bluuebunny/crossref_metadata_2025_split huggingface dataset:
Discussion of the Forces Acting in Tension Impact Tests of Materials
Authors: Clark D. S. , Duwez P. E. 
Published: March 2021

Abstract
A method of measuring the forces acting on a specimen during a tension impact test is described briefly in this paper. In this method a dynamometer is used in tests made in a rotary impact testing machine in which impact velocities up to approximately 200 fps can be attained. The method of computing force-time relations prevailing in a specimen subjected to tension impact is described from the standpoint of the theory of the propagation of elastic and plastic strain. The method is applied to a specific material to illustrate the computing procedure. A theoretical stress-time diagram has been computed for a specimen of SAE 1020 cold-rolled steel 0.300 in. diam and 8 in. long for an impact velocity of 150 fps. This computation has been made (a) on the basis that the dynamometer is rigid, and (b) on the basis of a dynamometer mounted in a manner approximately equivalent to that in the actual equipment. The diagrams are for the stress-time relations at the fixed end of the specimen. The computed curves are compared with an experimental force-time diagram obtained on the same material. The general shape of the experimental diagram is quite similar to the theoretical diagram computed on the basis of a nonrigid dynamometer.
The Influence of the Dimensional Factors on the Mode of Yielding and Fracture in Medium-Carbon Steel—I: The Geometry and Size of the Flat Tensile Bar
Authors: Miklowitz Julius 
Published: March 2021

Abstract
A detailed study of the local principal strains, during uniform straining in a flat tension bar, has proved valuable in explaining the observed large variations of the local necking strains, with uniform changes in geometry and size of the bar. An analogy has been brought out between the restraining action of the bar heads on the gage material, and that of the stagnant material of the neck on the flowing material adjacent to it. In both cases the magnitude of the restraining dimension is important, the degree of restraint increasing with an increase in dimension. The study in deformation is presented for both uniform straining and the complicated crosslike neck at fracture. The maximum strains in the neck increased when the bar size decreased. The maximum strain, in the lateral direction parallel to the bar width, became less, as the width-to-thickness ratio of the bar increased from 1 to 7. Beyond this value, no effects were noted. The axial strain, calculated from the two lateral strains, reflected their trends.
Plastic Deformation of a Circular Diaphragm Under Pressure
Authors: Gleyzal A. 
Published: March 2021

Abstract
In this report a numerical solution is given of a set of equations consisting essentially of three plasticity laws, two strain-displacement laws, and two equilibrium laws which describe the action of a clamped, thin, circular diaphragm as it yields plastically when pressure is applied to one side. The stresses, strains, thickness variation, and deflections for any thin circular diaphragm of a given material may be computed by the numerical integration of the equilibrium conditions, the geometric conditions relating displacements and strains, and the stress-strain laws. The solution may be reduced to the solution of a second-order differential equation with the radial distance r as independent variable. The solution depends upon an experimentally determined function, τ (γ), which describes the stress-strain properties of the material, and upon three parameters, the pressure p, the original thickness h0, and the radius a of the clamping ring. It is found that for a given material, a family of curves with pa/h0 as a parameter serves to predict the solution for any thin circular diaphragm of the same material. This analysis has been carried out for a particular function τ(γ) based upon results of a tensile test made on a specimen of medium steel. Graphs of theoretically and experimentally determined values of deflection, radial and circumferential strains, radial and circumferential stresses, and thickness corresponding to various pressures are presented which apply to all diaphragms made of the same steel as this specimen.
Contact Stresses in the Rolling of Metals—1
Authors: MacGregor C. W. , Palme R. B. 
Published: March 2021

Abstract
Special equipment is described which was designed and constructed to investigate the distributions of the normal pressures and the longitudinal and transverse shearing stresses along the arc of contact during the rolling of metals between plain cylindrical rolls. While the paper is restricted to a description of this apparatus, it is planned to utilize it in studying the effects of many of the important rolling variables both on the contact stresses and on the resulting mechanical properties of the rolled product. Experimental results will be presented in a later paper.
Flow of a Compressible Fluid Through a Series of Identical Orifices
Authors: Robinson C. S. L. 
Published: March 2021

Abstract
This paper contains a method for computing the weight flow of a gas or vapor through a number of like orifices. It is based upon the general equation for a single orifice and upon certain reasonable assumptions. There are included curves showing the influence of the number of orifices. For expansions beyond the over-all critical-pressure ratio, the effect of each additional orifice is increasingly reduced. For example, increasing the number of like orifices from 6 to 7 will decrease the flow only about 5 per cent. Two applications of this study are suggested, i.e., to multiple-orifice devices for heat-exchange equipment, and to labyrinth packing for shaft seals.
Long-Term Performance Assessment of Swell Packers Under Different Oilfield Conditions
Authors: Qamar Sayyad Zahid , Pervez Tasneem , Akhtar Maaz , Kharusi Moosa Al 
Published: March 2021

