bluuebunny/crossref_metadata_2025 huggingface dataset:
An Analytical Model for Beam Flexure Modules Based on the Timoshenko Beam Theory
Authors: Kahrobaiyan M. H. , Zanaty M. , Henein S.
Published: November 2017

Short beams are the key building blocks in many compliant mechanisms. Hence, deriving a simple yet accurate model of their elastokinematics is an important issue. Since the Euler-Bernoulli beam theory fails to accurately model these beams, we use the Timoshenko beam theory to derive our new analytical framework in order to model the elastokinematics of short beams under axial loads. We provide exact closed-form solutions for the governing equations of a cantilever beam under axial load modeled by the Timoshenko beam theory. We apply the Taylor series expansions to our exact solutions in order to capture the first and second order effects of axial load on stiffness and axial shortening. We show that our model for beam flexures approaches the model based on the Euler-Bernoulli beam theory when the slenderness ratio of the beams increases. We employ our model to derive the stiffness matrix and axial shortening of a beam with an intermediate rigid part, a common element in the compliant mechanisms with localized compliance. We derive the lateral and axial stiffness of a parallelogram flexure mechanism with localized compliance and compare them to those derived by the Euler-Bernoulli beam theory. Our results show that the Euler-Bernoulli beam theory predicts higher stiffness. In addition, we show that decrease in slenderness ratio of beams leads to more deviation from the model based on the Euler-Bernoulli beam theory.
Prediction Methodology for Traction Drive Characteristics of Half-Toroidal Variator System
Authors: Saito Toshihiro , Tamoto Yoshitaka , Inoue Eiji
Published: November 2017

The traction characteristics of a half-toroidal variator system were quantitatively identified. The rheological characteristics of the traction fluid dependent on applied pressure, slip rate, and traction surface temperature were identified from experimental data and finite element analysis using a four-roller machine. Half-toroidal variator system operation should take into account a safety factor, so the variator M versus slip characteristic was clarified by combining a half-toroidal variator model with the identified traction fluid characteristics. This method enabled to quantify the variator M-slip characteristic and power transmission efficiency of a half-toroidal variator in advance, and also enabled visualization of the spinning behavior due to the traction surface frictional force.
Design Under Uncertainty for a Piezoelectric Energy Harvester to Power a Tire Pressure Monitoring System
Authors: Toghi Eshghi Amin , Lee Soobum , Kim Young-Cheol
Published: November 2017

In this paper we perform reliability analysis for a piezoelectric energy harvester to power the tire pressure monitoring sensor (TPMS) under various uncertainty. Reliability based design optimization (RBDO) is applied to improve the performance of the system. Wasted vibrational energy in a vehicle’s rotating tire can be exploited to enable a self-powered TPMS. Piezoelectric type energy harvesters (EHs) are frequently used to collect vibrational energy and power such devices. While exposed to a high impact loading condition in a tire, the harvester experiences increasing strains which is under a higher risk of mechanical failure. Therefore, there is a need for a design to enhance the harvester’s fatigue life as well as maintaining the required power generation. Multiple design optimization studies found to consider the design update by traditional deterministic design optimization (DDO) which does not show reliable performance as it is unable to account for various uncertainty factors including manufacturing tolerances, environmental effects, and material properties. In this study, we consider uncertainty issue by using reliability-based design optimization under presence of various source of uncertainties. The RBDO problem is defined to satisfy power requirement and durability concerns as the constraints while considering design limitations such as compactness and weight. The time varying response of the EH such as generated power, dynamic strain, and stresses are measured by a transient analysis. Sequential Quadratic Programming (SQP) algorithm is used for both DDO and RBDO, and the design results are compared. The RBDO results demonstrate that the reliability of EH is increased by 26% with scarifying the objective function for 2.5% compared to DDO.
On Mode Coupling Analysis and Stability Regions to Energy Harvesting in a Two-Degrees-of-Freedom Portal Frame Platform
Authors: Rocha Rodrigo T. , Balthazar Jose M. , Tusset Angelo M. , Piccirillo Vinicius , Janzen Frederic C. , Felix Jorge L. P.
Published: November 2017

This work aims to study the modal coupling of a nonlinear two-degrees-of-freedom portal frame platform and a numerical analysis of the system with a nonlinear piezoelectric (PZT) material coupled to one of its columns, both externally base-excited. The nonlinear platform possesses two-to-one internal resonance between its two vibration modes and presenting the saturation phenomenon. The nonlinearities of the piezoelectric material are considered by a nonlinear mathematical relation. Here, it is considered an electro-dynamical shaker with harmonic output. The employed methodology to carry out the analysis of this work was: the application of the method of multiple scales to find the best configuration of the parameters, and to find some kind of phenomena due to the two-to-one internal resonance; several numerical simulations were carried out to optimize the energy harvesting through parametrical variations, bifurcation diagrams, stability diagrams. It will be analyzed: the influence of the nonlinearity of the piezoelectric material and of the electro-dynamical shaker on the energy harvesting. Results showed great influence of the nonlinearity of the material and using the electro-dynamical device. It was possible to gain considerably in energy harvesting and stability of the system.
Integrating 3D Stress Analysis With Flexible Multibody Dynamics Simulation
Authors: Bauchau Olivier A. , Han Shilei
Published: November 2017

