Product Geometry Research Articles

Interpretation of the effect of transient process data on part quality of injection molding based on explainable artificial intelligence

This paper proposes an interpretation methodology for the effect of transient process data on quality of injection molded parts. The transient process data measured in the actual processing space have been regarded as the most relevant information to manufacturing processes and product quality. However, its interpretation to pinpoint which feature in the data would affect part quality has traditionally relied on knowledge and understanding of the manufacturing process. The main objective of this method is to reduce the dependency of the transient process data analysis on process knowledge and understanding by using explainable artificial intelligence (XAI). The contribution of the ‘section-wise' features in the transient process data to the quality prediction of machine learning (ML) models was investigated for the first time. The interpretation results of the effect of cavity pressure and mold surface temperature on four different quality factors represented reasonable explanations of the characteristics of the polymer materials, product geometry, and molding process. Due to the intermediate relationship of the transient process data with the user-specified process parameters and the resulting quality variables, the interpretation results can be further utilized to optimize the process and provide the optimal transient process data profile for best part quality.

Influence of shape distortion on the precision of holes in parts fabricated by metal binder jetting

Metal binder jetting (MBJ) is an additive manufacturing (AM) technology split into two process steps: printing and sintering. Firstly, product is built up layer-by-layer by the selective deposition of a binder agent on a powder bed. Secondly, a thermal treatment (sintering) consolidates the metal structure. MBJ is currently becoming more and more attractive on the reason of high potential scalability, cost-effective production and wide range of available material feedstocks. However, the transition towards industrial scale production is restrained by the critical control of dimensional and geometrical precision of parts after sintering operation. In fact, product geometry is affected by anisotropic dimensional change or even shape distortion. This study aims at investigating the dimensional and geometrical precision of through holes. Three sample geometries were designed, having a through hole with axis perpendicular to the building direction and located at different levels along sample height. Samples were measured by a coordinate measuring machine before and after sintering, in order to assess the shrinkage and any shape change. Results highlight the inhomogeneous volumetric and linear shrinkage of the three geometries, which is influenced by the printing position in the building plane. A macroscopic deformation of parallelepiped geometry was also evidenced, caused by the superposition of layer shifting originated on printing, and by the frictional forces between sample surface and alumina support during sintering. Such distortion significantly affects the shrinkage and form error of holes.

Engineering eco-design of heat exchangers in domestic heating systems using life cycle assessment methodology

According to the European energy consumption reports, the highest energy/fuel consumption in the residential sector is due to space heating, followed by water heating. Generally, the product used to warm water in residential buildings is a boiler system where a heat exchanger is the core of the system. The paper provides a Life Cycle Assessment analysis of a traditional heat exchanger used in domestic boilers with the aim to identify critical aspects and environmental hotspots for the development of a novel concept of the heat exchanger. The methodology used to collect eco-design guidelines from the Life Cycle Assessment analysis is proposed within the paper. Several eco-design actions were put into practice to reduce the environmental issues in each phase of the life cycle from the materials used, the manufacturing processes as well as the product geometry to increase energy efficiency during the use. Concerning the materials and manufacturing phase, a novel design based on a different material (e.g., stainless steel) was developed to replace a mix of materials (i.e., copper and aluminum alloy). Concerning the use phase, the overall product efficiency was increased allowing important savings in terms of gas/energy consumption, by the adoption of a novel design (e.g., spiral pipe). The new heat exchanger design shows better environmental performance in each Life Cycle Assessment indicator, saving more than 40% in CO2 emissions (Global Warming Potential) in the whole product life cycle.

Entanglement entropy in internal spaces and Ryu-Takayanagi surfaces

We study minimum area surfaces associated with a region, R, of an internal space. For example, for a warped product involving an asymptotically AdS space and an internal space K, the region R lies in K and the surface ends on ∂R. We find that the result of Graham and Karch can be avoided in the presence of warping, and such surfaces can sometimes exist for a general region R. When such a warped product geometry arises in the IR from a higher dimensional asymptotic AdS, we argue that the area of the surface can be related to the entropy arising from entanglement of internal degrees of freedom of the boundary theory. We study several examples, including warped or direct products involving AdS2, or higher dimensional AdS spaces, with the internal space, K = Rm, Sm; Dp brane geometries and their near horizon limits; and several geometries with a UV cut-off. We find that such RT surfaces often exist and can be useful probes of the system, revealing information about finite length correlations, thermodynamics and entanglement. We also make some preliminary observations about the role such surfaces can play in bulk reconstruction, and their relation to subalgebras of observables in the boundary theory.

