bluuebunny/crossref_metadata_2025 huggingface dataset:
A Declarative Feature-Based Cross Sectional Design Tool for Surface Micromachined MEMS
Authors: Gao Feng , Sarma Radha
Published: November 2020

Currently MEMS designers begin the geometric design of a new device by creating the masks that would lead to a geometric model. At the macro-level, this would be analogous to generating a geometric model from the tool paths, which would be a very tedious task. In contrast to MEMS designers, designers of macro-devices have the advantage of starting with a geometric model and of being able to directly visualize or manipulate their designs. The geometric model is then queried to generate manufacturing-related data. In the case of surface micromachined MEMS, until very recently, there has been no systematic means to automatically generate the mask data after a geometric model of the MEMS device has been refined through behavioral simulations. This has resulted in the lack of geometric design tools that would potentially aid the MEMS designer in creating MEMS devices.

This paper focuses on developing a declarative, feature-based design tool for the cross sectional design of surface micromachined MEMS, which enables MEMS designers to create fabrication-ready models of MEMS devices in an intuitive environment that is transparent to the fabrication process. The structured nature of MEMS fabrication processes has been exploited to develop a design-by-features approach tailored to MEMS design. In comparison to most macro-design tools where a design-by-features approach does not provide full flexibility, in the case of MEMS, the structured nature of the fabrication process allows for a comprehensive definition of design features that can be systematically mapped to fabrication features. In addition, feature dependency graphs and constraint graphs enable feature reparametrization leading to the easy manipulation of MEMS designs.
Relative Cooling: Part II — Design Considerations and Efficiency
Authors: Constantin Sandu , Brasoveanu Dan
Published: November 2020

Cooling systems with liquid for gas turbine engines that use the relative motion of the engine stator with respect to the rotor for actuating the coolant pump can be encapsulated within the engine rotor. In this manner, the difficult problem of sealing stator/rotor interfaces at high temperature, pressure and relative velocity is circumvented. A first generation of such cooling systems could be manufactured using existing technologies and would boost the thermal efficiency of gas turbine engines by more than 2% compared to recent designs that use advanced air-cooling methods. Later, relative cooling systems could increase the thermal efficiency of gas turbine engines by 8%–11% by boosting the temperatures at turbine inlet to stoichiometric levels and recovering most of the heat extracted from turbine during cooling. The appreciated high reliability of this cooling system will allow widespread use for aerospace propulsion.
Optimum Design Using Search Agents
Authors: Miyashita Tomoyuki , Yamakawa Hiroshi
Published: November 2020

Many optimization methods and practical softwares have been developing for many years and most of them are very effective, especially to solve practical problems. But, non-linearity of objective functions and constraint functions, which have frequently seen in practical problems, has caused a difficulty in optimization. This difficulty mainly lies in the existence of several local optimum solutions.

In this study, we have proposed a new global optimization methodology that provides an information exchange mechanism in the nearest neighbor method. We have developed a simple software system, which treated each design point in optimization as an agent. Many agents can search the optima simultaneously exchanging the their information. We have defined two roles of the agents. Local search agents have roles on searching local optima by such an existing method as the steepest decent method and so on. Stochastic search agents investigate the design space by making use of the information from other agents. Through simple and several structural optimization problems, we have confirmed the advantages of the method.
Posture Prediction Versus Inverse Kinematics
Authors: Abdel-Malek Karim , Yu Wei , Mi Zan , Tanbour E. , Jaber M.
Published: November 2020

Inverse kinematics is concerned with the determination of joint variables of a manipulator given its final position or final position and orientation. Posture prediction also refers to the same problem but is typically associated with models of the human limbs, in particular for postures assumed by the torso and upper extremities. There has been numerous works pertaining to the determination and enumeration of inverse kinematic solutions for serial robot manipulators. Part of these works have also been directly extended to the determination of postures for humans, but have rarely addressed the choice of solutions undertaken by humans, but have focused on purely kinematic solutions. In this paper, we present a theoretical framework that is based on cost functions as human performance measures, subsequently predicting postures based on optimizing one or more of such cost functions. This paper seeks to answer two questions: (1) Is a given point reachable (2) If the point is reachable, we shall predict a realistic posture. We believe that the human brain assumes different postures driven by the task to be executed and not only on geometry. Furthermore, because of our optimization approach to the inverse kinematics problem, models with large number of degrees of freedom are addressed. The method is illustrated using several examples.
On the Extraction of Kinematic Behavior From Optimal Compliant Topologies With Application to Number Synthesis of Linkages
Authors: Saxena Anupam , Ananthasuresh G. K.
Published: November 2020