This paper presents an approach toward the integration of 3D stress computation with the tools used for the simulation of flexible multibody dynamics. Due to the low accuracy of the floating frame of reference approach, the the multibody dynamics community has turned its attention to comprehensive analysis tools based on beam theory. These tools evaluate sectional stress resultants, not 3D stress fields. The proposed approach decomposes the 3D problem into two simpler problems: a linear 2D analysis of the cross-section of the beam and a nonlinear, 1D of the beam. This procedure is described in details. For static problems, the proposed approach provides exact solutions of three-dimensional elasticity for uniform beams of arbitrary geometric configuration and made of anisotropic composite materials. While this strategy has been applied to dynamic problems, little attention has been devoted to inertial effects. This paper assesses the range of validity of the proposed beam theory when applied to dynamics problems. When beams are subjected to large axial forces, the induced axial stress components become inclined, generating a net torque that opposes further rotation of the section and leading to an increased effective torsional stiffness. This behavior, referred to as the Wagner or trapeze effect, cannot be captured by beam formulations that assume strain components to remain small, although arbitrarily large motions are taken into account properly. A formulation of beam theory that includes higher-order strain effects in an approximate manner is developed and numerical examples are presented. The “Saint-Venant problem” refers to a three-dimensional beam loaded at its end sections only. The “Almansi-Michell problem” refers to a three-dimensional beam loaded by distributed body forces, lateral surface tractions, and forces and moments at its end sections. Numerical examples of beams subjected to distributed loads will be presented and compared with 3D finite element solutions.
Velocity/Force Capacities of a Six-Legged Walking Machine
Authors: Tian Yuan , Gao Feng , Liu Jimu
Published: November 2017

Six-legged robots are reliable locomotive machines with actuation redundancy. This paper analyzes the force and velocity capacities of a six-legged high-payload robot geometrically and numerically. The full-body Jacobian between the body platform and the actuation is first of all computed. A geometric computation approach is then proposed to obtain the robot velocity/force polytopes in the platform operational space. System physical constraints of joint torques and velocities are taken into account so that the task space capacities could be quantitatively given. Besides, several capacity indices are also investigated, including the maximum velocity/force magnitude, the maximum velocity/force along a given direction and the maximum isotropic velocity/force. At last, the robot capacities are numerically analyzed with different supporting legs. The results verify high payload capacity of the robot and clarify the influence of different gait parameters on the task space performance. Our method is proposed in a general and convenient framework, and therefore it is beneficial for the quantitative performance evaluation of any multi-legged walking machine with actuation redundancy.
Dynamic Optimization of Pointing Trajectories Exploiting the Redundancy of Parallel Wrists
Authors: Corinaldi David , Callegari Massimo , Palpacelli Matteo-Claudio , Palmieri Giacomo , Carbonari Luca
Published: November 2017

In this paper the functional redundancy of a spherical parallel manipulator performing a pointing task is exploited to optimize its posture upon minimizing dynamic index. A general method to derive the inertia matrix reduced to the mobile platform via screw theory is presented. This matrix encases geometrical and inertial information of all the bodies and it allows a simple computation of dynamic indices due to its feature of being dependent only on the pose of the robot. The indices are used to compute the objective function of the optimization problem, while the orientation of the pointing task constitutes the constraint equations. The posture-optimization is used as a redundancy-resolution and it is extended to any pointing direction. Optimal postural maps are obtained and then used to drive the optimal planning of pointing trajectories by using Bézier curves. To this aim, a higher level optimization problem than previous one is solved and inverse dynamic simulations are conducted to verify the results.
On Offer Shai’s Contribution to Mechanical Engineering and Design
Authors: Reich Yoram , Hahn Elad , Slavutin Michael
Published: November 2017

This paper presents the contribution of Offer Shai to mechanical engineering and design. Over a period of three decades Shai has created an impressive research program that is founded on solid mathematical grounds — combinatorial representations of systems. On this foundation he made contributions that ranged from inventing new concepts in mechanics (e.g., face force), new ways to characterize systems (e.g., singularity positions), new ways to create building blocks to model discrete systems (e.g., Assur graphs and their synthesis), and new methods in design (e.g., infused design). This paper summarizes some of these contributions in an attempt to describe the breadth and depth and attract researchers to continue develop his ideas.
Effects of Technology Assisted Flat Learning Environment for a Design Project at a Historically Black University
Authors: Ramachandran Madhumitha , Siddique Zahed , Akasheh Firas , Kremer Gül E. Okudan
Published: November 2017

