bluuebunny/crossref_metadata_2025 huggingface dataset:
Design Sprint for Complex System Architecture Analysis
Authors: Hölttä-Otto Katja , Niutanen Valtteri , Eppinger Steven , Browning Tyson R. , Stowe H. Mike , Lampinen Riku , Rahardjo Andhikaputra
Published: November 2018

A rigorous, in-depth analysis is a common approach in complex system design. Elsewhere, however, more iterative and agile processes and open innovation have become commonplace. We experiment with an agile hackathon-type design sprint for solving industry-provided, complex system engineering problems. In a typical complex system project, significant domain expertise is expected and only one in-depth analysis is typically conducted to make recommendations for a given problem. The question we explore is whether a quick sprint with non-domain experts can result in useful insights for further analysis. We tasked seven teams in parallel to conduct analysis and suggest recommendations for a given company case in only a few hours. The industry challenge was to propose system changes that would mitigate risks due to the long lifecycle of the system and long time from order to delivery. The teams were given two a priori decomposed design structure matrices, representing the product architecture at two levels of granularity, as well as access to several analysis tools. The design sprint resulted in seven sets of recommendations, each with unique insights. The results and their variety highlighted the type of recommendations any given analysis direction would give if pursued further. It provided insights about the many different ways to potentially address the given challenge. As expected, it also highlighted the difficulty of analysis due to lack of detailed system knowledge. Nevertheless, the sprint was considered successful and meaningful as well as an effective means to augment traditional complex system analysis.
Active Vibration Control Design of Multi-Rigid-Flexible-Body Systems Based on Transfer Matrix Method for Multibody Systems
Authors: Chen Gangli , Rui Xiaoting , Ding Yuanyuan , Lu Hanjing
Published: November 2018

A new approach for active vibration control design of multi-rigid-flexible-body systems based on transfer matrix method for multibody systems (MSTMM) is presented in this paper. The vibration characteristics are computed by solving homogeneous linear algebraic equations. Then, the augmented eigenvector and body dynamics equation are adopted to derive the state space representation by combining modal superposition method. Furthermore, Linear Quadratic Gaussian (LQG) control strategy is employed to design the control law. Compared with the conventional methods, the proposed method has the following features: without system global dynamics equation, high programming, low order of system matrix and high computational speed. Formulations as well as a numerical example are given to validate the proposed method.
Developments in Transfer Matrix Method for Multibody Systems (Rui Method) and its Applications
Authors: Rui Xiaoting , Wang Xun , Zhou Qinbo , Zhang Jianshu
Published: November 2018

Compared to classical mechanics, the transfer matrix method for multibody systems is a rather novel approach for analyzing multibody system dynamics. For its features that it avoids the global dynamics equation of the system, keeps a high computational speed and allows highly formalized programming, this method has been widely used in science research as well as design of dynamics performance and experiments for various complicated mechanical systems. Up to now, there have been more than 50 research directions in science research and key engineering applications based on this method. In this paper, the following aspects are systematically reviewed: history, basic principles, formulas, algorithm, automatic deduction theorem of overall transfer equation, visualized simulation and design software, comparison with other dynamics methods, tendency, and future research directions.
Study on Response of Launch Vehicle Under Ground Wind Loads Based on Transfer Matrix Method for Multibody Systems
Authors: Wang Xun , Rui Xiaoting , Yang Fufeng
Published: November 2018

In order to study dynamics response of a launch vehicle under ground wind loads, the dynamics model of a launch vehicle erected on the pad is developed based on transfer matrix method for multibody systems and the theory of structural wind engineering. The overall transfer equation, overall transfer matrix, and characteristics equation of the system are deduced based on the automatic deduction theorem of overall transfer equation of multibody system. The equation governing the motion of the launch vehicle is obtained by using the orthogonality of augmented eigenvector. The vibration characteristics, and frequency domain and time domain dynamics response under ground wind loads of the launch vehicle are simulated. The simulation results show that the eigenfrequencies obtained by the proposed method and ordinary dynamics method have good agreements. The paper provides an effective approach to compute the dynamics response of the launch vehicle under ground wind loads.
Hydro-Pneumatic Suspension for a 6x6 All-Terrain Amphibious Vehicle: Design and Testing
Authors: Gobbi Massimiliano , Marinaro Giuseppe , Mastinu Gianpiero , Previati Giorgio
Published: November 2018

Special purposes off-road vehicles are mainly used in very harsh conditions and environments. In this paper, the design and testing of the suspension system of a off-road amphibious vehicle is described. The suspension system of such vehicles has to comply with different, and conflicting, performances. It has to guarantee suitable on- and off-road characteristics, while, at the same time minimize the disturbance of the wheels during navigation. Starting from the experimentally defined mission profile of the vehicle, the design and testing process of the hydro-pneumatic suspension is presented. Mathematical models of the thermal and mechanical behaviour of the hydraulic system are used to optimize its parameters in order to obtain the desired suspension performance. Fatigue tests have been completed to evaluate the evolution of the performance of the system during the entire vehicle life.
Designing Market Thickness and Optimal Frequency of Multi-Period Stable Matching in Cloud-Based Design and Manufacturing
Authors: Thekinen J. D. , Han Yupeng , Panchal Jitesh H.
Published: November 2018