This paper presents a number of systematically designed compliant topologies and discusses how the intrinsic kinematic behavior can be extracted from them. This is then applied to the number synthesis of linkages. Many techniques developed for number synthesis of linkages enumerate numerous possible kinematic chains, but few can select the best configuration among them. A systematic computational approach that can select the best configuration based on kinetostatic design specifications is presented here. This is a serendipitous result that transpired when two well-developed design techniques for compliant mechanisms were combined. A number of examples with non-intuitive design specifications are included to illustrate the new approach to number synthesis. The examples also illustrate that the kinematic behavior is aptly captured in the elastic mechanics-based topology optimization method to compliant mechanism design. Dimensional synthesis is also accomplished in the same procedure, which is an added benefit of this approach.
Towards the Design of Heterogeneous Compliant Mechanisms
Authors: Yin Luzhong , Ananthasuresh G. K.
Published: November 2020

Inspired by nature’s multi-material compliant designs and the capability of modern manufacturing methods to make multi-material components without assembly, and motivated by the versatility and enhanced functionality with multi-material designs, we formalize the notion and the design of heterogeneous compliant mechanisms. In the topology optimization of compliant mechanisms, a fictitious density function is often used for material interpolation to overcome the computational difficulties encountered in the large “0-1” type integer programming problem. In this paper, we illustrate that a gradually formed continuous peak function can be used for material interpolation. One of the advantages of introducing the peak function is that multiple materials can easily be incorporated into the topology optimization without increasing the number of design variables. By using the peak function and the optimality criteria method, we synthesize compliant mechanisms with multiple materials with and without the material resource constraint. The numerical examples include the two, three, and four material designs where void is treated as one material. This new design method enables us to optimally juxtapose stiff and flexible materials in heterogeneous compliant mechanisms that can be built using a variety of modern manufacturing methods.
Solution Selectors: A User-Oriented Answer to the Geometric Constraint Multiple Solution Problem
Authors: Bettig Bernhard , Shah Jami
Published: November 2020

The development of solid modeling to represent the geometry of designed parts and the development of parametric modeling to control the size and shape have had significant impacts on the efficiency and speed of the design process. Designers now rely on parametric solid modeling, but surprisingly often are frustrated by a problem that unpredictably causes their sketches to become twisted and contorted. This problem, known as the “multiple solution problem” occurs because the dimensions and geometric constraints yield a set of non-linear equations with many roots. This situation occurs because the dimensioning and geometric constraint information given in a CAD model is not sufficient to unambiguously and flexibly specify which configuration the user desires.

This paper first establishes that only explicit, independent solution selection declarations can provide a flexible mechanism that is sufficient for all situations of solution selection. The paper then describes the systematic derivation of a set of “solution selector” types by considering the occurrences of multiple solutions in combinations of mutually constrained geometric entities. The result is a set of eleven basic solution selector types and two derived types that incorporate topological information. In particular, one derived type “concave/convex” is user-oriented and thought to be very useful.
Development of Parallel Architecture Spatial Compliant Manipulators
Authors: Canfield S. L. , Beard J. W. , Parsons R. D. , Lobontiu N. , Paine M. , Paine J.
Published: November 2020

This paper will present the development of two spatial compliant manipulators suitable for fabrication at a miniature or micro level and positioning on a micro or nano scale. These compliant manipulators are based on a parallel architecture that provides rotational motion about two axes and translations in one to three directions. These compliant devices form the first in a class of such compliant manipulators that combine the characteristics of parallel manipulators with the low cost, small-scale capabilities resulting from a compliant structure design. These manipulators will be developed as lumped-compliance devices, having architectures with relatively rigid links and compliant joints designed to render nearly equivalent kinematic motion. Appropriate kinematic models are developed for design and control. The work is then demonstrated through development of a 3 degree-of-freedom miniature compliant manipulator (MCM) and a five degree-of-freedom (dof) compliant manipulator for micro-pointing applications.
Concurrent Parametric Design Using a Multifunctional Team Approach
Authors: Chen Li , Li Simon
Published: November 2020

A multifunctional team approach is suggested to tackle concurrent parametric design. In this approach, concurrent parametric design is modeled and formulated using optimization formalism in a multi-team computing environment, where each team is responsible for a distributed task as part of the whole design. To formalize a design task, the goal and constraints of each team are expressed as analogous to those treated in an optimization problem. The provision of satisfaction metrics is for quantifying how each team, from its perspective, favors a generated design. Coordination paradigms are formalized with characterization of the underlying team interactions in multi-team design. The notions of responsibility and controllability are introduced to regularize design protocols so that the complexity of modeling the mixed team design can be handled. As a result, a generalized team model is constructed to facilitate multi-team based design optimization, which is further illustrated through a design example.
The Use of Metamodeling Techniques for Optimization Under Uncertainty
Authors: Jin Ruichen , Du Xiaoping , Chen Wei
Published: November 2020

