the sequence of human solutions as generated from BO, and propose to recover the algorithmic parameters of BO by maximizing the likelihood of the observed solution path. The method is different from inverse reinforcement learning (where an optimal control solution is learned based on human demonstrations) in that the latter requires near-optimal solutions from humans, while we only require the existence of a good search strategy. The method is first verified through simulation studies and then applied to the human solutions crowdsourced through a gamification of the problem under study [1]. We learn BO parameters from a player with a demonstrated good search strategy and show that applying the BO algorithm with these parameters to the game noticeably improves the convergence of the search from using a default BO setting.
Operation Modes Comparison of a Reconfigurable 3-PRS Parallel Manipulator Based on Kinematic Performance
Authors: Maraje Siddharth , Nurahmi Latifah , Caro Stéphane
Published: December 2016

The 3-PRS parallel manipulator with different arrangements of prismatic joints is called a reconfigurable 3-PRS parallel manipulator in this paper. The three prismatic joints in PRS limbs are attached to the base with an angle α between the horizontal plane of the base and their directions. Based on [1], the manipulator has identical operation modes, namely x0 = 0 and x3 = 0 for any value of α. Accordingly, this paper presents in more details the performance evaluation of these operation modes by using the output transmission index (OTI) and the constraint transmission index (CTI). The OTI and CTI determine the force transmission efficiency and the constraining ability of the manipulators, respectively.

Initially, the determination of the number and types of operation modes of the 3-PRS parallel manipulator is recalled. The computation is carried out by using an algebraic approach, namely the Study kinematic mapping. In each operation mode, the actuation wrenches and the constraint wrenches are obtained based on the Screw theory. Then, the OTI and CTI are traced in the orientation workspace of the manipulator for different values of angle α. Furthermore, the singularity conditions are analysed corresponding to the values of OTI and CTI.
Nonlinear-Based Switch Triggered by Gas Using Electrostatically Actuated Microbeams
Authors: Bouchaala Adam , Jaber Nizar , Yassine Omar , Shekhah Osama , Eddaoudi Mohamed , Younis Mohammad I.
Published: December 2016

The objective of this paper is to demonstrate the integration of a MOF thin film on electrostatically actuated microstructures to realize a switch triggered by gas and a sensing algorithm based on amplitude tracking. The devices are based on the nonlinear response of micromachined clamped-clamped beams. The microbeams are coated with a Metal-Organic Framework (MOF), namely HKUST-1 to achieve high sensitivity. The softening and hardening nonlinear behaviors of the microbeams are exploited to demonstrate the ideas. For gas sensing, an amplitude-based tracking algorithm is developed to quantify the captured quantity of gas. Then, a MEMS switch triggered by gas using the nonlinear response of the microbeam is demonstrated. Noise analysis is conducted, which shows that the switch has high stability against thermal noise. The proposed switch is promising for delivering binary sensing information, and also can be used directly to activate useful functionalities, such as alarming.
An Integrated Approach to Automated Synthesis, Simulation and Optimization of Energy and Signal-Based Design Concepts
Authors: Münzer Clemens , Shea Kristina
Published: December 2016

Computers have the capability to support human designers in a variety of tasks including releasing the human designer from routine tasks via design automation as well as sparking and supporting innovation and creativity. To support the concept phase effectively, a wide range of possible concepts, which are quantitatively evaluated, should be considered to enable designers to explore the solution space and choose advantageous concepts. To enable automated solution space exploration and evaluation, this research presents a method that uses automated model transformations based on a graph-based object-oriented knowledge representation. The approach combines previous research with automated generation of variable assignments for generated concepts and optimization using simulated annealing. The variable assignments are generated by automatically setting up and solving constraint satisfaction problems and evaluated using automatically generated simulation models. The main contributions of this research are an integrated and fully automated approach starting with task definition and ending with a solution space of optimized product concepts and generic model transformations that enable automated use of Boolean satisfiability, constraint satisfaction and bond graph-based simulation methods. The method is validated on the case studies of automotive powertrains.
Frequency Control of Light-Activated Shape Memory Polymer Laminated Beams: Characterization and Experiments
Authors: Li Huiyu , Zhang Xufang , Tzou Hornsen
Published: December 2016