Teaching to Learn (TeatoL) is a flat learning environment where peer-to-peer information exchange has been demonstrated to bridge student learning gaps. Within TeatoL, we integrate and expand peer-to-peer knowledge exchange facilitated by technology, in order to enhance the learning of engineering graduates, using an open-ended authentic life problem in design for manufacturing. One of the main objectives for developing TeatoL was to improve the interest and efficacy of underrepresented minority (URM) students in online engineering courses. In this paper, we present our TeatoL implementation at Tuskegee University (TU), to assess the effectiveness of TeatoL in improving student learning and in enhancing ill-structured problem solving skills of URM students. The participants in the learning environment were given an open design problem related to casting process. A short lecture about 35 minutes (Phase 0) was given and then each student team created and uploaded an instructional material (video) on their approach for solving the open-ended problem using computers and mobile phones (Phase I). The students then critically evaluated and posted feedbacks on these peer videos (Phase II). The final step of the process involved students writing a short report on their modified problem solving process and then applied the process to the same open-ended problem (Phase III). The students used comments from peers and information from other videos to modify and improve their approaches. Student learning in all three phases (Phase I through III) was assessed to understand the effects of different modes of learning in TeatoL. Paired t-test, regression and correlation analysis were used to determine the learning gains and how learning happens in a flat learning environment. Paired t-test analysis showed that there were significant learning gains from peer information exchange in TeatoL. Regression and Correlation analysis suggests that number of in-depth comments exchanged during Phase II depends on the initial level of knowledge; and learning gains of students depend on the meaningful comments provided by their peers. The results suggest that, in an online environment, peer-to-peer information exchange in the form of feedback can be particularly useful to attract, retain and train URM students as well as academically underprepared students.
Piezoelectric T-Matrix Development and Multiple Scattering Analysis of Electroacoustic Wave Propagation in Thin Plates
Authors: Darabi Amir , Leamy Michael
Published: November 2017

Harvesting of acoustoelastic wave energy in thin plates and other structures is a promising new research direction for scavenging energy to power small sensors and devices. In particular, metamaterial-inspired harvesting concepts have shown strong potential for enhancing harvesting of acoustoelastic wave energy. In support of continued development of these metamaterial-based concepts, this paper presents a fully-coupled T-matrix formulation for assessing scattering of incident wave energy from a piezoelectric patch attached to a thin plate. The T-matrix serves as an input-output relationship between incident and reflected waves, and is developed herein for a piezoelectric patch connected to an external circuit. The utility of the T-matrix is evident in problems with multiple piezoelectric harvesters, where it can be used with other T-matrices (such as those previously formulated for rigid, void, and elastic inclusions) in a multiple scattering context. This has the potential for many uses in predicting the dynamic response of smart and active structures, but may be particularly useful in accurately assessing metamaterial-based energy harvesting enhancement strategies. Following development of the requisite T-matrix, harvesting in an example Gradient-Index (GRIN) metamaterial structure is predicted using the multiple scattering approach.
Knee Contact Characteristics During Drop Landing Exercise
Authors: Caruntu Dumitru I. , Moreno Ricardo
Published: November 2017

This work investigates the human leg joint contact characteristics during a drop-landing exercise. The contact characteristics consist of tibio-femoral contact forces and contact point, and hip contact forces. An inverse dynamics 2-D model of human leg is used on this ballistic task in order to simplify computation. Experimental data used show a maximum of 100 degrees of flexion angle and ground reaction forces up to 4 times the body weight. All contact forces show a pattern in which they reach large magnitudes at the beginning of landing, decreasing as the subject end the exercise with a standing position.
A Rapid Automatic Life Cycle Assessment Tool for Eco-Design
Authors: Zhu Yongxian , Zhao Fu
Published: November 2017

Increasing concerns about global warming, resource depletion, and ecosystem degradation are pushing manufacturing enterprises to consider environmental impacts of the products they make. Tools such as Life Cycle Assessment (LCA) has been developed to quantify environmental performance of a product, yet the implementation of LCA requires a significant amount of time/resources and its potential in assisting eco-design has been limited. Research has been done to conduct automatic LCA using the simplified database for electronics or to investigate the environmental impact of electricity consumption in a manufacturing process. However, a comprehensive and automated approach is in need to perform LCA analysis for a product considering all related materials and manufacturing processes. In this research, a framework for automating LCA analysis for eco-friendly product design has been developed and implemented with a computer program. A case study has been conducted using the proposed automatic LCA tool to perform life cycle analysis in the design process. The result of the tool can, with minimal time required, provide detailed distribution of life cycle impact indicators among direct inputs and assist in making design decisions to reduce the environmental footprints.
Investigation of Noise Features of Planetary Gear Trains Based on Human Aural Characteristic
Authors: Nakagawa Masao , Nishida Dai , Sah Deepak , Hirogaki Toshiki , Aoyama Eiichi
Published: November 2017

