bluuebunny/crossref_metadata_2025 huggingface dataset:
Motion Analysis and Experiments of Reducer-Integrated Motor Using Strain Wave Gearing System
Authors: Terakawa Tatsuro , Komori Masaharu , Morita Yuya
Published: November 2018

Industrial robots need motors with high-precision positioning, large torque output, and small size. However, the conventional motors combined with reducers tend to be large. To solve the problem, we proposed the motor integrated with reducer that could output reduced rotation directly by using the strain wave gearing system. The proposed motor is thought to have advantages not only in downsizing but also in high load-supporting capacity and high stiffness because of the simultaneous engagement of three gear pairs. In this paper, we derive the theoretical input-output relation in the proposed motor with a focus on the deformation of the elastic gear in the motor. The result gives the pushing force of the linear actuators at an arbitrary output rotation angle of the motor. We conduct the experiments to clarify the optimal input pattern for the accurate rotation by using the prototype of the proposed motor. Through the observation and measurement, the optimal input pattern is suggested.
Operational and Strategic Decisions in Engineering Design Games
Authors: Grogan Paul T. , Bayrak Alparslan Emrah
Published: November 2018

Engineering design games model decision-making activities by incorporating human participants in an entertaining platform. This article distinguishes between design decisions at operational and strategic timescales as important features of engineering design games. Operational decisions consider static and short-term dynamic decisions to establish a player’s situation awareness and initial entertainment. Strategic decisions consider longer-term dynamic decisions subject to large uncertainties to retain player engagement. However, constraints on cognitive load limit the ability to simultaneously address both lower-level operational design decisions and higher-level strategic decisions such as collaboration or sustainability. Partial automation can be introduced to reduce cognitive load for operational decisions and focus additional effort on strategic decisions. To illustrate tradeoffs between operational and strategic decisions, this paper discusses example cases for two existing games: Orbital Federates and EcoRacer. Discussion highlights the role of automation and entertainment in engaging human participants in engineering design games and makes recommendations for design of future engineering design games.
Exploiting the Kinematic Redundancy of a 6+3 Dofs Parallel Mechanism
Authors: Schreiber Louis-Thomas , Gosselin Clément
Published: November 2018

This paper presents trajectory planning methods for a kinematically redundant parallel mechanism. The architecture of the mechanism is similar to the well-known Gough-Stewart platform and it retains its advantages, i.e., the members connecting the base to the moving platform are only subjected to tensile/compressive loads. The kinematic redundancy is exploited to avoid singularities and extend the rotational workspace. The architecture is described and the associated kinematic relationships are presented. Solutions for the inverse kinematics are given, as well as strategies to take into account the limitations of the mechanism such as mechanical interferences and velocity limits of the actuators while controlling the redundant degrees of freedom.
Knowledge Assisted Optimization for Large-Scale Problems: A Review and Proposition
Authors: Wu Di , Wang G. Gary
Published: November 2018

In engineering design, engineers often have certain knowledge about the design problem. However, in the last decades, we assume design functions are black-boxes. This paper discusses if knowledge can help with optimization, especially for large-scale optimization problems. Existing large-scale optimization methods based on black-box functions are first reviewed and the drawbacks of those methods are briefly discussed. To understand what knowledge is and what kinds of knowledge can be obtained and applied in design, the concepts of knowledge in both artificial intelligence (AI) and in the area of product design are reviewed. The relevant knowledge based engineering (KBE) system is also explained. Existing applications of knowledge in optimization, especially for large-scale optimization, are reviewed and categorized. Potential further applications of incorporating knowledge for optimization are discussed in more detail, in hope to identify possible directions for future research for knowledge assisted optimization.
Multi-Fidelity Modeling and Adaptive Co-Kriging Based Optimization for All-Electric GEO Satellite Systems
Authors: Shi Renhe , Liu Li , Long Teng , Wu Yufei , Wang G. Gary
Published: November 2018

All-electric GEO satellite systems design is a challenging multidisciplinary design optimization (MDO) problem, which is computation-intensive due to the employment of expensive simulations. In this paper, the all-electric GEO satellite MDO problem with multi-fidelity models is investigated. The MDO problem involving six inter-coupled disciplines is formulated to minimize the total mass of the satellite system subject to a number of engineering constraints. To reduce the computational cost of the multidisciplinary analysis (MDA) process, multi-fidelity transfer dynamics models and finite element analysis (FEA) models are developed for the geosynchronous transfer orbit (GTO) and structure disciplines respectively. To effectively solve the all-electric GEO satellite MDO problem using multi-fidelity models, an adaptive Co-Kriging based optimization framework is proposed. In this framework, the samples from a high-fidelity MDA process are integrated with those from a low-fidelity MDA process to create a Co-Kriging metamodel with moderate computational cost for optimization. Besides, for refining the Co-Kriging metamodels, a multi-objective adaptive infill sampling approach is developed to produce the infill sample points in terms of expected improvement (EI) and probability of feasibility (PF) functions. Optimization results show that the proposed optimization framework can significantly reduce the total mass of satellite system with limited computational budget, which demonstrates the effectiveness and practicality of the multi-fidelity modeling and adaptive Co-Kriging based optimization framework for all-electric GEO satellite systems design.
Differential Quadrature Discrete Time Transfer Matrix Method for Vibration Mechanics
Authors: He Bin , Long Jin
Published: November 2018