Light-activated shape memory polymers (LaSMPs) exhibit stiffness variations when exposed to ultraviolet (UV) lights. Thus, LaSMP could manipulate structural natural frequencies with UV light exposures when laminated on structures. This study aims to experimentally demonstrate the effectiveness of LaSMP frequency control of a flexible beam. The natural frequency of a three-layered Euler-Bernoulli beam composed of LaSMP, adhesive tape and the flexible beam is analyzed and its frequency formulation exhibits the LaSMP stiffness influence. As the LaSMP adopted in this study is a new spiropyran based composition, a generic Young’s modulus model is proposed and then simplified to model the present LaSMP composition. To make sure the experiment is carried out in a homogenous light field, the light intensities of the UV surface light source at different positions are tested. The temperature change of the LaSMP sample under UV exposures is also measured. The time constant of the reverse reaction and the threshold intensity of the reverse reaction are measured. LaSMP Young’s modulus variation is tested with a uniaxial tension experiment. The constitutive model of LaSMP’s Young’s modulus is validated by experimental data. With these preparations, the LaSMP laminated flexible beam model is exposed to the UV lights and its natural frequencies are identified with a data acquisition and analysis system. The maximum natural frequency variation ratio achieves 5.67%. Comparing both theoretical and experimental data of natural frequency control, this study also validates the LaSMP Young’s modulus constitutive model.
Effect of the Deformation of the Supporting Structure on the Measurement of the Inertia Properties of Vehicles
Authors: Previati Giorgio , Gobbi Massimiliano , Ballo Federico
Published: December 2016

In the measurement of the inertia properties of rigid bodies (mass, centre of gravity location and inertia tensor) the structures carrying the body under test are usually considered to be rigid. This assumption is less and less satisfied as the dimensions of the body grow. Consequently, the forces exchanged between the body and the structures can be large enough to deform the structure and affect the measurement, especially the location of the centre of gravity.

In this paper, with special reference to the InTenso+ Measuring System of the Politecnico di Milano, the effects of the deformation of the test rig structure when measuring large bodies is investigated. A theoretical analysis is performed by using a flexible multibody mathematical model of the test rig. The deformation of the test rig is deeply investigated by a dedicated FEM model. The results of the theoretical analysis are then validated by measuring the inertia properties of a light truck.

It turns out that the deformation of the test rig can actually affect the measurement. This deformation can be compensated by a proper mathematical procedure. The method can, consequently, be employed also for very large bodies for which the construction of a sufficiently rigid structure as to neglect its deformation is practically impossible.
Estimating Stress Bounds in Early-Stage Design of Distributed Compliant Mechanisms
Authors: Patiballa Sreekalyan , Shanley John Francis , Krishnan Girish
Published: December 2016

Synthesis of distributed compliant mechanisms is often a two-stage process involving (a) conceptual topology synthesis, and a subsequent (b) refinement stage to meet stress and manufacturing specifications. The usefulness of a solution is ascertained only after the sequential completion of these two steps, which are in general computationally intensive. This paper presents a strategy to rapidly estimate final operating stresses even before the actual refinement process. This strategy is based on the uniform stress distribution metric, and a functional characterization of the different members that constitute the compliant mechanism topology. It enables selecting the best conceptual solution for further optimization, thus maximally avoiding refinement of topologies that inherently may not meet the stress constraints. Furthermore this strategy enables modifying topologies at the early design stage to meet final stress specifications, thus greatly accelerating the overall synthesis process.
Initially Imperfect MEMS Microplates Under Electrostatic Actuation: Theory and Experiment
Authors: Saghir Shahid , Bellaredj Mohammed L. , Younis Mohammad I.
Published: December 2016

