bluuebunny/crossref_metadata_2025 huggingface dataset:
Transient Heat Transfer for Layered Ceramic Insulation and Stainless Foil Fire Barriers
Authors: Caplinger G. D. , Sutton W. H. , Spindler R. , Gohlke H.
Published: February 2008

Time-varying flame boundaries to heat transfer applications is a common application in energy and safety related systems. Many such systems could be tested and analyzed; however, the number of thermophysical parameters involved and the possibilities of boundary conditions are endless. Many papers have justified numerical and analytical models based on computational efficiency, with the objective of eventually applying those efficient techniques to real problems. There are, however, a number of standard test situations related to such systems that may be readily studied. The purpose of this study is to be able to optimize a coarse numerical model and range of thermophysical parameters that represent the physics of the real problem in a standard test situation. The applied thermal problem involves fire barrier safety in the design of buildings, such as hospitals and schools. Public buildings are often primarily constructed of concrete with significant gaps between sections to allow the concrete to expand and contract, due to climate changes or transients. In seismically active regions of the world, gaps may be up to several meters across, requiring some type of thermal fire barrier designed to prevent a fire from spreading for some time. A radiative/conductive fire barrier is first tested with an ASTM standard fire. A numerical model is then applied, which is an optimally coarse finite difference/finite volume formulation applied to the standard transient conduction energy equation with radiative heat flux (Ozisik, 1973) and to the radiative transfer equation (Su, 1993). The numerical model is able to predict thermal performance of the test system, illustrating the utility of the coarse grid model in engineering applications.
Pool Boiling Critical Heat Flux in Reduced Gravity
Authors: Shatto D. P. , Peterson G. P.
Published: February 2008

An experimental investigation has been conducted to measure pool boiling critical heat fluxes in reduced gravity. A horizontal cylindrical cartridge heater immersed in water at reduced pressures during parabolic flights on NASA’s KC-135 resulted in boiling on the heater surface. Visual observations and qualitative data trends indicate that the conventional Taylor-Helmholtz. instability model still governs the critical heat flux mechanism over the range of gravitational accelerations of the current study, which range from 0.0005 < g/go < 0.044. Using data from more than 40 individual tests, two semi-empirical correlations have been developed to account for the effect of thermocapillary flow, which tends to decrease the critical heat flux below the predictions of previous correlations.
Analysis of Coupled Nuclear/Thermal Instabilities of Two-Phase Flows in Parallel Boiling Channels
Authors: Uehiro M. , Rao Y. F. , Fukuda K.
Published: February 2008

An analytical model is proposed to study the two-phase flow instabilities of in-phase and out-of-phase modes in parallel boiling channels. This model takes into consideration the interaction between channels with different void fraction variations by modeling the diffusion of neutrons. Linear stability analysis in the frequency domain is performed to obtain stability boundaries and flow oscillation modes. In the case of parallel two channels, two types of stability boundaries are found to exist on the stability map; one for the instability of the in-phase mode and the other for that of the out-of-phase mode respectively. For a certain range of the void-reactivity coefficient, the void-reactivity feedback loop is found to be unstable in a certain region on the stability map, which has an effect on the stability of the in-phase mode. The interaction between channels affects the instability of the out-of-phase mode. The results are also obtained for the case of three and four channels. It is found that the channels having stronger interaction between them are more likely to oscillate in-phase with each other, while those having weaker interaction are more likely to oscillate out-of-phase with each other.
Heat Transfer Enhancement by Fins in the Microscale Regime
Authors: Chou F.-C. , Lukes J. R. , Tien C.-L.
Published: February 2008

The current literature contains many studies of microchannel and micro-pin-fin heat exchangers, but none of them consider the size effect on the thermal conductivity of channel and fin walls. The present study analyzes the effect of size (i.e., the microscale effect) on the microfin performance, particularly in the cryogenic regime where the microscale effect is often appreciable. The size effect reduces the thermal conductivity of microchannel and microfin walls and thus reduces the heat transfer rate. For this reason, heat transfer enhancement by microfins becomes even more important than for macroscale fins. The need for better understanding of heat transfer enhancement by microfins motivates the current study, which resolves three basic issues. First, it is found that the heat, flow choking can occur even in the case of simple plate fins or pin fins in the microscale regime, although choking is usually caused by the accommodation of a cluster of fins at the fin tip. Second, this paper shows that the use of micro-plate-fin arrays yields a higher heat transfer enhancement ratio than the use of the micro-pin-fin arrays due to the stronger reduction of thermal conductivity in micro-pin-fins. The third issue is how the size effect influences the fin thickness optimization. For convenience in design applications, an equation for the optimum fin thickness is established which generalizes the case without the size effect as first reported by Tuckerman and Pease.
Identification and Classification of Multi-Degree-of-Freedom and Multi-Loop Mechanisms
Authors: Liu Tyng , Yu Chung-Huang
Published: February 2008