AbstractSwelling elastomer seals and packers provide effective zonal isolation in difficult oil and gas fields, resulting in significant savings in rig time and development expenses. Companies involved in petroleum engineering applications provide no information about the longevity or endurance of swelling elastomer packers when exposed to different conditions in the well. This paper describes the design and construction of a test facility for long-term performance assessment of actual full-scale water and oil-swell packers, and the results of the 5-year study. The ten packers are made of three types of swelling elastomers, are kept in crude oil and saline solutions at room and high temperatures, and are exposed to varying high pressures. Regular logs of readings were maintained over the whole study period. Earlier sealing was observed in elastomers immersed in low-salinity water and subjected to high temperature. Rate of swelling was higher in water-based elastomers than in oil-based seals. One packer never sealed completely. Pressurized tubes either retained sealing the whole time or re-sealed after removing of pressure or reducing it to a lower value. Results for the fast-swell and medium-swell elastomer, low- and high-salinity water and crude oil, and low- and high-operating temperatures were mostly in line with short-term tests on laboratory samples published earlier. This unique longevity assessment study can be used by drilling engineers and developers in assessing the suitability of swelling elastomers for target fields and in improving the design of swell packers.
Applying a Theta-Krill Herd Algorithm to Energy Management of a Microgrid Considering Renewable Energies and Varying Weather Conditions
Authors: Aldosary Abdallah , Rawa Muhyaddin , Ali Ziad M. , Abusorrah Abdullah , Rezvani Alireza , Suzuki Kengo 
Published: March 2021

Abstract
Recently, researchers have shown an increased interest in using renewable-based distributed generations (DGs) in microgrids (MGs). Therefore, the economic operation of MGs plays a vital role in reducing total daily costs and greenhouse gas emissions in the modern power system. This study presents a day-ahead optimization management for a grid-tied MG supplied by small-scale renewable energy sources (RESs) like photovoltaic (PV) systems. The major aim of the suggested optimal energy management system is to minimize the cost of RERs and storage facilities in the MG for power generation while satisfying technical constraints. In addition, an improved mathematical model is suggested for the PV power generation using real data for four dissimilar days. To attain accurate results, uncertainties in the generations, load demand, and market price are probabilistically modeled. To handle the optimization problem, the θ-modified krill herd (θ-MKH) algorithm is used. The suggested algorithm for solving the optimization problem is investigated on numerical examples with different RESs and storages in the MG and compared with conventional approaches. The results attained illustrate that the recommended algorithm can utilize the cheapest sources while covering technical constraints.
An Automated Machine Learning-Genetic Algorithm Framework With Active Learning for Design Optimization
Authors: Owoyele Opeoluwa , Pal Pinaki , Vidal Torreira Alvaro 
Published: March 2021

AbstractThe use of machine learning (ML)-based surrogate models is a promising technique to significantly accelerate simulation-driven design optimization of internal combustion (IC) engines, due to the high computational cost of running computational fluid dynamics (CFD) simulations. However, training the ML models requires hyperparameter selection, which is often done using trial-and-error and domain expertise. Another challenge is that the data required to train these models are often unknown a priori. In this work, we present an automated hyperparameter selection technique coupled with an active learning approach to address these challenges. The technique presented in this study involves the use of a Bayesian approach to optimize the hyperparameters of the base learners that make up a super learner model. In addition to performing hyperparameter optimization (HPO), an active learning approach is employed, where the process of data generation using simulations, ML training, and surrogate optimization is performed repeatedly to refine the solution in the vicinity of the predicted optimum. The proposed approach is applied to the optimization of a compression ignition engine with control parameters relating to fuel injection, in-cylinder flow, and thermodynamic conditions. It is demonstrated that by automatically selecting the best values of the hyperparameters, a 1.6% improvement in merit value is obtained, compared to an improvement of 1.0% with default hyperparameters. Overall, the framework introduced in this study reduces the need for technical expertise in training ML models for optimization while also reducing the number of simulations needed for performing surrogate-based design optimization.
One-Step Synthesis of O-Self-Doped Honeycomb-Like Hierarchically Porous Carbons for Supercapacitors
Authors: Lin Shiying , Mo Lanlan , Wang Feijun 
Published: March 2021