A central issue in two-sided matching markets such as Cloud-Based Design and Manufacturing (CBDM) where agents interact over a long period of time is the design of optimal matching period during recursive implementation. Existing literature provides mechanisms that satisfy useful properties such as stability in a single matching cycle, but they lack studies on the effect of the period of matching cycle on the optimality. To address this gap, we perform simulation studies on a synthetic CBDM scenario where service seekers arrive as a Poisson process with a fixed number of service providers offering resources. We identify the optimal matching period and assess its robustness using sensitivity studies. Optimality is measured in terms of utility obtained by the agents, the number of matches and fairness of the utility distribution. We show that a matching period equal to the ratio of the number of service providers to the arrival rate of service seekers is optimal.
Power Flow Analysis for Hybrid Mass Damper Design
Authors: Chesne S. , Billon K. , Collette C. , Zhao G.
Published: November 2018

Tuned Mass Damper (TMD) are largely used in many domains like aerospace or civil engineering. While very simple and robust, their damping capability is proportional to their mass, which represents an important shortcoming. Hybrid-TMDs propose to combine active systems to an optimal passive device. Nevertheless, stability problems can result from this association. In this study, the passivity concept is used to design a control law enforcing the hybrid-TMD to be hyperstable. Consequently, the resulting Hybrid TMD is fail-safe and unconditionally stable. An analysis of the active and reactive powers also illustrates the energy flux in the device and its passive nature. Simulations based on an experimental model show the performance of such system.
Thermal Prestress in Composite Compliant Shell Mechanisms
Authors: Stacey Jonathan P. , O’Donnell Matthew P. , Schenk Mark
Published: November 2018

Due to the anisotropic nature of fibre-reinforced laminates, thermally-induced internal stresses can remain in the material after manufacture. Mismatches between coefficients of thermal expansion are especially prominent in thin shells with fewer plies or large angle variations. Such stresses cause out-of-plane warping and are therefore often deliberately avoided. Utilising their effects on structural behaviour however, can enable stiffness-tailored composite compliant mechanisms. Work detailed in this paper aims to exploit thermal prestress to reduce the torsional stiffness of cross-ply tape laminate springs.

An extension of an analytical tape spring model with composite thermal analysis is presented, which shows that thermal effects cause significant changes to the energy landscapes of thin composite shells. Tape springs that would otherwise be monostable structures become bistable and exhibit greater ranges of low-energy twisting when thermally-induced prestress is present. Predicted shell geometries are compared with finite element models and manufactured samples, showing good agreement between all approaches. The limited feasibility of zero torsional stiffness composite tape springs is discussed, as well as wider challenges involved in manufacturing prestressed composite compliant mechanisms such as fibre misalignment and moisture ingress.
Pulling at the Digital Thread: Exploring the Tolerance Stack Up in Scan to Print Processes
Authors: Mahan Tobias , Doyle Brenna , Meisel Nicholas , Menold Jessica
Published: November 2018

The rise of affordable rapid non-contact digitizers and rapid prototyping tools, such as 3D printers, is enabling the seamless integration of geometric reverse engineering into the early phases of engineering design. Scanning technology has been widely adopted in bio-reverse engineering and the use of high fidelity non-contact scanners, such as Computed Tomography devices, allows designers, doctors, and researchers to digitally model boney structures, design orthotic and prosthetic devices, and preemptively plan complex surgeries. While the combination of 3D scanning and printing processes holds much promise for the fields of reverse engineering, biodesign, and new product development, problems with repeatability, accuracy, and precision have limited the wider spread adoption of 3D scan to print processes. While some studies have explored the errors inherent in higher fidelity scan to print (S2P) processes, no studies have explored the errors in S2P processes that leverage affordable rapid non-contact digitizers. The purpose of this study was to explore at which phases of the S2P process errors are introduced into the digital model. A controlled study was conducted using data from 27 scans using a common off-the-shelf non-contact optical digitizer and a relatively simple workpiece. Data from the digital thread was collected between each phase of the S2P process and compared against a truth model; the geometric and dimensional integrity of the data was calculated through a comparison between the digital model and the original truth model. Results indicate significant differences between digital models at the various steps of the S2P process.
Redesign of the Femoral Stem for a Total Hip Arthroplasty for Additive Manufacturing
Authors: Hanks Bradley , Dinda Shantanab , Joshi Sanjay
Published: November 2018

Total hip arthroplasty (THA) is an increasingly common procedure that replaces all or part of the hip joint. The average age of patients is decreasing, which in turn increases the need for more durable implants. Revisions in hip implants are frequently caused by three primary issues: femoral loading, poor fixation, and stress shielding. First, as the age of hip implant patients decreases, the hip implants are seeing increased loading, beyond what they were traditionally designed for. Second, traditional implants may have roughened surfaces but are not fully porous which would allow bone to grow in and through the implant. Third, traditional implants are too stiff, causing more load to be carried by the implant and shielding the bone from stress. Ultimately this stress shielding leads to bone resorption and implant loosening.