Planetary gear trains (PGTs) are widely used in various machines owing to their many advantages. However, they suffer from problems of noise and vibration due to the structural complexity and giving rise to substantial noise, vibration, and harshness with respect to both structures and human users. In this report, the sound level from PGTs is measured in an anechoic chamber based on human aural characteristic, and basic features of sound are investigated. Gear noise is generated by the vibration force due to varying gear tooth stiffness and the vibration force due to tooth surface error, or transmission error (TE). Dynamic TE is considered to be increased because of internal and external meshing. The vibration force due to tooth surface error can be ignored owing to almost perfect tooth surface. A vibration force due to varying tooth stiffness could be a major factor.
Value-Driven Design Using Discipline-Based Decomposition for a Family of Front-Loading Washing Machines
Authors: Jung Sangjin , Simpson Timothy W. , Bloebaum Christina
Published: November 2017

In order to determine target market and price, and design products/components for a family of front-loading washing machines, the coordination for decision-making from the corporate level down to the product and ultimately component levels is required. However, existing design research for many products focuses on analyzing single or multiple disciplines, even though optimizing local performance does not guarantee minimizing total cost at the product line level or maximizing value at the company level. In this work, we apply a multi-level value-driven design (VDD) approach to optimize a family of front-loading washing machines using a discipline-based decomposition. The VDD solutions obtained using discipline-based decomposition (DD) are compared with those obtained using product-based decomposition (PD). Consequently, the multi-level VDD approach based on DD for the washer family provides better performance for attributes than PD, but we observed that DD for the washer family does not guarantee maximizing the value function compared to PD because of the larger numbers of subsystems and consistency-related variables. Ongoing and future work to address this problem are discussed.
The Inverted Decoupling Based Fractional Order Two-Input-Two-Output IMC Controller
Authors: Li Dazi , He Xingyu
Published: November 2017

Many processes in the industry can be modeled as fractional order, research on the fractional order become more and more popular. Usually, controllers such as fractional order PID (FOPID) or fractional active disturbance rejection control (FADRC) are used to control single-input-single-output (SISO) fractional order system. However, when it comes to fractional order two-input-two-output (TITO) processes, few research focus on this. In this paper, a new design method for fractional order control based on multivariable non-internal model control with inverted decoupling is proposed to handle non-integer order two-input-two-output system. The controller proposed in this paper just has two parameters to tune compared with the five parameters of the FOPID controller, and the controller structure can be achieved by internal model control (IMC) method which means it is easy to implement. The parameters tuning method used in this paper is based on frequency domain strategy. Compared with integer order situation, fractional order method is more complex, because the calculation of the frequency domain characteristics is difficult. The controller proposed in this paper is robust to process gain variations, what’s more, it provides ideal performance for both set point-tracking and disturbance rejection. Numerical results are given to show the performance of the proposed controller.
Optimal Design of Stretchable Electronics With the Consideration of Response Variability
Authors: Hwang Sungkun , Choi Seung-Kyum
Published: November 2017

Strain gauges based on the micro-strip patch antenna have been increasingly employed in structural health monitoring. However, the lower bandwidth, influenced by the antenna’s geometric properties, limits efficiency of the antenna when major strain, creating drastic variation of the resonant frequency, is applied. The performance of the antenna cannot be guaranteed without also considering the substrate’s varying thickness, caused by manual fabrication and printing procedure. However, all such considerations lead to an increase of multivariate design variables, that in turn, increase uncertainty and computational costs. Thus, the proposed research develops a framework that accurately models the geometric variables of the antenna and efficiently reduces the multivariate dimensions that draw uncertainty preventing accurate system reliability estimation. In the proposed framework, a dimension reduction method is thoroughly conducted by utilizing a critical decision criterion depending on the degree of correlation. Specifically, artificial neural network and probabilistic neural network are employed to correctly estimate the variability of complex system responses. Furthermore, an optimal design of the stretchable patch antenna is developed. This design will allow frequency shifts under tensile strain and still remain within reliable frequency ranges. The proposed approach is beneficial to the process of capturing and managing antenna design variables. The presented example clearly demonstrates the advantage of the obtained optimal design of the stretchable patch antenna compared to an ultra-wideband radar system that often requires complicated design processes and high computational costs.
UV-Activated Frequency Control of Beams and Plates Based on Isogeometric Analysis
Authors: Guo Yujie , Tzou Hornsen
Published: November 2017

