bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental Investigation of the Flow Inside the Rotor Passage of an Axial Ventricular Assist Device
Authors: Chen Huang , Drešar Primož , Lynch Bryan , Sharma Paarth , Williams Christopher , Katz Joseph
Published: November 2019

Ventricular assist devices (VAD) are designed to provide circulatory support to patients suffering from advanced-stage heart failure. While not pulsatile, the advantages of continuous axial flow VADs include a compact size and low mechanical failure rate. However, being compact, they operate at high speed, resulting in adverse effects, such as hemolysis caused by high flow shear and thrombosis formation in stagnant regions are common and threaten the successful use of the device. While state-of-the-art computational fluid dynamics (CFD) is widely used in designing these devices, detailed high-resolution experimental measurements of the flow within them are not readily available in the literature. Such experimental data is crucial for understanding the flow inside the VAD and its interaction with blood cells as well as for validating the CFD predictions. The present study investigates the flow inside a 1:1 exact replica of a VAD – ReliantHeart HeartAssist5®. This 12mm diameter device consists of an inlet guide vane (IGV), a rotor and a stator. However, unlike in the real machine, the rotor is driven by a thin shaft that penetrates through the center of the IGV. Refractive index-matching is used to facilitate optical measurements. Hence, all the blades and housing of the pump are made of transparent acrylic. The working fluid is a mixture of water, sodium iodide and glycerin, which matches the refractive index of acrylic, and the kinematic viscosity of blood. Performance tests have been carried out at speeds ranging from 7000 to 9000 RPM. Trends of the results are consistent with those of the actual machine. While scaled data for the pressure rise across the rotor at different speeds collapse, the total head rise across the entire machine does not. High-resolution 2D PIV measurements with vector spacing of 30μm have been conducted in meridional planes of the rotor passage at several blade orientations. They have been performed at 8000RPM and flowrate of 4.5L/min, consistent with physiological requirements. They show that near the rotor front end, the flow in the tip region is dominated by the tip leakage vortex (TLV), associated blockage effects, and very high turbulence level. The upstream end of this domain remains aligned with the leading edge, implying that blades persistently dissect the remnants of a previous TLVs. Interaction of the hub boundary layer with the blades also generates secondary flows. Downstream of the helical section of the rotor, the axial flow is high near the hub and low in the outer part of the passage due to leakage flow-related blockage. Hub boundary layer separation occurs upstream of the stator, generating a large circumferential vortex that occupies nearly half of the rotor span. The complexity of the flow structure and turbulence in this machine would be a challenge to model.
Research and Design of In-Arm Torsional Electromagnetic Active Suspension
Authors: Han Chengleng , Xu Lin , Abdelkareem Mohamed A. A. , Cui Enkang , Zou Junyi , Rono Kipkorir , Zhao Zhen , Yang Bo
Published: November 2019

This paper introduced a new type of an active suspension named as In-Arm Torsional Electromagnetic Active Suspension (ITEAS) according to its suspension characteristics. The proposed ITEAS is capable of actively controlling body attitude and adjusting the stiffness and damping of a suspension system in a larger scale. The structure of the ITEAS system is composing of a mechanical displacement adjustment device, a two-chamber vane damper connected by an electromagnetic valve, two torsion bars and necessary connection units such as trailing arms. Based on the hydraulic theory and fluid mechanics, the mathematical model of the vane damper was established and the external characteristic curve of the damper was obtained through the simulations. Regarding to the ITEAS stiffness and damping analysis, a quarter dynamic vehicle model was established and simulated by the AMESim platform. The results showed that the automobile ride based on the ITEAS system was reasonable as well as the functions of body height adjustment and suspension controllability were available. Thereafter, a small-scale prototype has been built to calibrate the unknown parameters for further research on ITEAS.
Topological Reconfigurations Based on a Concatenation of Bennett and RPRP Mechanisms
Authors: Hsu Kuan-Lun , Ting Kwun-Lon
Published: November 2019

This paper presents a family of over-constrained mechanisms with revolute and prismatic joints. They are constructed by concatenating a Bennett 4R and a spatial RPRP mechanism. This is a major breakthrough because an assembly of two different source-modules, for the first time, will be used in the modular construction. A Bennett 4R mechanism and a spatial RPRP mechanism are mated for the purpose of demonstration. Topological reconfigurations of synthesized mechanisms are also discussed. The results indicate that synthesized mechanisms can be topologically reconfigured with either a plane-symmetric structure or a spatial four-bar RCRC loop. These synthesized mechanisms along with their reconfigurations represent the first and unique contribution in theoretical and applied kinematics. Academically, proposed methodology can be used to synthesize several families of over-constrained mechanisms. Each family of new mechanisms is unique and has its own academic significance because they are theoretical exceptions outside Chebychev–Grübler–Kutzbach criterion. The geometrical principles that address the combination of hybrid loops can treat the topological synthesis of over-constrained mechanisms as a systematic approach instead of a random search. Industrially, such paradoxical mechanisms could also be potentially valuable. The ambiguity of their structural synthesis stops ones from being aware of these theoretical exceptions. Hence, people fail to implement these mechanisms into real-world applications. The findings of this research can help people sufficiently acquire the knowledge of how to configure such mechanisms with desired mobility. From a practical point of view, over-constrained mechanisms can transmit motions with less number of links than the general types need. This means that engineers could achieve a compact design with fewer components. These features could be an attractive advantage to real world applications.
Design of Multi-DOF Spherical Piezoelectric Motor Using Electrode Configuration Based Actuating Units
Authors: Lin Chi-Ying , Sung Yu-Ting , Huang Yu-Hsi
Published: November 2019