Additive manufacturing (AM) presents a unique opportunity for enhanced performance by allowing for personalized medicine and increased functionality through geometrically complex parts. Much research has been devoted to how AM can be used to improve surgical implants through lattice structures. To date, the authors have found no studies that have performed a complete 3D lattice structure optimization in patient specific anatomy. This paper discusses the general design of an AM hip implant that is personalized for patient specific anatomy and proposes a workflow for optimizing a lattice structure within the implant.

Using this design workflow, several lattice structured AM hip implants of various unit cell types are optimized. A solid hip implant is compared against the optimized hip implants. It appears the AM hip implant with a tetra lattice outperforms the other implant by reducing stiffness and allowing for greater bone ingrowth. Ultimately it was found that AM software still has many limitations associated with attempting complex optimizations with multiple materials in patient specific anatomy. Though software limitations prevented a full 3D optimization in patient specific anatomy, the challenges associated such an approach and limitations of the current software are discussed.
Robust MDSDO for Co-Design of Stochastic Dynamic Systems
Authors: Azad Saeed , Alexander-Ramos Michael J.
Published: November 2018

Optimization of dynamic engineering systems generally requires problem formulations that account for the coupling between embodiment design and control system design simultaneously. Such formulations are commonly known as combined optimal design and control (co-design) problems, and their application to deterministic systems is well-established in the literature through a variety of methods. However, an issue that has not been addressed in the co-design literature is the impact of the inherent uncertainties within a dynamic system on its integrated design solution. Accounting for these uncertainties transforms the standard, deterministic co-design problem into a stochastic one, thus requiring appropriate stochastic optimization approaches for its solution. This paper serves as the starting point for research on stochastic co-design problems by proposing and solving a novel problem formulation based on robust design optimization (RDO) principles. Specifically, a co-design method known as multidisciplinary dynamic system design optimization (MDSDO) is used as the basis for a RDO problem formulation and implementation. The robust objective and inequality constraints are computed per usual as functions of their first-order-approximated means and variances, whereas analysis-based equality constraints are evaluated deterministically at the means of the random decision variables. The proposed stochastic co-design problem formulation is then implemented for two case studies, with the results indicating a significant impact of the robust approach on the integrated design solutions and performance measures.
The Application of Transfer Matrix Method for Multibody Systems in the Dynamics of Sail Mounted Hydroplanes System
Authors: Chen Dongyang , Abbas Laith K. , Wang Guoping , Rui Xiaoting
Published: November 2018

Transfer Matrix Method for Multibody Systems (MSTMM) is easy to formulate, systematic to apply, simple to code and the matrices are low order which contributes to higher computational efficiency than ordinary dynamics methods. The main idea about how to simulate the vibration characteristic and hydroelastic behavior of a submarine sail mounted hydroplanes system based on MSTMM and coupled with Theodorsen flow model is presented in this paper. The simulation results are compared with those theoretical and experimental reported in the existing literature and commercial software simulation, and good results are obtained. The main idea of this paper provides a reference for dynamics of system with fluid-structure interaction (FSI) simulation and analysis of similar problems in the field of engineering.
Rotations in a Non-Orthogonal Frame
Authors: Lu Shengnan , Ding Xilun , Chirikjian Gregory S.
Published: November 2018

This paper is concerned with describing the space of matrices that describe rotations in non-orthogonal coordinates. In scenarios such as in crystallography, conformational analysis of polymers, and in the study of deployable mechanisms and rigid origami, non-orthogonal reference frames are natural. For example, non-orthogonal vectors in the direction of atomic bonds in a molecule, the lattice coordinates of a crystal, or the directions of links in a mechanism are intrinsic. In these cases it is awkward to impose an artificial orthonormal reference frame rather than choosing one that is defined by the geometry of the object being studied. With these applications in mind, we fully characterize the space of all possible non-orthogonal rotations. We find that in the 2D case, this space is a three-dimensional subset of the special linear group, SL(2, R), which is itself a three-dimensional Lie group. In the 3D case we find that the space of nonorthogonal rotations is a seven-dimensional subspace of SL(3, R), which is an eight-dimensional Lie group. In the 2D case we use the Iwasawa decomposition to fully characterize the solution. In the 3D case we parameterize this seven-dimensional space by conjugating elements of the rotation group SO(3) by elements of a discrete family of of four-parameter subgroups of GL(3, R), and using this we derive an inversion formula to extract classical orthogonal rotations from those expressed in non-orthogonal coordinates.
Finite Element Method and Parametric Study on Material Properties and Friction Coefficients for Design of Mechanical Components
Authors: Li Yu Hua , Moon Seung Ki , Chua Zhong Yang , Ngo Teck Hui , Tou Jun Jie , Mohamed Ashrof Bin Mohamed Yusoff
Published: November 2018