Transfer matrix method is a practical technology for vibration analysis of engineering mechanics. In this paper, Differential Quadrature Discrete Time–Transfer Matrix Method (DQ-DT-TMM) is presented for solving vibration mechanics. Firstly ordinary differential equations of the sub-structure or the element of the mechanical system are determined by classical mechanics rule and transformed as a set of algebraic equations at some discrete time points by the application of differential quadrature method. Then by extending the state vector of transfer matrix method, new transfer equations and transfer matrices of the sub-structures of the mechanical system are developed. The Riccati transform can be used to improve the computational convergence of the method. Several numerical examples show the proposed method can be regarded as an efficient tool for transient response analysis of vibration system.
Extraction of Surfaces Using Section Curves for Engineering Plants
Authors: Midorikawa Yoshitaka , Masuda Hiroshi
Published: November 2018

For simulating renovation of industrial facilities, 3D models are very useful. However, it is time-consuming to create 3D models. The terrestrial laser scanner is effective for easily capturing 3D data of large-scale facilities. So far, many researchers have proposed methods for reconstructing pipe structures in industrial plants using point-clouds. In those methods, planes and cylinders are extracted from point-clouds, but they are not enough for creating various types of equipment. Especially, in manufacturing plants for liquids and gases, rotating surfaces and generalized cylinders are typically used as well as planes and cylinders. In this paper, this paper proposes methods for extracting rotating surfaces and generalized cylinders from noisy and incomplete point-clouds. Since the section shapes of rotating surfaces and generalized cylinders are approximately ellipses, this method detects elliptic section shapes from point-clouds. Then rotating surfaces and generalized cylinders are reconstructed by extracting the center curves and section circles. Then the authors combine this method with general-purpose voxel-based shape reconstruction methods. Since this method is robust to missing points caused by occlusion, the quality of shape reconstruction can be improved even if points are partly missing due to occlusion.
Product Architecture Transition in a Modular Cyber-Physical Truck
Authors: Williamsson David , Sellgren Ulf , Söderberg Anders
Published: November 2018

A modular product architecture is a strategic means to deliver external variety and internal commonality. In this paper, we propose a new clustering based method for product modularization that integrates product complexity and company business strategies. The proposed method is logically verified by a studied industrial case, where the architecture of a heavy truck driveline is analyzed in terms of how it has evolved over a couple of decades, due to changed business strategies and the evolution of new technology. The presented case indicates that the new methodology is capable of identifying and proposing reasonable module candidates that address product complexity as well as company-specific strategies. Furthermore, the case study clearly shows that the business strategic reasons for a specific architecture can be found by analyzing how sensitive the clusters are to changes in the module drivers.
Introducing a Projection-Based Method to Compare Three Approaches Computing the Accumulation of Geometric Variations
Authors: Delos Vincent , Arroyave-Tobón Santiago , Teissandier Denis
Published: November 2018

In mechanical design, tolerance zones and contact gaps can be represented by sets of geometric constraints. For computing the accumulation of possible manufacturing defects, these sets have to be summed and/or intersected according to the assembly architecture. The advantage of this approach is its robustness for treating even over-constrained mechanisms i.e. mechanisms in which some degrees of freedom are suppressed in a redundant way. However, the sum of constraints, which must be computed when simulating the accumulation of defects in serial joints, is a very time-consuming operation. In this work, we compare three methods for summing sets of constraints using polyhedral objects. The difference between them lie in the way the degrees of freedom (DOFs) (or invariance) of joints and features are treated. The first method proposes to virtually limit the DOFs of the toleranced features and joints to turn the polyhedra into polytopes and avoid manipulating unbounded objects. Even though this approach enables to sum, it also introduces bounding or cap facets which increase the complexity of the operand sets. This complexity increases after each operation until becoming far too significant. The second method aims to face this problem by cleaning, after each sum, the calculated polytope to keep under control the effects of the propagation of the DOFs. The third method is new and based on the identification of the sub-space in which the projection of the operands are bounded sets. Calculating the sum in this sub-space allows reducing significantly the operands complexity and consequently the computational time. After presenting the geometric properties on which the approaches rely, we demonstrate them on an industrial case. Then we compare the computation times and deduce the equality of the results of all the methods.
Dynamic Model Discrepancy Quantification in Simulation-Based Design of Dynamical Systems
Authors: Hu Zhen , Hu Chao , Mourelatos Zissimos P. , Mahadevan Sankaran
Published: November 2018