Metamodeling techniques have been widely used in engineering design to improve the efficiency in simulation and optimization of design systems that involve computationally expensive simulation programs. Many existing applications are restricted to deterministic optimization. Very few studies have been conducted on studying the accuracy of using metamodels for optimization under uncertainty. In this paper, using a two-bar structure system design as an example, various metamodeling techniques are tested for different formulations of optimization under uncertainty. Observations are made on the applicability and accuracy of these techniques, the impact of sample size, and the optimization performance when different formulations are used to incorporate uncertainty. Some important issues for applying metamodels to optimization under uncertainty are discussed.
Computer Assisted Navigation Systems for Hip and Knee Reconstructive Surgery: Evaluation of Traditional Surgical Technique
Authors: DiGioia Anthony M. , Picard Frederic , Jaramaz Branislav , Sell David , Moody James C. , Playkseychuk Anton , Levison Tim J. , Nikou Constantinos , LaBarca Richard S. , Muir Patrick
Published: November 2020

In this paper we describe a surgical navigation system named HipNav (Hip-Navigation) for THR and KneeNav (Knee-Navigation) for TKR with an emphasis on using these systems as a real time intraoperative measurement tool (these enabling technologies are the surgical toolbox of the future). This approach will permit the direct comparison of patient outcomes with measurable surgical techniques.
Rational Design Automation by Dichromatic Graphs
Authors: Escanaverino Jose Martinez , Soriz Jose A. Llamos , Toll Alejandra Garcia , Cardenas Tania Ortiz
Published: November 2020

As the complexity of mechanical design increases, due to larger size mathematical models, the need for rational design procedures also goes up. As shown elsewhere, dichromatic graphs have proven their value as tools for the algorithmic education of mechanical engineers. This paper analyzes the worth of such graphs as a means to achieve rational design solutions in complex industrial problems. The paper covers plant maintenance and research & development professional case studies. A real-life problem in electromechanical system reengineering is the first application example. Attention is also given in the paper on the partitioning of large problems, involving many variables and relations. The design of a planetary gear unit, with a three-digit number of elements in the mathematical model, is an example problem in this area. In addition, changes and extensions to the computational problem solving theory are included.
Automatic Determination of the Small Displacements in a Mechanical Assembly of Two Parts
Authors: Forster Charles , Doré Emmanuel
Published: November 2020

Herein is proposed an automatic method by which the precision of a joint realized by the mechanical assembly of two parts may be totally determined. This precision depends on the dimensional and geometrical defaults existing in the parts, and is materialized by additional small displacements of the parts superposed with the kinematics of the joint.

In a first step, the parts are represented by their geometrical entities, and the possible contacts existing between these entities. By ≪ sliding ≫ the parts around their nominal position, i.e. by opening or closing contacts between surfaces, one defines a new configuration of the assembly.

In a second step, we give the conditions that this new configuration must fulfill to be physically acceptable. No parasitical motion is accepted, it must be possible to compute the small displacement torsor between the two configurations. And finally, no geometrical interferences are tolerated between the parts.

In a third step, we apply this method on a simple but instructive bidimensional example.
Modeling of an Electroactive Steerable End-Effector for Minimally Invasive Surgery
Authors: Aguilera William M. , Frecker Mary I. , Haluck Randy
Published: November 2020

A model has been developed to design a new active, steerable end-effector for minimally invasive surgery. Active material is incorporated into the surgical instrument to increase the degrees of freedom available to the surgeon. This paper focuses on the modeling of the end-effector using both piezoelectric ceramic and electroactive polymer (EAP) materials. The end-effector design consists of a number of bimorph actuator sections in series with each active layer being individually controlled. Each section may behave as either a bimorph or a unimorph actuator, where in the case of unimorph one of the active layers is passive. By varying the strength and direction of the electric field across each section, a prescribed overall shape can be achieved to allow the user to steer the device. The piezoceramic device is modeled using strain energy methods to predict the quasi-static force-deflection behavior. In the EAP model, experimental data for the electrostrictive P(VDF-TrFE) copolymer is used to model the non-linear relationship between the electric field and the induced strain. Due to the large deflections achievable with the EAP, a model for large deflections beams is also used. Modeling is carried out using MATLAB and then the behavior of piezoelectric ceramic is compared to that of electro-active polymer (EAP).
Design for Energy Absorption: A Topology Optimization Approach
Authors: Gea Hae Chang , Luo Jianhui
Published: November 2020