A new LaSMP smart material exhibits shape memory behaviors and stiffness variation via UV light exposures. This dynamic stiffness provides a new noncontact actuation mechanism for engineering structures. Isogeometric analysis utilizes high order and high continuity NURBS as basis functions which naturally fulfills C1-continuity requirement of Euler-Bernoulli beam and Kirchhoff plate theories. The UV light-activated frequency control of LaSMP laminated beam and plate structures based on the isogeometric analysis is presented in this study. The accuracy and efficiency of the proposed isogeometric approach are demonstrated via several numerical examples in frequency control. The results show that, with LaSMPs, broadband frequency control of beam and plate structures can be realized. Furthermore, the length of LaSMP patches on beams is varied, which further broadens its frequency variation ranges. Studies suggest that 1) the newly developed IGA is an effective numerical tool and 2) the maximum frequency change ratio of beam and plate structures respectively reach 24.30% and 6.37%, which demonstrates the feasibility of LaSMPs induced vibration control of structures.
Concentric Helical Axial Spring Tunable Stiffness Mechanism: Analytical Modeling, Design Optimization and Experimental Validation
Authors: Qaiser Zeeshan , Johnson Shane , Kang Liping
Published: November 2017

The human foot modulates its stiffness in different anatomical regions in order to attain greater efficiency and performance. The purpose of this study is to develop an adaptable robotic foot by biomimicking the human foot’s arch, horizontal tie and its ability of varying its stiffness. In this research we describe the design, modeling, development and optimization of the robotic foot with a novel Tunable Stiffness Mechanism (TSM) which acts as a horizontal tie. The TSM is made up of two concentric helical springs and the tunable stiffness feature is obtained by changing the parallel/series configuration of these springs. A flexible fiberglass composite arch is selected, and Multiobjective Design Optimization (MDO) is used to maximize the stiffness range and effectiveness of the system. Analytical modeling results closely match the experimental validation of both the tunable axial stiffness behavior of the TSM and tunable stiffness foot.
Optimal Design and Robustness Assessment of Product Family Considering Quantity Discounts in Supply Chain
Authors: Nomaguchi Yutaka , Osaki Daiki , Fujita Kikuo
Published: November 2017

Product family design generally aims at overhead reduction due to component commonality meeting various customer needs. Quantity discount is one of the most crucial factors to consider cost reduction effects. However, it also contains the risk of drastic profit decrease when a demand or supply capacity unexpectedly changes. This research aims at proposing an optimal design method of product family with assessment of robustness of expected profit. First, this paper discusses the structure of the optimal design problem of product family considering quantity discount in supply chain. The modeling of quantity discount faces a problem of discontinuous of design spaces. The discontinuity of a design space makes optimization more difficult. This research proposes a method to solve it with reasonable calculation cost by utilizing branch and bound and linear programming. A case study of designing a product family of drip coffee maker demonstrates the application of the proposed method in order to verify it.
Nonlinear Numerical Investigation Around Instability Point of the Flexible Rotor Supported by the Journal Bearing
Authors: Ito Mugen , Inoue Tsuyoshi
Published: November 2017

Rotating machinery supported by the journal bearing may be subject to instability. This instability is classified as the Hopf bifurcation. Either a sub-critical bifurcation or super-critical bifurcation appears depending on the parameters of rotor systems. Conventionally, an infinitely short journal bearing model was used for the investigation of this bifurcation. In this paper, the force transmitted by the oil film of the journal bearing is represented by the finite length model. Nonlinear numerical simulation is performed at around instability point of the flexible rotor supported by the journal bearing. The bifurcation characteristic and the change of bifurcation type are investigated when the ratio L / D, which is the ratio of bearing length L to the bearing diameter D, increases.
Comparison of Fully Parameterized and Gradient Deficient Elements in the Absolute Nodal Coordinate Formulation
Authors: Gerstmayr Johannes , Gruber Peter , Humer Alexander
Published: November 2017

The aim of the present paper is to evaluate six particular beam finite elements based on the absolute nodal coordinate formulation (ANCF). Specifically, accuracy, computational efficiency and numerical stability are compared for those beam finite elements. The finite elements under consideration are planar as well as spatial beams, which are formulated both for the Bernoulli-Euler case as well as for shear and cross-section deformation. While all of the investigated elements have been exposed to specific numerical tests already before, a comparative test has not been performed in the past. The numerical examples cover large deformation static and dynamic problems, which represent typical applications of such beam elements. Finally, the dynamic test problems show that the thin spatial beam formulation, which includes a rotational parameter, leads to well-known numerical instabilities.
Connecting the Real-World and the Virtual World Through Dynamic Environment Rendering
Authors: Lesniak Kevin , Tucker Conrad S.
Published: November 2017