In this study, a parametric study on material properties and friction coefficient of mechanical components are investigated through simulating the real working conditions by a numerical method. As the screw rotors are the key components in an air compressor system, the rotors are exposed to complicated loading conditions during operation. The objective of this study is to investigate the effects on the input moment, peak Von Mises stress and the mechanical efficiency of the air compressor system subjected to varying parameters of the material properties of the female rotor and friction coefficients. From the simulation results, the peak Von Mises stress is greatly affected by the parameters of the material property of the female rotor, and the input moment and the mechanical efficiency are slightly influenced in the first condition. And, the peak Von Mises stress is significantly affected by the parameters of the friction coefficients, in the decreasing trend. The input moment is also increased with the increasing parameters of the friction coefficients. The mechanical efficiency is inversely correlated with the input moment, whereby efficiency is greatly reduced with an increase in input moment. The study shows that the proposed numerical method is efficient and suitable to establish the parameters study on the twin screw rotors, and provides an effective approach to investigate the twin screw rotors and improve the design of the system.
Nonlinear Design Model for Multi-Threshold Accelerometer Utilizing Magnetic Induced Multistable Mechanisms
Authors: Zhao Jian , Huang Yu , Liu Pengbo , Fang Qifei , Gao Renjing
Published: November 2018

Different from traditional accelerometer, multi-threshold acceleration switch can be triggered to different working states by external accelerations without complex auxiliary circuits and controlling elements, which has great application potentials in aerospace, vehicle safety and consumer electronics. In this paper, a novel multi-threshold acceleration switch with anti-overloading function is designed and fabricated by incorporating both magnetic multi-stable structures and compliant cantilever contacts, which also can be used to distinguish specific acceleration pulse. To enhance the contact reliability, the magnetic compliant locking mechanism is introduced to prevent bouncing back phenomenon under overload acceleration. Considering the air-damping and multi-magnetic fields coupling effect, the dynamic design model is proposed for analyzing the nonlinear switch response. Then, threshold accelerations can be determined as ac1 = 3.78g, ac2 = 10.2g and ac3 = 6.95g in one direction while threshold accelerations in opposite direction are ac4 = 4.9g, ac5 = 8.47g and ac6 = 5.6g. The switch shows excellent threshold acceleration detection capability, and the inertial switch keeps open while the external acceleration is 0.2g less than the predefined threshold value. The experimental results show that the threshold acceleration with specific pulse width can be accurately identified, and the switch can bear strong overload acceleration comparing to traditional switches. Consequently, the proposed design method provides a new way for intelligent mechanical inertial sensors.
High Degree of Freedom Hand Pose Tracking Using Limited Strain Sensing and Optical Training
Authors: Zhang Wentai , Yu Jonelle Z. , Zhu Fangcheng , Zhu Yifang , Ulu Nurcan Gecer , Arisoy Batuhan , Kara Levent Burak
Published: November 2018

The ability to track human operators’ hand usage when working in production plants and factories is critically important for developing realistic digital factory simulators as well as manufacturing process control. We propose an instrumented glove with only a few strain gauge sensors and a micro-controller that continuously tracks and records the hand configuration during actual use. At the heart of our approach is a trainable system that can predict the fourteen joint angles in the hand using only a small set of strain sensors. First, ten strain gauges are placed at the various joints in the hand to optimize the sensor layout using the English letters in the American Sign Language as a benchmark for assessment. Next, the best sensor configurations for three through ten strain gauges are computed using a support vector machine classifier. Following the layout optimization, our approach learns a mapping between the sensor readouts to the actual joint angles optically captured using a Leap Motion system. Three regression methods including linear, quadratic and neural regression are then used to train the mapping between the strain gauge data and the corresponding joint angles. The final proposed model involves four strain gauges mapped to the fourteen joint angles using a two-layer feed-forward neural network.
Design and Simulation of a Novel Mechanical Power Take-Off for a Two-Body Wave Energy Point Absorber
Authors: Li Xiaofan , Chen Chien-An , Xiong Qiuchi , Parker Robert , Zuo Lei
Published: November 2018