Microplates are building blocks of many Micro-Electro-Mechanical Systems (MEMS). It is common for them to undergo imperfections due to residual stresses caused by the micro fabrication process. Such plates are essentially different from perfectly flat plates and cannot be modeled using the governing equations of flat plates. In this article, we adopt the governing equations of imperfect plates employing the modified von-Karman strains. These equations then are used to develop a Reduced Order Model based on the Galerkin procedure to simulate the static and dynamic behavior of an electrostatically actuated microplate. Also, microplates made of silicon nitride are fabricated and tested. First, the static behaviour of the microplate is investigated when applying a static voltage Vdc. To study the dynamic behaviour we apply a harmonic voltage, Vac, superimposed to Vdc. Simulation results show good agreement with the experimentally measured responses.
Vehicle Ride Evaluation on a Four-Post Rig: Is the Vertical Seat Component Sufficient?
Authors: Kat Cor-Jacques , Mendez Esteban , Els Pieter Schalk , Dhaens Miguel
Published: December 2016

Ride has always been an important aspect in vehicle design, driven by the customer’s increasing demand for vehicles with better comfort. The vibrational response of the vehicle is one of many factors contributing to the overall ride perception, with road inputs being the major excitation source. The improved capabilities of vehicle simulation models and virtual proving grounds have supplemented experimental prototype testing for tuning suspensions. Final tuning, and ride evaluation, is however still done through physical on-road testing. Four-post rig tests hold potential cost and time savings when used appropriately in the development process.

The four-post rig imposes only vertical inputs at the tire contact patches and thus it is expected for the vertical response of the vehicle to be the dominant component. The objective of this paper is to determine whether ride comfort can sufficiently be evaluated on the four-post rig using only the vertical seat Component Ride Value (CRV). The response of an instrumented vehicle on the four-post rig was measured by a tri-axial seat pad accelerometer. Vertical, longitudinal and lateral seat CRVs as well as the seat Point Ride Value (PRV) were calculated from the measured seat acceleration in the three translational directions using the BS6841 (1987) standard. The PRV is the square root of the sums of squares of the three CRVs. The CRVs and PRV, obtained from tests at various speeds and road roughnesses, were analyzed to determine whether the vertical seat CRV is sufficient in capturing the perceived ride comfort.

Results showed that the longitudinal and lateral CRVs are in excess of 26% and 63%, respectively of the dominant vertical seat CRV over the various tests. This implies that the vertical seat CRV underestimated the discomfort when compared to the seat PRV. It was also observed that the three CRVs had different sensitivities to test parameters and conditions. For example, at different speeds over the same road roughness the longitudinal CRV increased significantly more than the other two components. The differences in sensitivities may be due to the specific boundary conditions imposed on the vehicle by the four-post rig. It is concluded that the vertical seat CRV may not be sufficient to evaluate the ride comfort on a four-post rig.
A Hyperheuristic Approach to Leveraging Domain Knowledge in Multi-Objective Evolutionary Algorithms
Authors: Hitomi Nozomi , Selva Daniel
Published: December 2016

Evolutionary algorithms have shown much success in solving real-world design problems, but they are considered computationally inefficient because they rely on many objective-function evaluations instead of leveraging domain knowledge to guide the optimization. An evolutionary algorithm’s performance can be improved by utilizing operators called domain-specific heuristics that incorporate domain knowledge, but existing knowledge-intensive algorithms utilize one or two domain-specific heuristics, which limits the amount of incorporated knowledge or treats all knowledge as equally effective. We propose a hyperheuristic approach that efficiently utilizes multiple domain-specific heuristics that incorporate knowledge from different sources by allocating computational resources to the effective ones. Furthermore, a hyperheuristic allows the simultaneous use of conventional evolutionary operators that assist in escaping local optima. This paper empirically demonstrates the efficacy of the proposed hyperheuristic approach on a multi-objective design problem for an Earth observation satellite system. Results show that the hyperheuristic approach significantly improves the search performance compared to an evolutionary algorithm that does not use any domain knowledge.
Virtual Acoustic Model for the Simulation of Passing Vehicle Noise
Authors: Siegel Antje , Weber Christian , Mahboob Atif , Albers Albert , Landes David , Behrendt Matthias
Published: December 2016

