Computer-aided Engineering Tools Research Articles

Structural optimisation for medical implants through additive manufacturing

Advanced manufacturing techniques are being explored to fabricate degradable and non-degradable, porous or non-porous implants for medical applications. These implants have been designed using standard computer-aided design (CAD) and computer-aided engineering (CAE) tools and produced in a multitude of materials. The recent use of optimisation techniques, mainly topology optimisation, allows the development of additive manufactured medical devices with improved performance. This review discusses the combined use of optimisation techniques and additive manufacturing to produce biocompatible and biodegradable scaffolds for tissue engineering with improved mechanical and permeability properties; metallic lattice structures with reduced weight and minimal stress shielding effect; and lightweight personalised orthopaedic implants. Three optimisation routes are considered: topology optimisation; triply periodic minimal surfaces that can be manipulated by means of the equations parameters to optimise the overall performance; and the use of repetitive structures that are optimised as unit cells under certain conditions to compose a bulk object. Major limitations and research challenges are highlighted and discussed.

A digital tool for integrating renewable energy devices within landscape elements: Energy-scape online application

There is a major shift toward integrating renewable energy (RE) within the urban context to create zero energy buildings, passive buildings and smart cities. Landscape approximately occupies 65% of the urban area, which nominates landscape to play a major role in generating energy from renewable sources (e.g. solar, wind, etc). In order to achieve this objective, “Energy-scape” elements have been introduced to generate clean and efficient energy by integrating renewable energy (RE) devices with landscape elements. Previous research presented Energy-scape database to help landscape and urban designers to replace landscape with Energy-scape elements and to focus on integrating renewable energy (RE) within the urban environment. Several architects and landscape designers still lack the basic knowledge of RE, never to mention, the complexity of Energy-scape database that is continuously updated. Furthermore, the lack of computer-aided engineering (CAE) tools that can help architects, designers and decision-makers to swiftly integrate RE devices with the urban environment is another barrier to spread the implementation of similar projects. This research attempts to overcome this challenge by introducing a new web-based application to design landscape while integrating Energy-scape elements in urban environment. The algorithm of this web-based application analyzes existing landscape based on existing resources to select suitable Energy-scape elements, required area, and the best suitable locations of these elements within a specific project. The proposed algorithm enables the users to modify suggested locations and area of the Energy-scape elements to meet the project’s needs in term of the available budget, area or the required energy production. Further, the new algorithm calculates the impact of integrating Energy-scape elements within the project in term of cost (e.g. capital and running costs), lifetime, and total energy saving. Moreover, the current paper introduces a simplified user-friendly web-based tool of the proposed new algorithm that will help architects and landscape designers to use Energy-scape elements efficiently within their projects. The efficiency of the presented web-based application will be tested in a case study of Al-Azhar Park in Cairo, Egypt to validate the software capabilities in a real-case scenario. The research concludes that the proposed software application is an effective tool for landscape designers to use Energy-scape elements through identifying the optimum type and location of them within landscape design projects and calculating the impact of using them in terms of energy-savings and carbon emission (CO2) reduction.

Manual 2-dimensional Fabric Steering, for the Manufacture of Variable Stiffness Panels

In recent years, Automated Fibre Placement has been applied in manufacturing variable stiffness panels containing continuously changing fibre paths. The aim is to achieve superior mechanical properties, compared to straight-fibre laminates [1,2]. This paper proposes a novel low-cost manufacturing technique, referred to here as ‘manual 2D fabric steering’. The process is able to manufacture similar variable stiffness panels to those produced using Automated Fibre Placement. By manipulating biaxial fabrics, curvilinear fibre paths can be created. The technique involves very low equipment costs and can be used to steer multiple-layers of fabrics simultaneously (in contrast to the tow-by-tow and layer-by-layer fibre deposition method in Automated Fibre Placement), leading to faster production rates and lower costs, at least for smaller production runs. A computer aided engineering tool, SteerFab [3], is used to guide the design and manufacture process by predicting: (a) the optimum 2D fibre paths, (b) the subsequent mechanical behaviour of the resulting variable stiffness panel (including improvements in buckling resistance) and (c), the step-by-step instructions for the actual manufacturing process. In this paper, manual 2D fabric steering is described and the effect of the manipulation sequence on the final steered fabric preform is investigated. The repeatability of the process is also examined.