Spherical piezoelectric motors (SPMs) apply piezoelectric materials as stators to generate modal responses for rotor orientation. The SPMs have the advantages of simple structure and compact size but may suffer from the difficulty of orientation manipulation. This paper presents a novel electrode configuration based SPM design for simple multi degree-of-freedom (DOF) orientation manipulation. Four piezoelectric actuating units are adopted as stators to generate 12 orientations through the integration and switch of two vibration modes of each piezoelectric actuator, including lateral mode and longitudinal mode. The dynamic characteristics associated with the design parameters at each vibration mode are experimentally obtained to evaluate the performance of the proposed SPM design.
Wireless Power and SIMO Control Based on Magnetic Coupling Resonance Using in Delta Robot
Authors: Wang Jue , Chen Genliang , Wang Hao
Published: November 2019

Resonance selectivity is a new way to achieve “Single-input Multi-output” (SIMO) system via wireless electromagnetic power transmission. But it is limited to low power and open loop systems. This paper presents a new method that uses the principle of resonance selectivity of which system is close loop and the power is over 10w. By using this method, we drive three DC motors to control a delta robot which is based on flexible linkages with feedback control. In this paper, we achieve the position control of delta robot through SIMO and wireless control. This paper introduces the principle of wireless control based on magnetic coupling resonance and the details about control system, and the fabrication and analysis of delta robot based on flexible linkages. According to the results of our experiment, we demonstrate that this method can be applied to control delta robot.
A Numerical Model to Predict Dynamic Performance of Layered Gears at Starved Lubrication
Authors: Dong Qingbing , Wei Jing , Li Yan , Xu Lixin
Published: November 2019

Gears of modern industry are required to have a good fatigue performance to transmit power and motion through the contact interfaces. Composite layered surfaces can effectively improve the damage resistance of gears and decrease the friction coefficients. However, improper surface modification may induce intensive stress concentrations at the joint interfaces of the strengthening layers and cause unexpected damages to the flanks. Furthermore, the amount of lubricant at the inlet may probably be insufficient to establish fully flooded condition, which may result in starvation and accelerate damages to the gear sets.

In this study, a starved elastohydrodynamic lubrication (EHL) model in three-dimensional (3D) line contact for layered gears is developed. The potential energy method is employed to determine the load distribution along the action line. The loading force is assumed to be balanced by the lubrication pressure, which is derived by discretizing the dimensional Reynolds equation into a solvable matrix with the consideration of the enforced boundary conditions due to the inlet oil supply. The transient evolution of lubrication is investigated to evaluate the load-carrying capability of the lubricant film at various starvation conditions. The influence coefficients related to the displacements and stresses of the layered material system are determined with the assistance of the fast Fourier transform (FFT) algorithm, and the effects of the layer properties and the fabrication methods are evaluated. Such analysis may provide insightful information for the optimization of material systems with fabricated layers and engineering design of gears.
Promoting Energy-Efficient Driving Using Associative Graphical Displays: Can a Cup of Coffee Encourage You to Drive More Smoothly?
Authors: Potvin-Bernal J. , Shu L. H.
Published: November 2019

Substantial energy savings during the use phase of internal-combustion and electric automobiles can be achieved by increasing eco-driving behavior, particularly reduced acceleration and braking. However, motivating widespread adoption of this behavior is challenging, with obstacles including incompatibility with drivers’ values and priorities, and disassociation between drivers’ actions and observable consequences. Efforts focused on informational approaches, e.g., training programs and educational campaigns, are both difficult to scale up and largely ineffective, with drivers reluctant to make long-term changes. Alternatively, behavior can be influenced by redesigning the context within which the behavior occurs. Such an intervention must be effective across demographics and underlying behaviors to achieve ubiquity. The current study investigates the perceived effect on driving style of a simple graphical dashboard display depicting an animated coffee cup. This display incorporates associative mental models and contextual relevance to increase the salience of inefficient vehicle movements and nudge drivers to adopt a smoother driving style. An online Amazon-Mechanical-Turk survey with 92 participants revealed a significant preference for the coffee cup over two other displays when controlling for demographic variables. This result offers preliminary evidence suggesting that greater success at promoting eco-driving may be achieved by using a behavioral nudge.
Designing Lightweight Tensegrity-Based Structures and Materials of Tailorable Thermal Expansion
Authors: Silverman Rochelle E. , Hernandez Edwin A. Peraza
Published: November 2019

