bluuebunny/crossref_metadata_2025 huggingface dataset:
Neural Network-Based Fuzzy Reasoning for Conceptual Design Evaluation
Authors: Sun J. , Kalenchuk D. K. , Xue D. , Gu P.
Published: February 2021

This paper presents a neural network-based fuzzy reasoning method for design candidate evaluation and identification to improve design quality and efficiency at the crucial conceptual design stage. The evaluation and identification of design candidates are carried out through the following four steps: (1) acquisition of customer needs and ranking of their importance, (2) establishment of measurable metrics and their relations with customer needs, (3) development of design specifications and initial evaluation of design candidates, and (4) evaluation and identification of design candidates based on design specifications and customer needs. A case study is given to show the effectiveness of the neural network-based fuzzy reasoning method in conceptual design evaluation.
An Exact Method for NC Verification of up to 5-Axis Machining
Authors: Abdel-Malek K. , Seaman Walter , Yeh Harn-Jou
Published: February 2021

The motion of a cutter tool is modeled as a surface undergoing a sweep operation along another geometric entity. A numerically controlled machining verification method is developed based on a formulation for delineating the volume generated by the motion of a cutting tool on the workpiece (stock). Varieties and subvarieties that are subsets of some Eucledian space defined by the zeros of a finite number of analytic functions are computed and are characterized as closed form equations of surface patches of this volume. A topological space describing the swept volume will be built as a stratified manifold with corners. Singularities of the variety are loci of points where the Jacobian of the manifold has lower rank than maximal. It is shown that varieties appearing inside the manifold representing the removed material are due to a lower degree strata of the Jacobian. Some of the varieties are complicated (so as not to confuse with varieties in complex Cn) and will be shown to be reducible because of their parametrization and are addressed. Benefits of this method are evident in its ability to depict the manifold and to compute a value for the volume.
Automated Methods in Computer Aided Design
Authors: Abdel-Malek K. , Zou H.-L. , Wang J.-Y. , Othman S.
Published: February 2021

A numerical variational method is herein introduced for the automatic redesign of mechanical parts subject to a design change. This method is demonstrated to the design of mechanical parts in the context of concurrent engineering of 3D parts. Relations between dimensions in a mechanical part as dictated by a designer are modeled using mechanisms and their kinematic relations. Variational cut-joint constraints are introduced, kinematic joints in the formulation are combined, and a Jacobian is determined. Constraint violations are then compensated to compute an assembled mechanism, hence redesigning the part. It is shown that this formulation is broadly applicable to 2D and 3D models. The method and algorithm are illustrated through examples.
Methodology and Implementation of Dynamic Design Advisor (DDA) in a Feature-Based System
Authors: Bardhan Tridip K. , Rajan Venkat N. , Masud Abu S. M.
Published: February 2021

Designing right the first time decreases cost significantly. If requirements of downstream activities could be considered during conceptual design, fewer changes would be required later. A design advisory system can provide enough information to the designer to achieve this goal of designing right at the conceptual stage. A systematic methodology for design advising in a feature-based design environment is developed to identify problems at the design stage, and provide the designer the opportunity to correct them. Five pre-conditions are also identified for this methodology. During the development of the part geometry, a multi-digit code is added to every feature. Based on the code, all applicable design rules are checked as constraints and in case of constraint violation, suggestions are generated and presented to the designer. During the design process, the designer can check a design rating, generated from the extent to which the constraints are satisfied. An example session is also presented to illustrate the ten steps of this method. To validate the developed methodology, a DDA system for pipeline design is developed in an actual industrial application. Effectiveness of the DDA methodology is analyzed by comparing the designers’ performance using the feature-based DDA system with performance using a regular feature based system. The performance measures used are: the number of errors in a design and the time taken to complete the design. Statistical results indicate that designers perform better with the DDA system in terms of fewer errors and less time to design.
Structural Abstraction in Snap-Fit Analysis
Authors: Suri Gaurav , Luscher Anthony F.
Published: February 2021

Snap-fit design has always been more of an art rather than a pure engineering science. Research in this area focuses on generating finite element models for predicting the performance of snap-fit features. Such research typically uses fixed end conditions at the base of the snap-fit feature. Often this is an unrealistic assumption, because snap-fits are usually molded on plastic parts with significant flexibility. The performance of snap-fits can be significantly influenced by this additional flexibility.

To predict the performance of snap-fits in complex plastic parts, it has often been necessary to analyze the entire part, which can be a costly and time consuming process. There is no general methodology in the open literature to incorporate base-part flexibility into the design of snap-fit features. Existing work in this area such as Q-Factor charts, is inaccurate and specific to certain base-part and snap-fit topologies.