This study concerns the degree-of-freedom, the arrangements of input and the type of mobility of multi-loop, multi-degree-of-freedom mechanisms. Firstly, “basic loops” are introduced, and a systematic scheme for identifying the actual degree-of-freedom of mechanisms is developed. The input, then, can be properly deployed, such that the mechanism has a totally constrained motion. Lastly, based on the input deployment, the mobility of mechanisms is classifed and identified into three types: total, partial and fractionated mobility. The procedure has been automated, and the atlas of all possible arrangements of input of up to eight-link planar mechanisms with only revolute joints is presented. The systematic method is helpful for the structural synthesis of multi-degree-of-freedom and multi-loop mechanisms, and for exploring their potential industrial applications.
A Topological Approach to the Dynamic Simulation of Articulated Machinery
Authors: Richard M. J. , Bindzi I. , Gosselin C. M.
Published: February 2008

This article presents a method for deriving the equations describing the motion of tree-structured mechanical systems of n rigid bodies linked to one another by spherical, universal and/or rotational joints. The dynamic and kinematic equations are formulated on the basis of the vector-network model. The vector-network approach is a mathematical model for the systematic development of nonlinear equations describing the motion of a system of rigid bodies interconnected by kinematic joints. The entire procedure of the vector-network is an application of the basic concepts of graph theory in which laws of dynamics have been integrated.
Automatic Determination of Feature Interactions in Design-for-Manufacturing Analysis
Authors: Gadh R. , Prinz F. B.
Published: February 2008

The current paper discusses a fundamentally new approach to defining and finding interactions in computer-aided design (CAD) forms or features. Feature classes are defined using a high-level abstract entity called a loop. Loops define features in a general manner and aid in the definition of feature boundaries as well. Interactions between features exist due to interactions between their boundaries. Several types of interactions are defined and automatically determined from the boundary representation solid model of the part subsequent to performing feature extraction.
Direct Kinematics in Analytical Form of the 6-4 Fully-Parallel Mechanism
Authors: Innocenti C.
Published: February 2008

This paper presents the direct position analysis of the fully-parallel mechanism that features six connection points on the base and four on the platform. The shape of both base and platform is general and, in particular, not restricted to being planar. The analysis is performed first by writing a suitable set of five closure equations in five unknowns. Then, by a specifically-developed elimination scheme, the closure equation set is reduced to a 32nd-order algebraic equation with only one unknown, which proves free from extraneous roots. Hence 32 closure configurations of the 6-4 mechanism do exist in the complex field. A numerical example is reported that confirms the new theoretical results.
Kinematic Structural Synthesis of Mechanisms Using Knowledge-Based Systems
Authors: Chew M. , Shen S. N. T. , Issa G. F.
Published: February 2008

This paper presents a knowledge-based systems approach to the automation of the conceptual synthesis of mechanisms. The system utilizes a procedure for synthesizing design alternatives based on the principle of separation of structure from function. This principle in turn resolves the problem of knowledge representation of design alternatives through the use of graph structures which are then evaluated using a set of heuristic rules. The expert system presented in this paper has been implemented and tested for the conceptual synthesis of variable-stroke engines and robot-hands kinematic structures. The system has shown the capability of producing numerous design alternatives for these two applications, and has provided consistent results based on the evaluation rules. It has also provided the designer with immediate feedback on the viability of any given design alternative and the reasons behind that decision.
Use of the Finite Element Method in the Analysis of Impact-Induced Longitudinal Waves in Constrained Elastic Systems
Authors: Gau W. H. , Shabana A. A.
Published: February 2008

In rotating elastic rods, dispersions occurs as the result of the finite rotations. By using Fourier method, it can be shown that the impact-induced longitudinal waves no longer travel with the same phase velocities. Furthermore, the speeds of the wave propagation are independent of the impact conditions including the value of the coefficient of restitution. In this investigation the use of the finite element method in the analysis of impact-induced longitudinal waves in rotating elastic rods is examined. The equations of motion are developed using the principle of virtual work in dynamics. Jump discontinuity in the system velocity vector as result of impact is predicted using the generalized impulse momentum equations. The solution obtained using the finite element method is compared with the solution obtained using Fourier method. Numerical results show that there is a good agreement between the solution obtained by using Fourier method and the finite element solution in the analysis of wave motion. However, discrepancies between the two solutions in the analysis of the velocity waves are observed and discussed in this paper.
The Geometry and Generation of NC Tool Paths
Authors: Sarma R. , Dutta D.
Published: February 2008