A Methodology for Product Development in Mobile Machinery: Case Example of an Excavator

Digital tools have become indispensable for the testing and modification of prototypes in mobile and industrial machine manufacturing. Data that are extracted from virtual experimentation and analysis are both affordable and valuable, due to their repeatability and because they are close to real-world observations. Expert knowledge is a prerequisite for full deployment of computer aided engineering tools in the design phase and concomitant stages of product development. Currently, such knowledge, for the most part, is provided by the product development team and the manufacturer. Yet, it is important that manufacturers and designers receive end-user feedback throughout the product development process. However, end-users often lack sufficient know-how about the technical and engineering background of the product development, and this lack of understanding can become a barrier to user-designer communication. The aim of this article is to present an alternative to traditional design approaches that is based on customized real-time multibody simulation. This simulation-based approach can be seen as a platform that has the potential to improve knowledge management systems for product development. End-user feedback to the designer is given in a systematic manner throughout the design process using a multipurpose XML-based multibody environment.

Heat Pump Dryer Design Optimization Algorithm

Drying food involves complex physical atmospheric mechanisms with non-linear relations from the air-food interactions, and those relations are strongly dependent on the moisture contents and the type of food. Such dependence makes it complex to design suitable dryers dedicated to a single drying process. To streamline the design of a novel compact food-drying machine, a heat pump dryer component design optimization algorithm was developed as a subprogram of a Computer Aided Engineering tool. The algorithm requires inputting food and air properties, the volume of the drying container, and the technical specifications of the heat pump off-the-shelf components. The heat required to dehumidify the food supplied by the heat exchange process from condenser to evaporator, and the compressor’s requirements (refrigerant mass flow rate and operating pressures) are then calculated. Compressors can then be selected based on the volume and type of food to be dried. The algorithm is shown via a flow chart to guide the user through three different stages: Changes in drying air properties, heat flow within dryer and product moisture content. Example results of how different compressors are selected for different types of produces and quantities (Agaricus blazei mushroom with three different moisture contents or fish from Thunnini tribe) conclude this article.

Automatized Monte-Carlo analysis of offshore processing of CO2-rich natural gas: Conventional versus supersonic separator routes

Offshore oil/gas production with high %CO2 and gas-to-oil ratio impose processing large volumes of CO2-rich gas. This requires first-of-a-kind designs and creates design uncertainties besides offshore operation uncertainties. Therefore, the design of offshore units under influence of stochastic factors is recommended to avoid oversized worst-case designs or underachieved specifications implying economic/environmental losses. This work presents a novel Computer-Aided Engineering tool, MCAnalysis, a VB.NET/XML interoperability framework between HYSYS and MATLAB to statistically assess design performance via Monte-Carlo analysis. Designs of offshore processing of CO2-rich gas via Conventional-Route and a novel Supersonic-Separator-Route were tested submitting stochastic populations of gas flow rate, %CO2 and gas-to-oil ratio. Supersonic-Separator-Route presented higher resilience to input overshoots and less necessity of design changes to accomplish specifications in at least 75% of sampled cases compared to Conventional-Route. Supersonic-Separator-Route also showed 15% less average power consumption and hydrocarbons dew-point adjustment with lower %CO2 in the condensate.