In this paper a virtual acoustic model for the simulation of noise by passing vehicles is described. The underlying motivation for the acoustic model is the increasing demand for realistic traffic and acoustic disturbance simulation methods. For this purpose, simulation tools are desired, that allow simulation of different kinds of traffic scenarios within a Virtual Reality (VR) environment. This includes a plausible and realistic presentation of the acoustic situation. The virtual vehicle model introduced in this paper is composed of several individual sound sources, e.g. for the tires, the engine and the exhaust system. Each sound source has its own directional characteristics. These characteristics are considered by sets of digital filters for each sound source. For that purpose, measurement series with a car on a dynamometer were performed.

Furthermore, in order to consider the environmental conditions a method for the description of sound reflections at simple objects (e.g. plane walls) is explained in this paper. The implemented concept offers the possibility to create individual mirror sources for every initial sound source and every object that can cause reflections. Since the concept is intended for the interactive application, the described method works in real time.

In order to evaluate the described virtual acoustic model, a test with volunteers was performed. These examinations are also described and discussed in this paper.
On the Thermomechanical Behavior of Ni60Ti40 Coupons via High Performance Full Field Experiments
Authors: Iliopoulos Athanasios P. , Steuben John C. , Michopoulos John G. , Baxevanis Theocharis , Kirk Tanner , Lagoudas Dimitris C.
Published: December 2016

Emerging applications for shape memory alloys, such as actuation and energy absorption devices, require better understanding of the mechanics and failure behaviors associated with these materials. In this paper we study the inelastic response of a NiTi alloy under combined thermomechanical actuation. In particular, failure due to strains generated by cooling under isobaric and isothermal conditions is investigated. Strain measurements are performed using a new technique known as Direct Strain Imaging, which provides full field strains of both higher accuracy and higher spatial resolution than previously achievable. The experimental data support the conclusion that the type of fracture observed may be attributed to stress redistribution, caused by a phase transformation.
A Single Input-Multiple Output Curve Adaptive Linkage Array
Authors: Moosavian Amin , Sun Cong Zhu (John) , Xi Fengfeng (Jeff) , Inman Daniel J.
Published: December 2016

Development of morphing systems is a fast evolving area of research with broad applications, including morphing aircraft. Classified based on the magnitude of the motion, there are generally two scales of morphing: local (small scale; e.g. airfoil morphing), and global (large scale; e.g. wing morphing), both requiring adaptive structures to provide morphing motion while maintaining structural rigidity. In this paper, a new design is presented for local morphing, inspired by the notion of minimal actuation effort. Based on the concept of multi-loop linkages, this design allows a morphing curve, represented by a series of points, to take up three distinct shapes, with a single actuation input. The underlying design is based on a network of four-bar linkages connected together to form a multi-loop linkage, referred to as the Curve Adaptive Linkage Array (CALA). A three-step method is developed and presented here to find the geometric dimensions of the CALA. Furthermore, a case-study for an airfoil morphing application is presented and solved using the proposed method. The presented method provides a means to reduce the number of actuators needed for shape morphing, and is generally applicable to any shape morphing application.
Modeling and Analysis of Beam Flexure Based Double Parallel Guiding Mechanisms: A Modified Pseudo-Rigid-Body Approach
Authors: Liu Pengbo , Yan Peng
Published: December 2016