This paper proposes a new methodology called structural abstraction for incorporating base-part flexibility into feature models. This methodology abstracts base-parts as spring elements with various stiffnesses. The theory behind this approach and the relevant relationships are developed and the approach is validated using several test cases. Independence of the approach to both base-part and snap-fit topologies is established and shown to be a major advantage of this technique. Use of this methodology will improve snap-fit analysis and give a more accurate estimation of retention strength. It is shown that in certain cases the improvement in accuracy can be as high as 70 percent or more.
Overlap Detection Using Minkowski Sum in Two-Dimensional Layout
Authors: Yu Chan , Manoochehri Souran
Published: February 2021

In optimal layout problems, which are often demanded by many industries, it is desired to have new computer-based approaches that are fast and effective. To determine the overall speed of layout procedure, one has to consider not only the search algorithm but also the performance of overlap detection algorithm. In this paper, a new methodology of detecting an overlap in two-dimensional layout problem is presented. This method introduces the concept of Minkowski sum, which is defined as an algebraic sum of two point sets, to the overlap detection. Using mathematical relations, the algorithm can rapidly detect if two convex objects are overlapping, fully contained or separated. Fast detection of overlaps eventually allows user to accelerate the overall speed of layout algorithms. In addition, to obtain the robustness of this method it is being extended to the cases involving irregular-shaped non-convex objects.
Configuration Design Optimization Method
Authors: Grignon Pierre M. , Fadel Georges M.
Published: February 2021

This work presents a method (CDOM) for optimizing multiple system level assembly characteristics of complex mechanical assemblies by placement of their components. It addresses any component shape (including non-convex, hollow, sharp edges) connected together by functional constraints. This method finds multiple solutions to the Engineering Configuration Design Problem (ECDP) and proposes a simple cooperation scheme with the engineer using a Genetic Algorithm working on population of sets instead of population of individual points. In this paper four areas are addressed:

• defining the assembly components and their relations (ECDP)

• defining the Configuration Design Optimization Method (CDOM)

• propose two strategies to improve the CDOM performance

• show application of the CDOM to one academic and two engineering test cases
Robust Design via Tolerance Analysis in the Conceptual Design Stage
Authors: Parkinson Alan , Chase Kenneth , Rogers Matt
Published: February 2021

Robust design methods are used to develop designs which can tolerate variation. Most methods developed to date are applied during the detailed design phase. Yet the potential for developing robust designs is greatest during the conceptual design stage, where the overall design concept is determined.

This research is part of a larger effort to develop robust design methods for conceptual design. The focus of the research is on developing methods for identifying critical tolerances during concept evaluation. We propose that in many mechanical designs, a 70-30 rule applies: 30% of the tolerances contribute 70% of the variation. This hypothesis is supported by the results from several case studies. We discuss progress in developing methods — in particular the vector loop method — which can be applied during conceptual design to detect critical tolerances. By being aware of these tolerances early in the design process, the designer can either change the design to make the tolerances less critical or make sure the tolerances are appropriately considered as manufacturing process plans are developed.
Robust Design for Improved Vehicle Handling Under a Range of Maneuver Conditions
Authors: Chen Wei , Garimella Raman , Michelena Nestor
Published: February 2021

In this article, a robust design procedure is applied to achieve improved vehicle handling performance as an integral part of simulation-based vehicle design. Recent developments in the field of robust design optimization and the techniques for creating global approximations of design behaviors are applied to improve the computational efficiency of robust vehicle design built upon sophisticated vehicle dynamic simulations. Our approach is applied to the design of a M916A1 6-wheel tractor / M870A2 3-axle semi-trailer. The results illustrate that the proposed procedure is effective for preventing the rollover of ground vehicles as well as for identifying a design that is not only optimal against the worst maneuver condition but is also robust with respect to a range of maneuver inputs. Furthermore, a comparison is made between a statistical approach and a bi-level optimization approach in terms of their effectiveness in solving robust design problems.
Interactive Multiobjective Optimization Design Strategy for Decision Based Design
Authors: Tappeta Ravindra V. , Renaud John E.
Published: February 2021

This research focuses on multi-objective system design and optimization. The primary goal is to develop and test a mathematically rigorous and efficient interactive multi-objective optimization algorithm that takes into account the Decision Maker’s (DM’s) preferences during the design process. An Interactive Multi-Objective Optimization Procedure (IMOOP) developed in [12] has been modified in this research to include the DM’s local preference functions in an Iterative Decision Making Strategy (IDMS). This enhanced multiobjective optimization procedure called the interactive MultiObjective Optimization Design Strategy (iMOODS) provides the DM with a formal means for efficient design exploration around a given Pareto point. The use of local preference functions allows the original algorithm [12] to be modified such that the second order Pareto surface approximation is more accurate in the preferred region of the Pareto surface. The iMOODS has been successfully applied to two test problems. The first problem consists of a set of simple analytical expressions for the objectives and constraints. The second problem is the design and sizing of a high-performance and low-cost ten bar structure that has multiple objectives. The results indicate that the class functions are effective in capturing the local preferences of the DM. The Pareto designs that reflect the DM’s preferences can be efficiently generated within IDMS.
Fictitious Domain Solution of Frequency Response Problems
Authors: Chellappa Sudarsanam , DeRose Giuseppe C. A. , Diaz Alejandro R.
Published: February 2021