Discrete-time state-space models have been extensively used in simulation-based design of dynamical systems. These prediction models may not accurately represent the true physics of a dynamical system due to potentially flawed understanding of the system, missing physics, and/or numerical approximations. To improve the validity of these models at new design locations, this paper proposes a novel dynamic model discrepancy quantification (DMDQ) framework. Time-instantaneous prediction models are constructed for the model discrepancies of “hidden” state variables and are used to correct the discrete-time prediction models at each time step. For discrete-time models, the “hidden” state variables and their discrepancies are coupled over two adjacent time steps. Also, the state variables cannot be directly measured. These factors complicate the construction of the model discrepancy prediction models. The proposed DMDQ framework overcomes these challenges by proposing two discrepancy modeling approaches: an estimation-modeling approach and a modeling-estimation approach. The former first estimates the model discrepancy and then builds a non-parametric prediction model of the model discrepancy; the latter builds a parametric prediction model of the model discrepancy first and then estimates the parameters of the prediction model. A subsampling method is developed to reduce the computational effort in building the two types of prediction models. A mathematical example and an electrical circuit dynamical system demonstrate the effectiveness of the proposed DMDQ framework and highlight the advantages and disadvantages of the proposed approaches.
Minimization of Cost and Print Time of Additive Manufacturing via Topology Optimization
Authors: Sabiston Graeme , Ryan Luke , Kim Il Yong
Published: November 2018

As the field of design for additive manufacturing continues to evolve and accelerate towards admitting more robust designs requiring fewer instances of user-intervention, we will see the conventional design cycle evolve dramatically. However, to fully take advantage of this emerging technology — particularly with respect to large scale manufacturing operations — considerations of productivity from a fiscal perspective are sure to become of the utmost importance. A mathematical model incorporating the cost and time factors associated with additive manufacturing processes has been developed and implemented as a multi-weighted single-objective topology optimization algorithm. The aforementioned factors have been identified as component surface area and volume of support material. These quantities are optimized alongside compliance, producing a design tool that gives the user the option to choose the relative weighting of performance over cost. In two academic examples, minimization of compliance alongside surface area and support structure volume yield geometries demonstrating that considerable decreases in support material in particular can be achieved without sacrificing significant part compliance.
Wrench Capability Analysis of Aerial Cable Towed Systems
Authors: Erskine Julian , Chriette Abdelhamid , Caro Stéphane
Published: November 2018

Aerial cable towed systems (ACTSs) can be created by joining unmanned aerial vehicles (UAVs) to a payload to extend the capabilities of the system beyond those of an individual UAV. This paper describes a systematic method of evaluating the available wrench set and the robustness of equilibrium of ACTSs by adapting wrench analysis techniques used in cable-driven parallel robots to account for the constraints of quadrotor actuation. Case studies are provided to demonstrate the analysis of different classes of ACTSs, as a means of evaluating the design and operating configurations.
Advanced Primal-Dual Interior-Point Method for the Method of Moving Asymptotes
Authors: Li Daozhong , Roper Stephen , Kim Il Yong
Published: November 2018

The Method of Moving Asymptotes (MMA) is one of the well-known optimization algorithms for topology optimization due to its stable numerical performance. Here, this paper simplifies the MMA algorithm by considering the features of topology optimization problem statements and presents a strategy to solve the necessary subproblems based on the primal-dual-interior-point method to further enhance numerical performance. A new scaling mechanism is also introduced to improve searching quality by utilizing the sensitivities of the original problems at the beginning of each MMA iteration. Numerical examples of solving both mathematical problems and topology optimization problems demonstrate the success of this method.
Flexibility in Upper Limb Rehabilitation With the Use of 1-DOF Fourbar Linkages
Authors: Kurmashev Sabit , Ospanov Sayat , Malik Aryslan , Xydas Evagoras , Mueller Andreas
Published: November 2018

In robotic rehabilitation the interaction is usually implemented by means of robots based on multi-Degree of Freedom (DOF) open kinematic chains. Despite their inherent flexibility these machines are expensive, complex and require routine maintenance and IT support. In contrast, mechanisms based on closed kinematic chains and especially 1-DOF four- and six bar linkages are simple, yet capable of generating paths with complex kinematic characteristics. These mechanisms are preferable when simplicity and cost are the major criteria, for example in the case of community-based rehabilitation in developing countries. On the other hand, rehabilitation using 1-DOF limits flexibility and potentially impairs the exercise effectiveness, since the patient does not have access to a variety of kinematic challenges. Nevertheless, by careful ergonomic design and by considering varying time constraints, link rotation ranges and varying link lengths this limitation can be overcome. This work aims to demonstrate the potential of 1-DOF four-bar linkages to provide flexibility in therapy by considering a Hoeken’s straight line four-bar linkage. After the mechanism is dimensioned, a previously developed method is employed for establishing a final prototype design which accounts for significant neurophysiological models such as Minimum Jerk Model, Fitts’s Law and Just Noticeable Differences. Given the mechanism characteristics, its potential for generation of exercises that vary with respect to temporal and spatial characteristics is demonstrated.
Concurrent Optimization of Structure Topology and Infill Properties With a Cardinal-Function-Based Parametric Level Set Method
Authors: Jiang Long , Chen Shikui , Wei Peng
Published: November 2018