In the present paper, we take the complaint double parallel guiding mechanism as a particular case study to investigate a modified pseudo-rigid-body (MPRB) modeling approach for beam flexure based mechanisms by considering the nonlinear effects of the center-shift and the load-stiffening. In particular, through incorporating the elastic stretch of the beam flexure into the linear Bernoulli-Euler equation, a more accurate model of the beam flexure is derived. Accordingly an MPRB model for a beam flexure is established, which consists of two rigid links joined at a revolute joint and a torsional spring along the beam. Different from traditional PRB model, the location of the torsion spring is not only determined by the characteristic radius factor, but also a purely elastic stretch under the action of the axial force. Meanwhile, both the characteristic radius factor and the equivalent stiffness of the beam flexure are no longer constant values, but affected by the applied general tip load, especially the axial force. Based on the analysis results of a beam flexure, we obtain a more accurate model of the double parallel guiding mechanisms, which is further verified by the finite element analysis (FEA) results. The proposed MPRB model provides a more parametric method to predict the performance characteristics such as deformation capability, stiffness variation, as well as error motions of the beam flexure based complaint mechanisms, and offers a new look into the design and optimization of beam-based compliant mechanisms.
Design of Mechanism and Preliminary Field Validation of Low-Cost Transfemoral Rotator for Use in the Developing World
Authors: Cavuto Matthew L. , Chun Matthew , Kelsall Nora , Baranov Karl , Durgin Keriann , Zhou Michelle , Arelekatti V. N. Murthy , Winter Amos G.
Published: December 2016

Transfemoral (above-knee) amputees face a unique and challenging set of restrictions to movement and function. Most notably, they are unable to medially rotate their lower-leg and subsequently cross their legs. The best and most common solution to this issue today is a transfemoral rotator, which allows medial rotation of the leg distal to the knee through a lockable turntable mechanism. However, currently available transfemoral rotators can cost thousands of dollars, and few equivalent technologies exist in the developing world. This paper, supported by the results of field studies and user testing, establishes a framework for the design of a low-cost and easily manufacturable transfemoral rotator for use in the developing world. Two prototypes are presented, each with a unique internal locking mechanism and form. A preliminary field study was conducted on six transfemoral amputees in India and qualitative user and prosthetist feedback was collected. Both prototypes successfully allowed all subjects to complete tasks such as crossing legs, putting on pants, and tying shoes while maintaining functionality of walking and standing. Future iterations of the mechanism will be guided by a combination of the most positively received features of the prototypes and general feedback suggestions from the users.
Exploiting a Tail Fin to Improve the Performance of Galloping Flow Energy Harvesters
Authors: Noel James H. , Daqaq Mohammed F.
Published: December 2016

Flow energy harvesters (FEHs) have recently emerged as a major player in the field of micro-power generation. Such devices are designed to harness energy from a dynamic flow field, typically wind, in order to power remote, sub-milliwatt consumption sensors that are hard to access or maintain. Previous research efforts have focused on harnessing flow energy under nearly steady conditions where measurable variations in the flow speed occur at a much longer time scale than the time constant of the harvester itself. Under such conditions, the nature of the harvester’s transient response is irrelevant and does not constitute a critical performance criterion. However, since gusts of wind also contain a significant amount of energy, designing FEHs to have a fast transient response is essential to capture the maximum possible energy from the flow. To address this critical issue, we propose a galloping piezoelectric energy harvester consisting of piezoelectric cantilever beam with a modified bluff body mounted at its tip. Square, trapezoid, and triangle bluff bodies were tested, each augmented with a tail fin to enhance the transient response of the harvester. It is shown experimentally that the settling time of the response and the steady state output power can be improved substantially when the fin is added.
A Single-DoF Self-Regulated Gravity Balancer for Adjustable Payload
Authors: Chu Yu-Lin , Kuo Chin-Hsing
Published: December 2016

