CAD Environment Research Articles

SOLID-BODY SIMULATION OF SHOE LAST ELEMENTS FOR MANUFACTURE OF SHOES OF HIGH COMFORT

Purpose. Investigate the process of adjusting the shape of the shoe last by modeling solid elements (individual overlays) made by 3D printing. Methodology. We used a three-dimensional graphic environment Delcam Crispin with the use of modules ShoeMaker, LastMaker, PowerShape, which provide a full cycle of design processes of shoe production from processing scans of the feet, modeling the top design to the design of the last; Ultimaker Cura slicer to customize the printing of prototypes, made of different polymeric materials. The FDM method for 3D printing was used to study the adjustment of a shoe last with a printed cover. Results. The proposed sequence of adjusting the shape of the lasts using solid modeling in CAD environments Delcam Crispin LastMaker and PowerShape allows for design and technological preparation for the manufacture of corrective lasts by 3D printing. The end result of the last adjustment process is a digital copy of the prototype last, which can be used to model shoes in the 3D space of modern CAD. To achieve improved performance in the use of lasts made by 3D printing, the physical and mechanical properties of polymeric materials were determined, experimental tensile studies of samples obtained by 3D printing on an upgraded bursting machine 2167 P-50. Elastan D70 was chosen from the researched materials, which satisfies the physical and mechanical characteristics for the production of the last cover and subsequent operation of the product. Scientific novelty. Adjustment of the form and the sizes of a block is carried out at the expense of use of overlays made by a method of 3D printing which considers deviations of the sizes and the form of a block and foot of the individual customer. Practical value. The paper proposes an improved method of adjusting existing lasts with the help of printed overlays in anthropometric areas, which require completeness adjustment for individual consumers. It is the adjustment of the last with the help of printed lasts made of polymeric materials that will significantly reduce the production time, reduce the cost and commissioning of shoe lasts to individual order.

3D Interpreted Model: A Novel Product Definition Model by Integrating and Fusing a 3D Annotated Model and Design Knowledge

Model based definition (MBD) is the core of product digital research and development. The extension of the scope and content of the product model is an important way to improve the application ability of MBD methodology. In view of the demand of the development of the product definition method and the lack of systematic theoretical methods to support the further improvement of product model quality and ability, this paper proposes the concept of a 3D interpreted model as a new product definition model by integrating and fusing design knowledge on the basis of the MBD model. Firstly, the concept, characteristics and representation method of the 3D interpreted model are elaborated. Then, the construction method of the 3D interpreted model is proposed, which includes two steps. The first step is design knowledge annotation, which is used to integrate design knowledge with the MBD model and form the 3D interpreted model in a CAD environment. The second step is information extraction and knowledge fusion, which is used to construct a 3D interpreted model network by processing the product information and design knowledge stored in a STEP file and knowledge index file, respectively. Finally, a prototype system is developed, and the construction process of a 3D interpreted model is demonstrated and verified through an example. The results show that as a new product definition model, a 3D interpreted model realizes the comprehensive integration of a MBD model and design knowledge, so as to realize the inheritance and development of the product definition method, and supports business activities and saves more social resources.

Design of an innovative new extrusion system for a printing machine for ceramics

The introduction of ceramic materials in the medical field is becoming a vital necessity because of its stable physicochemical characteristics, high biocompatibility, and good osteoconductivity. On the contrary, machining ceramic components is difficult, owing to their extreme hardness and brittleness. Additive manufacturing (AM) technologies are an appropriate alternative to obtain the complex shapes of implants, which can have porous structures. Thus, since the development of 3D printing, direct ink writing (DIW) is one of the most promising and inexpensive techniques for shaping free-form ceramic medical components such as prostheses or dental implants from liquids or pastes. However, the assurance of performance criteria of the extrusion system for simultaneous usage becomes the major challenge for most direct ink writing (DIW) platforms, for instance for printing large parts, for multi-material printing, to decrease printing time, and to increase efficiency in terms of motor usage and weight of the extruders. To address the current deficiencies, a new extrusion system is designed for a 3D printing machine for ceramics that is compatible with different low-cost, open-source 3D printers. The proposed extrusion model enables printing with a loader with different syringes simultaneously, without stopping the operational process while switching the syringe. It adopts three subsystems. The automatic syringe loading system, which is operational to manually receive several syringes of the same or different volumes, allows the syringe feeding system to be loaded and unloaded once the syringe is empty. The syringes are automatically transferred to the holding system using an arm. The holding system allows the fixing of the syringe in order to perform printing with ceramic material. Pugh concept analysis was used to select the optimum design shape. After that, the 3D CAD environment was used to combine the strength of Pugh’s method and the design space. This brings a new concept into the mechanical design field for 3D printers, which is in line with the technological trends prevalent in the industry.