In this paper, a two-body self-react wave energy converter with a novel mechanical Power Take-off (PTO) is introduced. The PTO rectifies the mechanical motion and regulates the flow with a mechanism called Mechanical Motion Rectifier (MMR), which converts the reciprocating motion of the ocean wave into unidirectional rotation of the generator. The overall system is analyzed in both time and frequency domain. In time domain, the piecewise non-linear dynamic model of the MMR PTO is derived, and parameters that could significantly influence the MMR property is extracted. By building the model into WEC-Sim, a time domain wave energy converter (WEC) simulation tool, to simulate and evaluate the performance of the PTO. In addition, the system is modelled as a two-body vibration system for frequency domain analysis in order to further investigate and optimize the proposed wave energy converter. The tunable parameters within the system, including the equivalent mass, the equivalent damping coefficient, and the PTO stiffness, are discussed based on the criteria of maximization of the total output power. To verify the theoretical analysis, a bench test prototype is developed and tested on a hydraulic test machine. The experimental results in line with the derived model and can be used for reasonable estimation on the output power of the proposed system in real ocean conditions.
Development of Experimental Active Magnetic Bearing Device for Measurement of Mechanical Seal Reaction Force Acting on Rotor
Authors: Manabe Hiroki , Yabui Shota , Inoue Hideyuki , Inoue Tsuyoshi
Published: November 2018

In turbomachinery, seals are used to prevent fluid leakage. At seal part, rotordynamic fluid force (RD fluid force), which causes whirling motion of rotor, is generated. Under certain conditions, the RD fluid force may contribute to instability of the machine. There are several cases that the whirling is accompanied by eccentricity due to the influence of gravity, or the whirling orbit becomes elliptical due to the influence of the bearing support anisotropy. In these cases, mathematical modeling of the RD fluid forces becomes increasingly complex. As a result, the RD fluid force measurement is more preferable. To improve the measurement and evaluation technology of the RD fluid force, a method to arbitrarily control whirling of the orbit is required.

In this paper, RD fluid force measurement by controlling the shape of the orbit using an active magnetic bearing (AMB) is proposed. A contact type mechanical seal is used as a test specimen. When the rotating shaft is whirling, the RD fluid force due to hydrodynamics lubrication and the frictional force due to contact occur on the sliding surface. The resultant force of these forces is taken as the reaction force of mechanical seal and the measurement is performed. The measured reaction force of the mechanical seal is compared with simulation results and the validity of the proposed measurement method is confirmed.
Multi-Resolution-Based Contour Corner Extraction Algorithm for Computer Vision-Based Measurement
Authors: Li Jianhua , Liao Lin
Published: November 2018

Corner-based registration of the industry standard contour and the actual product contour is one of the key steps in industrial computer vision-based measurement. However, existing corner extraction algorithms do not achieve satisfactory results in the extraction of the standard contour and the deformed contour of the actual product. This paper proposes a multi-resolution-based contour corner extraction algorithm for computer vision-based measurement. The algorithm first obtains different corners in multiple resolutions, then sums up the weighted corner values, and finally chooses the corner points with the appropriate corner values as the final contour corners. The experimental results show that the proposed algorithm, based on multi-resolution, outperforms the original algorithm in the aspect of the corner matching situation and helps in subsequent product measurements.
Modeling and Testing of a Minimally Powered SOI-DRIE MEMS Pressure Sensor for Discrete Blast Detection
Authors: Fondjo Vicky Taffoti , Fondjo Fotou Franklin , Barham Oliver M. , Khan Muhammad , Rauscher Scott G. , Jean Daniel L.
Published: November 2018

MEMS diaphragms utilizing an embedded cantilever array to sense pressure were investigated in an effort to detect blast-induced loads that potentially cause mild traumatic brain injury (mTBI). Overhanging cantilever beams of varying length sequentially contacted convexly deformed diaphragms during pressure loading to enable binned binary threshold pressure sensing. Diaphragms and overhanging cantilever beam arrays photolithographically defined using double-layer SOI-DRIE processes were designed to minimize footprint and maximize sensing resolution while avoiding diaphragm fracture. Analytic models based on classical plate theory were correlated with a FEA model to guide design decisions by predicting deflection behavior of circular diaphragms under uniformly distributed pressure loads. Fabricated sensors experimentally tested under static conditions revealed good agreement with modeling, and indicated such a sensor may be well-suited for integration into a future wearable device capable of sensing potentially mTBI-causing blasts using minimal power.
Voice of the Customer Oriented New Product Synthesis Over Knowledge Graphs
Authors: Qin Feiwei , Xu Hairui , Zhang Weicheng , Yuan Lin , Li Ming , Liu Yusheng , Liu Ying , Chen Yong
Published: November 2018

The online shopping has been much easier and popular, and meanwhile brings new challenges and opportunities to the field of product design and marketing sale. On one hand, product manufacturers find it challenging to produce new popularly accepted products to meet the customers’ needs; on the other hand, end customers usually feel it difficult to buy ideal goods that they really want, even if navigating a huge amount of commodities. There are indeed a ‘communication gap’ between the customers and manufacturers.