This paper presents a single-degree-of-freedom (single-DoF) gravity balancer that can deal with variable payloads. The proposed design is made of a standard spring-based statically-balanced mechanism and a spring adjusting mechanism. The installation points of the balancing spring are controlled by two cables. When the payload is applied, the spring adjusting mechanism will drive the two cables to regulate the spring installation points to suitable locations for balancing purpose. The significant novelty of the proposed design is that the balancer can sense the change of the payload and then automatically regular its spring attachment, which are all done by pure mechanical solution, i.e., with no electrical sensor or actuator. A prototype is built up to test the proposed design.
Deriving Infill Design of Fused Deposition Modelled Parts From Predicted Stress Profiles
Authors: Gopsill James A. , Hicks Ben J.
Published: December 2016

The use of Fused Deposition Modelling (FDM) is increasing rapidly in both the commercial and industrial sectors as a means of rapidly prototyping geometrically complex parts. Particular affordances of FDM include the reduction of waste material during manufacture, the use of multiple materials within a single manufacturing process and the ability to manipulate the internal geometry of a part. The latter of which has seen the generation of many 2-dimensional repeating pattern structures such as square, rectilinear and hexagonal, as well as an emerging field of 3-dimensional structures. Although these patterns have provided stiffness and rigidity whilst reducing the production time of FDM prototypes, many do not consider the actual loading conditions of the part in-situ, where it is argued that further significant gains in the performance could be achieved. This includes further reduction in process time and increased part functionality.

Thus, this paper presents initial work into the generation of an infill that is derived from the predicted stress profile for the part. This has been achieved through the post-processing of Finite Element (FE) models to identify the stress profile. Interpolation across these profiles leads to a set of aligned Bézier splines that enable the transmission of force and are also able to be manufactured using FDM. These splines are embedded within the typical slicing procedure of a part ahead of being manufactured on a FDM machine. Initial results from parts designed to support three-point bending loads show a 79% increase in the stiffness of the part alongside a consistent and repeatable mode of failure when compared to the commonly used honeycomb infill design.
Hygroscopic Swelling Behavior of 3D Printed Parts due to Changes in Environmental Conditions
Authors: Park Ju-young , Ha Sangho , Park Eunju , Kwon Daeil , Kim Namhun
Published: December 2016

Selective laser sintering (SLS) printers have been used for rapid prototyping, and the prototypes of part assemblies have been reported to expand or shrink over time. This paper examines the hygroscopic swelling behavior of 3D printed parts from SLS printers. A total of 10 hexahedron samples were produced using nylon-12, which is a common material used for prototyping. Half of the samples were exposed to a high temperature to reduce the moisture content, and the rest were left at a room temperature. In the meantime, 13 dimensions of each sample were measured periodically along with the local weather records including relative humidity in order to track the hygroscopic swelling behavior of the samples. The results showed that the deformation was mostly occurred to the dimensions parallel to the sintering layers. Also, changes in these dimensions were found to have a high correlation with the relative humidity regardless of temperature conditions. These results imply that changes in environmental conditions such as relative humidity result in the deformation of 3D printed parts after production. The high correlation between dimension change and relative humidity also indicates the layup orientation is a decisive factor to predict the deformation of 3D printed parts. Thus, unexpected deformation of 3D printed parts can be avoided by optimizing the parts design considering the layup orientation and by controlling the environmental conditions.
Compliant Mechanism Design Through Topology Optimization Using Pseudo-Rigid-Body Models
Authors: Kalpathy Venkiteswaran Venkatasubramanian , Turkkan Omer Anil , Su Hai-Jun
Published: December 2016