In this paper, a parametric level-set-based topology optimization framework is proposed, to concurrently optimize structural topology at the macroscale as well as the infill material properties at the mesoscale. With the parametric level set framework, both the boundary evolution and the material property optimization during the optimization process are driven by the Method of Moving Asymptotes (MMA) optimizer, which is more efficient than the PDE-driven level set approach when handling nonlinear problems with multiple constraints. Rather than using a radial basis function (RBF) for the level set parameterization, a new type of cardinal basis function (CBF) was constructed as the kernel function for the proposed parametric level set approach. With this CBF kernel function, the bounds of the design variables can be defined explicitly, which is a great advantage compared with the RBF-based level set method. A variational approach was conducted to regulate the level set function to be a distance-regularized shape for a better material property interpolation accuracy and higher design robustness. With the embedded distance information from the level set model, boundary layer and the infill can be naturally discriminated.
Stochastic Switching and Reduction of Integrity in Atomic Force Microscopy
Authors: Belardinelli Pierpaolo , Lenci Stefano , Alijani Farbod
Published: November 2018

In the presence of more than one stable state, assessment of stability is crucial for a proper device characterization. This is of particular importance in atomic force microscopy due to rich dynamics exhibited by the oscillating microcantilever probe that interacts with a sample. Indeed, the multistability can evolve in dramatic regime changes. This work aims at investigating the stochastic switching in which perturbations are responsible for shifts between alternative states with consequences in imaging and spectroscopy. The deceptively straightforward identification of the stability highlights noise-activated escapes. The barrier crossing from metastable wells in the atomic force microscopy leading to problematic configurations are observed in a variety of different configurations with the stochastic resonance as ultimate condition. Our analysis sheds light on the effect of combined additive noise and external excitation. The noise-induced erosion of the attractive domain shows a progressive reduction of the dynamical integrity of amplitude modulation atomic force microscopes.
Uncertainty Analysis of a Francis Hydropower Unit
Authors: Dourado Arinan De P. , Barbosa Jefferson S. , Morais Tobias S. , Cavalini Aldemir Ap , Steffen Valder
Published: November 2018

This contribution is dedicated to the analysis of uncertainties affecting the vibration responses of a Francis hydropower unit. The system is composed by a vertical rotor and three hydrodynamic bearings: i) a combined tilting-pad guide/thrust bearing, located close to the generator; ii) an intermediate radial tilting-pad bearing; iii) and a cylindrical bearing located close to the Francis turbine. The bearings are represented by using linearized stiffness and damping coefficients. A fuzzy uncertainty analysis was applied aiming at determining the extreme vibration responses of the system. In this case, the bearings stiffness coefficients, generator mass, and Young’s modulus of the shaft were considered as uncertain information. The fuzzy analysis was carried out through the so-called α-level optimization approach due to its mathematical simplicity. Finally, a sensitivity analysis was performed based on the obtained results to determine the uncertain parameters that most affect the rotor responses. The obtained results demonstrate the representativeness of the conveyed methodology.
Rigid Body Dynamic Simulation With Multiple Convex Contact Patches
Authors: Xie Jiayin , Chakraborty Nilanjan
Published: November 2018

We present a principled method for dynamic simulation of rigid bodies in intermittent contact with each other where the contact is assumed to be a non-convex contact patch that can be modeled as a union of convex patches. The prevalent assumption in simulating rigid bodies undergoing intermittent contact with each other is that the contact is a point contact. In recent work, we introduced an approach to simulate contacting rigid bodies with convex contact patches (line and surface contact). In this paper, for non-convex contact patches modeled as a union of convex patches, we formulate a discrete-time mixed complementarity problem where we solve the contact detection and integration of the equations of motion simultaneously. Thus, our method is a geometrically-implicit method and we prove that in our formulation, there is no artificial penetration between the contacting rigid bodies. We solve for the equivalent contact point (ECP) and contact impulse of each contact patch simultaneously along with the state, i.e., configuration and velocity of the objects. We provide empirical evidence to show that if the number of contact patches between two objects is less than or equal to three, the state evolution of the bodies is unique, although the contact impulses and ECP may not be unique. We also present simulation results showing that our method can seamlessly capture transition between different contact modes like non-convex patch to point (or line contact) and vice-versa during simulation.
Holistic Modeling and Optimization of Electric Vehicle Powertrains Considering Longitudinal Performance, Vehicle Dynamics, Costs and Energy Consumption
Authors: Angerer Christian , Krapf Sebastian , Buß Alexander , Lienkamp Markus
Published: November 2018

The authors provide a copious literate review on powertrain design optimization for electric vehicle (EV) powertrains. The review shows a gap in the state of science regarding the consideration of all customer relevant requirements. Existing approaches either focus on performance and energy consumption or concentrate on vehicle dynamics.