Numerically controlled milling is the primary method for generating complex die surfaces. These complex surfaces are generated by a milling cutter which removes material as it traces out pre-specified tool paths. The accuracy of tool paths directly affects the accuracy of the manufactured surface. The geometry and spacing of the tool paths impact the scallop height and time of manufacturing respectively. In this paper we propose a new method for generating NC tool paths. This method gives the part programmer direct control over the scallop height of the manufactured surface. The method also provides options to the part programmer for generating a variety of tool paths based on practical metrics such as tool path length, tool path curvature and number of tool retractions.
Exact Response Analysis and Dynamic Design of Cam-Follower Systems Using Laplace Transforms
Authors: Bagci C. , Kurnool S.
Published: February 2008

This article presents Laplace transforms utilizing methods to determine response of follower systems to motions machined on cams. The exact response of a follower system at any cycle, at any time, or in any time zone is directly determined without the need for numerical integrations. The method permits the study of response for many cycles to determine beat effect, the critical cam speeds, and possible follower jump conditions. Cam profile is corrected to eliminate static error and oscillate follower about exact position. Disk cams with translating roller followers with one and two degrees of freedom are considered in the article. Numerical illustrations are included, where results by other numerical methods (matrix exponential and phase plane-6) are compared.
Synthesis and Steady-State Analysis of High-Speed Elastic Cam-Actuated Linkages With Fluctuated Speeds by a Finite Element Method
Authors: Liu Hsin-Ting J.
Published: February 2008

A cam driving a lumped inertia through an elastic slider-crank follower linkage with its actuator, a D. C. motor, has been considered in this work. An iterative procedure utilizing the finite element method developed by Midha et al. (1978) is used to synthesize the cam profile to produce a desired output motion at a given design speed and damping ratio. The elastic deflections induced by the large inertia of the linkage operating at a fluctuated high speed of the driving cam are taken into account in synthesizing the cam profile. Responses of the synthesized linkages are simulated and found to be satisfactory at the design conditions.
Synthesis and Workspace Study of Endoscopic Extenders With Flexible Stem
Authors: Faraz A. , Payandeh S.
Published: February 2008

Endoscopic surgery is a less invasive method of surgery as compared to open surgery. However, indirect vision, limited hand movement and lack of haptic sensation, combined with the tiring posture of holding long tools makes it a very difficult task for the surgeon to perform (Tendick, 93; Faraz, June, 95). Consequently, the surgeon has a fraction of the dexterity and sensing of that of open surgery. This is specially the case in laparoscopic surgery which is a specific branch of endoscopic surgery, and is performed on the abdomen. The dexterity problem associated with laparoscopic surgery arises from the fact that the present rigid stem extenders can approach the surgical site with some fix orientation (determined by the connecting line between the position of surgical site and the port of entry). Lack of 2 DOF at the stem, to orient the tool’s tip to the desired orientation near the surgical site, prevents the surgeon from having the required dexterity and agility. By adding revolute/spherical joints on the stem, the required internal capability in orienting the tool can be achieved, and hence provide more dexterity for the surgeon. Although, there has been some publication in the literature about different design possibilities (e.g., Rinninsland, 93; Melzer, 93; Neisius, 94), as well as U.S. patents (Matsumaru, 92; Heimberger, 94), they are all dealing with special designs with specific design focus. There is a lack of general study of flexible endoscopic extenders with wider design objectives. For example, such objectives can be: (a) general type synthesis of the joint design, (b) formulation of workspace requirements of laparoscopic extenders, and (c) comparative study of different designs in search of the optimal design(s). The objective of this report is to have a systematic synthesis of the joints, as well as formulate the dexterous workspace for laparoscopic extenders with flexible stem, in order to find the optimum design.
Notes on Screw Product Operations in the Formulations of Successive Finite Displacements
Authors: Huang C.
Published: February 2008

Geometrical interpretations of two line-based formulations of successive finite displacements, Dimentberg’s formulation and a linear formulation, are discussed in this paper. The interpretations are based on the fact that the pitch of the screw product of two unit line vectors is consistent with Parkin’s definition of pitch. Finite twists in Dimentberg’s formulation are shown to be the screw product of unit line vectors divided by the scalar product of unit line vectors. On the other hand, Finite twists in the linear formulation are interpreted as the screw product of unit line vectors divided by the scalar product of direction-cosine vectors.
Effects of Planetary Speed-Reduction Ratio on Mean Service Life
Authors: Savage M. , Rubadeux K. L. , Coe H. H.
Published: February 2008

Planetary-gear transmissions are compact speed reductions which use parallel-load paths to transmit high power. The range of possible reduction ratios is bounded from below and above by limits on the relative size of the planet gears. For a single-plane planetary transmission, the speed-reduction ratio must be greater than two for planet gears to exist. As the ratio increases, so does the size of the planets relative to the sizes of the sun and ring. Which ratio is best for a planetary reduction can be resolved by studying a series of optimal designs. In this series, each design is obtained by maximizing the service life for a spur-gear planetary with a fixed size, speed-reduction ratio, input speed, power and materials. The planetary-gear reduction service life is modeled as a function of the two-parameter Weibull distributed service lives of the ball bearings and spur gears in the reduction. Planet-bearing life strongly influences the optimal reduction lives which point to an optimal planetary reduction ratio in the neighborhood of four to five.
A New Class of Six-Bar Mechanisms With Symmetrical Coupler Curves
Authors: Shieh W.-B. , Tsai L.-W. , Azarm S. , Tits A. L.
Published: February 2008