This paper discusses an alternative solution strategy for frequency response problems in elasticity. This strategy uses a meshless method, derived in a periodic domain setting, extended to allow the analysis of arbitrary geometries with the use of a fictitious domain. This solution technique is designed to solve problems with a large number of degrees of freedom and it requires the use of iterative solvers where preconditioning is necessary for reasonable convergence rates. Two dimensional examples illustrating this approach are provided.
Touch Recognition Using a Passive Large Compliance Robotic Finger With Internal Sensors for Planar Applications
Authors: Hong Dennis W. , Cipra Raymond J.
Published: February 2021

In this paper, a touch-sensing device consisting of a passive large compliance robotic finger with internal sensors, and algorithms for using this device for recognition applications are presented. These algorithms include recognition of the two-dimensional projected outline shape and dimensions of an object, and recognition of the three-dimensional convex outline height profiles of an object. The two-dimensional outline of an object is identified by tracing the object’s outer edge with the robotic finger and returning the XY coordinates of selected outline contact points and their tangent line directions. Recognition of the three-dimensional convex outline height profiles of an object is done by observing the change of the robotic finger deflection angle while moving the finger toward the object in contact. The feasibility of the device and the algorithms developed were successfully tested for planar applications by both analytical simulations and by experiments using a simple two-degree-of-freedom inverted joystick attached to the end of a planar manipulator arm. Simplicity, low cost, and easy implementation are some of the major benefits of using the proposed touch-sensing device.
A Fuzzy Adaptive Simplex Search Optimization Algorithm
Authors: Trabia Mohamed B. , Lu Xiao Bin
Published: February 2021

Optimization algorithms usually use fixed parameters that are empirically chosen to reach the minimum for various objective functions. This paper shows how to incorporate fuzzy logic in optimization algorithms to make the search adaptive to various objective functions. This idea is applied to produce a new algorithm for minimization of a function of n variables using an adaptive form of the simplex method. The search starts by generating a simplex with n+1 vertices. The algorithm replaces the point with the highest function value by a new point. This process comprises reflecting the point with the highest function value in addition to expanding or contracting the simplex using fuzzy logic controllers whose inputs incorporate the relative weights of the function values at the simplex points. The efficiency of the algorithm is studied using a set of standard minimization test problems. This algorithm generally results in a faster convergence toward the minimum. The algorithm is also applied successfully to two engineering design problems.
Basic Models for Topology Design Optimization in Crashworthiness Problems
Authors: Soto Ciro A. , Diaz Alejandro R.
Published: February 2021

A study of basic and simple models for topology design optimization in crash events is presented. A 1D collinear and a 2D truss lattice models were implemented and used to solve a set of problems to design the topology of structural members of vehicles under frontal crash. Both design models explore several optimization formulations as well as possible design variables to address the fundamental issues in crashworthiness design, namely, minimization of accelerations while controlling or reducing deformations. Results show the viability of these simple models to solve structural topology optimization problems for crashworthiness.
Applications of Wavelet Based Signature Analysis in Designing for Crashworthiness
Authors: Gearhart Chris
Published: February 2021

We present a statistical method for characterizing the information contained in multiple crash pulses. This method uses a wavelet expansion to give a compact representation of each of the crash pulses analyzed. A probable distribution of the wavelet coefficients representing each pulse is calculated. Bayesian inference is used to determine the most probable subset of wavelet coefficients needed to describe the data sets. This subset forms a signature that is representative of all the crash pulses used for the analysis. For tests we have analyzed the wavelet signatures typically consist of 10 to 20 wavelet coefficients which can be associated with specific subsystems in the vehicle. These signatures can be used as a basis for measuring correlation between pulses. We demonstrate this by comparing signatures taken from two types of sedans and from two types of trucks. Correlation between CAE analysis and test results or between CAE analysis and design objectives are also possible. We present results from one application in which correlation, based on wavelet signatures, is used to move a crash worthiness concept model toward a specified design target.
A Problem Solving Architecture for Virtual Prototyping in Metal to Polymer Composite Redesign
Authors: Zhou Kongyi , Lenz Timothy , Radcliffe Clark , Sticklen Jon
Published: February 2021

