bluuebunny/crossref_metadata_2025_split huggingface dataset:
Algebraic Acceleration of Finite Element Optimization; Four Modeling Errors in a Weldment Design
Authors: Sheppard S. D. , Wilde D. J. , Hsu Y.-L. 
Published: April 2021

Abstract
A method is proposed for incorporating finite element stress analysis into the constraints of an optimization model. To reduce the number of computationally intensive finite element analyses, the more accurate FEA plate model is approximated by an algebraic beam model having an adjustable factor whose value is determined by comparing FEA stresses with the corresponding beam theory predictions. This factor compensates both for the inaccuracies of beam theory and the effect of stress concentration. The algebraic form is retained to permit application of powerful optimization techniques not applicable directly to finite element models. The optimization problem is thus reduced to the determination of the single factor by linear interpolation. When tested on Keith’s well-known welded cantilever problem, the method needs only three FEAs. Keith’s model is also shown to suffer from four errors, of which three are remedied here. Because of special problem structure, the resulting design is correct for three of the four design variables, but the length of the weld cannot be determined without a better weld stress model.
Automatic Finite Element Mesh Generation Over Domains Comprised of Military Connected, Intersecting, Rigid Body-Movable Subdomains
Authors: Yang H. , Hoeltzel D. A. 
Published: April 2021

Abstract
A novel approach for the automatic generation and refinement of finite element meshes over nonconvex domains subdivided by multiply connected, rigid body-movable subdomains has been developed. The basis of this method relies on 1) the automatic insertion of nodes on the digitized boundaries and within the interiors of movable subdomains 2) the generation of superelement meshes, using the nodes which have been inserted on the subdomains, 3) determination of the points of intersection between adjacent subdomains following their rigid body movement, 3) ensuring the satisfaction of both interelement connectivity and compatability across subdomain boundaries which undergo rigid body movement along with the subdomains, and 4) the interactive refinement of userselectable subdomains using quadrilaterization for global refinement and triangularization for local refinement.
The creation of a finite element mesh for an acetabular cup inserted in a human pelvis, which is representative of a mesh generated over complex, two-dimensional, multiply connected subdomains, as employed in an orthopedic total hip replacement, serves as a realistic application of this approach and demonstrates its utility for expeditiously performing finite element-based, parametric design optimization studies.
3D Finite Element Analysis of Rolling Mill Bearings
Authors: Yuanke L. , Guanwei C. , Jun Y. , Qigui Z. , Caiyun Z. 
Published: April 2021

Abstract
The analysis and computation on stress and load-distribution state of rolling bearings via finite element method is one of the major studies on rolling bearings. This finite element analysis is much more complicated than that of common structures because of the contact problems existed in it and most of them can not be treated as plane prolems. This paper not only discusses the basic method of 3D contact finite element analysis and its solving technique in terms of the characteristics of four-row taper roller bearings attached to cold-rolling-mill work rolls, but also presents a simplified analytical model and computing results. The load-distribution curve under different working conditions is illustrated too in this paper.
Application of a Decomposition Technique for Treating a Shape Optimization Problem
Authors: Bremicker M. , Eschenauer H. 
Published: April 2021

Abstract
The range of application of structural optimization methods can be considerably enlarged by using decomposition techniques. In this paper a novel procedure is introduced to deal with such problems more efficiently. The mechanical structure resp. system is divided into several subsystems splitting up the design variables, objective functions, and constraints accordingly. The boundary state quantities of the subsystems and the global (i.e. subsystem overlapping) functions are approximated by a sensitivity analysis of the entire system using suitable approximation concepts. It is thus possible to optimize the subsystems independently. Variables, objective functions and constraints can be chosen arbitrarily; all coupling information is obtained from the sensitivity analysis by means of global information. The application of this technique is demonstrated by a two-dimensional shape optimization problem.
Using the Generalized Reduced Gradient Method to Handle Equality Constraints Directly in a Multilevel Optimization
Authors: Renaud J. E. , Gabriele G. A. 
Published: April 2021

Abstract
In recent years there have been several multilevel optimization algorithms proposed and implemented in design studies. Equality constraints are often imposed between levels in the optimization to maintain system and subsystem variable continuity. In most implementation studies these equality constraints are handled indirectly. This paper describes the utility of the Generalized Reduced Gradient (GRG) method for handling these equality constraints directly in a multilevel optimization. Two engineering design examples illustrate the methods effectiveness when incorporated in a multilevel linear decomposition scheme based on the Sobieski algorithm.
Parameter Sensitivity Analysis of a Large-Scale System With Several Components Interacting in Series
Authors: Torab H. 
Published: April 2021