Cure cycle optimization of infrared cured composites using Taguchi method

AbstractKnowing that cure cycle has a significant effect on the mechanical properties of the composite materials, determining the effects of cure cycle parameters – such as heating rate, maximum temperature, and dwell time, has gain importance. This study addresses the optimum cure cycle of an infrared cured carbon fiber pre‐preg material. An infrared oven equipped with 1 kW halogen infrared heating unit and vacuum system was used. Different cure cycles determined by means of Taguchi experiment design approach and a cure cycle was found maximizing the tensile strength of the material. Results showed that infrared curing is a strong alternative to the autoclave despite its shortcomings regarding the product geometry. The optimized cure cycle showed 23% increase in the tensile strength comparing the tested cure cycle which is resulted with the minimum tensile strength. Besides, comparing the specimens cured with the optimum cure cycle, the infrared cured specimens showed slightly higher tensile strength than the autoclave cured counterparts. According to Taguchi optimization, optimum values for maximum tensile strength were found as 10°C/min, 130°C for heating rate and 60 min for plateau time. According to the analysis of variance, the most effective parameter affecting the tensile strength was the heating rate.

Potential energy curve for singlet-oxygen quenching reaction by vitamin E

The singlet-oxygen (1O2) quenching-reaction by vitamin E (α-tocopherol) was studied by using density functional theory, and the potential energy curve was calculated. On the basis of the computational results, the following mechanism was suggested for the quenching reaction. In the initial stage of the quenching reaction, 1O2 and α-tocopherol approach each other, a partial electron transfer takes place from α-tocopherol to 1O2, and an exciplex between the two molecules is formed. Further approach raises the potential energy of the exciplex and leads to a crossing point between the potential energy curves of the lowest singlet and triplet states. Then, physical quenching from 1O2 to 3O2 is caused by α-tocopherol. Even more approach of 1O2 and α-tocopherol yields a pseudo-stable 6,8a-endoperoxide of α-tocopherol after passing through a transition state. The 6,8a-endoperoxide could be transformed to the primary product (8a-hydroxyperoxy-α-tocopherone) of a chemical reaction between 1O2 and α-tocopherol. The geometries at the potential energy minima and the transition state in the lowest singlet state were optimized, and the geometry at the potential-energy curve crossing-point between the lowest singlet and triplet states was obtained besides stabilization and activation energies included in the potential energy curve. The geometry of the primary product of the chemical reaction was also optimized.

Design and Manufacturing of Spark Plug and Injector using Rapid Prototyping

Rapid prototyping is a technique generally used for manufacturing complex product geometries, which otherwise require to produce with multiple operations and processes using traditional manufacturing. This paper discusses about 3D modelling in CATIA, its features, benefits, and how it is used in the engineering design process. CATIA offers various features, including parametric modelling, assembly modelling, surface modelling, and drafting, which provide many benefits such as increased design accuracy, improved design communication, faster design iterations, and reduced manufacturing costs. 3D modelling is an essential part of the engineering design process and is used for conceptual design, detailed design, and manufacturing. The rapid prototyping process involves creating a digital model, slicing the model, preparing the printer, printing the model, and finishing the model. This paper describes real-time design and manufacturing of spark plug and injector using Rp machine.

Теория нагружения синтетических рыболовных материалов

An important task of mechanics of synthetic fishing twisted rope and string products and braided cords is to create a fundamental basis for describing their fracture processes during deformation in operation, i.e. to develop a framework for fracture mechanics (building models and algorithms for calculating structures and technological processes at large plastic deformations, taking into account fracture). There is considered the necessity of developing and introducing the simple and at the same time effective criteria of destruction, allowing to estimate reliably the conditions of safe operation of twisted rope and string products, threaded products and braided cords and especially the structures of industrial fishing gear. Determination of stress concentrations, is an obvious task in connection with the creation of new fishing trawls, purse seines and grips with complex shape-changing geometry. This problem is actual for many branches of industry, including transport and machine-building, where at the designing stage it is necessary to take into account possible emergency situations caused by intensive dynamic effects in twisted rope and string, threaded products and braided cords. Components and structures of twisted rope and string products, threaded products and braided cords should withstand the specified loads in a wide range of loading rates. In particular, the theory allows to solve nonlinear problems, taking into account changes in geometry of deformable twisted rope and string products, threaded products and braided cords, as well as to obtain analytical solutions of various problems.