As an effort to partially resolve the issue, this paper proposes a novel product synthesis approach from ‘voice of the customer’ over product knowledge graphs. Here the voice of customers mainly refer to the buyers’ product reviews from online shopping platforms or blogs, while the product knowledge graph is constructed containing professional hierarchical product knowledge on its properties based on ontological models. Using the technologies of natural language processing, we first extract the customs’ polarities on each specific aspect of a product, which are then transited to design requirements on the product’s design components. Based on the requirement extractions, and the pre-built product knowledge, semantic web and reasoning techniques are utilized to synthesize a novel product that meets more customer needs. Typical case studies on mobile phones from raw online data demonstrate the proposed approach’s performance.
Reconfigurable Trusses of Nonlinear Morphing Elements
Authors: Aza Chrysoula , Pirrera Alberto , Schenk Mark
Published: November 2018

Reconfigurable mechanisms are capable of changing their behavior during operation and perform different tasks through changes of their configuration. A compliant, multistable, reconfigurable mechanism is introduced which consists of nonlinear morphing elements assembled in a truss-like configuration. These constituent elements are made of composite strips assembled to form a double-helix and exhibit tailorable nonlinear stiffness characteristics, including bistability. The mechanism’s behavior can be tailored by tuning the inherent properties of the helical components, leading to a wide range of responses. This work explores the reconfigurability of the mechanism, based on the ability to change the helical pitch and the resulting stiffness.
Robust Concept Exploration of Materials, Products and Associated Manufacturing Processes
Authors: Nellippallil Anand Balu , Mohan Pranav , Allen Janet K. , Mistree Farrokh
Published: November 2018

In this paper, we present robust concept exploration using a goal-oriented, inverse decision-based design method to carry out the integrated design of material, product and associated manufacturing processes by managing the uncertainty involved. The uncertainty in complex material and product systems is derived from many sources and we classify robust design based on these sources — uncertainty in noise factors (Type I robust design); uncertainty in design variables or control factors (Type II robust design); uncertainty in function relationship between control/noise and response (Type III robust design); and propagation and potential amplification of uncertainty in a process chain (Type I to III robust designs across process chains). In this paper, we introduce a variation to the existing goal-oriented inverse decision-based design method to bring in robustness for multiple conflicting goals from the stand-point of Type I to III robust design across process chains. The variation embodies the introduction of specific robust design goals and constraints anchored in the mathematical constructs of error margin indices and design capability indices to determine “satisficing robust design” specifications for given performance requirement ranges using the goal-oriented, inverse design method. The design of a hot rolling process chain for the production of a rod is used as an example.
Hierarchical Combinatorial Design and Optimization of Quasi-Periodic Metamaterial Structures
Authors: Callanan Jesse , Ogunbodede Oladapo , Dhameliya Maulikkumar , Wang Jun , Rai Rahul
Published: November 2018

As advanced manufacturing techniques such as additive manufacturing become widely available, it is of interest to investigate the potential advantages that arise when designing periodic metamaterials to achieve a specific desired behavior or physical property. Designing the fine scale detailed geometry of periodic metamaterials to achieve a specified behavior falls under the category of notoriously intractable inverse problems. To simplify solving the inverse problem, most relevant works represent metamaterials as periodic single unit cell structures repeated in regular lattices. Such representation simplifies modeling and simulation task but at the cost of possibly limiting the range of physical behaviors that can be achieved through the use of more than one unit cell structures. This article outlines a quasi-periodic representation that utilizes more than a single unit cell to generate periodic metamaterials. Additionally, a hierarchical optimization scheme to optimize the generating function for a quasi-periodic structure using the genetic algorithm (GA) and a barrier function interior point method is also sketched to solve the inverse problem. To demonstrate the utility of the proposed hierarchical optimization framework to solve quasi-periodic metamaterial inverse problem, a problem in which the objective is to minimize the total strain in the structure while subjected to weight and the total-size constraint is considered. We detail the overall computational approach in which geometric representation, optimization algorithms, and finite element analysis are coupled and report preliminary numerical experiments.
Computational Design of a Personalized Artificial Spinal Disc for Additive Manufacturing With Physiological Rotational Motions
Authors: Yu Zhiyang , Stanković Tino , Shea Kristina
Published: November 2018