Conceptual design is an early but important stage of the design process that greatly affects the quality and cost of the final design. Intelligent tools that embody design rationale about function, structure, material, and manufacturing technology can help designers quickly generate and evaluate configuration ideas. This can help shorten the design cycle and reduce the risk of design failure in later stages. This paper presents a virtual prototyping system for redesigning metal structures out of polymer composites. The system provides a modeling tool to represent the original design based on a domain-specific ontology and a design transformation tool that generates, refines, and evaluates redesign concepts for composites. The discussion in this paper focuses on the system architecture that performs the design transformation problem solving. Important issues in the transformation strategies and control mechanisms are also addressed. An example of the redesign of a portion of an unmanned aerial vehicle is used to illustrate the redesign process throughout.
Generation of Design Data Through Numerical Modeling of a Post and Dome Feature
Authors: Nichols David A. , Luscher Anthony F.
Published: February 2021

This paper focuses on developing improved design equations to estimate the retention strength, insertion force, and insertion strain of a particular snap-fit, the post and dome feature. Finite element methods and multiple regression techniques were used in lieu of beam equations to develop the improved design equations. Sensitivity data is plotted for both the main effects and selected variable interactions. A study of detailed catch geometry was done in order to identify an optimal catch geometry. Typical design parameters were varied in order to develop design equations for users of this feature.

The post and dome feature was selected for analysis because it is a high performance snap-fit that is self-datuming and can take some shear loading in addition to retention. The post and dome provide a higher ratio of retention force to insertion force than traditional cantilever snap-fits, and retention is less dependent on friction.
Design of Optimally Stiff Structures Using Shape Density Function
Authors: Kumar Ashok V. , Wood Aaron
Published: February 2021

Optimization techniques for the design of the shape and topology of structures is presented where the geometry is represented using contours of a piece-wise bilinear shape density function. The relation between the material properties and the density function is studied to understand the influence of this relation on the optimal design obtained. Relations that would yield homogeneous and fully dense optimal designs are sought.
Turbine Disk Forging Process Optimization
Authors: He Beichang , Zhou Youdong , Gambheera Ramesh , Srivatsa Shesh K.
Published: February 2021

This paper addresses one of the important aspects of the turbine disk forging process — the design of die geometry to achieve near-net-shape forging. The problem is formulated as a parametric geometry and high-fidelity analysis based optimization problem. The forging weight is minimized within prescribed processing windows and forging rules including bounds on strain, temperature, strain rate, press capacity, dwell time, sonic coverage, fillet radius, draft angles, etc. A fully automated analysis and optimization system that works in a heterogeneous and networked computing environment is built on the top of three commercial software packages: DEFORM for simulating metal forming process, Unigraphics for defining and manipulating geometry, and iSIGHT for software integration and optimization. The system is applied to the optimization of turbine disks.
System-Level Functional Testing for Scaled Prototypes With Configurational Distortions
Authors: Cho Uichung , Wood Kristin L. , Crawford Richard H.
Published: February 2021

The means to obtain and manage design information is a critical factor that decides the performance of product development processes. Designers use both virtual and physical models to design high quality products. Relatively, virtual models are flexible and require less time and cost, and physical models more accurately reflect physical phenomena.

Correlation between physical models and products is difficult, except for situations in which the Buckingham Π theorem holds. We developed the empirical similarity method for situations not handled by the Π theorem. The empirical similarity method for products composed of a single material has been described previously. In this paper, we extend the empirical similarity method to predict behaviors of products composed of multiple materials. Through the extended method, one can perform system-level functional testing with prototypes.

Numerical and experimental examples are provided for illustration and validation purposes. The examples demonstrate the feasibility of the empirical similarity method to correlate systems with distinct configurations, and clarify expected industrial benefits.
Requirements for Testing Plastic Snap-Fit Features
Authors: Bodmann Douglas R. , Luscher Anthony F.
Published: February 2021

This paper discusses current efforts and evaluates future directions to construct and operate a physical-testing lab for the evaluation of snap-fit features. This testing is necessary for quantifying existing snap-fit features and verifying their numerical simulations. It will serve as an introduction into key issues in mechanical snap-fit feature testing. It reviews key decisions made to minimize error and maximize the ability to test a wide range of snap-fit topologies. A systematic approach to fixturing snap-fit topologies is proposed, dividing them according to basepart geometry and geometric description. Specific machine components are listed and selection criteria are expanded upon.