Features of Crevice Corrosion of Different Grades of Duplex Stainless Steels

Duplex stainless steels (DSSs) are being increasingly employed in the oil and gas and chemical industries, which, despite their high alloying degree and high resistance to general corrosion, are subject to pitting and crevice corrosion. According to their resistance to pitting and crevice corrosion, steels are ranked according to the PREN. However, nowadays there are many grades of DSSs, in which the content of Cr, Mo and N varies in different quantities, therefore the selection of the grade must be carried out with great care, considering not only PREN, but also the production technology, operating conditions, and the geometry of products. The crevice corrosion behaviors of three grades of duplex stainless steels quenched from 1050, 1100 and 1200 °C were studied in FeCl3 solution at 50°C. It is shown that PREN allows to rank only different grades in terms of corrosion resistance. With a constant PREN value, but with different contents of ferrite and austenite in steel, completely different values of the corrosion rate can be obtained, therefore, PREN must be used with great care. It was found that in the studied steels, the optimal ferrite content, at which the lowest crevice corrosion rate is achieved, is at 65 vol.%.

Comprehensive exploration of graphically defined reaction spaces

Existing reaction transition state (TS) databases are comparatively small and lack chemical diversity. Here, this data gap has been addressed using the concept of a graphically-defined model reaction to comprehensively characterize a reaction space associated with C, H, O, and N containing molecules with up to 10 heavy (non-hydrogen) atoms. The resulting dataset is composed of 176,992 organic reactions possessing at least one validated TS, activation energy, heat of reaction, reactant and product geometries, frequencies, and atom-mapping. For 33,032 reactions, more than one TS was discovered by conformational sampling, allowing conformational errors in TS prediction to be assessed. Data is supplied at the GFN2-xTB and B3LYP-D3/TZVP levels of theory. A subset of reactions were recalculated at the CCSD(T)-F12/cc-pVDZ-F12 and ωB97X-D2/def2-TZVP levels to establish relative errors. The resulting collection of reactions and properties are called the Reaction Graph Depth 1 (RGD1) dataset. RGD1 represents the largest and most chemically diverse TS dataset published to date and should find immediate use in developing novel machine learning models for predicting reaction properties.

Multiphysics Simulation of the Shape Prediction and Material Removal Rate in Electrochemical Machining Process

ABSTRACT The electrochemical machining process involves electrical and chemical processes while removing materials from the workpiece. Electrochemical machining (ECM) lacks accurate models for predicting the shape and material removal rate during the ECM process. This limits the ability to optimise the process and predict the final product geometry, which is crucial for industrial applications. This research mainly focused on the modelling and simulation of material removal from the workpiece using COMSOL Multiphysics software. This research involves developing a mathematical model that describes ECM’s electrical, chemical, and mechanical interactions. The model is based on electrochemistry, fluid dynamics, and solid mechanics principles and will be solved using numerical simulation techniques. Various workpiece materials considered in this investigation include Aluminium, Nickel, Stainless Steel, and Tungsten, whereas copper is electrode material. The effects of the various parameters, such as workpiece materials, the voltage applied during machining, and electrolyte conductivity on the material removal rate are being investigated. In addition, the shape of the machined workpiece is also predicted. The results of this research provide a deeper understanding of the underlying physics of the ECM process and lead to the development of more accurate models for predicting the shape and material removal rate during ECM.

Mechanical properties of starch bio-composite and molded pulp samples manufactured using pine and eucalyptus fibers

In recent years, one of the main challenges is to improve the mechanical performance of bio-composites to be used as structural parts for the construction, automotive, and aviation sector. This paper may contribute to developing durable structural bio-composite parts with starch addition. The mechanical properties of bio-composites reinforced by eucalyptus or pine fibers (48 wt %) compound with Cationic Starch (48 wt %) and Carboxymethyl cellulose (CMC) (4 wt %) were determined. The production method was a combination of molded pulp, extrusion, and compression molding production techniques. To see the effect of adding starch to bio-composites and different production methods, the mechanical performance of these natural fibers produced by the conventional molded pulp production method (without any additives) was also found and compared with the composite samples. Composite samples indicate significantly better tensile, flexural, and compressive values, at least four times, compared with the molded pulp samples. On the other hand, the molded pulp samples had more than 2 times better impact characteristics against composites. Using molded pulp technic in composite production (investigated in the study) is a new idea and may give some opportunities with its serial production compatibility and geometry freeness, to the industry.