Based on this insight, the authors analyze customer requirements and derive all vehicle properties that are influenced by the powertrain concept. They find that costs, longitudinal performance, lateral dynamics, off-road capabilities and energy consumption are key vehicle properties. The powertrain concept affects all these properties and thus determines the satisfaction of customer requirements.

Subsequently the authors describe a vehicle simulation model that represents all predefined customer requirements in dependence on the powertrain concept design.
Design and Analysis of a Novel 6-URS Self-Reconfigurable All-Dimensional Walking Robot
Authors: Li Yanwen , Qi Zhaoxu , Mao Pengfei , Sun Wenlong , Jiao Juan , Zhu Weiguo
Published: November 2018

This paper presents a novel 6-URS self-reconfigurable all-dimensional walking robot. The model of the 6-URS self-reconfigurable walking robot is established, then its reconfiguration modes are proposed. Based on the screw theory, the degrees of freedom (DOF) of this robot before and after reconfiguration are analysed separately to verify the feasibility of self-reconfiguration. This robot can achieve self-reconfigurable function with the design of self-reconfigurable limbs. Moreover, the trajectory planning and simulation of three kinds of gaits are performed, including walking horizontally, turning and climbing. The above analysis shows that the 6-URS self-reconfigurable all-dimensional robot satisfies the walking requirements and has the reconfigurable ability in unstrcutured environment.
Research on Dynamic Shift Rule of Agricultural Tractor PST Based on Maximum Productivity
Authors: Xi Zhiqiang , Wu Zhenqing , Li Zhongli , Li Jishun
Published: November 2018

When worked in field traction operation, the productivity index of the tractor unit is mainly reflected by the traction performance. Through analyzing the influence factors of the maximum productivity and the traction characteristics of tractor when equipped with automatic power-shift transmission, it is determined that the improvement of traction power of tractor is the fundamental measure to obtain the maximum productivity. Based on the principle, the dynamic gearshift rule and its control strategy are presented, which takes the throttle opening and engine speed as control parameters. Taking YTO LA2004 wheeled tractor as investigative subject, the simulation analysis of heavy load working condition such as ploughing was carried out. The results show that the maximum productivity shift rule can be used to shift the transmission gear with the change of traction load, which ensure that the engine works at speed governing line near the maximum power point, it can improve the traction power and traction efficiency of tractor. And when the load is small fluctuations, it doesn’t affect the change of gear, which can avoid the repeat gearshift phenomenon. The research provided a theoretical basis for the development of automatic transmission control system of tractor.
Modeling and Analysis of a Self-Steering Axle for Heavy Vehicles
Authors: Delorenzis Damon , Ayalew Beshah
Published: November 2018

Self-steering axles installed on commercial (heavy) vehicles offer important benefits, including improvements to vehicle performance such as off-tracking reduction and improved maneuverability, as well as reduction in pavement wear and damage that otherwise can result from the operation of heavy vehicles on the roadway. Traditional design methods for self-steering axles include empirical and trial-and-error methods to set steering mechanism design parameters based on known design baselines and prior experience. While the design of self-steering axles has not changed very much since their introduction, increasingly regulations and competitive market pressures have promoted the need for new designs to improve the performance of self-steering axles and differentiate new product offerings such as a new integrated steering knuckle concept which provides steering return stiffness and damping using a non-traditional design.

This paper introduces models useful in the analysis of the steering return stiffness and damping performance of self-steering axle systems and shows how to identify the steering stiffness and damping characteristics that provide acceptable performance for these systems. The paper offers reduced order models that capture the self-steering axle’s shimmy behavior and discusses how to arrive at acceptable steering and damping characteristics. It presents results of the evaluations of the steering system performance including with comparisons between physical testing and simulations with a self-steering axle installed on a commercial vehicle.
A Triboelectric Nanogenerator (TENG) for Pipeline Monitoring
Authors: Das M. Taylan , Murugan Kavinaath , Tetreault Adam , Irvine Connor , Rosic Andrej , Saritas Resul , Yavuz Mustafa , Abdel-Rahman Eihab M.
Published: November 2018

In this study, we present triboelectric nanogenerators (TENGs) for vibrational energy harvesting in oil pipelines. The generators are designed to replenish the batteries of leak detection sensor, thereby increasing their lifespan and reducing the need for maintenance. The TENGs were designed to harvest energy from a 12-inch diameter pipeline, vibrating with at 32 Hz. Three alternative materials were used for the upper plate of a 4 × 4 cm TENG, namely Polytetrafluoroethylene (PTFE), unstructured polydimethylsiloxane (PDMS) and structured PDMS. Tests revealed that the unstructured PDMS TENG outperformed the PTFE TENG and generated 47.6 μW of power. Structuring the PDMS by patterning open channels on half of the surface increased the output power to 200.0 μW. When the spring constant of the structured PDMS TENG was optimized, the output power was further increased to 297.7 μW. These results demonstrate that structured PDMS shows promise in triboelectric energy harvesting, specifically because it can be surface-modified using inexpensive techniques that do not require a clean room.
MEMS Based Differential Scanning Calorimeter for Biomolecular Study
Authors: Yu Shifeng , Wang Shuyu , Lu Ming , Zuo Lei
Published: November 2018