Abstract
A facile and environmentally friendly approach to produce self-doped hierarchically porous carbon as electrode material for high-performance supercapacitor was demonstrated. Three-dimensional honeycomb-like hierarchically porous carbon was successfully obtained by one-step carbonization and activation of sodium carboxymethyl cellulose (CMC) via K2CO3. With the optimized temperature of carbonization and activation, the porous carbon material achieved well-shaped hierarchically pores (micro-, meso-, and macropores) like a honeycomb, ultrahigh specific surface area (1666 m2 g−1), as well as highly O-self-doping (3.6 at%), endowing an excellent electrochemical properties for the electrode in a three-electrode system. The porous carbon electrode material delivered a high specific capacitance of 300.8 F g−1 at 1 A g−1, an eminent rate capability of 228.4 F g−1 at the current density up to 20 A g−1 and outstanding cycle stability of 94.3% retention after 10,000 cycles. Therefore, the CMC-derived hierarchical porous carbon activated by K2CO3 would have promising foreground in the application of supercapacitors.
Ultrasonic Structural Health Monitoring Approach to Predict Delamination in a Laminated Beam Using d15 Piezoelectric Sensors
Authors: Altammar Hussain , Salowitz Nathan 
Published: March 2021

Abstract
Ultrasonic structural health monitoring (SHM), employing embedded piezoelectric elements to actuate and sense ultrasonic waves, has greatly advanced in recent years. This paper presents a novel approach to address the prevailing challenges in the inspection of laminated structures for delamination using shear-mode (d15) piezoelectric transducers, composed of lead zirconate titanate (PZT). To experimentally evaluate the effectiveness of the proposed approach, a beam-like laminated specimen consisting of internally embedded d15 square PZTs was fabricated with simulated delamination at the interface of an adhesive joint. The evaluation of the results showed that the location of shear-mode actuators is a critical factor to detect delamination and to predict the propagation path of delamination. Delamination initiated close to actuators is more likely to be detected owing to their remarkable sensitivity of structural stiffness surrounding their region. The antisymmetric A0 wave mode generated by these actuators exhibits high interaction with damage, suggesting internally embedded d15 PZTs are a viable approach that can potentially advance the inspection tools of ultrasonic SHM.
Domain-Oriented Semantics for Feature Modeling Based on TAE Structures Using Conditional Attributed Rewriting Systems
Authors: Otto Harald E. , Kimura Fumihiko , Mandorli Ferruccio , Cugini Umberto 
Published: March 2021

Abstract
Requirements of intelligent CAD systems are aimed to enable them to support the designer throughout his/her entire activity, starting from conceptual design and ending with, according to given specifications, an almost complete design object description.
Current approaches featuring geometrical constraint-based systems with parametric or variational models, allow the designer to consider the realized design object description as an archetype of a family, based on a unique morphological model with unambiguous sets of parameterized rules. However, functionality for both design and reasoning, are limited to the low geometric level, leaving most of related information from the design intend and related technology unconsidered.
Our objective of given study is, to extend the present functionality of existing approaches by integrating different types of knowledge and incorporate dedicated semantics in form features and feature-based methodologies. As a basic representation, typed attributed entity structures (TAE) are used. Computation is performed over domain structured alphabets of attributed symbols using a conditional attributed rewriting system.
An application example in form of a wing rib, taken from aerospace engineering, is used, to verify and demonstrate the modeling and consistent handling of knowledge formations within our developed framework. Current limits of our new approach are discussed and a comparison related to the functionality of existing systems is undertaken, to direct the focus on further enhancements and extensions of our approach.
Feature-Based Modeling of Product Families
Authors: Laakko Timo , Mäntylä Martti 
Published: March 2021

Abstract
A feature-based product modeling system is introduced where the user can incrementally create and modify product families. Product family and feature descriptions are coded in a special definition language and can be easily added and modified by the user. The descriptions include dynamically maintained constraints. The definition language description of a new family can be automatically created on the basis of a recognized prototypical instance. A stored design history can be used for generating the geometry definition of the family.
Recognize Features From Freehand Sketches
Authors: Hwang Teng-Shang , Ullman David G. 
Published: March 2021

Abstract
A feature recognition system which allows the computer to capture sketches made by a mechanical designer is described. The system takes the user’s input sketching actions and interprets the collection of 2D geometric elements to extract 3D information from them in terms of mechanical features. A application domain, knowledge representation, the derivation of feature recognition rules, inference mechanism, and conclusions are presented in this article.
Handling Blending Features in Form Feature Recognition Using Convex Decomposition
Authors: Menon Sreekumar , Kim Yong Se 
Published: March 2021

Abstract
Form features intrinsic to the product shape can be recognized using a convex decomposition called Alternating Sum of Volumes with Partitioning (ASVP). However, the domain of geometric objects to which ASVP decomposition can be applied had been limited to polyhedral solids due to the difficulty of convex hull construction for solids with curved boundary faces. We develop an approach to extend the geometric domain to solids having cylindrical and blending features. Blending surfaces are identified and removed from the boundary representation of the solid, and a polyhedral model of the unblended solid is generated while storing the cylindrical geometric information. From the ASVP decomposition of the polyhedral model, polyhedral form features are recognized. Form feature decomposition of the original solid is then obtained by reattaching the stored blending and cylindrical information to the form feature components of its polyhedral model. In this way, a larger domain of solids can be covered by the feature recognition method using ASVP decomposition. In this paper, handling of blending features in this approach is described.
Design for Injection Molding: Using Process Simulation to Assess Tolerance Feasibility
Authors: Busick David R. , Beiter Kurt A. , Ishii Kos 
Published: March 2021