Immersive Virtual Reality (VR) systems such as the Oculus Rift or HTC Vive provide a sense of “presence” that is not available in traditional voice or video based communication methods. Without the sense of “presence” in the environment, a designer’s interpretation of the environment or design in question may be ill informed or skewed, based on the communication medium. The authors of this paper present a method to dynamically recreate a real-world environment in a virtual environment and provide an interface for physically-present individuals and geographically dispersed team members to collaborate. The method allows multiple remote users to naturally and immersively view a realistic representation of a dynamic real-world location in real time. This process incorporates consumer RGB-D sensors and VR systems into a distributed, multi-user virtual environment that has the ability to render large visual data in real-time. A case study using commodity RGB-D sensors, computing hardware, and standard TCP internet connections is presented to demonstrate the viability of the proposed method.
Understanding Effects of Analogical Distance on Performance of Ideation: Key Observations and Findings
Authors: Venkataraman Srinivasan , Song Binyang , Luo Jianxi , Subburaj Karupppasamy , Rajesh Elara Mohan , Blessing Lucienne , Wood Kristin
Published: November 2017

The effect of analogical distance between design stimuli and design problem on novelty and quality of generated concepts is investigated in this research. Data from a design project involving 105 student designers, divided into 21 teams and individually generating 226 concepts of spherical rolling robots, is collected. From this data, 138 concepts generated with patents as stimuli and the patents used as stimuli are analyzed. Analogical distance of a patent is measured in terms of the knowledge distance of the technology classes constituting this patent from the technology classes constituting the design problem domain of spherical rolling robots. The key findings are: (a) technology classes in closer than farther distance from the design problem are used more frequently to generate concepts, (b) as analogical distance increases the novelty of concepts increases, and (c) as analogical distance decreases the quality of concepts increases. These observations have implications on choosing stimuli to generate concepts of desired novelty and quality.
Analytical Treatment for Bistable Nonlinearly Coupled Oscillators
Authors: AL-Shudeifat Mohammad A. , Saeed Adnan S.
Published: November 2017

Here, we introduce an analytical approximation to the exact solution of a bistable nonlinearly coupled oscillators (NLC-LOs) to study the internal resonance at the nonlinear normal modes (NNMs). The considered system is composed of two symmetrical linear oscillators coupled by a bistable nonlinear coupling restoring force. The coupling restoring force includes negative and nonnegative linear and nonlinear stiffness components. The introduced approximate analytical solution for the considered bistable NLC-LOs system is mainly proposed for the cases of which the exact frequency and the exact solution are neither available nor valid. The proposed solution depends on the application of the local equivalent linear stiffness method (LELSM) to linearize the nonlinear coupling force according to the non-linear frequency content in the original system. Accordingly, the bistable nonlinear coupling force in the NLC-LOs is replaced by an equivalent periodic forcing function of which the frequency is equal to that of the original NLC-LOs system. Therefore, the original NLC-LOs system is decoupled into two forced single degree-of-freedom subsystems where the analytical solution can be directly obtained. This obtained analytical solution is found to be highly accurate approximation for the exact solution, especially at internal resonances that occur on some NNMs of the system.
Power Loss Investigation in an Internal Combustion Engine Piston Equipped With a Nonlinear Energy Absorber
Authors: Dolatabadi N. , Theodossiades S. , Rothberg S. J.
Published: November 2017

The piston impacts against the cylinder liner are the most significant sources of mechanical noise in internal combustion engines. Conventionally, the severity of impacts is reduced through the modification of physical and geometrical characteristics of components in the piston assembly. These methods effectively reduce power losses at certain engine operating conditions. Moreover, the conditions leading to the reduction in power losses inversely increase the engine noise due to piston impacts. An alternative control method that is robust to fluctuations in engine operating conditions is anticipated to improve the engine’s NVH performance whilst exacerbation in power loss remains within the limits of the conventional methods. The concept of Targeted Energy Transfer (TET) through the use of Nonlinear Energy Sinks (NES) has not been applied yet in automotive powertrains. Numerical studies have shown a potential in reducing the severity of impact dynamics by controlling piston’s secondary motion. The power loss of a piston equipped with a nonlinear energy sink is investigated in this study.
The Spatial and Temporal Harmonic Balance Method for Obtaining Periodic Responses of a Nonlinear Partial Differential Equation With a Linear Complex Boundary Condition
Authors: Wang Xuefeng , Zhu Weidong
Published: November 2017