In this work, we analyze and design structures and materials that possess custom thermal expansion. These structures and materials are composed of a base unit inspired by the tensegrity “D-bar” (or double-pyramid) topology. We derive, for the first time, analytical equations for the linearized and geometrically exact coefficients of thermal expansion (CTEs) of bi-material D-bar structures with arbitrary shape and complexity. Numerical results obtained using the geometrically exact CTE equations are compared with results obtained using the linearized CTE equations, showing that the latter are accurate only in cases where temperature changes are small. Further results show that D-bar structures of low complexity can produce a wide range of CTEs, including positive, zero, and negative values. These CTE values are exhibited for a range of materials that allows for easy manufacturing (materials with CTE ratios as low as 2). Thus, it is concluded that D-bar structures show promise for applications in aerospace engineering and other fields where new materials of tailorable thermal expansion are needed to decrease the substantial thermal stresses caused by large temperature changes.
On the Use of Multi-Disciplinary Optimisation Methods for Road Vehicle Passive Suspension Design
Authors: Yang Liunan , Ballo Federico , Previati Giorgio , Gobbi Massimiliano , Mastinu Gianpiero
Published: November 2019

Two widely used decomposition-based multi-disciplinary optimisation (MDO) methods, namely analytical target cascading (ATC) and collaborative optimisation (CO), are applied to the design of the suspension system of a road vehicle. Instead of directly optimising the spring stiffness and the damping coefficient, three parameters of the spring and three parameters of the damper are selected as design variables. Discomfort, road holding, and the total mass of the spring-damper system, are considered as objective functions. An investigation is completed to analyse the performance of the two decomposition methods compared with the conventional all-in-one (AiO) formulation in terms of efficiency and applicability.
Design of a Robotic Cannula for Robotic Lumber Discectomy
Authors: Ding Yang , Johnson Benjamin V. , Cappelleri David J.
Published: November 2019

In this paper, the design of the robotic cannula for minimally invasive robotic lumbar discectomy is presented. Lumbar discectomy is the surgery to remove the herniated disc material that is pressing on a nerve root or spinal cord. Recently, a robotic approach to performing this procedure has been proposed that utilizes multiple teleoperated articulated instruments inserted into the surgical workspace using a single cannula. In this paper, we propose a new robotic cannula system to work in conjunction with this new procedure. It allows for the independent teleoperated control of the axial position and rotation of up to three surgical instruments at the same time. The mechanical design, controller design, and prototype of new system are presented in this paper demonstrating a fully functioning device for this application. A novel worm gear and rack system allow for the instrument translation while and embedded gear trains produce the rotational movement. Steady-state errors of less than 50 μm for translation and less than 2° for rotational motion are obtained.
Influence of the Case Properties After Nitriding on the Load Carrying Capacity of Highly Loaded Gears
Authors: Sitzmann André , Tobie Thomas , Stahl Karsten , Schurer Stefan
Published: November 2019

The load carrying capacity of highly loaded gears can be increased by thermochemical surface treatments such as nitriding or case hardening. In contrast to case hardening, the nitriding treatment is carried out at lower process temperatures and therefore creates lower distortion. As a result, grinding after nitriding is usually not necessary. Nitrided gears are ordinarily characterized by a thin, high-hardness, a few micrometers thick compound layer of iron and alloy element nitrides directly on the surface and a subsequent diffusion layer reaching more deeply into the material. Nitriding, therefore, provides an alternative to case hardening for distortion-sensitive components and offers potential for cost savings in the production of highly loaded gears.

This publication will focus on the influence of nitriding on the load carrying capacity of highly loaded gears. In addition, this paper summarizes the current state of knowledge of nitrided gears and gives an insight into current research in the field of nitrided gears. In particular, the influence of the compound layer on the tooth root bending strength and the flank load carrying capacity achieved within the research project FVA 386 II is discussed.
Affine ICP for Fine Localization of Smart-AGVs in Smart Factories
Authors: Yılmaz Abdurrahman , Temeltaş Hakan
Published: November 2019