Abstract
Parameter sensitivity for large-scale systems that include several components which interface in series is presented. Large-scale systems can be divided into components or sub-systems to avoid excessive calculations in determining their optimum design. Model Coordination Method of Decomposition (MCMD) is one of the most commonly used methods to solve large-scale engineering optimization problems. In the Model Coordination Method of Decomposition, the vector of coordinating variables can be partitioned into two sub-vectors for systems with several components interacting in series. The first sub-vector consists of those variables that are common among all or most of the elements. The other sub-vector consists of those variables that are common between only two components that are in series. This study focuses on a parameter sensitivity analysis for this special case using MCMD.
Extremal Behavior of One Parameter Families of Optimal Design Models
Authors: Rao J. R. J. , Papalambros P. Y. 
Published: April 2021

Abstract
Optimal design models contain parameters that are considered fixed during the optimization process. When these parameters change values, the mathematical properties of the model and the physical behavior of the underlying engineering system may change drastically. This article examines how large changes in one parameter affect the optimal solution and the type of singularities that may be encountered. The theory presented extends parametric optimization beyond the usual sensitivity analysis, and can be used as a modeling tool or as a rigorous treatment of related problems, such as multi-level decomposition. The algorithmic implementation and numerical examples are presented in a sequel article.
Optimal Design of Mechanical Components With Sizing, Configurational and Topological Consideration
Authors: Sandgren E. , Lee H. , El-Sayed M. 
Published: April 2021

Abstract
A methodology for the optimal design of structural mechanical components with sizing, configurational and topological consideration is presented. The optimization involves the minimization of structural weight subject to stress and deflection constraints. A finite element code with internally generated design sensitivities and general element connectivities is implemented in order to solve for the stresses and deflections in the structure. Beam elements with various crossectional configurations are considered. The generalized reduced gradient method is applied to solve the constrained nonlinear programming problem. A hierarchical design optimization approach is taken with topological issues considered at the upper level and geometric and crossectional issues considered at the lower level. An example involving the design of an automotive seat frame structure is presented to demonstrate the approach.
Robot Path Planning and Obstacle Avoidance: A Design Optimization Approach
Authors: Sandgren E. , Venkataraman S. 
Published: April 2021

Abstract
A design optimization approach to robot path planning in a two dimensional workplace is presented. Obstacles are represented as a series of rectangular regions and collision detection is performed by an operation similar to clipping in computer graphics. The feasible design space is approximated by a discrete set of robot arm and gripper positions. Control is applied directly through the angular motion of each link. Feasible positions which are located between the initial and final robot link positions are grouped into stages. A dynamic programming algorithm is applied to locate the best state within each stage which minimizes the overall path length. An example is presented involving a three link planar manipulator. Extensions to three dimensional robot path planning and real time control in a dynamically changing workplace are discussed.
A Dual-Purpose KBES for Preliminary Structural Design
Authors: Hart P. K. , Rodriguez J. 
Published: April 2021

Abstract
A prototype expert system for automatic preliminary shape synthesis is being developed. The purpose of this system is to generate preliminary designs which can be used either for basic engineering or as an initial solution in an optimization scheme. The developed prototype intends to emulate the conceptual-design/preliminary-redesign phases in the design process. Both phases have been modularized and developed under adequate computational shells. Modules requiring heuristic support are implemented in a LISP/KEE™ environment, the ones being computer-intensive are in C subroutines. Heuristics are applied in the initial design phase to produce an adequate definition of the geometric domain. For the redesign phase, a set of options were programmed into the inference mechanism. These rules focus on molding the geometric domain. Rules for the inference mechanism, and common databases were elaborated. The two-dimensional problems of a fillet in a tension bar, and a connecting link are used to illustrate the system. This is part of an ongoing project at the Center for Computer Aids for Industrial Productivity (CAIP) in New Jersey.
A Two Dimensional Rule-Based Shape Synthesis Method
Authors: Russell D. M. , Manoochehri S. P. 
Published: April 2021