Topology optimization for energy absorption is studied in this paper. Unlike conventional mean compliance formulation, this paper considers two main functions of vehicle structure: stiffness and energy absorption. During its normal usages, stiffness is chosen as the design objective. During impact, portion of vehicle structures absorbs impact energy while other part maintains the structural integrity. Therefore, we implemented a regional strain energy formulation to topology optimization. Sensitivity for regional strain energy is derived from the adjoint method. Numerical results from the proposed formulation are presented.
Perfect Static Balance With Normal Springs
Authors: te Riele Freek L. S. , Herder Just L.
Published: November 2020

In biomechanical engineering, gravity balancers are often used in orthoses carrying the weight of paralyzed limbs. In these applications, simplicity is an insuperable demand. However, known gravity balancers do not combine simplicity with perfect balance. This paper describes several gravity equilibrators providing perfect static balance. As opposed to many known solutions, the proposed balancers incorporate normal off-the-shelf springs, rather than the zero-free-length springs (springs with a length equal to zero when not preloaded or loaded externally) usually employed. The conceptional synthesis is presented, dimensional design criteria are derived, and prototypes are shown. Based on the prototype’s working principle, an ankle prosthesis, which stabilizes the patient, will be developed.
Development of 5mm-Trocar Laparoscopic Forceps With Mechanical Force Feedback
Authors: van der Pijl Albert J. , Herder Just L.
Published: November 2020

In minimally invasive surgery, surgeons are deprived of direct contact with the patient’s tissue. All manipulation, including diagnostic palpation, is carried out via long and slender instruments, inserted through small trocars inserted in the skin. Due to poor mechanical characteristics, such as internal friction, backlash, and non-linear force transmission functions, current instruments allow only marginal force feedback. Consequently, surgeons lack a major source of vital information, resulting in reduced safety and grasping forces far greater than necessary. Previous research lead to the design of a 10mm-trocar grasper with low friction and an outstanding force transmission characteristic. The present study was conducted to develop this prototype into a clinically applicable instrument which can be used in 5mm-trocar therapy, by redesigning the mechanism while maintaining the excellent mechanical characteristics. This resulted in a clinical prototype, still according the patented rolling link design but in a different embodiment, now also matching the additional specifications. Mechanical testing showed that the mechanical efficiency of the 5mm-trocar version is as high as in the original version. The 5-mm-version will now be used for further optimization and clinical testing.
CyberAgent: Collaborative Agents for Distributed Applications Over the Internet
Authors: Shi J. , Huang G. Q. , Mak K. L.
Published: November 2020

This paper is mainly concerned with developing the broking agents called CyberAgent for collaborations among distributed applications over the Internet. Based on a flexible relationship model — CyberWorkflow — among CyberAgents, parameters can be transferred among applications with dataflows between CyberAgents, and applications are to be activated sequently according to controlflows among CyberAgents. Details of CyberAgent and CyberWorkflow are discussed in this paper. A case study is introduced in this paper to demonstrate how eight CyberAgents can be used in a Lucas DFA application suit to facilitate collaborations among eight sub-applications, each one occupying an individual CyberAgent. Concluding discussion is provided at the end of this paper.
A Dedicated CAD/CAM System for 5-Axis Machining of Marine Propeller
Authors: Youn Jae-Woong , Jun Yongtae , Park Sehyung
Published: November 2020

The manufacture of a marine propeller typically requires long lead-time to generate 5-axis tool paths. It usually takes several days to manufacture a satisfactory propeller with a general purpose CAD/CAM system. This paper proposes a novel methodology for tool path generation of 5-axis machining of marine propellers. Using the geometric characteristics of propellers, the system first computes check vectors and then generates interference-free tool paths. An iterative NURBS modeling technique is used to improve the accuracy of the models and to increase the productivity. The system has been implemented with C++ and OpenGL graphic library on the Windows system. The system validation and sample results are also given and discussed.
Effectiveness of Neural Network and Genetic Algorithm in Hull Form Design
Authors: Khondoker M. Reaz H. , Rahman Chowdhury Mofizur , Islam Mohammad Mahfuzul
Published: November 2020

This paper aims at developing a fully automated hull form design technique employing an Neural Network and Genetic Algorithm methods resulting in accelerated convergence. For generating an input data that will be, by and large, a close relative of the desired hull, a linear relation has been assumed between the half breadth of different sections and principal dimensions (length, breadth, draft or (displacement)1/3) of a particular type of vessel. Compared to starting with a random value of the input, this technique resulted in faster convergence. The weight matrix for each of these parameters is produced from data obtained from the population. The half-breadth table for a new vessel can be obtained by multiplying the weight matrix with corresponding parameter. However, the half-breadth table obtained in such way may not provide the required displacement and speed of the vessel. Therefore, some readjustments of some of the principal dimensions are required. Neural Networks (Wasserman, 1989) has been used to find the required values of such improved design parameters (principal dimensions). The final design process consists of searching for the exact solution by examining several generations generated by the GA (Goldberg, 1989). The convergence criterion is the summed offset error, which is to be within the envelope defined by the tolerances. Since GA doesn’t guarantee fairness of the surface of the hull form, B-spline curve fitting method is used to obtain a fair hull. Thus, the hull form generated through this process is fully automated, accurate and having fair surface. The technique is also found to be an efficient one.
A Study on Shape Optimization Using Affine Transformation
Authors: Kitayama Satoshi , Yamakawa Hiroshi
Published: November 2020