With the emergence of the concept of Industry 4.0, smart factories have started to be planned in which the production paradigm will change. Automated Guided Vehicles, abbreviated as AGV, that will perform load carrying and similar tasks in smart factories, Smart-AGVs, will try to reach their destinations on their own route instead of predetermined routes like in today’s factories. Moreover, since they will not reach their targets in a single way, they have to dock a target with their fine localization algorithms. In this paper, an affine Iterative Closest Point, abbreviated as ICP, based fine localization method is proposed, and applied on Smart-AGV docking problem in smart factories. ICP is a point set registration method but it is also used for localization applications due to its high precision. Affine ICP is an ICP variant which finds affine transformation between two point sets. In general, the objective function of ICP is constructed based on least square metric. In this study, we use affine ICP with correntropy metric. Correntropy is a similarity measure between two random variables, and affine ICP with correntropy tries to maximize the similarity between two point sets. Affine ICP has never been utilized in fine localization problem. We make an update on affine ICP by means of polar decomposition to reach transformation between two point sets in terms of rotation matrix and translation vector. The performance of the algorithm proposed is validated in simulation and the efficiency of it is demonstrated on MATLAB by comparing with the docking performance of the traditional ICP.
A Comparative Study of Metal Additive Manufacturing Processes for Elevated Sustainability
Authors: Min Wenbo , Yang Sheng , Zhang Ying , Zhao Yaoyao Fiona
Published: November 2019

Metal additive manufacturing (AM) processes have gone through a compound growth over the past decade, and the technology is widely applied in industries like aerospace, automobile and bio-medical fields. There is an increasing need to understand and improve its sustainability given the high profile of existing environmental challenges. This paper aims at developing a precise comparative model for the three major metal AM processes (including Laser Powder Bed Fusion (LPBF), Electron Beam Melting (EBM), and Direct Energy Deposition (DED)) with respect to environmental performance assessment with a future goal of providing closed-loop feedbacks for design optimization with elevated sustainability. To improve the precision of previously reported models, new factors including embodied impacts of machine and recycled powder, operation patterns, system lifespan and batch size, are considered. A topologically optimized rocket bracket made of Ti6Al4V is used as an example to investigate the environmental performance of the three processes. The results showed that given the same design solution, the EBM had the lowest environmental impacts for low batch size, while the DED excelled at production efficiency.
Requirement Generation: Lecture Intervention Impact on Variety and Novelty
Authors: Elena Maria Vittoria , Summers Joshua D.
Published: November 2019

The study presented here explores the influence that an educational intervention has on students in generating requirements during a design task. An experiment was performed in a fourth-year level mechanical engineering design course in which student participants are given a design problem for which they generated a list of requirements, a lecture on requirements in engineering design, and a second design problem for which they generated a second list of requirements. The results from the two problems were tested for determine whether the problems were similar in terms of variety and novelty of requirements generated. The effects of the lecture were evaluated by comparing results from the pre- and post-lecture activity with the two problems. Variety was assessed by sorting the individual requirements generated by each participant into eighteen categories. Novelty was evaluated on the level of uniqueness of the requirement against the complete set generated by all participants, based on both syntax and semantic filtering. The findings suggest that the lecture had a positive impact on the students in increasing the variety of the requirements generated individually by the participants. Further, all the identified novel requirements belonged to the activity performed after lecture.
Second Order Reliability Method for Time-Dependent Reliability Analysis Using Sequential Efficient Global Optimization
Authors: Hu Zhangli , Du Xiaoping
Published: November 2019

Reliability depends on time if the associated limit-state function includes time. A time-dependent reliability problem can be converted into a time-independent reliability problem by using the extreme value of the limit-state function. Then the first order reliability method can be used but it may produce a large error since the extreme limit-state function is usually highly nonlinear. This study proposes a new reliability method so that the second order reliability method can be applied to time-dependent reliability analysis for higher accuracy while maintaining high efficiency. The method employs sequential efficient global optimization to transform the time-dependent reliability analysis into the time-independent problem. The Hessian approximation and envelope theorem are used to obtain the second order information of the extreme limit-state function. Then the second order saddlepoint approximation is use to evaluate the reliability. The accuracy and efficiency of the proposed method are verified through numerical examples.
Modeling Known Design Concepts and Managing Their Functional Coupling Modules to Balance Upstream Objectives and Downstream Constraints for New Product Development
Authors: Wang Chu-Yi , Lu Stephen C.-Y.
Published: November 2019

Product development involves many trade-offs between upstream objectives (e.g., customer needs) and downstream constraints (e.g., modularity, manufacturability, etc.) Conceptual design, when design concepts are generated and improved, is the most important product development stage when these tradeoffs are made. However, when designers try to improve a known design concept of a current product during product development, it is often difficult for them to be both creative (i.e., meeting new objectives) and practical (i.e., incorporating existing constraints) at the same time. This paper presents a method that models known design concepts and manages their functional couplings for designers to achieve these difficult balances systematically during concept improvement. The modeling involves three steps. The first is to represent the known design concept as a dual-hierarchy by decomposing it into sub-concepts and identifying their functional requirements. The second is to find “functional schematics,” defined as a design matrix with minimal complexity, to manage functional couplings of the sub-concepts. The third is to build the executable modules based on the functional schematics. The model help designers achieve the most desirable level of upstream-downstream balance. A coffeemaker example is included to show how such a model of design concept is created and its design coupling modules are managed. The result also suggests that this approach can be used to create a “product family” from the base (or an existing) product to meet continually changing market demands.
Actuated Dual-Slip Model of Planar Slope Walking
Authors: Galindo Raul Lema , Weimholt Elise , Schmiedeler James P.
Published: November 2019