A new class of six-bar mechanisms with symmetrical coupler-point curves is presented. This class of mechanisms is made up of a four-bar linkage with an additional dyad to form an embedded skew pantograph. Because the coupler curve generated at an output point is amplified from that of a four-bar, a compact mechanism with a relatively large coupler curve can be obtained. In addition, due to their structure arrangement, the analysis and synthesis of such mechanisms can be easily achieved. Finally, an example mechanism from this class is illustrated and compared with a four-bar linkage with the same coupler curve.
Fine Tuning of Rational B-Spline Motions
Authors: Srinivasan L. N. , Ge Q. Jeffrey
Published: February 2008

This paper presents two algorithms for fine-tuning rational B-spline motions suitable for Computer Aided Design. The problem of fine-tuning of rational motions is studied as that of fine-tuning rational curves in a projective dual three-space, called the image curves. The path-smoothing algorithm automatically detects and smoothes out the third order geometric discontinuities in the path of a cubic rational B-spline image curve. The speed-smoothing algorithm uses a quintic rational spline image curve to obtain a second-order geometric approximation of the path of a cubic rational B-spline image curve while allowing specification of the speed and the rate of change of speed at the key points to obtain a near constant kinetic energy parameterization. The results have applications in Cartesian trajectory planning in robotics, spatial navigation in visualization and virtual reality systems, as well as mechanical system simulation.
Polygon-to-Object Boundary Clipping in Object Space for Hidden Surface Removal in Computer-Aided Design
Authors: Chieng Wei-Hua , Hoeltzel D. A.
Published: February 2008

Since techniques for both polygon-to-polygon clipping and polygon-to-object boundary (contour) clipping have been developed, it appears that the visibility problem may exhibit potential for improvement in its time complexity. This paper provides some insight and results concerning the performance of an object-space hidden surface removal algorithm based on polygon-to-object boundary (contour) clipping. The applicability of these results to the graphic rendering of partially visible objects in an incremental computer-aided geometric design system, such as that used in mechanical design, is demonstrated. The polygon-to-object boundary clipping algorithm is compared with the more conventional polygon-to-polygon approach to clipping for hidden surface removal. Examples are included which demonstrate the potential for improving the performance of software-based hidden surface removal algorithms used in computer-aided geometric design applications.
Design of a Vernier Punch and Die Set for Single-Minute Bending Set-Ups
Authors: Sturges R. H.
Published: February 2008

An opportunity is found to reduce set-up time in sheet metal panel bending tasks by deliberately leaving gaps between a segmented punch to allow passage of a bent flange or to adjust the distance between articulated die sections for re-entrant bends. The effects of this practice on part appearance and dimension is addressed to assure part quality. Unconstrained bending in the gap area is modelled, and the gap/thickness ratio is found to be an indicator of part geometry and subjective quality. A zero set-up punch and die set is described for 4-bend parts.
On Global Feasible Search for Global Design Optimization with Application to Generalized Polynomial Models
Authors: Lo Chihsiung , Papalambros P. Y.
Published: February 2008

A key idea for deterministic global optimization is the use of global feasible search, namely, algorithms that guarantee finding feasible solutions of nonconvex problems or prove that none exists. In this article, a set of conditions for global feasible search algorithms is established. The utility of these conditions is demonstrated on two algorithms that solve special problem classes globally. Also, a new model transformation is shown to convert a generalized polynomial problem into one of the special classes above. A flywheel design example illustrates the approach. A sequel article provides further computational details and design examples.
Infeasibility and Non-Optimality Tests for Solution Space Reduction in Discrete Optimal Design
Authors: Pomrehn L. P. , Papalambros P. Y.
Published: February 2008

Techniques employed for nonlinear design optimization with discrete variables are studied in the context of a particular problem arising from the design of a gear train. The mathematical model formulation was presented in an earlier article. In this sequel, a solution derivation is described, patterned as a multistage process. After certain reformulation and relaxation, a variety of infeasibility and non-optimality tests are performed, greatly reducing the size of the space containing the global optimum. Methods used to investigate the remaining space do not guarantee a global optimum, but could be replaced by more costly methods that do provide such guarantees. A global infimum is generated, bounding any improvements on the best known solution.
Limits at $3 in a New Formulation for Path-Placement in the Workcells of Planar 3-R Robots
Authors: Davidson J. K. , Soman N. A.
Published: February 2008