Sample feature information is presented. The post and dome and annular trap features results are specifically presented. Understanding their testing results aids understanding of issues in precision testing. Finally proposed future efforts for precision contacting and non-contacting alignment and other longer-term methodologies are mentioned.
Finite Element Modeling of a Moving Deformable Barrier for Fuel System Performance Simulations
Authors: Tyan Tau , Cheng James
Published: February 2021

An improved moving deformable barrier (MDB) model was developed for simulation of fuel system performance tests. This MDB model was designed to replace a bullet vehicle model for the vehicle-to-vehicle impact simulations where a bullet vehicle impacts a target vehicle at 50mph. This study included three crash modes, rear-inline, rear-50% offset, and side impact-centerline of fuel filler, required in the fuel system integrity test. The MDB model is composed of a barrier facial, same as the FMVSS (Federal Motor Vehicle Safety Standards) 214 [1] side impact barrier facial, and a movable cart on which the barrier facial is mounted. The main block and bumper block in the barrier facial are modeled by using solid elements while aluminum plates are represented by using shell elements. The movable cart is modeled by using beam elements with four air-bag tires. Two dynamic component tests were adopted to calibrate the barrier facial properties. To assure the model is applicable to all vehicle lines and different test modes, extensive validation was conducted. The full system validation contained a car, a mini-van, a van, and a pick-up truck. Three different test modes were all included in this study. Both accuracy and numerical stability of the model were examined carefully in each simulation. For accuracy, the deformation modes and responses of the MDB were compared to those of the tests. Time steps were monitored in each simulation to investigate the degradation of numerical stability. Through calibration and validation, the MDB model was found to be robust and numerically stable.
Feature-Based Slicing for Layered Manufacturing
Authors: Qian Xiaoping , Dutta Debasish
Published: February 2021

Layered manufacturing (LM) has become an indispensable manufacturing technology for product design and development. Competition pressure demands high quality LM part within an even shorter lead time. This requires an efficient fabrication strategy for LM. In contrast to prevalent LM methods whereby each layer is uniformly deposited with same layer thickness, we are exploring a different approach for LM. That is, fabrication strategies are localized to best meet the design specification of each individual feature in the part. Therefore, slicing, deposition path planning, etc., are done separately for each feature volume to get the best quality for that feature volume. Specifically, in this paper, we present a feature-based slicing method, which localizes the slicing for each individual feature volume. We propose the concept of feature interaction volume and describe how the part volume can be decomposed into refined feature volumes and feature interaction volumes. In refined feature volumes, the fabrication strategies are completely independent of the neighboring volumes. Some examples are presented to validate the feature-based slicing method.
Feature Decomposition for Hexahedral Meshing
Authors: Lu Yong , Gadh Rajit , Tautges Timothy J.
Published: February 2021

This paper presents a feature based volume decomposition approach for Hexahedral Mesh generation. In this approach, feature recognition techniques are introduced to determine decomposition features from a CAD model and the model is decomposed into sub-models, which become meshable or can be meshed by meshing algorithms in a computationally inexpensive manner. The feature recognition methods employed are convexity based and use topology and geometry information, which is generally available in BREP solid modelers. The procedure of feature decomposition is recursive: sub-models are further decomposed until either they are matched with appropriate meshing algorithms or no more decomposition features are detected. The code is designed and programmed for self-adaptation and error-tolerance to achieve high automation with complex geometry. The paper gives testing results for several complicated manufactured parts.
Evaluation and Comparison of Alternative Compliant Over-Running Clutch Designs
Authors: Roach Gregory M. , Howell Larry L.
Published: February 2021

Compliance criteria is used to evaluate the general class of over-running clutches to determine which type is best suited to benefit from compliance. The criteria used in the evaluation include the presence and amount of revolution of revolute joints, the possibility for part count reduction, the presence of springs, possible reduction in weight, and the method of clutch engagement. The ratchet and pawl type of over-running clutch was shown to be the most promising. Within this type of over-running clutch, different designs incorporating bending, tension, and compression loading of the pawls were explored to determine the best method for loading the pawls. The clutches were compared using a ratio of the maximum output torque to over-running torque. It was determined that the clutch incorporating rigid pawls loaded in compression produced the largest ratio of output torque to over-running torque. The maximum output torque for this clutch was measured at 65.6 N-m and the over-running torque was measured at 0.011 N-m yielding a ratio of 5964.
Geometric Features Applied to Composite Surfaces Using Spherical Reparametrization
Authors: Stewart Paul J. , Chen Yifan
Published: February 2021

The Direct Surface Manipulation (DSM) method allows creation and modification of user-specified features on an existing parametric surface. A global surface reparametrization scheme is presented that extends DSM to include features spanning multiple surfaces. This technique globally reparametrizes multiple surfaces onto a two-dimensional space, and the result is used as a global, uniform parametric space to connect the topologically-disconnected surfaces. Features defined on the common parametric space then span multiple surfaces. Spherical projection is presented as an effective projection method to use for the global reparametrization because of its ability to reduce shape distortions for features placed on surfaces with substantial curvature variation.
Dynamic Analysis of Five-Bar Mechanisms With Torsional Springs Using Lagrange’s Equation and Kinematic Coefficients
Authors: Nguyen Philip P. , Cipra Raymond J.
Published: February 2021