This paper presents a new method to determine an optimal shape using affine transformation which is used in the field of Computer Aided Design (CAD), linear programming, and etc. We use affine transformation as coordinate transformation. Affine transformation is a linear transformation, so that shapes transformed must be linearly.

Shape optimization of a inclined beam for example, we can deal with in the following manner. We define a simple cantilever beam first in initial design domain, and calculate an optimal shape. Then we use affine transformation remaining with optimal shape calculated in simple design domain and get to an optimal shape of the inclined beam. To compare with an optimal shape obtained by our proposed method, we calculate an optimal shape directly by conventional method in the same design domain after coordinate transformation. We show that affine transformation plays a role as scaling to structural optimization by finite element method and that necessary and sufficient conditions between design variables and shape transformation matrix may exist to get an exact optimal shape. We treat some numerical examples by our proposed method. In numerical examples, we consider shape optimization of inclined cantilever beam for simplicity. We show that some stepwise linear optimal shapes could be expressed from an optimal shape of a simple cantilever beam by using affine transformation. Optimal shape calculated by our method can obtain easily and speedy. Through some numerical examples, we could examine effectiveness of our proposed method.
Large Deformation Behavior of Compliant Mechanisms
Authors: Joo Jinyong , Kota Sridhar , Kikuchi Noboru
Published: November 2020

This paper presents a non-linear formulation for size and shape optimization of compliant mechanisms using tapered beam elements. Designs based on linear and nonlinear formulations are compared using a stroke amplification mechanism example. Also, the scaling effect of the compliant mechanism is investigated.
A Robot for Hand Rehabilitation: A Continuation of the MIT-MANUS Neuro-Rehabilitation Workstation
Authors: Jugenheimer Kristin A. , Hogan Neville , Krebs Hermano I.
Published: November 2020

A novel robot for hand rehabilitation is described. The robot is a continuation of the work done with MIT-MANUS, a robot-aided neuro-rehabilitation workstation. Flexure bearings are used in conjunction with a cable-drive transmission system. The requirements of the robot and key design elements are described. We are presently completing assembly and should commence shortly with system characterization and clinical testing.
Design of Passive Reconfigurable Manipulation Assistive Aids
Authors: Nie Xichun , Krovi Venkat
Published: November 2020

Multi-jointed mechanical systems typically possess excess degrees-of-freedom, which often are neither required nor used in performing typical manipulation tasks. These excessive degrees of freedom then need to be reduced by application of constraints, either actively by suitable control or passively in hardware, prior to task performance.

Our interest is in creating articulated manipulation assistive aids, which combine the motion flexibility due to the multiple articulations with the simplicity of reduced degree-of-freedom control and actuation due to the presence of hardware mechanical constraints.

Specifically we investigate the process of design and prototyping of such reduced-degree-of-freedom manipulators to closely approximate desired planar paths. We then examine design enhancements to permit easy reconfiguration for different sets of paths. Finally, special attention is paid to the creation of a prototype with the ability to be reconfigured for multiple sets of paths, by a controlled variation of the principal structural parameters.
Formulation of Dynamic Loads Generated by Lubricated Journal Bearings
Authors: Alshaer B. J. , Lankarani H. M.
Published: November 2020

This paper addresses the analytical evaluation of dynamic pressures and forces produced by the lubricant in a lubricated long journal bearing under dynamic loading. An evaluation of accuracy of the widely adopted Ott’s solution is conducted. The results show that when the journal center is moving toward the center of the bearing and the eccentricity ratio is high, the force formulation according to Ott’s solution give inaccurate results. Differences as high as 93% is found between Ott’s analytical solution and the numerical solution for certain conditions. Starting from Reynolds partial differential equation of lubrication theory, a new formulation for the dynamic characteristics of lubricated long journal bearing under dynamic loading is presented. The analytical integrations were conducted utilizing the Sommerfeld variable. The lubricant forces calculated at certain instants of time showed exact match with the numerical solution, which is not the case with Ott’s solution. The pressure distribution in the new formulation showed a slight difference compared to the Ott’s solution. The methodology presented in the new formulation to calculate the zero pressure angles at any instant of time showed exact match with the numerical results regardless of sharp changes in the pressure between the positive and negative regions. The new formulation is utilized in evaluating the transient and steady state characteristics of lubricated long journal bearing under unidirectional constant load and the results arc compared with the Ott’s solution.
Dynamics of a Multibody Mechanical System With Lubricated Long Journal Bearings
Authors: Alshaer B. J. , Lankarani H. M. , Shivaswamy S.
Published: November 2020