Excursion-limits at the third joint of a three-hinged planar robot are incorporated into a new systematic formulation for path-placement in which the three-dimensional solution-space is decomposed into a two-dimensional space of variables that strongly control the placement of the path and a one-dimensional space that is much less critical. The new formulation determines all acceptable positions for the first joint of the robot relative to the workpiece. All possible acceptable designs appear in a graphical form that can be readily visualized and be directly measured in a Cartesian frame of reference in the workcell. The method is extended to closed tool-paths, and the method is illustrated with practical examples.
The Linear Representation of the Screw Triangle—A Unification of Finite and Infinitesimal Kinematics
Authors: Huang Chintien , Chen Chien-Ming
Published: February 2008

This paper presents the linear representation of the screw triangle. The resultant twist of two finite twists is shown to be a linear combination of five screws. The linear representations of all degenerate screw triangles are also derived. The limiting cases of these results of finite displacements confirm the theory of screws in infinitesimal kinematics. The finite kinematic analysis of multi-link serial chains is performed by using the linear representation of the screw triangle to demonstrate a unification of finite and infinitesimal kinematics.
Detection of Isomorphism Among Kinematic Chains Using the Distance Concept
Authors: Yadav J. N. , Pratap C. R. , Agrawal V. P.
Published: February 2008

A new matrix, called the joint-joint relation matrix, is defined for representing the structure of a kinematic chain. An algorithm has been developed for deriving the joint-joint distance matrix of a kinematic chain from its joint-joint relation matrix with the help of the computer. A new structural invariant, called the Arranged Sequence of Total Distance Ranks of all the Joints, and based on the concept of distance, has been developed for a kinematic chain, leading to the development of a simple methodology for detecting isomorphism among planar kinematic chains with simple joints.
An Investigation of Techniques for Asymmetry Rectification
Authors: Kulkarni P. , Dutta D.
Published: February 2008

This paper is concerned with symmetry and asymmetry in objects. Earlier studies on the subject have dealt with the detection of symmetry. We study the problem of asymmetry rectification, i.e., given an asymmetric profile, suggest geometric changes to make it symmetric. We have investigated two techniques for asymmetry rectification. This paper reports on the techniques and the results. First, we analyze the problem using skeleton representations and propose a simple algorithm for rectifying asymmetric convex profiles. Next, we outline an optimization scheme for the rectification of convex and nonconvex profiles, in 2D and 3D. Implemented examples are presented for both algorithms.
Using Pade´ Approximants and Curve-fitting to Approximate Eigenvalues and Eigenvectors for Large Design Changes
Authors: Vance J. M. , Bernard J. E.
Published: February 2008

Our overall goal is to develop software that facilitates the interactive participation of the designer in the optimization process. We are focusing this research on problems which use finite element solutions as part of the objective function. One challenge to implementing interactive participation in these types of problems is the high computational burden of computing a finite element solution for each design change. The research presented here focuses on a unique method to develop fast approximations for natural frequencies and mode shapes which can be used to avoid the time-consuming re-solution process and which will facilitate interactive design for systems with even large design changes.
Computer-Aided Design With Spatial Rational B-Spline Motions
Authors: Ju¨ttler B. , Wagner M. G.
Published: February 2008

Using rational motions it is possible to apply many fundamental B-spline techniques to the design of motions. The present paper summarizes the basic theory of rational motions and introduces a linear control structure for piecewise rational motions suitable for geometry processing. Moreover it provides algorithms for the calculation of the surface which is swept out by a moving polyhedron and examines interpolation techniques. The methods presented in this paper can be applied to various problems in computer animation as well as in robotics.
Classification of Serial Robot-Manipulators with Nonremovable Singularities
Authors: Karger A.
Published: February 2008

In this paper we discuss singular configurations of serial robot-manipulators with respect to their removability. A removable singularity is a singularity which can be removed from a motion of the end-effector by a small change of the motion. The most interesting situation appears for robot-manipulators with 5 degrees of freedom, because the case of 4 degrees of freedom is easy and singular configurations of robot-manipulators with 6 degrees of freedom are nonremovable. In the paper we give the complete list of all 5R robot-manipulators which have nonremovable singularities. The image of the singular set in the parameter space for such manipulators can be a plane, a quadric, a cylinder or an algebraic surface of degree 3 or 7. All of them are explicitly given.
Geometry and Pressure in a Trochoidal-Type Machine Without Apex Seal
Authors: Li Shuangqing , Shung J. B.
Published: February 2008

In a trochoidal-type machine, the friction and wear due to the apex seal is a major problem. In order to increase the efficiency and reliability of this type of machine, we propose to replace the apex seals by tight running clearances. A peritrochoid with its special conjugate envelope is a good candidate for a trochoidal-type machine without apex seal. This paper presents its geometry attributes and pressure processes inside the pockets. First, the coordinates of contact point and pocket volumes at any shaft angle are derived. Then, the pressure processes inside the pockets are simulated with simplified valves. Finally, the effect of clearance on pocket pressure at different speeds is studied. The results indicate that a trochoidal-type machine without apex seal is worthy of further research and development.
Belt Number Factor in Multiple V-Belt Drives
Authors: Gerbert G. , de Mare´ J.
Published: February 2008