The planar dual spring-loaded inverted pendulum (dual-SLIP) model is a well-established passive template of human walking on flat ground. This paper applies an actuated extension of the model to walking on inclines and declines to evaluate how well it captures the behavior observed in human slope walking. The motivation is to apply the template to improve control of humanoid robot walking and/or intent detection in exoskeleton-assisted walking. Gaits of the actuated planar dual-SLIP model are found via the solution of a constrained nonlinear optimization problem in ten parameters. The majority of those parameters define the actuation scheme that injects energy for incline walking and absorbs energy for decline walking to achieve periodic, nonconservative gaits. Solution gaits across the speed range of 1.0 to 1.6 ms and slope range of −10 to 10 degrees exhibit some of the characteristics of human walking, such as the effect of slope on stance duration, step frequency, and step length. Efforts to reduce the number of parameters optimized by enforcing relationships observed in the solution gaits proved unsuccessful, suggesting that future work must trade off model complexity with fidelity of representation of human behavior.
Machine Learning Assisted Prediction of the Manufacturability of Laser-Based Powder Bed Fusion Process
Authors: Zhang Ying , Dong Guoying , Yang Sheng , Zhao Yaoyao Fiona
Published: November 2019

Laser-based powder bed fusion (LPBF) process is a type of additive manufacturing process which is able to produce complex metal geometries. The fast development of laser-based powder bed fusion process offers new opportunities to the industries. Comparing to the conventional manufacturing process, LPBF offers more freedom on the shape complexity and hierarchical complexity. Even though the LPBF process has many advantages, there are still many constraints on LPBF. At the current stage, LPBF process still has a very high threshold for industrial application. It requires designers to have extensive knowledge of LPBF process to make the design manufacturable. The need for the automatic manufacturability analysis in the early design stage is essential. In this paper, a novel approach on analyzing the manufacturability of LPBF process is introduced. The machine learning model is developed to predict the manufacturability of LPBF. The unique dataset is established as the training examples. The proposed method achieves very competitive accuracy on analyzing the manufacturability of LBPF. The limitation and future work will be discussed in the end.
Health State Assessment and Lifetime Prediction Based on Unsupervised State Estimation
Authors: Jihin Rosmawati , Söffker Dirk
Published: November 2019

Assessment of system health and prediction of remaining useful life can be performed effectively through the evaluation of degradation levels configured by multiple states. Commonly, degradation progression is modeled according to the specific configuration using existing algorithms with assuming numbers and state conditions. However, due to the complexity, especially in the case of a system with multiple hidden states, the proper configuration is hard to assign and to identify. The need for unsupervised state estimation process to assist degradation modeling preventing under or over assumption becomes obvious. Among the existing approaches is the application of clustering methods to classify data and to estimate the number of degradation states might exist. However, integration into the lifetime prediction framework is still infancy and often not considered. Therefore, in this work, a previously developed state machine lifetime model is extended to allow flexibility in configuring state topology based on K-means clustering algorithm and cluster validity index for the optimal number of states identification. Combining unsupervised state estimation process with a new state machine lifetime model has transformed it into a semi-supervised prognostic approach. For validation, hydraulic pressure data from tribology experiment are deployed for training and test the algorithm. Based on the evaluation, this approach demonstrates the ability to improve health state assessment and lifetime prediction in a more flexible way to address the variability in the system.
Programmable Logic Gates Based on Tunable Multistable Mechanisms
Authors: Zanaty Mohamed , Schneegans Hubert , Vardi Ilan , Henein Simon
Published: November 2019

Binary logic operations are the building blocks of computing machines. In this paper, we present a new programmable binary logic gate based on programmable multistable mechanisms (PMM), which are multistable structures whose stability behavior depends on modifiable boundary conditions as defined and analyzed in our previous work. The logical state of a PMM is defined by its stability and logical operations are implemented by modifying the stability behavior of the mechanism.

Our programmable logic device has two qualitatively different sets of inputs. The first set determines the logic function to be computed. The second set represents the logical inputs. The output is a single logical value, “true” if the mechanism changes state and “false” otherwise. In this way, we are able to mechanically implement a set of binary logical operations.