This paper presented a MEMS based differential scanning calorimeter (DSC) for biomolecular characterization. In this MEMS based DSC, PDMS (Polydimethylsiloxane) and Flexdyne thin film were used to construct the microfluidic chamber. Polyimide were used to fabricate the flexible substrate and temperature sensitive vanadium oxide was used as the thermistor material. A heating stage was used to heat the sample and reference up at a certain rate. The resolution study and step response characterization indicated the high sensitivity (6.1V/W) of the device. The test with Bovine Serum Albumin (BSA) samples showed clear phase transitions and the data was confirmed to be reasonable by comparing it with the results of commercial DSC’s test. This device used 0.63uL sample amount and could complete the scanning process in 3 minutes, significantly increasing the throughput of the biomolecular thermodynamics study like protein denaturation process compared to the traditional DSC (1 to 2 hours).
Data-Driven Probabilistic Thermal Stress Analysis of a Gas Turbine Casing
Authors: Han Zixi , Li Mian , Jiang Zixian , Min Zuoxing , Bourmich Sophie
Published: November 2018

Strength requirement is one of the most important criteria in the design of gas turbine casing. Traditionally, deterministic analyses are used in strength assessment, with boundary conditions and loads set as fixed design values. However, real boundary conditions and loads in the operation can often differ from the fixed design values, such that the mechanical integrity of the turbine casing can vary from the strength and fatigue calculations.

In this work, the effect of the variability of the boundary conditions and loads is investigated on the static thermal stress problem of gas turbine casings using a probabilistic approach. The probability distribution is estimated using a Monte Carlo simulation based on the distribution of boundary conditions and loads obtained from field measurements. The finite element analysis is used to calculate the stress corresponding to different boundary conditions and a surrogate model is built to reduce the computational time of Monte Carlo simulations. This methodology is applied to a real engineering case which better quantifies the strength assessment result.
Driving Performance of Natural Fiber Gears Made From Only Bamboo Fibers Extracted With a Machining Center
Authors: Yanagawa Takayuki , Hirogaki Toshiki , Aoyama Eiichi , Matsui Syota , Nobe Hiromichi
Published: November 2018

The advantages of a plastic gear are that it is light and can be used without any lubricant, and its disadvantages are that its strength is low and it has large environmental impact. Therefore, the development of a new gear that maintains the advantages while negating the disadvantages has been proposed. The development of sustainable and reproducible natural materials is particularly desired to address environmental problems. Therefore, in this study, a method was devised to extract high quality and highly precise bamboo fibers using a machining center. Then, the hot press method was used to produce a spur gear, which is a machine element with a complicated shape. The present paper describes the characteristics of the bamboo fiber gears investigated through experiments. The results of tooth root strain measurement showed the relationship between rotation speed and tooth root strain. In addition, we calculated the theoretical value of tooth root strain and compared it with the experimental value. The experimental value was lower than the calculated value. The results of acceleration measurement showed that that tooth root strain is associated with acceleration.
Lightweight Design of Three-Dimensional Woven Composite Automobile Shock Tower
Authors: Tao Wei , Zhu Ping , Liu Zhao , Chen Wei
Published: November 2018

This paper proposes a lightweight design strategy for automobile shock tower made of three-dimensional woven composites (3DWOC). The presented design strategy consists of an analytical model for predicting the mechanical behaviors of composites and an optimization method. Volume averaging method and iso-strain assumption are adopted in the analytical model to calculate the elastic properties and strength characteristics of 3DWOC. The predicted properties are in good agreement with the available experimental data. An optimization method integrating particle swarm optimization algorithm and surrogate modeling technique is employed to solve the optimization problem with mixed discrete-continuous design variables from material and structure. The optimized automobile shock tower meets all requirements on structural stiffness and strength when reaching a 30.27% weight reduction.
A Screw Approach to the Approximation of the Local Geometry of the Configuration Space and of the Set of Configurations of Certain Rank of Lower Pair Linkages
Authors: Müller Andreas
Published: November 2018