DESIGN AND DEVELOPMENT OF A NOVEL TESTING RIG FOR THE EXAMINATION OF ADDITIVELY MANUFACTURED AUXETIC COMPONENTS

AbstractThis paper reports upon the design and development of a novel testing rig for the examination of additively manufactured auxetic componentry. By firstly reviewing the key challenges for practical researchers and exploring the range of approaches used to examine auxetic structures, we subsequently introduce a new testing configuration seeking to enhance the existing methods found within the literature. The developed testing configuration includes a novel mechanical design with a new method for component mounting offering advanced control of the boundary condition and a fully developed control interface which facilitates real-time analytics, a range of data acquisitions and integration with a CAD environment. This paper describes both the development of the mechanical design and the development of the control interface by exploring the key design features and documentation of the manufacturing and assembly process. Finally, we discuss how the presented testing configuration offers a new and flexible way of testing auxetic componentry with additional insights offered for future researchers who wish to recreate or adapt the testing setup for their own examinations of additively manufactured componentry.

Hospital layout design renovation as a Quadratic Assignment Problem with geodesic distances

Hospital facilities are known as functionally complex buildings. There are usually configurational problems that lead to inefficient transportation processes for patients, medical staff, and/or logistics of materials. The Quadratic Assignment Problem (QAP) is a well-known problem in the field of Operations Research from the category of the facility's location/allocation problems. However, it has rarely been utilized in architectural design practice. This paper presents a formulation of such logistics issues as a QAP for space planning processes aimed at renovation of existing hospitals, a heuristic QAP solver developed in a CAD environment, and its implementation as a computational design tool designed to be used by architects. The tool is implemented in C# for Grasshopper (GH), a plugin of Rhinoceros CAD software. This tool minimizes the internal transportation processes between interrelated facilities where each facility is assigned to a location in an existing building. In our model, the problem of assignment is relaxed in that a single facility may be allowed to be allocated within multiple voxel locations, thus alleviating the complexity of the unequal area assignment problem. The QAP formulation takes into account both the flows between facilities and distances between locations. The distance matrix is obtained from the spatial network of the building by using graph traversal techniques. The developed tool also calculates spatial geodesic distances (walkable, easiest, and/or shortest paths for pedestrians) inside the building. The QAP is solved by a heuristic optimization algorithm, called Iterated Local Search. Using one exemplary real test case, we demonstrate the potential of this method in the context of hospital layout design/re-design tasks in 3D. Finally, we discuss the results and possible further developments concerning a generic computational space planning framework.

Simplifying Computer Aided Ergonomics: A User-Product Interaction-Modeling Framework in CAD Based on a Taxonomy of Elementary Affordances

OCCUPATIONAL APPLICATIONS This contribution provides a framework for modeling user-product interactions (in CAD) for in-depth ergonomic analysis of product design, using digital human models. The framework aims to be applicable to a wide range of different products while being suitable for designers – especially those who do not have specialized ergonomic expertise or training in human behavior – by providing an intuitive, standardized, and time-efficient modeling procedure. The framework contains 31 elementary affordances, which describe mechanical dependencies between product geometries and human end effectors. These elementary affordances serve as a tool for interaction modeling. Additionally, the paper provides a taxonomy of elementary affordances, which can be used to formalize / abstract the nature of user-product interactions and to describe them as elementary affordances. Furthermore, an implementation of the interaction-modeling framework is presented in a CAD environment and provides an example of how the framework could be used in terms of a computer aided ergonomics tool.

APPLICATION OF PARAMETRIZATION OF CHARACTERISTIC CROSS SECTIONS OF OBJECTS FOR INDIRECT PARAMETRIZATION OF THEIR 3D MODELS IN AUTOCAD CAD

The developed algorithm of indirect parametrization of 3d model of a typical part by means of parametrization of its longitudinal section is presented in the work. Controlling the shape of 3d objects by parameterizing their 2d cross-sections allows, using AutoCAD CAD, to create variants of electronic models of parts, the same type in geometry and different in size characteristics. This saves resources that are spent on design work. The proposed algorithm for creating parameterized 3d models in the CAD environment AutoCAD can be used in engineering practice. Currently, methodological developments have been introduced into the educational process at the Kyiv Polytechnic Institute named after Igor Sikorsky when teaching the course "Engineering and Computer Graphics".