Numerical Investigation of the Aeroelastic Behavior of a Wind Turbine with Iced Blades

Wind turbines installed in cold-climate regions are prone to the risks of ice accumulation which affects their aeroelastic behavior. The studies carried out on this topic so far considered icing in a few sections of the blade, mostly located in the outer part of the blade, and their influence on the loads and power production of the turbine are only analyzed. The knowledge about the influence of icing in different locations of the blade and asymmetrical icing of the blades on loads, power, and vibration behavior of the turbine is still not matured. To improve this knowledge, multiple simulation cases are needed to run with different ice accumulations on the blade considering structural and aerodynamic property changes due to ice. Such simulations can be easily run by automating the ice shape creation on aerofoil sections and two-dimensional (2-D) Computational Fluid Dynamics (CFD) analysis of those sections. The current work proposes such methodology and it is illustrated on the National Renewable Energy Laboratory (NREL) 5 MW baseline wind turbine model. The influence of symmetrical icing in different locations of the blade and asymmetrical icing of the blade assembly is analyzed on the turbine’s dynamic behavior using the aeroelastic computer-aided engineering tool FAST. The outer third of the blade produces about 50% of the turbine’s total power and severe icing in this part of the blade reduces power output and aeroelastic damping of the blade’s flapwise vibration modes. The increase in blade mass due to ice reduces its natural frequencies which can be extracted from the vibration responses of the turbine operating under turbulent wind conditions. Symmetrical icing of the blades reduces loads acting on the turbine components, whereas asymmetrical icing of the blades induces loads and vibrations in the tower, hub, and nacelle assembly at a frequency synchronous to rotational speed of the turbine.

Additive Manufacturing as a Technique for <i>In Situ</i> Repair and Renovation of Marine Crankshaft Journals

This article presents the analysis and redesign of an equipment aimed at repairing in-situ the journal surface of a marine diesel engine crankshaft, based on laser cladding technology. The paper outlines the comprehensive research conducted to study the device, identify its weaknesses and establish a strategy to improve it. To address this task, we shall describe (i) a study of the working environment, (ii) performance of functional analysis using computer-aided engineering tools and finite element analysis of the current prototype, (iii) a study of the results and identification of problematic areas, (iv) proposed improvements based on the results, (v) the presentation of a 3D model with the proposed improvements.

The Use of Natural Language Processing Approach for Converting Pseudo Code to C# Code

Abstract Although current computer-aided software engineering tools support developers in composing a program, there is no doubt that more flexible supportive tools are needed to address the increases in the complexity of programs. This need can be met by automating the intellectual activities that are carried out by humans when composing a program. This paper aims to automate the composition of a programming language code from pseudocode, which is viewed here as a translation process for a natural language text, as pseudocode is a formatted text in natural English language. Based on this view, a new automatic code generator is developed that can convert pseudocode to C# programming language code. This new automatic code generator (ACG), which is called CodeComposer, uses natural language processing (NLP) techniques such as verb classification, thematic roles, and semantic role labeling (SRL) to analyze the pseudocode. The resulting analysis of linguistic information from these techniques is used by a semantic rule-based mapping machine to perform the composition process. CodeComposer can be viewed as an intelligent computer-aided software engineering (I_CASE) tool. An evaluation of the accuracy of CodeComposer using a binomial technique shows that it has a precision of 88%, a recall of 91%, and an F-measure of 89%.

The Use of Natural Language Processing Approach for Converting Pseudo Code to C# Code

Although current computer-aided software engineering tools support developers in composing a program, there is no doubt that more flexible supportive tools are needed to address the increases in the complexity of programs. This need can be met by automating the intellectual activities that are carried out by humans when composing a program. This paper aims to automate the composition of a programming language code from pseudocode, which is viewed here as a translation process for a natural language text, as pseudocode is a formatted text in natural English language. Based on this view, a new automatic code generator is developed that can convert pseudocode to C# programming language code. This new automatic code generator (ACG), which is called CodeComposer, uses natural language processing (NLP) techniques such as verb classification, thematic roles, and semantic role labeling (SRL) to analyze the pseudocode. The resulting analysis of linguistic information from these techniques is used by a semantic rule-based mapping machine to perform the composition process. CodeComposer can be viewed as an intelligent computer-aided software engineering (I_CASE) tool. An evaluation of the accuracy of CodeComposer using a binomial technique shows that it has a precision of 88%, a recall of 91%, and an F-measure of 89%.