The determination of the finite mobility of a linkage boils down to the analysis of its configuration space (c-space). Since a global analysis is not feasible in general (but only for particular cases), the research focused on methods for a local analysis. Past research has in particular addressed the approximation of finite curves in c-space (i.e. finite motions). No universal method for the approximation of the c-space itself has been reported. In this paper a generally applicable formulation of the equations defining the higher-order local approximation of the c-space as well as the set of points where the Jacobian has a certain rank are presented. To this end, algebraic formulations of the higher-order differential of the constraint mapping (defining the loop closure) and of the Jacobian minors of arbitrary order are introduced. The respective local approximation is therewith given in terms of a low-order polynomial system. Results are shown for a simple planar 4-bar linkage and a planar three-loop linkage. Since the latter exhibits a cusp singularity it cannot be treated by the local analysis methods proposed thus far, which are based on approximating finite curves.
A New Sequential Robust Approach for MDO Problems Under Mixed Interval and Probabilistic Uncertainties
Authors: Xia Tingting , Li Mian
Published: November 2018

In the design process of complex multidisciplinary systems, uncertainties in parameters or variables cannot be ignored. Robust multidisciplinary design optimization methods (RMDOs) can treat uncertainties as specified probabilistic distributions when enough statistical information is available. RMDOs need to assign intervals for nondeterministic variables since some design quantities may not have enough information to obtain statistical distributions, especially in the early stage of a design optimization process. Both types of uncertainties are very likely to appear simultaneously. In order to obtain robust solutions for multidisciplinary design optimization problems under mixed interval and probabilistic uncertainties, this work proposed a new sequential robust MDO approach, mixed SR-MDO. First, the robust optimization problem in a single discipline under mixed uncertainties is formulated and solved. Then, following the SR-MDO framework in our early work, MDO problems under mixed uncertainties are solved by handling probabilistic and interval uncertainties sequentially in decomposed subsystem problems. Interval uncertainties are handled by using the worst-case sensitivity analysis and fixing probabilistic uncertainties at their mean first, and then the influence of probabilistic uncertainties in objectives, constraints as well as in discipline analysis models is characterized by corresponding mean and variance. The applied SR-MDO framework allows subsystems in its full autonomy robust optimization and sequential robust optimization stages to run independently in parallel. This makes mixed SR-MDO be efficient for independent disciplines to work simultaneously and be more time-saving. Computational complexity of the proposed approach mainly relates to the double-loop optimization process in the worst-case interval uncertainties analysis. Examples are presented to demonstrate the applicability and efficiency of the mixed SR-MDO approach.
Ontology-Based Unified Representation of Dynamic Simulation Models in Engineering Design
Authors: Yu Jun , Ming Zhenjun , Wang Guoxin , Yan Yan , Lan Xiaoping
Published: November 2018

The development of complex product dynamic simulation models and the integration of design automation systems require knowledge from multiple heterogeneous data sources and tools. Because of the heterogeneity of model data, the integration of tools and data is a time-consuming and error-prone task. The main objective of this study is to provide a unified model of dynamic simulation for engineering design, which serves as a knowledge base to support the development of a dynamic simulation model. The integration of knowledge is realized through (i) definition of the structure and interface during the design phase of the dynamic simulation model, and (ii) definition of a model-driven integrated environment configuration process during the runtime phase. In order to achieve interoperability among the different simulation models in a collaborative design environment, we build a “Demand-Resources-Service-Knowledge-Process (DKRSP)” ontology that formally represents the semantics of dynamic simulation models. Based on the ontology, a knowledge base is created for the management of dynamic simulation knowledge. The efficacy of the ontology and the knowledge base are demonstrated using a transmission design example.
Probability of Detection (POD)-Oriented View to Fault Diagnosis for Reliability Assessment of FDI Approaches
Authors: Ameyaw Daniel A. , Rothe Sandra , Söffker Dirk
Published: November 2018

Reliability assessment of Structural Health Monitoring systems applied to the diagnosis of faults in elastic structures is discussed in this contribution. In the field of Non Destructive Testing (NDT), Probability of Detection (POD) is used as a performance measure for quantifying the reliability of NDT approaches. However, reliability measures applied to Fault Detection and Isolation (FDI) is not discussed much in this research area. In this contribution the reliability of vibration-based monitoring approaches with respect to their principal ability to detect changes, realize diagnosis, and isolate causes (as FDI) is discussed. Using eigenfrequency and band power as attributes, a novel feature-based POD is proposed and implemented as a reliability measure for vibration-based FDI. The a90/95 criteria which represents 90% probability of detecting a fault with 95% level of confidence is successfully implemented to an experimentally realized monitoring system. Emphases is made on improving the detection quality through sensor/information fusion. Acceleration, strain, and deflection measurement paths are utilized for diagnosis purposes based on experimental results.
Triangulation Based Isogeometric Analysis of the Cahn-Hilliard Phase-Field Model
Authors: Zhang Ruochun , Qian Xiaoping
Published: November 2018

This paper presents the triangulation based isogeometric analysis of the Cahn–Hilliard phase-field model. We validate our method by convergence analysis, show detailed system evolution from a randomly perturbed initial condition and then discuss related isoperimetric problems. Lastly an example highlighting its efficacy in complex geometry is provided. Triangulation based isogeometric analysis shows time step stability and complex geometry adaptability in our experiments.
Design Opportunities for Sea Turtle Satellite Tracking Devices
Authors: Piacenza Joseph , Piacenza Susan , Mayoral Salvador , Kenney Alexia , Shields Nikolai
Published: November 2018