Abstract
The objective of this study is to form two-dimensional structural/mechanical parts under general loading and restraint conditions. The designs created are of minimum weight with the stresses throughout the parts as close to the allowable limit as possible. The study uses a thresholding approach with minimal designer intervention for generating optimal configurations. The process begins with the user creating an initial design which encompasses all the specified loads and restraints. Finite element techniques are employed to discretize the part geometry. Then a set of heuristics are utilized for shape modification, by removing elements from the finite element model. A Bi-Directional Thresholding technique, BDT, is developed that determines which elements ought to be removed. After BDT is performed element connectivity is checked and maintained. A two-step connectivity check algorithm is implemented which locates and resolves major (complete) as well as minor (partial) losses in connectivity. This procedure, unlike most common shape optimization methods, is capable of quickly making very large changes in the geometry of the part. It is able to create holes in the geometry, where none existed in the initial shape, in order to produce a better design.
Multiobjective Optimization Dealing With Uncertainty
Authors: Mohandas S. U. , Sandgren E. 
Published: April 2021

Abstract
An algorithm to handle uncertainty in a multiobjective design optimization problem is developed. The procedure is applied to three examples where objective functions in each of them compete against each other. The uncertainty in the description of objective functions is modeled by using fuzzy goals and the terms of natural language. Multiobjective function is formulated as a fuzzy set. The minimization is carried out using a combination of the Complex Box method and a technique of ranking of fuzzy sets.
Application of Generalized Newton-Euler Equations and Recursive Projection Methods to Dynamics of Deformable Multibody Systems
Authors: Wehage R. A. , Shabana A. A. 
Published: April 2021

Abstract
A general symbolic-based method is presented for solving equations of motion for open-loop kinematic chains consisting of interconnected rigid and deformable bodies. The method utilizes matrix partitioning, recursive projection based on optimal block U-L factorization and generalized Newton-Euler equations to obtain an order n solution for the constrained equations of motion. Kinematic relationships between the absolute reference, joint and elastic coordinates are used with the generalized Newton-Euler equations for deformable bodies to obtain a large, loosely coupled system of equations. Taking advantage of the inertia matrix structure associated with elastic coordinates yields a recursive solution algorithm whose dimension is independent of the elastic degrees of freedom. The above solution techniques applied to this system of equations yield a much smaller operations count and can more effectively exploit vectorization and parallel processing. The algorithms presented in this paper are illustrated with the aid of cylindrical joints which are easily extended to revolute, prismatic, rigid and other joint types.
A Dynamics Workstation
Authors: Wu J. K. , Fogle M. A. , Wang J. Y. , Lu J. K. 
Published: April 2021

Abstract
The engineer’s modeling capability is the weakest link in the chain that supports the simulation of dynamic mechanical systems, due to the fact that engineers are forced to define mechanical system models in a way they are not familiar with. Advanced developments in computer techniques, computer graphics, and recursive computational algorithms for mechanical systems make the high speed dynamic simulation and graphic animation of mechanical systems feasible. But without a practical, useful modeling tool, the engineer has difficulty in using these advanced techniques.
The Dynamics Workstation is a modeling tool developed to help the engineer define mechanical system models in a natural, practical way. The engineer can communicate with the workstation naturally and interactively, define the model in formats that meet the needs for both high speed dynamic simulation and conventional dynamic analysis, define and assemble the model body by body using a relative coordinate system, visualize the configuration of the model, carry out simple joint exercises to detect the errors of the model in the early design stage, graphically lock and unlock joints, and adjust the system configuration even after initial assembly. The workstation automatically generates the mechanical system model based on the engineer’s interactive input data. The model design system strengthens the engineer’s modeling capability; it not only improves the design quality, but also boosts productivity.
Solution of Multibody Dynamics Using Natural Factors and Iterative Refinement: Part II — Closed Kinematic Loops
Authors: Wehage R. A. 
Published: April 2021

Abstract
A symbolic algorithm exploiting natural factors of generalized inertia matrices and iterative refinement to compute the dynamics of open kinematic-loop systems was developed in Part I of this paper. The general equations of motion for open and closed loop systems were derived in an earlier paper (Wehage, 1988) and it was shown that algorithms for open loop dynamics could be used to solve closed loop problems by cutting the secondary joints. In this paper it is shown that secondary joint forces can be obtained either from a dynamic force balance or from constraint surface deformations. Closed kinematic loops create additional numerical problems and require substantially more computational overhead. Therefore the iterative refinement algorithm developed in Part I is extended to address some of these problems. Exploitation of iterative refinement and computer architecture can substantially improve overall algorithm performance.
An Optimal Design of Composite Robot Arms
Authors: Sung C. K. , Shyl S. S. 
Published: April 2021