Clearances exist in different kinds of joints in multibody mechanical systems, which could drastically affect the dynamic behavior of the system. If the joint is dry with no lubricant, impact occurs, resulting in wear and tear of the joint. In practical engineering design of machines, joints are usually designed to operate with some lubricant. Lubricated journal bearings are designed so that even when the maximum load is applied, the joint surfaces do not come into contact with each other. In this paper, a general methodology for modeling lubricated long journal bearings in multibody mechanical systems is presented. This modeling utilizes a new method of solving for the forces produced by the lubricant in a dynamically loaded long journal bearing. A perfect revolute joint in a multibody mechanical system imposes kinematic constraints, while a lubricated journal bearing joint imposes force constraints. As an application, the dynamic response of a crank-slider mechanism including a lubricated journal bearing joint between the connecting rod and the slider is considered and analyzed. The dynamic response is obtained by numerically solving the constraint equations and the forces produced by the lubricant simultaneously with the differential equations of motion and a set of initial conditions numerically. The results are compared with the previous studies performed on the same mechanism as well a dry clearance joint. It is shown that in a multibody mechanical system, the journal bearing lubricant introduces damping and stiffness to the system. The earlier studies previous predict that the order of magnitude of the reaction moment is twice that of a perfect revolute joint. The proposed model predicts that the reaction moment is within the same order of magnitude of the perfect joint simulation case.
Effective Generation of Pareto Sets Using Genetic Programming
Authors: Eddy John , Lewis Kemper
Published: November 2020

Many designers concede that there is typically more than one measure of performance for an artifact. Often, a large system is decomposed into smaller subsystems each having its own set of objectives, constraints, and parameters. The performance of the final design is a function of the performances of the individual subsystems. It then becomes necessary to consider the tradeoffs that occur in a multi-objective design problem.

The complete solution to a multi-objective optimization problem is the entire set of non-dominated configurations commonly referred to as the Pareto set. Common methods of generating points along a Pareto frontier involve repeated conversion of multi-objective problems into single objective problems using weights. These methods have been shown to perform poorly when attempting to populate a Pareto frontier. This work presents an efficient means of generating a thorough spread of points along a Pareto frontier using genetic programming.
Automatic Synthesis of Cooling System Design for Plastic Injection Mould
Authors: Li C. L.
Published: November 2020

This paper reports an automatic algorithm that synthesizes the design of cooling system for plastic injection mould. Automation in cooling system design is an important research area that has not received much attention. In the proposed method, a building block approach to design synthesis is adopted. Given a plastic part and a library of pre-defined cooling sub-systems, the algorithm first decomposes the part into features known as cooling features. For each cooling feature, the corresponding cooling sub-systems are retrieved from the library. The cooling sub-systems are then modified and combined into an initial design of the cooling system for the entire plastic part. The performance of the initial design is verified by using CMold analysis. A design synthesis program has been implemented and an example is given to illustrate the feasible of the proposed algorithm.
Support Structures Extraction for Hybrid Layered Manufacturing
Authors: Ruan Jianzhong , Zhang Jun , Liou F. W.
Published: November 2020

In a multi-axis metal hybrid layered manufacturing system, a combined laser material deposition and material removal system with more than 3-aixs mobility, sometimes support structures are necessary in the part building process, which prevent object from falling during deposition process. Since the support material is the same as build material, it is very difficult to remove the support material in the post processing stage. Thus, the support material must be machined off. Therefore, the geometry information of support structures is important for the machining process. In this paper, a method is presented to extract support structures automatically. Two types of support structures, trapped and non-trapped, are classified in this paper and their extraction methods are discussed respectively.
Promoting Modularity in Evolutionary Design
Authors: Lipson Hod , Pollack Jordan B. , Suh Nam P.
Published: November 2020

Evolutionary design systems apply principles inspired from biological evolution to automate machine design. These systems have been shown to generate simple designs for simple tasks — but their practical ability to scale up to higher complexities remains questioned. One of the keys to accomplishing higher-level evolutionary design is the ability of the process to identify and reuse knowledge discovered at lower levels, thus scaling its search capacity. One way to capture this knowledge is in the form of reusable building blocks — modules. In this paper we define modularity and discuss several approaches to promoting modularity in evolutionary design systems. In particular, we propose a new mechanism that can enhance modularization. This mechanism is based on the observation that designs that exhibit modularity have higher adaptability and consequently have better survival rates under changing requirements. Contrary to other techniques, this is a weak (indirect) formulation that docs not require representation of partial solutions or definition of a genotype from which a design is developed. We demonstrate this principle on an abstract general design problem on which modularity can be statistically quantified.
Tool Path Generation Based on B-Spline Wavelets
Authors: Narayanaswami Ranga , Pang Junhua
Published: November 2020