A method to determine the topology of custom torsional elastic element for the lightweight rotary series elastic actuator

Compact and lightweight rotary series elastic actuator (SEA) is a new scheme to realize safe and friendly human-robot interaction of exoskeletons and other human-robot interaction applications. The custom monolithic torsional elastic element is a good choice for the compact design of rotary SEA, but there is a lack of guidance on selecting the topology of elastic elements in a lightweight SEA design. In this paper, with the help of the concept of specific energy, a method based on finite element simulation environment and parametric 3D CAD environment is proposed to determine the topology of the elastic element suitable for lightweight SEA by maximizing the specific energy. By adopting this method, we come to this conclusion: The topology, Archimedes-spiral-based double spiral structure without the outer ring, can be determined as a suitable topology of elastic element for a lightweight rotary SEA.

Construction project of a long reach compact excavator

The purpose of thesis was to comprehensively develop the construction project of a long reach compact excavator. Optimal solution was selected and its frames were determined by carrying out classic structural calculations. Then, based on them, a preliminary three-dimensional model was designed in the CAD environment. The prototype was subjected to a series of verification calculations and simulation tests using the finite element method under typical, but also non-standard operating conditions. Then, the structure was optimized and then tested again. Next, technical documentation of the final version was created. In the final part of work, technical and operational parameters of designed compact excavator were summarized and the direction of further actions was determined. The thesis ended with a summary of the observations arose during its implementation.

Surfer: A fast simulation algorithm to predict surface temperatures and mean radiant temperatures in large urban models

Outdoor thermal comfort simulation simulations rely on the mean radiant temperature (MRT) seen by pedestrians as an important input that remains difficult to compute. Especially for large urban models, computing relevant surface temperatures and radiation fluxes that make up the MRT is a daunting task in terms of simulation setup and the computational overhead. We propose a new algorithm to estimate exterior surface temperatures of building facades, roofs, and ground surfaces in an arbitrary urban 3D model. The algorithm discretizes all model surfaces and clusters them by material properties and sky and sun exposure to reduce computational complexity. The model setup is fully automated, and the algorithm is implemented in the popular Rhino3d CAD environment. We demonstrate the accuracy of the algorithm by comparing both the resulting external surface temperatures against a high-fidelity simulation and the final MRT against real-world measurements. We report an RMSE of 1.8 °C and 2.0 °C, respectively, while reducing simulation times by a factor of ~80. Envisioned applications of the algorithm range from rapid microclimate simulations in fast-paced urban design processes to large scale urban comfort evaluation of existing cities.

Analytical Surface Potential-Based Compact Model for Independent Dual Gate a-IGZO TFT

A surface potential-based compact model for independent dual gate (IDG) amorphous In-Ga-Zn-O thin-film transistors (IDG a-IGZO TFTs) is proposed here. The transport theories of percolation conduction, trap-limited conduction (TLC), and variable range hopping (VRH) in extended and localized states are first considered simultaneously via Schroder method, obtaining a physical description of the transport mechanism under different conditions of temperature and gate voltage. Moreover, a single formulation of front and back surface potentials which is valid and extremely accurate in all operation regimes is developed. Based on the transport theories and surface potentials, the complete compact model is developed and verified using both numerical simulation and experiment with an excellent agreement, and the threshold compensation effect is also included. Finally, the compact model is coded in Verilog-A, and implemented in a vendor CAD environment, which suggested that the proposed model can be successfully applied to circuit design.

Automatic Generation of Water Distribution Networks from Streets Layout

This article focuses on creating a model for the automatic generation of the EPANET input file from the layout of the arrangement of the streets designed in a CAD environment. From this layout a binary image is built, in which each pixel will be black if is inside the street and, otherwise, white. In order to determine the location of the pipes and nodes that are in the middle of the streets, the Zhang and Suen method of thinning binary images was used. After the image was thinned, the main challenge was to identify the pixels that will be considered as nodes of the network due to the irregular geometry of the streets. To solve this problem, a set of algorithms was developed on the theme of binary image processing. Two street layouts were used, one hypothetical and the other real. For both layouts, the model proved to be efficient, automatically generating the EPANET input format file with the pipes located within the streets.