Due to the limitations of currently available artificial spinal discs stemming from anatomical unfit and unnatural motion, patient-specific elastomeric artificial spinal discs are conceived as a promising solution to improve clinical results. Multimaterial Additive Manufacturing (AM) has the potential to facilitate the production of an elastomeric composite artificial disc with complex personalized geometry and controlled material distribution. Motivated by the potential combined advantages of personalized artificial spinal discs and multi-material AM, a biomimetic multi-material elastomeric artificial disc design with several matrix sections and a crisscross fiber network is proposed in this study. To determine the optimized material distribution of each component for natural motion restoration, a computational method is proposed. The method consists of automatic generation of a patient-specific disc Finite Element (FE) model followed by material property optimization. Biologically inspired heuristics are incorporated into the optimization process to reduce the number of design variables in order to facilitate convergence. The general applicability of the method is verified by designing both lumbar and cervical artificial discs with varying geometries, natural rotational motion ranges, and rotational stiffness requirements. The results show that the proposed method is capable of producing a patient-specific artificial spinal disc design with customized geometry and optimized material distribution to achieve natural spinal rotational motions. Future work focuses on extending the method to also include implant strength and shock absorption behavior into the optimization as well as identifying a suitable AM process for manufacturing.
Energy Harvesting for Nuclear Waste Sensing and Monitoring
Authors: Wu Yongjia , Klein Jackson , Zhou Hanchen , Zuo Lei
Published: November 2018

Monitoring the parameters inside enclosed metal vessels or thick concrete walls as found in dry storage canisters and nuclear reactor vessels is crucial to ensuring safe reactor operation and fuel security. In this paper, two energy harvesters, namely the gamma radiation energy harvester and the thermal energy harvester, were built to power the wireless through-wall and communications for in-situ monitoring of interior conditions in nuclear canisters. The gamma radiation energy harvester was found to have an energy output of 17.8 mW during the first-year canister storage. However, this energy harvester was burdensome, and the performance deteriorates rapidly with time. The thermal energy harvester was thought to be a more practical solution. The power output of the energy harvester was about 93.9 mW in simulation and 46.3 mW in the experiment after 50-years storage in the canister. The power output of this energy harvester can be further scaled by adding TEGs at the cost of larger size.
Analyzing the Effect of Air Capacitor Turbocharging Single Cylinder Engines on Fuel Economy and Emissions Through Modeling and Experimentation
Authors: Buchman Michael R. , Johnson W. Brett , Winter Amos G.
Published: November 2018

Turbocharging can provide a cost effective means for increasing the power output and fuel economy of an internal combustion engine. A turbocharger added to an internal combustion engine consists of a coupled turbine and compressor. Currently, turbocharging is common in multi-cylinder engines, but it is not commonly used on single-cylinder engines due to the phase mismatch between the exhaust stroke (when the turbocharger is powered) and the intake stroke (when the engine intakes the compressed air). The proposed method adds an air capacitor, an additional volume in series with the intake manifold, between the turbocharger compressor and the engine intake, to buffer the output from the turbocharger compressor and deliver pressurized air during the intake stroke. This research builds on previous work where it was shown experimentally that a power gain of 29% was achievable and that analytically a power gain of 40–60% was possible using a turbocharger and air capacitor system.

The goal of this study is to further analyze the commercial viability of this technology by analyzing the effect of air capacitor turbocharging on emissions, fuel economy, and power density. An experiment was built and conducted that looked at how air capacitor sizing affected emissions, fuel economy, and the equivalence ratio. The experimental data was then used to calibrate a computational model built in Ricardo Wave. Finally this model was used to evaluate strategies to further improve the performance of a single cylinder diesel turbocharged engine with an air capacitor.
Teaching Design Freedom: Exploring the Effects of Design for Additive Manufacturing Education on the Cognitive Components of Students’ Creativity
Authors: Prabhu Rohan , Miller Scarlett R. , Simpson Timothy W. , Meisel Nicholas A.
Published: November 2018

Design for manufacturing provides engineers with a structure for accommodating the limitations of traditional manufacturing processes. However, little emphasis is typically given to the capabilities of processes that enable novel design geometries, which are often a point of focus when designing products to be made with additive manufacturing (AM) technologies. In addition, limited research has been conducted to understand how knowledge of both the capabilities (i.e., opportunistic) and limitations (i.e., restrictive aspects) of AM affects design outcomes. This study aims to address this gap by investigating the effect of no, restrictive, and both, opportunistic and restrictive (dual) design for additive manufacturing (DfAM) education on engineering students’ creative process. Based on the componential model of creativity [1], these effects were measured through changes in (1) motivation and interest in AM, (2) DfAM self-efficacy, and (3) the emphasis given to DfAM in the design process. These metrics were chosen as they represent the cognitive components of ‘task-motivation’ and ‘domain relevant skills’, which in turn influence the learning and usage of domain knowledge in creative production. The results of the study show that while the short (45 minute) DfAM intervention did not significantly change student motivation and interest towards AM, students showed high levels of motivation and interest towards AM, before the intervention. Teaching students different aspects of DfAM also resulted in an increase in their self-efficacy in the respective topics. However, despite showing a greater increase in self-efficacy in their respective areas of training, the students did not show differences in the emphasis they gave to these DfAM concepts, in the design process. Further, students from all three education groups showed higher use of restrictive concepts, in comparison to opportunistic DfAM.
Treating Epistemic Uncertainty Using Bootstrapping Selection of Input Distribution Model for Confidence-Based Reliability Assessment
Authors: Moon Min-Yeong , Choi K. K. , Gaul Nicholas , Lamb David
Published: November 2018