Tool path generation is a fundamental problem in numerical control machining. Typical methods used for machining 2.5D objects include generation of offset contours using trimmed offset curves and zigzag sequences. The offset contours result in unnecessary detailed curves far away from the object boundary. The zigzag sequences result in frequent stops and changes in tool direction. In this paper we present a novel approach for tool path generation based on wavelet theory. The theory of wavelets naturally leads to a simple cut sequence algorithm that provides valid and efficient coverage of the machined surface. The classical analytical and algebraic complexity in tool path planning is also reduced. In this paper, curves are represented by endpoint interpolating B-splines and their corresponding wavelets. Design and manufacturing examples are also presented in this paper.
A Direct Statistical Formulation to Account for Uncertainty in Mechanical Design: Proof-of-Concept
Authors: Brindavan Hemanthkumar , Ogot Madara
Published: November 2020

In recent years there has been an increased need to account for uncertainty in design as industry strives to reduce the amount of physical prototyping in favor of faster and cheaper computer simulations. Traditionally, incorporation of uncertainty in design models has been achieved mainly through either Monte Carlo simulations or Mean Value (MV) approximations. The former, while relatively accurate, can be computationally prohibitive. MV approximations on the other hand, trade accuracy for higher computational speed. The proposed direct statistical formulation is a Corrected Mean Value (CMV) approximation. The CMV exploits the correlation between the parameter coefficients of variation and the fractional error incurred using the MV approach to determine appropriate correction factors. Multiplication of the MV approximation by the correction term significantly reduces the error, without sacrificing computational speed. The approach therefore presents a more accurate approximation of the expected value of a function. This paper presents a numerical proof-of-concept of the CMV formulation. Several examples are presented to illustrate the efficacy of the proposed methodology.
Three-Equation Kinematic Models for the Human Knee Passive Motion Simulation
Authors: Di Gregorio Raffaele , Parenti-Castelli Vincenzo
Published: November 2020

Mathematical models are essential tools in the functional analysis of complicated biological structures such as the human knee joint. This paper presents two new mathematical models of the human knee for passive motion simulation. Both models comprise three scalar equations in four unknowns that can be reduced to one univariate polynomial equation, when a value of the mechanism’s generalized coordinate is given. The polynomial equation admits at most forty real solutions. Finally, the relationships to transform the employed joint coordinates into the joint coordinates usually employed in clinical practice are also reported.
Stable Evaluation of Probabilistic Constraint in Reliability-Based Design Optimization for Large Deformation Problem
Authors: Park Young H.
Published: November 2020

In this paper, Reliability-Based Design Optimization (RBDO) is carried out using two distinct ways, the Reliability Index Approach (RIA) and the Performance Measure Approach (PMA). It has been theoretically explained that RIA shows instability but PMA is stable and efficient in identifying a probabilistic failure mode in the RBDO process. The PMA is compared to RIA with regard to the stable evaluation of a probabilistic constraint in the RBDO using a large deformation problem. In addition, an efficient Design Sensitivity Analysis (DSA) method is developed to support reliability analysis and reliability-based optimization for a hyper-elastic structure with factional contact using a meshfree method. A numerical result is presented to demonstrate the comparative study between RIA and PMA.
Concept Development of a Tie-Down Temporary Concrete Barrier System
Authors: Bielenberg Robert W. , Reid John D.
Published: November 2020

Design for safety includes not only the vehicle and occupant protection system but also the structures that vehicles hit. One such example includes temporary concrete barriers. Often in work zones on bridges there is very little room available for barrier deflections when impacted by errant vehicles. Thus, deflections of the barriers must be severely restricted to prevent the barrier from being deflected off of the deck, followed closely by the striking vehicle.

A tie-down design was generated consisting of a steel base plate with two vertical steel tubes, each with a crosshead tube blockout. Nonlinear finite element analysis of the new design focused on gauging the performance of the design as well as optimizing the structural requirements and anchor loads. Results of simulating a full-scale crash test predicted that the proposed design would be capable of safely constraining the barriers during an impact event.
Elastick: A Vision Based Interface for Designing Spatial Curves and Surfaces
Authors: Suzuki Hiromasa , Fukushige Shinichi
Published: November 2020