Abstract
This paper proposes an effective use of process simulation in the dimensional tolerancing of injection molded thermoplastic components. The complexities of the injection molding process make it difficult for designers to assign dimensional tolerances. No standard method exists for predicting the feasibility of a design tolerance. Advances in injection molding simulation software offer information that could aid in tolerancing. However, engineers have not effectively used these programs for tolerancing. This paper proposes a methodology for using process simulation in evaluating the feasibility of a tolerance scheme. The methodology entails using simulation to quantify the dimensional errors due to process variations and estimate sensitivities. Comparison of simulation results with tolerances specified by designers helps them evaluate whether the desired tolerances are feasible. The paper describes the steps required for estimating the dimensional errors and defines criticality as a measure of tolerance feasibility. A plastic housing for an electrical switch serves as an illustrative example.
An Expert Consultation Environment for Creating Customized Knowledge-Based Systems for CAD
Authors: Narayanan Parasuram , Jayaram Sankar 
Published: March 2021

Abstract
Although the field of CAD has come a long way in recent years, the integration of CAD with engineering/mechanical design, especially the integration of CAD with conceptual design, has not been given enough importance. Tools which facilitate the custom development of conceptual CAD software are still not available. This is especially true in the case of intelligent CAD systems. This paper describes the philosophy and design of a framework which will facilitate the creation of knowledge-based expert systems to support conceptual design.
The design of an object-oriented framework which will assist in the creation of customized expert systems for CAD applications is presented. This framework, known as the Expert Consultation Environment, provides the CAD programmer with tools to create the expert system. This framework consists of various object-oriented classes which the programmer would use during the creation of the knowledge-based expert system. A prototype of a portion of the framework was implemented. The use of this prototype framework in the creation of an expert system for a multi-disciplinary design application is discussed. The framework described in this paper would assist the programmers of CAD systems in building expert systems that are tailor-made for conceptual design. Any expert system created using an implementation of this framework will be very flexible, adaptable, and extendible.
A Semantic Framework for Flexible Feature Validity Specification and Assessment
Authors: Bidarra Rafael E. , Teixeira José C. 
Published: March 2021

Abstract
Feature-based modeling is being given an increasing significance in the development of computer-aided design environments, due to its expressive power in capturing various aspects of designer intent. Integrity problems arise, however, when the specification of complex shapes requires several features to overlap or interact. In this paper we address the problem of form feature behavior representation for such situations, developing a semantic model that captures the actual contribution of each feature in the overall model shape. Within this semantic framework it becomes possible to establish naturally and flexibly the desired validity conditions for each feature class, enhancing a modeling system with the ability for permanently monitoring each feature’s conformity with that original specification.
Towards Automated Construction of Molds and Dies
Authors: Rosen David W. 
Published: March 2021

Abstract
Starting with the motivation to provide manufacturing feedback to designers and to reduce bottlenecks in the design-manufacturing transition, algorithms for constructing molds and dies are presented. The concept of “virtual manufacturing” serves as the umbrella for this work. Computational prototypes, rather than hardware prototypes, can greatly speed product development, process design, and process tooling development. The work presented here contributes directly to all three areas, since automated tool construction enables accurate, detailed Design-for-Manufacturing feedback to aid product development, enables process design through simulation, and provides an initial tool design that can be enhanced by a tool fabricator.
A series of algorithms are presented for the automated construction of tools from a purely geometric reasoning viewpoint. Starting with a solid model of a component, undercuts are found and classified, then moving tool sections are constructed. For external undercuts, accessibility directions are found and are used to construct tooling side actions. Automated undercut accessibility determination has not been previously previously reported in the literature. For internal undercuts, form pins are constructed that access the undercut through the core of the tool. Undercut classification is important since their cost implications can be reported back to the component designer during design. Two examples illustrate the application of the algorithms.
Concurrent Engineering for Composites: Requirement Analysis About the Environment
Authors: Zhang Jian , Hahn H. Thomas 
Published: March 2021

Abstract
This paper has first examined the manufacturing process of composites and the feasibility to apply concurrent engineering idea to improve its productivity. Then the key components including their roles played in the manufacturing process of composites and the requirements to the CE system for composites have been properly identified and analysed. Based on these requirements, an infrastructure based system architecture for the CE system was designed. Finally, the scheme to implement a CE system for composites was presented.