This research investigates the dynamic motion of planar closed loop two-degree-of-freedom five-bar mechanisms with torsional springs. An analysis technique is presented which incorporates a combination of the Lagrange’s equation and the method of kinematic coefficients in a manner similar to the power equation to achieve improved efficiency. Using the basic mechanism vector loop, the kinematic coefficients and the point path kinematic coefficients are solved symbolically. This information is then incorporated into Lagrange’s equation to produce a formulation that yields the equations of motion. The analysis technique is then tested using a simple example that validates the hybrid Lagrange formulation. An example of a generic five-bar mechanism with a torsional spring is given to demonstrate the use of the analysis technique. The example illustrates the motion of the linkage and the effect of altering certain mechanism parameters. The study reveals that the dynamic response of certain five-bar mechanisms with torsional springs can be significantly altered through minor design changes.
Fastening Strategies for Large Thin-Walled Enclosures
Authors: Jenkins David M. , Luscher Anthony F. , Suri Gaurav
Published: February 2021

Current attachment strategies for thin walled thermoformed panels use various concepts from screws, rivets, to snap-fits, etc. The most common of these strategies is to use standard metal fasteners such as pop rivets or screws. According to Boothroyd & Dewhurst analysis, separate fasteners do not add functionality to the product and therefore the overall assembly efficiency of the structure is low (Boothroyd and Dewhurst, 1989). Each fastener also adds several manufacturing and assembly steps. For each standard fastener a through hole must be drilled in the panels and the fastener must be inserted. There is also the possibility that the fasteners will not hold the panels tightly against each other resulting in joints with a poor physical appearance and a loss of structural stiffness.

This paper explores different innovative strategies to fasten thin walled thermoformed panels. The rod, ribbon and interlocking concepts use nesting strategies to aid attachment with the addition of a single separate part or allowing the walls themselves to form a joint. Nesting strategies are used to minimize the number of fasteners needed in a joint (Luscher et. al. 1996). A nesting strategy uses locating features to carry load in certain directions which reduces the load on the fasteners. Any reduction in load will lead to a reduction in the number of fasteners needed. The other concept discussed, separate plastic fastener concept, will change attachment from metal fasteners to independent plastic snap-fits. This is a simplified alteration resulting in minor changes to manufacturing and assembly processes.

Equations for attachment strategies with the use of certain concepts will be addressed. Also data from testing on snap-fits in use with a thin walled thermoformed structure will be reported.
A Product Variety Tradeoff Evaluation Method for a Family of Cordless Drill Transmissions
Authors: Conner Carolyn G. , De Kroon Joseph P. , Mistree Farrokh
Published: February 2021

In this paper we present the Product Variety Tradeoff Evaluation Method for assessment of alternative product platforms in product family design. The Product Variety Tradeoff Evaluation Method is an attention-directing tool for evaluating tradeoffs between commonality and individual product performance for product platform alternatives with differing levels of commonality. We apply the Product Variety Tradeoff Evaluation Method to a case study in transmission redesign for a family of cordless drills. The emphasis in this paper is placed on the method rather than on the results, per se.
Optimized STL File Generation From Scattered Data
Authors: Wang Y. Z. , Chen Y. H.
Published: February 2021

In this paper, a novel method is proposed for the prototyping of digitized data by means of rapid prototyping technologies without constructing a CAD model. Firstly, an optimized STL file (the de facto file format for rapid prototyping machines) is constructed directly from digitized part data. In order to reduce storage space and increase computational efficiency for subsequent processes such as slicing, significant data reduction can be achieved at users’ discretion by deleting data points in planar and near planar regions. Points around the ‘blank region’ left by deleted triangles are linked through re-triangulation to form triangular facets obeying STL file rules. To obtain optimized re-triangulation result, a genetic algorithm (GA) is developed and implemented. Finally, experiments on different amount of data reduction over a digitized sample are conducted with satisfactory results.
Minkowski Operators and Features of Voxel Models
Authors: Chandru V. , Manivannan M. , Manohar S.
Published: February 2021

Feature-based design has evolved as a fundamental paradigm for present-day CAD systems. Voxel-based modeling has many advantages over traditional representation schemes but lacks structural information which is lost in voxelization of the objects. In this paper, we propose to augment voxel models with features by a) storing the sequence of modeling operations along with voxel models and b) by defining feature operators. We have implemented these ideas in our prototype system Sirpi as regularised Minkowski operators using simple data structures and algorithms.
Methodology for Designing Low-Vibration Structures for Movable Mechanisms
Authors: Yoshida Shinobu , Kawabe Yoshiko
Published: February 2021

The methodology dealt with here is the way how to use numerical simulation methods corresponding to different design steps. The methods are a budget simulation method for mechanical specification design step, a structural vibration analysis method using a finite element method and an optimization method. The latter two methods are used for the module design and parts design steps. Case studies reviewing the works of authors show the effectiveness of the methodology.
A New Method for Determining the Effects of Structural Flexibility on the Dynamic Behavior of High Speed Mechanisms
Authors: Yuan L. , Rastegar J.
Published: February 2021