Tolerances on belts and pulleys lead to a nonuniform tension distribution among the belts in a multiple belt drive. Material imperfections lead to a service life distribution. Both phenomena contributes to the life of the drive i.e. the shortest life of any of the belts. To compensate for life reduction a belt number factor is introduced. The combined effect of tension and life distributions is simulated and compared with analyses. It appears that life distribution is the major contributor. Practical values of the belt number factor are presented.
Branch Identification of Geared Five-Bar Chains
Authors: Dou Xiaohong , Ting Kwun-Long
Published: February 2008

This paper presents the method to identify the rotatability and branch condition in linkages containing simple geared five-bar chains. The method is subsequently extended to identify the existence of dead positions. When used in the computer aided linkage synthesis, the algorithm may effectively reduce the complexity of the finite position synthesis of geared five-bar linkages to the level similar to that of four-bar linkages. The algorithm is effective for any linkage inversion, any type of synthesis problem, any input condition, and any number of discrete positions. The method can be generalized to other serially connected multiloop linkages.
A Study of the Solvability of the Position Problem for Multi-Circuit Mechanisms by Way of Example of the Double Butterfly Linkage
Authors: Waldron K. J. , Sreenivasan S. V.
Published: February 2008

It is frequently forgotten that the common methods of position analysis of planar linkages, which are based on dyadic decomposition, are not general. This is true regardless of whether a graphical or analytical approach is used. It is demonstrated in this paper that relatively simple linkages can give rise to problems that cannot be addressed by dyadic decomposition methods, and that solution of these problems can be far more complex.
Successive Optimal Design Procedure Applied on Conventional Fuel Injection Equipment
Authors: Kegl B.
Published: February 2008

The paper describes a procedure of solving an optimal design problem with continuous/discrete design variables. The procedure is applied to a set of design parameters of a conventional fuel injection equipment for a diesel engine. The design parameters concern the design of the cam, high pressure pump, delivery valve, snubber valve, high pressure tube and injector. By the proposed procedure the continuous/discrete optimal design problem is replaced by a finite sequence of auxiliary problems where all design variables are treated as continuous. After solving each auxiliary problem one of the discrete design variables is set equal to the closest available discrete value and eliminated from the set of design variables. This process does not guarantee that an optimal solution to the continuous/integer programming problem is located; however it does produce improved near optimal designs for conventional fuel injection equipment. The proposed procedure is illustrated with a numerical example.
The Design of Cam, Steel-Strip Function Mechanism
Authors: Qimi Jiang , Ji Zhou
Published: February 2008

In this paper, a kind of cam, steel-strip function mechanism is presented. This mechanism can realize variable transmission ratio between two parallel axes. Its merit is that there is no return error of transmission. The general designing method of this kind of mechanism is presented in detail in this paper.
Finite Element and Experimental Studies of Creep at the Interface of Press Fitted Gears-Shafts Connections
Authors: Okamoto N. , Tanaka N. , Nogami M.
Published: February 2008

It is shown experimentally that relative movement of shrink-fit connections occurs on mating surfaces even if the transmitting torque does not exceed the static frictional torque. However, there is a transmitting torque threshold below which no relative movement occurs. The experimental thresholds agree well with predictions from theoretical calculations of the slip model, which is based on the numerical results of shear stress variation along the interface and on Coulomb’s law of friction.
Experimental Study of a Variable Pressure Damper on an Automotive Valve Train
Authors: Liou Jin Jang , Huang Grodrue , Hsu Wensyang
Published: February 2008

A variable pressure damper (VPD) is proposed here to adjusted the friction force on the valve spring to investigate the relation between the friction force and the valve train. Valve bounce, component separation, spring vibration are observed in the testing. The VPD is shown to have significant improvement in reducing valve bouncing distance and surge vibration under 2985 rpm. Also, experimental results indicate that the component separation becomes more imminent at high speeds with larger damping forces. Here, in certain speed range, a proper frictional force provided by VPD is shown to be able to eliminate bouncing completely without causing component separation.
Tooth Surface Measurement of Conical Involute Gears by CNC Gear-Measuring Machine
Authors: Mitome Ken-ichi , Gotou Tohru , Ueda Takeshi
Published: February 2008