This implementation is validated using an analytical model characterizing the qualitative stability behavior of the mechanism. This was further verified using finite element analysis and experimental demonstration.
Low-Cost Real-Time Vision Platform for Spatial Temperature Control Research Education Developments
Authors: Viola Jairo , Radici Alberto , Dehghan Sina , Chen YangQuan
Published: November 2019

Temperature control is present in many industrial processes, making this skill mandatory for the control engineers. For this reason, different training temperature platforms have been created for this purpose. However, many of these platforms are expensive, require elaborate facility accommodations, and have higher heating and cooling times, making not suitable for teaching and training. This paper presents a low-cost educational platform for temperature control training. The platform employs a Peltier module as a heating element, which has lower heating and cooling time than other thermal system implementations. A low-cost real-time thermal camera is employed as a temperature feedback sensor instead of a standard thermal sensor. The control algorithm is developed in Matlab-Simulink and employs an Arduino board as hardware in the loop to manage the Peltier module. A temperature control experiment is performed to show that the platform is suitable for teaching and training experiences not only in the classroom but for engineers in the industry.
Embedding Cybersecurity Into Design Education: Increasing Designers’ Awareness of Cybersecurity Throughout the Design Process
Authors: Kim Euiyoung , Kwon Jieun , Yoon JungKyoon , Agogino Alice M.
Published: November 2019

As more digital devices with sensing capabilities are introduced into users’ daily lives, the risks of threats to data and privacy and security have increased. While cybersecurity has been acknowledged as an important concern in developing products with digital services, currently available design methodologies and practices offer limited effective guidance to designers to explicitly address cybersecurity issues. In this paper, we present a case study from a product design course at the University of California, Berkeley, where the course’s teaching team implemented an intervention in the form of cybersecurity-focused educational materials into the design process. The baseline and post-intervention survey results indicate that the cybersecurity intervention throughout the course had positively influenced the students’ awareness of cybersecurity (p < 0.001, SD = 0.79, 26% increase in score, Cohen’s d = 0.81). The intervention provoked the designers to consider and include aspects of cybersecurity in developing their design solutions throughout most of the design process. However, their increased awareness aside, the extent of the student teams considering cybersecurity had tapered off over the 6-week design course with little noticeable influence in the final design.
Computational Design of 4D Printed Shape Morphing Multi-State Lattice Structures
Authors: Lumpe Thomas , Shea Kristina
Published: November 2019

4D printed structures can change their properties and functionalities as a response to a change in the environmental conditions, such as a change in the temperature. A heat stimulus can be used to trigger a transition between two states of a shape memory polymer. Specially designed structures made from these materials can transform into different shapes at different temperatures and can be useful for applications in morphing wings or car panels. Most of these structures, however, are still designed by hand and possess limited load carrying capabilities in at least one of their states. Here, it is shown how complex lightweight structures with multiple stable states can be designed using material modeling and structural optimization methods. By distributing different materials to different parts of the structure, local stiffness gradients are introduced, giving rise to architected global deformations under a single, locally applied load. The shape deformations can be either continuous over the whole structure or discrete only in small regions. The results demonstrate how active materials can be used in a new way to design shape morphing, lightweight lattice structures with different stable states and without sacrificing their structural capabilities.
A Multisensory Virtual Reality System for Astronauts’ Entertainment and Relaxation
Authors: Carulli Marina , Bordegoni Monica , Bernecich Francesca , Spadoni Elena , Bolzan Patrizia
Published: November 2019

A research area of interest is that one concerning the design of solutions for improving the life conditions of users in extreme environmental situations. An example is the spacecraft environment, where astronauts are subject to particular conditions, due to the extreme environment. The isolated and confined environment influences behaviors and perceptions. This situation can impact both on astronauts’ moods, cause states of depression, and impact on their performance in working activities. A spacecraft can be the Space Station orbiting the Earth, or future means of transportation used for travelling to other planets. In both cases the space should be designed so as to offer the best possible living and working conditions to the astronauts.

The research presented in this paper aims at designing and developing a multisensory VR system for the entertainment and the relaxation of astronauts. The use of VR technology allows us to overcome physical and psychological boundaries of the confined space, which is typical in a spacecraft environment. The sense of smell, which is more linked to visceral emotions than the other senses and can affect various aspects of humans’ physiological and psychological conditions, is used to improve astronauts’ productivity and concentration, and also to relieve their stress and anxiety.
Understanding the Design Neurocognition of Mechanical Engineers When Designing and Problem-Solving
Authors: Vieira Sonia , Gero John , Delmoral Jessica , Gattol Valentin , Fernandes Carlos , Parente Marco , Fernandes António
Published: November 2019

This paper presents results from an experiment to determine brain activation differences between problem-solving and designing of mechanical engineers. The study is part of a research project whose goal is to correlate design cognition with brain behavior across design domains. The study adopted and extended the tasks described in a fMRI study of design cognition and measured brain activation using EEG. By taking the advantage of EEG’s temporal resolution we focus on time-related neural responses during problem-solving compared to design tasks. Statistical analyses indicate increased activation when designing compared to problem-solving. Results of time-related neural responses connected to Brodmann areas cognitive functions, contribute to a better understanding of mechanical engineers’ cognition in open design tasks.
Mode Localization in Two Coupled Nearly Identical MEMS Cantilevers for Mass Sensing
Authors: Rabenimanana Toky , Walter Vincent , Kacem Najib , Le Moal Patrice , Bourbon Gilles , Lardiès Joseph
Published: November 2019