A new method for the analysis of the effects of structural flexibility on the dynamic behavior of mechanical systems is presented. The developed method is in most part based on “tracing” the “propagation” of the effects of the high frequency motion requirements on the dynamic response characteristics of machines with structural flexibilities, particularly those with closed-loop kinematic structures. The method considers the “filtering” action of structural elements with flexibility. Such filtering of higher frequency motions is shown to have a predictable effect on the steady state motion of such mechanical system. The main advantage of the developed method is that the effects of such flexibilities can be determined without the need to perform the usual dynamics modeling and computer simulations. The method is shown to be very simple and readily implementable. The method is applied to a four-bar linkage mechanism with a longitudinally flexible coupler link. The obtained results are shown to be highly accurate as compared to those obtained by computer simulation. The application of the method to systematic design of machines with structural flexibility for high speed and precision operation, optimal integration of smart (active) materials into the structure of such machines, and some related issues are discussed.
A Systematic Method for Optimal Integration of Smart Materials Into the Structure of High Speed Mechanisms
Authors: Yuan L. , Rastegar J.
Published: February 2021

A systematic method is presented for the integration of smart (active) materials based actuators into the structure of mechanical systems in general and mechanisms with closed-loop chains in particular for the purpose of modifying the output motion of the system. In the resent study, the method is applied to a four-bar linkage mechanism with a constant input velocity for the purpose of eliminating the high harmonic component of the output link motion. By eliminating the high harmonic component of the output motion of a mechanism, the potential vibrational excitation that the mechanism can impart on the overall system and its own structure is greatly reduced. The resulting system should therefore be capable of operating at higher speeds with increased precision. For mechanisms with rigid links, the primary source of high harmonic motions is the nonlinearity of the kinematics of the closed-loop chain. The usually less prominent high harmonic motions due to joint and/or structural flexibility may be eliminated in a similar manner and will be addressed in future publications.
A Pseudo-Rigid-Body Model for Functionally Binary Pinned-Pinned Segments Used in Compliant Mechanisms
Authors: Edwards Brian T. , Jensen Brian D. , Howell Larry L.
Published: February 2021

The pseudo-rigid-body model concept allows compliant mechanisms to be analyzed using well-known rigid-body kinematics. This paper presents a pseudo-rigid-body model for initially circular functionally binary pinned-pinned segments that undergo large, nonlinear deflections. The model approximates the functionally binary pinned-pinned segment as three rigid members joined by pin joints. Torsional springs placed at the joints model the segment’s stiffness. This model has been tested by fabricating several such segments from a variety of different materials. An example mechanism incorporating functionally binary pinned-pinned segments is also presented.
Regions of Feasible Point-to-Point Trajectories in the Cartesian Workspace of Fully-Parallel Manipulators
Authors: Chablat Damien , Wenger Philippe
Published: February 2021

The goal of this paper is to define the n-connected regions in the Cartesian workspace of fully-parallel manipulators, i.e. the maximal regions where it is possible to execute point-to-point motions. The manipulators considered in this study may have multiple direct and inverse kinematic solutions. The N-connected regions are characterized by projection, onto the Cartesian workspace, of the connected components of the reachable configuration space defined in the Cartesian product of the Cartesian space by the joint space. Generalized octree models are used for the construction of all spaces. This study is illustrated with a simple planar fully-parallel manipulator.
Motion Planning for Multi-Robot Assembly Systems
Authors: Bonert M. , Shu L. H. , Benhabib B.
Published: February 2021

This paper addresses a multi-robot optimal assembly planning problem which in essence is an augmented Travelling Salesperson Problem (TSP+). In our TSP+, both the “salesperson” (a robot with a tool) as well as the “cities” (another robot with a workpiece) move. Namely, in addition to the sequencing of tasks, further planning is required to choose where the “salesperson” should rendezvous with each “city”. The use of a genetic algorithm (GA) is chosen as the search engine for the solution of the multi-robot TSP+ optimization. As an example industrial application the optimization of the electronic-component placement process is addressed. In the most generalized component-placement system configuration, the placement robots meet the component delivery systems (CDSs) at optimal rendezvous locations for the pick-up of components and subsequently meet the printed circuit board (on the mobile XY-table) at optimal rendezvous locations for their placement. In addition to the solution of the component-placement sequencing problem and the rendezvous-point planning problem, the collision-avoidance issue is also addressed.
An Automatic Method for Finding the Assembly Configurations of Planar Non-Single-Input-Dyadic Mechanisms
Authors: Foster David E. , Cipra Raymond J.
Published: February 2021