Roof-Crush Protection Design of Automotive Bodies Using Clustering and Pattern Recognition

Computer-aided engineering (CAE) tools play an indispensable role in the vehicle development process. However, it is difficult to accurately predict the relationships and behavior of automotive bodies in vehicle crashes owing to high-order nonlinearity and numerous design variables of the automotive body structure. In this study, clustering and pattern recognition techniques were used to develop a novel optimization design of an automotive body considering roof crushing by vehicle rollover. The large-scale data were clustered to find the strong and weak clusters, and new response surface models were acquired by clustering analysis to achieve better performance than the response surface model of traditional optimization. For an efficient robust design, clusters with weak performance were excluded from the optimum solution. Finally, it was confirmed that the solutions by the proposed optimization technique were better than those obtained by the traditional optimum method based on a comparative analysis by various cluster combinations.

Data-Centric UML Profile for Wireless Sensors

Modelling WSN data behaviour is relevant since it would allow to evaluate the capacity of an application for supplying the user needs, moreover, it could enable a transparent integration with different data-centric information systems. Therefore, this article proposes a data-centric UML profile for the design of wireless sensor nodes from the user point-of-view capable of representing the gathered and delivered data of the node. This profile considers different characteristics and configurations of frequency, aggregation, persistence and quality at the level of the wireless sensor nodes. Furthermore, this article validates the UML profile through a computer-aided software engineering (CASE) tool implementation and one case study, centred on the data collected by a real WSN implementation for precision agriculture and smart farming.

Optimisation of torsional vibration system for a heavy-duty inline six-cylinder diesel engine

Torsional vibration is one of the major issues and very important calculation for the safe running of heavy-duty diesel engines, specifically crankshaft. Because of different applications of a heavy-duty diesel engine, different driven machine and different attaching systems are inevitable that affect the torsional system. The cranktrain contains the flywheel and torsional damper. The properties of these parts have significant effect on torsional vibration of the system as well as the crankshaft strength. Initial selection of these properties is usually specified based on engine designer experience and also the torsional vibration calculation of the cranktrain. In this paper, the focus is to find the optimum and reliable operating points for the elements in cranktrain using computer-aided engineering (CAE) tools. These are parameters like tuned mass inertia, flywheel inertia, damper stiffness, damper inertia, damper damping, coupling damping and coupling stiffness. The effect of these parameters on system design criteria, especially crankshaft life, was investigated. The results show high sensitivity of crankshaft safety factor to parameters like tuned mass inertia, damper damping coefficient and damper stiffness. Therefore, damper selection is the most important factor to increase the crankshaft life. The new contribution is that the parameters related to the whole cranktrain system that have the greatest effect were obtained and an optimisation was executed on these parameters to fulfil the vibration targets as well crankshaft life.