Evaluation of the Additive Manufacturability of CAD-Parts for initial Data Labelling in AI-based Part Identification

The objective of this study is to develop and implement an analysis tool that identifies CAD geometries which impair Additive Manufacturing. A key performance indicator is generated to be used as data label representing the manufacturability for a future application of AI. Relevant geometric features are identified and algorithms to evaluate critical features are developed. The analyses include part orientation, build volume, wall thicknesses, gap widths, bore and cylinder diameters as well as the process-specific factors powder removal and need for support structures. The manufacturability of a part is calculated as Additive Manufacturing Feasibility Indicator (AMFI), depending on the identified critical features and a user-specific weighting. The AMFI successfully serves as data label which is suitable for application in AI methods. The developed GUI supports designers by highlighting critical features directly in the CAD environment and allowing the user in a purposeful part optimization for AM.

Modelling of machining center vibration stability by the D-partitions method

The stability of operation, vibration-free processing of products various types at high-speed machining centers suggests the improvement of research in the field of the dynamics of machine tools and their main forming units. The three-dimensional models of the forming spindle node and the corner table of the machining center for the drilling-milling-boring type in the CAD environment KOMPAS-3D have been developed. An algorithm for analyzing the dynamic quality of the machine elastic parts based on the constructed static and frequency formular in the mathematical environment MAPLE is proposed. Programs have been developed and graphs of the main frequency characteristics and the hodograph of the transfer function for the spindle node in the specialized Signal Processing module have been obtained. The method of D-partitions using to estimate the vibration stability of the forming units on an example of 4 coordinate milling machining centers is introduced. Experiments on two variants of technological adjustments with different dimensions of the tool block (the cantilever part of the spindle assembly) were carried out. The analysis of stability in the plane of the cutting process optimized parameter (specific cutting force) was carried out. The region and the boundary of the stable functioning of the machine and, on this basis, the optimum modes of machining by the criterion of vibration stability are revealed.

Повышение быстродействия многоразрядного арифметико-логического устройства

In modern microprocessors to reduce the time resources the arithmetic-logic units (ALU) with an increased organization of arithmetic carry, characterized by high speed, compared to ALU with sequential organization of the arithmetic carry, are commonly used. However, while increasing the bit number of the input operands, the operating time of ALU of ALU with the accelerated arithmetic carry increases linearly depending on the number of bits. Therefore, the development of ALU, providing higher performance than the existing known solutions, is an actual task. In this work the analysis of ALU with sequential and accelerated organization of the arithmetic carry has been performed. To increase the speed of the operation, a multi-bit ALU has been developed. The simulation of ALU circuits has been executed in Altera Quartus –II CAD environment. The comparison has been performed by the number of logical elements and the maximum delay as a result of modeling the ALU circuits for 4, 8, 16, 32, and 64 bits. A scheme for checking the results has been implemented to confirm the reliability of developed ALU. As a result, it has been found that when performing operations with the 64-bit operands, the developed ALU reduces the maximum delay by 53 % compared to ALU with sequential arithmetic carry and by 35.5 % compared to ALU with the accelerated arithmetic carry, respectively.

Sensitivity Enhancement of Methane Detection Based On Hollow Core Photonic Crystal Fiber

Monitoring methane (CH4) concentration is essential in many industrial and environmental applications. Emission of such gases is indeed important to detect for health, safety and environmental reasons. The major risk in all these areas is an explosion hazard, which may occur if methane reaches its Lower Explosive Limit (LEL) of5% concentration in air. For that reason, it is necessary to develop gas sensors to monitor that methane levels below this value. Due to a weak absorption of methane, this gas is difficult to detect using conventional methods.Hollow core photonic crystal fibers (HC-PBF) have emerged as a promising technology in the field of gas sensing. The strong interaction achievable with these fibers are especially advantageous for the detection of weakly absorbing regions of methane. In this paper, we investigated, by full vectorial finite element method (FV-FEM) in Rsoft CAD environment, the dependency of relative sensitivity on the fiber parameters and wavelength. Consequently, we introduced the optimal structureof an index guiding hollow core photonic crystal fiber capable of measuring methane concentrations down to 0.1%in air. The simulations showed that the sensing sensitivity increased with an increase in the core diameter and a decrease in the distance between centers of two adjacent holes.