Satellite-linked platform terminal transmitters (PTTs) enable biologists to study movements of sea turtles. However, PTTs often fail due to limited battery life, antenna breakage, biofouling, saltwater switch failure, and premature tag detachment. Also, PTTs induce hydrodynamic drag and may bias sea turtle behavior. Advances in technology continue to improve PTTs, however, design opportunities remain so that deployment duration is increased and behavioral biases are limited. We review how PTTs are used to obtain information on sea turtle biology, the current state-of-the-art, review recent innovations and highlight potential areas for design improvements. There remain several areas to focus on design improvements: (1) improve attachment methods so as to stretch as juveniles grow but do not add additional height to tag profile, (2) improve tag profile and attachment location on the turtle carapace to limit hydrodynamic drag, (3) experiment with different energy harvesting options to extend deployment duration, and (4) improve antenna design and material to enhance robustness and transmission quality. Capitalizing on emerging technology that allows for increasing miniaturization will likely create tags that extend deployment duration and induce negligible behavioral biases and will create data that best represents the true biology of sea turtle species in-water.
Design Strategy Transfer in Cognitively-Inspired Agents
Authors: Raina Ayush , McComb Christopher , Cagan Jonathan
Published: November 2018

Planning and strategizing are essential parts of the design process and are based on the designer’s skill. Further, planning is an abstract skill that can be transferred between similar problems. However, planning and strategy transfer within design have not been effectively modeled within computational agents. This paper presents an approach to represent this strategizing behavior using a probabilistic model. This model is employed to select the operations that computational agents should perform while solving configuration design tasks. This work also demonstrates that this probabilistic model can be used to transfer strategies from human data to computational agents in a way that is general and useful. This study shows a successful transfer of design strategy from human-to-computer agents, opening up the possibility of deriving high-performing behavior from designers and using it to guide computational design agents. Finally, a quintessential behavior of transfer learning is illustrated by agents while transferring design strategies across different problems, improving agent performance significantly. The work presented in this study leverages a computational framework built by embedding cognitive characteristics into agents, which has shown to mimic human problem-solving in configuration design problems.
Rod Stress Prediction in Spinal Alignment Surgery With Different Supplementary Rod Constructing Techniques: A Finite Element Study
Authors: Xu Ming , Scholl Thomas , Berjano Pedro , Cruz Jazmin , Yang James
Published: November 2018

Rod fracture and nonunion are common complications associated with pedicle subtraction osteotomies (PSO). Supplementary rods and interbody cage (IB) are added to reduce the primary rod stress. As supplementary rods, delta rods and cross rods have been proposed to reduce more stress on the primary rods compared to conventional supplementary rods (accessary rods) in PSO. The objective of this study is to investigate the effects of cross rods and delta rods on reducing primary rod stress in PSO subject. A validated 3D finite element model of a T12-S1 spine segment with 25° PSO at L3 and bilateral rods fixation from T12-S1 was used to compare different rod configurations: 1) PSO and two primary rods (PSO+2P); 2) PSO with an IB at L2-L3 (PSO+2P+IB); 3) PSO with accessory rods and an IB at L2-L3 (PSO+2P+IB+2A); 4) PSO with delta rods and an IB at L2-L3 (PSO+2P+IB+2D); 5) PSO with single cross rod and an IB at L2-L3 (PSO+2P+IB+1C); 6) PSO with double cross rods and an IB at L2-L3 (PSO+2P+IB+2C). The spine model was loaded with a follower load of 400 N combined with pure moments of 7.5 Nm in flexion, extension, right lateral bending, and right axial rotation. Von Mises stress of the primary rods were predicted for all test conditions. The PSO without IB condition had the largest primary rod stress in flexion. With IB at L2-L3, the rod stress in flexion reduced by 15%. Adding 2 conventional supplementary rods reduced the rod stress in flexion by 29%, which was achieved by adding single cross rod. The maximum von Mises stress occurred in the middle of the primary rods without supplementary rods whereas the maximum stress concentrated adjacent to the contact region between the connectors and the primary rods. Delta rods and double cross rods reduced the most rod stress in flexion, which were by 33% and 32% respectively. Under lateral bending, 2 delta rods reduced the most primary rod stress (−33%). Under axial rotation, the single cross rod reduced the most primary rod stress (−48%). Interbody cages and supplementary rods reduced the primary rod stress in a comparable way. Primary rod stress with 2 delta rods and double cross rods were comparable, which were marginally lower than those with conventional supplementary rods. Adding single cross rod was comparable to adding 2 conventional accessory rods in rod stress reduction in flexion. Under lateral bending, delta rods reduced most rod stress whereas under axial rotation, cross rods reduced most rod stress. This study suggested that both delta rods and cross rods reduce more primary rod stress than conventional accessory rods do.