Enable Model-Based Diagnostics and Prognostics for Lithium-Ion Batteries

Physicochemical processes in lithium ion batteries occur in intricate geometries over a wide range of time and length scales. As the size of the battery increases, macroscopic design factors in combination with highly dynamic environmental conditions significantly influence the electrical, thermal, electrochemical, and mechanical responses of a battery system. Computer-aided engineering tools are helping to accelerate the design and validation of large format cells and battery pack systems, which heavily replies on costly and time-consuming experimental tests previously. Validated physics-based models are effective in predicting electrochemical performance, thermal and mechanical response of cells and packs under normal and abuse scenarios and provide valuable insights not possible through experimental testing alone for diagnostics and prognostic purpose. NREL pioneered the Multi-Scale Multi-Domain (MSMD) battery model, overcoming challenges in modeling the highly nonlinear multi-scale response of battery systems. The MSMD model provides flexibility and multi-physics expandability through its modularized architecture. The presentation describes present efforts to develop approaches to make the models better suited for engineering diagnostics and prognostic for large lithium-ion battery units by Enhancing computation speed and stability of the pack-level multi-scale model while still resolving nonlinearities of dynamic battery response across scales from particles to packsBlending field simulation with system simulation in a selective fashion to balance speed and accuracy. Applicable techniques include domain decomposition, physics segregation and reduced-order models (ROM) that can integrate into the system modelDeveloping interactive system interface for enhancement of multi-physics integrityIncorporating spatially distributed model to address 3D non-uniform usage and stress factors.

CAD/CAE of Jaipur foot for standardized and contemporary manufacturing

Objective: Despite immense popularity of Jaipur foot as low cost prosthetic, not much work has been reported on its design for manufacturing standardization. Without manufacturing standardization, it cannot be mass produced using contemporary manufacturing technologies. The objective of this work is to carry out its computer aided design (CAD) followed by computer aided engineering (CAE) based on the material properties obtained from the previous work [1] of the authors. This may lead to the possible use of modern manufacturing processes for the Jaipur foot design.Design: After modelling using CAD tool including its organic surfaces, the designed foot was analysed using a CAE tool for balanced standing load conditions to determine maximum stresses and deformation in its various parts. The bending analysis was done to check the dorsiflexion movement so that the strained sections could be identified for more reliable and durable prosthetic foot. For the static load analysis, base of the foot was constrained and 300–500 N load was applied through the bolt whereas for bending, the part near the bolt was fixed and pressure was applied at junction of front foot and toes.Results: The results show that the maximum stress and deformation occur at the bolt, while the skin undergoes maximum strain. CAE analysis also proves the robustness of the Jaipur foot design and a well manufactured Jaipur foot as per standardized design should be able to withstand the real life conditions without failure. The CAD model is also used for FDM based printing for a nonfunctional prototype of Jaipur foot.Implications for rehabilitationThe results of this study will serve as an important guideline for further research regarding equivalent material replacement, material optimization and obtaining an optimized design after studying the foot for dynamic analysis.

Integrating modern virtual engineering tools in footwear design and development

Footwear prototyping is constrained by significant volume of “sampling”, time to market pressures, cost implications and the failure of the industry to attract and develop high quality professionals mastering modern computer-aided product development. Computer-Aided Engineering (CAE) and material selection are becoming increasingly important transforming factors of this process raising the question of how to best integrate them into the design function considering not only infrastructure issues but also human resources and financing. Their role in footwear development is presented in this paper, based on the view of design as a multistage process subject to Concurrent Engineering. Proposed interventions to the design process for exploiting modern CAE and material selection tools are discussed, taking into account the business Value Chain Model and modern Cloud Service approaches. Innovative approaches to harness the processing power of modern CAE tools are identified and related to business practices, considering, also, the role of product development professionals and financing constraints. In particular, the application of the cloud service model of managing Software as a Service is discussed along with relevant opportunities and limitations. The paper concludes with an overall assessment of the impact that this model may have on the footwear industry.

Modeling and validation of the effects of processing parameters on the dimensional stability of an injection-molded polypropylene plate