The initial design of compliant mechanisms for a specific application can be a challenging task. This paper introduces a topology optimization approach for planar mechanisms based on graph theory. It utilizes pseudo-rigid-body models, which allow the kinetostatic equations to be represented as nonlinear algebraic equations. This reduces the complexity of the system compared to beam theory or finite element methods, and has the ability to incorporate large deformations. Integer variables are used for developing the adjacency matrix, which is optimized by a genetic algorithm. Dynamic penalty functions describe the general and case-specific constraints. A symmetric 3R model is used to represent the beams in the mechanism. The design space is divided into rectangular segments while kinematic and static equations are derived using kinematic loops. The effectiveness of the approach is demonstrated with the example of an inverter mechanism. The results are compared against finite element methods to prove the validity of the new model as well as the accuracy of the approach outlined here. Future implementations of this method will include stress and deformation analysis and also introduce multi-material designs using different pseudo-rigid-body models.
Feasibility of a Clutchless Dual-Shaft Hybrid Transmission System for Performance Applications
Authors: Shah Sahil , Prost Victor , Eubanks Zachary , Reiter Paige , Bondarchuk Daria , Hua Yu , Dorsch Daniel S. , Winter Amos G.
Published: December 2016

A novel hybrid-electric transmission concept was sought that yields higher acceleration and smoother gear-shifts compared to existing dual-clutch systems while improving the energy efficiency of the vehicle. After evaluating a range of strategies, the elimination of the clutch was identified as a viable method for reducing the vehicle’s effective inertia and viscous losses. The proposed architecture implements a single electric motor, and two separate shafts for odd and even gears, to replace the functions of a clutch. High acceleration rates can be achieved using the electric motor when launching the vehicle. Furthermore, the torque from the electric motor (EM) and internal combustion engine (ICE) can be simultaneously delivered through the two shafts to sustain this high acceleration. A 0 to 100 km/hr time of 3.18 s was simulated for a 1600 kg vehicle using a 180 kW EM and 425 kW ICE. In addition, the EM can be used to match the speeds of consecutive gears on the two shafts to reduce jerk while shifting. Shift durations were found to vary between 0.2 and 0.9 s using this strategy. Other benefits include regenerative braking and the removal of the reverse gear since the EM can rotate in either direction. It was also found that the vehicle can be operated on only electric power in urban settings — represented by the NEDC driving cycle — if the battery is recharged through regenerative braking, and by the ICE the vehicle is stopped.
Optimization of Energy Use Strategies in Building Clusters Using Pareto Bands
Authors: Odonkor Philip , Lewis Kemper
Published: December 2016

Optimization research on operational strategies of energy use in building clusters have generally marginalized the effects of uncertainty in favor of reduced computational expense. This however leads to a significant disconnect between the expected energy cost and the average cost observed under uncertainty. Bridging this divide requires the incorporation of uncertainty analysis which poses both technical and computational challenges. This paper addresses these challenges through the notion of a Pareto band, demonstrating its applicability towards developing resilient operational strategies in a timely and computationally efficient manner. Under the proposed approach, Monte Carlo simulations are leveraged to reveal an envelope of optimality contained within the energy cost solution space. This optimality envelope, formally introduced as a Pareto band, is then used to train generalized linear models (GLMs) enabling robust operational strategy predictions. The results obtained from this approach highlight significant improvements in energy cost performance under uncertainty.
Development of a Manufacturing Ontology for Functionally Graded Materials
Authors: Furini Francesco , Rai Rahul , Smith Barry , Colombo Giorgio , Krovi Venkat
Published: December 2016

The development of manufacturing technologies for new materials involves the generation of large and continually evolving volumes of data. The analysis, integration and management of these data, typically stored in multiple independently developed databases, creates significant challenges for practitioners. Strategies which allow open sharing of pre-competitive data pertaining to engineering design can play a powerful role in enabling innovation, but these strategies can work only if the data themselves can be presented in a way that is both consistent and understandable to both humans and computers.

We believe that ontology applied to engineering (OE) represents a viable strategy for the alignment, reconciliation and integration of diverse and disparate data. The scope of OE includes: consistent capture of knowledge pertaining to the types of entities involved; facilitation of cooperation among diverse groups of experts; effective and flexible ongoing curation and update of data; and collaborative design and knowledge reuse.