This paper investigates the mass sensing in a mode-localized sensor composed of two weakly coupled MEMS cantilevers with lengths 98μm and 100μm. The two resonators are connected by a coupling beam near the fixed end, and the shortest cantilever is electrostatically actuated with a combined AC-DC voltage. The DC actuation voltage is tuned to compensate the length difference and geometrical imperfections in order to dynamically equilibrate the system. An analytical model of the device using the Euler Bernoulli beam theory is presented and the required DC voltage to reach the balanced state is used. A mass perturbation is then added on the long cantilever and the eigenstate shifts and amplitude ratios in each mode are calculated for different couplings. Results show that the amplitude ratio of the second mode is the best output metric for the mass detection. For the validation of the model, an experimental investigation is carried out by using devices fabricated with the Multi-User MEMS Processes. Three different couplings are considered and the long cantilever is designed with a mass attached at its end. Instead of adding a mass on the device, we remove this part with a probe to introduce the perturbation. When the mass is removed, the experimental frequency responses of the device show localized vibrations, which are in good agreement with the theoretical results.
Acoustic Non-Reciprocal Band Structure in a Passive, Nonlinear, 1D Material
Authors: Fang Lezheng , Darabi Amir , Vakakis Alexander F. , Leamy Michael J.
Published: November 2019

Acoustic non-reciprocity, referring to the phenomenon of path-dependent propagation, has diverse applications in mechanical devices. This paper presents a numerical study on a periodic triangle-shape structure that breaks reciprocity in a passive manner over a broad range of frequency and energy. The proposed structure contains strong nonlinearity and geometric asymmetry, which contributes to a direction-dependent dispersion relationship. When the signal frequency falls in the band pass in one direction, and band gap in the other, a unidirectional wave propagation results. The system achieves giant non-reciprocity with minimal distortion in the frequency content of the signal.
A Parametric Modeling Approach for Prediction of Load Distribution due to Fluid Structure Interaction on Aircraft Structures
Authors: Barutcu Ahmet , Gorguluarslan Recep M.
Published: November 2019

The Fluid Structure Interaction (FSI) is a critical multi-physics phenomenon in the aerospace applications for computing loads. Including the FSI effects on the analysis requires high computational cost. A computationally efficient framework is presented in this study for predicting the FSI effects. The high-fidelity structural model is reduced on the elastic axis by using an efficient structural idealization technique. A parametric model generation process is developed by using Bezier surface control vertices (CVs) to estimate the changing load distribution under deformation. The aircraft wing outer surface is created by using Bezier surface modeling method for this purpose. The CVs of the surfaces are perturbed to predict the effect of the deformed shape on the load distribution. This method allows to predict the load distribution by using a few CVs instead of using all grid points. The Aerodynamic Influence Coefficients (AIC) matrix is generated based on the predicted loads based on this parametric modeling approach instead of conducting computationally expensive fluid flow analysis. The presented framework is implemented for an aircraft wing design to show its efficacy.
An Analytical Investigation of the Impact of Design Parameters on the Performance of Centrifugal Pendulum Vibration Absorbers
Authors: Sarikaya Bahadir , Inalpolat Murat , Lee Hyun Ku , Kim Moo Suk
Published: November 2019

A generalized nonlinear time-varying, planar dynamic model of bifilar centrifugal pendulum vibration absorbers (CPVA) is proposed. This dynamic model enables fast prediction of vibration reduction performance of any CPVA design considering the impact of absorber rollers, gravity, end stops and translational motion of the system. The modeling framework provides comparative, simultaneous simulation results for numerous different design possibilities, and thus can be used to optimize CPVA designs. The dynamic model is generic and can handle N individually designed absorbers on a rotor with numerous path options ranging from circular to cycloid. Absorbers can be designed to be equally or unequally spaced. In this study, first the dynamic model of the bifilar CPVAs is derived. Then, case studies are provided to showcase the capabilities of the modeling framework. Initially, maximum applicable dynamic torque to a CPVA and vibration reduction performance are investigated by considering the effect of tuning order and different absorber path options for different operating speeds. Then, impact of different modelling features on system frequency response and limit dynamic torque is investigated. Interactions between the important design parameters are highlighted. Finally, the influence of end stop positioning on the CPVA dynamic response is illustrated.
Construction of Multi-Domain System Simulation Model for Trade Studies in System Design Considering Multiple Scenes
Authors: Oizumi Kazuya , Ishida Keita , Uchibori Yoshihiro , Aoyama Kazuhiro
Published: November 2019