This paper examines the problem of identifying the assembly configurations (ACs), also called circuits, of planar non-single-input-dyadic (NSID) mechanisms. An SID mechanism is a multi-loop mechanism which can be defined by adding one loop at a time such that the mechanism has one degree of freedom (DOF) after each loop is added. An NSID mechanism is any mechanism that does not meet the SID criterion. This includes all multi-DOF mechanisms, and some complex single-DOF mechanisms. An automatic, method is presented which allows a computer to determine the ACs of an NSID mechanism. For single-DOF mechanisms, the ACs are represented by curves drawn in a plane represented by two joint variables. For multi-DOF mechanisms, the ACs consist of one or more regions in the plane, which are defined by the curves that bound, them. The automated method finds these bounding curves, and then determines which curves belong to the same region, and which regions belong to the same AC. Mechanisms with pin joints and sliding joints are considered.
Manipulator Performance Criteria Based on Kinematic, Dynamic, and Compliance Models
Authors: Pryor Mitch , Van Doren Matthew , Tesar Delbert
Published: February 2021

Currently, few criteria are available that identify a redundant robot’s ‘optimal’ configuration. Criteria developers have been compelled to design computationally efficient metrics in order to maintain necessary control cycle rates this requirement is diminishing in importance with increasing computer performance, allowing designers to implement more complex and effective criteria into the manipulator’s control algorithms. This paper presents a wide variety of criteria that will aid in pinpointing optimal configurations in redundant manipulators. In developing these criteria, the counterproductive (but often necessary) requirement of minimizing the computation rate per criterion is largely ignored.

These new criteria are intended for two purposes: (1) the trajectory optimization of redundant manipulators and (2) design optimization for configuring link and joint modules in any manipulator. The criteria presented are derived from the geometric (both 1st and 2nd order), dynamic, and compliance models of a manipulator. All criteria are simulated on a 7DOF serial manipulator, and several results are presented here.
Kinematic Analysis and Modeling of Traction Drive CVT
Authors: Zhang X. , Tobler W. , Zhang Y.
Published: February 2021

This paper presents a systematic model for the design and analysis of toroidal traction drive continuously variable transmissions (CVT). The contacts between the input disk, the roller and the output disk of the traction drive are formulated using classical Hertzian contact theory. The traction force and side slip force occurring in CVT operation are modeled based on elasto-hydrodynamic theory and are correlated to the traction drive geometric and kinematic parameters. The model allows for the quantitative analysis of traction drive operation under specified torque inputs and over the desired ratio range.
On the Embedded Kinematic Fractionation of Epicyclic Gear Trains
Authors: Liu Chia-Pin , Chen Dar-Zen
Published: February 2021

In this paper, the concept of kinematic fractionation is introduced for epicyclic gear trains (EGTs) which contains structural fractionation as a degenerate case. Kinematic fractionation provides a viewpoint to determine the type of fractionation of an EGT by distinguishing the independent transmission path(s) inside. With the concept of kinematic fractionation, kinematically independent group(s) embedded in an EGT can be identified. A composition list, which depicts the links and the link connection in the associated group, is used to determine the type of fractionation. It is found that most previously enumerated structurally non-fractionated EGTs in the literature are kinematically fractionated. It is shown that a structurally non-fractionated EGT may be kinematically fractionated while a structurally fractionated EGT must be kinematically fractionated. The concept of kinematic fractionation can lead to efficient topological analysis of EGTs with physical comprehension.
Integrated Design and Control for a Programmable Four-Bar Linkage
Authors: Li Q. , Zhang W. J. , Guo L. S.
Published: February 2021

As the demand increases for machines of high accuracy, high speed and high stiffness, programmable closed-loop linkages emerge in the development of modern machinery. A mechatronic design methodology is proposed in this paper for the integrated design of mechanical structure and control algorithm for a programmable closed-loop mechanism system. This design methodology suggests a negative mass redistribution scheme, which follows the principle of a shaking force/shaking moment balancing scheme, for the modification of an existing four-bar mechanism, with the aim to obtain a simple system dynamic model and thus to facilitate controller design. In consequence, motion tracking performance and vibration behavior of the linkage system are significantly improved by simply applying a conventional PD control algorithm. The dynamic performances are further improved by using a model-based controller. The effectiveness of the proposed methodology has been verified by simulation studies.
Design of New Rotors for Trapping-Free and High-Sealing Lobe Pumps
Authors: Liu Hung-Cheng , Tong Shih-Hsi , Yang Daniel C. H.
Published: February 2021

A method for the design of new rotor profiles for high-sealing lobe pump is presented in this paper. The objective of this paper is to improve the sealing of lobe pumps by designing chamber profile conforming rotors. The deviation function method is adopted and the resultant rotor profiles are trapping-free and have C1 continuity. A design procedure for rotor generation is also developed. A sealing index is defined to evaluate the sealing property of lobe pumps. Our results show that it is possible to design many new rotor profiles that have better sealing property than conventional involute rotors.