Computer systems are widely used in mechanical design process, but their user interfaces and devices are not sufficient for designers to create sophisticated shapes. Various kinds of 3D input devices are not so useful either in terms of functions and costs. We propose a vision based interface called “Elastick” using an elastic stick and a digital camera which allows a designer to input smooth spatial curve very easily. It does not require any expensive, special devices and environments. The designer bends the stick to form a desired spatial curve. A digital camera is used to take an image of the stick, from which a spatial curve is reconstructed. A method developed by Pentland (PENTLAND, 1989) is used to reconstruct a spatial curve from a single image. In this paper, methods and algorithms used for Elastick are described and its application for generating mesh models are demonstrated.
Optimization for Vibration Reduction in Final Phase of Automotive Body Structural Design
Authors: Tsurumi Yasuaki , Nakagawa Toshiaki , Mori Nobuyuki , Yamakawa Hiroshi
Published: November 2020

In automotive body structural design, Computer Aided Engineering (CAE) has been widely used in order to evaluate noise, vibration, harshness (NVH). A CAE engineer has usually used a large-scale finite element model exceeding 1 million degrees of freedom to improve NVH performance criteria in the final design phase. It is, however, difficult for a CAE engineer to propose the modification candidate for the NVH reduction to an automotive designer in the phase, while good accuracy of the analysis is obtained by using the large-scale model. Only the small modifications can be performed for the NVH performance since configurations of main frame structures are usually determined with respect to crashworthiness in the phase. Therefore, a CAE engineer cannot provide the designer with effective information on time.

In this paper, a new optimal design method using a reduction scheme based on the physical coordinates under many design constraints regarding the crashworthiness is proposed in order to overcome above problems. Our proposed method finds out an optimal layout and stiffness value efficiently from the calculation results of the large-scale model. That is, we determine the appropriate location and additional scalar spring constants by minimizing the acceleration of the observation grid. The effectiveness and availability of this method are confirmed using an example.
The Use of the Voxmap Pointshell Method of Collision Detection in Virtual Assembly Methods Planning
Authors: Johnson Tom C. , Vance Judy M.
Published: November 2020

Virtual reality (VR) provides the ability to work with digital models in an environment that provides 3 dimensional interaction. This technology can be used to evaluate how humans interact with products before costly physical prototypes are built. One of the advantages of using VR technology in design evaluation is the ability to easily explore many different “what-if” design scenarios. One of the areas of current research in the use of VR is in assembly methods planning. As a result of prior work performed at Iowa State University, it became clear that collision detection is an important component in the development of virtual assembly methods planning applications. This paper describes the use of the Voxmap Pointshell method of collision detection as it is applied to a general purpose virtual assembly planning application.
Innovative Design of a Thrust-Eccentric Gear Coupling for Submerged-Motor-Driven PC Pumping System
Authors: Wang Shijie , Hong Guang
Published: November 2020

The gear coupling, which transmits axial compressive force, torque and relative eccentric motion, is the key component of progressing cavity (PC) pumping systems. This paper reports an innovative design of such a gear coupling especially used for submerged-motor-driven PC pumping system applied in oil fields. The novelty of this design is the synergy of a zero-tooth-difference internal meshing gear pair and a spherical pair. The principle of transmission and the determination of the key parameters such as the tangential and radial modification factors are described in this paper. Considering the reduced thickness of the gear tooth and the harsh operating condition of the PC pumping system, verification for the contacting and bending fatigue strength of the zero-tooth-difference gear pair is recommended, and the corresponding method is discussed.
Extraction of CAD Tool Requirements From Industry and From Experimental Design Projects
Authors: Wiegers Tjamme , Vergeest Joris S. M.
Published: November 2020

In spite of the advances of current CAD systems, the conceptual phases of design still suffer from lack of appropriate support tools. Contemporary research toward design support and automation puts substantial effort into the development of improved Computer-Aided Conceptual Design (CACD) and Computer-Aided Industrial Design (CAID) systems, both by industrial R&D and by science academia. However, there are indications that some of the persistent problems can only be solved if we more deeply understand what the requirements for the tools are. We extracted these requirements from two sources, from practicing designers in industry based on an inquiry, and from data generated in experimental design processes.

The inquiry indicated that improved CAD tools for conceptual design were lacking and would be welcomed if they were available. It was also explicitly revealed that even in the earliest phase of conceptual design, the enforcing of constraints to the designed shape was rated as crucial, besides an unlimited freedom of shape modeling as, e.g. offered by virtual claying. In general, a computer-based, early evaluation and analysis of design alternatives was ranked as the most urgent type of tool that should be developed.

Analysis of the protocol data from the design experiments revealed two items. First, the technical quality of the designs obtained by the test subjects suffered from a lack of intermediate evaluation. Second, the subjects often neglected to utilize an evaluation tool when it was provided.

From the extracted requirements we were able to derive recommendations for the research into better CACD tools. We also present some recent results that we obtained when we followed the recommendations.