The spatial and temporal harmonic balance (STHB) method is used to solve the periodic solution for a nonlinear partial differential equation (PDE) demonstrated by a nonlinear string equation with a linear complex boundary condition, and stablity analysis is conducted for the periodic solutions using Hill’s method. In order to avoid the integration procedure for discretizing the PDE to obtain the ordinary differential equations (ODEs), spatial and temporal harmonic balance procedures are conducted simultaneously, which can be efficiently achieved by the discrete sine transform and the fast Fourier transform. An additional coordinate associated with the generalized coordinates of the trial functions for the spatial discretization is introduced to make the solution satisfy all boundary conditions, and a relationship of the additional coordinate and the generalized coordinates is developed and used in the STHB method so that the test functions can be the same to the trial functions. Jacobian matrix of the harmonic balanced residual is obtained analytically, which can be used in Newton method for solving the periodic response. The STHB method and Jacobian matrix make the calculation of the periodic solution for the nonlinear string with a linear spring boundary condition efficient and easy to be implemented by computer programs. The relationship between the Jacobian matrix and the system matrix of the linearized ODEs are developed, so that one can directly obtain the Toeplitz form of the system matrix, and Hill’s method can be used to analyze the stability with the eigenvalues of the Toeplitz-form system matrix without the derivation of the ODEs. The frequency curve of the periodic solutions is obtained and their stability is indicated by the method in this work.
Extending Design Heuristics From Mechanical Engineering to a Biomedical Projects Course
Authors: Lee Jin Woo , Ostrowski Anastasia K. , Daly Shanna R. , Huang-Saad Aileen Y. , Seifert Colleen M.
Published: November 2017

Research in design has led to emergence of instructional tools to support students in generating multiple candidate concepts. Design Heuristics was developed through empirical studies of professional engineers and award-winning products, and have been shown to support student engineers in generating creative and diverse concepts. We hypothesized that they could be beneficial to student designers in biomedical engineering. In this qualitative classroom study, we examined how graduate students in a biomedical engineering design course applied Design Heuristics to generate individual concepts for their design projects. Our analysis showed that students were able to apply Design Heuristics in their biomedical engineering projects, and that the heuristics supported idea generation in a variety of biomedical engineering design contexts.
Comparison of Collective Team and Individual Student Peer Feedback on Design
Authors: Mandala Mahender , Cole Erin , Schunn Christian , Goldberg Mary , Pearlman Jon
Published: November 2017

Over the past decade, web-based peer reviews have been used to supplement instructor feedback on student work. Peer reviews scale well with class size, and have been shown to increase the frequency and quantity of feedback students receive. Recent work in the domain of design has shown that nearly half of the web-based peer reviews included praise and lacked suggestions for improvement of work. Inspired by the studio model of design critique, we examined the effect of collaborative team review generation on feedback characteristics in contrast to that generated by individual reviewers. In an exploratory study, students from a large sophomore-level engineering design class reviewed their peers’ design logbooks. Students in the team review group evaluated their peers’ work collectively and synchronously, generating a single review. Individual reviewers followed the current standard of reviewing work independently. A coding scheme was developed to analyze the feedback. We found that team reviews, when compared to individual reviews, supplied more ideas per review, more design suggestions to consider, and were more critical of their peers’ work. These trends indicate that team reviews can potentially improve the usefulness of feedback generated, and creates a basis for future exploration of this space.
Control of Nonlinear Systems in Normal Form by Complementary Lyapunov Functions
Authors: Zelenak Andy , Fernández Benito , Pryor Mitch
Published: November 2017

If a Lyapunov function is known, a dynamic system can be stabilized. However, the search for a Lyapunov function is often challenging. This paper takes a new approach to avoid such a search; it assumes a basic Control Lyapunov Function [CLF] then seeks to numerically diminish the value of the Lyapunov function. If a singularity arises during calculations with the default CLF, a complementary function is used. The complementary function eliminates a common cause of singularities with the default CLF. While many other algorithms from the literature use switched or time-varying CLF’s, the presented method is unique in that the CLF’s do not require prior calculation and the technique applies globally. The method is proven and demonstrated for SISO systems in normal form and then demonstrated on a higher-order system of a more general type.
Finite Position Synthesis of 5-SS Platform Linkages Including Partially Specified Joint Locations
Authors: Ge Xin , Purwar Anurag , Ge Q. J.
Published: November 2017

A 5-SS platform linkage generates a one-degree-of-freedom motion of a moving platform such that each of five moving points on the platform is constrained on a sphere, or in its degenerated case, on a plane. It has been well established a 5-SS platform linkage can be made to guide though seven positions exactly. This paper investigates the cases when the number of given positions are less than seven that allows for partial specification of locations of the moving points. A recently developed novel algorithm with linear structure in the design equations has been extended for the solution of the problem. The formulation of this expanded motion generation problem unifies the treatment of the input positions and constraints on the moving and fixed joints associated with the 5-SS platform linkage. Numerical examples are provided to show the effectiveness of the unified algorithm.
Design and Analysis of a Shell Mechanism Based Two-Fold Force Controlled Scoliosis Brace
Authors: Nijssen Joep P. A. , Radaelli Giuseppe , Herder Just L. , Kim Charles J. , Ring J. B.
Published: November 2017