Developed is a new tooth surface measurement of conical involute gears by CNC gear-measuring machines. Advances in the design and production of conical involute gears and its wide applications are demanding the measurement of the conical involute gears using CNC gear measuring machines. Therefore, a new concept called an “equivalent helical gear” is introduced. Thus, a conical involute gear can be measured as a helical involute gear. Experiments demonstrate that this new method gives accurate results and has practical value. Finally tooth surface analysis of a conical involute gears is also presented.
Plane Stress Analysis of End-Loaded Orthotropic Curved Beams of Constant Thickness With Applications to Full Rings
Authors: Tutuncu N.
Published: February 2008

Plane elasticity solutions using stress functions for stresses and displacements in orthotropic curved beams subjected to end moment and force loadings are presented. Applications to curved beams with straight portions and full rings are considered. The results are compared with the isotropic case. Two parameters, which essentially measure the degree of anisotropy, each pertaining to a different loading state are defined and their effects on the stress and displacement distributions are discussed. It has been shown that increasing these parameters reduced the stresses in the members.
Center-point Curves Through Six Arbitrary Points
Authors: Murray A. P. , McCarthy J. Michael
Published: February 2008

A circular cubic curve called a center-point curve is central to kinematic synthesis of a planar 4R linkage that moves a rigid body through four specified planar positions. In this paper, we show the set of circle-point curves is a non-linear subset of the set of circular cubics. In general, seven arbitrary points define a circular cubic curve; in contrast, we find that a center-point curve is defined by six arbitrary points. Furthermore, as many as three different center-point curves may pass through these six points. Having defined the curve without identifying any positions, we then show how to determine sets of four positions that generate the given center-point curve.
Assembly Configurations of Single-Loop Mechanisms With Pin Joints and Sliding Joints
Authors: Foster D. E. , Cipra R. J.
Published: February 2008

This paper examines the problem of enumerating the assembly configurations (ACs), also called circuits, of planar mechanisms which can be described as a single loop. A method is given which allows the user to find and distinguish the ACs of such a mechanism, by determining if each pair of adjacent links can line up. If each pair can line up, then the mechanism has one AC; otherwise, it has two ACs. It is shown that a single-loop mechanism can have no more than two ACs. The method is demonstrated with two examples.
A Simple and Accurate Method for Determining Large Deflections in Compliant Mechanisms Subjected to End Forces and Moments
Authors: Saxena A. , Kramer S. N.
Published: February 2008

Compliant members in flexible link mechanisms undergo large deflections when subjected to external loads. Because of this fact, traditional methods of deflection analysis do not apply. Since the nonlinearities introduced by these large deflections make the system comprising such members difficult to solve, parametric deflection approximations are deemed helpful in the analysis and synthesis of compliant mechanisms. This is accomplished by representing the compliant mechanism as a pseudo-rigid-body model. A wealth of analysis and synthesis techniques available for rigid-body mechanisms thus become amenable to the design of compliant mechanisms. In this paper, a pseudo-rigid-body model is developed and solved for the tip deflection of flexible beams for combined end loads. A numerical integration technique using quadrature formulae has been employed to solve the large deflection Bernoulli-Euler beam equation for the tip deflection. Implementation of this scheme is simpler than the elliptic integral formulation and provides very accurate results. An example for the synthesis of a compliant mechanism using the proposed model is also presented.
Identification of the Machine Settings of Real Hypoid Gear Tooth Surfaces
Authors: Gosselin C. , Nonaka T. , Shiono Y. , Kubo A. , Tatsuno T.
Published: February 2008

In the spiral bevel and hypoid gear manufacturing industry, master gear sets are usually developed from initial machine settings obtained from computer software or instruction sheets. These initial machine settings are then modified until a satisfactory bearing pattern is obtained, a process called bearing pattern development. Once a satisfactory bearing pattern is obtained, manufacturing errors and heat treatment distorsions can be accounted for by proportionally changing the machine settings according to the results of a V-H test in which the pinion vertical and horizontal positions are modified until the bearing pattern is acceptable. Once a satisfactory combination of master pinion and gear is obtained, their actual tooth surfaces usually do not correspond to those of the initial theoretical model, and the theoretical pinion and gear surface definitions are unknown. This paper presents a computer algorithm used to identify the machine settings producing a theoretical tooth surface closest to that of a measured surface, what the authors call Surface Match, in order to effectively simulate the kinematical behavior of real gear teeth. The approach is applicable to both 1st and 2nd order surface errors, including profile deviation, for any cutting process. However, given the availability of experimental data for the Fixed Setting™, Formate™ and Helixform™ cutting processes, the examples presented in the paper are related to these cutting processes.
Simulation of Nonlinear Dynamics of Liquid Filled Fuel Tanker Shell Structure Subjected to Rollover Collision With Validation
Authors: Park S. U. , Gilmore B. J. , Singer R. R.
Published: February 2008