Abstract
A design methodology considering the issue of manufacturability, in particular, is presented for synthesizing high-performance articulating robotic systems fabricated with optimally-tailored composite laminates. By optimally specifying the types of fiber, matrix, stacking sequence, fiber volume fraction, fiber layups, etc., the synthesized composite material may possess significantly superior characteristics such as high damping, high stiffness, high strength and low mass.
In accordance with the design requirements, the minimum deflection during articulating motion or the fast settling time after the power stopped, the design objectives and constraint conditions were specified. As an illustrative example, a two-link robot manipulator fabricated with aforementioned composite laminates is employed for demonstrating the proposed design methodology.
Hydrodynamic Lubrication of Pocket Bearings and Effect of Contouring the Inner and Outer Regions, and Optimum Design Data
Authors: Bagci C. , McClure C. J. , Rajavenkateswaran S. K. 
Published: April 2021

Abstract
The article investigates pocket bearings with contoured profiles of exponential forms on both surfaces inside and outside of the step boundary forming hydro-dynamic action surfaces, and develops optimum design data yielding efficient slider bearings with small pockets with higher load capacities than conventional pocket bearings. In the case of a pocket bearings, in addition to the Reynolds equation used for the regions inside and outside the pocket, the continuity equation along the pocket boundary is satisfied to form the complete model of the bearing. The optimum design data includes dimensionless load-, flow-, temperature rise-, power loss-, stiffness-, and the coefficient of friction factors. Incompressible lubricant with temperature dependent viscosity is considered. Detailed study of conventional pocket bearings with planar surfaces is included. Some optimum exponential pocket bearings yield up to 561 percent increase in load capacity as compared to the conventional tapered bearings.
Direct Kinematics and Dynamics of a Planar Three-DOF Parallel Manipulator
Authors: Ma O. , Angeles J. 
Published: April 2021

Abstract
In this paper, the direct kinematics and dynamics, as applied to a three degree-of-freedom planar parallel manipulator, are studied. In the direct displacement problem, the method of virtual removal of kinematic constraints and a technique of four-bar linkage-performance evaluation are applied, so that the problem can be solved efficiently. Moreover, branches of solution may also be controlled in the numerical procedure without involving additional computations. In the dynamics formulation, the natural orthogonal complement is applied, which leads to the algorithmic-oriented equations of motion involving only independent generalized coordinates. A new and simple method is introduced to calculate the natural orthogonal complement and the joint-velocity Jacobian matrices. A fully solved numerical example of direct kinematics and dynamics is included.
A Manipulator Jacobian Based Modified Newton-Raphson Algorithm (JMNR) for Robot Inverse Kinematics
Authors: Singh V. K. , Gupta K. C. 
Published: April 2021

Abstract
This paper deals with the formulation of a manipulator Jacobian based Newton-Raphson algorithm for robot inverse kinematics. A strict descent feature has been incorporated into the algorithm to make it robust. Previous studies with Newton-Raphson type matrix iteration have produced an overdetermined system of linear equations which relates small changes in the joint variables. Dealing with these extra equations led to computational inefficiency. Previous manipulator Jacobian based predictor-corrector algorithms for inverse kinematics avoided this inefficiency, but these required either a variable time step or a small fixed time step; also special attention was required to start these algorithms. Motivated by the advantages of these two methods, this paper presents a robust manipulator Jacobian based Newton-Raphson algorithm for robot inverse kinematics.
History of the Larsen C Ice Shelf reconstructed from sub–ice shelf and offshore sediments
Authors: Smith J.A. , Hillenbrand C.-D. , Subt C. , Rosenheim B.E. , Frederichs T. , Ehrmann W. , Andersen T.J. , Wacker L. , Makinson K. , Anker P. , Venables E.J. , Nicholls K.W. 
Published: April 2021

Abstract
Because ice shelves respond to climatic forcing over a range of time scales, from years to millennia, an understanding of their long-term history is critically needed for predicting their future evolution. We present the first detailed reconstruction of the Larsen C Ice Shelf (LCIS), eastern Antarctic Peninsula (AP), based on data from sediment cores recovered from below and in front of the ice shelf. Sedimentologic and chronologic information reveals that the grounding line (GL) of an expanded AP ice sheet had started its retreat from the midshelf prior to 17.7 ± 0.53 calibrated (cal.) kyr B.P., with the calving line following ~6 k.y. later. The GL had reached the inner shelf as early as 9.83 ± 0.85 cal. kyr B.P. Since ca. 7.3 ka, the ice shelf has undergone two phases of retreat but without collapse, indicating that the climatic limit of LCIS stability was not breached during the Holocene. Future collapse of the LCIS would therefore confirm that the magnitudes of both ice loss along the eastern AP and underlying climatic forcing are unprecedented during the past 11.5 k.y.