Self-trained CAD assistance for constraining assemblies based on decision trees and support vector classification

In this publication a concept for a self-trained assistance is presented, which places a part, selected by the designer, into an assembly and fixates it with constrains. Therefor all selectable parts are classified by the assistance beforehand. In the process of developing the classification several algorithm were tested and compared regarding speed and precision. To place and constrain the parts, decision trees for supervised learning were arranged in a multi-step structure. Furthermore, the implementation in the CAD environment Fusion 360 as well as the limitations and potentials of the concept are discussed.

Analysis of Selected IT Tools Supporting Eco-Design in the 3D CAD Environment

The concept of eco-design is an area of interest of many manufacturers. Its implementation provides a framework that allows companies to adapt to the requirements of sustainable development related to the design and manufacturing of environmentally-friendly products. Implementation of eco-design in the industry requires dedicated information technologies. Many types of software tools are offered which support eco-design, and the choice of the one which suits the user best is not easy. The paper describes an analysis of three selected IT tools dedicated to the environmental assessment of products, integrated with the 3D CAD environment. The analysis has been carried out on the basis of specially developed reference models of sets (assemblies) imitating small household appliances. The models have been designed to support the creation of various configurations of connections between elements (parts of the assembly). The study experiments consist in changing the configurations and observing how the changes affect the environmental parameters of the modelled structure. The results have been used to describe the scope of support offered by each of the tools under analysis and their suitability for the environmental assessment of products.

Topology optimization with precise evolving boundaries based on IGA and untrimming techniques

We present a new computational approach to topology optimization that includes precise representation of the boundaries as they evolve during optimization. The topology is defined following level set methods where a B-spline surface is used to parameterize the level set function. In each optimization cycle, the level set based topology is mapped into a spline-based representation that is constructed on an unstructured mesh. The mapping procedure is performed following untrimming techniques which lead to geometrical models whose boundaries are explicitly defined as cubic B-spline curves. The geometrical model is replicated precisely by mesh refinement to obtain a suitable model for subsequent Iso Geometric Analysis (IGA). It is shown that accurate stress evaluations are obtained on the untrimmed boundaries. Consistent sensitivity analysis is formulated to account for all mappings and refinements from the underlying level set function to the IGA-based solution of the mechanical response. Implementation of the proposed approach is demonstrated on compliance and maximum stress minimization problems. Several design aspects are examined, namely integrating a topological derivative technique for hole insertion; a control points mapping procedure; and imposing predefined fixed void regions. The results expose the capability of the proposed approach to generate optimized layouts while accurately modeling the boundaries throughout the optimization process. Furthermore, the outcomes are spline-based optimized topologies that are directly compatible with CAD environments.

Novel method for determining bone dimensions relevant for longitudinal and transverse distraction osteogenesis and application in the human tibia and fibula

BackgroundIn distraction osteogenesis (DO) of long bones, new bone tissue is formed and distracted to lengthen limbs or reconstruct bone defects. However, certain anthropometric quantities relevant for biomechanical modelling of DO are unknown, such as areas where new bone tissue is formed. We developed a novel method to facilitate the determination of these distraction areas (DA), which we applied in the tibia and fibula of adults for longitudinal and transverse DO to advance knowledge of anatomical boundary conditions. MethodsCT data sets of 21 adult human tibiae and 24 fibulae were selected for investigation. Volumetric models were created utilizing image segmentation. The DA for longitudinal DO was determined in a CAD environment using the total bone cross section in the proximal, central and distal diaphysis of the tibia and fibula. Additionally, the medullary canal area was determined in the fibula. Furthermore, we measured the total DA and medullary canal DA for transverse distraction using a longitudinally split fibula with an osteotomy length of 8, 12, 16 and 20 cm. The osteotomy plane was oriented in medial and anteromedial direction. Finally, Spearman analyses were conducted to assess the correlation between bone length and DA. ResultsFor longitudinal DO, the mean total DAs were 878, 535 and 482 mm2 in the tibia and 132, 153, 124 mm2 in the fibula for the proximal, central and distal diaphysis, respectively. Regarding transverse distraction, the mean total DAs for a medial and anteromedial osteotomy plane orientation were 962, 1423, 1868 and 2306 mm2 as well as 925, 1387, 1844, 2279 mm2 for an osteotomy length of 8, 12, 16 and 20 cm, respectively. Weak, positive, and non-significant correlations were observed when correlating bone length and DA in the tibia and fibula. ConclusionsQuantification of DAs and hence distracted callus tissue in DO advances anatomical knowledge and improves biomechanical modelling by adding a parameter which cannot be approximated based on bone length.