To accurately predict the reliability of a physical system under aleatory (i.e., irreducible) uncertainty in system performance, a very large number of physical output test data is required. Alternatively, a simulation-based method can be used to assess reliability, but it remains a challenge as it involves epistemic (i.e., reducible) uncertainties due to imperfections in input distribution models, simulation models, and surrogate models. In practical engineering applications, only a limited number of tests are used to model input distribution. Thus, estimated input distribution models are uncertain. As a result, estimated output distributions, which are the outcomes of input distributions and biased simulation models, and the corresponding reliabilities also become uncertain. Furthermore, only a limited number of output testing is used due to its cost, which results in epistemic uncertainty. To deal with epistemic uncertainties in prediction of reliability, a confidence concept is introduced to properly assess conservative reliability by considering all epistemic uncertainties due to limited numbers of both input test data (i.e., input uncertainty) and output test data (i.e., output uncertainty), biased simulation models, and surrogate models. One way to treat epistemic uncertainties due to limited numbers of both input and output test data and biased models is to use a hierarchical Bayesian approach. However, the hierarchical Bayesian approach could result in an overly conservative reliability assessment by integrating possible candidates of input distribution using a Bayesian analysis. To tackle this issue, a new confidence-based reliability assessment method that reduces unnecessary conservativeness is developed in this paper. In the developed method, the epistemic uncertainty induced by a limited number of input data is treated by approximating an input distribution model using a bootstrap method. Two engineering examples are used to demonstrate that 1) the proposed method can predict the reliability of a physical system that satisfies the user-specified target confidence level and 2) the proposed confidence-based reliability is less conservative than the one that fully integrates possible candidates of input distribution models in the hierarchical Bayesian analysis.
Geometric Design With Multiple Realizable Motion Directions in the Vicinity of a Planar Mechanism-Environment Contact
Authors: Robson Nina , Chen Binyun
Published: November 2018

This paper applies geometric design principles to planar mechanical systems, attempting to explain complex motion in mechanism-(virtual) object/environment interaction for achieving a variety of kinematic tasks in the vicinity of a contact location, a critical feature not fully captured in existing design methodologies. This is realized through the development of a general planar mechanism-object/environment geometric model, that allows the derivation of multiple velocity and acceleration specifications imposed by contact with (virtual) objects/environment. By incorporating these higher order kinematic specifications into the design task formulation, contemporary planar kinematic synthesis could be generalized allowing robust designs. The kinematic synthesis of planar RR and four-bar linages to follow two different paths in the vicinity of a mechanism-object contact location is used to illustrate the results.
Symbols for Computer Aided Design Software Operations: Selection and Effect on User Retention
Authors: Hubbert Mark , Alcantara David , Chang Ji Min , Choi Brian , Massey Caroline , Musselman Patrick , Morrill Timothy , Wang Andrew , Fuge Mark
Published: November 2018

Computer Aided Design (CAD) software can be difficult to learn. A major contributor to this entry barrier is CAD interfaces’ usage of symbols associated with CAD operations. This paper studies which symbols minimize recall time and optimize retention via two studies. We performed an initial exploratory study to identify which 2D symbols intuitively describe common CAD operations. Then we conducted a second study with three separate groups using different input methods to test which input method improves retention and recall time. Each group used one of three input methods: choosing preexisting Autodesk CAD operation symbols, choosing our 2D symbols derived from the symbol study, and physically drawing those same symbols. We measured participants’ accuracy and time spent on each question. The results indicated that there is a decrease in the time taken to submit responses, which correlates to recall time. The group physically drawing the symbols improved the most compared to the group selecting the symbol study symbols and the group selecting Autodesk operation icons. For retention, as measured by correctness, our statistical analysis indicates that there does not appear to be a significant difference between the three groups.
A Density Gradient Approach to Topology Optimization Under Design-Dependent Boundary Loading
Authors: Wang Cunfu , Qian Xiaoping
Published: November 2018

The paper proposes a density gradient based approach to topology optimization under design-dependent boundary loading. In the density-based topology optimization method, we impose the design dependent loads through spatial gradient of the density. We transform design-dependent boundary loads into a volume form through volume integral of density gradient. In many applications where loadings only need to be exerted on partial boundary, we introduce an auxiliary loading density to keep track of the loading boundary. During the optimization, the loading density is updated by tracking the changes of the physical density in the vicinity of the loading boundary at previous iteration. The proposed approach is easy to implement and computationally efficient. In addition, by adding more auxiliary density fields, the proposed approach is applicable to multiple design-dependent loads. To prevent the intersection of different loading boundaries, a Heaviside projection based integral constraint is developed. Both heat conduction problems under convection loading and elastic problems under hydrostatic pressure loading are presented to illustrate the effectiveness and efficiency of the method.