The transport of hazardous materials in truck cargo tanks can cause severe environmental damage as a result of the tank’s failure during a collision. Impact due to collision involves the transient dynamic response of the tank, fluid and their interaction. This paper develops a design oriented computational approach to predict the dynamic transient response of the tank shell structure subjected to impact loads during crash accidents. In order to compute the fluid and structural interaction, the finite element formulations for the added mass to the structure are developed and integrated with DYNA3D, a nonlinear dynamic structural finite element code, and they are validated by pendulum impact experiment. This paper presents the lumping process required by the added mass approach for cargo tanks under impact conditions. Thus, due to its efficiency the computer based approach provides a design tool for fluid filled thin walled structures in general and cargo tanks subjected to an impact situation. The structural performance of cargo tank shell construction is investigated. This research will contribute to improvement in design, modeling, and analysis techniques for crashworthiness and integrity of liquid mechanical structure systems which are subjected to impulsive loads like those found in vehicle collisions.
Applying Virtual Reality Techniques to Sensitivity-Based Structural Shape Design
Authors: Yeh T. P. , Vance J. M.
Published: February 2008

Virtual reality (VR) provides a design space consisting of three-dimensional computer images where participants can interact with these images using natural human motions in real time. In the field of engineering design, prototyping and design verification have provided the initial application areas for VR. The research presented in this paper takes the scenario one step further by incorporating free-form deformation techniques and sensitivity analysis into the virtual world such that the designer can easily implement analysis-based shape design of a structural system where stress considerations are important. NURBS-based free-form deformation (NFFD) methods and direct manipulation techniques are used as the interface between the VR interaction and the finite element model. Sensitivity analysis is used to allow the designer to change the design model and immediately view the effects without performing a re-analysis. An engine connecting rod is analyzed to demonstrate how virtual reality techniques can be applied to structural shape design.
Stack-Up Forces for Normal and Abnormal Operating Conditions in a Railroad Roller Bearing Assembly
Authors: Wang H. , Conry T. F. , Cusano C.
Published: February 2008

Stack-up force distributions are obtained for normal and abnormal operating conditions in a class F (6 1/2 × 12) railroad tapered roller bearing-axle assembly for various friction coefficients, press-fits and cap screw preloads. Three conditions that affect the stack-up force distribution are considered: a steady-state normal-operating temperature distribution, a steady-state temperature distribution resulting from a stuck brake or a jammed outboard roller, and a transient temperature distribution due to multiple jammed outboard rollers. The steady-state normal or abnormal operating temperature have insignificant effects for nominal values of interference, friction and cap screw preload. However, the effect of the transient temperature due to multiple jammed outboard rollers on the stack-up system is detrimental due to localized high temperature gradients near the outboard cone area and a distortion of the original surface geometry of the cone.
Interference Impact Analysis of Multibody Systems
Authors: Wang D. , Conti C. , Beale D.
Published: February 2008

A new computer aided analysis method for frictionless impact problems due to interference between two bodies in a constrained multibody system is presented in this paper. A virtual contact joint concept is used to detect interference between two bodies and calculate the jump in the body momenta, velocity discontinuities and rebounds. The interference surfaces can be described by the joint coordinates of the virtual contact joint, which are very useful for determining the impact time, the types and positions of two impact surfaces and impact initial conditions when an interference happens between two bodies.
Optimal Design of a Medical Staple Using Shape Memory Alloy
Authors: Lin Y. , Huang M. , Zhang M.
Published: February 2008

This paper presents the mechanical design of a medical staple using shape memory alloy (SMA) material. The design problem was formulated as an optimization problem minimizing an energy functional. The constraints were the length of wire, the properties of the SMA material, and the required clamping force. The Euler-Lagrange equation of this isoperimetric calculus of variation problem was derived, which was a fourth order two-point boundary value problem. An analytical solution was constructed and verified. A numerical optimization technique was applied to generate other possible solutions for the boundary value problem. The objective was to minimize the error of the solution for specific boundary conditions. The sequential quadratic programming algorithm was applied with Runge-Kutta integration to solve the boundary value problem. The design procedure described in this paper could be applied to the design of other mechanical components of wire form using SMA material.
A Probabilistic-Based Design Model for Achieving Flexibility in Design
Authors: Chen W. , Yuan C.
Published: February 2008

In this paper we propose the use of a probabilistic-based design model as a basis for providing the flexibility in a design process that allows designs to be readily adapted to changing conditions. Our proposed approach can be used to develop a range of solutions that meet a ranged set of design requirements. Meanwhile, designers are allowed to specify the varying degree of desirability of a ranged set of design performance based on their preferences. The Design Preference Index (DPI) is introduced as a design metric to measure the goodness of flexible designs. Providing the foundation to our work are the probabilistic representations of design performance, the application of the robust design concept, and the utilization of the compromise Decision Support Problem (DSP) as a multiobjective decision model. A two-bar structural design is used as an example to demonstrate our approach. Our focus in this paper is on introducing the probabilistic-based design model and not on the results of the example problem, per se.