There has recently been a growing amount of interest in developing process control methods to maintain consistent part quality during injection molding. Some commercially available control methods are believed to offer improved machine and process capability in order to achieve this goal. Regardless of these advantages, however, these methods typically require considerable experimentation before an optimal process setting can be obtained for a particular case. Therefore, a more systematic scheme that does not require extensive experimentation, which in turn costs time and money, is needed. Computer-aided engineering (CAE) is considered to be a good tool for predicting the flow behavior in the cavity during the filling and post-filling stages. If CAE software can accurately predict a part quality indicator, such as one concerned with the dimensional stability, under a given process condition, time-consuming experimentation would no longer be necessary to determine the relationship between the process conditions and part quality. However, the relationship between the process conditions and part quality indicators, such as the dimensional stability, is highly nonlinear and takes no explicit form. The goal of this study is to use CAE tools to establish such a relationship and generate part quality data based on predictions. A second-order regression model is established in order to correlate the part quality with four key process variables using an optimization technique. Finally, we obtain the reference values under these process conditions. A case study was conducted using both a simulation and experimentation for a plaque-shaped piece of polypropylene. The results indicate reasonable agreement between the simulation and experimentation.

Current state and trajectory of design engineering in Kenya

In the last few decades, the methods and models of engineering design practices have changed drastically due to the introduction of better technology and sophisticated design tools. Engineers are now moving away from manual design and drafting using A4 paper sheets, rulers and tri-squares to the use of computer-aided engineering tools in designing and manufacturing. These new advances in engineering design practices have led to huge increases in efficiency gains in engineering practices that, in turn, result in better infrastructure and, ultimately, economic growth and social development. Kenya needs to pay more attention to the changes in technology and expertise in the field of engineering to improve the nation’s economy. Even though Kenya, and Africa at large, are growing rapidly in technology and in the field of engineering design, there is still a big chasm between the continent and the developed countries in the practice and education of engineering design. This paper argues that more should be done in accelerating the uptake of engineering design technologies in Kenya and by the same token in the wider Africa.

Optimized power management based on adaptive-PMP algorithm for a stationary PEM fuel cell/battery hybrid system

This research develops an efficient and robust polymer electrolyte membrane (PEM) fuel cell/battery hybrid operating system. The entire system possesses its own rapid dynamic response benefited from hybrid connection and power split characteristics due to DC/DC buck-boost converter. An indispensable energy management system (EMS) plays a significant role in achieving optimal fuel economy and in a promising running stability. EMS as an indispensable part plays a significant role in achieving optimal fuel economy and promising operation stability. This study aims to develop an adaptive supervisory EMS that comprises computer-aided engineering tools to monitor, control, and optimize the performance of the hybrid power system. A stationary fuel cell/battery hybrid operating system is optimized using adaptive-Pontryagin's minimum principle (A-PMP). The proposed algorithm depends on the adaptation of the control parameter (i.e., fuel cell output power) from the state of charge (SOC) and load power feedback. The integrated model simulated in a Matlab/Simulink environment includes the fuel cell, battery, DC/DC converter, and power requirements models by analyzing the three different load profiles. Real-time experiments are performed to verify the effectiveness of EMS after analyzing the simulated operating principle and control scheme.

CAD TOOLS AND FILE FORMAT PERFORMANCE EVALUATION IN DESIGNING LATTICE STRUCTURES FOR ADDITIVE MANUFACTURING

Additive manufacturing has opened the door to the creation of lightweight lattice structures. However, present Computer-Aided Design (CAD) and Computer-Aided Engineering (CAE) software are unsuitable for these types of structures. The objective of this research is to examine the performances of current CAD and CAE software to design lattice structures and to demonstrate their limitations and propose requirements for future developments. A performance evaluation of a case study for lattice structure designs was conducted. The criteria used for the evaluation were CAD human-machine-interface, RAM consumption, data exchange between CAD, CAE and CAM tools and finite element analysis (FEA) duration and file sizes. The CAD tool was incapable of executing a repetition function for octet-truss lattice structures of 150 x 150 x 150 mm dimensions or larger and the software stopped working. For 70 × 70 × 70 mm octet-truss lattice structure, the FEA computation file size reached 36.6 GB. The CAD file size of a 200 x 200 x 200 mm octet-truss lattice structure reached nearly 290 MB. In conclusion, this study exposes the performance inadequacy of current CAD and CAE tools and CAD file formats to design lattice structures for additive manufacturing parts.