In this paper a first iteration of a new scoliosis brace design and correction strategy is presented using compliant shell mechanisms to create both motion and correction. The motion profile of the human spine was found using a segmented motion capture approach. The brace was designed for a case study using a conceptual ellipsoid design approach. The force controlled correction profile was re-invented using a two fold zero and positive stiffness profile. These force generators were built and validated to prove their zero stiffness characteristic. The kinematic part of the brace was detail designed with the correct order of magnitude and validated through their force-deflection characteristic. The end result was a first iteration of a new brace validated and analysed on some critical components which can form the basis for a future biomechanical study.
Evaluating the Discriminatory Value and Reliability of Ideation Metrics for Their Application to Concept Development and Prototyping
Authors: Menold Jessica , Jablokow Kathryn , Simpson Timothy , Seuro Rafael
Published: November 2017

Approximately half of new product development projects fail in the market place. Within the product development process, prototyping represents the largest sunk cost; it also remains the least researched and understood. While researchers have recently started to evaluate the impact of formalized prototyping methods and frameworks on end designs, these studies have typically evaluated the success or failure of these methods using binary metrics, and they often evaluate only the design’s technical feasibility. Intuitively, we know that a product’s success or failure in the marketplace is determined by far more than just the product’s technical quality; and yet, we have no clear way of evaluating the design changes and pivots that occur during concept development and prototyping activities, as an explicit set of rigorous and informative metrics to evaluate ideas after concept selection does not exist. The purpose of the current study was to investigate the discriminatory value and reliability of ideation metrics originally developed for concept generation as metrics to evaluate functional prototypes and related concepts developed throughout prototyping activities. Our investigation revealed that new metrics are needed in order to understand the translation of product characteristics, such as originality, novelty, and quality, from original concept through concept development and prototyping to finalized product.
Norigami Crease Pattern Model Design Based on Surfaces of Revolution
Authors: Romero J. A. , Diago L. A. , Hagiwara I.
Published: November 2017

In this work, we present a strategy to design and construct 3D shape paper models that can be automatically folded and glued using a robotic machine. Here, we use concepts of “kirigami”, that is a combination of folding and cutting paper, and “norigami”, that combines folding with gluing of the paper. A software was developed in order to create crease patterns using a two-dimensional polyline profile and rotating it around an axis by a unit of 2π/N rad (N>2). The gluing areas were modified to permit free allocation and movement. The proposed method is also evaluated and validated to construct several 3D shapes using paper-like materials by hand, or using a special machine developed in our previous researches.
Smart Resonant Gas Sensor and Switch Operating in Air With Metal-Organic Frameworks Coating
Authors: Jaber Nizar R. , Ilyas Saad , Shekhah Osama , Eddaoudi Mohamed , Younis Mohammad I.
Published: November 2017

We report a resonant gas sensor, uniformly coated with a metal-organic framework (MOF), and excited it near the higher order modes for a higher attained sensitivity. Also, switching upon exceeding a threshold value is demonstrated by operating the resonator near the bifurcation point and the dynamic pull-in instabilities. The resonator is based on an electrostatically excited clamped-clamped microbeam. The microbeam is fabricated from a polyimide layer coated from the top with Cr/Au and from the bottom with Cr/Au/Cr layer. The geometry of the resonator is optimized to reduce the effect of squeeze film damping, thereby allowing operation under atmospheric pressure. The electrostatic electrode is designed to enhance the excitation of the second mode of vibration with the minimum power required. Significant frequency shift (kHz) is demonstrated for the first time upon water vapor, acetone, and ethanol exposure due to the MOF functionalization and the higher order modes excitation. Also, the adsorption dynamics and MOF selectivity is investigated by studying the decaying time constants of the response upon gas exposure.
Demystifying the Relationship Between Use-Phase Attributes and Energy Consumption: A Case Study of Personal Computers
Authors: Raihanian Mashhadi Ardeshir , Behdad Sara
Published: November 2017

Understanding the use-phase energy consumption of consumer electronics is of great importance, as it has significant effects on both policy and product designs. Inaccurate estimations of the use phase energy consumption can offset the results of the life cycle assessment and impeach the effectiveness of the energy intervention policies. The use phase energy consumption is governed by the consumers’ usage behavior. However, the relationship between consumers’ attributes and their usage behavior, and energy consumption is not clear. This paper analyzes two data sets, a data set of hard drives’ Self-Monitoring, Analysis and Reporting Technology (S.M.A.R.T) and the Residential Energy Consumption Survey (RECS) to shed light on the relationship between usage behavior and energy consumption. Several supervised and unsupervised machine-learning methods have been used to reveal possible trends in the consumers’ use-phase attributes. The results of the study suggest that various demographic properties and behavioral variables related to computer usage affect the energy consumption profile of households.