Effect of different roll-forming flower patterns on coiled tubing ovality and pressure performance

The pressure applied by the drilling fluid circulation pumps into Coiled Tubing (CT) compensates for the effects of fluid friction and force applied to the downhole motors. The higher the pressure, the greater the power of the well operation. The critical point of the cross-section of CT is on the earth's surface, where the highest internal and lowest external pressure are applied to it. In this paper, the compressive tolerance value of CT is investigated in relation to its ovality. This ovality can be inherent and created during the construction of the tube. 4 different flower patterns can be used for making CT. This paper aims to roll forming CT without a sizing step so that it preserves its mechanical performance against incoming forces. The geometry-based form definition method calculations have been used to determine the forming path of the strip, and this is the basis for the design of the forming rollers in each stage, finally, according to the similarities in the forming stages, 45 rollers have been designed for simulation. Therefore, assuming that the sizing step is not used in tube roll forming, the effect of roll forming flower patterns on the ovality of the final product of 1 ½ inch CT-70 and its effect on the internal and external pressure tolerance of the tube is investigated and Results of dimensional analysis, a tensile test of a new QT-70, 1 ½ inch tube as a sample and the geometry-based form definition method results are considered as input for the simulation of all four methods and the finite element method was used to simulate tube construction with different flower pattern methods, and its results were used in the geometry of the final product, in CT pressure tolerance analysis. The results show that the behavior of the tube made by the reverse bending flower pattern method shows better tolerance against internal and external pressure so this behavior is related to the ratio of internal to external pressure tolerance in the tube. With the flower pattern method, the reverse bending is approximately 1.08–1.85 times compared to the double-radii pattern and 1.13 to 2.27 times, and 1.18 to 3.21 times compared to the edge flower pattern and circular flower patterns, respectively.

Relations between entropy rate, entropy production and information geometry in linear stochastic systems

In this work, we investigate the relation between the concept of ‘information rate’, an information geometric method for measuring the speed of the time evolution of the statistical states of a stochastic process, and stochastic thermodynamics quantities like entropy rate and entropy production. Then, we propose the application of entropy rate and entropy production to different practical applications such as abrupt event detection, correlation analysis, and control engineering. Specifically, by utilising the Fokker–Planck equation of multi-variable linear stochastic processes described by Langevin equations, we calculate the exact value for information rate, entropy rate, and entropy production and derive various inequalities among them. Inspired by classical correlation coefficients and control techniques, we create entropic-informed correlation coefficients as abrupt event detection methods and information geometric cost functions as optimal thermodynamic control policies, respectively. The methods are analysed via the numerical simulations of common prototypical systems.

Proposing an integrated indicator to measure product repairability

Repairing is one of the most relevant strategies within the Circular Economy (CE) concept since it contributes to waste prevention and extends product and components' lifespan. Thus, reparability becomes an essential issue from the early product design phases, where materials, geometries, and joints are defined. Despite some repairability indicators that can be found in the literature and are applied worldwide, there is a lack of connection between repairability and the early decision-making process for improving it from the design of components of subsystems of a product. To contribute in that research direction, this article presents the Product Repairability Index (PRI), which considers the intrinsic repairability of the product components, their assembly/disassembly complexity, repairing instructions, availability of spare parts, and the self-diagnosis aids provided by the product. The PRI also considers components' relative functional importance to identify those with higher repairability requirements concerning their functional importance in the whole product assembly. The proposed indicator has been applied to a coffee machine as a case study, following a step-to-step methodology and calculation criteria to generate a quantitative value and detect the possible aspects to redesign to make a product more repairable.