As a product is sold globally, usages of the product have much wider variety. Thus, a product needs to be designed considering multiple scenes. To certify that the product performs properly in any scene, industries started to apply Model Based Systems Engineering (MBSE). Whereas multi-domain system simulations are regarded as a prominent approach for the system design of a product, construction of model depends on knowledge and sense modelers. This paper proposes a modelling method to construct appropriate multi-domain system simulation models while reducing dependencies to senses of modelers. The proposed method comprises two parts. First, significant tradeoffs to be studied by the simulation are specified. Second, features of simulation models are deliberated for specified tradeoffs. To specify significant tradeoffs, product and scenes where the product is used are integrated into a model. Further, to deliberate features of simulation model, cognitive model of physical phenomena in a product is employed as well. The proposed method was applied to the development of continuously variable transmission to verify its validity.
Kirigami-Based Deployable Transcrease Hard Stop Models Usable in Origami Patterns
Authors: Andrews David W. , Avila Alex , Butler Jared , Magleby Spencer P. , Howell Larry L.
Published: November 2019

Stopping origami in arbitrary fold states can present a challenge for origami-based design. In this paper two categories of kirigami-based models are presented for stopping the fold motion of individual creases using deployable hard stops. These models are transcrease (across a crease) and deploy from a flat sheet. The first category is planar and has behavior similar to a four-bar linkage. The second category is spherical and behaves like a degree-4 origami vertex. These models are based on the zero-thickness assumption of paper and can be applied to origami patterns made from thin materials, limiting the motion of the base origami pattern through self-interference within the original facets. Model parameters are based on a desired fold or dihedral angle, as well as facet dimensions. Examples show model benefits and limitations.
Predicting Finite Element Submodel Boundary Conditions for Contact Models Using Richardson Extrapolation
Authors: Sracic Michael W. , Elke William J.
Published: November 2019

This paper considers an efficient way to apply submodeling methods to finite element models using Richardson Extrapolation. A problem is considered where a rigid cylindrical indenter contacts an elastic half plane (RCEHP). A submodeling method is introduced where the errors of the displacements on the boundaries of the submodel are controlled by employing a best-fit Richardson Extrapolation curve. Specifically, the curve is fit to the convergence relationship of various estimates of submodel boundary displacements. The method is tested on the RCEHP problem, and the results of the model predictions for maximum contact pressure are compared to an analytical and converged global model result.

The submodeling method predicted the maximum contact pressure of the RCEHP contact interface to be about 7% higher than the analytical prediction and 5% higher than the converged global model prediction. The error is likely due to the selection of the global and submodel domains, the numerical algorithm used to estimate the Richardson Extrapolation Curve Fits, and the mesh refinements used for the various models. The proposed method solved in about 42.6 minutes while the converged global model solved in 11.19 hours. Future work will aim to provide best practices to reduce error and maximize computational time savings when using the method.
Reverse Engineering and Optimization of a Steering Mechanism Component in a Competition Ground Vehicle
Authors: López-Pachón Matheo , Gonzalez-Cárdenas Diego , Gonzalez-Mancera Andres
Published: November 2019

In this paper, reverse engineering of a steering system component in a competition vehicle was successfully carried out. A CAD model was generated by means of NURBS curves from 3D scanning. Additionally, two manufacturing methods were compared to obtain the component namely, CNC and Casting. Simultaneously, a topological optimization was carried out from the failure diagnosis of the part; hence, to determine the failure, different loads were simulated in a transient and elastoplastic FEM simulation using an isotropic bilinear hardening model, in order to detect the displacement of a faulty component. The methodology implemented in the study showed satisfactory results for the different stages of the process.
A Lower Pad Adjustable Bearing Reducing Vibration Response of Rotor Systems During Acceleration
Authors: Zhang Lei , Xu Hua , Zhang Shenglun , Pei Shiyuan
Published: November 2019

A lower pad movable bearing is proposed which has the ability to change the lubricating performance of the journal bearing. The structure and working principle of the adjustable bearing are introduced. This bearing can adjust the working status of the rotor system by changing the position of the bearing pad and reduces the vibration amplitude of rotor. In this paper, a simple rotor bearing finite element model is used to study the vibration response of the rotor system. Through research, it is found that larger ellipticity can effectively reduce the amplitude of the rotor when the rotor speed is running at a certain speed away from the critical speed, and the vibration suppression effect can reach 67%. When the rotor passes the critical speed, reducing the ellipticity can significantly reduce the resonance amplitude of the rotor, and the vibration suppression effect reaches about 37%. In addition, when the rotational speed increases to twice the critical speed, the oil film oscillation occurs under light load condition, which can be suppressed by reducing the ellipticity. Adjustable bearing can then be proposed to adaptively improve the vibration of the rotor system based on the rotor speeds.