We propose as case study an ontology for the domain of composite materials focusing in particular on the class of ‘Functionally Graded Materials’ (FGM) with examples drawn from the field of biomedical applications. The goal of the ontology is to provide information about the components of such materials, the manufacturing processes involved in their creation, and their applications, ranging from additive manufacturing to restorative dentistry. The ontology is developed using Basic Formal Ontology (BFO) and parts of the Ontology for Biomedical Investigation (OBI) and follows the best practice principles for ontology development codified in the OBO (Open Biomedical Ontologies) Foundry.
Effect of Surface Roughness in Micro Injection Moulding Process of Thin Cavities
Authors: Bellantone Vincenzo , Surace Rossella , Modica Francesco , Fassi Irene
Published: December 2016

Due to its ability to produce low-cost and high repeatable micro polymeric parts, injection moulding of micro components is emerging as one of the most promising enabling technologies for the manufacturing of polymeric micro-parts in in many different fields, from IT to Healthcare, to Medicine.

However, when approaching the micro-scale, different issues related to the process should be addressed, especially as the depth of the mould cavity becomes very thin. In particular, the mould roughness could affect the surface quality of the produced micro components, like in macro moulding, as well as the complete filling of the parts. Although micro-injection moulding process has been extensively studied, further research on the effect of mould roughness conditions and on non-Newtonian fluid flow in micro-cavities are required. This will shed a light and open up new paths for a deeper understanding of the moulding scenario.

The main objective of the present paper is the evaluation of the influence of the mould roughness on the polymer flow during micro injection moulding process. The test parts have been realized in POM material and have thickness lower than 250 μm. The test part design has been properly conceived in order to neglect the effect of dimensions and geometry and to highlight the roughness contribution during the filling phase of micro injection moulding process. The experimentation has been performed considering cavities with different roughness values (3 levels) and decreasing depths (3 levels), for a total of nine test parts manufactured by micro-electrical discharge machining process (μ-EDM).

The results of the experiments are discussed in the paper and show that cavity surface roughness affects the injection process as the moulding scale level is decreased. In particular, when the cavity depths are reduced, higher surface roughness promotes the filling of components and this finding could be ascribed to the increase of wall slip effect.
Construction and Control of Surfaces via Deployable Mechanisms With Three Degrees of Freedom
Authors: Lu Shengnan , Ramadoss Vishal , Zlatanov Dimiter , Ding Xilun , Zoppi Matteo
Published: December 2016

Applications of deployable mechanisms can be found in aeronautic and civil engineering, often in the creation of unfolding large-scale structures with curved surfaces. This paper proposes novel mechanical networks, which are used to approximate three-dimensional surfaces, such as cuboids, ellipsoids, or hyperboloids. Each such deployable structure is assembled from unit Sarrus and scissor linkages of different sizes, has several decoupled degrees of freedom, and can take any shape within a different family of parameterized surfaces. Each degree of freedom controls a separate parameter in the equation describing the physical boundary of the linkage network. The size and placement of the unit linkages and their elements are analyzed and selected for obtaining the expected families of surfaces. CAD models and kinematic simulations demonstrate the abilities of the mechanisms to perform dynamically the desired approximation.
An Approach to Sorting Swarm Robots to Optimize Performance
Authors: Shang Beining , Crowder Richard M. , Zauner Klaus-Peter
Published: December 2016

Swarm robotic systems can offer many advantages including robustness, flexibility and scalability. However one of the issues relating to overall swarm performance that needs to be considered is hardware variations inherent in the implementation of individual swarm robots. This variation can bring behavioral diversity within the swarm, resulting in uncontrollable swarm behaviors, low efficiency, etc. If swarm robots could be separated by behaviors, operational advantages could be obtained. In this paper we report an approach to the sorting of large robotic swarms using an approach inspired by chromatography. Hence the tedious and expensive calibration process can be avoided. The results investigate the influence of the internal control parameters, together with environmental effects on the robotic behavioral sorting. We concluded that if the robot has knowledge of previous events coupled with a specific arena pattern density will offer improved behavioral sorting.