Geometry of CR-slant Warped Products in Nearly Trans-Sasakian Manifolds

A CR-slant warped product is considered a generalization of a CR-warped product. It was firstly introduced and studied in the field of Kaehler geometry. In this paper, we study CR-slant warped products in nearly trans-Sasakian manifolds. We obtain a general inequality related to the second fundamental form and the warping function in such warped products. The equality case is discussed.

Determination of Undercutting Avoidance for Designing the Production Technology of Worm Gear Drives with a Curved Profile

One of the most difficult production geometry tasks arising in the machining process of the elements of a drive pair is to avoid undercuts. It is a serious technological challenge to determine the production of the elements of worm gear drives avoiding the phenomenon undercut, especially in the case of a pair consisting of a curved profile worm and its mating wheel. The technology of forming the tooth surface requires a separate examination in each case, running the simulation procedure of the tool geometry and the movement conditions when forming different teeth. This article proposes a new concept for determining and then avoiding the positions of undercutting by examining the patented worm with a circular arc profile in axial section, due to its extremely advantageous aspect in terms of production technology. The cutting edge of the hob, formed from the substitutional worm, moves on the tooth surface of the worm, and produces the tooth surface of the conjugate wheel. The gear tooth surface has been determined based on the main law of gearing with the lines consisting of the contact points of the conjugated surfaces. The conditions for the disappearance of the common normal or the relative velocity fitting to the common tangent plane of the contacting points are defined in this paper.

Machine learning for predicting dimensions of extrusion blow molded parts: A comparison of three algorithms

In the perspective of feed-forward control through a manufacturing process chain, production data can be used downstream to correct subsequent processes and improve product quality. In an extrusion blow-moulding (EBM) use case, supervised learning (SL) has been applied to predict geometrical dimensions based on process data, as a possible basis for feed-forward control. The labeled tabular dataset showed signifcant time dependency which complicates the learning task. In this paper we present a time-series regression approach and compare three common SL algorithms – Random Forest, Gradient Boosting and XGBoost. The results show that only part of the variations in product geometry could be learned from process data and that future work will be necessary in order to increase the models’ performance.

First principles reaction discovery: from the Schrodinger equation to experimental prediction for methane pyrolysis.

Our recent success in exploiting graphical processing units (GPUs) to accelerate quantum chemistry computations led to the development of the ab initio nanoreactor, a computational framework for automatic reaction discovery and kinetic model construction. In this work, we apply the ab initio nanoreactor to methane pyrolysis, from automatic reaction discovery to path refinement and kinetic modeling. Elementary reactions occurring during methane pyrolysis are revealed using GPU-accelerated ab initio molecular dynamics simulations. Subsequently, these reaction paths are refined at a higher level of theory with optimized reactant, product, and transition state geometries. Reaction rate coefficients are calculated by transition state theory based on the optimized reaction paths. The discovered reactions lead to a kinetic model with 53 species and 134 reactions, which is validated against experimental data and simulations using literature kinetic models. We highlight the advantage of leveraging local brute force and Monte Carlo sensitivity analysis approaches for efficient identification of important reactions. Both sensitivity approaches can further improve the accuracy of the methane pyrolysis kinetic model. The results in this work demonstrate the power of the ab initio nanoreactor framework for computationally affordable systematic reaction discovery and accurate kinetic modeling.

Use of product geometry specifications in the design of 3rd generation combined bearing hubs

This article is an excerpt from the development of the technological process and implementation into production of a third-generation automotive hub assembled with a tapered roller bearing. The article addresses the use of ISO GPS standards and their application in determining geometric tolerances of a bearing hub. Their role in ensuring that the functional requirements specified by the designer and expected by the user are met is indicated. Using selected specifications as an example, the application of ISO GPS standards and their interpretation is shown. The paper uses four ISO GPS standards to define the dimensional and geometric characteristics of a combined bearing hub. These specifications will then be verified when the hub is put into production. For this purpose, a trial batch of third-generation combined bearing hubs will be produced. The conclusions point to the need for a standard dedicated to combined bearing hubs. along the lines of or in addition to ISO 492, which relates to rolling bearings. This need arises from the increasing popularity of the use of combined bearing hubs in automotive vehicles. The complexity of hub designs and their impact on fuel consumption and, above all, safety, makes bearing hubs a highly responsible component. The lack of a standard dedicated to combined bearing hubs forces designers to have, know and apply up to a dozen standards when designing combined bearing hubs.